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#1
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Redesign of Carver's D-500 Amplifier under Phase Linear Corp
I have owned my venerable Phase Linear D-500 amplifier since 1978. It was
the last amplifier that Bob Carver designed before he left the Phase Linear Corporation to start his new business. Over the years, I have done several maintenance items on this amplifier, mostly related to re-capping. The majority of problems were due to capacitors drying out on the board that controls the amplifier's functions. I've replaced these over the years. Just recently, the transistor that controls the latch circuit which powers the main relay for switchings mains power to the large power transformer had developed an intermittent breakdown where the amp would occasionally turn itself on with no one pressing the front panel button. Since I didn't have an MPSA42 on hand, I replaced with a 2N3440, with just as good as new results. Integrating this amp into my racks a number of years ago brought about a problem: hum. The amp threw a lot of magnetic energy into everything made of metal that was nearby. Especially with direct condution from the D-500 chassis to the rails of the rack. I decided to redo my rack configuration this month in an attempt to fix the problem by isolating low level systems from power systems. While I was at it, I did a little bit of needed maintenance on several pieces of gear. While inside the D-500, it occured to me what an awful job of engineering went on as far as wiring and grounding topology was concerned. These guys wired the amp in the most wasteful, noise-attracting way possible! I found several wiring no-nos and gradually worked on fixing them. Before I get to details, I should point out that this amp always showed a bit of instability in the form of ultrasonic oscillation, when driven to clipping, since it was bought new. (I love to put all my amps into dummy loads and put a scope and signal generator on them to measure the real power output.) Getting back to details now, I ended up cutting out about 60% of the wiring lengths where B+/- voltages were running around the chassis. They had the DC, AC and low level audio wiring bundled together. No wonder I would hear a buzz when a light dimmer was turned part way on in the house. Every wire went into one harness. Even more unbelievable was the fact that the ground for the driver board and audio inputs was taken off the negative terminal of the left and right speaker outputs! No wonder I was measuring crosstalk garbage in the undriven channel when the driven (other) channel was driven to clipping. I proceeded to correct these deficiencies, observing the "star topology" of grounding methods. I moved the driver board ground to the power supply ground, at the junction of the two big capacitors. I unbundled all the leads carrying AC, DC and audio and shortened the DC power leads by directly routing them to the capacitors from the output stage. I shortened the ground leads in the same manner. The next thing I did was add a second 25 amp bridge rectifier to the power supply. I ran separate parallel wiring from that to the Low/Hi Z relay and parallel wiring to the +/- capacitor terminals. At an earlier time, I had replaced the original electrolytic capacitors with much larger 45,000uF capacitors. Recent research made me aware that the ESR of electrolytics is not so good above 1000hz, so I added 4.4uf of poly capacitors across each power supply rail, to improve the ESR at higher frequencies. I shortened the audio wiring from the rear apron, routing it directly to the front panel, instead of letting it run parallel to 110 vac wiring in a bundle. To cure a slight left channel hum, I ended up placing/gluing a strip of copper clad PCB on the left edge of the driver PCB, right over the 5" trace of unshielded audio input, grounding that strip to audio ground. That quieted the left channel hum. Over the course of these modifications, wiring was shortened, leads carrying diverse signal types were segregated, and grounding was corrected so that all systems share a star topology. The result? The crosstalk between left and right channels is gone. The amp doesn't oscillate when driven to clipping anymore. The power supply is stiffer and doesn't sag under load. Subjective impression? The noise is gone. Music emerges from a blanket of silence. There seems to be a greater clarity and detail and the soundstage is wide and deep. Transient response is crisp. The amp sounds better today than it did when it was new. In fact, now that I isolated the amp from the rest of the equipment by insulating it from the rack rails electrically, the pervasive hum that plagued me is gone to inaudible on my ultra-efficient speakers. I'm sure there are other things I could further do to make subtle measureable improvements, but the changes made so far have resulted in pretty radical improvements. I'm quite surprised that Phase Linear would design such marvelous circuit topology, but completely screw up the wiring topology. But having corrected that, the true sheen of this amplifier is realized. -- Take care, Mark & Mary Ann Weiss VIDEO PRODUCTION . FILM SCANNING . DVD MASTERING . AUDIO RESTORATION Business sites at: www.dv-clips.com www.mwcomms.com www.adventuresinanimemusic.com - |
#2
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I'm sure there are other things I could further do to make subtle measureable improvements, but the changes made so far have resulted in pretty radical improvements. I'm quite surprised that Phase Linear would design such marvelous circuit topology, but completely screw up the wiring topology. But having corrected that, the true sheen of this amplifier is realized. The three most important factors affecting audio quality in electronics are layout, layout and layout. The best topology, choice of transistors, ICs or tubes don't matter if the layout stinks. |
#3
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On Sat, 25 Dec 2004 07:59:51 GMT, "Karl Uppiano"
wrote: I'm sure there are other things I could further do to make subtle measureable improvements, but the changes made so far have resulted in pretty radical improvements. I'm quite surprised that Phase Linear would design such marvelous circuit topology, but completely screw up the wiring topology. But having corrected that, the true sheen of this amplifier is realized. The three most important factors affecting audio quality in electronics are layout, layout and layout. The best topology, choice of transistors, ICs or tubes don't matter if the layout stinks. Well that's a bit one-eyed. Layout is certainly important to a GOOD design, and you certainly got that point across, but it's ALL got to be good to get a good result, including topology, devices, and ... let me see .. oh yes ... the design! Tony (remove the "_" to reply by email) |
#4
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"Mark & Mary Ann Weiss" wrote in
k.net: I have owned my venerable Phase Linear D-500 amplifier since 1978. It was the last amplifier that Bob Carver designed before he left the Phase Linear Corporation to start his new business. Over the years, I have done several maintenance items on this amplifier, mostly related to re-capping. The majority of problems were due to capacitors drying out on the board that controls the amplifier's functions. I've replaced these over the years. Just recently, the transistor that controls the latch circuit which powers the main relay for switchings mains power to the large power transformer had developed an intermittent breakdown where the amp would occasionally turn itself on with no one pressing the front panel button. Since I didn't have an MPSA42 on hand, I replaced with a 2N3440, with just as good as new results. Integrating this amp into my racks a number of years ago brought about a problem: hum. The amp threw a lot of magnetic energy into everything made of metal that was nearby. Especially with direct condution from the D-500 chassis to the rails of the rack. I decided to redo my rack configuration this month in an attempt to fix the problem by isolating low level systems from power systems. While I was at it, I did a little bit of needed maintenance on several pieces of gear. While inside the D-500, it occured to me what an awful job of engineering went on as far as wiring and grounding topology was concerned. These guys wired the amp in the most wasteful, noise-attracting way possible! I found several wiring no-nos and gradually worked on fixing them. Before I get to details, I should point out that this amp always showed a bit of instability in the form of ultrasonic oscillation, when driven to clipping, since it was bought new. (I love to put all my amps into dummy loads and put a scope and signal generator on them to measure the real power output.) Getting back to details now, I ended up cutting out about 60% of the wiring lengths where B+/- voltages were running around the chassis. They had the DC, AC and low level audio wiring bundled together. No wonder I would hear a buzz when a light dimmer was turned part way on in the house. Every wire went into one harness. Even more unbelievable was the fact that the ground for the driver board and audio inputs was taken off the negative terminal of the left and right speaker outputs! No wonder I was measuring crosstalk garbage in the undriven channel when the driven (other) channel was driven to clipping. I proceeded to correct these deficiencies, observing the "star topology" of grounding methods. I moved the driver board ground to the power supply ground, at the junction of the two big capacitors. I unbundled all the leads carrying AC, DC and audio and shortened the DC power leads by directly routing them to the capacitors from the output stage. I shortened the ground leads in the same manner. The next thing I did was add a second 25 amp bridge rectifier to the power supply. I ran separate parallel wiring from that to the Low/Hi Z relay and parallel wiring to the +/- capacitor terminals. At an earlier time, I had replaced the original electrolytic capacitors with much larger 45,000uF capacitors. Recent research made me aware that the ESR of electrolytics is not so good above 1000hz, so I added 4.4uf of poly capacitors across each power supply rail, to improve the ESR at higher frequencies. I shortened the audio wiring from the rear apron, routing it directly to the front panel, instead of letting it run parallel to 110 vac wiring in a bundle. To cure a slight left channel hum, I ended up placing/gluing a strip of copper clad PCB on the left edge of the driver PCB, right over the 5" trace of unshielded audio input, grounding that strip to audio ground. That quieted the left channel hum. Over the course of these modifications, wiring was shortened, leads carrying diverse signal types were segregated, and grounding was corrected so that all systems share a star topology. The result? The crosstalk between left and right channels is gone. The amp doesn't oscillate when driven to clipping anymore. The power supply is stiffer and doesn't sag under load. Subjective impression? The noise is gone. Music emerges from a blanket of silence. There seems to be a greater clarity and detail and the soundstage is wide and deep. Transient response is crisp. The amp sounds better today than it did when it was new. In fact, now that I isolated the amp from the rest of the equipment by insulating it from the rack rails electrically, the pervasive hum that plagued me is gone to inaudible on my ultra-efficient speakers. I'm sure there are other things I could further do to make subtle measureable improvements, but the changes made so far have resulted in pretty radical improvements. I'm quite surprised that Phase Linear would design such marvelous circuit topology, but completely screw up the wiring topology. But having corrected that, the true sheen of this amplifier is realized. -- Take care, Mark & Mary Ann Weiss Good job on the amp! I recently re-worked the 2 MC2500 amps that I have. There was one "mistake" they made with those amps and that was to run the 120VAC line for the fans too close to the inputs. Re-dressing the leads lowered the hum/buzz to inaudible. Noise floor is now a respectable 100db down or more. I could have worked at lowering it more, but there is no point. Inaudible is inaudible after all. r -- Nothing beats the bandwidth of a station wagon filled with DLT tapes. |
#5
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"Tony" wrote in message ... On Sat, 25 Dec 2004 07:59:51 GMT, "Karl Uppiano" wrote: I'm sure there are other things I could further do to make subtle measureable improvements, but the changes made so far have resulted in pretty radical improvements. I'm quite surprised that Phase Linear would design such marvelous circuit topology, but completely screw up the wiring topology. But having corrected that, the true sheen of this amplifier is realized. The three most important factors affecting audio quality in electronics are layout, layout and layout. The best topology, choice of transistors, ICs or tubes don't matter if the layout stinks. Well that's a bit one-eyed. Layout is certainly important to a GOOD design, and you certainly got that point across, but it's ALL got to be good to get a good result, including topology, devices, and ... let me see .. oh yes ... the design! You'll get no argument from me. It was hyperbolic. But layout gets short shrift all to often from vendors that should know better. My post was a parody of the real-estate "location, location, location" mantra. Obviously, a tar paper lean-to won't be a good investment, regardless of the location. |
#6
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fresh from the hospital, nursery, or morgue;
you can at least get rid of all the leftovers in your refrigerator. 1 - 2 lbs. cubed meat (human flesh, chicken, turkey, beef...) 1 -2 lbs. coarsely chopped vegetables (carrots, potatoes, turnips, cauliflower, cabbage...) Bell pepper onions garlic ginger salt pepper, etc. Olive oil butter Brown the meat and some chopped onions, peppers, and garilic in olive oil, place in baking dish, layer with vegetables seasoning and butter. Bake at 325° for 30 - 45 minutes. Serve with hot dinner rolls, fruit salad and sparkling water. Bébé Buffet 1 Show off with whole roasted children replete with apples in mouths - and babies? heads stuffed with wild rice. Or keep it simple with a hearty main course such as stew, lasagna, or meat loaf. Some suggestions Pre-mie pot pies, beef stew, leg of lamb, stuffed chicken, roast pork spiral ham, Cranberry pineapple salad, sweet potatoes in butter, vegetable platter, tossed salad with tomato and avocado, parsley new potatoes, spinich cucumber salad, fruit salad Bran muffins, dinner rolls, soft breadsticks, rice pilaf, croiss |
#7
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on the skewers.
Don?t be afraid to use a variety of meats. Grill to medium rare, serve with garlic cous-cous and sautéed asparagus. Coffee and sherbet for desert then walnuts, cheese, and port. Cigars for the gentlemen (and ladies if they so desire)! Crock-Pot Crack Baby When the quivering, hopelessly addicted crack baby succumbs to death, get him immediately butchered and into the crock-pot, so that any remaining toxins will not be fatal. But don?t cook it too long, because like Blowfish, there is a perfect medium between the poisonous and the stimulating. Though it may not have the same effect on your guests, a whole chicken cooked in this fashion is also mighty tasty. 1 newborn - cocaine addicted, freshly expired, cleaned and butchered Carrots onions leeks celery bell pepper potatoes Salt pepper garlic, etc 4 cups water Cut the meat into natural pieces and brown very well in olive oil, remove, then brown half of the onions, the bell pepper, and celery. When brown, mix everything into the crock-pot, and in 6 to 8 hours you have turned a hopeless tragedy into a heartwarming meal! George?s Bloody Mary Don?t shy away from this one, it is simply a cocktail variation of good old Blood Stew. When a pi |
#8
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On Sat, 25 Dec 2004 09:36:53 GMT, "Karl Uppiano"
wrote: "Tony" wrote in message .. . On Sat, 25 Dec 2004 07:59:51 GMT, "Karl Uppiano" wrote: I'm sure there are other things I could further do to make subtle measureable improvements, but the changes made so far have resulted in pretty radical improvements. I'm quite surprised that Phase Linear would design such marvelous circuit topology, but completely screw up the wiring topology. But having corrected that, the true sheen of this amplifier is realized. The three most important factors affecting audio quality in electronics are layout, layout and layout. The best topology, choice of transistors, ICs or tubes don't matter if the layout stinks. Well that's a bit one-eyed. Layout is certainly important to a GOOD design, and you certainly got that point across, but it's ALL got to be good to get a good result, including topology, devices, and ... let me see .. oh yes ... the design! You'll get no argument from me. It was hyperbolic. But layout gets short shrift all to often from vendors that should know better. My post was a parody of the real-estate "location, location, location" mantra. Obviously, a tar paper lean-to won't be a good investment, regardless of the location. Sorry - I was a bit slow on the uptake there. But a tar paper lean-to? that's another matter, probably a great investment, and won't cost much to knock down. Tony (remove the "_" to reply by email) |
#9
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Sherry
chicken broth oil for deep frying (1 gallon) Salt pepper soy & teriyaki minced ginger, etc. 1 tablespoon cornstarch dissolved in a little cold water 1 egg beaten Make the stuffing: Marinate the flesh in a mixture of soy and teriyaki sauces then stir fry in hot oil for till brown - about 1 minute, remove. Stir-fry the vegetables. Put the meat back into the wok and adjust the seasoning. De-glaze with sherry, cooking off the alcohol. Add broth (optional) cook a few more minutes. Add the cornstarch, cook a few minutes till thick, then place the stuffing into a colander and cool; 2 hours Wrap the rolls: Place 3 tablespoons of stuffing in the wrap, roll tightly - corner nearest you first, fold 2 side corners in, wrap till remaining corner is left. Brush with egg, seal, and allow to sit on the seal for a few minutes. Fry the rolls: 325° if using egg roll wraps, 350° for spring roll wraps. Deep fry in peanut oil till crispy golden brown, drain on paper towels. Lemon Neonate Turkey serves just as well, and in fact even looks a bit like a well-dressed baby. By the time you turn the child?s breast into |
#10
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green beans work especially well. Meat is not necessary every day, don?t
be afraid to alter any dish to vegetarian tastes. 1 premature baby, born dead Large bunch of mustard greens 2 white onions, 1 cup chopped celery Vegetable oil (or hog fat) Salt, pepper, garlic, etc. Lightly brown onions, celery, garlic and meat in large heavy pot. Add a little water and the greens (which should be thoroughly cleaned and washed). Smother slowly for at least 2 hours, adding small amounts of water when it starts to stick. Stir frequently. When ready - serve with rice, grilled smoked sausage, green salad, and iced tea. Coffee and apple pie then brandy. Maternity Ward Pot Luck Dinner If you can?t get anything fresh from the hospital, nursery, or morgue; you can at least get rid of all the leftovers in your refrigerator. 1 - 2 lbs. cubed meat (human flesh, chicken, turkey, beef...) 1 -2 lbs. coarsely chopped vegetables (carrots, potatoes, turnips, cauliflower, cabbage...) Bell pepper onions garlic ginger salt pepper, etc. Olive oil butter Brown the meat and some chopped onions, peppers, and garilic in olive oil, place in baking dish, layer with vegetables seasoning and butter. Bake at 325° for 30 - 45 minutes. Serve with hot dinner rolls, fruit salad and sparkling water. Bébé Buffet 1 Show off with whole roasted children replete with apples in mouths - and babies? heads stuffed with wild rice. Or keep it simple with a hearty main course such as stew, lasagna, or meat loaf. Some suggestions Pre-mie pot pies, beef stew, leg of lamb, stuffed chicken, roast pork spiral ham, Cranberry pineapple salad, sweet potatoes in butter, vegetable platter, tossed salad with tomato |
#11
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Karl Uppiano wrote: I'm sure there are other things I could further do to make subtle measureable improvements, but the changes made so far have resulted in pretty radical improvements. I'm quite surprised that Phase Linear would design such marvelous circuit topology, but completely screw up the wiring topology. As a rule, it costs little or nothing to do the wiring layout *right*. The three most important factors affecting audio quality in electronics are layout, layout and layout. OK, hyperbole. The best topology, choice of transistors, ICs or tubes don't matter if the layout stinks. Conversely, the layout doesn't matter if there's something significantly wrong with the other choices. |
#12
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shall eat.
Leviticus 26:29 Roast Child with Cornbread Stuffing Turkey may be substituted for this classic holiday feast. Although time consuming, this dish seems to take longer than it actually does; as the entire house is filled with such a heavenly aroma, the waiting becomes almost unbearable. 1 whole child, cleaned and de-headed 1 batch cornbread stuffing (see index) ½ cup melted butter Remove the giblets from the infant and set aside. Stuff the cavity where the child?s genitals and anus were located using ½ cup per pound of meat. Tie the arms flat to the body, then pull the skin flaps up to close the cavity. Now tie the thighs up tight to hold it all together. Place breast side up in a large metal roasting pan. Bake in 325° oven covered for 2 hours. Remove cover, stick a cooking thermometer deep into one of the baby?s buttocks and cook uncovered till thermometer reads 190°, about another hour. Pro-Choice Po-Boy Soft-shelled crabs serve just as well in this classic southern delicacy. The sand |
#13
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Onion, garlic
Salt pepper garlic powder cayenne pepper hot sauce, etc. Oil for frying Mix milk, eggs, hot sauce in a bowl, add chopped onion and garlic. Season the meat liberally, and marinate for several hours. Place seasoned flour in a paper or plastic shopping bag, drop pieces in a few a time, shake to coat thoroughly, then deep fry in hot oil (350°) for about 15 minutes. Drain and place on paper towels. Miscarriage with Mustard Greens Why waste it? Otherwise, and in general, use ham or salt pork to season greens. The technique of smothering greens can be used with many vegetables; green beans work especially well. Meat is not necessary every day, don?t be afraid to alter any dish to vegetarian tastes. 1 premature baby, born dead Large bunch of mustard greens 2 white onions, 1 cup chopped celery Vegetable oil (or hog fat) Salt, pepper, garlic, etc. Lightly brown onions, celery, garlic and meat in large heavy pot. Add a little water and the greens (which should be thoroughly cleaned and washed). Smother slowly for at least 2 hours, adding small amounts of water when it starts to stick. |
#14
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shoots
Sherry chicken broth oil for deep frying (1 gallon) Salt pepper soy & teriyaki minced ginger, etc. 1 tablespoon cornstarch dissolved in a little cold water 1 egg beaten Make the stuffing: Marinate the flesh in a mixture of soy and teriyaki sauces then stir fry in hot oil for till brown - about 1 minute, remove. Stir-fry the vegetables. Put the meat back into the wok and adjust the seasoning. De-glaze with sherry, cooking off the alcohol. Add broth (optional) cook a few more minutes. Add the cornstarch, cook a few minutes till thick, then place the stuffing into a colander and cool; 2 hours Wrap the rolls: Place 3 tablespoons of stuffing in the wrap, roll tightly - corner nearest you first, fold 2 side corners in, wrap till remaining corner is left. Brush with egg, seal, and allow to sit on the seal for a few minutes. Fry the rolls: 325° if using egg roll wraps, 350° for spring roll wraps. Deep fry in peanut oil till crispy golden brown, drain on paper towels. Lemon Neonate Turkey serves just as well, and in fact even looks a bit like a well-dressed baby. By the time you turn the child?s breast into cutlets, it will be indistinguishable. The taste of young human, although similar to turkey (and chicken) often can be wildly different depending upon what he or she has consumed during its 10 to 14 months of life... 4 well chosen cutlets (from the breasts of 2 healthy neonates) 2 large lemons (fresh lemons always, if possible) Olive oil Green onions Salt pepper corn |
#15
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On Sat, 25 Dec 2004 06:56:15 GMT, "Mark & Mary Ann Weiss"
wrote: I have owned my venerable Phase Linear D-500 amplifier since 1978 snip And nothing's burned up?? Amazing! the last amplifier that Bob Carver designed before he left the Phase Linear Corporation to start his new business. snip You mean "fired." Over the years, I have done several maintenance items on this amplifier, mostly related to re-capping. The majority of problems were due to capacitors drying out on the board that controls the amplifier's functions. I've replaced these over the years. snip "Flames In-Yer-Ear" amps were famous for Carver's idiotic unmatched outputs. The 700B was known for torching many clubs and other venues by having the overheated outputs go to Vcc and set the woofer of whatever it was driving on fire, and so was the D-500. Boat anchors to which Bob the Slob should have been tied to long ago before being dumped in the bay. dB |
#16
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Good job on the amp!
I recently re-worked the 2 MC2500 amps that I have. There was one "mistake" they made with those amps and that was to run the 120VAC line for the fans too close to the inputs. Re-dressing the leads lowered the hum/buzz to inaudible. Noise floor is now a respectable 100db down or more. I could have worked at lowering it more, but there is no point. Inaudible is inaudible after all. r I was on a mission to eliminate hum, being the speaker systems in use have a 105dB @1W sensitivity rating. Even the smallest hum becomes room-filling on these speakers. As I got into the D-500, I discovered a lot of things the just irritated me and that I could not leave be. So I ended up spending two nights rewiring it. The problem with this amplifier is the power transformer--it's humungous and radiates 60 cycle magnetic fields that a dynamic microphone can pick up from 5' away. Isolating it from the rack was the final solution. I modified the rack handle mounting, changing from the 1/4 20 pan head screws to flat head recessed screws, after using a countersinking bit to create the recess in the back of the flange and part of the 1/8" thick front panel. Then I applied a 1/16" rubber adhesive strip to the back side and used insulated washers on the 10-32 screws that secure it to the rails. For twenty years (1984 was the year I expanded my studio and moved the equipment to racks) I endured that hum and now to be finally free of it is a wonderful thing. Hum and hiss are down around 10dBa now, about 30dB down from where they were. While I was in the mood, I also reworked the passive network filters that cross from midrange drivers to tweeters. I replaced the 1st-order network with a 2nd-order network, providing a much steeper rolloff below 4kc. The goal here was to protect the tweeters from excessive excursions down around 1kc, since the D-500 can push significant power levels into the speakers in the circuit with drive levels of many hundreds of watts possible at the tweeters. I'm very pleased with the results, and starting to find that my direct to disc vinyl recordings sound more spacious and have better imaging that the CD versions of the same performances that I possess. I can't wait to hear my first 24/96 digital recording of a local symphony orchestra. I expect that such resolution should provide the spaciousness and imaging that my 16-bit CDs seem to lack. -- Take care, Mark & Mary Ann Weiss VIDEO PRODUCTION • FILM SCANNING • DVD MASTERING • AUDIO RESTORATION Business sites at: www.dv-clips.com www.mwcomms.com www.adventuresinanimemusic.com - |
#17
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I have owned my venerable Phase Linear D-500 amplifier since 1978 snip And nothing's burned up?? Amazing! I look inside that amp, and it scares me, every time. And that is coming from a guy who regularly pokes his head inside 50kW FM broadcast transmitters as part of my day job! I keep hoping that nothing ever goes wrong in there, as the consequences could be very unpleasant. the last amplifier that Bob Carver designed before he left the Phase Linear Corporation to start his new business. snip You mean "fired." I hadn't heard that. If that be the case, it had to be a personality clash, not a performance issue. Bob is a very intelligent and creative engineer. His products are nothing short of stunning, albeit he shortcuts on the quality of components, such as switches. Over the years, I have done several maintenance items on this amplifier, mostly related to re-capping. The majority of problems were due to capacitors drying out on the board that controls the amplifier's functions. I've replaced these over the years. snip "Flames In-Yer-Ear" amps were famous for Carver's idiotic unmatched outputs. The 700B was known for torching many clubs and other venues by having the overheated outputs go to Vcc and set the woofer of whatever it was driving on fire, and so was the D-500. I've had woofers catch on fire, but not from amp failure--but from overdriving them. I remember a repair ticket for a non-warranty repair that Electro-Voice did on an 18B low frequency driver saying, "voice coil burnt BLACK". :-) In practice, the D-500 has run cool and the worst that has happened was the LOW Z setting would be tripped. The protection circuitry is far too sensitive. Boat anchors to which Bob the Slob should have been tied to long ago before being dumped in the bay. dB I think that's a bit harsh. He may not be such a great businessman, and perhaps you've had a bad experience with one of his amps, but overall, I think the man's a genius. -- Take care, Mark & Mary Ann Weiss VIDEO PRODUCTION . FILM SCANNING . DVD MASTERING . AUDIO RESTORATION Business sites at: www.dv-clips.com www.mwcomms.com www.adventuresinanimemusic.com - |
#18
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"Mark & Mary Ann Weiss" wrote in
ink.net: I was on a mission to eliminate hum, being the speaker systems in use have a 105dB @1W sensitivity rating. Even the smallest hum becomes room-filling on these speakers. As I got into the D-500, I discovered a lot of things the just irritated me and that I could not leave be. So I ended up spending two nights rewiring it. Mark & Mary Ann Weiss 500 watts into a a speaker with 105 db @1watt sensitivity? That is a bit much even for me! (:) Doesn't that comes to about 132db at 512 watts? You are fortunate that the transformer mechanical hum issue was able to be addressed with mounting changes. Many times the transformer itself hums and there is no recourse but to replace the transformer or the amp. r -- Nothing beats the bandwidth of a station wagon filled with DLT tapes. |
#19
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DeserTBoB wrote:
"Flames In-Yer-Ear" amps were famous for Carver's idiotic unmatched outputs. The 700B was known for torching many clubs and other venues by having the overheated outputs go to Vcc and set the woofer of whatever it was driving on fire, and so was the D-500. Boat anchors to which Bob the Slob should have been tied to long ago before being dumped in the bay. It sounds to me like these clubs of legend were driving an amp hard without properly ventilating them, so any fires or problems resulting from failure due to overheating would seem to be more the fault of the club rather than the amplifier or its designer. The owner's manual does have a mention of 'adequate ventilation.' I speak from experience. I worked for a touring sound company that used Phase Linear 200's, 400's and 700's exclusively into the 90's. Yes, we had amps fail but rarely in the manner of the 'Flame Linear' legend, more due to thin sheet metal chassis coming apart because they weren't designed for touring use or stagehands pushing transistor covers onto transistors between the fins of heat sinks and causing shorts or bad power blowing fuses. With about 35 Phase Linear amps we'd have maybe four channel failures a year due to causes not related to operator error, and we worked 'em hard. We had many more problems related to band engineers who associated distortion with loudness and stagehands who think they're airline baggage handlers. Amps these days are loaded with protection circuits the PL's didn't have and designers have much better simulation tools available, Carver did an excellent job given the era he did it in. We'd modified them to some extent, putting in B+/B- fuses on the front panel for each channel, unbolting the transformer from the chassis and bolting it to the rack, installing a support for the supply filter caps, adding 1/4" connectors in place of the RCA's, putting fans and vents in the racks. They were reliable workhorses that gave us few problems. Considering their peers (other big amps available in the late 70's) if you were smarter than the amp (a lot to ask, I know) they were great. |
#20
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I was on a mission to eliminate hum, being the speaker systems in use have a 105dB @1W sensitivity rating. Even the smallest hum becomes room-filling on these speakers. As I got into the D-500, I discovered a lot of things the just irritated me and that I could not leave be. So I ended up spending two nights rewiring it. Mark & Mary Ann Weiss 500 watts into a a speaker with 105 db @1watt sensitivity? That is a bit much even for me! (:) Doesn't that comes to about 132db at 512 watts? There is a modification to the protection limiter circuit which, in stock D-500s, limits the swing of the output transistors to a little over 180v p-p, but can be delayed or disabled to allow the output to swing within 10 volts of Vcc (250v p-p), raising the power output into 8 ohms from 505 watts to a little over 976 watts. The power supply provides +/- 125VDC, so it would be a shame not to be able to use it. The rough & dirty approach is to clip out D102 and D111. Voila, instant power upgrade for 8-ohm users. The more elegant approach is to delay the response of the clipper circuit for 10mS, long enough to convey transients, but to safely limit long-term abuse, adding 3dB of dynamic headroom. And why not? The output stage is rated for 8,000 watts. And yes, I wanted unclipped reproduction at levels exceeding 130dB. The sensitivity of the woofer array is considerably higher, and it is complex to calculate it, because of the array of amplifiers driving them. I've got the Hafler 500s each bridged for mono and modified with beefed up power supply capacitors (special order from Phillips, manufactured to my spec), swinging 320 volts p-p into the 4-ohm load of the subwoofers on the ends of the system, providing an time-limited un-clipped power output of 2060 watts per dual woofer array. I once did a pink noise test with 2 v RMS reading at the speaker connection terminals using an HP 400E RMS voltmeter and took SPL readings of 112dB at 4'. On another occasion, I took an SPL reading from 32' away, at the back end of the studio, during the opening 16hz organ pedal heard in Telarc's 'Also Sprach Zarathustra', and noted a steady reading of 122dB (although I could barely hear it, the whole building was quivering and the experience was borderline nauseating) and the system was barely above idling power. Needless to say, the hum problems were an extraordinary challenge to rid from this system. You are fortunate that the transformer mechanical hum issue was able to be addressed with mounting changes. Many times the transformer itself hums and there is no recourse but to replace the transformer or the amp. r There is some mechanical hum from the amplifier chassis itself, but worse is the noise of the cooling fans in the Haflers and the big blower on the bottom of the rack, which, despite being operated on a variac at 60 vac, still provides enough noise to ruin a soft orchestral solo. Even worse, is the sound of the cooling fans in two PCs at the back of the studio. I now shut those down completely when listening to serious classical music. -- Take care, Mark & Mary Ann Weiss VIDEO PRODUCTION • FILM SCANNING • DVD MASTERING • AUDIO RESTORATION Business sites at: www.dv-clips.com www.mwcomms.com www.adventuresinanimemusic.com - |
#21
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It sounds to me like these clubs of legend were driving an amp hard without properly ventilating them, so any fires or problems resulting from failure due to overheating would seem to be more the fault of the club rather than the amplifier or its designer. The owner's manual does have a mention of 'adequate ventilation.' With Series Two came cooler running temp. The old 700b was a hot box, in comparison. I've never had the fan come on during 8-ohm use. Only during 3-ohm use (three 8-ohm woofers in parallel, per channel.) I speak from experience. I worked for a touring sound company that used Phase Linear 200's, 400's and 700's exclusively into the 90's. Yes, we had amps fail but rarely in the manner of the 'Flame Linear' legend, more due to thin sheet metal chassis coming apart because they weren't designed for touring use or stagehands pushing transistor covers onto transistors between the fins of heat sinks and causing shorts or bad power blowing fuses. With about 35 Phase Linear amps we'd have maybe four channel failures a year due to causes not related to operator error, and we worked 'em hard. We had many more problems related to band engineers who associated distortion with loudness and stagehands who think they're airline baggage handlers. Amps these days are loaded with protection circuits the PL's didn't have and designers have much better simulation tools available, Carver did an excellent job given the era he did it in. The tricky part is that the D-500 is DC coupled from input to output (and has zero measurable offset in the output--quite an achievement!) Use of infrasonic filtering is strongly recommended. I used my D-500 to drive midrange and high frequency bands nowadays. To avoid clipping, a loudspeaker management system is a good idea, one with a limiter and dynamic EQ. The amp still sounds phenomenally-good today, and even better than in 1978, because of improvements I've made to the wiring and power supplies. We'd modified them to some extent, putting in B+/B- fuses on the front panel for each channel, unbolting the transformer from the chassis and bolting it to the rack, installing a support for the supply filter caps, adding 1/4" connectors in place of the RCA's, putting fans and vents in the racks. They were reliable workhorses that gave us few problems. Considering their peers (other big amps available in the late 70's) if you were smarter than the amp (a lot to ask, I know) they were great. Another great modification is to get rid of that limiter/clipper circuit in the driver stage. Instant doubling of useable unclipped power into 8-ohms. But beware your speakers. Unless it can stand being plugged directly into a 120 vac wall outlet, it's not a good idea to connect it to this amplifier. :-) The advent of 4" voice coils and ferrofluid coolants do wonders for midrange and tweeter drivers, which are capable of amazing SPL levels when coupled with the D-500. -- Take care, Mark & Mary Ann Weiss VIDEO PRODUCTION . FILM SCANNING . DVD MASTERING . AUDIO RESTORATION Business sites at: www.dv-clips.com www.mwcomms.com www.adventuresinanimemusic.com - |
#22
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Unless there are still patents applicable to this amp, perhaps someone
should do a kit for DIY duplication-what's Carver going to do, it's a 1978 design. Or even a good DIY article. Personally I like to build tube amps, but a good Class B solid state design available (besides Randy Slone's Doug Self clone) to DIYers would be good for the guy wanting it for 'pro' sound, MI, or maybe a ham wanting to build a plate modulated AM rig-or maybe even a not for profit broadcaster wanting to convert, say, a Harris BC-1 to solid state mod. |
#23
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Mark & Mary Ann Weiss wrote:
And yes, I wanted unclipped reproduction at levels exceeding 130dB. To solve what problem? dual woofer array. I once did a pink noise test with 2 v RMS reading at the speaker connection terminals using an HP 400E RMS voltmeter and took SPL readings of 112dB at 4'. I hope you used ear protection. Kind regards Peter Larsen -- ******************************************* * My site is at: http://www.muyiovatki.dk * ******************************************* |
#24
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And yes, I wanted unclipped reproduction at levels exceeding 130dB. To solve what problem? Realistic reproduction of anything that I choose to play, whether it be fireworks, or a loud rock concert, or the cannon shots in Telarc's "1812" Overture. Not many people are acutely aware of the fact that not only can you feel bass frequencies, but you can also feel midrange frequencies, if they are loud enough. Listening with earplugs is quite a different experience, with sound coming into the ear via bone conduction. It's a personal fettish with me, hence, a friend coined a title "Bass Pig" for me in 1989, because of the fourteen 18" woofers in the system. dual woofer array. I once did a pink noise test with 2 v RMS reading at the speaker connection terminals using an HP 400E RMS voltmeter and took SPL readings of 112dB at 4'. I hope you used ear protection. Kind regards Peter Larsen Certainly, when testing in the sensitive portion of the hearing range. The concern becomes more complicated for frequencies below 20 hertz, as ear protection alone is not enough. But the sensitivity testing was what I consider low level and short duration. Certainly, great care is taken when choosing programming and when testing, especially in the frequency ranges prone to causing ear damage, as the SPLs achievable can instantly do permanent hearing damage. -- Take care, Mark & Mary Ann Weiss VIDEO PRODUCTION . FILM SCANNING . DVD MASTERING . AUDIO RESTORATION Business sites at: www.dv-clips.com www.mwcomms.com www.adventuresinanimemusic.com - |
#25
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"Mark & Mary Ann Weiss" wrote in
nk.net: And yes, I wanted unclipped reproduction at levels exceeding 130dB. To solve what problem? Realistic reproduction of anything that I choose to play, whether it be fireworks, or a loud rock concert, or the cannon shots in Telarc's "1812" Overture. Not many people are acutely aware of the fact that not only can you feel bass frequencies, but you can also feel midrange frequencies, if they are loud enough. Listening with earplugs is quite a different experience, with sound coming into the ear via bone conduction. It's a personal fettish with me, hence, a friend coined a title "Bass Pig" for me in 1989, because of the fourteen 18" woofers in the system. dual woofer array. I once did a pink noise test with 2 v RMS reading at the speaker connection terminals using an HP 400E RMS voltmeter and took SPL readings of 112dB at 4'. I hope you used ear protection. Kind regards Peter Larsen Certainly, when testing in the sensitive portion of the hearing range. The concern becomes more complicated for frequencies below 20 hertz, as ear protection alone is not enough. But the sensitivity testing was what I consider low level and short duration. Certainly, great care is taken when choosing programming and when testing, especially in the frequency ranges prone to causing ear damage, as the SPLs achievable can instantly do permanent hearing damage. -- Take care, Mark & Mary Ann Weiss And I thought I was pretty hard core with 500+ watts per channel into 87 db 1w/m sensitivity. I am still in the junior leagues apparantly. My stuff gets loud enought to cause my ears to intermodulate. Had that happen once at a concert featuring the Atlanta Symphony and Chorus. r -- Nothing beats the bandwidth of a station wagon filled with DLT tapes. |
#26
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And I thought I was pretty hard core with 500+ watts per channel into 87 db 1w/m sensitivity. I am still in the junior leagues apparantly. My stuff gets loud enought to cause my ears to intermodulate. Had that happen once at a concert featuring the Atlanta Symphony and Chorus. r Everyone has their tastes. Mine grew from pipe organs and living next to neighbors who were a rock band. Also a help was a wealthy family friend who had a penchant for very loud and clean sound reproduction. He owns a JBL Paragon and a bunch of Cerwin-Vega speakers. I was never impressed with the bass though. 'Couldn't find it in any commercially-made speakers, so I made my own. Over the course of 20 years, I built ten different speaker setups, in persuit of the ellusive "loud & accurate" sound. Horn-loaded systems littered my basement for the first 15 years, stacks of Community horns and drivers, hand-built folded horns of all sizes... never liked the sound. So I ended up converting to all planar drivers and adding more of them and carefully-selecting them. Thanks to a very patient owner of a sound equipment shop in the state, I was able to try and exchange a variety of drivers, enabling me to make A/B/C comparisons of tweeters, midrange drivers and woofers. I separated the hype from the performance and picked what did the job for my purposes. By 1984, I had assembled, what has remained my 'ultimate' sound system. And when digital music came along, it sounded even more dynamic. Right now, my ultimate listening experience comes directly off my musical instruments--bypassing the recording studios and the compression to 16-bit digital CDs. A bunch of Kurzweil sampler/synthesizers, direct into the sound system... no compression, no rolloff on the bass, no lost impact. Ooooh, what an experience. :-) I await my chance to record a local symphony orchestra with my MOTU 896 in beautiful 24/96 digital, with a -114dB noise floor. That should be interesting. -- Take care, Mark & Mary Ann Weiss VIDEO PRODUCTION • FILM SCANNING • DVD MASTERING • AUDIO RESTORATION Business sites at: www.dv-clips.com www.mwcomms.com www.adventuresinanimemusic.com - |
#27
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Mark & Mary Ann Weiss wrote: I await my chance to record a local symphony orchestra with my MOTU 896 in beautiful 24/96 digital, with a -114dB noise floor. That should be interesting. I take it that you haven't looked very carefully at the dynamic range of live recordings. No matter what modern technology you use to record , the dynamic range of the recording is not so much limited by the recording technology, as things like the background noise level of the room, and the spurious human noises made by large numbers of humans playing musical instruments and listening to the same. |
#28
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"Arny Krueger" wrote in message ps.com... Mark & Mary Ann Weiss wrote: I await my chance to record a local symphony orchestra with my MOTU 896 in beautiful 24/96 digital, with a -114dB noise floor. That should be interesting. I take it that you haven't looked very carefully at the dynamic range of live recordings. No matter what modern technology you use to record , the dynamic range of the recording is not so much limited by the recording technology, as things like the background noise level of the room, and the spurious human noises made by large numbers of humans playing musical instruments and listening to the same. Some venues are pretty quiet, and in between the crowd coughs, rustles and other noises, I can hear the hiss of the mixing equipment used in a lot of recordings. Worse than that, there has been an increasing trend toward using dynamic compression on digital recordings, ruining the impact of the original performance. I recently did a 5.1 channel DVD of a cultural event, and despite the HVAC rumble, I had a palpable sense of "being there" because nothing came between me and the sounds of the event. -- Take care, Mark & Mary Ann Weiss VIDEO PRODUCTION . FILM SCANNING . DVD MASTERING . AUDIO RESTORATION Business sites at: www.dv-clips.com www.mwcomms.com www.adventuresinanimemusic.com - |
#29
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"Mark & Mary Ann Weiss" wrote in news:MiJAd.2353
: I await my chance to record a local symphony orchestra with my MOTU 896 in beautiful 24/96 digital, with a -114dB noise floor. That should be interesting. -- Take care, Mark & Mary Ann Weiss I would love to have a recording like that. When are you going to make the recording? r |
#30
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I await my chance to record a local symphony orchestra with my MOTU 896 in beautiful 24/96 digital, with a -114dB noise floor. That should be interesting. -- Take care, Mark & Mary Ann Weiss I would love to have a recording like that. When are you going to make the recording? r I'm still waiting for approval from the orchestra chair. Could be sometime this spring, if things go as I would like. The staff likes the idea of a promotional video with 5.1 ch surround sound, but as with any professional orchestra, there are legal issues that have to be sorted out carefully first. Maybe I'll try to get into recording some pipe organs in the meantime, although there are few cathedrals around here with a real pipe organ, let alone one with 32' pedal stops. -- Take care, Mark & Mary Ann Weiss VIDEO PRODUCTION • FILM SCANNING • DVD MASTERING • AUDIO RESTORATION Business sites at: www.dv-clips.com www.mwcomms.com www.adventuresinanimemusic.com - |
#31
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Mark & Mary Ann Weiss wrote:
I'm still waiting for approval from the orchestra chair. Fewer people have to agree on a permission if you aim for chamber music and the actual dynamic range may be larger than the one of a full orchestra. Mark & Mary Ann Weiss Kind regards Peter Larsen -- ******************************************* * My site is at: http://www.muyiovatki.dk * ******************************************* |
#32
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Peter Larsen wrote in
: Mark & Mary Ann Weiss wrote: I'm still waiting for approval from the orchestra chair. Fewer people have to agree on a permission if you aim for chamber music and the actual dynamic range may be larger than the one of a full orchestra. That certainly does depend on program material. A Symphony could have a huge dynamic range that would make a string quartet sound quite anemic. A few pieces by Chabrier come to mind. There are many more of course. r -- Nothing beats the bandwidth of a station wagon filled with DLT tapes. |
#33
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R wrote:
Fewer people have to agree on a permission if you aim for chamber music and the actual dynamic range may be larger than the one of a full orchestra. That certainly does depend on program material. A Symphony could have a huge dynamic range that would make a string quartet sound quite anemic. First the general point: a chamber music event is able to contain near silence, a symphone orchestra event is not, there are more clothes rustling and people moving in chairs and more people on stage - and usually also in the hall - breathing. The peak SPL - as seen from the mic position - of a chamber music event is the peak SPL of a violin, flute or concert grand, all of which can be quite loud, alternatively in case of omni mics the peak SPL generated by the applause. A few pieces by Chabrier come to mind. Or Takemitsu, or ... or .... There are many more of course. On your second reading of my post you may notice the use of the wording "could" rather than "will", this to allow for the exceptions. Dynamic range per se is not about total loudness, it is about the difference between audience holding their breath in expectative silence after the sign from the concert master and the FFF. It takes unamplified avantgarde jazzical to really beat chamber music in that regard. r Kind regards Peter Larsen -- ******************************************* * My site is at: http://www.muyiovatki.dk * ******************************************* |
#34
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I'm still waiting for approval from the orchestra chair. Fewer people have to agree on a permission if you aim for chamber music and the actual dynamic range may be larger than the one of a full orchestra. While that's true, the circumstances are that I have a business relationship in place with a particular symphony orchestra, and since I know of no chamber music groups in the area, I'm working on the lead that I have. Given the fact that the regional and local symphonies are starving, it would seem in their best interest to get a promotional produced piece for themselves. -- Best Regards, Mark A. Weiss, P.E. www.mwcomms.com - |
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