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#1
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The simplest amplifier
I want to amplify the main outs of my Mackie 1202VLZ Pro
into my current Energy stereo speakers, and eventually a nice set of monitors. My main concern is getting an amp that is as accurate and transparent as possible. It should deliver 25 to 100 watts for small room listening. I envision it with a single ergonomic knob that controls volume, and that's it. I could see spending $200 on it if I thought it was made to last decades, and was going to be able to give me very high quality amplification. Now, I have my recording room speakers, but I'd also like to use my DAW to provide music to an adjoining room, and an outside speaker pair. I could see having multiple speaker outs that are switchable. Other than that, perhaps I would want a separate amp for each in order to control the volume on each pair separately. I'm not sure. Thanks, Tobiah |
#2
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The simplest amplifier
Tobiah wrote:
I want to amplify the main outs of my Mackie 1202VLZ Pro into my current Energy stereo speakers, and eventually a nice set of monitors. My main concern is getting an amp that is as accurate and transparent as possible. It should deliver 25 to 100 watts for small room listening. I use a very nice cambridge poweramp, something 2 X "50" for just that, from the size of the the powersupply it is a 2X40, but the specs say more. I envision it with a single ergonomic knob that controls volume, and that's it. You just need say a three step attenuator, something like -15, -20 and -25 dB, that should put you sufficiently in the ballpark for regularing listening level from the Mackie. I could see spending $200 on it if I thought it was made to last decades, and was going to be able to give me very high quality amplification. Now, I have my recording room speakers, but I'd also like to use my DAW to provide music to an adjoining room, and an outside speaker pair. I could see having multiple speaker outs that are switchable. Other than that, perhaps I would want a separate amp for each in order to control the volume on each pair separately. I'm not sure. A NAD 906 multichannel amp comes to mind then, you can bridge two pairs for 2 x "100" and use one pair for adjoining, or simply use one channel pair for each set, must be available 2'hand on some garage sale. It contains 3 times the poweramp from the NAD302, but that same poweramp seems to me to sound better re-packaged, and better even when bridged. Nice heavy thing .... seems like it has a real psu. Tobiah Kind regards Peter Larsen |
#3
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The simplest amplifier
Tobiah writes:
I want to amplify the main outs of my Mackie 1202VLZ Pro into my current Energy stereo speakers, and eventually a nice set of monitors. My main concern is getting an amp that is as accurate and transparent as possible. It should deliver 25 to 100 watts for small room listening. I envision it with a single ergonomic knob that controls volume, and that's it. I could see spending $200 on it if I thought it was made to last decades, and was going to be able to give me very high quality amplification. Now, I have my recording room speakers, but I'd also like to use my DAW to provide music to an adjoining room, and an outside speaker pair. I could see having multiple speaker outs that are switchable. Other than that, perhaps I would want a separate amp for each in order to control the volume Most of us always want less for more, but it seems you're pushing the envelope on those parameters of cheap/decades-reliable/transparent. At $200, you can probably only really get the first one; maybe a hint at the third, but likely just a hint. Certainly "decades reliable" is out the window, mainly because of the really, really crap parts you'll find at that price point. (Try 3-5 years, with a bit of luck.) A Bryston gets you a 20 year warranty, and their 2B or 3B models are in that power range, but be prepared to spend well north of US$1200.00, even used. The newer series Brystons even sound pretty good, as they did some smart things in the VAS when that series was redesigned a number of years ago. There are some fairly good pro-sumer amps in the $500 range that will get you a little closer to sound and reliability ideals. Now, it's easy to start a holy war here on sonic quality, but IMHO Class-A will get you uber transparancy, if properly applied. Pass Labs comes to mind, but now you're north of $2K, $3K, even $4K (not to mention the heat generation and power consumption issues). And while cheap amps have the potential to "sound better" than similar amps did 20-30 years ago, remember that a power amp is essentially a modulated power supply. Good power supplies simply cost money for a laundry list of reasons, often relating to many aspects of: "Ah kinna change the laws of physics, Captain" (Lt. Cmd Scott to Captain Kirk, more than once). But, it'll be interesting to see what people have to say. Good luck with it, Frank Mobile Audio -- |
#4
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The simplest amplifier
Tobiah wrote:
I envision it with a single ergonomic knob that controls volume, and that's it. You just need say a three step attenuator, something like -15, -20 and -25 dB, that should put you sufficiently in the ballpark for regularing listening level from the Mackie. Oh, so your amp has not even a volume knob? Still, wouldn't I be able to control the volume ok from the Mackie? Why would I need the attenuator? Amp sensitivity for full output power is usually in the 1 volt range, your mackie will have a max output in the 8 volt range. So if you do NOT put an inline attenuator of some type in between you will risk to blow up eardrums, cochlea and less important loudspeakers or drive units thereof, the latter are replaceable, but your sense of hearing, especially the cochlea, is not. I don't know the efficiency of your loudspeakers, so I can't tell you exactly what to main for, but the relevant attenuation is in the 20 dB range +/- perhaps 8 dB. As example: I use 12 dB fixed attenuation to match household sized amplifier to midiman sound card. Poweramplifiers for use in a diy household should always be atttenuated enough to allow not2worry hotplugging ... at least of those that are not connected directly to mid and/or treble units. Another "oldie" amp model to look for is the Rotel RB960-BX, but frankly the NAD906 is cleaner sounding, the issue with the Rotel may be the opamp stage that allows bridging, but I never bothered investigating. I like it a lot, it is just that I was so pleasantly surprised when listning to the 906 in bridging mode yesterday. It has input level adjustment. It has been unused for a couple of years and the reason I turned it on was to check whether it should be considered junk or "for repair", I took it out of use as amp for a small active three-way because the treble channel pair suddenly got very hot. I never did investigate whether it was the amp or the cross-over, but I just got me some alternative opamps for that cross-over, an old IFM. If it had been the poweramp I reckon that channel pair hadn't worked when I finally checked it. I may have confused you and your mileage may vary wildly. Kind regards Peter Larsen |
#5
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The simplest amplifier
On Mon, 18 Jul 2011 16:42:54 GMT, Tobiah wrote:
I want to amplify the main outs of my Mackie 1202VLZ Pro into my current Energy stereo speakers, and eventually a nice set of monitors. My main concern is getting an amp that is as accurate and transparent as possible. It should deliver 25 to 100 watts for small room listening. I envision it with a single ergonomic knob that controls volume, and that's it. I could see spending $200 on it if I thought it was made to last decades, and was going to be able to give me very high quality amplification. Now, I have my recording room speakers, but I'd also like to use my DAW to provide music to an adjoining room, and an outside speaker pair. I could see having multiple speaker outs that are switchable. Other than that, perhaps I would want a separate amp for each in order to control the volume on each pair separately. I'm not sure. Thanks, Tobiah Uh, Archer, Realistic? |
#6
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The simplest amplifier
I envision it with a single ergonomic knob that controls volume, and
that's it. You just need say a three step attenuator, something like -15, -20 and -25 dB, that should put you sufficiently in the ballpark for regularing listening level from the Mackie. Oh, so your amp has not even a volume knob? Still, wouldn't I be able to control the volume ok from the Mackie? Why would I need the attenuator? |
#7
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The simplest amplifier
Most of us always want less for more, but it seems you're pushing the envelope on those parameters of cheap/decades-reliable/transparent. At $200, you can probably only really get the first one; maybe a hint at the third, but likely just a hint. I see home theater receivers going for around $500, and they seem to do a lot of stuff. I don't know anything about home theater. I was just thinking that if all I wanted was an amp only, that it would be quite a bit cheaper. Right now, I'm using a class-a JVC receiver from the 80's. Maybe it's fine for what I'm doing. I thought it would be nice to cut out the radio receiver, and equalizer, and phono input and tape monitor etc. and get down to a decent amplifier-only that might end up sounding better. It is quite possible that I won't be able to tell the difference in sound anyway. If so, I would still consider a new amp if I could get one that was substantially smaller than the JVC, which has a much larger footprint than the 1202. Tobiah |
#8
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The simplest amplifier
Amp sensitivity for full output power is usually in the 1 volt range,
your mackie will have a max output in the 8 volt range. So couldn't I promise not to turn the Mackie up very far? What equipment then, are they expecting a person to hook up to that amp? I noticed that many amps accept the XLR inputs, which the Mackie has outputs for. Would such a connection solve the level problems? Thanks, Toby |
#9
Posted to rec.audio.pro
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The simplest amplifier
In article , Tobiah wrote:
I want to amplify the main outs of my Mackie 1202VLZ Pro into my current Energy stereo speakers, and eventually a nice set of monitors. My main concern is getting an amp that is as accurate and transparent as possible. It should deliver 25 to 100 watts for small room listening. I envision it with a single ergonomic knob that controls volume, and that's it. I could see spending $200 on it if I thought it was made to last decades, and was going to be able to give me very high quality amplification. Buy a used Adcom GFA 535. Add a volume control. --scott -- "C'est un Nagra. C'est suisse, et tres, tres precis." |
#11
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The simplest amplifier
I envision it with a single ergonomic knob that controls
volume, and that's it. *I could see spending $200 on it if I thought it was made to last decades, and was going to be able to give me very high quality amplification. Tobiah I have used, since God was a boy, a Quad 303 ..... bought new ... serviced twice in its life and is probably the best studio amp I have ever used .... I power my studio NS10's with it and have a switched A .... B and A&B unit which adds in Kef Correlli speakers .... altogether the best near field situation I have heard. It is interesting to realise that the mainstay of all BBC studio audience speakers [no matter what venue] in the 60's, 70's was the Quad 303 ... that is why I bought mine. Built like a brick [and looks like one] no volume control or EQ ... just an amp. I added a simple wall mounted volume control which acts as a main system attenuator ... and acts as a simple on/off for recording with earphones. I should imagine they are easily and cheaply available on Ebay? Dec [Cluskey] http://www.deccluskey.co.uk/blog |
#12
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The simplest amplifier
"Soundhaspriority" writes:
"Tobiah" wrote in message ... beast. -snips- Right now, I'm using a class-a JVC receiver from the 80's. Maybe it's fine for what I'm doing. If you have a Class-A amp from the 80's, stick with it. You can't replace it at reasonable cost. I'd be surprised that anything labeled a "receiver" is actually class-A. Can you tell us where you saw the "Class A" label on this unit, and in what context? Does it put out LOTS of heat, even with no signal present? Note that "class A" might be some sort of quality rating from the manufacturer's marketing department, and not the actual topology of the power amp circuits. It's possible too that the preamp and line-level signal paths are class A, but it's still more than likely that the power amp sections are AB. If the power amp section truly is class-A, Bob is right -- hang onto that beast. Be aware, though, that at 25 years you're at or perhaps past the useful life of the electrolytic caps in the unit, particularly the PS caps. (Any hum? Does it sound weak in the low end?) The unit might well be worth re-capping if it's a good design and good build quality. Frank Mobile Audio -- |
#13
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The simplest amplifier
Harry Trueman wrote:
I picked up a Sampson F800 (1200 bridged) to run from the cheapo Yamaha and the master slider works quite nicely. That is to say that I would have to "try" to blow the speakers or cochlea. Audio tapered slider maybe? Clean as a whistle. Try and do an A-B between the Samson and a cleaner amplifier like the Adcom, especially at very low power levels. You'll be surprised. --scott -- "C'est un Nagra. C'est suisse, et tres, tres precis." |
#14
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The simplest amplifier
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#15
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The simplest amplifier
"Tobiah" wrote in message ... Amp sensitivity for full output power is usually in the 1 volt range, your mackie will have a max output in the 8 volt range. So couldn't I promise not to turn the Mackie up very far? The S/N ratio will be lower if you simply turn the Mackie down, an attenuator reduces both the signal and noise. Trevor. |
#16
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The simplest amplifier
That might be the way for him to go. Good quality, cheap. If you don't mind risking, "No returns accepted". |
#17
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The simplest amplifier
Tobiah wrote:
Amp sensitivity for full output power is usually in the 1 volt range, your mackie will have a max output in the 8 volt range. So couldn't I promise not to turn the Mackie up very far? What equipment then, are they expecting a person to hook up to that amp? Household variety preamp. With those extra input attenuation is wise as well. I noticed that many amps accept the XLR inputs, which the Mackie has outputs for. Would such a connection solve the level problems? No. A poweramplifier with an input level control would, that applies btw. to the NAD 906. Thanks, You're welcome. Toby Kind regards Peter Larsen |
#18
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The simplest amplifier
Harry Trueman wrote:
[the quest for the poweramp] Buy a used Adcom GFA 535. Add a volume control. --scott I picked up a Sampson F800 (1200 bridged) to run from the cheapo Yamaha and the master slider works quite nicely. That is to say that I would have to "try" to blow the speakers or cochlea. Audio tapered slider maybe? Clean as a whistle. You missed the barn by a furlong, suggested amplifier - just as the one Scott suggested - does not have an input level control. Kind regards Peter Larsen |
#19
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The simplest amplifier
Frank Stearns wrote:
"Soundhaspriority" writes: "Tobiah" wrote in message ... beast. -snips- Right now, I'm using a class-a JVC receiver from the 80's. Maybe it's fine for what I'm doing. If you have a Class-A amp from the 80's, stick with it. You can't replace it at reasonable cost. I'd be surprised that anything labeled a "receiver" is actually class-A. Can you tell us where you saw the "Class A" label on this unit, and in what context? It is a "new class a" amp, they were de la mode in the 1980'es, and can be quite sweet sounding, I'm using a two for compression driver powering, they are great at not delivering power. Be aware, though, that at 25 years you're at or perhaps past the useful life of the electrolytic caps in the unit, particularly the PS caps. (Any hum? Does it sound weak in the low end?) Yes, my old Radford STA25's manual said 17 years life expectancy, but it is probably still running fine with its new owner since 1980. I still miss it sometimes ... The unit might well be worth re-capping if it's a good design and good build quality. Amps that are frequently powered up and used at household operating temperatures tend to last very well, what is bad is to leave them unused and forget to power the up for a week say once every 6 to 12 months. Frank Mobile Audio Kind regards Peter Larsen |
#20
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The simplest amplifier
Trevor wrote:
"Tobiah" wrote in message ... Amp sensitivity for full output power is usually in the 1 volt range, your mackie will have a max output in the 8 volt range. So couldn't I promise not to turn the Mackie up very far? The S/N ratio will be lower if you simply turn the Mackie down, an attenuator reduces both the signal and noise. Did you forget a "than" between "lower" and "if"? Trevor Kind regards Peter Larsen |
#21
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The simplest amplifier
"Peter Larsen" wrote in message k... Amp sensitivity for full output power is usually in the 1 volt range, your mackie will have a max output in the 8 volt range. So couldn't I promise not to turn the Mackie up very far? The S/N ratio will be lower if you simply turn the Mackie down, an attenuator reduces both the signal and noise. Did you forget a "than" between "lower" and "if"? Nope, overall S/N ratio will be lower (noise will be higher) if you simply turn the Mackie output down while leaving the power amp gain at maximum. How much difference is another matter entirely :-) Trevor. |
#22
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The simplest amplifier
Harry Trueman wrote:
OK, I guess I know what you're "driving " at. The board I'm using is actually a multitrack with a comsumer output of only .775mv @ 0db for typical line level out. If his Mackie is a 8v-10v out then he might blow out a window in the process of absent mindedly hot swapping inputs with anything like an 800w samson. The consequences of hotplugging something that does not establish ground first depend on input sensitivity rather than on output from whatever is in the other end of the wire. That's why I like the 800w I guess (headroom?). Headroom is nice, but it is not nice to have loudspeaker damage, I repaired a cross-over for a friend with a pair of Kenwood L07's - he was lucky, the accidental hotplugging he did only caused a 7 watt ceramic midrange attenuation resistor to blow. I have accidentally left it on for days, and it's so quiet that I don't realize it's on. Don't know if I'd personally be happy with just 60 or so watts but that's just a product of me being weened on hard rock and the need to "blast" it occasionally . Comments not possible, I don't know the effiency of your loudspeakers nor the size of your listening room and your listening distance. He suggests I think that he wants to be able to control the volume on the remote sets of speakers so he could always add another amp, also with attenuator, later on using the additional outputs on the Mackie or just use the JVC receiver for that, if it's not one of those home theater things. No? Why not get three stereo amplifiers in one box then, Rotel also makes/made one, also a very good amp. And that one has attenuators on the front. It is a wonderful amp to have when comparing loudspeakers. I could see spending $200 on it if I thought it was made to last decades, and was going to be able to give me very high quality amplification. Good luck with that. I've always wanted an active tri-amp configuration for $200 because I'm not Donald Trump and it has 8X the transit response as passive at equal wattage....but The example product, the NAD 906 must have been in the USD 350 range new in 1997. That would imply a second hand price below USD 200 now. The 6 channel Rotel, also three stereo amps in one box, ought to also be reasonably priced, mine cost me the equivalent of USD 275 a couple of years ago. I find it easy to believe that the Adcom suggested by Scott is a possibly better choice, as is the additional headroom from the Behringer Arny suggested. Horses for courses and it is the OP who knows his quality and power-requirements best but quality beats power in most home listening context just as power beats quality in most PA contexts because a larger amp that does not clip sounds sweeter than a smaller one that does. The Yamaha P1600 is btw. a very good amplifier, it is from the pa range so it does have a fan but it is modestly noisy and has clarity as well as punch and is not "toy class". An Ebay search including expired auctions may be a good way to find the pricerange for something. Kind regards Peter Larsen |
#23
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The simplest amplifier
"Tobiah" wrote in message ... Amp sensitivity for full output power is usually in the 1 volt range, your mackie will have a max output in the 8 volt range. So couldn't I promise not to turn the Mackie up very far? What equipment then, are they expecting a person to hook up to that amp? I noticed that many amps accept the XLR inputs, which the Mackie has outputs for. Would such a connection solve the level problems? No. Balanced XLR inputs have the effect of doubling the amp's sensitivity as compared to unbalanced.RCAs. Many consoles have control room outputs that may have a more favorable level situation. Or, you just use a power amp with input attenuators and turn the attenuators down and keep them there. BTW my choice for this application would be an amp that I have several years of experience with - the Behringer A500. It's a rotten 500 watt amp, but a very nice 200-250 watt amp @ 100-125 wpc. |
#24
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The simplest amplifier
On Tue, 19 Jul 2011 06:07:30 +0100, "Peter Larsen"
wrote: Harry Trueman wrote: [the quest for the poweramp] Buy a used Adcom GFA 535. Add a volume control. --scott I picked up a Sampson F800 (1200 bridged) to run from the cheapo Yamaha and the master slider works quite nicely. That is to say that I would have to "try" to blow the speakers or cochlea. Audio tapered slider maybe? Clean as a whistle. You missed the barn by a furlong, suggested amplifier - just as the one Scott suggested - does not have an input level control. Kind regards Peter Larsen OK, I guess I know what you're "driving " at. The board I'm using is actually a multitrack with a comsumer output of only .775mv @ 0db for typical line level out. If his Mackie is a 8v-10v out then he might blow out a window in the process of absent mindedly hot swapping inputs with anything like an 800w samson. That's why I like the 800w I guess (headroom?). I have accidentally left it on for days, and it's so quiet that I don't realize it's on. Don't know if I'd personally be happy with just 60 or so watts but that's just a product of me being weened on hard rock and the need to "blast" it occasionally . He suggests I think that he wants to be able to control the volume on the remote sets of speakers so he could always add another amp, also with attenuator, later on using the additional outputs on the Mackie or just use the JVC receiver for that, if it's not one of those home theater things. No? I could see spending $200 on it if I thought it was made to last decades, and was going to be able to give me very high quality amplification. Good luck with that. I've always wanted an active tri-amp configuration for $200 because I'm not Donald Trump and it has 8X the transit response as passive at equal wattage....but |
#25
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The simplest amplifier
On Tue, 19 Jul 2011 12:14:02 +0200, Peter Larsen
wrote: Harry Trueman wrote: Kind regards Peter Larsen The consequences of hotplugging something that does not establish ground first depends on input sensitivity rather than on output from whatever is in the other end of the wire. Who said anything about establishing ground? I might do this when I absent mindedly plug the drum machine back into channels 7/8 without checking the faders first. I am just guessing that the OP is recording tracks and using his mackie and monitors to do his craft to later listen in a remote environment. Headroom is nice, but it is not nice to have loudspeaker damage, I repaired a cross-over for a friend with a pair of Kenwood L07's - he was lucky, the accidental hotplugging he did only caused a 7 watt ceramic midrange attenuation resistor to blow. Thanks for sharing that. I have a silly philosophy that I've always used over powerful amps to allow the amp to take control of the physical aspects of the speaker. Not the other way around. In otherwords, having the faders set at 2-3 as opposed to 8-0 produces a better quality output. I've "never" blown a speaker. Really! We did let Blackfoot use our PA one night and they did blow the monitor speakers after which they prompty reimbursed us full cost without us asking. We also let the Little River Band use our PA and they remarked how good it sounded (unbelieveable 5 part vocals those chaps have) Comments not possible, I don't know the effiency of your loudspeakers nor the size of your listening room and your listening distance. I would think that if you did, you'd be spying on me...LOL. But I'm using 3 way Pioneers with 15", Altec Lansing 83's which I occasionally switch with JBL D38 Decade (or is it decayed?) speakers as I have 4 sets. I don't have access to NS10's so. These el cheapo's are fine with me. The last system we used was 12,000 watts of Crest, Carver tri-amp w/JBL drivers. This is the system "Little Liver Band" at a party used (typo intentional) with 4 stacks on each side was enough to blast RFK stadium and get the Redskin cheerleaders gyrating the drummer out of his throne. The sound on this system was so crisp, fine and quiet that you could see the audio. Why not get three stereo amplifiers in one box then, Rotel also makes/made one, also a very good amp. And that one has attenuators on the front. It is a wonderful amp to have when comparing loudspeakers. On your suggestion, he should look at this also. |
#26
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The simplest amplifier
In article ,
Harry Trueman wrote: On 18 Jul 2011 21:34:34 -0400, (Scott Dorsey) wrote: Harry Trueman wrote: I picked up a Sampson F800 (1200 bridged) to run from the cheapo Yamaha and the master slider works quite nicely. That is to say that I would have to "try" to blow the speakers or cochlea. Audio tapered slider maybe? Clean as a whistle. Try and do an A-B between the Samson and a cleaner amplifier like the Adcom, especially at very low power levels. You'll be surprised. I believe you. Going back decades, I went from Dynaco to Phase Linear to Crown to Hafler. The amp I was most impressed with was the Crests we used for live sound reinforcement. They were "tanks". But they belonged to the band. I think I recall the Phase Linear being serviced maybe 5X. I'm quite happy with the Samson, thank you. The later Haflers aren't bad at all, and actually the cheapest line from QSC is a lot better than I'd ever expected. But nothing blows up like a Phase Linear. "I was asking a union hand at the Oakland Paramount about the last time the fire-curtain had been used. The answer: not since the sound companies stopped using Phase Linears in their racks." --T.Alan I have personally seen one of the Phase Linear 700s spewing sparks three feet in the air after the output transistors failed, at the Little Five Points Pub in Atlanta. Quality workmanship, that. They don't make them like that any more. --scott -- "C'est un Nagra. C'est suisse, et tres, tres precis." |
#28
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The simplest amplifier
Harry Trueman wrote:
As a school kid the Dynaco and Hafler kits were fun to assemble and made me think I knew something about audio electronics, which I don't. Just would whip out the Nokorode and a soldering pencil and a screwdriver and zip, I built my own Pre and Power amp. You could plug things in them like you would a 2 channel board. Later I would discover that that's not possible with a "receiver" and was disappointed much like OP. I've heard good things about QSC. But then again, back in the day they told me that Phase Linear was state of the art and I believed it. Can't believe I was so stupid as to think each time would be the last repair. Serviceman said after 3X, "This belongs in your living room, not PA". He didn't want to service it. It WAS state of the art. It got an outrageous amount of power out of a small package, and using the cheapest possible output transistors too. Nobody had ever managed that kind of power density before. However, there was a downside... PS the samson is not 1200w bridged. Apparently I read the specs for the F1200 which is in the same manual. It's 800w. Need to eat more carrots. Just like I thought the Hafler had .002% THD. Wrong again? The Samson power ratings basically come out of someone's butt in the marketing department. Try measuring FTC method with a one-third power warmup and see if it even survives the measurement... --scott -- "C'est un Nagra. C'est suisse, et tres, tres precis." |
#29
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The simplest amplifier
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#30
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The simplest amplifier
On 7/19/2011 11:14 AM, Harry Trueman wrote:
...back in the day they told me that Phase Linear was state of the art and I believed it. Can't believe I was so stupid as to think each time would be the last repair. Serviceman said after 3X, "This belongs in your living room, not PA". He didn't want to service it. They don't make them like that any more. Thank God. Yes, the main problem with Phase Linears was how they were made, a big power transformer and big supply caps hung on thin sheet metal. Then there were those sheet metal transistor covers that would short out the transistors if you bumped them or simply looked at them wrong while messing around the back of the amp. I worked with a sound company that made brackets so the transformers and caps could be bolted to the sides of the racks to take the stress off the chassis, added B+ and B- fuses to each channel and threw out the transistor covers. That increased the reliability a great deal and the fuses kept things from catching fire. They ran probably 35-40 200B's, 400B's and 700B's and had to fix maybe 1-2 a year, usually after a blown driver or rain storm. I have a couple of XPL-909's I took out of one major catastrophe. What usually happened is the output transistors would short, take out the driver stage which would burn a hole in the circuit board, hence the moniker 'Flame Linear.' Bob Heil put purple front panels on 700's and sold 'em under his name, said sound co. had a couple of those. |
#31
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The simplest amplifier
Right now, I'm using a class-a JVC receiver from the 80's. Maybe it's fine for what I'm doing. If you have a Class-A amp from the 80's, stick with it. You can't replace it at reasonable cost. I'd be surprised that anything labeled a "receiver" is actually class-A. Can you tell us where you saw the "Class A" label on this unit, and in what context? It's a JVC R-S33. It says "Super-A" on the front, but the original literature touted the unit as a "class A". A quick google search seems to suppport that it's class A - I'm not sure. Does it put out LOTS of heat, even with no signal present? Note that "class A" might be some sort of quality rating from the manufacturer's marketing department, and not the actual topology of the power amp circuits. It's possible too that the preamp and line-level signal paths are class A, but it's still more than likely that the power amp sections are AB. I wouldn't say "LOTS" of heat, no. The entire top of the unit is vented, and it does get warm. If the power amp section truly is class-A, Bob is right -- hang onto that beast. Be aware, though, that at 25 years you're at or perhaps past the useful life of the electrolytic caps in the unit, particularly the PS caps. (Any hum? Does it sound weak in the low end?) I don't notice any weakness in the sound really. I originally just thought that some modern amp-only unit might save me some desk space and through better technology, get me better (in some way) sound. Thanks, Toby |
#32
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The simplest amplifier
I'd be surprised that anything labeled a "receiver" is actually class-A. Can you tell us where you saw the "Class A" label on this unit, and in what context? It's a JVC R-S33. Â*It says "Super-A" on the front, but the original literature touted the unit as a "class A". Â*A quick google search seems to support that it's class A - I'm not sure. I found a description he http://www.canuckaudiomart.com/details/174848- jvc_rs33_stereo_receiver_original_service_manual_w ith_full_schematic_and_more Sounds to me a lot like the marketing department's description of an ordinary Class AB output stage... Well, there you are. Anyway, I was just wondering whether I could replace this thing with something smaller and simpler that would sound better, for around $200. Thanks, Tobiah |
#33
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The simplest amplifier
Tobiah wrote:
I'd be surprised that anything labeled a "receiver" is actually class-A. Can you tell us where you saw the "Class A" label on this unit, and in what context? It's a JVC R-S33. Â*It says "Super-A" on the front, but the original literature touted the unit as a "class A". Â*A quick google search seems to support that it's class A - I'm not sure. I found a description he http://www.canuckaudiomart.com/details/174848- jvc_rs33_stereo_receiver_original_service_manual_ with_full_schematic_and_more Sounds to me a lot like the marketing department's description of an ordinary Class AB output stage... Well, there you are. Anyway, I was just wondering whether I could replace this thing with something smaller and simpler that would sound better, for around $200. Yes. Try a used GFA-535, as I said earlier. There are some of the 535s that were shipped with a volume control option, but most of the used ones will be fixed gain. --scott -- "C'est un Nagra. C'est suisse, et tres, tres precis." |
#34
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The simplest amplifier
"Scott Dorsey" wrote in message
... Tobiah wrote: I'd be surprised that anything labeled a "receiver" is actually class-A. Can you tell us where you saw the "Class A" label on this unit, and in what context? It's a JVC R-S33. Â It says "Super-A" on the front, but the original literature touted the unit as a "class A". Â A quick google search seems to support that it's class A - I'm not sure. I found a description he http://www.canuckaudiomart.com/details/174848- jvc_rs33_stereo_receiver_original_service_manual _with_full_schematic_and_more Sounds to me a lot like the marketing department's description of an ordinary Class AB output stage... Well, there you are. Anyway, I was just wondering whether I could replace this thing with something smaller and simpler that would sound better, for around $200. Yes. Try a used GFA-535, as I said earlier. There are some of the 535s that were shipped with a volume control option, but most of the used ones will be fixed gain. --scott -- "C'est un Nagra. C'est suisse, et tres, tres precis." GFA 535s have been selling on Ebay from $60 to $120 each. That should meet your budget. Steve King |
#35
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The simplest amplifier
On 20/07/2011 12:28 AM, Scott Dorsey wrote:
In article , Harry Trueman wrote: On 18 Jul 2011 21:34:34 -0400, (Scott Dorsey) wrote: Harry Trueman wrote: I picked up a Sampson F800 (1200 bridged) to run from the cheapo Yamaha and the master slider works quite nicely. That is to say that I would have to "try" to blow the speakers or cochlea. Audio tapered slider maybe? Clean as a whistle. Try and do an A-B between the Samson and a cleaner amplifier like the Adcom, especially at very low power levels. You'll be surprised. I believe you. Going back decades, I went from Dynaco to Phase Linear to Crown to Hafler. The amp I was most impressed with was the Crests we used for live sound reinforcement. They were "tanks". But they belonged to the band. I think I recall the Phase Linear being serviced maybe 5X. I'm quite happy with the Samson, thank you. The later Haflers aren't bad at all, and actually the cheapest line from QSC is a lot better than I'd ever expected. But nothing blows up like a Phase Linear. "I was asking a union hand at the Oakland Paramount about the last time the fire-curtain had been used. The answer: not since the sound companies stopped using Phase Linears in their racks." --T.Alan I have personally seen one of the Phase Linear 700s spewing sparks three feet in the air after the output transistors failed, at the Little Five Points Pub in Atlanta. Quality workmanship, that. They don't make them like that any more. --scott Likewise. Back in the 70's I saw two LF horn enclosures catch on fire after the fans in the PL700's stopped. Sound was immaterial once the crowd realised we had a pyrotechnics show as well |
#36
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The simplest amplifier
Trevor wrote:
Right, looks like a straight forward description of class AB. Obviously NOT class A. My understanding is that they are using a dynamic bias rather than a fixed bias in the "new class a" ploys. Trevor Kind regards Peter Larsen |
#37
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The simplest amplifier
"Peter Larsen" wrote in message k... Right, looks like a straight forward description of class AB. Obviously NOT class A. My understanding is that they are using a dynamic bias rather than a fixed bias in the "new class a" ploys. Perhaps some are, just as others use a dynamic rail voltage etc. However this is not mentioned in the reference provided, and does not constitute class A in any case, whether "new", or old. Trevor. |
#38
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The simplest amplifier
"Peter Larsen" writes:
Trevor wrote: Right, looks like a straight forward description of class AB. Obviously NOT class A. My understanding is that they are using a dynamic bias rather than a fixed bias in the "new class a" ploys. Ah yes, jogs the memory. At one time, dynamic bias was quite the thing in some circles, IIRC. Have no idea how well it worked, though. I think the concept probably fell out of favor because it was way more trouble than simple fixed-bias AB. And to the OP: @ 40 wpc, if truly class-A, the thing would be massively heat-sinked, uncomfortably hot to touch all the time it was on, weight a ton, and you could easily heat the room (a couple of rooms?) with it. If you want to swap it out for something more compact, seems like some good suggestions have been made. But who knows -- you might have a sleeper. Try "Audiogon" or one of those audio gear sales sites. They might laugh, or you might find some devotees who really like that model, and its sale would cover your replacement. Good luck with it, Frank Mobile Audio -- |
#39
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The simplest amplifier
Scott Dorsey wrote:
Frank Stearns wrote: At one time, dynamic bias was quite the thing in some circles, IIRC. Have no idea how well it worked, though. It worked okay. It gave low distortion at low levels, and as you got to higher levels the crossover distortion increased substantially but since it made less of a contribution to the total signal it wasn't a big deal. I'm using a pair of "new class a + dc servo" Sansui B55's to power compression drivers, one of those with so much input attenuation that 1 volt in produces 0.6 volts out. They were good out of the shrink wrap and once the input coupling cap was replaced with polypropylene and the octave band analyzer display card was removed they got extemely transparent. I think the concept probably fell out of favor because it was way more trouble than simple fixed-bias AB. I think it mostly fell out of favor because the numbers on the marketing handouts didn't look as good as a fixed-bias amplifier. You measure the distortion at full power, where it's highest. And higher component count and manufacturing complexity and the overall loss of clarity in early digital stopping the quality wars. Digital was perfect so there was nothing more to improve, remember? Kind regards Peter Larsen |
#40
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The simplest amplifier
Frank Stearns wrote:
At one time, dynamic bias was quite the thing in some circles, IIRC. Have no idea how well it worked, though. It worked okay. It gave low distortion at low levels, and as you got to higher levels the crossover distortion increased substantially but since it made less of a contribution to the total signal it wasn't a big deal. I think the concept probably fell out of favor because it was way more trouble than simple fixed-bias AB. I think it mostly fell out of favor because the numbers on the marketing handouts didn't look as good as a fixed-bias amplifier. You measure the distortion at full power, where it's highest. And to the OP: @ 40 wpc, if truly class-A, the thing would be massively heat-sinked, uncomfortably hot to touch all the time it was on, weight a ton, and you could easily heat the room (a couple of rooms?) with it. Pioneer did actually made a class A receiver back in the seventies. It did indeed weigh a ton and you could heat a room with it. If you want to swap it out for something more compact, seems like some good suggestions have been made. But who knows -- you might have a sleeper. Try "Audiogon" or one of those audio gear sales sites. They might laugh, or you might find some devotees who really like that model, and its sale would cover your replacement. It is a weird world. There is someone out there who will pay a premium for anything you have, the problem is finding them. --scott -- "C'est un Nagra. C'est suisse, et tres, tres precis." |
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