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#81
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Clean Power?
Mark, why not glue a pair of 4 channel Jensens together and slap an external
pyramid crossover on them, it would of saved you a ton of cash. My opinion is that there is nothing better then eating steak and drinking a beer while trying to convince others that dog food and tonic water tastes just as good. What kind of amps do you have? I'll bet you don't run Dual/Jensen/Pyramid amps do you? I run a/d/s/ and ESX right now because I know of no other 8 channel amps with crossovers as extensive as these and a reliatively inexpensive price tag. |
#82
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Clean Power?
Why am I posting this to JD you ask. It is because he has a lot to offer
this group and when he gets sniped at, his response is always civil. We can learn much if we do as he does. Unless he's arguing with Eddie Runner, in which case who can blame him for getting nasty? |
#83
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Clean Power?
Mark, why not glue a pair of 4 channel Jensens together and slap an external
pyramid crossover on them, it would of saved you a ton of cash. You dont even read the threads do you? Your arguing a point that noone else is. There are tons of reasons to buy another amp and the LEAST of which is Sound quality, because if you operate it within its linear range your fine. My opinion is that there is nothing better then eating steak and drinking a beer while trying to convince others that dog food and tonic water tastes just as good. Well my opinion is there is nothing better than eating good steak and the finest beer while your eating the leftovers and a dollar draft while trying to convince me I have dog food. Howdy quote me and tell me where I am wrong on this issue. Just do it, if I am so wrong as you say then just quote me and provide evidence to the contrary. Les |
#84
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Clean Power?
Mark, why not glue a pair of 4 channel Jensens together and slap an
external pyramid crossover on them, it would of saved you a ton of cash. Why would I want to do that? That's awfully messy. Can you seriously provide another alternative? I don't know of any other unit that would have done what I wanted for a lower price. By the way, what's wrong with Jensen amplifiers? Carsound.com seemed rather impressed with them. Their distortion content was lower than the Zapco they tested (not that it matters anyway, because humans can't tell the difference between 0.05% and 0.2% THD anyway). |
#85
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Clean Power?
Mark, you forgot two of the biggest reasons of all: Peer Pressure and
Status. Who's going to buy something when they know their friends or anyone that looks at it will laugh or call them a newbie or cheap, or a punk-ass bass kiddie that likes distortion more than music? The people that usually do end up buying the cheaper amps usually either can't afford anything better, just don't give a crap and want just a little bit more bass, or actually realize when something will work for them and are price-aware. Brandonb Mark Zarella wrote: I should add, by the way, that there are additional reasons for buying better built amplifiers. But none that I can think of that directly relate to "clean" vs. "dirty" power. For instance, when you're driving low impedance loads, some amps crap out sooner than others. When you're driving an amp to its limits, some overheat and shut down. "Better" amps often don't. But I think you'd be quite surprised to find that there are some pricier amplifiers that are less stable under these circumstances than others. For example, I've had a tougher time with Profile amps overheating than Jensens, yet the general concensus among car audio groups is that Profile amps are supposedly "mid grade" whereas Jensens are "junk". I'd actually put some of the newer Jensen amps up against Kenwood, Profile, Sony, Audiobahn, Alpine, etc in terms of reliability. |
#86
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Clean Power?
Honestly, I don't know. ESX amps are fairly cheap for what they deliver. I
have never used one myself, but Robert Zed's gear has never disappointed me yet, I've always liked his early HiFonics gear. Why would I want to do that? That's awfully messy. Can you seriously provide another alternative? I don't know of any other unit that would have done what I wanted for a lower price. Well maybe when used on tweeters or mids there is nothing wrong with Jensen, but powering subwoofers they sound crappy and if you get silly enough to run one at two ohms, you might get 30 minutes out of it, if lucky before it goes thermo. It seems that you are looking at the amp's specs and over looking the real test. Fire up a Jensen and check it out for yourself compared to say your ESX. If you still disagree, I'll trade you my Jensen for your ESX and I'll even go as far as throwing in a free profile amp for wasting your time. By the way, what's wrong with Jensen amplifiers? Carsound.com seemed rather impressed with them. Their distortion content was lower than the Zapco they tested (not that it matters anyway, because humans can't tell the difference between 0.05% and 0.2% THD anyway). |
#87
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Clean Power?
Lester, I haven't seen you as of yet bring up a point or a belief of any kind
and standing behind it, other then your post regarding Mustangs and where did that get you? The plain truth is that you are nothing but a post sniper and you don't have the balls to question anything that isn't already in argument by others, and even at that your arguments are based on what other's are saying already and never based on thoughts of your own. Your posts are weak as is your spelling. My opinion is that there is nothing better then eating steak and drinking a beer while trying to convince others that dog food and tonic water tastes just as good. Well my opinion is there is nothing better than eating good steak and the finest beer while your eating the leftovers and a dollar draft while trying to convince me I have dog food. Howdy quote me and tell me where I am wrong on this issue. Just do it, if I am so wrong as you say then just quote me and provide evidence to the contrary. Les |
#88
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Clean Power?
Honestly, I don't know. ESX amps are fairly cheap for what they deliver. I
have never used one myself, but Robert Zed's gear has never disappointed me yet, I've always liked his early HiFonics gear. They're well built and versatile. Extensive crossover controls. They easily do their rated output. And I've never had one shut down on me yet. Some in here have not been impressed with their reliability, but I've dealt with almost 10 ESX amps and have never had one fail. Take it for what it's worth. Why would I want to do that? That's awfully messy. Can you seriously provide another alternative? I don't know of any other unit that would have done what I wanted for a lower price. Well maybe when used on tweeters or mids there is nothing wrong with Jensen, but powering subwoofers they sound crappy and if you get silly enough to run one at two ohms, you might get 30 minutes out of it, if lucky before it goes thermo. I agree with that. There has always been issues of them shutting down, much moreso in their amps from the early to mid 90's than in their newer ones though. It seems that you are looking at the amp's specs and over looking the real test. Fire up a Jensen and check it out for yourself compared to say your ESX. If you still disagree, I'll trade you my Jensen for your ESX and I'll even go as far as throwing in a free profile amp for wasting your time. No, the ESX is a better amp for a number of reasons. Flexibility, reliability, crossover controls, power output (I don't know of a Jensen amp that outputs 600 watts into a single channel, despite the ratings). I think you're missing the point of my post. |
#89
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Clean Power?
Huh?
what did I miss? Mark Zarella wrote: Why am I posting this to JD you ask. It is because he has a lot to offer this group and when he gets sniped at, his response is always civil. We can learn much if we do as he does. Unless he's arguing with Eddie Runner, in which case who can blame him for getting nasty? |
#90
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Clean Power?
From a repairman's standpoint they may not be exactly the same but they're
damn similar. ferinstance-take a great american amp-the series VIII Hifonics Zeus. Power supply fets are IRFZ44N, has the same type transformer almost everybody uses, and uses a TL494C PWM control IC for the regulated power supply. The cheap ol Lanzar Vibe 250 uses the SAME components, down to the exact same number of drivers, but has lower quality solder and a lower quality PCB. The Vibe has a lower rail voltage, so produces 50 less watts per channel than the hifonics, but it did bench test a good 250W per channel into a 4 ohm load. It doesn't clip as gracefully as the Hifonics, but it does use the SAME PARTS in the power supply. 90% of amps made use a TL494 regulator and the same power supply topology, with some minor differences just so they can market it as being different. As to all amps sounding the same WHEN OPERATED WITHIN THEIR DESIGN LIMITS, I agree. I've been in the audio business for 14 Yrs both as a repairman and an installer and I've seen cheap outdo expensive and the other way around. A lot is in how the operator uses it, and the quality of the install. -- Jammy Harbin J & J Electronics, Inc 227 S. 4Th St. Selmer, TN 38375 731-645-3311 "Pug Fugley" wrote in message hlink.net... That's mainly a product of the power supply. But Zarella seems to think that ALL amps have the same exact power supplies in them for some reason. "Captain Howdy" wrote in message ... I don't understand how this could be a wattage issue, since this is an auditable difference at low volume levels. A few years ago I was running a 1200 watt 4 channel Pyramid bridged in to a pair of 4ohm 12's and it powered them nice and loud, but there just wasn't any low bass at low volume levels. Then I replaced it with a Kicker IX704 amp which had loads of grindage at low volume levels. But oddly enough it did not hit as hard at high volume levels. It's not just the Pyramid, I have a pair of Profile amps here that act the same way. In article , "Mark Zarella" wrote: What I have found with so called cheap amps such as Profile, Jensen and Pyramid is that you have to crank the hell out of them to get deep bass. Where more costly amps such as Orion, Kicker, PPI and MTX seem to produce deeper bass at lower volume levels. I also found that these cheaper amps seem to run a lot hotter. The only reason for this that I can think of is an inadequate power supply. No, that's not a problem. Every "cheap" amp I've ever tested has a flat frequency response down to 20 Hz (lower in fact). This is well documented actually. What you're undoubtedly experiencing is a lack of power. Use a bigger "cheap" amp and you won't run into this. |
#91
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Clean Power?
Correct on the 4 ohm power, they are speced as though they double power
@ 2 ohm but in reality the 4 ohm power is just higher than speced and the amp shows a typical increase of 50-60% from 4 ohm to 2 ohm. I'm not sure how many versions of the original P450/650/850 there are, but your assessment of them sounds pretty accurate. The ".2" version has two versions, the first-gen was being produced in Phoenix and we then debugged it before moving to turnkey production at the same factory that had produced the PCB's all along. The ".2" models are pretty much bulletproof and work flawlessly, provided you're willing to spend a couple of hours getting acquainted with the front end features so the installed product is configured optimally. It's easy to get in a hurry and screw up the signal routing or make conflicting crossover settings. I guess that's the penalty for having as much control and versatility as these do - it does require a more competent installer to get the best out of the installed product. Which isn't all bad... JD John Andreen wrote: A/D/S did make some higher powered amplifiers prior to my working there. I believe that they were 2 x 100, but I can't be certain. During my tenure, the most powerful amplifiers were the ADS P450, P650 and the P850. They actually made closer to 75 watts per channel. These amplfiers are really PPI Powerclass outputs with the crossover sections being true ADS. The input sections were my design. Not really, because I simply got my inspiration from another design that I found on the web. I did change it though to suit our requirements. I can also tell you that there are two distinct versions of these units. Maybe three now, the third being DEI's version. Without actually looking at the PCB's there is no real way of telling if it is the earlier version ( pure A/D/S ) but has issues, mostly turn on pop and the later versions ( A/D/S / PPI ) which are really stellar performers. The digital displays of the PH30 and PQ40 are actually quite worthless as it doesn't really display the frequency, but a frequency found in a lookup table relative to the position of a potentiometer ganged with the frequency pot. This is only an approxomation at best, and there is inherent slop and backlash associated with potentiometers. I also had to modify the software coding ( Many thanks to Campbell Kelly for his help ) to stop the display from drifting or blinking. I seem to recall 5 distinct amplifiers in the A/D/S line during my tenure. the P450, the P650 and the P850 and the two models with the digital displays. These other two units were the PQ40 and the PH30. These are the units that make 4 x 100 (PQ40) and 6 x 75 (PH30). Really great amplifiers, but never trust the frequency displays. BTW the LED displays were supposed to be blue, but we had a butt load of RED LED displays leftover from an older version. All the .2 versions of these 5 amplifiers have the true balanced differential input section that I had a hand in. Makes for a much quieter amplifier. JA Mark Zarella wrote: I can also tell you that A/D/S pretty much made extremely good units except for a few choice "dogs". I can only currently think of only one. I can't remember the model, but it had several DSP processors on board. Also had 5, yea 5 separate power supplies. Each one "yanking" the amplifiers ground all over creation. They also had a rather good Audio Engineer's ( Ed Meitner ) pre-driver stage that was particularly good at rejecting Power supply noise or any "common-mode" noise for that matter. It was partly their saving grace. I think that your P840 shares this pre-driver technology. If you can get your hands on a schematic of your P840, look for the pre-driver stage. If you see some OPAMPS whose output pins are tied to GND and has JFETS between the +/- 15 volt rails and the OPAMPS input +/- supply pins, then you are indeed fortunate. This type of driver section is usually only used in audiophile grade home amplifiers. Ed performed a miracle and got it to work for a car amplifier. Those amps also typically us Burr-Brown Audio grade OPAMPS as well. I've replaced op amps for people who asked me to before (sometimes along with the discrete components so that I could modify xovers and the like, but that's another story), and never found a noticeable difference afterwards. But admittedly, I never a/b'd them. I wouldn't expect a difference though, since the distortion characteristics of modern op amps tend to be top-notch (and in fact, superior to discrete components as I found out the hard way in one design I was doing for another application). In short, That amp of yours and it's next of kin the P850 are indeed great amps. Just stay away from Constant Bass. This function was implemented incorrectly. If it were done right, it would be a blessing. But, it was implemented wrong and kills your sound stage. Engage this feature and listen to a "sound staging" test CD. You will indeed hear the loss of your soundstage. I'd like to be able to find a higher power 2-channel relative to the P840 for my rear speakers. I currently have a 240 (?) that looks the same, but I was hoping to find something closer to 80x2. Did they make one? |
#92
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Clean Power?
I don't think it's that old, but I could be wrong. Your description
sounds more like a really old P120, which was the larger of the second series (P100 was first, if you don't count the outboard amp for the 2001 biamp speaker system, then the P80 and P120 came out next). The P2110 would have been an early 90's model? Something like that, showed up after the PS5/PQ10/PQ20/PH15 models went through their ".2" phase. JD John Andreen wrote: I was trying to think of that one JD, but I couldn't remember that far back. I seem to recall it being a lighter shade of gray than the new units. I also think that it may have had a self oscillating power supply. I even think I owned one to drive a pair of A/D/S 300i's in a 1977 Datsun King Cab. It got stolen. Replaced it with a Nakamichi P300. It got stolen. I replaced it with a "True" David Hafler MA-1 ( I think that was the model) John Durbin wrote: The P2110 was good for 110wpc... JD |
#93
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Clean Power?
Crack, catch fire, burn large gaping holes around the high-current
components' solder pads - you bet. My point was that the lower reputation implied for build quality for the brand you mentioned belied some good designs they made at one point or another. To be fair, I think you'd have to compare say the PPI 2120/2240/2360/etc. series with the "standard" Sony (current Xplod for instance) and the higher-priced US-designed and built stuff with Sony's flagship pieces. Same argument for Sedona vs. Art series and Alpine Flex vs. V12, Pioneer ODR vs. the "GM" models, Excelon vs. regular Kewood, etc. JD John Andreen wrote: I can't argue that fact as your are correct. I was only trying to make a quick comparison between life spans of products. You and I have been in this vocation a long time and we've had our share of product. I kind of think you had at least one single sided fish paper amplifier board crack somewhere along the way. That was the gist of the point I was trying to make. John Andreen John Durbin wrote: You could say the same about an original Sony XES-M1 or M3... I think you need to establish an apples to apples comparison, can't compare premium product with run of the mill stuff and expect them to "age" the same. JD John Andreen wrote: Mr |
#94
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Clean Power?
negative... I have learned to follow this advice with Ed:
"never argue with a pig, it wastes your time and annoys the pig" Of course, Ed doesn't really get annoyed - he enjoys arguing maybe more than life itself - but it sure does waste some time... JD Mark Zarella wrote: Why am I posting this to JD you ask. It is because he has a lot to offer this group and when he gets sniped at, his response is always civil. We can learn much if we do as he does. Unless he's arguing with Eddie Runner, in which case who can blame him for getting nasty? |
#95
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Clean Power?
Um, that's actually Robert ZEFF, as in founder and chief engineer of
Zapco for many years, and now head of his own consulting firm, Nikola Design... Zed Audio is owned by Steven Mantz, and is the company that built (builds? not sure these days) HiFonics amps and the ESX pieces you mention. The names Zed and Zeff may sound similar but these two guys have VERY different philosophy on amplifiers in my experience... JD Captain Howdy wrote: Honestly, I don't know. ESX amps are fairly cheap for what they deliver. I have never used one myself, but Robert Zed's gear has never disappointed me yet, I've always liked his early HiFonics gear. Why would I want to do that? That's awfully messy. Can you seriously provide another alternative? I don't know of any other unit that would have done what I wanted for a lower price. Well maybe when used on tweeters or mids there is nothing wrong with Jensen, but powering subwoofers they sound crappy and if you get silly enough to run one at two ohms, you might get 30 minutes out of it, if lucky before it goes thermo. It seems that you are looking at the amp's specs and over looking the real test. Fire up a Jensen and check it out for yourself compared to say your ESX. If you still disagree, I'll trade you my Jensen for your ESX and I'll even go as far as throwing in a free profile amp for wasting your time. By the way, what's wrong with Jensen amplifiers? Carsound.com seemed rather impressed with them. Their distortion content was lower than the Zapco they tested (not that it matters anyway, because humans can't tell the difference between 0.05% and 0.2% THD anyway). |
#96
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Clean Power?
Correct on the 4 ohm power, they are speced as though they double power
@ 2 ohm but in reality the 4 ohm power is just higher than speced and the amp shows a typical increase of 50-60% from 4 ohm to 2 ohm. How much higher is "just higher"? I'm not sure how many versions of the original P450/650/850 there are, but your assessment of them sounds pretty accurate. The ".2" version has two versions, the first-gen was being produced in Phoenix and we then debugged it before moving to turnkey production at the same factory that had produced the PCB's all along. The ".2" models are pretty much bulletproof and work flawlessly, provided you're willing to spend a couple of hours getting acquainted with the front end features so the installed product is configured optimally. It's easy to get in a hurry and screw up the signal routing or make conflicting crossover settings. I guess that's the penalty for having as much control and versatility as these do - it does require a more competent installer to get the best out of the installed product. Which isn't all bad... Yeah, I finally found a somewhat competent installer to install my gear, but they royally f'd up the crossover settings on both of my a/d/s/ amps (P840,P240) and my esx amp (which isn't the easiest to configure either). This was even after I brought the amps to them with everything but the gains preconfigured. I had to go to the frikken supermarket parking lot in the middle of the night to mess with everything because i don't trust the scumbags who live around me. :P |
#97
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Clean Power?
not off the top of my head... assuming that not everyone has headed out
to CES, an e-mail to should scare up the answer, probably even a copy of an owner's guide. JD Mark Zarella wrote: The P2110 was good for 110wpc... Do you know if it has a HP/LP or a bandpass xover? |
#98
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Clean Power?
Actual 2 ohm power is usually slightly higher than spec, and 4 ohm power
in an unregulated not-high-current design is usually about 2/3 2 ohm power (that's a very rough approximation). So, if power at 2 ohm is 100WPC, 4 ohm power is probably about 67WPC but the product is only rated for 50WPC, as someone found value at one point in time in setting the spec so the product appears to double power when you halve the load. Throw in a little conservative rating on the 2 ohm number so the 100WPC is actually slightly higher than that, and John's 75 watt figure becomes a very good estimate. JD Mark Zarella wrote: Correct on the 4 ohm power, they are speced as though they double power @ 2 ohm but in reality the 4 ohm power is just higher than speced and the amp shows a typical increase of 50-60% from 4 ohm to 2 ohm. How much higher is "just higher"? I'm not sure how many versions of the original P450/650/850 there are, but your assessment of them sounds pretty accurate. The ".2" version has two versions, the first-gen was being produced in Phoenix and we then debugged it before moving to turnkey production at the same factory that had produced the PCB's all along. The ".2" models are pretty much bulletproof and work flawlessly, provided you're willing to spend a couple of hours getting acquainted with the front end features so the installed product is configured optimally. It's easy to get in a hurry and screw up the signal routing or make conflicting crossover settings. I guess that's the penalty for having as much control and versatility as these do - it does require a more competent installer to get the best out of the installed product. Which isn't all bad... Yeah, I finally found a somewhat competent installer to install my gear, but they royally f'd up the crossover settings on both of my a/d/s/ amps (P840,P240) and my esx amp (which isn't the easiest to configure either). This was even after I brought the amps to them with everything but the gains preconfigured. I had to go to the frikken supermarket parking lot in the middle of the night to mess with everything because i don't trust the scumbags who live around me. :P |
#99
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Clean Power?
Lester, I haven't seen you as of yet bring up a point or a belief of any kind
and standing behind it, other then your post regarding Mustangs and where did that get you? Howdy, do I need to google and show you how dumb you look on every thread? And what are you referring too? I made a point at the beginning and have stuck to it the whole time. What are you confused about Captain Crackhead? Do I need to restate my position? Go back and look at my first post in this thread and its there. The plain truth is that you are nothing but a post sniper and you don't have the balls to question anything that isn't already in argument by others, and even at that your arguments are based on what other's are saying already and never based on thoughts of your own. Your posts are weak as is your spelling. What the hell are you talking about? Because I know basic scientific principles and state those then I am a post sniper? Everything I have talked about is based on physics and the related laws. Not sure how you can restate those over and over again to you and pugsly and make it different. I have had one point to make this whole time, and you and pugsly cant understand it. It started out as clean power and I didnt respond immedietly because what I had to say about "clean power" had already been said. What I would have added would have related to 3phase power and ISO grounds and didnt really want to get in over you guys heads. Which for you there isnt any challenge in that. Now if you have something you want to specifically point out and challenge me on then go right ahead. But you wont cause you have no balls and know your in over your head. Why else would spelling matter? Cause that is all you have. Les |
#100
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Clean Power?
Pug I have been reading through your errr...posts, and I will add my tidbit
weither you want to listen is another thing. This Thought of "Clean power" vs. "Dirty Power" is a rather rediculous concept. What most people mean is Clean power is usally a amplified signal with low distortion and minimal Spurious Harmonics. When any amp is driven within it's limits. The only diffenece in the signal may only be detected with test equipment that will detect differeneces WAY before the Human ear could ever detect a change. This concept of dirty power is usally a Amp driven outside of it's designed capabilities. Where these Capabilities lay are usally where the cost comes into effect. But what several individuals on here are trying to point out, is that if you take a McIntosh amp running 50 Watts without overdriving the amp,, and then Drive the same speaker with say a Boss amp at 50 Watts that isn't over driven. Your gonna be hard pressed to tell the difference. If you think you have the Proverbial "Golden Ear" then just go look up Richard Clark and see about taking his $10,000 amp challenge. The fact is if you beleive that a 1000 Watt $150 amp delivers 1000 Watts RMS, of undistorted power to a speaker, your sorely mistaken. If you do a little research on these cheaper amps, you'll see most of the time that that is a overinflated max power rating. And You'll see that usally they have a msubstatially lower 4 Ohm load wattage. The fact that you can't differentiate Actual Specs. from Factual isn't the fault of other people on this board. And before you start this politcal debate of how much some of the people on this board are idiots. You may want to listen a little longer to where some of these people on here work and do for a living. Trying to play the "know it all" role, just turns people off to listen to what you say or just ignore you. -- 1991 Tornado Red Corrado, CCA Member # 6645 Stereo is a continuous W.I.P. There are two parts to wisdom: 1) Having a lot to say, and 2) Not saying it. "Pug Fugley" wrote in message hlink.net... John Andreen. The only SANE person (besides myself) that I've seen in this newsgroup yet. You guys spouting out advice and acting like you know everything should listen to Mr. Andreen. Trust me, you'll learn something. "John Andreen" wrote in message news:tMXJb.26126$i55.5289@fed1read06... Mr Zarella You are correct, there is always a trade-off between a "clean" amplifier and a "dirty" amplifier. But the "dirty" amplifier will always loose in terms of reliability, distortion, sound quality etc. All at the expense of good Engineering practices and a handful of parts. On a side note, what would you rather be driving, a Yugo or a Mercedes? Ok, not the same, but how about a Yugo or a Ford Focus? But if your life depended on its proper operation all the time, which would you choose? Here is another case in point. Old school PPI amplifiers. Some of these amplifiers are over 15 years old and they are still operating and making great sound. In fact, these units are still highly sought after. Can you say the same for an equally aged Pioneer or Sony? I think you are perhaps using a shifting baseline as to what is "clean" today. Could you also be confusing distortion with noise? They are not the same. You should do some investigation on these subjects. What you say is a measurement of distortion is actually called "THD +N" a.k.a. Total Harmonic Distortion + Noise. Then to make matters worse, some audio companies use filters (read A-weighted) to make there units appear to have low THD+N. To add even more confusion into the mix, this "THD+N" is almost always computationally measured using FFT methods. There are more than a dozen FFT windows ( read measuring envelope ) that can be used to make the measurement. Each will give a return a different value for "THD+N". There is one more thing about measuring "THD+N". One must also specify the power of the signal being measured. One can measure at 1W, 5W, Full rated power, etc. "THD+N" is not constant at all power levels. It is usually higher at very low power levels and very high power levels. At very low power levels, the major component comes from "noise". At very high power levels, the major component comes from "THD". Really "clean" amplifiers have "TH +N" values nearly equal at all power levels under clipping. I can take even the "dirtiest" amplifier and measure extremely low values of distortion. On the order of 1/1000 of a %. That is, if I can choose my own method and power level of distortion measurement. There is also harmonic distortion caused by the sum and difference of two signals. Let's say a 40 kHz square wave from a power supply and a 1 kHz sine wave. There will be strong harmonic distortion at 39 kHz and 41 kHz. There are also artifacts called sub-harmonics of these two signals that will be present. These are the artifacts that can appear down in the audio spectrum. I would also like to point out that music isn't just 1 kHz, but a plethora of frequencies. I have told this group many times not to be concerned with "THD+N" as a figure of merit when buying an amplifier. The human ear doesn't mind even 1-3% THD. It is a "Marketing Tool" designed to sway the masses. Go listen to a high quality pure tube amplifier and a high quality transistorized amplifier of the same output power specifications. Do this test blindly. I am absolutely certain that you will always pick the tube amplifier over the transistorized one as having the better sound. But, that tube amplifier will have distortion figures SEVERAL HUNDRED TIMES WORSE than the transistorized amplifier. Instead, try to buy an amplifier that has Low "TIM" and low S/N. TIM stands for Transient Intermodulation Distortion. Good audio distortion analyzers can find this kind of distortion using the "IMD" settings. Now, onto the subject of noise. Noise is ever present in the audio world. It comes from the amplifiers SMPS. It comes from the Automobiles charging system. It comes from solar wind. It comes from the power transmission lines. In short, it comes from just about everywhere. In my last post, I stated several things that make for a "clean" amplifier. Those things are the items or methodologies used to eliminate or diminish the ingress of noise into an amplifier. I forgot one them. Decoupling capacitors. Once again, do not do any or all of those items, and more effective noise will make it into the audio path. Do all of them right and you will diminish the ingress of noise into the audio path and have a "clean" amplifier. I have measured and tested amplifiers from many of the "top" car audio companies. Some had signal to noise ratios of -50dB, some had signal to noise ratios greater than -100dB. In other words, the best amplifiers S/N was 64 times better than the worst. The reason, one amplifier was more "clean" than anothers. Once again, you can fudge these numbers too. S/N is different depending upon the position of the gain pot. At max gain, S/N to noise will be different than min gain. The difference, a handful of parts and good Engineering practices. QED John Andreen Mark Zarella wrote: There is such a thing as "clean" and "dirty" power. A perfect case in point would be to run your amplifier with a cheap battery charger as its B+ supply. You will hear a tremendous amount of "hum". In other words, it is "dirty" power. At the other extreme, hook up a whole bunch ( maybe 10 ) of automotive batteries in series. Tap the "GND" from the connection between battery 5 and battery 6. Tap the amplifiers output rails (+/-) from the the top and bottom posts. to do this, you must eliminate the SMPS section and some other items. The Rectifying diodes and the bulk rail capacitors to be exact. You now have "clean" Power for your 400W/ch RMS amplifier. Many things can affect just how "clean" an amplfier is. Power supply topology, filter capacitors, Inductors, ferrite beads, transformer type, board layout, star grounding, trace capacitance, trace inductance, PCB layers ( e.g. 1, 2, 4 ). Do all these things right, and you have a "clean" power amplifier. Do any one or all these things wrong and you now have a "dirty" power amplifier. There is even an extreme case where when the output rails do not have enough bulk capacitance, the output feedback circuit goes "open loop" for just a microsecond or so. In this time, the output transistors modulate or "burst" at their peaks causing audible distortion. Lots of cheap amplifiers will do this just before clipping at full power. Not all things are created equal. Power is one of them. If you want a mechanical analog, how about a V-8 piston engine and a jet turbine That's all well and good, but the important thing to examine here is whether the results are significant during normal operation. Hint: by significant, I mean audible. While there are several ways to lower distortion (sometimes at the expense of noise, or at the expense of reliability, or at the expense of other forms of distortion, and so forth), there is of course a threshold at which further reduction is not warranted, nor is it necessarily recommended since there's almost always a tradeoff in some manner or another. So your engine analog holds true, but if your application is to just drive down a road, then either one will perform as well as the other. |
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