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Chip Amps Amplifiers based on integrated circuits

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Old 14th March 2003, 02:41 AM   #1211
Fred Dieckmann is offline Fred Dieckmann  United States
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Wink I'm not sure if active PS will sound good

And you never will making idle speculation without trying it. The soft recovery diode stuff is very old news. I don't think anybody has even mentioned the really good diodes to use or experimented with snubber circuits or RC filters for the supply. It is very interesting that everyone is only concerned about bass response and ripple with 1000uf caps. I would be more concerned about a 1000uF cap being an adequate high frequency decoupling cap. Also Black Gate caps often don't work well in parallel with other caps. I guess everybody has all this stuff figured out already....... I think I will keep experimenting though.
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Old 14th March 2003, 02:53 AM   #1212
nania is offline nania
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Fred

do you mean to say that IF and or RF will be introduced by the 1000 uF value or that the 1000 uF value will fail to attenuate the higher frequencies. Also, is there anything unique about the BG caps that makes this more of an issue with other caps? Oh and since you brought it up, which do you think would be the best type of diode/bridge to rectify the PS?
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Old 14th March 2003, 03:27 AM   #1213
Peter Daniel is offline Peter Daniel  Canada
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Default Re: I'm not sure if active PS will sound good

Quote:
Originally posted by Fred Dieckmann
And you never will making idle speculation without trying it. The soft recovery diode stuff is very old news. I don't think anybody has even mentioned the really good diodes to use or experimented with snubber circuits or RC filters for the supply..
From what I remember, at least pinkmouse was experimenting with snubbers and he didn't like it. I tried a filter on AC line and didn't like it either. I even added additional 1000u BG at the bridge and it sounded worse. I used AC conditioner with the amp and it also made things worse. This amp seems to be in favour of making things simple.

One other thing I found out, is that when you parallel two fuses it improves the sonics a lot.
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Old 14th March 2003, 03:34 AM   #1214
Fred Dieckmann is offline Fred Dieckmann  United States
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1000 uF value will fail to attenuate the higher frequencies
and possibly contribute to amplifier instability depending on the exact capacitor type. The National Semi app notes show 0.1 and 100uF local decoupling for the LM1875. I once built an audio circuit that sounded much diiferent with caps of the same brand, value, and series but had different form factors. One cap type was taller and smaller in diameter than the other type. The caps were both Panasonic HFQ types.


"Is there anything unique about the BG caps that makes this more of an issue with other caps?"

Yes and there are some other caps as well that could have problems. Putting a film cap in parallel with a Black Gate was described to me by one designer as "The Kiss of Death" for sonics. I have had the experience certain electrolytics sounding bad with Black Gates and paralleled Black Gates sounding fine. This is not a given and your milage may vary. I have often heard 0.01 film caps screw up the sound on supply bypassing. It pays to do substantial experimentation on capacitor bypassing especially with the Black Gates.
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Old 14th March 2003, 03:47 AM   #1215
Fred Dieckmann is offline Fred Dieckmann  United States
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Unhappy This amp seems to be in favour of making things simple.

I like snubbers on some high speed soft recovery diodes. ALL amplifiers are sensistive to all this stuff. Most line filters sound bad. Putting 0.1 or 0.22uf metalized film caps across fuse holders often helps the sonics. Jeff Rowland was doing this 10 years ago as well as capacitor coupling the AC input to the power transformer.

Like I said...... you guys think you have all this stuff figured out.
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Old 14th March 2003, 04:27 AM   #1216
45guy is offline 45guy  United States
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Fred,

I hope you have not taken my questions the wrong way. I certainly don't think I have it all figured out. I feel that if you ever stop learning, you might as well just roll over and die. I also try not to take the viewpoint that there is only one way to accomplish the same goal, especially if the end result is something that can be judged subjectively.

I am actually interested in what you came up with and if anyone else has employed something similar. Voltage regulation is rarely seen in tube designs, hence my questions. I know I'll be looking through my parts bins for some LT108x tomorrow. There's more than one way to skin a cat!

I have not noticed the lack of bass that many claim, especially when using the LM1875. I also did not find my version to be too hard sounding at all, unless pushed to volumes that are too loud for my ears. I would say that it is full and tube-like without getting at all flabby in the low end, like so many of my tube experiments. That being the case, I still can't explain why it can sound the way it does with so little capacitance to draw from. Part of the mystery of this chip, I guess.

I know Peter has tried MANY variations and has stated that if he took the time to audition every possible combination of topologies and parts, his product would never make it to market. Time is my worst enemy too...anyone with kids knows what I mean.

Keep up the good work,
Tom
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Old 14th March 2003, 04:28 AM   #1217
jh6you is offline jh6you
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Default Re: This amp seems to be in favour of making things simple.

Quote:
Originally posted by Fred Dieckmann

capacitor coupling the AC input to the power transformer.

Could you give me a brief explanation? What is the reason that the rated voltages of the capacitors (back-to-back) are not a matter in this application?

JH
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Old 14th March 2003, 04:28 AM   #1218
Philo is offline Philo  United States
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Fred,
We know we are not trying to reinvent the wheel, just trying to see for ourselves how different types of wheels ride on the wagon. Nobody said anything about having it all figured out. As you were expressing before concerning BG caps, its the combination of parts that can make the difference. Are you trying to move this thread in a different direction? If you have an idea, out with it, Man. You seem to favor a regulated supply. What are these really good diodes. Are they something we should try? Give up the goods!
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Old 14th March 2003, 04:42 AM   #1219
Peter Daniel is offline Peter Daniel  Canada
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Default Re: This amp seems to be in favour of making things simple.

Quote:
Originally posted by Fred Dieckmann


Like I said...... you guys think you have all this stuff figured out.
I didn't say that and I don't think anybody will ever have it figured out completely. New discoveries happening every day.

BTW, I don't even have it figured out, what I'll be doing tomorrow.
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Old 14th March 2003, 07:45 AM   #1220
Nuuk is offline Nuuk  United Kingdom
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Quote:
One other thing I found out, is that when you parallel two fuses it improves the sonics a lot.
You may then find that a circuit breaker is even better! I don't have fuses in any of my equipment.
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