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Old 30th April 2004, 11:19 PM   #21
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Quote: "I am using 10,000uF caps for both rails"

Most people suggest that a GC PS cap with higher than 1000uF ruins the bass.

This happens to both LM38XX and LM4780.

Swap it with a good 1,000uF cap, not 10,000uF!
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Old 1st May 2004, 07:20 AM   #22
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teoh,
first of all, check that your preamp is working fine by using a commercial power amp or something. you can benchmark your creation to a commercial amp too later on.
if your gainclone is 'ringing', most probably there is something wrong with your layout which causes oscilating, etc.. under a normal condition, you dont even need the zobel network. if you can take a photo for us to see, that would be a great help.

oh, another thing, dont expect the 3875 to give you the techno thump-thump-thump!!! my sony has much louder 'thump!' compared to my gainclone, but later on i discovered that this is because the sony was designed not to have a flat frequency response. in another words, it was designed for teenagers who cant live without loud bass in their music=) good for business.

cheers
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Old 5th May 2004, 01:38 AM   #23
cwteoh is offline cwteoh  Malaysia
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Quote:
Originally posted by jamesjung21

Most people suggest that a GC PS cap with higher than 1000uF ruins the bass.

This happens to both LM38XX and LM4780.

Swap it with a good 1,000uF cap, not 10,000uF!
Hi James,

Initially, I started with Panasonic FC Caps 1000uF but it did not help too.

Quote:
Originally posted by skyraider
teoh,
first of all, check that your preamp is working fine by using a commercial power amp or something. you can benchmark your creation to a commercial amp too later on.
if your gainclone is 'ringing', most probably there is something wrong with your layout which causes oscilating, etc.. under a normal condition, you dont even need the zobel network. if you can take a photo for us to see, that would be a great help.

oh, another thing, dont expect the 3875 to give you the techno thump-thump-thump!!! my sony has much louder 'thump!' compared to my gainclone, but later on i discovered that this is because the sony was designed not to have a flat frequency response. in another words, it was designed for teenagers who cant live without loud bass in their music=) good for business.

cheers
Hi skyraider,

Regarding the "ringing", it was a secondary waveform evolved form the main waveform (on right hand side of positive peak when tested with sinewave signal). This happened when connected to fullrange speaker and it becomes worst when connected to two way speaker with crossover. The "ring" disappeared when I installed the zobel network. According the the informatin i got from the net, this "ring" was caused by the inductance effect on the speaker system. I will post a picture of it when I have accessed to a digital camera.

Thanks.
__________________
Regards,
C.W. Teoh
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Old 5th May 2004, 02:43 PM   #24
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Quote:
Originally posted by jamesjung21
Quote: "I am using 10,000uF caps for both rails"

Most people suggest that a GC PS cap with higher than 1000uF ruins the bass.

This happens to both LM38XX and LM4780.

Swap it with a good 1,000uF cap, not 10,000uF!
If this is the observation, what is the theory behind this.? It would seem that larger capacitors would give a better temporary reserve of power for demanding bass requirements. Why would higher capacitance cause "less bass"?

Sorry if this has been covered before. A pointer to a tread would be helpful.
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Old 5th May 2004, 03:28 PM   #25
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Do a search on "placebo effect" or "power of suggestion" and it will become obvious to you. I realize that the undersized capacitor and extremely small feedback has gained a cult following (and I would imagine I will be flamed for this post), but as far as effect on sound goes, it belongs with the silver wire and $50 capacitors.

btw, yes I have built a few gainclones and was not impressed by any changes in feedback length, or reducing power supply capacitance.
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Old 7th May 2004, 12:15 AM   #26
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Ray,
I have never tried the silver wires and exotic caps... what is your opinion on them?
I am currently using kenwood audio grade caps, and they works fine for me, but theres no harm in experimenting-)

Thanks
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Old 7th May 2004, 07:31 AM   #27
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Quote: "I am currently using kenwood audio grade caps, and they works fine for me"

Kenwood caps? Interesting...

Where could I get one from?
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Old 7th May 2004, 10:24 AM   #28
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Quote:
Originally posted by cwteoh
1) I am using 10,000uF caps for both rails but do not have the 100uF and 0.1uF caps at chip.
No caps near the chip?
That's your problem, and you started fiddling with big caps on the PSU and with the feedback loop.
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Old 7th May 2004, 03:37 PM   #29
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skyraider - my opinion on exotic caps and silver wire is the same as my opinion on highly overpriced "Monster" cable and the like. If you think they look cool, then by all means its your amp, do what you like, but don't decieve yourself into thinking they sound better than your regular garden variety components. Its like anything else in life... if you have 50 bux to throw away on a couple capacitors rather than a whole handfull of parts for new amplifiers, then go ahead and throw

Remember, if you can't consistently differentiate between components / amplifiers in a true blind A/B test, then you can be sure the difference is really in your mind, not in the components.
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Old 8th May 2004, 01:19 AM   #30
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James,
i bought the caps from local stores in malaysia, they look serious and proper in metal housing like the panasonic types, so i am sold for that-) It says "for audio" on the jacket too, but i never got around to search more about it..


Ray,
I have the same opinion on the exotics too. For me, everytime i changed some cheapo parts on my amp, there are differences in the sound. However, to a certain level, I dont notice any differences. I think some people wants to have that extra 2-3% and dont mind spending the bux on that even though they dont really hear the differences. To a certain level of hi-fi, the effects of exotics would not be noticed.But its comforting to know that they have the best in their system, and psychologically, it sounds 'better'. -)
Anyway, if i can get my hands on some BGs, its worth a test.
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