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Old 11th June 2007, 01:49 AM   #11
Arx is offline Arx  Canada
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Yes, I believe you are right regarding the capacitance on internal cables. In my chipamps, I've instead minimized the length to be insignificant. (input connector is right beside the amp chip), so I can't say how much difference it makes. I think not much.

As far as high frequency rolloff is concerned, it's not going to make a difference whether you use a pot or a stepped attenuator.

If you have a problem with high frequency rolloff, the only ways to fix it is to either increase the input impedance of the amp (making it more sensitive to noise) or reduce the loading on the input by buffering with an active preamp, which doesn't necessarily need to be complicated.

Whether this will be a problem or not depends on your source.

Try it and see.

That said, if you want very good channel balance, the stepped attenuator might be nice.

-Nick
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Old 13th June 2007, 01:33 AM   #12
Leolabs is offline Leolabs  Malaysia
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Do add some regulators consider an upgrade too???
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Old 13th June 2007, 02:30 AM   #13
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Quote:
Originally posted by Nuuk
IMHO, and after trying most things, a simple GC is still the best GC!

Don't bother with BGs in a GC. Panasonic FCs and MUR 860's work well in a GC (although not necessarily elsewhere)

Solid core wiring for signal is fine (you don't need silver etc for those short lengths). Just keep it short and tidy.

Dual mono PSU is best with 37 volt rails (if you have 6-8 ohm speakers).

I prefer the PSU in a separate enclosure. I also prefer a non metallic enclosure for the amp.

Resistors - won't cost much so try what you fancy.

Zobel - won't cost much so try with and without.

:attn: One of the biggest improvments I got with GCing was to build a four channel amp and bi-amp the speakers.

Finally, remember that a lot depends on what goes before the GC! ie you may need an active pre or buffer stage.
That's right on, a simple GC is still the best GC and I was promoting it for last three years without basically changing anything in my initial circuit.

Regulated supplies, batteries, switching supplies, snubbers, Zobels, big caps, all came and are gone now (at least for me), and simple GC still rules.;-)

Panasonic FC caps are indeed the best value for the money and it's hard to improve on them.

The biggest change, in my system, came with using small BG N caps directly at the chip and larger BG STD at the rectifiers. That changed the sound in a right direction and for me there was no way back. Although some of my friends still prefer large BG STD at the amp.

The 10uF caps that come with a kit are not neccessary to be used, depending on a setup, the amp may actually sound better without them, so try both ways. I noticed that placing only one cap in negative supply may be better than using both of them (but that was mainly with BG N caps)

I would not go with standard resistors any longer though, as more"exotic" types offer more flavour and definition, but you need a right system to notice that. However, you may save by skipping input series resistor (220R in my kit) as that resistor is not really needed for the amp to function properly. Riken can be replaced by Kiwame, although there is slight difference in their signatures: Kiwame is more sweet and lacks the "bite" which I find quite desirable with Rikens (Rikens are out of production now, and if they are gone I will start using Kiwames). Input shunt 22k is equally important as 22k feedback resistor and Caddock MK132 is still best for me here.

Transformer is probably responsible for some 20% of good sound and if you use really cheap stuff the bass and PRAT may suffer. I find Plitrons quite good and only custom made toroids with amorphous cores were better, but I can't source them any longer.

PS wire makes probably 8% of the sound, for me Cardas is best suitable here, however much cheaper DH Labs hook up wire wasn't bad either and the difference was like comparing Rikens and Kiwames (too sweet for my taste).

Input signal wire is more critical than output wire, but I would not go with anything special here. Solid core silver from DH Labs is good, as well as gold plate copper I use most frequently now for signal. Just try to keep all connections short and you may be able to go away with most everything. For output, I use either Kimber or DH Labs (19ga). Altough one person I know about found GC addictive only after replacing signal wire with solid core silver. Cardas silver wire offered by Percy is pretty cheap and quite good.

Now, it may sound surprising to some, but chassis is actually pretty important and depending how you build it the sound may vary quite substantially. I can't offer any receipe here and I usually approach it with an open mind attitude, where everything can matter. My best creation so far was described here: The most advanced GainClone amp yet

Please note, that if you have balanced source, the bridged GC will be better than regular one, especially when it comes to dynamics and bottom end extention. But you need the speakers that are at least 6ohm.

The bi-amping is also a big advantage, and the GC will sound only as good as the rest of your system, if it sounds bad, the fault is usually somwhere else ;-)

Attached is schemnatic of my Patek amp.
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File Type: jpg gc new.jpg (18.4 KB, 4976 views)
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Old 13th June 2007, 03:04 AM   #14
BWRX is offline BWRX  United States
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Most effective upgrades:

- Stiff power supply (consider regulated supplies if using lower rail voltages and/or higher impedance speakers)
- Low impedance drive for the inputs
- Balanced or differential operation
- Adequate heat sink
- Replace gainclone with class d amp*


*
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Old 13th June 2007, 03:10 AM   #15
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Quote:
Originally posted by BWRX

- Replace gainclone with class d amp*

*
Forget Class D amp. If you really want to upgrade from GC, use properly built Zv9 with tweeter crossover cap connected directly to the amp's output (bypassing the usual high value electrolytic).
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Old 13th June 2007, 03:15 AM   #16
BWRX is offline BWRX  United States
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Quote:
Originally posted by Peter Daniel
Forget Class D amp.
I would but I really like how some of them sound in my system The higher efficiency is a nice benefit too.
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Old 13th June 2007, 03:22 AM   #17
ttan98 is offline ttan98  Australia
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Peter,

Your input is timely, thanks...
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Old 13th June 2007, 08:13 PM   #18
Arx is offline Arx  Canada
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Yes, chassis is important. My amplifier sounded 6.454% better after I brushed the aluminum.
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Old 13th June 2007, 08:58 PM   #19
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Hi uncle leon re: your question in Post #10 about the editing function. I think it is to stop people adjusting previous posts when they get into contenious debates. This current thread is very civilised but some are fairly intense debates and go on for months or years with a lot of "quoting" from the various participants. If the edit function had no time limit then the less scrupulous antagonists may be tempted to go back and "re write history" and "ammend the records" etc with all sorts of helpful/funny/scandalous results. Or simply they may just like to be able to change a previous faux pas so as to not look like a complete goose! I may be wrong but I think this is the reason. Seems reasonable to me.
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Old 13th June 2007, 10:14 PM   #20
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Correct in just about every aspect Jonathan.
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