many many pics here
taken with a few types of cams that i can borrow, so excuse me for some low quality pics. u may hotlink the pictures here if u want
taken with a few types of cams that i can borrow, so excuse me for some low quality pics. u may hotlink the pictures here if u want
I'm the builder of the GC3 that quekky posted.
Just a little correction to the info on his site: the main caps are rubycon ZL 1000uf/50v, mot panasonic FCs, and the single cap on the chip is a panasonic NHG 470uf/100v.
The rationale for building it this way is to reduce the amount of wiring from the diode board to the amp, while maintaing the advantage of having caps mounted close to the chip. The single cap also reduces problems with grounding, and makes the amp very compact.
It might not be much ground gained when there's only 1 pair of GCs, but I'll be building a 6 channel amp in that chassis...
About the sound:
The evaluation of the 3 GCs are done on the following system:
Pioneer dvd-233 as transport
DIY PCM1704 dac (elektor DAC2000)
DIY Preamp (opa627 based)
DIY speakers (Scanspeak 18w8546 + D2905/9700)
All cables are belden 89259, speaker cables are cross coupled 89259s as well.
GC1 is the most well balanced among the 3, and the one that has been run in for the longest period (a couple of months). This was the only AC coupled GC in the test, and uses a 100/6.3 BG Hi-Q NX (?) at the input.
The BG cap was very good! but we felt it softens the details somewhat. Other than that it was remarkably transparent, and didn't really change the balance too much. Strange, I heard polycaps done much worse than this electrolytic...
Quekky's GC2 was the only conventional GC in the test, and it showed some rather suprising properties even with very inexpensive parts. The caps are nippon chemicon KMEs and the resistors are generic metal films. The sound was bright, open and very airy. Too bright and airy, infact, and we thought it sounded a tad unnatural. We thought it could be due to the resistors, since the other 2 GCs that used Dale Rn60d resistors sounded 'mellower' and perhaps more natural. The difference is rather like those between dynaudio d260s and scanspeak 9300/9500s. I prefer the SS
Lower mids and down, it wasn't a great deal of difference between the GC1 and GC2.
My GC3 sounds very similiar to the GC1 (same resistors) from upper bass and up, especially after we have bypassed (shorted) the BGs on the GC1. The bass was rather woolier than the other 2, but it was probably due to the fact that the GC3 was brought into the test directly from the workbench. As the listening tests went on, its seems that the character of the bass is slowly changing, and becomes much closer to the other 2 at the end.
Verdict:
The resistors are very important! I think the effects are large enough for the choices to play the part of a "tone control", adjusted to harmonise with the rest of the system. I would try rikenohms next time round.
The GC2 have, despite the brightness "problem", a certain je nais sais quoi to its sound, that the other 2 didn't really have. There are too many variables involved to say where exactly this magic lies, but I would guess that its in the power supply.
Next, the power supply voltages used are +/- 26v DC in all instances, and it was enough for normal listening levels. It is, however, not quite sufficient for those times when we really want to crank it up. The dynamics (particularly bass) of all the amps are rather subdued too.
Now, it would be really cool to have a SS 50-80w class AB amp of simliar sound quality to the GCs, but with better bass and dynamics...
Just a little correction to the info on his site: the main caps are rubycon ZL 1000uf/50v, mot panasonic FCs, and the single cap on the chip is a panasonic NHG 470uf/100v.
The rationale for building it this way is to reduce the amount of wiring from the diode board to the amp, while maintaing the advantage of having caps mounted close to the chip. The single cap also reduces problems with grounding, and makes the amp very compact.
It might not be much ground gained when there's only 1 pair of GCs, but I'll be building a 6 channel amp in that chassis...
About the sound:
The evaluation of the 3 GCs are done on the following system:
Pioneer dvd-233 as transport
DIY PCM1704 dac (elektor DAC2000)
DIY Preamp (opa627 based)
DIY speakers (Scanspeak 18w8546 + D2905/9700)
All cables are belden 89259, speaker cables are cross coupled 89259s as well.
GC1 is the most well balanced among the 3, and the one that has been run in for the longest period (a couple of months). This was the only AC coupled GC in the test, and uses a 100/6.3 BG Hi-Q NX (?) at the input.
The BG cap was very good! but we felt it softens the details somewhat. Other than that it was remarkably transparent, and didn't really change the balance too much. Strange, I heard polycaps done much worse than this electrolytic...
Quekky's GC2 was the only conventional GC in the test, and it showed some rather suprising properties even with very inexpensive parts. The caps are nippon chemicon KMEs and the resistors are generic metal films. The sound was bright, open and very airy. Too bright and airy, infact, and we thought it sounded a tad unnatural. We thought it could be due to the resistors, since the other 2 GCs that used Dale Rn60d resistors sounded 'mellower' and perhaps more natural. The difference is rather like those between dynaudio d260s and scanspeak 9300/9500s. I prefer the SS
Lower mids and down, it wasn't a great deal of difference between the GC1 and GC2.
My GC3 sounds very similiar to the GC1 (same resistors) from upper bass and up, especially after we have bypassed (shorted) the BGs on the GC1. The bass was rather woolier than the other 2, but it was probably due to the fact that the GC3 was brought into the test directly from the workbench. As the listening tests went on, its seems that the character of the bass is slowly changing, and becomes much closer to the other 2 at the end.
Verdict:
The resistors are very important! I think the effects are large enough for the choices to play the part of a "tone control", adjusted to harmonise with the rest of the system. I would try rikenohms next time round.
The GC2 have, despite the brightness "problem", a certain je nais sais quoi to its sound, that the other 2 didn't really have. There are too many variables involved to say where exactly this magic lies, but I would guess that its in the power supply.
Next, the power supply voltages used are +/- 26v DC in all instances, and it was enough for normal listening levels. It is, however, not quite sufficient for those times when we really want to crank it up. The dynamics (particularly bass) of all the amps are rather subdued too.
Now, it would be really cool to have a SS 50-80w class AB amp of simliar sound quality to the GCs, but with better bass and dynamics...
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