I'm almost ready to start building my first GC. I want to build as good an amp as possible to avoid any dissapointment, going to try a circuit posted by Peter Daniels, the actual GainCard circuit.
I was hoping to build the amp into the chassis of an old 1u rack mount amplifier but am concerned about the spacing between components.
There is 1 toroidal (~38V) which I will be keeping for now
Biggest concern is inputs on the back, volumes on the front, approx 14inches across the unit!
Then around 10-12inches to the circuit board area where the heat sinks are, then it would be another 10inches probably required to the speaker terminals. Plus around 6inches of PS leads after the rectifier diodes.
How big an issue is this? what kind of wire/cable should I be using? If I built my own chassis it would have to be from MDF, I would have to buy 2 toroids and build monoblocks, is MDF a good chassis material?
Regards,
Matt
I was hoping to build the amp into the chassis of an old 1u rack mount amplifier but am concerned about the spacing between components.
There is 1 toroidal (~38V) which I will be keeping for now
Biggest concern is inputs on the back, volumes on the front, approx 14inches across the unit!
Then around 10-12inches to the circuit board area where the heat sinks are, then it would be another 10inches probably required to the speaker terminals. Plus around 6inches of PS leads after the rectifier diodes.
How big an issue is this? what kind of wire/cable should I be using? If I built my own chassis it would have to be from MDF, I would have to buy 2 toroids and build monoblocks, is MDF a good chassis material?
Regards,
Matt
As weired as it sounds, it is my impression that chassis affects the sound of a GC amp. How much, it depends on your perception and taste.
Using full size chassis is probably not the best approch (just ask Bricolo
)
One way to avoid long wire runs is to use pot shaft extenders. If you really have to use full size chassis, it may be interesting to use a subchassis (inside a big one) where the main active circuitry is located and somehow separated from the main chassis influence (mostly vibrations). The rest of the space would be devoted to transformers/ rectifiers.
There were comment's on a forum where putting aluminum top cover on the chassis was degrading the performance of otherwise well sounding amp.
As to the wire, you might use solid core copper. It seems like a good choice (0.5mm or so).
Using full size chassis is probably not the best approch (just ask Bricolo
)One way to avoid long wire runs is to use pot shaft extenders. If you really have to use full size chassis, it may be interesting to use a subchassis (inside a big one) where the main active circuitry is located and somehow separated from the main chassis influence (mostly vibrations). The rest of the space would be devoted to transformers/ rectifiers.
There were comment's on a forum where putting aluminum top cover on the chassis was degrading the performance of otherwise well sounding amp.
As to the wire, you might use solid core copper. It seems like a good choice (0.5mm or so).
I would attach heatsink directly to the rear panel (between inputs and outputs) and place the circuitry there too. You might use relays to switch inputs (so wiring is minimised ) and as I mentioned before, add shaft extenders to the pots, so position of potentiometers doesn't affect anything.
Thinking about it more, you actually don't need a heatsink at all. Just use a piece of copper plate (3" x3" per chip) and attach directly to the chassis ( in most convenient spot for you). The chassis will disipate all the heat.
If you attach your plate to the bottom (on the iside), you might attach additional panel of MDF, acrylic or whatever, on the other side to provide damping and "tune" the sound to your taste. The chassis itself might introduce to much unwanted resonances.
If you attach your plate to the bottom (on the iside), you might attach additional panel of MDF, acrylic or whatever, on the other side to provide damping and "tune" the sound to your taste. The chassis itself might introduce to much unwanted resonances.
There is a guy in Trading Post forum selling Vishay S102. Those might be a good choice for resistors as well, and would come cheaper than sourcing from other distributors. 20k value is still good for shunt and feedback and 1K will set slightly lower gain (but this may actually be what you prefer). At $3 a pc. those resistors represent a good value
Personally, I tried S102 for feedback and preferred Caddock, but your chassis may sound different and your taste might be different too, so it's definitely worth a try.
Personally, I tried S102 for feedback and preferred Caddock, but your chassis may sound different and your taste might be different too, so it's definitely worth a try.
Peter Daniel said:
Using full size chassis is probably not the best approch (just ask Bricolo
Mines works good
It has been heavilly tested during the new year party here (full power into 92dB 4Ohm speakers
)In such cases, the big chassis can be usefull to dissipate the heat, since there's no heatsink
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.