Here is my build so far, repurposed Originae X10 HTPC Case. Even though it was a horrible and loud system the build quality is amazing, front plate looks machined from a single inch thick aluminium block.
Front and back will have new plates cnc'd at my brothers work.
Original idea was to have the buffalo dac, MyRef and Tortuga pre all in one case. But its going a very tight build considering there will be 2 x shielded 225va, 2 30va and 1 maybe 2 15va transformers.
And thats just to fit it all in, i still have to worry about hum and noise between it all. Could very well go separates instead.
Front and back will have new plates cnc'd at my brothers work.
Original idea was to have the buffalo dac, MyRef and Tortuga pre all in one case. But its going a very tight build considering there will be 2 x shielded 225va, 2 30va and 1 maybe 2 15va transformers.
And thats just to fit it all in, i still have to worry about hum and noise between it all. Could very well go separates instead.
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Cool project. Just curious, what is that black thing in the middle?
Some of the guys who wanted small cases have built their amps as a double decker. Have you considered that? It's not as good as separates for hum control but it seemed like having a "floor" between the transformers and electronics provide both space efficiency and some hum isolation.
Keep up the good work and the pictures.
Just one note... you mounted C13 with different orientation among the two boards.
If you can easily desolder one of them use this orientation:
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The black thing is a fan assisted heatsink, I understand the amps are rather efficient but i needed to find a solution to cool the psu's which will be stacked. With the fan close to the psu's they should cool adequately.
There a million things that have to be done before i put this in a case/s. All the psu's are tested and working fine, the IVY stage i believe to be working fine but will soon find out when i have the dac running.
The waveio has been shipped, as for its power supplies i have options. I have a Placid HD and Placid HD BP. The bipolar can supply power to both input and output of the waveio. Should i be concerned they will then share the same ground?
The Placid HD could be used for powering the fan and with its trim pots i am able to control the speed.
There a many areas that i have no knowledge and everyone's advice will be greatly appreciated.
Ryan
Just one note... you mounted C13 with different orientation among the two boards.
If you can easily desolder one of them use this orientation:
I will put it on my to do list.
@ Feckie: Along with Jac's suggestion - I can't see how tall your chassis is, but if you have the room a simple shield for the transformers would allow dual level at the rear of the chassis only. The shield/shell if thick enough will allow threaded standoffs for mounting the amp modules to the top. I assume your brother could make that piece also at his work.
The amps require much less heatsink than most would assume. See posts #1316 - 1317 for a 3" x 4 " PC CPU heatsink that is handling two FEs. Also consider mounting the HS externally. That can be done by either making a cut-out in the back panel, or simple surface to surface with some through bolts - some thermal paste applied between the plates.
The transformers can be really close to the amps as shown in those same posts. Your wiring will have a bigger influence on hum production.
The amps require much less heatsink than most would assume. See posts #1316 - 1317 for a 3" x 4 " PC CPU heatsink that is handling two FEs. Also consider mounting the HS externally. That can be done by either making a cut-out in the back panel, or simple surface to surface with some through bolts - some thermal paste applied between the plates.
The transformers can be really close to the amps as shown in those same posts. Your wiring will have a bigger influence on hum production.
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Yes and no 
6L6 had it for a month. He called it the best LM3886 amp he has heard but is apparently still working on what he wants to post. Told me he did do some lab tests. He is doing a million things so I'm sure a report will show presently.
Uriah got the amp just over a week ago. I wouldn't expect to hear from him for a couple more weeks. He is rebuilding an LDR attenuator for his major audition.
They tell me the best way to learn patience it to practice it. 🙄
6L6 had it for a month. He called it the best LM3886 amp he has heard but is apparently still working on what he wants to post. Told me he did do some lab tests. He is doing a million things so I'm sure a report will show presently.
Uriah got the amp just over a week ago. I wouldn't expect to hear from him for a couple more weeks. He is rebuilding an LDR attenuator for his major audition.
They tell me the best way to learn patience it to practice it. 🙄
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I have a pair of Alpair 10.2s (7 Ohm) in Pensil enclosures, and a pair of 24V R-core transformers.
The Peter Daniels Gainclone is too loud in standard configuration. Am almost done with the FE's. Would it make sense to I use a resistor bridge to lower the DC before the rectifier diodes in order to lower the volume?
I'm no expert in this area. In any area, actually. But I don' t think lowering the transformer voltage would be a good idea. Is that what you meant by the resistor bridge? Also, I don't think it would change the gain of the amp.
If the gain of the amp is too high for the efficient speakers, then I would either reduce the gain of the amp (with risk to sound quality, nobody has tried it, to my knowledge), reduce the output of your volume control, or reduce the sensitivity of the speaker with an L-pad on the input of the speaker. The L-pad costs more with quality components and may affect the Qts of the bass speaker.
To me, it sounds like the best way is to reduce the output of the volume control. What are you using as a "pre"?
If the gain of the amp is too high for the efficient speakers, then I would either reduce the gain of the amp (with risk to sound quality, nobody has tried it, to my knowledge), reduce the output of your volume control, or reduce the sensitivity of the speaker with an L-pad on the input of the speaker. The L-pad costs more with quality components and may affect the Qts of the bass speaker.
To me, it sounds like the best way is to reduce the output of the volume control. What are you using as a "pre"?
Hey (to) lehmanhill - i have a good grasp (i think..) of indervidual driver L-pad attenuation post crossover at the driver terminal to match sensitivity of drivers and maintain DC impedance.... but does such voltage division work quite as eloquently pre crossover ??? - (whichever thing we conclude it dosnt seem like the eloquent solution for the reasons you mention alone...)
A MYREF'S feed back design (and hence gain) is really not simple to play with - im assuming looking at the compensation / and the intrinsic nature of the transfer function and its gain bandwidth product - and how this imparts its SQ..... just avoid (need to re read up on this - but some one feel free to butt in and give me the salient points)
- diminiising the DC of any part of the amp - wont change the gain - its designed for AC gain only - (less/more dc anywhere will hopefully be ignored - ish - on output)
Just for some numbers - is the Peters Daniels is a gain of 23 ? - the Fremen being 31, - 2.6 dB higher. Which is not huge (psychoacousticly 8dB is a doubling in percived loudness).
I have asked about chopping the input signal via a voltage divider in an earlier post and appreciate why it wasnt addressed -
I questioned effects in terms of noise using a high resistive values - it has a direct effect on frequency response with the input filter too - and concluded that on paper a pair of prohibitively expensive bulk films (imitating a pasive steped attenuator setting) of some 10K +10k to form in a 50% divider would be ideal to scale the input signal and not present a rediculously decreased filter product (or perhaps some affordable tantaliums (Shinkoh) ) - changing the input filter (low pass) is also not discussed - but is arguably trivial. Someone shed there views please....
- on a simpler fun note - my bespoke transformers, (shielded and overwound on overspec resin impregnated cores) came in the other day - yippieee!!!😛
A MYREF'S feed back design (and hence gain) is really not simple to play with - im assuming looking at the compensation / and the intrinsic nature of the transfer function and its gain bandwidth product - and how this imparts its SQ..... just avoid (need to re read up on this - but some one feel free to butt in and give me the salient points)
- diminiising the DC of any part of the amp - wont change the gain - its designed for AC gain only - (less/more dc anywhere will hopefully be ignored - ish - on output)
Just for some numbers - is the Peters Daniels is a gain of 23 ? - the Fremen being 31, - 2.6 dB higher. Which is not huge (psychoacousticly 8dB is a doubling in percived loudness).
I have asked about chopping the input signal via a voltage divider in an earlier post and appreciate why it wasnt addressed -
I questioned effects in terms of noise using a high resistive values - it has a direct effect on frequency response with the input filter too - and concluded that on paper a pair of prohibitively expensive bulk films (imitating a pasive steped attenuator setting) of some 10K +10k to form in a 50% divider would be ideal to scale the input signal and not present a rediculously decreased filter product (or perhaps some affordable tantaliums (Shinkoh) ) - changing the input filter (low pass) is also not discussed - but is arguably trivial. Someone shed there views please....
- on a simpler fun note - my bespoke transformers, (shielded and overwound on overspec resin impregnated cores) came in the other day - yippieee!!!😛
Thanks Lehmanhill. What I meant was indeed to lower the FE's input voltage by putting resistors (probably in L-configuration) between it and the transformers.
Currently my pre is Uriah's Lighter Note which works beautifully but is not too precise when attenuating volumes at late-and-quitet-night listening levels and I can't use the whole attenuation range because it gets too loud at ca 1/2 a turn of the knob. With the regular Gainclone playing with the feedback R eased the issue, but I'd rather not change the component values of the FE.
Have some of Uriah's resistor replacers lying around, might build an L-circuit with these to further attenuate the signal.
Currently my pre is Uriah's Lighter Note which works beautifully but is not too precise when attenuating volumes at late-and-quitet-night listening levels and I can't use the whole attenuation range because it gets too loud at ca 1/2 a turn of the knob. With the regular Gainclone playing with the feedback R eased the issue, but I'd rather not change the component values of the FE.
Have some of Uriah's resistor replacers lying around, might build an L-circuit with these to further attenuate the signal.
the trannies
My bad -I'm amazed- it seems adjustable wiper/pot/L-pads are actually commonly used at speaker inputs - I though you just used a L-pad calculator and hard wired them …… - seems horrible idea…
Anyways here’s my ridiculous traffo pair 😱 - 300VA mid bass - 100VA tweeter …
Also I have a quite specific question - the c34 27pf Mica caps are not available from Mouser for ages -(5982-08-100V27-F Mica Capacitors 27pf 100V 0805 5%)- and only via the US special postage (£) from Farnell, does any one have a suitable alternative till these are back in stock??
My bad -I'm amazed- it seems adjustable wiper/pot/L-pads are actually commonly used at speaker inputs - I though you just used a L-pad calculator and hard wired them …… - seems horrible idea…
Anyways here’s my ridiculous traffo pair 😱 - 300VA mid bass - 100VA tweeter …
Also I have a quite specific question - the c34 27pf Mica caps are not available from Mouser for ages -(5982-08-100V27-F Mica Capacitors 27pf 100V 0805 5%)- and only via the US special postage (£) from Farnell, does any one have a suitable alternative till these are back in stock??
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Also, you might try a polystyrene in this value. I remember that hificollective has small surplus polystyrene at a reasonable price.
As for the L-pad at the input of the crossover, I agree, they are not an elegant solution and risk negative effects on the sound. I don't know enough about the Lighter Note, but my memory is that it doesn't add any gain, just attenuates. That does make it tricky to reduce the signal level without screwing things up from an impedance standpoint. I think ElEsido's idea of trying Uriah's resistor replacer is a good idea, especially since he has them.
As for the L-pad at the input of the crossover, I agree, they are not an elegant solution and risk negative effects on the sound. I don't know enough about the Lighter Note, but my memory is that it doesn't add any gain, just attenuates. That does make it tricky to reduce the signal level without screwing things up from an impedance standpoint. I think ElEsido's idea of trying Uriah's resistor replacer is a good idea, especially since he has them.
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