There are lots of options. What level boards and BOM are you using?
Input caps can tailor the sound character, but many would argue that DC coupled is the most accurate representation of the input signal. Are you happy with DC coupled? Are you considering an input cap for more protection or to change the character?
Jac
Thanks for your reply. I am not unhappy with the sound when DC coupled, I was just interested to see if adding caps might change the character of the sound.
I have fitted some 1uf Sonicaps but the jury is out at the moment on the SQ. I have some 4.7uf Sonicaps and some ICW polyprop 3.3uf ( I think that ICW are now ClarityCap?), but wondered if I should be shooting higher in quality or maybe different dialectric.
My boards are the Twisted Pear Red Ver 1.2.
I have fitted some 1uf Sonicaps but the jury is out at the moment on the SQ. I have some 4.7uf Sonicaps and some ICW polyprop 3.3uf ( I think that ICW are now ClarityCap?), but wondered if I should be shooting higher in quality or maybe different dialectric.
My boards are the Twisted Pear Red Ver 1.2.
Those boards are earlier than I was involved, so maybe some of the others guys that worked with those boards would be able to suggest something specific. I would say that larger than 1 uF are really not necessary, but of course they will work.
From what I remember about Sonicaps on Fremen Edition boards, they are only OK, but there were better choices even at low cost. If you can find Sprague V-735P (out of production, but around) or the Russian K71-4 (styroflex), my memory is that they were better detailed and still neutral. The current industrial BOM Cornell Dublier 940C is neutral and a step up from them. For a warm sound, I personally like the K75-10 with a 1 nF bypass cap, but Dario doesn't care for those at all, so it all depends on your taste. The previous FE BOM used the Mundorf Supreme that I like for it's dynamic sound and the new BOM uses the Auracap XO. All of these are inexpensive to moderate price, but you can play with lots more expensive caps if you want.
At some point, I would love to convince you to step up to a newer FE build. There has been continuous development of both components and pcb layout that have resulted in a truly superior sound, even though the circuit diagram is the same as your TP boards.
Jac
From what I remember about Sonicaps on Fremen Edition boards, they are only OK, but there were better choices even at low cost. If you can find Sprague V-735P (out of production, but around) or the Russian K71-4 (styroflex), my memory is that they were better detailed and still neutral. The current industrial BOM Cornell Dublier 940C is neutral and a step up from them. For a warm sound, I personally like the K75-10 with a 1 nF bypass cap, but Dario doesn't care for those at all, so it all depends on your taste. The previous FE BOM used the Mundorf Supreme that I like for it's dynamic sound and the new BOM uses the Auracap XO. All of these are inexpensive to moderate price, but you can play with lots more expensive caps if you want.
At some point, I would love to convince you to step up to a newer FE build. There has been continuous development of both components and pcb layout that have resulted in a truly superior sound, even though the circuit diagram is the same as your TP boards.
Jac
You might try searching the old MyRef C thread, in which a great many C13's were discussed. I tried quite a few in that older design, which sounded very good when properly built. The new Dario design is undeniably superior, but there was nothing wrong with MyRef C.
My favorite C13 back then was the Fostex cap, but the leads are large diameter and must be filed down to fit into solder pads. Sonicap gave a pleasant sense of 3D space, but with a slight loss of clarity in the highs. Almost any film and foil cap will perform better than almost any metalized plastic cap, but will cost more and be larger. The Audyn True Copper is superb, but its leads must also be reduced in size to fit.
Increasing the value of the cap much beyond 1uf will not yield significant, if any, improvement.
My favorite C13 back then was the Fostex cap, but the leads are large diameter and must be filed down to fit into solder pads. Sonicap gave a pleasant sense of 3D space, but with a slight loss of clarity in the highs. Almost any film and foil cap will perform better than almost any metalized plastic cap, but will cost more and be larger. The Audyn True Copper is superb, but its leads must also be reduced in size to fit.
Increasing the value of the cap much beyond 1uf will not yield significant, if any, improvement.
Thanks for your reply. It is fairly inexpensive to play with caps so I will try some more. So far as building another variant like the FE edition, it took me 14years to finally finish the TP boards...so.....the journey may be longer than the years left on this planet
The most current BOM and build guide are on Google Drive, as linked in each GB starting post:
My_Ref FE - BOM (From v1.5 boards) - Google Sheets
My_Ref_FE - Tutorial.pdf - Google Drive
-thanks- (new house/space and computer)... I can 'see' the list, 'google drive'. > cannot print out same. Should i sign up for 'Google' as my primary (browser?) forgive my lack of computer literacy. > 'let it go' for this moment. Am impressed w/design... and, have done early version of this amp. (only one channel worked). 'time flies'. I need a computer guy... (and/or a new advisor as to what works w/computer to print out info I'm looking for) ... I think i can get it after that. - thanks-
Private message me an email address and I’ll send you the Excel file. These forums don’t allow uploading Excel files through these posts.
Cheers, Pete
...inconsistency? is part of life. (and circuits). Finding the fault... is not! easy. I thank this forum...for consistent 'info'... that lets me troubleshoot. Hmm.. I've come across a 'pass labs' circuit. I've got a plus and minus supply of 22 volts... D.C. (from a P.A. system)... (with huge heatsinks) ...my 'thought' is that 'power supply' (surplus) might be better than using current power supply of a simple transformer putting volts out...rectified> to a chip amp. (w/diodes involved) (obviously ...these designs want about 22 24 26 volts (plus and minus + ground) And are designed? w/idea of that. Am I confused? would a simple plus and minus 22 volts D.C. work w/chip amp? (obviously, bypassing the diodes used in freman amp).
The Myref designs want to see +_35V power supply..
The FE has a limiter built in, which provides a controlled, smooth clipping at +_27,5V.
If the power supply is lower than +_35V, this limiter is not working any more.
It's not tragical, but You will hear a not nice clipping effect. And with low rails, that will happen frequently!
Also, the built in regulators in the FE would need a certain minimum headroom, above their output +_15V..
22V could be ok for that, but on the border..
Apart from this, chip amps like a pure LM3886 design, obviously work at lower voltages..
The FE has a limiter built in, which provides a controlled, smooth clipping at +_27,5V.
If the power supply is lower than +_35V, this limiter is not working any more.
It's not tragical, but You will hear a not nice clipping effect. And with low rails, that will happen frequently!
Also, the built in regulators in the FE would need a certain minimum headroom, above their output +_15V..
22V could be ok for that, but on the border..
Apart from this, chip amps like a pure LM3886 design, obviously work at lower voltages..
yes...was thinking of earlier 3886 design. (not freman) a pete daniels design? So, what would be best transformer for this iteration? (have a +/- 24 volt transformer) w/out rectification. But, perhaps that's too much? (And, i should start reading some more... i do not want to waste your time) The design i was referring had 'few parts' ...was from japan? And used the 3886 as the 'sum total'. (w/out any extraneous compensation). (maybe some protection for 'inrush') If I remember? It was when the chip was new?.... And it had So Few parts... (sold at 'retail' for 'big money') 'heat sinks and the simplicity of entire amp were unique.'
The my_ref series is actually quite different from other 3886 designs. To point you to some reading, please read the project_my_ref.pdf found on this page. It is in Mauro's own words.
Student's guide to myref
To answer your transformer question, transformers with 160VA per channel and 2 secondaries, either 2x25V (best for 8 Ohm speakers) or 2x24V, are recommended.
Student's guide to myref
To answer your transformer question, transformers with 160VA per channel and 2 secondaries, either 2x25V (best for 8 Ohm speakers) or 2x24V, are recommended.
The amp you're referring to is the Lab 47 Gaincard, the one that originated all the Gainclones. (Review here)
A lot of time passed and much better chipamps are out of there, the My_Ref and even better the My_Ref Fremen Edition are among the best ones.
The My_Ref is a composite amp where a high precision/low distortion opamp drives a power opamp.
Power opamps have not as good performance (both perceived and measured).
Your choice but this is not the right thread for it.