I do plan to build a 5, but perhaps not until this winter. Life can be complicated and often there are other priorities that take our time. I have all the parts except the output mosfets. Is there a “best” specification type to order?
Right now I am struggling to finish a balanced preamp. Today I need to prepare for Hurricane Dorian which appears to be headed straight at us as a Cat 1. Last time that happened, with Juan in 2003, the resulting mess left us without power for nearly a week.
Right now I am struggling to finish a balanced preamp. Today I need to prepare for Hurricane Dorian which appears to be headed straight at us as a Cat 1. Last time that happened, with Juan in 2003, the resulting mess left us without power for nearly a week.
Fab, yes I didHi Ernst
You are welcome!
You have a very nice compact class A amplifier. You even have written the amplifier specification on the back panel !
Fab
. I wanted to let people, that might get its hand on it in a distant future, what they are having in hand. I have taken down your specs and in some close future I will measure my own version. I hope it comes close to your figures; looking at my USSPA measures I strongly think I'll do.
Cheers, Ernst
I wish you luck to get passed the hurricane without any damage or power loss...
For the output mosfet the Exicon double die “-S” suffix stands for selected. It assures you to have more similar amplifier open loop gain between left and right audio channels. But it is not mandatory since the difference may not be significant...
Fab
Thank you guys for your kind words.
For me as a rather messy person this is indeed a clean build, even the cables are rather just going from one point to another, without being guided separately. I have seen much more sophisticated cabled amps here and somehow I admire people for this particular ability and what it might mean.
I use a single 400W transformer, feeding a F7 style common C1, separated (for each channel) R and separated C2 PSU - pcb art done by Jeff Young. On the rear there is a speaker protection board.
I like this small formfactor, even it keeps me from building amps with more than 100 W dissipation. For this I build all in this dimension and some I can't build.
Cheers, Ernst
For me as a rather messy person this is indeed a clean build, even the cables are rather just going from one point to another, without being guided separately. I have seen much more sophisticated cabled amps here and somehow I admire people for this particular ability and what it might mean.
I use a single 400W transformer, feeding a F7 style common C1, separated (for each channel) R and separated C2 PSU - pcb art done by Jeff Young. On the rear there is a speaker protection board.
I like this small formfactor, even it keeps me from building amps with more than 100 W dissipation. For this I build all in this dimension and some I can't build.
Cheers, Ernst
Good start manniraj
For C2 you should use something better than the Wima. Use at the minimum the other indicated part number from Panasonic: ECW-FE2W475J. Even better to use ECW-FD2W475J. The latter part is quite good for the price. As you can see there is enough room on the pcb to put a lot bigger cap.
Fab
For C2 you should use something better than the Wima. Use at the minimum the other indicated part number from Panasonic: ECW-FE2W475J. Even better to use ECW-FD2W475J. The latter part is quite good for the price. As you can see there is enough room on the pcb to put a lot bigger cap.
Fab
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Looking good so far Manniraj,
I added the same R23-26 resistors to my Mouser order
For my USSA5, the power supply will be handled by a single transformer and SLB psu board.
Version 5.1....?
Hi
Maybe this should be an interesting version using darlington Sanken transistors (Q5/Q6) instead of the obsolete mosfet drivers...
Aside the driver change it requires some resistors changes. The idea comes from my FSSA2 amp. I was not convinced at first but playing with the simulator shows that it should work fine. Also, based on the similar sound between my FSSA1 and FSSA2 I believe it is worth the try. And the good thing is that the pcb stay the same (Fit Form Function)
Any Fearless Amplifier Builder ?
Fab
Hi
Maybe this should be an interesting version using darlington Sanken transistors (Q5/Q6) instead of the obsolete mosfet drivers...
Aside the driver change it requires some resistors changes. The idea comes from my FSSA2 amp. I was not convinced at first but playing with the simulator shows that it should work fine. Also, based on the similar sound between my FSSA1 and FSSA2 I believe it is worth the try. And the good thing is that the pcb stay the same (Fit Form Function)
Any Fearless Amplifier Builder
?Fab
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Hi Vunce
Results should be good with a cap multiplier.
However, have in mind that you need to consider the voltage drop thus select higher power transformer voltage accordingly. Of course a single transformer will require higher power for transformer.
Fab
All good tips Fab.
I’ve used a few different cap multipliers with class A builds in the past, but the SLB psu with the inclusion of an active rectifier and CRC works excellent! I use an Antek 400va, 2 x 20v trafo with my Alpha20 which has very similar power demands as the USSA5. This setup is good for 23.5vdc with each amp board drawing 1.3A, and totally silent background!!
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Thanks Fab, I have this cap - MKS2B044701K00KSSD WIMA | Mouser from the kit that I purchased. Let me check the ECW-FD2W475J and thanks for the heads up.
Hi Vunce
Definitely with active bridge, cap multiplier and CRC this is the best PSU
In fact the bias current requirement for USSA5 in class A should be less than for the ALPHA20 from my understanding. The USSA5 is push pull using mosfet with almost no degeneration increasing class A power. Therefore, +/- 23,5vdc with 1.3A is more than enough.
Fab
Definitely with active bridge, cap multiplier and CRC this is the best PSU
In fact the bias current requirement for USSA5 in class A should be less than for the ALPHA20 from my understanding. The USSA5 is push pull using mosfet with almost no degeneration increasing class A power. Therefore, +/- 23,5vdc with 1.3A is more than enough.
Fab
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