I’ve acquired some of the same huge heatsinks that Vunce has used. I want to maximise the bias current (because the heatsinks can handle it) so I’m aiming for 1.5A as a minimum. Again similar to Vunce, I’m going dual mono with SLB power supplies, so I’m just wondering how high I could / should spec the voltage on the trafo secondaries. What would you recommend guys?Hi Tmas,
During my USSA5 build I used an Antek AN-2222 trafo with an SLB psu for the initial power-up, this combo was good for 26vdc under load. For my final assembly I used a pair of AS-3224 trafo’s with dual SLB’s, this combo yielded 27.5vdc@1.3A bias. My heatsinks are very large and handle the increased voltage without a problem.
If you planned your chassis with borderline heatsink size, I’d recommend a pair of 20v Antek trafos. If your HS are capable, a pair of 22v trafos should work great with a little extra OOMPH!
Good luck with your project, this is a wonderful amp Fab shared with us.
Cheers,
Vunce
Hi BG
if you read the description on the USSA-5 group buy thread you will get my impressions on the sound where soundstage is the forte of all the USSA amp Versions (mainly CFA topology). Separation of individual instruments usually comes at the same time with big soundstage and for me this is what I call “detailed“ as opposed to over bright tonal balance….Also for me “live character“ comes with soundstage and dynamic. Dynamics will also be limited by the rest of your elements in your sound system but USSA should not be the limiting factor… normally. The value parts is selected for good dynamics for this topology.
thanks for your appreciation of my contribution to the diy forum.
Fab
if you read the description on the USSA-5 group buy thread you will get my impressions on the sound where soundstage is the forte of all the USSA amp Versions (mainly CFA topology). Separation of individual instruments usually comes at the same time with big soundstage and for me this is what I call “detailed“ as opposed to over bright tonal balance….Also for me “live character“ comes with soundstage and dynamic. Dynamics will also be limited by the rest of your elements in your sound system but USSA should not be the limiting factor… normally. The value parts is selected for good dynamics for this topology.
thanks for your appreciation of my contribution to the diy forum.
Fab
Studley
these are very big heatsinks. I estimate they can dissipate about close to 120W at about 50C (with ambient temperature of 22C for example).
so P= VI. But before putting more than 50W into each To-264 mosfet package ensure you have a very good thermal interface between mosfet and heatsinks.
just a reminder that because of the increased class A envelope you do not need very high current to stay in class A…
Fab
these are very big heatsinks. I estimate they can dissipate about close to 120W at about 50C (with ambient temperature of 22C for example).
so P= VI. But before putting more than 50W into each To-264 mosfet package ensure you have a very good thermal interface between mosfet and heatsinks.
just a reminder that because of the increased class A envelope you do not need very high current to stay in class A…
Fab
Yes I know, just the 2 heatsinks weighs a lot! But they do look totally cool 😉Massive heat sinks... will take some strength to lift your amp.
hi Julien
please contact me by personal message for build manual.
As for USSPA2 question, it is not that clear to me….
.Fab
