It didn't explode....... YET (aka niges amp)

[Derek]

Keep doing what you are doing Nige even if it is just intuition some of the time as the results will speak for themselves, if the well is getting dry in terms of funding due to hits along the way on components and we need to increase projected costs for the optimized TVC then lets do it, no need for a cost benefit analysis here.

Very happy to add more funding as is will be one of the best investments in audio in many years.

As above, X2, no need to sleep. If a few bob extra is required, no problem, the emergency piggy bank will be rifled.

[jkeny]

I agree - you're doing a great job, Nige - the couple of times I heard it, the amp was a revelation - can't wait to hear the new revision

[Fran]

Same as the lads - I can't contribute much to this other than excitement and happy to commit funds as needed! You certainly shouldn't be out of pocket.

Fran

[nige2000]

pass no attention, must have been a little crabby this morning
late nights and early mornings having its consequences

on a good note
on the psu board the insulated reg and diode test results look promising (2amp)
the voltage drop on the diode is more like 0.7 and the prototype ones were 0.3ish but thats ok theres plenty of headroom the diode gets a little warm without heatsink but thats ok too



the amp with tvc is sounding great,
its going to be difficult to volume match vs other amps coz of the increased dynamics and it seems like the quieter bits are quieter and louder bits are louder like a bigger volume range

is 11 positions of volume control enough?

makes me wonder if everyone should have tvc on output rather than a preamp

[abraxalito]

isnt the issue that it shits on its own doorstep? and does not have the noise rejection capability? and the step down makes it shit less?

Yep that's one way of putting it - 'shitting' is directly related to how much output current, the step down reduces that.

is there any way of estimating where inductance and esr becomes a problem?

I do it subjectively, put my ear to the tweeter and see if it sounds like I can hear sounds coming from its surface. If so then the supply's not clean enough at HF.

[abraxalito]

Richard says using the 60v input on trafo for 30v ain't optimal so will have to revise the trafo anyhow

It ain't optimal but if you wanted to experiment with a bigger step-down then its worth trying. After all with a 30VA toroid you probably don't have too high DCR.

[nige2000]

i discovered after taking out the trim pot that output was 64v not 30v as it were before
the lesser voltage must have been down to the voltage divider+trim

in which case should the trafo primary be more than 60v?


dcr was 7.2ohm on 60v pri

hard to know what the optimal input voltage and what lm3875 gain should be

[tony]

Same as the lads - I can't contribute much to this other than excitement and happy to commit funds as needed! You certainly shouldn't be out of pocket.

Fran

Same here we be all on the same hymn sheet.Looks like a great result is very close. It sounded great way back at Gerry/Fran's Eist day so we all know we are getting something special at the end of the journey.

[nige2000]

Had an enquiry about joining the Group buy, is there anyone else interested before i start sourcing parts

[sima66]

I'm still very tempted and just to make sure that I understand correctly:

Is this amp like integrated with 11 points of volume control?
Is it possible to make it mono and use two, with double binding posts? Would two mono's be better, or not?
Amp would be able to power two sets of 57's connected in PARALLEL?