Toshiba MOSFETs with a twist

[abraxalito]

think batt would go a long way on narrowing the sound gap between these two batt amps

WIth a classA amp (constant current draw) you can use what's called 'choke input' for a mains supply. But I've never designed one of these - needs a single very large choke. Probably too large to be practical. Next best thing is a CLCLCLC supply, I could look at designing one of those if you're interested. It would need a few large chokes (say PQ5050 cores) but each choke wouldn't have too many turns on it.

[nige2000]

think batt would go a long way on narrowing the sound gap between these two batt amps

WIth a classA amp (constant current draw) you can use what's called 'choke input' for a mains supply. But I've never designed one of these - needs a single very large choke. Probably too large to be practical. Next best thing is a CLCLCLC supply, I could look at designing one of those if you're interested. It would need a few large chokes (say PQ5050 cores) but each choke wouldn't have too many turns on it.

dunno what im doing yet
a dual mono battery supply the way i do it is pretty damn expensive
20 cells
20 charging circuits
2 transformers
ginormous case with huge heatsinks

ill probably rig up a temporary batt version thats transportable for now do some cross comparison and decide if its worth pursuing further

[nige2000]

Any idea how much power the HP amp uses?

Wondering how many amps of 16V I need for the power supply.

I was calculating the power rating required for R2, and I must be doing something wrong because I'm getting a very high power number.

If your tk50 uses 3.8A, the hp amp must be much less.

Randy

hp amp is set at 1.08 amps per channel, that then is constant
works reasonably well at 14+ v
i used it at 18-20v but more voltage is more heat

[randytsuch]

thanks Nige

Looks like I need a bigger R2 then. Going to go with a through hole one instead of sm.

[nige2000]

think its about 1.5 w dissipation on r2?
i used 7w 1r2 resistors their hardly even warm
generally see 3w resistors for power in these type of circuits

[randytsuch]

1.5 w sounds about right.
I went with a 3 watter

pwb8.JPG (77.5 KiB) Viewed 584 times

[nige2000]

richard
what's the reason that higher voltage on these class a circuits seem to sound better?

[abraxalito]

I can only guess that its because the parasitic capacitances of the MOSFETs decrease with more volts across them. Meaning you get better PSRR at higher voltages.

TK50J30Dcaps.png (70.94 KiB) Viewed 552 times

[randytsuch]

Hmmm. Higher voltage = more batteries and higher expense.

Sounds like you guys are making another run at my wallet lol

[nige2000]

i had suspected higher voltages were performing better on the batt ps with this speaker amp but i dont have what id call conclusive result as i havent been able to switch between different voltages quickly

i was muckin about last night with a 30v battery supply last night been charged and not been charged with a badly botched together ps
coincidently noticed if i connected the gain stage to lesser voltages 26.5v or 23v it didn't sound as good
its not something i noticed when not using the battery pack

on another note i have what i assume is a 50hz hum coming into the sound as soon as i power up the ps (well the ps is bad)
where during playback isnt particularly noticeable but what is easily noticeable is lesser dynamics less decay and finer detail
just thought the symptoms was interesting