Tell us you use V class from the start! That is why your offset is a bit. Same % DVM accuracy matching in them VS a BL means more gross difference. Its OK for 2SK170V. Use 10K log if you can with your sources Zo. 10VDC is my recommended ballpark, why you wanna go 11? Nice to see your links in a while, and learn more when in final system. Congrats.
Oh sorry for not mentioning that I've got high IDSS ones before, I totally forgot 
I've no specific reason other than the THD vs Supply voltage graphs from the original B1 thread - someone played with that there and posted the results. It doesn't really matter to me as long as I'm over 9v per rail, really.
And as far as my listening session went - it sings
. It definitely gives more life to my system and I can't wait to put it in a box and enjoy it properly.
I've no specific reason other than the THD vs Supply voltage graphs from the original B1 thread - someone played with that there and posted the results. It doesn't really matter to me as long as I'm over 9v per rail, really.
And as far as my listening session went - it sings
. It definitely gives more life to my system and I can't wait to put it in a box and enjoy it properly.
That someone looking for a sweet spot maybe was me.😀 Maybe another one again, I don't follow it much. Listen to some, you got another Idss, maybe a better spot to find.
the sweet spot voltage for a Vgrade could well be different to a BLgrade.
I suspect it could be at a lower voltage, or the same as Salas found, or higher.
I suspect it could be at a lower voltage, or the same as Salas found, or higher.
I wish I could run a distortion analyser and a lab power supply, in order to experiment, but I'm afraid I'll just have to base it on my ears.
I got the voltages to +-11.17, kind of accidentally similar. As I said, it's hard to know without proper measurements, but if anything - it definitely doesn't sound worse. I lost a small amount of DC offset, not enough to matter and totally by accident.
The "Do my neighbours hate me yet" test says it all though - with the DCB1 I don't lose any detail at glass-shattering volumes. That makes me very very happy indeed. It's a clear step forward from what I used to have.
I also mounted the heatsinks properly, with some good thermal grease. They're nowhere close to being hot and they're tempting me to parallel another 51r at the last position 🙂 No, no - I promise, it's going in the box now, no more soldering for this board!
The "Do my neighbours hate me yet" test says it all though - with the DCB1 I don't lose any detail at glass-shattering volumes. That makes me very very happy indeed. It's a clear step forward from what I used to have.
I also mounted the heatsinks properly, with some good thermal grease. They're nowhere close to being hot and they're tempting me to parallel another 51r at the last position 🙂 No, no - I promise, it's going in the box now, no more soldering for this board!
Sorry Trip, I don't know.
I found it impossible to tell if adding the DCB1 made any difference to the overall sound output.
I found it impossible to tell if adding the DCB1 made any difference to the overall sound output.
DCB1 UPDATE
A few days ago, i replaced the CCS resistors with Mills MRA-12 resistors.
2.09v/3.9ohm= 535ma
1.73v/3.5ohm= 494ma
I was previously running at about 350ma....
Well as expected once again i get an improvement in SQ 🙂
The soundstage seems huge on certain recordings, each musician is more easily decernable and can be followed with ease(good seperation) yet they gel and sound very musical. The bass also has gained weight and control and as a result also sounds musical...but the real supprise for me is the treble...Just easier to hear, and REAL sounding!! Adds alot to the experience.
I checked the heat of the mosfets after an hour of listening...fan running at 5v...the mosfets are now hot, but not burning...im easily able to hold my finger on them without having to move away.
HIGHLY RECOMMENDED...especially for those with the Blue Boards.
Alon
A few days ago, i replaced the CCS resistors with Mills MRA-12 resistors.
2.09v/3.9ohm= 535ma
1.73v/3.5ohm= 494ma
I was previously running at about 350ma....
Well as expected once again i get an improvement in SQ 🙂
The soundstage seems huge on certain recordings, each musician is more easily decernable and can be followed with ease(good seperation) yet they gel and sound very musical. The bass also has gained weight and control and as a result also sounds musical...but the real supprise for me is the treble...Just easier to hear, and REAL sounding!! Adds alot to the experience.
I checked the heat of the mosfets after an hour of listening...fan running at 5v...the mosfets are now hot, but not burning...im easily able to hold my finger on them without having to move away.
HIGHLY RECOMMENDED...especially for those with the Blue Boards.
Alon
as salas mentioned several posts back, the 9240 & 240 fets have low transconductance at the lower currents and work better when the current approaches a few amps.
has anyone tried using smaller die-size fets (maybe in isolated TO-220Fullpak case) instead which would have higher transconductance at lower currents (e.g. 100mA)? i know that this might require shaping the leads to fit the pcb holes, etc...
Some 220s have even less gm. Some about the same but with different capacitances. You will not avoid about the same type of gfs curves anyway. There is a reason why V Mos lend better to class A amps. Don't forget the mounting screw insulation if you experiment with any of steeper curves you may spot.
Should I put an input low-pass filter when I'm casing this, or there's no advantage? My chipamp has no filter right now, but I'm putting 220pf across the inputs, mostly to avoid clicks&pops from the crazy lighting in this house. I might plug it into something else though.
Pictures coming soon, I'm almost done.
Pictures coming soon, I'm almost done.
I had to rewire my 1950's house in Rhode Island to get rid of the pops. I had to ground all the outlets in the basement and then I had to run a whole new dedicated line with a new breaker to audio. I solved most of the problems that way, like problems with the refrigerator starting up and popping my speakers. There was still a super loud pop once in a while and I figured out it was from a piece of trash lightswitch that when I opened it up it was actually arcing dangerously. Replaced that one and everything was good.
Uriah
Uriah
Best pop killer is better switches and X1 caps across at the source of the pops. Once it pops it never stops 😀 at the receiving end totally.
Mine are with dimmers and SMPS that buzz nicely down into the audio band. Can't do anything about that either - rented place and all that. Not that I turn them off and on all the time or anything.
There is a kitchen exhaust fan that startles me some times with a crash bang transient through audio I want to blow up with C4 now you reminded me.
Last small feedback:
CSS was at 80-84 mA. CSS heatsink was awrm-ish. Shunt heatsink didn't get any heat. No wonder, given the transistors were eating ~30mA in total.
So, another 51ohm resistor in the last spot, raising the current to 120mA. Now the CSS isn't much warmer, the shunt is pretty competing in heat - Bingo 🙂
My miniature heatsinks are gonna handle that, no more.
5 more drill holes for the RCA and the power-on LED and done. Weekend is coming, perfect.
CSS was at 80-84 mA. CSS heatsink was awrm-ish. Shunt heatsink didn't get any heat. No wonder, given the transistors were eating ~30mA in total.
So, another 51ohm resistor in the last spot, raising the current to 120mA. Now the CSS isn't much warmer, the shunt is pretty competing in heat - Bingo 🙂
My miniature heatsinks are gonna handle that, no more.
5 more drill holes for the RCA and the power-on LED and done. Weekend is coming, perfect.