Andypairo, i did not test my PSU with the amp but i have a trafo 9 V, with 4,5 VA. Should that do the job?????
By the way, Franz told in a earlyer post that there is a voltage between pin 3 and ground during the warming-up time (till the relais switch on). My PSU worls fine, but i have no voltage between pin 3 and ground during the delay??
Do anybody know how that comes?
Do anybody know how that comes?
wim said:
Hi wim,
9V@4.5VA means 500mA maximum output current.
Depending on how conservative this rating is it might do the job (or not
).Since the voltage is substantially higher than filament voltage I think it is likely to work (if the voltage doesn't sag too much) but surely it is a border-line situation.
For better reliability I'd use a different trafo, ut that's just my opinion.
Cheers
andrea
Update time...
Well eventualy I saw on Franz' schematic that one can go up to a 12V tranny for the heater grid... ann I put a giant heatsink on the little LM317 as it was getting very hot before.
All done I smoke a bridge rectifier after a few minutes, no damage done as nothing was hooked up... I then realised that the Bridge was only suitable for LM3875, so I replaced it...
🙁
One channel she dead, other one, very soft and humming... will have to faulttrace the amp module it seems.
As I said in one of my posts I made an integrated amp using the valve buffer, including a pre-out... so with the amp module disconnected, I plugged it in to my REV C... I.e. just the valve buffer and the REV C.
I am very impressed with the combination... I thought the Rev C was too bright always, this is gone now, yet there is more detail at the top (seems strange), midrange is robust and smooth, and many small deformations in the sound which I always thought were due to my old speakers are now virtualy gone, and instead replaced with wonderfully resolved sound.
I don't even want to start about the stereo effect I'm hearing now...
At this point in time I am considering using the tubes I have to create a 6 channel Pre, will at least build another 2 channel one for sure. But I'd like to get much better PSUs/layouts etc.
Well eventualy I saw on Franz' schematic that one can go up to a 12V tranny for the heater grid... ann I put a giant heatsink on the little LM317 as it was getting very hot before.
All done I smoke a bridge rectifier after a few minutes, no damage done as nothing was hooked up... I then realised that the Bridge was only suitable for LM3875, so I replaced it...
🙁
One channel she dead, other one, very soft and humming... will have to faulttrace the amp module it seems.
As I said in one of my posts I made an integrated amp using the valve buffer, including a pre-out... so with the amp module disconnected, I plugged it in to my REV C... I.e. just the valve buffer and the REV C.
I am very impressed with the combination... I thought the Rev C was too bright always, this is gone now, yet there is more detail at the top (seems strange), midrange is robust and smooth, and many small deformations in the sound which I always thought were due to my old speakers are now virtualy gone, and instead replaced with wonderfully resolved sound.
I don't even want to start about the stereo effect I'm hearing now...
At this point in time I am considering using the tubes I have to create a 6 channel Pre, will at least build another 2 channel one for sure. But I'd like to get much better PSUs/layouts etc.
A rectifier suitable for a LM3875 should stand about 6A current. And your tubes are drawing between 300mA to 450mA heather current.
What type of bridge did you use? EDF1B? Should be O.K. for opamps and heather for one tube. But never for a LM3875.
Kind regards
Franz
BTW: better use a lower voltage tranny for cool operating of the regulator.
Hey Franz, I think you misunderstood, I smoked the bridge driving the 2 LM3886's, it was only good for 4A... It still works, but it started to smoke, and got a little wet...
The valve buffer is working beautifully off my VSPS's Transformer, just haveing a hard time deciding which tube I like the best, each one does something else to the music I like...
Many thanks Franz
The valve buffer is working beautifully off my VSPS's Transformer, just haveing a hard time deciding which tube I like the best, each one does something else to the music I like...
Many thanks Franz
Thanks for your answer andrea, i will have to tray......
Thanks Franz, i tought you meant pin 3 of the sub D.
Thanks Franz, i tought you meant pin 3 of the sub D.
Where you driving your gainclones hard when the bridge started to smoke. If not I would suspect instability somewhere. At low power levels or idle the LM3886 wll draw very little current. Have you got grid stoppers on your ECC88's. These valves are prone to radio pickup if they don't have grid stoppers. You might be handing a high power radio signal to your LM3886 which will be working very hard.
Shoog
Shoog
Yep, shoog, I came to the same conclusion... 😱
It was not supposed to be drawing current like that, had no input or load on either. I decided to rip the amp module and convert the unit to a buffer only for my REV C, (which it does beautifully,) keeping the input selectors and pot... this will leave me some real estate in the case for future mods and tube learning or even a few more channels.
It was not supposed to be drawing current like that, had no input or load on either. I decided to rip the amp module and convert the unit to a buffer only for my REV C, (which it does beautifully,) keeping the input selectors and pot... this will leave me some real estate in the case for future mods and tube learning or even a few more channels.
Been thinking this one over a bit....
In order to place the two chips a bit further appart and get more even heating on the heatsink, could you not move the the voltage doubler to above the 6V supply and then move everything around clockwise into the empty space?
In order to place the two chips a bit further appart and get more even heating on the heatsink, could you not move the the voltage doubler to above the 6V supply and then move everything around clockwise into the empty space?
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