Bought a Dynakit Mark III, so I joined a couple forums. Popped the multicap can on the variac, so I have to replace that. Looks like a pretty sweet ride. I'll be looking for a match some time. Decided to look into cd players with a more vinyl projection since I got the Mark III and decided the 1541A DAC players would be a good start. Made the mistake of buying a Japanese Marantz CD40. SO, I'm batting .500. Been fooling with this stuff for years, got a set Altec VOTT's with the giant horns I picked up for a song some years ago. Have a couple other oddball mono amps. Particularly an ElectroVoice A20-C I'd like to find a match for. That's about it for now.
I have the A5's. It's been a labor of love, so to speak. Although love might be a little strong.��
Most Variacs are wired for a +15% boost at their maximum setting, so use a DVM to monitor the ACV
you are applying. Don't go over 115VAC for testing, as that's what they were originally designed for.
Your line will be more like 120VAC though, but hopefully it will be ok.
Try to get a 525VDC rated cap if you can. Original rectifier output voltage was +490VDC, but with a
120VAC line, it will be more like 511VDC. Some 550VDC rated caps are available, but make sure
the input capacitance is not large enough to overload the rectifier tube (usually 60uF max, but depends on tube).
Capacitors Archives - Dynakit Parts
you are applying. Don't go over 115VAC for testing, as that's what they were originally designed for.
Your line will be more like 120VAC though, but hopefully it will be ok.
Try to get a 525VDC rated cap if you can. Original rectifier output voltage was +490VDC, but with a
120VAC line, it will be more like 511VDC. Some 550VDC rated caps are available, but make sure
the input capacitance is not large enough to overload the rectifier tube (usually 60uF max, but depends on tube).
Capacitors Archives - Dynakit Parts
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Yea, i was going up slowly letting it cook for 20 minutes on each increase in voltage and when i got to 90V it started smoking. I had the variac set on the outputs that had been checked with a DMM. I'm going to use a different variac next time and keep a better eye on it. I hope the damage has already been done.
I bought it not working, but it's got the Yamaha board in it. Doesn't have the 1541A. So it's broke and the wrong chip. Paperweight.
Unless you are a real luddite (tubes don't count if you're in this forum), great digital replay is available for about $250 all in using a Raspberry Pi with a decent DAC HAT. That doesn't include a phone or tablet running an app to control the Pi.
The issue you might encounter is hum or noise from a tube amp being audible from high efficiency speakers like your VOTTs.
Steve
The issue you might encounter is hum or noise from a tube amp being audible from high efficiency speakers like your VOTTs.
Steve
@rayma This Capacitor would be the one to get? Thanks
I just want to try a cd player with a 1541A in it and my tube setup. Building my own DAC might be a little much at this point.
It's a typical estate sale find. Been sitting for years, etc.
I just want to try a cd player with a 1541A in it and my tube setup. Building my own DAC might be a little much at this point.
It's a typical estate sale find. Been sitting for years, etc.
If the cap cooked at 90VAC line, it was probably already bad, but also monitor the bias current
in the output tubes as you increase the line voltage. If that jumps up, turn the bias pot down.
If you can't turn down the bias current far enough, either the output tubes are bad/shorted,
or else the bias circuit has a problem and is not putting out enough negative voltage.
in the output tubes as you increase the line voltage. If that jumps up, turn the bias pot down.
If you can't turn down the bias current far enough, either the output tubes are bad/shorted,
or else the bias circuit has a problem and is not putting out enough negative voltage.
Do I want This Capacitor or This one? Or either one? Is the higher rated one twice as good?
I want to keep it as original looking as possible. Can I take the sticker off and polish it?
I want to keep it as original looking as possible. Can I take the sticker off and polish it?
Then monitor the DC voltage on the bias pot wiper as you turn up the Variac.
It should stay somewhere around -55VDC, depending on the tubes and
the adjustment of the pot. The bias circuit does not need to warm up
since it is fed only be a diode.
It should stay somewhere around -55VDC, depending on the tubes and
the adjustment of the pot. The bias circuit does not need to warm up
since it is fed only be a diode.
I would get the 550VDC, 600V surge one, the higher the voltage rating, the better, in this amp.
The paper sticker should come off, but don't get any solvents in the bottom of the cap's can,
where it could get inside and do damage.
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Well I'm committed (and committable?) now. Got the 550V on the way. I think Dynakit parts needs to upgrade to modern semiconductors for their site. I think I ordered 4 times before I got a hit.
My favorite speaker. 🙂 Mine started as A7, then got upgraded. I ran them on a little Dynaco ST-35 for awhile and was happy.
The theory at one point was that flac files would capture meta data better than wav files. I have both, though I usually rip CDs to flac. Either one seems to work equally well to my ears and eyes.
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