I hadn't thought about it.
One option is DIY Audio power supply boards on hand, all of them have been snapped as I was going to use them with packaged diode bridges.
I'm not so proud that it has to be DIY. Assembled / complete / turnkey is fine
. Looked through Glassware, eBay, Jim's, open to suggestions.
Goal is to drive a pair of F4 monoblocks.
Alex says he has matched in JFET's in GR, BL, V - I most often see BL recommended. The eBay source in California lists them by IDSS.
You want BL. 7-9 or so.
You want to use a regulated supply, not the diyaudio psu which is for power amps and unregulated.
The transformer question relates to the regulator used...it depends on how much voltage the regulator drops. Most regulators drop 3 volts or so, so if you are aiming for 24v rails you will want at least 28 or so before it hits the regulator. Common transformers are 24v secondaries which will give you 31v or so before regulation. Antek is a good choice. I would use 100va for a balanced build. Or two 50va if dual mono.
The super regulator billboard from the diyaudio store is good but it requires a cap bank and rectifiers before it as well. Also, it’s not the most inexpensive option. Nothing wrong with lm317/337 too. Easier and cheaper. I’ve used both with the ba3. Not sure the ba3 cared either way.
You want to use a regulated supply, not the diyaudio psu which is for power amps and unregulated.
The transformer question relates to the regulator used...it depends on how much voltage the regulator drops. Most regulators drop 3 volts or so, so if you are aiming for 24v rails you will want at least 28 or so before it hits the regulator. Common transformers are 24v secondaries which will give you 31v or so before regulation. Antek is a good choice. I would use 100va for a balanced build. Or two 50va if dual mono.
The super regulator billboard from the diyaudio store is good but it requires a cap bank and rectifiers before it as well. Also, it’s not the most inexpensive option. Nothing wrong with lm317/337 too. Easier and cheaper. I’ve used both with the ba3. Not sure the ba3 cared either way.
WARNING NEWBIE AHEAD!!! First build. Just wanted to Making a BA-3 pre amp with a Vicol audio Maya passive controller in it. I have a AN-0209 - 25VA 9V TRANSFORMER for the Maya. And a AS-1220 - 100VA 20V TRANSFORMER to power the BA-3 pre.
The first thing I made was a regulated power supply... It was a good learning lesson in soldering, and that is all its going to be good for. So I need another power supply. I was looking at the universal PSU in the diyaudio store,... but I see above that its not regulated, so It shouldn't be used for this pre.
Can I use the the TUBECAD PS-19 Bipolar Power Supply Kit?
If so, do I just order the 24v version?
Also I assume my chassis will be 2U for this, do I want the 1.5in or 2.5in heatsinks for the PS-19?
Any and all help is much appreciated, thanks in advance.
Rob
The first thing I made was a regulated power supply... It was a good learning lesson in soldering, and that is all its going to be good for. So I need another power supply. I was looking at the universal PSU in the diyaudio store,... but I see above that its not regulated, so It shouldn't be used for this pre.
Can I use the the TUBECAD PS-19 Bipolar Power Supply Kit?
If so, do I just order the 24v version?
Also I assume my chassis will be 2U for this, do I want the 1.5in or 2.5in heatsinks for the PS-19?
Any and all help is much appreciated, thanks in advance.
Rob
Ps-19 is ok. Any lm317/337 psu will do assuming the caps are 35v or greater. The psu will see 28 or so volts before regulation so you need a margin for safety.
Order the 24v version, the specified voltage is the output. 1.5” heatsinks are fine. Current draw and voltage drop is what heats up the psu and yours will be low. If 2.5” heatsinks will fit (measurements for the chassis or on diyaudio store) bigger is better...leaves room for future builds with more current needs.
If you can’t get the ps-19 (looks out of stock now) there are tons of lm317/337 regs on eBay or amazon. Lm317/337 is an adjustable regulator, output voltage can be changed with a pot. Just make sure they have 35v caps.
I have been learning how use the FFT function on my oscilloscope and if I am not mistaken it can be used to adjust the amount of 2nd harmonic introduced by using P3. I can see the fundamental frequency and the 2nd bump can be increased or decreased by adjusting P3. Anyone else tried doing the same?
I used that power supply in two BA3 FE units, it has been unavailable on that site for some time, is it back in stock?
Russellc
If you can see the H2 bump then by all means go for it! Most scopes (unless very expensive) don’t have a ton of vertical resolution, which is why you can’t see anything past the H2.
Thought I would pass the info along. Many more have scopes with FFT than distortion analyzers. With proper adjustments you can definitely see the second hump and P3 does control it. I can null it out almost completely turning one way and increase it the other way. Others need to play with the FFT function on their oscilloscopes and post their results to confirm. I do have an old HP 334A that is a work in progress, re-capping.
I have been using the FFT function on my 'scope in the past to look for harmonic distortion. In a 2A3 tube amp, I have used it to try to offset distortion in drive stage with the distortion in the output stage.
I could easily discern 2nd and 3rd harmonic well above the background.
However, with my scope (Rigol DS1052E), I only feel confident with regard to absolute value down to a little bit lower than -40dB. Can see relative changes for lower distortion values, however.
For solid state amps, I will probably try the PC sound card / audio interface route.
Best regards, Claas
I could easily discern 2nd and 3rd harmonic well above the background.
However, with my scope (Rigol DS1052E), I only feel confident with regard to absolute value down to a little bit lower than -40dB. Can see relative changes for lower distortion values, however.
For solid state amps, I will probably try the PC sound card / audio interface route.
Best regards, Claas
Gain feels like 12db or so to me (not 25db), I would say it’s pinched at the top end, bass is a little weak and loose...soundstage is big and diffuse. Good sense of air. Dynamics a bit soft. If it sounds like Iam describing tubes than you get the picture.
To me, it’s better for small scale, simple music than big, complicated material. It never sounds “hard” if you are concerned about that.
A lot of this depends on where P3 is set.
I have BA-3, jfet boz, B1 rev2, Salas DCG3 and Juma’s Current Mirror preamp. In general, I mostly listen to rock and in general I seem to prefer the preamps with a bit of feedback.
I would have .64 inches not counting a baseplate or any risers...
I'm assuming that I can only do the 1.5 inch heat sinks on the regulator.
Dude(ism):
It's just math. Interior height of DIYAUDIO store 2U chassis is 80mm. 2.54cm in an inch.
I get that, but I only have specs of 80mm on the internal dimension... I have the 2.5 and the 1.5... But I do not posses the baseplate or risers yet, and have not worked with those items... and have no idea how tall those variables are.
I have not used the baseplates or risers, and probably wouldn't with a 2U chassis. Just drill through the bottom plate.
Typically standoffs (is that what you mean?) are 1/4 or so. So you would probably be fine.
You definitely don't want the heatsink to touch the chassis unless it's isolated electrically with a mica or silicone insulator.
Honestly, it doesn't matter much. You can buy a 2" heatsink from Mouser or Digikey and use that instead if it's a deal breaker for you.
Typically standoffs (is that what you mean?) are 1/4 or so. So you would probably be fine.
You definitely don't want the heatsink to touch the chassis unless it's isolated electrically with a mica or silicone insulator.
Honestly, it doesn't matter much. You can buy a 2" heatsink from Mouser or Digikey and use that instead if it's a deal breaker for you.