Yes, 1,3x seems to hit the ballpark under load, and 1,4 without load is most often pretty accurate.
Yup. Very nice. Unfortunately it too makes a minor buzz, so I fear there is a significant DC offset on the mains going on.
Hey, just a quick update.
I don't like leaving my questions I post without conclusions in case something in them is helpful to others. I had posted on 9/12, post 2413, some questions. The official conclusion to them is that I had one bad transistor in the cap mx section the SLB power supply which led to too high voltage on one rail. Overall, my power supplies deliver 34.2 volts instead of the 32 I was planning for, so I'm addressing that with a RC in series/parallel with each rail on the FE board to bring the voltage into a safer range. The voltage regulators I had bought on Amazon were too cheap and hardly reliable. Last, I had an odd pulsing noise coming from both output stages which was fixed after I replaced the output transistors. Maybe one day I will figure out which ones are bad out of the 12.
Anyway, enjoy some pics of my amp (with its art deco faceplate) and the system it is powering. Best bass so far from anything I own, dead slient with the Smooth as Butter power supplies, -extremely- transparent. Wide, deep soundstage. I can even hear the floor of the recording venues sometimes now! These speakers are not the highest end that I have, so there’s much more to discover. The preamp above it is a BA-3 FE as well.
I don't like leaving my questions I post without conclusions in case something in them is helpful to others. I had posted on 9/12, post 2413, some questions. The official conclusion to them is that I had one bad transistor in the cap mx section the SLB power supply which led to too high voltage on one rail. Overall, my power supplies deliver 34.2 volts instead of the 32 I was planning for, so I'm addressing that with a RC in series/parallel with each rail on the FE board to bring the voltage into a safer range. The voltage regulators I had bought on Amazon were too cheap and hardly reliable. Last, I had an odd pulsing noise coming from both output stages which was fixed after I replaced the output transistors. Maybe one day I will figure out which ones are bad out of the 12.
Anyway, enjoy some pics of my amp (with its art deco faceplate) and the system it is powering. Best bass so far from anything I own, dead slient with the Smooth as Butter power supplies, -extremely- transparent. Wide, deep soundstage. I can even hear the floor of the recording venues sometimes now! These speakers are not the highest end that I have, so there’s much more to discover. The preamp above it is a BA-3 FE as well.
I just realized this thread has been idle for almost 9 months. Is there some reason people aren't building BA-3s other than scarce Toshiba 2SJ313/2SK2013 FETs?
This looks like a nice amp, and I love my recently completed Aleph J, so I thought I'd try my hand at building the BA-3 single-ended version. I have a few questions from the perspective of a non-electronics guy...
It was mentioned in the guide that output resistors can be lowered from 1R to R68 or R47 to increase output, and that 32V rails will decrease distortion and increase power. So, is it safe to do both with a single-ended setup? I ask because I didn't see it specifically mentioned in the Build Guide. What other mods will I need other than 35V caps and large heatsinks? Will trim pot values remain the same? I also assume I should run both the input and the output stage at 32V - is that correct?
This looks like a nice amp, and I love my recently completed Aleph J, so I thought I'd try my hand at building the BA-3 single-ended version. I have a few questions from the perspective of a non-electronics guy...
It was mentioned in the guide that output resistors can be lowered from 1R to R68 or R47 to increase output, and that 32V rails will decrease distortion and increase power. So, is it safe to do both with a single-ended setup? I ask because I didn't see it specifically mentioned in the Build Guide. What other mods will I need other than 35V caps and large heatsinks? Will trim pot values remain the same? I also assume I should run both the input and the output stage at 32V - is that correct?
Which version specifically are you thinking of doing?
https://cdn.shopify.com/s/files/1/1006/5046/files/burning-amplifier-configurations.pdf
BA-3 front end with SE (BA-1) output?
You don't need the Toshiba parts for the BA-3 front-end, although many report that they are nice to use if you can get them. If not, there are plenty of common substitutes mentioned along with a change in the bias pot value (for the front end) depending on your choice. I built it both ways.
There's a ton of information in the BA-1 threads re: what you can do with the SE output stage. With that said, you should be totally fine lowering the source resistance with well-matched output devices and also running 32V rails.
https://cdn.shopify.com/s/files/1/1006/5046/files/burning-amplifier-configurations.pdf
BA-3 front end with SE (BA-1) output?
You don't need the Toshiba parts for the BA-3 front-end, although many report that they are nice to use if you can get them. If not, there are plenty of common substitutes mentioned along with a change in the bias pot value (for the front end) depending on your choice. I built it both ways.
There's a ton of information in the BA-1 threads re: what you can do with the SE output stage. With that said, you should be totally fine lowering the source resistance with well-matched output devices and also running 32V rails.
I suspect people are just excited about all of the other projects going on around here. This is a nice circuit.
If you can get a hold of the j313/k2013 fets, they do sound nice. However, I am sure you have seen that there are other replacements that are more of a standard. You are going to need a good source and speakers to hear the differences. Prakit sells them. Worth the investment to have them around.
Assuming complimentary, with 0R47 resistors, your matching on the 240/9240's needs to be closer than with the 1R. Doing both 0R47 and 32 volts rails should be fine as well so long as your matches are good. Measure the MV across the source resistors after it is fired up and see how closely they are behaving to one another. This will also confirm all mosfets are working
I believe Pass used 1R because he wanted to allow some grace for the DIY crowd in case the matching of their mosfets were not that close.
Rhthatcher has closely matched devices at a reasonable price. I don't know how closely the store matches their mosfets.
If the bias range of the pot on the bias board is too low (again assuming complimentary) increase R128 a bit but I suspect it will be fine.
If you can get a hold of the j313/k2013 fets, they do sound nice. However, I am sure you have seen that there are other replacements that are more of a standard. You are going to need a good source and speakers to hear the differences. Prakit sells them. Worth the investment to have them around.
Assuming complimentary, with 0R47 resistors, your matching on the 240/9240's needs to be closer than with the 1R. Doing both 0R47 and 32 volts rails should be fine as well so long as your matches are good. Measure the MV across the source resistors after it is fired up and see how closely they are behaving to one another. This will also confirm all mosfets are working
I believe Pass used 1R because he wanted to allow some grace for the DIY crowd in case the matching of their mosfets were not that close.
Rhthatcher has closely matched devices at a reasonable price. I don't know how closely the store matches their mosfets.
If the bias range of the pot on the bias board is too low (again assuming complimentary) increase R128 a bit but I suspect it will be fine.
Sorry, for clarity...
SE in these forums can mean two things...
Not balanced / Non differential
OR
What I'm meaning here.. The All N-channel single ended output stage vs. the complimentary stage.
Either way...
You can run lower source resistance with well-matched output devices, and 32V rails is no problem as long as you stay within the norms for dissipation / heat per device.
SE in these forums can mean two things...
Not balanced / Non differential
OR
What I'm meaning here.. The All N-channel single ended output stage vs. the complimentary stage.
Either way...
You can run lower source resistance with well-matched output devices, and 32V rails is no problem as long as you stay within the norms for dissipation / heat per device.
I'm getting the j313/k2013s from user prakit, who seems to be a reputable source from what I've read. I am getting the MOSFETs from Randy, as you suggested. Am I supposed to use all 240s for the SE setup, or should I use the complimentary pairs?
Thank you very much for your help!