I can't leave well enough alone...I've decided to go with a Jung reg for my BA-3 preamp. Wonder how it will compare to the LM317/337 in there now. Iam hoping for some improvement, not that the BA-3 needs it. Let's see if the 317/337 regs are really as bad as everyone says they are...
Stay tuned.
Stay tuned.
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Interesting you say that. Im seeing similiar on mine, one channel under 10mV and other channel fluctuating.
30 minutes is long time. When do you start listening to yours after power up?
Do you notice any sound differences from power up to 30-60mins later?
Just curious.
I leave mine on 24/7. Also, it sits about a foot under my f5 which is a space heater. So iam sure its picking up heat from the f5. The bias on mine is rock steady...the dc offset fluctuates with temp. So iam sure its differento once the f5 is warmed up. Bottlm line...i dont worry about it.
Nelson alludes to this in the article, but basically the whole point of attempting to zero the offset as best you can is to keep things as linear as possible. It's twitchy, and varies with temp. That's why the 10uF cap is there. 
But once warmed up it's pretty stable. I use mine everyday, it's a fantastic preamp. I need to make a build guide for it.
No, they are not as bad as some people believe, but I bet the Didden/Jung regulator will work really, fantastically well.
But once warmed up it's pretty stable. I use mine everyday, it's a fantastic preamp. I need to make a build guide for it.
Hikari1 said:
No, they are not as bad as some people believe, but I bet the Didden/Jung regulator will work really, fantastically well.
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They (LM317/377) are not bad, and they are definitely better than the 79xx and 78xx. I'm using the LT1085 and 1033. These are considered better than a LM327/337 pair. Without direct comparison, I couldn't say. I would love to hear your thoughts on the Didden/Jung regulator with this preamp. You thinking dual or mono supply?
Single supply. I have the super reg board populated and have done the math to get 24V out. I am using PD's 317/337 boards now. I should have it up and running soon, the super reg board board does not include rectifying diodes or a capacitor bank so I need to figure out what to put before the super reg board.
I think it's all going to depend on the PSRR of the BA-3 and how it reacts. The BA-3 is basically designed to be run with an UNregulated supply as a gain stage for an amp...I wonder if the design is really power supply dependent. I am not smart enough to know it's PSSR characteristics by looking at the schematic.
Attached is an interesting chart from Linear Audio...
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I converted the PD boards to just CRC, 2,200uf caps with 4x .47R resistors between.
Using a 24V transformer I am getting 33V after the PD boards...hoping to drop 8V in the supereg to get 24V out.
I got the supereg up and running last night but I am having some issues with the positive side. Most likely my fault. I'll try to get it worked out this weekend.
Using a 24V transformer I am getting 33V after the PD boards...hoping to drop 8V in the supereg to get 24V out.
I got the supereg up and running last night but I am having some issues with the positive side. Most likely my fault. I'll try to get it worked out this weekend.
Iam not really trying to drop voltage with the crc arrangement....just filter a little. The superreg needs at least a 5v drop to perform well. Iam dropping 8v. I think that will do.
I have the neg side up and running. I burnt the chip in the positive side so ill have to order a new one. Stupid mistake....I learned one should always print schematics and pcb layouts in color not bw. Accidently hooked it up to the ps backwards on the positive side.
Ill replace the caps and chip and hopefully it will be up and running in a few days.
Btw...everybody complains about the cost of jfets and such....the ad817 chip is $5 each! Ouch.
Well it is up and running with the superregulator. Iam now running 25v rails instead of 30v rails on the ba3. My first impression is a little more detail than the lm317/337 set up but i need to let it burn in a little. Ill follow up with my impressions in a couple of days.
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Maybe....iam running a little less bias right now too. Iam going to let it play for a couple days...maybe raise the rail voltage and bias. I can take it up to 28v rails and still have 5v of drop out. Right now iam noticing more detail and less slam and bass. But it sounds extremely good, just a bit delicate. Better detail on cymbals and piano sounds more true. But perhaps not as much drive and kick. Could be the bias and rail voltage. But iam going to give it some time before making a judgement.