electrolytics should be re-formed before use.
I think "in circuit reforming" is mistaken by some as breaking in.
Reform first and there is virtually no change in parameters after assembly.
I have been busy.... finished my BA-3 as a preamp on wood and listening to it.
Now all must be put in a nice enclosure
Some things I noticed:
- the gain is about 20 - 23 dB and not 30 dB at 24.0V rails. Doesn't mind I wanted it lower.
- the adjustment is a bit 'different' then with F5, the P1 and P2 pots don't influence each other as much as they do in a F5. You can bias both halves more individually...
- with these additional gain I start hitting the noisefloor... with the chain DAC--volumecontrol--DCB-1---BA-3---AlephJ I can now hear al little noise coming from the tweeters with my ear against them
Maybe when they are in metal enclosure it will be a bit better.
- better use multi turn potmeters!
I already have an input selector at the volume control board, so I'm going to use the extra free input relais on the Mezmerize board for switching between outputs of DCB-1 and BA-3 and probably BAF2013 Pre from Juma.
For normal listening I don't need amplification out of my pre and I will use the DCB-1.
Questions:
Is it appropriate to increase the input resistor to ground of the BA-3 from 47K to 220K like DCB-1. So it matches better with my 23K output impedance volume control?
For signal wiring ZM advices twisted CU, as thin as possible, but solid core or stranded?
I removed the 100E at the output of the BA-3, can I now use the BA-3 as a headphone amp? Like to have that feature on my preamp
When I ever want to build the BA-3 PP output stages, is it smarter to have 32V rails so I can have more voltage swing?
Thanks!
Now all must be put in a nice enclosure
Some things I noticed:
- the gain is about 20 - 23 dB and not 30 dB at 24.0V rails. Doesn't mind I wanted it lower.
- the adjustment is a bit 'different' then with F5, the P1 and P2 pots don't influence each other as much as they do in a F5. You can bias both halves more individually...
- with these additional gain I start hitting the noisefloor... with the chain DAC--volumecontrol--DCB-1---BA-3---AlephJ I can now hear al little noise coming from the tweeters with my ear against them
Maybe when they are in metal enclosure it will be a bit better.
- better use multi turn potmeters!
I already have an input selector at the volume control board, so I'm going to use the extra free input relais on the Mezmerize board for switching between outputs of DCB-1 and BA-3 and probably BAF2013 Pre from Juma.
For normal listening I don't need amplification out of my pre and I will use the DCB-1.
Questions:
Is it appropriate to increase the input resistor to ground of the BA-3 from 47K to 220K like DCB-1. So it matches better with my 23K output impedance volume control?
For signal wiring ZM advices twisted CU, as thin as possible, but solid core or stranded?
I removed the 100E at the output of the BA-3, can I now use the BA-3 as a headphone amp? Like to have that feature on my preamp
When I ever want to build the BA-3 PP output stages, is it smarter to have 32V rails so I can have more voltage swing?
Thanks!
Attachments
.....
Questions:
*
Is it appropriate to increase the input resistor to ground of the BA-3 from 47K to 220K like DCB-1. So it matches better with my 23K output impedance volume control?
**
For signal wiring ZM advices twisted CU, as thin as possible, but solid core or stranded?
***
I removed the 100E at the output of the BA-3, can I now use the BA-3 as a headphone amp? Like to have that feature on my preamp
****
When I ever want to build the BA-3 PP output stages, is it smarter to have 32V rails so I can have more voltage swing?
Thanks!
*why not
** solid core
*** if that suits your hearing apparatus , just go for it
**** yup
Walter,
Your the first person I have seen using a Jung Super reg with a Ba3 front end. If you dont mind sharing, how did you get 24V out if the super reg? Iam running lm317/337 at 32v rails but ive been looking at the super reg and waiting for someone to try it with the ba3. Id also be curious to see how you like it as a headphone amp. Are you going to put a switch in to bypass the 100r on output then another set of 10uf caps before the headphones or are you going to have a switch that just bypasses the resistor and run your headphone out after the 10uf caps?
Your the first person I have seen using a Jung Super reg with a Ba3 front end. If you dont mind sharing, how did you get 24V out if the super reg? Iam running lm317/337 at 32v rails but ive been looking at the super reg and waiting for someone to try it with the ba3. Id also be curious to see how you like it as a headphone amp. Are you going to put a switch in to bypass the 100r on output then another set of 10uf caps before the headphones or are you going to have a switch that just bypasses the resistor and run your headphone out after the 10uf caps?
I have been busy.... finished my BA-3 as a preamp on wood and listening to it.
Now all must be put in a nice enclosure
Some things I noticed:
- the gain is about 20 - 23 dB and not 30 dB at 24.0V rails. Doesn't mind I wanted it lower.
- the adjustment is a bit 'different' then with F5, the P1 and P2 pots don't influence each other as much as they do in a F5. You can bias both halves more individually...
- with these additional gain I start hitting the noisefloor... with the chain DAC--volumecontrol--DCB-1---BA-3---AlephJ I can now hear al little noise coming from the tweeters with my ear against them
Maybe when they are in metal enclosure it will be a bit better.
- better use multi turn potmeters!
I already have an input selector at the volume control board, so I'm going to use the extra free input relais on the Mezmerize board for switching between outputs of DCB-1 and BA-3 and probably BAF2013 Pre from Juma.
For normal listening I don't need amplification out of my pre and I will use the DCB-1.
Questions:
Is it appropriate to increase the input resistor to ground of the BA-3 from 47K to 220K like DCB-1. So it matches better with my 23K output impedance volume control?
For signal wiring ZM advices twisted CU, as thin as possible, but solid core or stranded?
I removed the 100E at the output of the BA-3, can I now use the BA-3 as a headphone amp? Like to have that feature on my preamp
When I ever want to build the BA-3 PP output stages, is it smarter to have 32V rails so I can have more voltage swing?
Thanks!
BA3 it`s made to drive output stage to full swing, and 20 or 30dB for a line amp that`s too much . Too much gain to trow away with input pot.
9dB for line amp is ok in my book and you can lower the gain of the circuit with little experimenting and changing few resistor values, so you won`t have noise issues anymore.
It's in a post from Jan Didden how to adjust the Vout. Here in another thread post 174: http://www.diyaudio.com/forums/diyaudio-store/247281-super-regulator-18.html#post3807398
Be careful if you use AD825 it's 30V in max. AD 817 is 36V in max.
I did already remove the 100 Ohm cause it's not really necessary, just to make the BA-3 more foolproof
So I'm not doing anything with a switch. I haven't tried the headphone yet.
I'll let you know when I listened to it.
I know it's too much gain, I read the gain structure article
That's why I also want to build Juma's BAF2013 pre with 10dB gain and put it in my preamp too. And with the relays switch between the DCB-1, BA-3 or Juma's BAF2013
Maybe when the VFET adventures are over, eventually build some real heavy BA-3
It's in a post from Jan Didden how to adjust the Vout. Here in another thread post 174: http://www.diyaudio.com/forums/diyaudio-store/247281-super-regulator-18.html#post3807398
Be careful if you use AD825 it's 30V in max. AD 817 is 36V in max.
I did already remove the 100 Ohm cause it's not really necessary, just to make the BA-3 more foolproof
So I'm not doing anything with a switch. I haven't tried the headphone yet.
I'll let you know when I listened to it.
Thanks Walter. Must have missed that in the Super Reg thread...I may try it in the near future.
I like my BA-3. I too have noticed that the gain is overstated. I actually like it stock as I primarily use vinyl. It is a smooth, controlled and sophisticated sounding preamp I think. I would like to try it w/headphones someday.
In Nelson's article he states that the fairchild mosfes will need 1k pots, not 500 ohm. Thats probably your issue. You can add resistance to the existing pots or switch them out for 1k pots. Iam using fairchilds and 1k pots...biased up fine with turns to spare.
Also, if you are not running bl grade jfets or sketchy ebay jfets you may not get it to bias up.
If you have multi- turn pots, 2k will be fine. Or add a resistor in series, that should get you in the ballpark...
All the pot does is draw some current across it to get the jfet turned on, in the proper amount. What matters is the bias itself, not the value if the resistor that gets it going.
All the pot does is draw some current across it to get the jfet turned on, in the proper amount. What matters is the bias itself, not the value if the resistor that gets it going.
I tried one channel today using 5k pots, touchy but was able to adj. 1v across r10 & r11
curious so I measured P1 and P2, they were around 260-270 ohms. Dont understand why the 500ohm pots did not work.
I will put 1K's in there for final.
For P3 do you just leave it mid way? Or you have tried tweaking by listening if no
Distortion Analyzer available.
curious so I measured P1 and P2, they were around 260-270 ohms. Dont understand why the 500ohm pots did not work.
I will put 1K's in there for final.
For P3 do you just leave it mid way? Or you have tried tweaking by listening if no
Distortion Analyzer available.
Regarding p3, I dont have a scope or analyzer but to me it sounds best in the middle. I adjusted them both so the resistance was the same measuring across the resistors off the pot. Look at the schematic, you will see them. I just made sure they were equal and same channel to channel. This assumes you have matched jfets.
P3 effects bias and dc offset though so make sure you rebias when adjusting. If you look back at prior posts on this thread you will see i ran some probe wires off the board to easily test bias. I recommend doing that.
I tried other settings too...really changes the sound. Without a scope you just need to make sure the settings are same channel to channel and use your ears.