Check your top DMM. There is s trace between those two points, correct? If so, how would you have offset. 
You don't need two meters to read offset, just one. See other posts for where to put your probes. Small monitor, and I can't pull up your pic to ensure correct or modify your pic if not.
You don't need two meters to read offset, just one. See other posts for where to put your probes. Small monitor, and I can't pull up your pic to ensure correct or modify your pic if not.
Almost a year in the making...and still working on it. Muffsy I/O selector and Muses volume control using Apple remote for input switching, volume, and mute. Similar tone as my 01 preamp, but better attack provided that H2/H3 profile adjusted to my taste. A sleeper preamp that need more recognition imho. Playing Christmas carols......... Merry Xmas to all!
... Merry Xmas to all!
Hello, I hope everyone is doing well. I'm about to start gathering parts for a BA-3 FE to run an F4 and don't know which jfets I should use. If I build this to run off 24v at 8mA bias can I use a 7-8mA matched quad I already have (from punkydawgs) or do I need to get the 8-11mA from the store? I looked at the Idss choice page and just got more confused by what it said for the BA18 gain stage.
Hello,
how's xmas holidays going, how many pounds to get rid of?
I am reading the thread, got to page 30ish but I am no tech at all still finding interesting to read it as I am thinking to have a BA-3 built as a preamp to match to F4 which is at its beginning stage.
Being no tech I have a very skilled friend to perform construction, the F4 will take the place of a push pull of KT88 tubes driven by my old Audio Research SP9 (MKI version) which then gives voice to old JBL L220; I wanted to try a Solid State amp to drive the JBL and even tho many say that 25W won't even scratch the surface of such big drivers with a mere (...) 90db/W speakers I opted for the F4 which, as even stated by many on these forums, would be a great mate for my SP9 which outputs more than 20db to feed the F4.
Next step a preamp to mate the F4 so that I can move both the tubes amp and the SP9 to a second setup where my beloved JBL 4311b (yeah, I love JBL) need to throw their voice and stumbled upon this thread, I am reading about many who matched the BA-3 with the F4 with good results so my question being, am I gonna eventually get an improvement over the Audio Research preamp (given I won't need a phono section which I would eventually add in a separate box)?
The output of the BA-3 seems, from what I read, be about the same as the SP9 so they should both provide same pressure level off the speakers, I am still wondering if the 25W would do it, I run music with the volume knob never over 11 hours and the KT88 is supposed to be in the 50W range, am I correct that I won't get a drop in sound pressure with the BA-3 driving the F4 (and/or the KT88) vs the SP9?
I can see on the DIY store the BA-3 board and I seem to understand one would drive both channels, is it hard to find the FETs to populate the board? Which other components can I find on the store? I am trying to get down to an approx cost of the whole thing before I eventually start to dream about it.
I spoke about a SS preamp to the guy who's in charge of building the F4 but he disagrees, didn't tell him to check the BA-3 front end, he seems to like better a tube for a preamp, he didn't tell me why but I will eventually ask.
One last question, along with the BA-3 boards from the DIY store where can I find the PSU boards as well as other critical components?
Ok, time to find out how to burn the Panettone
Merry xmas everybody!!!
how's xmas holidays going, how many pounds to get rid of?
I am reading the thread, got to page 30ish but I am no tech at all still finding interesting to read it as I am thinking to have a BA-3 built as a preamp to match to F4 which is at its beginning stage.
Being no tech I have a very skilled friend to perform construction, the F4 will take the place of a push pull of KT88 tubes driven by my old Audio Research SP9 (MKI version) which then gives voice to old JBL L220; I wanted to try a Solid State amp to drive the JBL and even tho many say that 25W won't even scratch the surface of such big drivers with a mere (...) 90db/W speakers I opted for the F4 which, as even stated by many on these forums, would be a great mate for my SP9 which outputs more than 20db to feed the F4.
Next step a preamp to mate the F4 so that I can move both the tubes amp and the SP9 to a second setup where my beloved JBL 4311b (yeah, I love JBL) need to throw their voice and stumbled upon this thread, I am reading about many who matched the BA-3 with the F4 with good results so my question being, am I gonna eventually get an improvement over the Audio Research preamp (given I won't need a phono section which I would eventually add in a separate box)?
The output of the BA-3 seems, from what I read, be about the same as the SP9 so they should both provide same pressure level off the speakers, I am still wondering if the 25W would do it, I run music with the volume knob never over 11 hours and the KT88 is supposed to be in the 50W range, am I correct that I won't get a drop in sound pressure with the BA-3 driving the F4 (and/or the KT88) vs the SP9?
I can see on the DIY store the BA-3 board and I seem to understand one would drive both channels, is it hard to find the FETs to populate the board? Which other components can I find on the store? I am trying to get down to an approx cost of the whole thing before I eventually start to dream about it.
I spoke about a SS preamp to the guy who's in charge of building the F4 but he disagrees, didn't tell him to check the BA-3 front end, he seems to like better a tube for a preamp, he didn't tell me why but I will eventually ask.
One last question, along with the BA-3 boards from the DIY store where can I find the PSU boards as well as other critical components?
Ok, time to find out how to burn the Panettone
Merry xmas everybody!!!
Thanks Dirk! The display says it all "1-4-3". I had been using the BA-3 FE for quite sometime now even when I only have it in skeletal (plywood board) build. After adjusting the H2/H3 profile, I realized how powerful this preamp can be, thus I invested in a decent case and other components to support it. Very happy with this preamp! Playing with H2/H3 combo is the key to "opening" the preamp's capabilities in my experienced.
The (genuine) Toshiba devices (2sk2013, 2sj313 are still available from.
https://www.diyaudio.com/community/members/prakit.24874/
Send a p. m. on here.
Jfets from the store.
Anything on E-bay is likely to be fake!
https://www.diyaudio.com/community/members/prakit.24874/
Send a p. m. on here.
Jfets from the store.
Anything on E-bay is likely to be fake!
SP9 has 20dB of Gain
BA-3 has ~30dB of Gain (I think) if built with the parts listed in the BoM. It can be altered to taste.
F4 has no voltage gain
KT88 amp?
Either way - you should not go by the position on the volume knob to determine how loud it will be. The BA-3 in the place of the SP9 will likely "get louder faster" if the gain numbers are correct and if you build it with a potentiometer with the same slope.
Yes
No, they sell the JFETs in the DIYA store. You can buy the Fairchild MOSFETs from most reputable places like Mouser, Digikey, Arrow, or someone more local to you. It is a bit harder to find the original Toshiba MOSFETs, but you don't need them.
Some people like tubes. It's a matter of preference. You can read this if you like for at least one person's impression of the BA-3 as a pre-amp compared to another tube pre-amp.
https://sites.google.com/site/audiosocietyofminnesota/Home/diy-projects/pass-ba-3-preamplifier
BTW - AR is based in MN, so these guys know...
It depends on what PSU you want to use. See this thread for lots of great recommendations. If you have trouble, just write again. There are lots of options.
Electronic parts can be found at Mouser etc. like listed above.
Chassis and other mechanical parts are usually sourced from any number of places. It is your choice.
A transformer for your PSU can also be found at a number of places. Again, ask if you have trouble with what you need or where to get it.
Wire etc. is your choice.
Someone in your country may have wonderful local sources to save on shipping and some costs. As you may know, some parts have become challenging to get at the moment, so you may need to be patient.
Enjoy!
First and foremost thank you all for reading and for taking so much time to reply to a total newbie
Case wise, read that the 10mm front panel might turn into a con since would be hard to drill to fit volume, source and power switch, I got the 10mm black 4U case for the F4 (haven't seen it as my friend who's gonna assemble the power amp got it for me), it would be nice to have similar ones to suit each other, any counter indication on the 10mm vs the 4mm one or any other option besides the Galaxy one?
Grazie again for your help, very much appreciated
Giovanni
What, in your all opinion, would be the best/right gain to drive the F4? If I get it right depending on this parameter components vary, correct?
At this moment in time my power amp is an Aeron AP890, a built in China Italian project around a push pull of KT88 tubes
Ok, I suppose potentiometers are linear and not logarithmic, have never pushed the know past 12h, the L220 produce enough pressure for my taste nonetheless JBL fans advise 3 digit numbers for Wattage, reading the whole thread it seems that the choice is between 25 and 50 K for it, correct?
Since I will likely buy the boards on the DIY store as well as I did for the F4 I'd get whatever it needs besides big stuff which I would buy here in Italy or in the EU such as case (read about the Galaxy 388 which should suit) and transformer.
Case wise, read that the 10mm front panel might turn into a con since would be hard to drill to fit volume, source and power switch, I got the 10mm black 4U case for the F4 (haven't seen it as my friend who's gonna assemble the power amp got it for me), it would be nice to have similar ones to suit each other, any counter indication on the 10mm vs the 4mm one or any other option besides the Galaxy one?
Yep, read that blog, interesting and fun to see how many they built, it gotta sound good enough if so many of them went for it...
I will, grazie!BTW - AR is based in MN, so these guys know...
It depends on what PSU you want to use. See this thread for lots of great recommendations. If you have trouble, just write again. There are lots of options.
Since the preamp is not a priority, at least not until the F4 gets its way home, what do you think, would it be too hard for a beginner to put it all together? I'd better prefer to buy another DMM (digital multi meter, is it how you name it? Mind you, I am Italian so my English is what it is...), I have one which fits regular house duties but it seems it takes two to adjust bias; also I'd buy a better soldering station and than have fun at building it myself with your help but dunno how would I even drill holes to fit knobs, switches, AC, plugs...Electronic parts can be found at Mouser etc. like listed above.
Chassis and other mechanical parts are usually sourced from any number of places. It is your choice.
A transformer for your PSU can also be found at a number of places. Again, ask if you have trouble with what you need or where to get it.
Wire etc. is your choice.
Someone in your country may have wonderful local sources to save on shipping and some costs. As you may know, some parts have become challenging to get at the moment, so you may need to be patient.
Enjoy!
Grazie again for your help, very much appreciated
Giovanni