I used Forstner bit for drilling without any trouble for the 10mm faceplate as it is soft. Use cooling fluid to make a clean cut with the drill set to low speed. For the 4mm panel, even a spade will do for bigger holes and regular drill bit for smaller holes.
Also, if you want ~30dB of gain, make sure your power supply have enough voltage swing( mine is set to +- 30Vdc).
F4 and the BA-3 FE is a great combo IMO. I have the combo and it was responsible for me not to build the case of my BA-3FE for the longest time as I was scared to touch it for fear of losing the magic. But in the end, a plywood test case will not cut it for me. Enjoy your build!!
Awesome - what did you use to power the Muses?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!
View attachment 1008450 View attachment 1008451
Hi,
I am using a VRDN (https://www.diyaudio.com/community/...l-ckts-11v-to-20v-1-5a-with-de-noiser.355883/) from Mr. Mark Johnson as can be seen in post# 2364 with the cardboard
. I tried other supplies like bipolar transformer base(from BlockUSA), DC/DC converters from CUI, and a version of Son of Zen bipolar supply (LM317) and it's good. I know that the VRDN is an overkill but I already have it and to me, it made a difference in sound to the Muses (besides the one installed in the preamp, I have two others as backup, one with an OLED display). My impression is that an ALPS volume pot or similar (PEC and Goldpoint is what I compared to it) cannot touch the sound of the MUSES especially its clarity and presentation.
Looks great. I cheated and bought an assembled LT3045/3094 supply from eBay.Hi,
I am using a VRDN (https://www.diyaudio.com/community/...l-ckts-11v-to-20v-1-5a-with-de-noiser.355883/) from Mr. Mark Johnson as can be seen in post# 2364 with the cardboard
View attachment 1009186
I know that the VRDN is an overkill but I already have it and to me, it made a difference in sound to the Muses (besides the one installed in the preamp, I have two others as backup, one with an OLED display). My impression is that an ALPS volume pot or similar (PEC and Goldpoint is what I compared to it) cannot touch the sound of the MUSES especially its clarity and presentation.
View attachment 1009187
Finished my BA-3 preamp a month ago.
Yeah!
Sounds great.
I want to thank everyone and the forum for the assistance along the way.
Biased to 1DCV.
Using it with my F6, M2X and F4.
The one question I have is that the F4 needs the volume to be at the 3:00 position on the volume pot, vs. 12 for the F6 and M2X.
I rechecked the F4 and it's spot on for bias at .2DCV each channel.
I get the same result with my Akitika preamp PR -102.
I'm driving Magnepan 1.71 speakers, so 4ohm, but 6L6 has said: "F4 can send a lot of current to a speaker and Magnepans will be driven with poise, control, style and grace." [F4 build guide forum #2503]
Just wondering if I missed something somewhere?
Yeah!
Sounds great.
I want to thank everyone and the forum for the assistance along the way.
Biased to 1DCV.
Using it with my F6, M2X and F4.
The one question I have is that the F4 needs the volume to be at the 3:00 position on the volume pot, vs. 12 for the F6 and M2X.
I rechecked the F4 and it's spot on for bias at .2DCV each channel.
I get the same result with my Akitika preamp PR -102.
I'm driving Magnepan 1.71 speakers, so 4ohm, but 6L6 has said: "F4 can send a lot of current to a speaker and Magnepans will be driven with poise, control, style and grace." [F4 build guide forum #2503]
Just wondering if I missed something somewhere?
Attachments
I've been following this thread for quite some time and after finishing a loudspeaker build I intend to kick off my BA-3 construction. I have all the parts and enclosure ready to go. A question I have that has not been put forth that I am aware (I apologize if I missed it) is can the BA-3 support dual single ended outputs. I need to drive both the main amp as well as the subwoofer amp? I will do this until I can complete the 6-24 electronic crossover, which based on my track record could be a bit of time. Thanks for your help.
As ZM says, you want 50Vpp voltage swing, and 10x (20db gain) if you absolutely must have every bit of power the F4 is capable of. I suspect in many cases, people don't need as much power as they really think they do...
Just in case you didn’t already know, you can adjust the gain-structure by fiddling with R13 (on the FE). Copied from post #2027:
»I also built stock BA-3 Front end (R13 = 330R) with non Toshiba parts and get a gain of 10 times or 20 db.
In Papas article he gets 30 db:
"The voltage appearing at the Gate of Q3 is amplified by something less than the ratio of R10 divided by R8, and with the same happening at Q4 and considering the transconductance of the Mosfets, comes out at about 15. Both of them added make a system voltage gain of about 30X, or 30 dB." «
You‘ll find plenty of this in this thread, some of it around #2020 ff
»I also built stock BA-3 Front end (R13 = 330R) with non Toshiba parts and get a gain of 10 times or 20 db.
In Papas article he gets 30 db:
"The voltage appearing at the Gate of Q3 is amplified by something less than the ratio of R10 divided by R8, and with the same happening at Q4 and considering the transconductance of the Mosfets, comes out at about 15. Both of them added make a system voltage gain of about 30X, or 30 dB." «
You‘ll find plenty of this in this thread, some of it around #2020 ff
Hello everybody.
I have a doubt, I set up an F4 and a Ba3 preamp., Make an extraordinary set.
My problem is that after a few months, i detected an unbalance between channels and the sound is less transparent. In 3 years it has happened several times.
When this happens I verified BA3 Bias and it is with a lower value + - 0.85V., the power supply maintains the 24V.
Adjusting the Bias and transparency returns.
Does this happen to all or mine has a problem?
Thanks.
P. Dias
Portugal
I have a doubt, I set up an F4 and a Ba3 preamp., Make an extraordinary set.
My problem is that after a few months, i detected an unbalance between channels and the sound is less transparent. In 3 years it has happened several times.
When this happens I verified BA3 Bias and it is with a lower value + - 0.85V., the power supply maintains the 24V.
Adjusting the Bias and transparency returns.
Does this happen to all or mine has a problem?
Thanks.
P. Dias
Portugal