I used the same dimensions as I found on the thread for MK2, made in 2019 and used the closest US measurement values. It won't be the same size or functionality as the first versions...
they are: AMP PCB is 5.00'' x 4.00'', PSU PCB is 4.00'' x 4.00''
Will post more detailed measurements later.
they are: AMP PCB is 5.00'' x 4.00'', PSU PCB is 4.00'' x 4.00''
Will post more detailed measurements later.
I would like to ask to BHEL34 users how they have set the gnfb and the shunt feedback: what values do you use for R13, R1 and R2?
Has anyone installed a potentiometer instead of R1, to give less gnfb at low volumes & simpler music stiles, then more gnfb with higher volumes and more complex music?
This is what I usually do in my guitar amps and what I was thinking to install on my hi-fi after last tests I did:
improvements on 12AX7 12AT7 EL34 schematic?
and after reading this:
https://www.hificritic.com/uploads/2/8/8/0/28808909/classic-sc3-future_without_feedback.pdf
Has anyone installed a potentiometer instead of R1, to give less gnfb at low volumes & simpler music stiles, then more gnfb with higher volumes and more complex music?
This is what I usually do in my guitar amps and what I was thinking to install on my hi-fi after last tests I did:
improvements on 12AX7 12AT7 EL34 schematic?
and after reading this:
https://www.hificritic.com/uploads/2/8/8/0/28808909/classic-sc3-future_without_feedback.pdf
Another BH
Just finished my 2nd Baby Huey.
This one uses the MK2 boards and MK2 psu I purchased last year.
It also has all the latest tweaks that Ian (gingertube) has suggested over time. I didn't get too concerned about aesthetics on this one. I sort of like that minimalist look
These are such great amps, thanks to all who had in put on this great project!
gabo
Just finished my 2nd Baby Huey.
This one uses the MK2 boards and MK2 psu I purchased last year.
It also has all the latest tweaks that Ian (gingertube) has suggested over time. I didn't get too concerned about aesthetics on this one. I sort of like that minimalist look
These are such great amps, thanks to all who had in put on this great project!
gabo
Attachments
Hi gabo,
Congratulations! Well done!
Thanks Francois. I see you've been helping a lot. There seems to be a new generation getting into the BH! They will not be disappointed.
gabo
Greetings, my friend!
Very nice second build! I wonder why this second, but let that rest for now.
I just try to helps fellow-builders with information I gathered from folks like you.
I wondered about your unique chassis construction, which I found very worthwhile contemplating. What is the gauge of the top/side panels (looked like an 1/8th inch of aluminum). I really like the side panels of nice wood.
How did you bend it in your required shape?
Very nice second build! I wonder why this second, but let that rest for now.
I just try to helps fellow-builders with information I gathered from folks like you.
I wondered about your unique chassis construction, which I found very worthwhile contemplating. What is the gauge of the top/side panels (looked like an 1/8th inch of aluminum). I really like the side panels of nice wood.
How did you bend it in your required shape?
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When I purchased my transformers, I ordered two and I did the same with most components. So I pretty much had all the parts, might as well use them.
The chassis is something I do for many builds. Yes it's 1/8" aluminum. You can purchase off ebay or from metalsdepot.com in large pieces.
All you do is cut a piece the size of the top and front/back. For example, if you want an amp 18" wide x 16" deep x 4" tall, you cut your piece 18x24. Then you bend each end at the 4" mark.
To bend aluminum, you can cut a very shallow cut down a line where you want to bend. I use a router set to just cut about 1/16" of an inch deep. That provides relief and makes it easy to bend. The cut goes on the inside of the bend. Then just use a vice or just "muscle power" to bend it, with a square to know when it's straight.
Then put wood sides on it and you have a chassis. If you want to put a bottom it, just cut another piece of aluminum. Depending on where I'm going to put it, I may just leave the bottom open.
gabo
The chassis is something I do for many builds. Yes it's 1/8" aluminum. You can purchase off ebay or from metalsdepot.com in large pieces.
All you do is cut a piece the size of the top and front/back. For example, if you want an amp 18" wide x 16" deep x 4" tall, you cut your piece 18x24. Then you bend each end at the 4" mark.
To bend aluminum, you can cut a very shallow cut down a line where you want to bend. I use a router set to just cut about 1/16" of an inch deep. That provides relief and makes it easy to bend. The cut goes on the inside of the bend. Then just use a vice or just "muscle power" to bend it, with a square to know when it's straight.
Then put wood sides on it and you have a chassis. If you want to put a bottom it, just cut another piece of aluminum. Depending on where I'm going to put it, I may just leave the bottom open.
gabo
Just use a v-groove bit and a small hand held router.
https://www.amazon.com/Whiteside-Ro...4&sr=1-2-22d05c05-1231-4126-b7c4-3e7a9c0027d0
Thank you for your feedback Ian! KT77 is indeed much more linear around the 25W dissipation curve, applying 43% UL, and this permits to use very low amount of shunt feedback to linearize it, so less stress on the PI. EL34 is way less linear around its maximum dissipation curve with UL only, that's the reason why (I think) it is needed to have more shunt local feedback.
In my current design (hybrid cascoded PI with CCS loaded tube driver) I have R13 at 39k plus some local feedback at sources of the nJFET and a small amount of gnfb to remove some harshness around "S" in certain recordings. But still chasing another configuration to remove gnfb, or at least made it variable as I do in my guitar amps.
Ian, have you done some tests with different UL taps and different shunt feedback?
Thanks!
