Dynaco SCA-35 project "Start-Me-Up" with EFBâ„¢

[DerekVa]

But isn't that the Audio Regenesis board already?
http://audioregenesis.com

I would make the board the same dims as the Rev C & Rev D, so a retrofit would be easy.

I'm in the bowels of a commercial Budgie project. It basically has absorbed all my tube time in the last several months. But the revamped ST35 is on my short list of 2012 projects.

Shannon

No - the Audio Regenesis board is (sadly) both a PS board and EFB board and specifically, the PS portion is for the SCA-35, which is notably different from the ST35 PS. While it is a great product, it outputs the wrong voltages for the driver/phase inverter since the SCA-35 is designed around the 7199 instead of 7247 (or in the case of the DIYTube ST35, a 12AX7 and 12AU7). You'd have to cut traces since it comes fully assembled from Audio Regenesis.

And while a new board with the same dimensions would be great, it would be a PITA to retrofit as you'd have to remove all the parts from the existing board (or buy a new BOM to stuff the new board) and solder them onto the new board. If there were simply a separate EFB board (not even a PSU + EFB, but just a mini EFB board), then it would be relatively trivial to add to an existing ST35 (DIYTube or old Dynaco).

Just my $0.02. Thanks!

-D

p.s. And what on earth were you doing online at 4:36AM? Did the baby get you up?

[corndog71]

If you stick with the ST35 chassis then the audioregenesis board obviously won't fit. You should be able to mount the EFB parts to a small bread board and hide it inside the ST35 as they don't take up much room.

Here they are on my PS board:


The audioregenesis PS board WILL work for the DIYtube circuit. Both DIYtube and stock ST35 circuits require 360V from the high voltage portion. I modeled my PS on it and it sounds fantastic. The one main difference is that the AR board has an extra RC stage for the preamp board of the SCA35.

[DerekVa]

If you stick with the ST35 chassis then the audioregenesis board obviously won't fit. You should be able to mount the EFB parts to a small bread board and hide it inside the ST35 as they don't take up much room.

Here they are on my PS board:


The audioregenesis PS board WILL work for the DIYtube circuit. Both DIYtube and stock ST35 circuits require 360V from the high voltage portion. I modeled my PS on it and it sounds fantastic. The one main difference is that the AR board has an extra RC stage for the preamp board of the SCA35.

I stand corrected on the voltage - it looks like in both cases, it's 320V at the point at which it goes to the driver / phase splitter. My mistake in reading the manuals (the voltage points aren't marked well in the old manuals).

-D

[DerekVa]

FWIW, like many on this forum, my ST35 circuit is NOT in an original Dynaco chassis, so I have lots of room to work with. I just prefer the cleanliness of a well-designed circuit board. Unfortunately, you get PS + EFB with the SCA-35 kit, and I only am looking for EFB.

-D

[DerekVa]

...now if there were only Diytube ST-35 EFB boards available.....!

Hopefully very soon. I had hoped to have some prototypes done by Christmas, but another project has zapped my time. Working with Dave and plan to have it be exactly the same footprint as the Rev C and Rev D (for easy swaps). Rev EFB?

Shannon

One additional question - any chance the EFB portion will be multiple-configuration (e.g. quad / channel / single biasing)? If it is configured to use small through-hole trimmers like the Bourns 3362W-1-502LF, the builder can decide how they want to handle the hassle of biasing versus the hassle of trying to find matched quads of EL84 and stuff and/or jumper the EFB section appropriately. If it is, I might just be one of the first people to spring for a new Rev.EFB board.

Sorry for being a demanding PITA.

-D

[Shannon Parks]

One additional question - any chance the EFB portion will be multiple-configuration (e.g. quad / channel / single biasing)? If it is configured to use small through-hole trimmers like the Bourns 3362W-1-502LF, the builder can decide how they want to handle the hassle of biasing versus the hassle of trying to find matched quads of EL84 and stuff and/or jumper the EFB section appropriately. If it is, I might just be one of the first people to spring for a new Rev.EFB board.

This is TBD. Any mods I do I would want Dave's blessing on, so we'll see.

Oh yes - 4:30am to 6:30am is my diytube work schedule: my few hours of solitude.

Shannon

[DerekVa]

One additional question - any chance the EFB portion will be multiple-configuration (e.g. quad / channel / single biasing)? If it is configured to use small through-hole trimmers like the Bourns 3362W-1-502LF, the builder can decide how they want to handle the hassle of biasing versus the hassle of trying to find matched quads of EL84 and stuff and/or jumper the EFB section appropriately. If it is, I might just be one of the first people to spring for a new Rev.EFB board.

This is TBD. Any mods I do I would want Dave's blessing on, so we'll see.

Oh yes - 4:30am to 6:30am is my diytube work schedule: my few hours of solitude.

Shannon

I don't miss having an infant in the house. Now, of course, it's trying to get the kids out of bed so they're not late for school.

-D

[EWBrown]

Having the Rev E / EFB board would be great! I already have a "ready to go" chassis, which housed a Rev D board at one time, and it still has all of the transformers, RCA's, AC power input circuitry, , speaker binding posts, etc installed. The REv D board was relocated into a "Triode" ST35 chassis, along witn a pair of teh nice MQ 565 OPTs,

So that would be an easy and quick new ST35 project for me, as all of the "scut work" is already done

Or maybe, the D board will go back into its original chassis, and the REv EFB will be installed into the Triode chassis, wither way, it would be a nice combination

/ed B

[DerekVa]

Having the Rev E / EFB board would be great! I already have a "ready to go" chassis, which housed a Rev D board at one time, and it still has all of the transformers, RCA's, AC power input circuitry, , speaker binding posts, etc installed. The REv D board was relocated into a "Triode" ST35 chassis, along witn a pair of teh nice MQ 565 OPTs,

So that would be an easy and quick new ST35 project for me, as all of the "scut work" is already done

Or maybe, the D board will go back into its original chassis, and the REv EFB will be installed into the Triode chassis, wither way, it would be a nice combination

/ed B

Ahem...line forms to the left, Ed.

-D