Wayne's BA 2018 linestage

[Adams_Leo]

anyone can help to what is output impdence of this preamp? Does is lower enough and can driver the Nelson‘s 50w Single-Ended BAF2015 of 2SK77 version？
thanks

 

[wayne]

The output impedance is a fraction of an Ohm and will drive it fine.

 

[Adams_Leo]

thanks wayne quick reply

 

[rookakoma]

I Would like to lower the gain. 2x would be enough
Is it OK, when I change R17 value to 27k?
I would like to keep the R16, because of I don't want to change the C1.
(I don't have other values in my drawers.)

 

[wayne]

I haven’t tested it with a gain that low. It may work and I can try it when later this week.

 

[rookakoma]

Thanks Wayne

 

[wayne]

Looks like it is just fine to make both feedback resistors 27K to lower the gain to 2X.

 

[rookakoma]

That's good. Thank You.

 

[wdecho]

Looks like it is just fine to make both feedback resistors 27K to lower the gain to 2X.

I want to thank you too. Having big horn speakers it benefits me having less gain.

 

[Mod Man]

Received the GlassWare audio bipolar supply today and they did a fantastic kitting job. All parts individually bagged and labeled.
6L6, looking at your post 235 I think you chose the 1 ohm resistor for R3 in the CRC filter. Is was thinking of using the3.3 or maybe the 10 ohm resistor because the total current is something like 60 mA. Any thoughts?

 

[6L6]

Go with what the manual suggests for the current. I didn't build the board in the photos, John sent it to me already built.

 

[Russellc]

Go with what the manual suggests for the current. I didn't build the board in the photos, John sent it to me already built.

Whoops, I just duplicated your pic! What should it be? I really couldnt tell what to do from the instructions...I used the Antek transformer you suggested.

Russellc

 

[6L6]

Test the PSU, if it has proper voltage connect to the circuit and enjoy. It's a great (and very quite) PSU and the minor changes in the book are not going to make any substantive difference.

 

[Russellc]

I'm not even sure what difference the three different resistors are supposed to make. Instructions basically say little more than to use the one you need sort of thing. They are a little more specific on the parts that determine the output voltage.

Russellc

 

[6L6]

Its just passive filtering. The smaller the current draw the bigger the resistor you can use.

 

[damuffin]

I just through together a supply that I had laying around. It’s very compact and sounds pretty nice. It’s based on dual TPS7A3301.

https://www.diyaudio.com/forums/ven...vailable-bal-bal-se-se-lpuhp.html#post3516741

 

[wayne]

Now that is a nice circuit "board". I have more than one of those around.

 

[Russellc]

Received the GlassWare audio bipolar supply today and they did a fantastic kitting job. All parts individually bagged and labeled.
6L6, looking at your post 235 I think you chose the 1 ohm resistor for R3 in the CRC filter. Is was thinking of using the3.3 or maybe the 10 ohm resistor because the total current is something like 60 mA. Any thoughts?

For those that are going this way, it is a really nice kit. I was missing a couple of parts which was frustrating. I emailed that info in but received no reply. Fear not. Within a day or two I got a shipping notice, and next day or so had package with those parts.

Lesson is, he is listening and will send any parts that are missing. This is the 3rd power supply I have ordered from this outfit. Two for a couple of BA3 FE preamp builds, and this one. First one that was missing anything, and it was quickly taken care of!

Russellc

 

[6L6]

Damuffin - Looks fantastic!! Breadboarding a project is a great idea, simple to try, simple to work on if you're needing to tweak it.

PSU - Yours from The Wire is perfect. It's a quiet supply and small, the Burning Opamp is quite tolerant of supplies, I've tried 3 so far all with great results. Find a cool chassis and box it up!



Might want to add a potentiometer...

 

[Russellc]

680ohm

That's also the value supplied in the kits I made.

Hmmm. I have no 680. I do have four pieces of 680K....


Russellc