Shot in the dark Ecstacy filtering?

[joesatch]

Schematics are floating around and i'm working from this one for preamp build. The clean channel runs off V1-V2 while the dirty channels run off V3-V4.  I would assume that the V1-V2 B+ is higher than V3-V4?   I have the voltages i found online for the dirty channels  Anyone know the B+ for V1?

[HotBluePlates]

... The clean channel runs off V1-V2 while the dirty channels run off V3-V4.  I would assume that the V1-V2 B+ is higher than V3-V4? ...

The voltage doesn't really matter.

The Clean channel will always be cleaner than the Dirty channel, because there is a lot of signal reduction in the interstage attenuators and further signal reduction in the plate-driven tone stack.

The Dirty channel has (at least) 3 gain stages, but less interstage signal reduction and uses a cathode-follower-driven tone stack at the end of the preamp.  Even if voltages are identical (or lower), the Dirty channel will have higher output & be more distorted.

[joesatch]

well i guess my B+4 and B+5 nodes will be the same voltage. well see how this goes. not used to supplying a clean channel circuit with such a low B+  (240vdc in this case)

[TIMBO]

Lots of info here
Upstairs, Downstairs Chassis????? (el34world.com)
Voltages on reply #40

[joesatch]

thanks but reply #40 has a file in it that i cannot read. what type of file is it?

[sluckey]

thanks but reply #40 has a file in it that i cannot read. what type of file is it?

Read this...

     https://el34world.com/Forum/index.php?topic=590.msg1622#msg1622

[joesatch]

thanks i was trying to open it with diy layout creator. The file has a schematic and the last tab it has a voltage chart.  The "F" in the schematic says 240vdc but in the chart it says 342vdc.  I'm very confused here

[TIMBO]

Hey mate, Was a long time ago I built that.
I think the "240v" was a reference from the schematic that I copied mine from
I wouldn't worry too much about what the node voltage are or could have been.
I have built this circuit several times and have trimmed it down to just the blue channel.
It's an amazing amp and no matter what.....

[joesatch]

hey thanks . there is a massive difference between 342vdc and 240vdc on the F node. which should i go with?

[TIMBO]

Here is another I did
Marshall VS100 Repurpose (el34world.com)
Yes I agree can't say it why is.

[HotBluePlates]

... there is a massive difference between 342vdc and 240vdc on the F node. which should i go with?

Repeat after me:  "It doesn't matter that much."

Timbo's first example showed 340+ volts for the preamp supply, and his second example showed 300v for the preamp supply.  The voltage difference isn't that important, as long as the decoupling resistors between the filter caps are reasonably-sized (which is the case for the schematics of both Timbo's examples).

[PRR]

....as long as the decoding resistors ....

"Decoupling"?

Back in the day, we never thought internal voltages were critical. Certainly not in middle stages; yes in the power stage low voltage explained low power and we'd work on that.

Anyway it is SUPER easy to fiddle the dropping/decoupling resistors after the smoke-test. Even Fender did not always get the "optimum" first try, even when production pressures pushed a product to showrooms when only 98% done. It plays, it ships!

[HotBluePlates]

....as long as the decoding resistors ....

"Decoupling"?

Macs have this nasty habit of some little bit of something working its way under the keys until some letter doesn't want to register when pressed.

Oddly, in quite a few Macs (including mine) that happens on the "P" key.

So when I type "decouling" with the missing "P" it tries being helpful and auto-spell-corrects that to "decoding" (though for some reason it knows it should be "decoupling" until the "G" is typed).

And after all those words, I'm not gonna proofread... 

[joesatch]

preamp B+ voltages definitely matter. try building a SLO circuit with low B+ and get back to me

[TIMBO]

Hey mate, I do agree that voltages play a big part in certain amps.
BUT, with a gazillion schematic out there all claiming to be correct down to the last volt and resistor value......
Which one is IT????
10W SLO CLONE (el34world.com)
This is one I built
Bits and pieces, odd transformers, VVR......
Sounds F####N Awesome
Voltages were what they were and God knows I don't know what they are suppose be
Trying to get an exact copy of the original will do your head in.
I'm a trial and error guy and have NO tech training.
If they sound close to what I can find on the net, good enough for me.


So what does a SLO sound like with low B+.....