The Amp Garage

I just finished the initial build of a single channel deluxe reverb, sans tremolo. I'm using a classictone 40-18019 PT and the OT from a Hammond AO35. The hammond has 2 EL84's into an 8r load. I figured the 6V6 would be relatively close. ... There seems to be some confusion as to whether you've use...

Same as an HT winding where the CT is grounded, the voltages at the opposite ends of the coil are out of phase. The one that is out of phase with the secondary shows a higher voltage because its sine wave is high when the one at the secondary hot is low. Ahh, the voltmeters are with respect to the ...

martin manning wrote: ↑Mon Mar 18, 2024 8:51 pm Like this:

My thinking is both voltages should be the same, any idea what the mechanism is that causes them to differ like that?

M3thoms wrote: ↑Wed Apr 03, 2024 6:28 pm Here's the last version, pretty sure I've got this right guys but as always input is always welcome!

A grid requires a DC path back to its cathode, never leave it floating.

Derek at Watford Valves advises that the Philips ECG WGB run fine in pretty much any guitar amp, even the crazy high voltage late 70s Fenders.
And a mere £50 each!
He better puts his prices up before they migrate back across the pond
https://watfordvalves.com/product_detail.asp?id=1313

... The PT centertap wire to the negative of the first filter cap has big and pulsed (containing higher harmonics) currents running on it. Run that one short and direct, and don't cluster it up with anything else. ... Just to confirm and clarify, the CT of the high voltage winding should be directl...

... On any blackpanel amp if you turn all the tone pots to 0 ... Fender knobs for these amps are 1-10, no 0 available, CCW = 1, CW = 10. ... 6k8 resistance to ground, like a 10kA mid pot set at ~3:00. With a regular 1-10 knob and 10k log pot, I recall a fairly high setting is required, maybe around...

(1) And the heater center taps are sometimes not too accurate. A couple of resistors may well make a better center tap, with lower induced hum. Why do you think that the minimum hum is on the middle of very- too much precision- resistors ? Give us some technical reference and measurement. 8) I've n...

You should start with the bias voltage at the most negative setting (largest number). Talking about negative voltage is always confusing. The convention I follow is more negative is lower, which is mathematically correct and follows the convention for temperature. I still write it two ways to make ...

Yes, all the silverface 70 and 135 watt amps where Ul and as such not what you want it your looking for a true Deluxe playing feel and response . To describe those OTs / output stages as UL implies that their design has been optimised for linearity. As the taps are at about 12.5%, my understanding ...

chaccmgr wrote: ↑Thu Mar 21, 2024 1:35 pm ...
almost everybody uses 18mm/1/2" plywood today, if reinforced, you might get away with 15mm
...

Just to note that rather than 1/2", I think the imperial equivalent of 18mm is 3/4"

Reeltarded wrote: ↑Thu Mar 21, 2024 2:11 am Isn't this a late silver model with UL taps on output?

Not from those transformer codes, they match this earlier version https://el34world.com/charts/Schematics ... man_10.pdf
Still super high HT voltage though.
I seem to recall that the OT there is surprisingly wimpy.

The transformer was designed to cope with 6.3x3= 18.9VA load on that winding. There might be another 150VA load from the HT winding? The total max load might be 170VA. You're wondering whether it'll cope with increasing the heater winding load to 6.3x4.2=26.5VA. The total max load might then be up n...

https://makeabilitylab.github.io/physcomp/electronics/assets/images/Potentiometers_TwoExamplesWithSchematicSymbol.png My understanding is that a regular volume control would wire lug 1 to common, 3 to signal in, 2 to signal out. Schematics usually arrange things so that as the wiper is moved up, th...

It depends how closely you want your build to comply with the design of a Deluxe Reverb. On the face of it, neither transformer aligns with the DR spec. Why have you chosen a DR, rather than eg a Super Reverb 70 https://el34world.com/charts/Schematics/files/Fender/Fender_cbs_70w_mstrvol_pullsw_super...