Still no break-up. 2x 5F1's.

[Sea Chief]

Then your 6V6 should be begging for mercy.

What do you mean? Im just doing tests blind; the measurements mean 0 to me. I hope to learn the significance of them as I go.

[Chuck H]

Then your 6V6 should be begging for mercy.

I thought that was low!?! Considering that we WANT the power tube to clip. It probably has something like 20V of bias. I might have expected something over 50V to be a "correct" amount.

Since I don't have a 5F1 (or any single ended amps to test for a certain result) I can only assume that, for example, a typical PI swing voltage might be 120VAC or more peak to peak, so half that for a single ended amp?!?

Obviously the amp is making some big power for it's design. Maybe that's why it's called a "Champ" That could be why SC is describing these amps as mini Twins. Loud and clean for their size.

Does anyone else think the 30VAC drive voltage on a big whackadoo chord is low for achieving clipping?

[g1]

Does anyone else think the 30VAC drive voltage on a big whackadoo chord is low for achieving clipping?

guitician in post #117 stated he had 30VAC at the power tube grids when he plucked the low E. Unfortunately he did not mention what this gave him as output at the speaker, or whether the 30VAC drive gave clean or distorted sound.
That would be very valuable info.

[Jazz P Bass]

More valuable would be the 6V6 grid voltage at max clean.

And then full bore balls to the wall power.

[Chuck H]

guitician in post #117 stated he had 30VAC at the power tube grids when he plucked the low E. Unfortunately he did not mention what this gave him as output at the speaker, or whether the 30VAC drive gave clean or distorted sound.
That would be very valuable info.

Yep. Threads gettin' long.

Is guitician's reading of a "plucked low E" what he considers a nominal voltage after the attack??? Meaning that the peak for a chord is much higher. And is Sea Chief's reading at "full whackage" (loved that BTW) the highest number to appear on his meter as a peak??? Meaning that his nominal voltage is much lower. All this is way to subjective to interpret with the tests being done as they are. The potential variance is huge. A signal generator would help a lot.

[Sea Chief]

Morning- thanks for the replies overnight.

[yup thread long- that why I thought start a new b'stard].

Anyway my 30 vac reading was the peak figure/ absolute max I read at max whackage (a strum may have been perhaps ~12 vac).

[pdf64]

The Champ schematic with test signal voltages may be helpful http://support.fender.com/schematics...atic_Rev-B.pdf

Also perhaps signal generator software for pc https://www.google.co.uk/search?q=si...m=122&ie=UTF-8 or smartphone https://www.google.co.uk/search?q=si...+generator+app

[Sea Chief]

Hi pdf64-

thanks for those: Im sure schematic will be useful.

I looked up free signal generator s'ware, seems I need a sound card or something- alas Im sure likely way above my humble oldXP pc. Ive never even touched a smartphone let alone used one.

[DrGonz78]

Hi pdf64-

thanks for those: Im sure schematic will be useful.

I looked up free signal generator s'ware, seems I need a sound card or something- alas Im sure likely way above my humble oldXP pc. Ive never even touched a smartphone let alone used one.

Your PC probably has a built in sound card or something where you can listen to music(headphone, line outs, etc.). I really like Audacity since it is free and it has a built in tone generator. Also, you can record guitar tracks and loop play those as a different signal generator.

Audacity: Download

[Sea Chief]

I'll have a go at that now DrGonz78 thanks.. but I bet it'll constipate my 'puter.

[Sea Chief]

DrGonz78-

I seemd to have downloaded something ok.. 'Wavepad Sound Editor Masters Edition' and get a screen with controls and a grey interior.. but I havent a -clue- what it is or anything!

[DrGonz78]

Yeah I am sure wavepad has a tone generator built into that package. NCH software is the company or something, so try this out... NCH Tone Generator - Free download and software reviews - CNET Download.com

[Jazz P Bass]

'Wavepad Sound Editor Masters Edition'
This software is used to 'edit' prerecorded files.
It is not a 'generator'.

[Jazz P Bass]

Anyway my 30 vac reading was the peak figure/ absolute max I read at max whackage (a strum may have been perhaps ~12 vac).

That 30Vac grid figure will most probably distort.

For sure, the strumming 12Vac will not.
There is simply not enough drive signal to slam the output tube into distortion.

Seeing that this is NOT a Fender issued product & simply a cobbled together creation, I truly believe that you are tilting with windmills.

Play the thing, add a boost pedal & call it day.

[Dave H]

I thought that was low!?! Considering that we WANT the power tube to clip. It probably has something like 20V of bias. I might have expected something over 50V to be a "correct" amount.

Since I don't have a 5F1 (or any single ended amps to test for a certain result) I can only assume that, for example, a typical PI swing voltage might be 120VAC or more peak to peak, so half that for a single ended amp?!?

Obviously the amp is making some big power for it's design. Maybe that's why it's called a "Champ" That could be why SC is describing these amps as mini Twins. Loud and clean for their size.

Does anyone else think the 30VAC drive voltage on a big whackadoo chord is low for achieving clipping?

If the bias voltage is 20V then it's going to start clipping at 20V peak or 14V rms (for a sine wave) so I thought 30V (rms) would be enough to get a good bit of distortion. The top half of the waveform will be clamped to 20V peak by the 6V6 grid so you can't really measure the full drive signal available without disconnecting the grid. The meter reads average voltage not peak. You really need a scope to see what's going on. The meter is only calibrated rms for a sinewave but we don't have a sinewave. It's going to look like a sinewave for the negative peaks but clamped square at 20V for the positive peaks and the meter will take the average of that.

The 5F1 circuit I have shows both 12AX7 cathode resistors unbypassed and it has output stage negative feedback. I'd disconnect the feedback and bypass both cathode resistors with caps. That would make it overdrive for sure.