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

[big_teee]

If you're wired like the weber schematic, are you using input 1 or 2?
https://taweber.powweb.com/store/5f1_schem.jpg
Input 1 is high, and input 2 is the low.

[Chuck H]

No that was already on. The addition was in the middle of the board, I think Chuck H recommended it/ circled it on a thumbnail of my pic as few posts back.

Will it all blow up?

No, it won't blow up. I knew (or believed) that you removed the 22k negative feedback resistor (that's the little red/brown bodied one near where you added the cap). But even if you didn't, adding a large-ish cap across that resistor I indicated raised the gain of that stage by about 3.5dB (a gain increase from about 40 to 60!!!). The difference should be obvious. Very obvious.

[Sea Chief]

If you're wired like the weber schematic, are you using input 1 or 2?
https://taweber.powweb.com/store/5f1_schem.jpg
Input 1 is high, and input 2 is the low.

Yup got that- 2 inputs it has (so like the weber, but with tube rec).

[Sea Chief]

No, it won't blow up. I knew (or believed) that you removed the 22k negative feedback resistor (that's the little red/brown bodied one near where you added the cap). But even if you didn't, adding a large-ish cap across that resistor I indicated raised the gain of that stage by about 3.5dB (a gain increase from about 40 to 60!!!). The difference should be obvious. Very obvious.

I did lift the 22k neg fdbk leg. Then added a 22/25 cap across the resistor thats in series to the 22k next to it (physically above it on the board pic). That right? I assumed the higher capacitance you said (2.2 to 22uf) would yield more growl. I'll be able to hear the amp up full/ give it a whirl to test its growl tmrw.

[J M Fahey]

I just stumped into this incredible 7 page thread ... about a .... Champ !!!!

Won't even read it because I see you are still at square 1, so, why bother?

My first question is, did you build this? (YES/NO):



I much prefer we use a .gif which can be seen real time in the same page, and which can be edited/annotated, instead of a .pdf

[Dave H]

Yes, that's the circuit. We have 10 times as many posts as it has components

[Jazz P Bass]

There has been progress, though.

As suggested in Post #3 & reasserted in Post #184 (thankyou Tom) the 22K feedback resistor was removed with the result being 'distortion'.
(and hum)

Now the issue (it seems) is to try and bring down the way high B+.
(not too sure why)

[J M Fahey]

Thanks guys for answering but the one that matters is Sea Chief's

Just yes or no

[Sea Chief]

There has been progress, though.

As suggested in Post #3 & reasserted in Post #184 (thankyou Tom) the 22K feedback resistor was removed with the result being 'distortion'.
(and hum)

Now the issue (it seems) is to try and bring down the way high B+.
(not too sure why)

Your not sure why s'one wants to bring down the B+.. thats 90v too high? seriously Jazzp?

[Sea Chief]

Yes, that's the circuit. We have 10 times as many posts as it has components

Well, it is, but for the added V1 cathode bypass cap I have which the above schematic doesn't (as mentioned a good few times & easily visible on the close-up photos, added a few times now too).

Dave H- I changed the fatso to a 1K and the B+ now 335v. Im not going to get closer to 340v than that! Surprising that the 470 dropped the whopping 392v by only 14v, but a 1k drops it by nr 60v.. interesting.

Ok as there seems to be silly comments now & the usual unsavoury forum nonsense (mild bullying IMO esp when its many against one) juvenile comments at/ lets laugh at him etc, I think I'll bow out before it gets unpleasant & 'the pack' grows. I'll ignore & won't trust the opinion of these folks from now on simple as that.

To all those who helped (without stupid comments) I really appreciate your patience, & your opinions. It may only start to growl at 7 even with an SG + the mods done (which still confounds me when I hear of Champs breaking up at 4!) Im thru trying to understand why now/ Im not going to find out why. Nevertheless it growls, & as a bonus the excessive voltage is much better too.. so ~job done with your help! Great many thanks.

End of.

Thanks, Sea Chief.

[Chuck H]

SC,

Did you ever recognize an increase in clipping for adding the capacitor I suggested?

It would be interesting (to me at least) if you would measure the voltage across the 1k resistor at idle, and again at full clip. Can you post those figures please.

[Dave H]

It would be interesting (to me at least) if you would measure the voltage across the 1k resistor at idle, and again at full clip. Can you post those figures please.

I tried it in LTSpice. I only have a Champ schematic with a DC power supply but the PSU current was 50mA at no signal and 45mA at full clip (inverse sag) because the waveform was asymmetric.

[Chuck H]

Thanks Dave. That's why I thought it would be interesting. I figured a simulation would demonstrate the inverse sag expected from a class A circuit. I was interested in the real world results though. It looks like SC may have checked out due to thin skin though.