Ugly distortion with tube amp when you play

[Ampzone]

That looks OK for idle; what about when you apply signal and turn up the volume - how large is the current fluctuation?
I use a bias probe to get a feel for what is going on ....
Also, can you swap out the OT for a known good one, just to rule out the OT

so on V8 it idle's at 31ma, when you play with volume at 50% it spikes at 50-60ma on the tube. Keep in mind the sound is very choked off. low output with distortion

[Ampzone]

100hz tone.
Starting first pic is the input jack 1meg & 68k intersection, next input jack 68k&68k intersection, next 68k and input volume pot, v2 pin 6, 220pf cap. Not sure if this helps at all.

and treble pot and 220pf cap intersection.

[nickb]

Your input signal is too big - you need reduce it to around 100mV. It's around 2-3V peak right now. The input vol pot shot shows you close to a square wave indicating V1 is being driving to clipping.

This may be a side issue but it's looks like a 45Vpp swing max at that point. I would have expected more. Check the DC at all V1 pins and on it's supply (22K/16uf junction).

[Ampzone]

Your input signal is too big - you need reduce it to around 100mV. It's around 2-3V peak right now. The input vol pot shot shows you close to a square wave indicating V1 is being driving to clipping.

This may be a side issue but it's looks like a 45Vpp swing max at that point. I would have expected more. Check the DC at all V1 pins and on it's supply (22K/16uf junction).

voltage on the supply cap are appx 320 & 260v DC. I will do another scope pass directly.

[nickb]

voltage on the supply cap are appx 320 & 260v DC. I will do another scope pass directly.

..and what about DC on the V1 pins (plate x2, cathode x2 , grid x2), as requested? Make a table of pins # vs voltage.

[J M Fahey]

Your signal is too loud and to boot, not very significative for a guitar amp.

Download 1kHz tone here Download Audio Tone Files and play it through any MP3player or equivalent.

Not sure about a phone because some "try to protect you" and tame output volume a lot when you use the headphones out, at least my LG does, I hate it.
Any standard cheap player will give you 100 to 200mV RMS out of the headphone out.
That site also has other interesting frequencies, download them all for future tests.

[Ampzone]

Your signal is too loud and to boot, not very significative for a guitar amp.

Download 1kHz tone here Download Audio Tone Files and play it through any MP3player or equivalent.

Not sure about a phone because some "try to protect you" and tame output volume a lot when you use the headphones out, at least my LG does, I hate it.
Any standard cheap player will give you 100 to 200mV RMS out of the headphone out.
That site also has other interesting frequencies, download them all for future tests.

Here is the 100mv output level 100hz tone. I can do another pass with 1k.

Fist pics V1 input, 2nd 220pf cap, 220pf and treble pot leg and last Master Vol pot leg running to V3 and a shot of the setting on the scope

[Ampzone]

votlages v1 leaving out the heaters and such

1= 242
2=110v
3=112
6=110
7=0
8=0.1v

V2
6=142
7=0
8=1.2v

v3
1=300v
2=70
3=74v
6=202
7=0
8=1.2v

V4
1=305
2=74
3=78
6=309
7=67
8=78

[Ampzone]

someone mentioned dropping in another output tranny to rule this out, I have a marshall type 50w on hand that I can clip in or are resistance test enough? Between the primary's they are under 20ohms which looks right to me.

[TigerAmps]

Leave the Marshall transformer outside the chassis (extend the wires if necessary).
I would wire in the the primary (3 wires) on the tube sockets, removing the current OT connections (tape them off to insulate them).
On the secondary, I would use only 2 wires ground and one of the taps (tape the others off to insulate them).
I would wire the 2 secondary wires to a 1/4 inch jack or directly to a speaker.
Also, remove 2 of the 4 (if using 4 ) output tubes and check the bias.
This way you are going directly from the plates of the output tubes to the transformer then directly to the speaker.
I would also start with the feedback wire removed if one exists (taped off as well).
If the distortion still exists, it is before the output tubes.
If it does not exist, it is most likely with the OT or connections/wiring of the OT.

[g1]

Your V1 voltages are bad. So there is a problem there. But your V2 voltages show that the preamp schematic you linked is not right for this version. The layout and your voltages indicate only 1/2 of V2 is being used.

Edit: This preamp should better match the layout:

[Jazz P Bass]

Whoo hoo.
110 volts on V1's grid.

[Ampzone]

Leave the Marshall transformer outside the chassis (extend the wires if necessary).
I would wire in the the primary (3 wires) on the tube sockets, removing the current OT connections (tape them off to insulate them).
On the secondary, I would use only 2 wires ground and one of the taps (tape the others off to insulate them).
I would wire the 2 secondary wires to a 1/4 inch jack or directly to a speaker.
Also, remove 2 of the 4 (if using 4 ) output tubes and check the bias.
This way you are going directly from the plates of the output tubes to the transformer then directly to the speaker.
I would also start with the feedback wire removed if one exists (taped off as well).
If the distortion still exists, it is before the output tubes.
If it does not exist, it is most likely with the OT or connections/wiring of the OT.

Ok good, I will try this next. Stay tuned and thank you

[Ampzone]

Your V1 voltages are bad. So there is a problem there. But your V2 voltages show that the preamp schematic you linked is not right for this version. The layout and your voltages indicate only 1/2 of V2 is being used.

Edit: This preamp should better match the layout:
[ATTACH=CONFIG]34009[/ATTACH]

Thank you, I was trying to find the closest layout as the person I got this from had no layout and said it was a ceritone (spelling) kit, it must have changed or was modified a good deal as noted by G1 as it does not match the layout I found.

I will look around V1 and see what gives on the grid.

[Jazz P Bass]

It is not simply the grid voltage of V1 that is off.
The cathode is way high (because of the grid?)

If the amp matches G1's layout, a mulimeter resistance check should suss it out.

Each plate has a resistor (220K) to the preamp B+.
Each cathode has a resistor (2.2K) to ground.