Identifying Power Transformer leads for FENDER Amp

[czech-one-2]

Here :

[ATTACH=CONFIG]39479[/ATTACH]

The two diodes are gone. The red/yellow wire that used to go to the green spot is gone. This is all there is to it.

Remember : if you don't swap those caps for 500 VDC caps or higher they'll blow up.

So, I would add jumpers where the 2 diodes were?

[g1]

No. There are no jumpers shown in that picture. Wire it up just as shown.

[czech-one-2]

Got it, PT/OT is in, waiting on a 680ohm 10w from China....
Any noise reduction benefit from twisting any of those wires together from the bridge rectifier or wire routing suggestions?

[czech-one-2]

No. There are no jumpers shown in that picture. Wire it up just as shown.

Instead of joining the AC input bridge rectifier wires and the 350v PT wires at the at the eyelet board, can I just wire the 350v PT wires directly to the AC lugs of bridge rectifier?
That eliminates the wire run to the eyelet board.

[czech-one-2]

Ok, got it wired up per diagram and its quiet! Meaning no sound through the speakers. The 6l6's are glowing beautifully and nothing is blowing up...but no sound.
I need to replace the 25uf/25v cap cause its under rated and getting hot. I'll post some photos if any of you find something or have a suggestion as to how to trouble shoot this please let me know!

[jmaf]

Caps can't get hot at all, there's something wrong. Maybe it's heat radiating from the 10W brick resistor?

You used red wires for both positive and negative, so it's hard to see now where which polarity went. If you're sure you didn't invert the polarity, then it's time to bring out the multimeter and start checking the high voltages. Again if the cap is heating you shouldn't turn it on at all, those FT caps are excellent quality they don't heat when good.

[czech-one-2]

Sorry. I had the blu/brn OT wires on the wrong pins....
Its alive! Now to see what it sounds like...

[czech-one-2]

Ok,havn't put it in its cab, only hearing it though a speaker on the table but it seems loud AND quiet!
Took some readings but as I have never owned a 6L6 amp before I would welcome any comments on how these tubes are performing and if the bias adjustment looks good.
Readings
Plate 480v
screen 476v
cathode 45.5v
cathode to plate 434v
plate current 33.5 ma

Hows it looking?
I'd like to set it up for maximum clean chime and clean headroom.

[nickb]

Ok,havn't put it in its cab, only hearing it though a speaker on the table but it seems loud AND quiet!
Took some readings but as I have never owned a 6L6 amp before I would welcome any comments on how these tubes are performing and if the bias adjustment looks good.
Readings
Plate 480v
screen 476v
cathode 45.5v
cathode to plate 434v
plate current 33.5 ma

Hows it looking?
I'd like to set it up for maximum clean chime and clean headroom.

I think the bias is about where it should be. It's really not possible to be certain without using a scope. You could try lowering the cathode resistor to get so no higher than 60mA plate current and see if it sounds any cleaner to your ear.

The only way to really get more headroom would be to use a 4 ohm speaker instead of 8. That will double the output power assuming the driver is up to the job.. You can use two eight ohms speakers in parallel and they will work together to make it louder still.

We don't know how well the driver stage is doing. Again a scope would be best to answer that. That is a pretty big unknown.

[czech-one-2]

Ok, hooked it up to a 4x10 oxford 8ohm cab and it sounds Strong! The BASS is a little too solid, and I'd like a bit more chime out of the top end.All in all I'm quite pleased! Its certainly loud for a 12w amp and very little background noise.
Any suggestions for lowering the bass content and making it a bit brighter?

[jmaf]

You can install a 100pF capacitor across the volume control input and wiper terminals to increase brightness.

[nickb]

Ok, hooked it up to a 4x10 oxford 8ohm cab and it sounds Strong! The BASS is a little too solid, and I'd like a bit more chime out of the top end.All in all I'm quite pleased! Its certainly loud for a 12w amp and very little background noise.
Any suggestions for lowering the bass content and making it a bit brighter?

One at a time,
change the 0.0047uF in the input 0.0022uF
change the 0.01uF on the plate of V1A to 0.0047uF (edited from typo 0.047uF)

There really is no way to add top end as you need more gain and that means more tubes. You can only lower everything else and then you might find the gain is too low. If you want to experiment try changing the V1B 10uF cathode to something like 0.22uF.

You try change just one of these and vary the cap value to see what you like.

[czech-one-2]

Thanks you guys! I've always heard [read on forums] that that .01 cap increases bass as you go bigger. Some recommend .022 but say .047 can add too much bass. Is this completely backwards?
Most people jumper that .0047 but I tried that with my other MMB amp and found it added bass, so I like that cap there. I'll try a .0022!

[czech-one-2]

Jmaf, the 100pf cap really brought out the upper high end. I suppose this is the Fender 'bright cap' that people remove in their Deluxe Reverb amps? I like it, so its staying put!

[czech-one-2]

Jmaf, that 100pf cap really sounds nice. Brought the upper high end forward. I suppose that is the Fender 'bright cap' that people remove in their Deluxe Reverb amps?
I'm open to any more suggested tweeks to this circuit. Tone stack etc. But I could happily take this amp to a gig as-is.
Also, while I'm here I'll throw this out. Do any of you know someone who can make a head cabinet for this amp [in the EU] ? It sounds great through my [huge] 70's Randall Commander 4x10 cabinet. The Musicmaster Bass chassis is identical to the Fender champ chassis in all dimensions.