5E3 clean headroom

[Stevem]

Great point Leo and often overlooked!
The one output tube working ( lit up but not working maybe) deal is amazing in how little clean volume any two output tube amp will have!

[hebaton]

… I discovered the volume pot some time ago

So if you turn the guitar’s vol control down a bit, can you get a loud, clean sound out of the amp? eg loud enough for someone trying to watch the telly in the next room to get rather annoyed.

Not so, that'S the issue or a result of it. At the clean volume I can play in the next room without bothering someone. If the door is shut. but that still feel much under what it is supposed to be.
THe speaker is a brand new Jensen P12Q ( 94.4 DB 1W/1M )

[frankdrebin]

you can play humbuckers like old style pafs,which have less output and not so mid heavy like modern ones,but you still need to adjust guitar volume and play with the amp 2 volumes,once you turn up the unplugged channel it can clean up a bit.
Anyway,it's an old debate,many think that it's the volume taper causing too much signal on the second stage and so on,in reality it's the nature of the pot wiring,which is not a voltage divider,but a loading device to the next grid.
this is one of the best videos you can get inspiration:

[pdf64]

… I discovered the volume pot some time ago

So if you turn the guitar’s vol control down a bit, can you get a loud, clean sound out of the amp? eg loud enough for someone trying to watch the telly in the next room to get rather annoyed.

Not so, that'S the issue or a result of it. At the clean volume I can play in the next room without bothering someone. If the door is shut. but that still feel much under what it is supposed to be.
THe speaker is a brand new Jensen P12Q ( 94.4 DB 1W/1M )

Ok, fair enough, though bear in mind that’s one of the lowest efficiency guitar speaker types available. eg a Celestion G12H30 (100dB @ 1W) would be significantly louder.
To progress this, if you can do so safely, you’ll need to get busy with your meter (VDC in the oblong boxes) on the test points noted on the schematic / layout.
TPs 1, 2, 6, 8, 10 & 11 probably being the most pertinent.
Or take it to a competent tech.

[Leo_Gnardo]

So if you turn the guitar’s vol control down a bit, can you get a loud, clean sound out of the amp? eg loud enough for someone trying to watch the telly in the next room to get rather annoyed.

Not so, that'S the issue or a result of it. At the clean volume I can play in the next room without bothering someone. If the door is shut. but that still feel much under what it is supposed to be.
THe speaker is a brand new Jensen P12Q ( 94.4 DB 1W/1M )

Ok, fair enough, though bear in mind that’s one of the lowest efficiency guitar speaker types available. eg a Celestion G12H30 (100dB @ 1W) would be significantly louder.

pdf64's Celestion suggestion is a good one. Another example from real life, a customer I hadn't seen in some time brought in his tweed Deluxe for a little service work. I had forgotten, he had shoe-horned an Altec 417 into this cab. The magnet cover came within 2 millimeters of preamp tube V2. Tight fit! But the sound, wow... totally out of sight. If you want to go ultimate, find yourself an old 417. It will make the most of what your amp can deliver. Nobody makes anything like that anymore. For a lot cheaper, sure that Celestion, and a number of other competent speakers can turn out + 6 dB volume over what you have, a noticeable chunk. But I had to put in a word for the Altec. It's the bees knees!

One warning though, if your speaker baffle is thin wood, especially old and dried out, you should have it replaced with a sturdier support for any heavy speaker. Don't find out what can go wrong the hard way.

[hebaton]

Here are some readings:
Output tubes PLates-366v, screens-320v, cathode 19.8v
12AY7 pin 1-118v, pin 4-120v
12AX7 pin 1-163v pin 4-193v
C1- 366
C2- 313
C3- 260

I watched the video and the clean tone this guy is getting simply do not exist on my amp. With a 335 pluged in the bright channel guitar volume up tone centered bright channel volume at the point of unset , when sound comes on, I get a light crunch.

[pdf64]

Here are some readings:
...

That all looks fine.
Without the amp on a test bench with sig gen, scope and dummy load, the best I can suggest is to try different valves, speaker.

[hebaton]

COuld it be about parts quality ? or a wrong resistor value somewhere

[hebaton]

Here are some readings:
...

That all looks fine.
Without the amp on a test bench with sig gen, scope and dummy load, the best I can suggest is to try different valves, speaker.

I may have found something. THe 5E3 calls for 68k resors at R3,4,5 and 6
all of those on my amp read 34K

[Stevem]

Changing those out to the as Fender built 68K will only make a very slight difference in signal level and trim off some top end.
A easy test to make and you only need your ear to do it is to pull out one output tube at a time and see if you loose all output, if you do then you have found the issue.

Also I can’t tell you how many amps over the years I have worked on a amp where the new owner just got it and was thrilled that it had NOS output tubes, and as it turned out the seller put in tubes that where flat out shit and dead!

[pdf64]

…THe 5E3 calls for 68k resors at R3,4,5 and 6
all of those on my amp read 34K

The switching arrangement on the input jacks puts them in parallel (ie R3//R4 & R5//R6), so that’s completely normal and to be expected.
If you desolder and lift a leg, the now isolated resistor will almost certainly measure 68k.