Whats on your amp workbench?

[robthemac]

Jtm45 is my favorite clean too. I didn't realise they had 6l6s in them

They didn't. It's reverting to its Bassman origins.

A few of the earliest did, right?

[Slowy]

Jtm45 is my favorite clean too. I didn't realise they had 6l6s in them

They didn't. It's reverting to its Bassman origins.

A few of the earliest did, right?

You may be correct. As I understand it, the 6L6 was an American valve, not readily available in England. Hence the change to EL34.

Edit:
Early versions used 6L6 or US 5881 valves (a version of the 6L6[6]) in the output stage; later models used KT66 (from 1964), EL34 (from 1966), or KT88 (from 1967; in the 200W Major), and ECC83 (12AX7) valves in the pre-amplification stage.

[sizzlingbadger]

KT66 is where the magic clean tone is, if you can afford them

[sizzlingbadger]

For those interested in building amps and want a good reference for good build techniques then parts of this online book may be an interesting read. It's very similar to what I was taught by the UK MOD when I worked in the nuclear industry.

https://workmanship.nasa.gov/lib/insp/2 ... meset.html

[jeremyb]

Spent the afternoon trying to sort out some madness in this Bluesbreaker Reissue 1962

Came with random grounds missing, trem not working (not intentionally), LarMar Master Volume, Cathode Bias with 6V6 tubes.

Have disconnected the Trem from the circuit properly and changed the mixing resistors to JTM45 spec. Changed back to fixed bias with non-master and got some 6L6GC’s in there and it sounds a lot more frightening in the best manner.

IMG_5342.jpeg

IMG_5343.jpeg
Basically all that getting reversed.
Reason is that I actually bought this amp because JTM45 corn is my favourite clean tone ever, so I give no craps about early breakup, I want deep vibey clean.

Had an absolute mare of a biasing time - had got a new bias probe because old one broke but new one is useless. I figured out that it was useless one I realised that the number I was seeing on the dmm wasn’t the current like I expected. Dumbass me thought oh well I better go and parallel a resistor to get the bias in the right zone. Had a few moments of the tubes biased at 120% until I figured out what was going on and went to transformer resistance bias method.

Going to pop in a cross line master vol and a cut control and see how I like that. If I’m not a fan I’ll go back to LarMar. Also considered making it switchable fixed or cathode biased.

The thing that’s looming is that Marshall have installed the Power Transformer on the wrong orientation so will need to rotate it - will require making the chassis hole wider to fit the other orientation which I am not looking forward to.

This video appeared in my feed and I thought of you!

[Jay]

Wanted to test my new amp with my new speaker asap without building a new cabinet...

What follows is a baffling story



























Argh, ran out of 6mm bolts

[jeremyb]

Excellent!

[Bg]

On one of my benches…

Heater wiring left to do

[MikeC]

Heater wiring, worst job. I always do it first!

[Bg]

Heater wiring, worst job. I always do it first!

That’s why I left it till last

[TmcB]

Just did the Larry grounding scheme on my Bluesbreaker and my word does it make it quiet. 10/10 mod

[MikeC]

Just did the Larry grounding scheme on my Bluesbreaker and my word does it make it quiet. 10/10 mod

Googles "Larry grounding scheme"...

[TmcB]

Just did the Larry grounding scheme on my Bluesbreaker and my word does it make it quiet. 10/10 mod

Googles "Larry grounding scheme"...

larry grounding scheme jtm45.jpg (81.71 KiB) Viewed 2067 times

The TL;DR is really getting all the grounds off the buss wire on the back of the pots and connecting them to bolts in the chassis in thoughtful groupings. I didn't move the heater or OT grounds on mine though, seemed odd to traverse the whole chassis

[MikeC]

Heater CT to input jack grounds - weird but if it works...

[TmcB]

Heater CT to input jack grounds - weird but if it works...

I know right...I didn't do it myself