Marshall Bluesbreaker JTM 45 mods. 1962HW content

PhilTQ

http://www.raw-sewage.net/jtm45ri_mods.html

Saw this and wondered if anyone had made any changes to their head or combo?
Worth it?

ecc83

Don't know about anything else in there but Sovtek GZ34s are ***t in my experience.

Best I found was the TAD but this was a couple of years ago and quality changes all the time in the valve world!

Dave.

ICBM

ecc83 said:

Don't know about anything else in there but Sovtek GZ34s are ***t in my experience.

+1. He lost me in the first line because of that. They are the most unreliable modern GZ34 and don't even comply to the proper spec.

The Bluesbreaker reissue is actually a pretty nice amp without doing any of that. Just put a pair of decent KT66s in it (he is at least right about which ones to use), bias them on the hot side and you're there. The rest is just changing stuff for the sake of it in my opinion. Unfortunately you won't be able to get KT66s in an early Bluesbreaker reissue because the cabinet isn't deep enough - the best for those are old Chinese 'coke bottle' 6L6s.

I also think the classic 'Beano' Bluesbreaker sound *is* from Greenbacks and not Alnicos, but I know there is some debate about that.

PhilTQ

Dont know when it was written, may have been some time ago.
What about changing the can caps?

ICBM

I've never tried it, but when I restore old Marshalls I always use the standard modern 50+50uF 500V caps, and I have never once heard one that sounded worse afterwards. (Quite the opposite.)

The value should make no difference in the preamp anyway, the current draw is so small as to have no effect on the stored charge in the cap whether it's 16uF or 50uF. The reason they originally used smaller values is that back then, cap size and cost was far more dependent on the value than it is now.

The cap value will only matter in the power amp, and may cause 'ghosting' (ripple frequency modulating the audio and causing ghost notes') if the value is too low.

57Deluxe

I also think the classic 'Beano' Bluesbreaker sound *is* from Greenbacks and not Alnicos, but I know there is some debate about that.

and a perm and a shitty attitude...

ESchap

I've got a 2004 build, with the larger cab.  Not made any component value changes to it, but have changed valves with very positive results.  It had the Valve Arts KT66's in it and they are good valves, but to my ears are a bit 2 dimensional and have a slightly harsh edge when you've got the power section really working.

I put GEC KT66's in it and biased them on the hot side (40mA), and while there might be a lot of hokum about old valves, these made a very positive difference to the amp.  More dynamic cleans and much creamier overdrive with a lot of harmonics.  They do that drift into controlled feedback when you hold a note, just perfectly.  Makes the "beano" tone really easy to achieve. 

Unfortunately GEC KT66's are becoming unobtanium price wise and there are a lot of NOS advertised valves that clearly have had a very long and hard working life!  Be careful if you're buying them.

Regards Celestion Blues, I put a pair in mine.  Clean they definitely have an edge over the Greenbacks, less mid focused and much more sparkle.  However, when you crank it up into "the zone" there was really no difference at all to my ears.   I took them out in the end and put the Greenbacks back in as there was only ever going to be one result with the Blues and that would have involved getting them re-coned!

PhilTQ

I know a guy thats got a handwired Bluesbreaker. Will see if I can get some pics and info off him.

PhilTQ

Got some pics of the 1962HW:
The can cap inside the chassis is a 16+16 and the one mounted on the top is a 32+32 if that helps.

http://i237.photobucket.com/albums/ff115/Phil-tq/HW5_zpsf444dc4c.jpg

http://i237.photobucket.com/albums/ff115/Phil-tq/HW4_zps5b750879.jpg

http://i237.photobucket.com/albums/ff115/Phil-tq/HW3_zps62e81e5a.jpg

PhilTQ