Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: TIMBO on June 23, 2013, 01:05:07 am
-
Hi guy's, YES, it's back :icon_biggrin: A friend was looking for an amp of about 50w as his 30w wasn't quite cutting it in a gig and he was thinking of buying a JCM800. This got me thinking about the jubilee I built, but I was concerned about some of the problems it had in its construction,one being the cab it was in and some hum problems.
So having all the necessary bits a new build was on :wav: :bravo1:
The first thing to do was to trim the crap and get back to close to the original
I can't believe (but I can really) that there was a couple of mistakes that I found when checking over the circuit board, although i was not planning to use it and doing a layout similar to ceriatone but when I looked at the work that went into it, I got lazy and used it.
A new chassis and wiring complete there were no problems on start :guitar1up :headbang: :bravo1:
Only a couple of changes to the original as marked.
I used a PT I had but it was only 300-0-300 which is ok for the EL34s but if I use the 10k dropping resistor between nodes B and C this will lower the PI and preamp voltages, so I took a stab at what that resistor would be to increase the volts down stream BUT if any one might be able to find some readings off an original or something similar would be great.
Although would it really make much difference if I left it as 10k???
The reverb is a little weak but its not really a major feature of the build but its still nice
I had plenty hum/buzz in the old build, this has no HUM/BUZZ at all :bravo1: but it does have a bit of fizz/hiss at high volume but I can live with that.
It has the typical marshall crunch even in CLEAN when maxed and tone to boot.
I found that the Master Vol works well as I can turn it down to bedroom level without it sound crap.
I'm really liking this amp as I can get the bluesy sound I been chasing.
I'll post some pics when the cab is done. Thanks :bravo1:
-
I had a Silver Jubilee here a few months ago. I really liked it a lot. It sounded awesome in every respect. Some what different than the other Marshall circuits though many of them are just the same amp with a few changes here and there
-
Hi guys, It turned out pretty good, the only thing I could have done is carved out the top above the controls similar to the marshall, it makes it a bit hard to see the control labels, but hey it all about the sound and its :thumbsup: Thanks
-
A few more :icon_biggrin:
-
Looks very nice. I wish i had a bare chassis laying around to start another build myself. Love those amps. :worthy1:
-
Timbo,
Beautiful amp and well done! That is quite impressive. Bravo!
Thanks for sharing the photos. Enjoyed seeing them.
With respect, Tubenit
-
nice work! :icon_biggrin: