Difference between JMI AC30 and AC30TB

drbob1 · #1 05-10-2005, 07:39 AM

I'm going to have to thin down the herd for a move. I have an AC30TB combo with blues coming, and an AC30 non-TB with silver Bulldogs that's not super healthy, so I'm not sure a direct comparison will be helpful. What is the difference in sound between the two (besides the obvious increased EQ choices with the TB)?

QuickDraw · #2 05-10-2005, 07:41 AM

does the non topboost ac30 have ef86's in the preamp?

drbob1 · #3 05-10-2005, 08:35 AM

I don't think so, it's a grey panel (so 64-65) so it should be 12AX7s, right? Didn't the EF86s go out with the AC30/4s?

Kiwi · #4 05-10-2005, 12:20 PM

You might ask this question over at the Plexi/Vox board:

http://vintageamps.com/PlexiPalaceUB...?ubb=forum;f=2

Lots of vintage Vox guys over there....

Kiwi

drbob1 · #5 05-12-2005, 10:33 AM

Well, no answer from the guys at PP. Anybody?

On another note, there's a guy over there who'll mod any JMI AC30 to AC30/4 specs. For the combo with the wrong speakers or the head with the replaced PT, that's very tempting!

QuickDraw · #6 05-12-2005, 10:45 AM

i got a book at home with some info, i'll try to post some tonight, but if it was me i wouldn't mod it, i believe the silver speakers are the same as the blues, what is not healthy about the amp?

QuickDraw · #7 05-12-2005, 05:41 PM

ok, this is from "the tube amp book 4.1th edition" by aspen pittman, which i strongly advise anyone to buy, great book!

"the top boost is definatly the best sounding of the bunch because it had 2 extra ECC83 preamp tubes and a complex tone boost section that gave it extra punch compared to the standard ac30"

"the ac30 was also available with reverb or extra gain in the tone section-- they were either labled ac30 rev or ac30 top boost."

hope that helps, btw i run a home for sick ac-30s if it needs a home

you may also want to try a dallas rangemaster with the non top boost, as they sound great on the normal channel of the ac30

guitarman_1 · #8 05-12-2005, 08:00 PM

The ac30/4 was the one with the ef 86. After they went to the ac30/6 it became a 12ax7. Im sure there maybe some rare exceptions, but that is the rule. Now on the ac15 you get a ef 86 preamp tube up into the mid 60's. Hope this helps, as I have a 1961 ac30/4.
Thanks.
O

drbob1 · #9 05-12-2005, 10:01 PM

Quote:

Originally posted by guitarman_1
The ac30/4 was the one with the ef 86. After they went to the ac30/6 it became a 12ax7. Im sure there maybe some rare exceptions, but that is the rule. Now on the ac15 you get a ef 86 preamp tube up into the mid 60's. Hope this helps, as I have a 1961 ac30/4.
Thanks.
O

Now that's an amp I'd like to play. Actually there's a guy who'll rebuild a JMI AC30 to AC30/4 specs. Would it be worth sending one of the non-original ones to him? Is it different/better enough to be worth further modding a JMI?

guitarman_1 · #10 05-12-2005, 10:21 PM

I cant say which is better, They all have their strong points. I like the chime of the 65 tb model with a strat. The ac30/4 is darker more marshall voiced than the 12ax7 model. It also has more gain. Mind you it has chime, just in a different vein,but witha Lester the ef 86 front end is a killer.. I will say, The ac30/4 is very special.I dont know how the reworked ones would sound, but i would probaly try the mod on a re issue first.
Hope this helps.
O

Sir EL84 · #11 05-13-2005, 01:43 AM

Hi,

I don't have his name, but there's at least one person who builds the EF86 channel into a rear mounted unit much like the early Top Boost retrofit add on. This can be added to any AC30 w/o losing what you already have.

drbob1 · #12 05-13-2005, 09:38 AM

Quote:

Originally posted by Sir EL84
Hi,

I don't have his name, but there's at least one person who builds the EF86 channel into a rear mounted unit much like the early Top Boost retrofit add on. This can be added to any AC30 w/o losing what you already have.

Now this would be VERY useful. Any idea how one might find him?