Ashdown ABM 500 EVO III Tube roll...

Sliderbass · #1 12-01-2010, 11:00 AM

Just got one of these and was wondering if its worth the effort to open it up and try a few different tubes in its preamp. Has anyone tried this with this version yet?

Wonder if it's like the Eden Navigator where any tube sounds the same...

fenderhutz · #2 12-01-2010, 11:09 AM

I always use a JJ tube in my preamp section. Regardless of amp.

http://thetubestore.com/tesla12ax7.html

Good overall, high gain, low noise. It's subtle difference with preamp tubes, but I can tell.

45cmckay105 · #3 12-02-2010, 06:11 AM

+1 on the JJ.

Switched out my Hartke LH500 PreAmp tube to a TungSol and like their 12AX7 as well.

Between the two, I would give the nod to the JJ.

Although, same JJ tube in my SWR Headlite really didn't do much.

isorokko · #4 12-02-2010, 06:20 AM

Quote:

Originally Posted by 45cmckay105

+1 on the JJ.

Switched out my Hartke LH500 PreAmp tube to a TungSol and like their 12AX7 as well.

Between the two, I would give the nod to the JJ.

Although, same JJ tube in my SWR Headlite really didn't do much.

Sorry for a quick OT, but would you say the difference is audible in the LH500, might change the tube on mine if so.

Sliderbass · #5 12-02-2010, 08:06 AM

So I grabbed my "bag-o-tubes" and my screwdriver and went at it. After a couple of hours and about 6 different tubes, I settled on an old RCA 12AX7(red logo). You can blend the amount of tube drive with this head and this tube seemed to sound smoother than the rest.

The "rest" were, in no order:

Tung-Sol -- seemed very bright, too bright

Sovtek (short & long plate) -- same as above

GE -- almost exactly like the RCA but just a little less smooth around the edges

Lafayette -- made almost no difference even with the tube gain all the way up. Thinking this tube is bad.

RCA-5751 -- Just tried on a whim to see how it sounded with the tube drive all the way up. Very quiet just as it should have.

Again this is all really subjective but the RCA i put in seemed to me at least to sound best out of the ones I had on hand to test. I did go back and forth between the stock tube(A Chinese made, no brand on it 12ax7)and I did hear a difference between them. Not as night and day as changing V-1 in a DB-750 but a improvement to my ears at least.

No really cool or rare tubes in my small stock but it was a fun way to kill some time on a cold & rainy weekday(oh yeah, did I mention that it was more fun that my day job???)