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ADA Preamps => MP-1 Classic => Topic started by: Explorer84 on December 06, 2014, 06:21:45 AM

Title: Why is the MP1 Classic so hard on tubes?
Post by: Explorer84 on December 06, 2014, 06:21:45 AM
Hi all, I bought My MP1 Classic used a few years ago, the tubes that were installed have no markings at all, I presume these are the original stock tubes? these tubes work just fine,

however, we all like to tinker with our gear right?, so a while ago I bought a bunch of old NOS and new 12ax7 tubes just to play around with, see what tones I could get with these tubes,
I also tried some 12ax7s from my other amps and MP1s,

a lot of these tubes began to die in the MP1 Classic after a few minutes playing?,
I presumed that any brand, any regular 12ax7 would work without any problems? am I missing something?, does the MP1 Classic require something different to a regular 12ax7?

I put the original 'no name' tubes back in and it has been working fine ever since

stumped?  :dunno:
Title: Re: Why is the MP1 Classic so hard on tubes?
Post by: rnolan on December 06, 2014, 06:46:41 AM
Any brand 12AX7 should work fine electrically  :thumb-up: although they all sound different... From recent experience (tubes dying in MikeBs MP1), I'd change the tube sockets.
Cheers R
Title: Re: Why is the MP1 Classic so hard on tubes?
Post by: MarshallJMP on December 06, 2014, 09:34:09 AM
With the dead tubes,did you see the filament glowing?
Title: Re: Why is the MP1 Classic so hard on tubes?
Post by: Explorer84 on December 06, 2014, 09:46:20 AM
With the dead tubes,did you see the filament glowing?

Hi there, no I didn't make a point to look at the tubes, the sound level just kind of faded lower and lower
Title: Re: Why is the MP1 Classic so hard on tubes?
Post by: MarshallJMP on December 06, 2014, 04:44:02 PM
could you check it?maybe the filament voltage is too high.
Title: Re: Why is the MP1 Classic so hard on tubes?
Post by: Explorer84 on December 07, 2014, 06:31:42 AM
could you check it?maybe the filament voltage is too high.

Ok I tried all of the tubes that I had to hand, unfortunately I threw out all of the dead tubes a while ago, so apart from one tube all of these worked ok, all tubes have a tiny constant glow while working

so left to right:

2 x mesa tubes, these sound ok if a little flat, even though I bought these together they are a different design inside?

next with the green print, Jan 12AX7WA, this one sounds quite full tonally, but noticeably less gain

2 x Chelmer Cvc Ecc83, these are the tubes that were installed in the MP1 Classic when I got it,
for some reason I thought these tubes were plain with no markings doh!  :facepalm:
these tubes sound fantastic, now I know what they are I'll get some more, incidentally these look very similar to the Mesa tube far left in the picture,

lastly is a Harma Cryo 12ax7 from Watford Valves in the UK, I bought a few of these and they all failed including this one, it still kind of works but the output is low and it crackles and farts, I wouldn't recommend these to anyone,

from what I recall, other tubes that died in the Classic were a couple of Groove Tubes 12ax7 and a jj ecc83, there were others but I can't remember, however all of these tubes worked fine in other gear?

(http://i796.photobucket.com/albums/yy241/watchtheskies_photos/tubes.jpg)


Title: Re: Why is the MP1 Classic so hard on tubes?
Post by: rnolan on December 08, 2014, 05:05:47 AM
I'm thinking MJMP is on the money, unless you have lots of lemons, they shouldn't blow, they may sound different but not blow.
I find the Boogie tubes (typically selected JJs) a bit flat and 2D also (best feedback I've ever heard though), if you want more open 3D (very articulate) sound, the Mullard long plate or Short Plate reissues are the go IMHO, but as my mate said, they show up his mistakes LOL.
But hey, there's a reason the tubes are dying, they shouldn't unless somethings not quite right in MP1 or bad batch of tubes.