electro harmonix 12ax7 bad tubes??
Georgio
i have these new electro harmonix preamp tubes and i find that they
are weak... here are my reasons..
in my JCm900, one of them turned blue one day..and that is about a week
after i bought a set (3)...got a return at the store
now..i have sold the jcm900, and i have a magnificent JMP 100 watt
super lead... i still have all the original el34 (4) and ecc83 (3) tubes..
i don't want to use these because .. just in case i'd want in the future
to sell the amp, the original tubes would still be here..( i know..i probably
will never sell it!)
anyway, the jmp now have a set of wlectro harmonix 12ax7 (mullard copies, i read
on the internet).. the preamp started to have some popping sounds when i turned
the preamp know past 7... then it started working only when i strummed hard..
using my gain pedal made it worse... after some tweaking of the preamp know, it was
now doing.."SHHHHHHHHHHH"..
so..i turned the amp off...and i thought just for fun, to put the original mullards back in..
and wadaya know...it worked fine with the mullards..i was even able to put the preamp
know at '10' and use the gain pedal..no problem here..just a high porky pig gain sound..
so. what 's going on with the electro harmonix tubes not being capable to withstand some
'sort-of' high gain??
anyone have any experience with them?
thanks in advance
georgio
--
spammers suck!!!
remover the *no spam* part in my email for reply
PMG
copy? Just curious. Because that doesn't sound right for some
reason.
I've only owned one. It came to me in a used amp. It was a rather
bright sounding tube. I didn't care for it personally, but that tube
seems to have a lot of fans. The one I had didn't seem like anything
special to me. It wasn't even all that interesting sounding.
If you've been having them die on you in short order, you probably
need to find a different source of tubes.
Pete
--
My God! It's the future. --Fry
Miles O'Neal
> bad tubes..spank..spank!!
Where did you buy them? Big Jim's Discount Tube Store?
Does Big Jim test his tubes? How?
> i have these new electro harmonix preamp tubes and i find that they are
> weak... here are my reasons..
>
> in my JCm900, one of them turned blue one day..and that is about a week
> after i bought a set (3)...got a return at the store
What do you mean it turned blue? If there was a
blue glow around the glass, this is normal. (See
the AGA FAQs at http://aga.rru.com/).
...
> anyway, the jmp now have a set of wlectro harmonix 12ax7 (mullard copies,
> i read on the internet)..
Mullard??? Or Telefunken??? Not that I
own either, but I thought they claimed
to sound like the Teles.
> the preamp started to have some popping sounds
> when i turned the preamp know past 7... then it started working only when
> i strummed hard.. using my gain pedal made it worse... after some tweaking
> of the preamp know, it was now doing.."SHHHHHHHHHHH"..
Did you pull it out and reseat it? Clean the
pins and socket? Depending on how the original
tube's pins were bent, the new tube could have
been hitting a corroded section while the other
was not.
How well they work depends on the amp and your
ears, but the ones I've used are great. I haven't
used them in super high gain amps, but I know folks
who have, and they were happy, too.
Thorny
thing with "mesa" on it) of the tube and a lot of them had failures on
the sales floor (before anyone even bought them). To me it seemed
about 1/3 of the amps had a problem with tubes or with resistors
falling off the board after a little usage. So much so that the sales
dude got pretty good at troubleshooting them after a while. You can
get bad ones of any tube. That is why it is always a good idea to get
them from LV since he screens them.
I thought that early on they did advertise that tube as sounding like
a mullard. Well that is wishful thinking. But, it can sound good in
the right situation. It has an upper mid spike but the very high end
is rolled off. It sounds pretty good if you have an overly bright amp
such as a fender or some marshalls. I like it better than the other
sovtek tubes except for maybe the LPS, I will Mike Mathews credit for
making so many varieties of 12AX7s - that makes what - 6 different
models that sovtek makes? EH, WA, WB, WXT, LPS, LP? Am I leaving any
out? I don't like the sound of the WA, WB, or WXT that much, but they
seem to be pretty reliable. I wish other companies made such a
variety.
I just repaired a 70s deluxe reverb with WAs in it, and I just had to
change that 2nd preamp tube to put some life into the amp. Every tube
I tried in it sounded better than the WA. I left all the other WAs in
there and it sounded OK. The amp sounded a LOT better with the other
tube in that primary position so I will return the sovtek to the
customer to use as a "spare." It is all about tone.
Thorny
On Sat, 01 May 2004 22:26:44 -0400, Georgio
Mike Schway
Georgio <milgs*nospam*@travel-net.com> wrote:
Like Pete said, despite what the ads say, the EH 12AX7 is NOT a mullard
clone (just like their 6L6 is "better than an RCA" and their EL34 is
also a Mullard...yeah, right!) . The new Groove Tube *may* be closer to
the old Mullard, but the jury is still out on that.
Hype aside, the EH line of tubes is not all that bad. Their 12AX7 is
one of the nicest ones to come from Russia (for whatever THAT's worth).
Fairly high gain, and IMO the non-duds are pretty reasonable sounding (a
purely subjective evaluation). Certainly less harsh and higher gain than
the run-of-the-mill Sovtek 12AX7WA.
Any particular modern manufacturer is going to have duds within a batch.
I'm getting about a 20% reject rate with EH tubes after 24-48 hours of
use. You'll notice problems more in a high gain amp (like your old
900). In a low gain amp like a non-reverb Fender Bandmaster, for
instance, the reject rate may be lots lower.
I think you may just have had some bad luck. These aren't inherently
bogus tubes, but as shipped in bulk, there are bound to be some noisy
and microphonic ones. A few vendors will do a pretty good job of burning
in and screening them before sale, however most just sell 'em right out
of the box from New Sensor.
In my experience, if they're going to develop problems, you'll see it
within a week. ANY tech or store should give you an exchange within
that period of time (if not, find another source!). This alone is a
good reason for buying locally. If, however, you do get them
mail-order, be sure the vendor does a burn-in followed by an audio
screening test at realistically high gain and has a "liberal" <g> return
policy. I won't name names, but I can think of 3 or 4 guys right off
the bat who qualify.
--Mike
--------------------------------------------------------------------
Mike Schway | [Picture your favorite quote here]
msc...@nas.com |
--------------------------------------------------------------------
Miles O'Neal
[snip]
> In my experience, if they're going to develop problems, you'll see it
> within a week. ANY tech or store should give you an exchange within
> that period of time (if not, find another source!). This alone is a
> good reason for buying locally. If, however, you do get them
> mail-order, be sure the vendor does a burn-in followed by an audio
> screening test at realistically high gain and has a "liberal" <g> return
Doh!
> policy. I won't name names, but I can think of 3 or 4 guys right off
> the bat who qualify.
Are they all listed din the AGA business pages?
Mike Schway
As a matter of fact, yes, but I'm sure that the 4 guys which come to
mind off the top of my head aren't the only ones worthy of patronage.
Miles O'Neal
>> Are they all listed in the AGA business pages?
>
> As a matter of fact, yes, but I'm sure that the 4 guys which come to
> mind off the top of my head aren't the only ones worthy of patronage.
I'm sure they aren't; I just wanted to make
sure they were all listed. Everyone who
participates can, of course.
Lord Valve
Georgio wrote:
Looks like you got some unscreened tubes, Georgio.
The reject rate on the 12AX7EH runs around 40%,
with some batches better and some worse. This
means the odds are around 4 in 10 that you'll get crap
if you buy from someone who doesn't screen them.
A good one is pretty good, though, if you like the
tone. Mesa currently ships their amps with this
tube onboard. BTW, you can't screen preamp
tubes with a tube tester - I've seen tubes that
tested great but sounded like poo in the amp.
I believe there is a new 12AX7 planned for Mike's
Svetlana line; if it's as good as the power tubes,
it'll be a winner. We'll see. The commies (and
former commies) who build tubes these days
are slowly waking up to the fact that if they build
better stuff, people will buy more of it and they'll
make more money. (Helluva concept, eh? It's
called Capitalism - they'll figure it out sooner
or later.)
Keep in mind that there are situations where
certain currently produced tubes outperform
even the best of the legendary NOS stuff...
and that there are many respected performers
who prefer them. I sell both, but the handwriting
is on the wall: NOS supplies are dwindling, and
the prices are rising faster than gasoline. Hopefully,
the increasing quality curve on the new stuff will
intersect the declining supply curve on the old
stuff before too long. When that happens, you'll
be able to buy those $100 Telefunkens for $10.
Lord Valve
Expert
VISIT MY WEBSITE: http://www.nebsnow.com/LordValve
I specialize in top quality HAND SELECTED NOS and
current-production vacuum tubes for guitar and
bass amps. Good prices, fast service.
QSC amps, RNC compressors, lots of other good stuff!
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NBS Electronics, 230 South Broadway, Denver, CO 80209-1510
Phone orders/tech support after 1:30 PM Denver time at 303-778-1156
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steve eaton
"Georgio" <milgs*nospam*@travel-net.com> wrote in message
news:milgs*nospam*-096BDD.222...@nnrp1.uunet.ca...
> bad tubes..spank..spank!!
>
> i have these new electro harmonix preamp tubes and i find that they
> are weak... here are my reasons..
>
> in my JCm900, one of them turned blue one day..and that is about a week
> after i bought a set (3)...got a return at the store
You DO know that tubes glowing blue is a pretty normal thing and does
not mean the tube is bad don't you?
Georgio
well..when there;s no more output.. i don't find that normal
steve eaton
No, that is not normal, but then you didn't mention that either.
Sorry for trying to help.
Bill Kahle
"Lord Valve" <detr...@ix.netcom.com> wrote in
message news:40949E1D...@ix.netcom.com...
*snip*
> The reject rate on the 12AX7EH runs around 40%,
> with some batches better and some worse. This
> means the odds are around 4 in 10 that you'll
get crap
> if you buy from someone who doesn't screen them.
> A good one is pretty good, though, if you like
the
> tone. Mesa currently ships their amps with this
> tube onboard. BTW, you can't screen preamp
> tubes with a tube tester - I've seen tubes that
> tested great but sounded like poo in the amp.
My experience with this tube
has shown a similar failure rate
when buying them (unscreened)
from Mojo. (A good supplier, btw.
But for the price I pay, I can't expect
them to plug every one into an actual
circuit & test it. They do take back/give
credit for any crappy ones, though.)
For repairs, about the only two new
12ax7-types I'm using these days are
the JJ ECC83S & the aformentioned
12AX7 EH. Both sound/perform good,
but the JJ seems to be best in brighter/buzzier,
high gain amps. The JJ also seems to have more
of a "mid bump" that works better for the same
reasons.
The JJ & EH never seem to exhibit any issues
concerning
microphonics either, and that is cool.
The EH, to me, actually sounds the best between
the two.
It seems to be more linear with a very nice,
chimey high end
that the JJ doesn't possess. For the most part,
those
that have failed had some sort of heater-cathode
issue
where they'd start to hum like crazy after several
hours
of use. This was obviously an issue mainly
involving
cathode follower stages. The worst I've seen
involved a batch that had
black printing (instead of the yellow I was
getting). I had
to send back over half of what I received. ??
My favorite new 12ax7 *was* the EI but I can't
seem
to find any of the newer "shiny plate" types that
sound
good like the grey plate ones that were around a
few
years ago. Sure most of 'em rattled & squealed
like mad but when
you found a few that didn't, they were magic.
my 2 or 3 cents,
bk
MikeyMann
news:milgs*nospam*-096BDD.222...@nnrp1.uunet.ca...
>
> i have these new electro harmonix preamp tubes and i find that they
> are weak... here are my reasons..
I use the EH12AX7's and find that they are very strong tubes, very robust. I
got mine from LV, and he burns in, screens and tests the tubes, so all mine
have been fine. I've never gotten a tube from LV that went bad prematurely,
or even went bad for that matter. I also have a bunch of NOS tubes, and
strange as it may seem, I prefer the EH's. They just seem to have a lot of
"muscle" behind them, very powerful. I also picked up some JJ12AX7's, I like
them as well. I had the EH's in my rebuilt DRRI, and I just swapped them out
of V1 and V2, and popped in the JJ's to give them a try. They seem a bit
more smooth, more mellow and have a bit more in the mids, they sound VERY
nice in a Fender Blackface circuit. I'd use either tube with no problem, but
knowing the slight differences between the 2, you can select one over the
other for your specific application. For high gain, I'd probably go with the
EH's, unless I wanted the tones a bit smoother, then I'd pick the JJ's. I
could use either one and be totally satisfied.
> in my JCm900, one of them turned blue one day..and that is about a week
> after i bought a set (3)...got a return at the store
The store, in all likelihood, does not burn in or test the tubes. They
probably don't have the time or equipment to do that, they're just
interested in sales. I suggest that you get tubes from a reliable tube
vendor, that burns the tubes in, screens them, and tests them for
microphonics. If they survive the pre-tests, they'll probably survive in
your amp. At least, you'll have much greater odds that they'll last.
<snip>
> so. what 's going on with the electro harmonix tubes not being capable to
withstand some
> 'sort-of' high gain??
EH12AX7's handle high gain with no problem, they're very robust. I also use
the EH6V6's in my rebuilt DRRI. You just need to make sure that you're
getting one's that have been pre-screened and tested before you buy them.
Buying tubes from a reliable vendor really pays off, IMHO. In the long run,
you'll save money, time and lots of aggrivation. Personally, I get my tubes
from LV, and have never had a lick of trouble with any tube that he's
supplied.
Mikey
Bill Kahle
"steve eaton" <steve...@hotmail.com> wrote in
message
news:r7flc.1911$eH1.1...@newssvr28.news.prodigy.com...
>
> You DO know that tubes glowing blue is a pretty
normal thing and does
> not mean the tube is bad don't you?
> >
Hi Steve,
I disagree. Tubes in preamp
stages should never exhibit blue glow.
(except for maybe a reverb driver,
which in circuits like Fenders have
the plates at or near screen voltage)
Preamp stages normally do not have enough
potential to excite any gases.
bk
Miles O'Neal
> Preamp stages normally do not have enough
> potential to excite any gases.
Now I'm feelin' all sad for your
preamp tubes. You better be
careful; TPS (Tube Protective
Services) will be busting you
for neglect!
Zorro_2k
"Bill Kahle" <bka...@hotmail.com> wrote in message
news:BWxlc.15449$Ut1.4...@bgtnsc05-news.ops.worldnet.att.net...
steve eaton
fact noted.
thanks bill.