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| | |-+  Any tube collectors' views on what vintage tubes for a stock HRM amp?
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Author Topic: Any tube collectors' views on what vintage tubes for a stock HRM amp?  (Read 22030 times)
212Mavguy
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« Reply #30 on: December 31, 2010, 09:10:26 AM »

Just got my 50w HRM and for a couple of the first hours stuck in a Telefunken smooth plate in V1 and PI, with a Philips/Mullard 12ax7a/7025a in V2.  Vintage GE 6l6's running 34-37mv plate current.  I was stunned at the range of usable tones provided by the amp at a wide range of volumes.  Played it through a semi closed back old Peavey 2/12 Mace combo cab that I modded, filled with JBL g125's in series for 16 ohms.  Fat, full, rich.  Woooooooeeeeeeeeeee!  Shocked
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dt125
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« Reply #31 on: December 31, 2010, 03:55:11 PM »

Just wait until its broken in, it'll really come alive!  Grin Grin
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plasticvonaband
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« Reply #32 on: December 31, 2010, 04:47:41 PM »

I've got NOS JAN Phillips 6L6WGB and just fired it up two hours ago...already think it was a great decision. Very clean and articulate. I biased em to 50ma, as recommended by thetubestore.com and they are amazing!
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Overdrive is like peanut butter. Some like it crunchy, some like it creamy.
Bluesmaster 50 2x12 combo and some guitars.
212Mavguy
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« Reply #33 on: January 01, 2011, 12:38:28 AM »

@plasticvonaband

Yep, but are you sure that 50mv per tube is not too hot longevity-wise for a tube rated at 22/23 watts compared to a 6l6gc's 30 watts?    Cause that is what JAN Philips 6l6wgb's are rated at, 22-23 watts.    65% of max dissipation rating gives up some sweet tones fo sho.   The manual for HRM amps uses that 35-40mv setting advice for getting that 65%-ish zone for 6l6gc's...The wgb series of 6l6 are an older generation in the evolution of 6l6 types.  I don't doubt for a minute how great they sound, but dang, that is a VERY hot bias to run those tubes of yours at.  I have some of those tubes and yes, they sound great, big bottom, lower mids, and detailed highs, but watch how quickly those side getter flashings erode at hot, high settings!  Been there, done that, and got the t-shirt... Wink

And if you are in a dark room after they are on 5-10 minutes and see one or both of those tube's plates glowing even a bit of red, you are at or beyond those particular tubes' max ratings in your bias setting.   If I had your amp, I'd start at 28-30 mv, play through it at the lowest setting and bump up 2-3 mv at a time, playing through your amp at each setting.  You will come to a zone where you get the goods, and I'm sure it will happen at less than 50mv per tube.  Look at your manual.  My HRM manual sez 35-40mv for approximately 65-ish% max plate dissipation for a 6l6gc.  23 watts is close to 4/5 of 30 watts.  So 4/5 of 40mv is 32mv.  You might find a more than decent tone within that or up to 5-6mv higher and your tubes will live much longer than at 50mv apiece... 

I have replaced those GE 6l6gc's today in my HRM with some vintage Sylvania 6l6gc's biased at 38-ish mv apiece, and if I'm correctly informed, HAD used those tubes in many of his original builds, they sound huuuuuge in my amp.  Smiley

Peace.
« Last Edit: January 01, 2011, 12:47:31 AM by 212Mavguy » Logged
bluesfendermanblues
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« Reply #34 on: January 01, 2011, 02:28:43 AM »

+1

50ma is much to high  - max 35-40ma.

Dumble amps like a lot of headroom. The tone is happening in the preamp, so no need for high bias.
I run 6L6 bias at around 30ma per tube.
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plasticvonaband
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« Reply #35 on: January 01, 2011, 02:54:46 AM »

i'm gonna take ya'lls advice  Smiley it sounds pretty aggressive running hot, a lil to aggressive. i turned em down to 40ma per tube, the lowest it would adjust down too. sounds a lil more tame now, in a good way
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212Mavguy
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« Reply #36 on: January 07, 2011, 08:01:59 AM »

@boldaslove6789

Your comment about the Telefunken 12ax7's got me thinking about the D-style tones i'm hearing on many youtube clips, particularly the smooth compression and harmonic bloom.  Usually they are NOT my fave guitar amp tube, but when I thought a bit about their sonic characteristics I realized that they might work well in my new HRM. 


So I found a NOS testing balanced within 10% 12ax7 smooth plate and stuck it in v1, found a strong Philips labeled Mullard Blackburn factory 12ax7a/7025a for v2, and another strong and very tightly balanced 12ax7 Telefunken smooth plate 12ax7 for the PI.  Then for the same kind of compression characteristics and brighter top end that the ribbed plate delivers compared to the smooth, I stuck a strong, balanced within 10% Telefunken ribbed plate in my C-lator.  I originally started out with a pair of GE VOS 6l6gc's, but later found a pair of VOS Sylvania 6l6gc's on fleabay with Conn organ labels on them, they run balanced within less than a half mv of each other at 38mv.  I have read that HAD used the Syl 6l6gc's in many of his builds.  To help hasten burn in, I left the amp and c-lator hooked up with all boost switches on and OD engaged all night two nights in a row without an instrument cable plugged in,  the trannies were only warm, not hot in the morning.   That made a welcome difference in the amp's tones.  Lacking a better description, the amp opened up more at given gain settings than before as far as harmonic content.

I got exactly the kind of results I was hoping for.  Without the c-lator hooked up I got everything from BF cleans to some nice Marshall-y crunch. (the first Marshall jtm45's used 5881's !!)  I love what the tone, boost, and OD trim knobs do for versatility!  Adding the c-lator without effects to the fx loop gave up the magic sustain goods I had heard, and with some very sweet harmonic bloom.  I ordered my amp with only one mod, a lift negative feedback switch. Using that flipped toward the front of the chassis smoothed out the overall tones as well, more in line with the kind of tones found in the original OTS.  Haven't touched any internal trimmers right now and don't feel like I need to.

SAWEEEEEEEEEET! 
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212Mavguy
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« Reply #37 on: May 16, 2011, 01:25:31 AM »

@dt125...

About five months of burning in have happened, the amp has opened up during that time!  I swapped a couple tubes around in the preamp from what I started with.  V1 was a telefunken smooth plate, but the amp got a bit darker after burn in so the 'funken was yanked and I stuck in a 1961 or 1962 Raytheon long plack plate 7025, in V2 I had a Mullard blackburn 12ax7 shortplate with Philips labeling.  I now have a Blackburn Microtech e813cc, made only a few months before the revived old Mullard plant finally went under and in PI the telefunken smooth plate still sits there.  I tried a bunch of different PI tubes, but the 'funken did up the best harmonic bloom at the lower gain settings on the OD channel.  Stuck some vintage Siemens el34's sitting at 39 and 42ma.   The amp has more detail overall and more harmonic richness. 
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