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Ceriatone => Overtone => Topic started by: 212Mavguy on November 17, 2010, 04:37:05 AM



Title: Any tube collectors' views on what vintage tubes for a stock HRM amp?
Post by: 212Mavguy on November 17, 2010, 04:37:05 AM
First time Ceriatone owner here, waiting for a new 50w HRM to arrive.  I have a couple hundred vintage 12ax7's, (almost any kind that have ever been made,) and a decent variety of 5751's and 12at7/6201's. 

For the power tubes I have some vintage 6l6g's, 5881/6l6wgb's, vintage el34's by Siemens and Tesla, a couple pairs of GEC kt66's, a few pairs of Bendix 6384's and adapters.  Also picked up a pair of TAD short bottle 6l6gc's. 

I am expecting some excessive brightness for the first hundred hours or so until the caps form and the OT seasons.  To be honest, I won't want to stick any modern production preamp tubes in it...

Am interested in your tubing suggestions, and reasons why they work for you.  I have a few Heritage brand guitars, all have humbuckers.   Frankly I'm surprised at all the posts about circuit tweaking and conversely so very little from the tube selecting/bias setting side of amp voicing. 


Thanks!


Title: Re: Any tube collectors' views on what vintage tubes for a stock HRM amp?
Post by: mcinku on November 17, 2010, 06:59:44 AM
Man if I would have a tube collection like you I would definitely invest in something like this...
http://www.youtube.com/watch?v=xke4OPpFfas (http://www.youtube.com/watch?v=xke4OPpFfas)

Just my thoughts about your comment ...
Quote
Frankly I'm surprised at all the posts about circuit tweaking and conversely so very little from the tube selecting/bias setting side of amp voicing. 

...I don't want to build my tone around some expensive NOS tubes... these are hard to get and even harder in the future I guess and not to mention expensive.... I rather use something which is easy to get and tweak the amp from there. That's probably why people here don't focus on tubes that much... after all, we decided on C-tone because we're smart with our $$$.  ;)


...and welcome to the forum.


Title: Re: Any tube collectors' views on what vintage tubes for a stock HRM amp?
Post by: bluesfendermanblues on November 17, 2010, 10:43:08 AM
Man if I would have a tube collection like you I would definitely invest in something like this...
http://www.youtube.com/watch?v=xke4OPpFfas (http://www.youtube.com/watch?v=xke4OPpFfas)

Just my thoughts about your comment ...
Quote
Frankly I'm surprised at all the posts about circuit tweaking and conversely so very little from the tube selecting/bias setting side of amp voicing. 

...I don't want to build my tone around some expensive NOS tubes... these are hard to get and even harder in the future I guess and not to mention expensive.... I rather use something which is easy to get and tweak the amp from there. That's probably why people here don't focus on tubes that much... after all, we decided on C-tone because we're smart with our $$$.  ;)


...and welcome to the forum.


Great tool....but how about just building a small fender tweed champ like this one: http://ceriatone.com/productSubPages/ACChampUltra/ACChampUltra.htm

Like the Univalve it uses ONE preamp tube and ONE poweramp tube. It's self biasing (because its a cathode biased class design), so in effect it'll let you try you whole collection of preamp tubes , one by one ,as well as your poweramp collection. An let your ears decide what sounds best. I have a homebrew champ that I use just for that.

You gotta make sure, though, that the power transformer will be able to deliver 1.5A of heating current, if you want to try EL34/KT66/KT77/KT88 tubes.


Title: Re: Any tube collectors' views on what vintage tubes for a stock HRM amp?
Post by: mcinku on November 17, 2010, 11:04:30 AM

Great tool....but how about just building a small fender tweed champ like this one: http://ceriatone.com/productSubPages/ACChampUltra/ACChampUltra.htm

Like the Univalve it uses ONE preamp tube and ONE poweramp tube. It's self biasing (because its a cathode biased class design), so in effect it'll let you try you whole collection of preamp tubes , one by one ,as well as your poweramp collection. An let your ears decide what sounds best. I have a homebrew champ that I use just for that.

You gotta make sure, though, that the power transformer will be able to deliver 1.5A of heating current, if you want to try EL34/KT66/KT77/KT88 tubes.


Well using amp is not as convenient... (I'm talking pre amp tubes here)... with this device you really can hear the subtle difference which can't be heard with the amp like that... and also this way you can see what certain tube does to whatever specific amp you're testing with... not o mention the OD side as well. We all know some tubes work better on the clean side and some are better for OD...


Title: Re: Any tube collectors' views on what vintage tubes for a stock HRM amp?
Post by: 212Mavguy on November 17, 2010, 02:29:41 PM
Wow!  Thanks for your replies, the welcome, and the civility in your words. 

On the Champ thang, that's how I currently evaluate my tubes.  I like the tube roller thang, but I already have a testing unit that works well. 

And yes, NOS tubes are too expensive.  Plus they frequently don't sound as good as well broken in ones, too bright and brittle.   I buy mine as VOS (vintage old stock) USED, and frequently for prices not much more than new production units...on eBay.  Have picked up Amperex, Siemens, and Mullard long plate 12ax7's for easily less then 40 bucks each that way, for instance.   That's not too expensive. 

I have a Hickok Cardmatic and test them in it, mark results on the bottle, and then roll them one at a time in a single ended amp.  It's a silverface Champ, has no Fender parts anymore except the power switch, the light, the pots, and the cab.  I populated a blackface turret board with tantalum resistors, F & T electrolytics, Black Gate cathode bypass caps, Jensen copper foil PIO tone caps.  The PT is oversized, the OT is a monster sized 5k primary 30 watter that had to be mounted in the bottom of the cab with t-bolts, am using the 16 ohm tap.  The power tube socket has pins 1 and 8 connected, so I can and do run el34's, kt66's, and even 6550's in it, plenty of filament current available for the heaters from the PT.  Then I lifted the 10k resistor from the bass pot going to ground.  The ground is now a bus rather than the chassis.  The gain as a result of lifting that bass pot ground is pretty monstrous.  The tone controls don't really work anymore, the bass pot has no effect, the treble very little, all the way down sounds more mid scooped, all the way up is more mid focused.  So get a good palette of tone from clean to scream.  Easy to spot  a microphonic tube in that setup too. 


Title: Re: Any tube collectors' views on what vintage tubes for a stock HRM amp?
Post by: mcinku on November 18, 2010, 06:42:54 AM
You're right about something...

we tend to be more civil here, compared to some of the other places I've been lately...
 ;D


 ;)


Title: Re: Any tube collectors' views on what vintage tubes for a stock HRM amp?
Post by: 212Mavguy on November 19, 2010, 05:48:20 AM
Yep, the folks here are kind for sure.  Also that way on the Heritage guitar owner's forum.  Not a big fan of the HC forums, they are out of control in not a good way. 

But back to the original post, if there are any vintage preamp and/or power section tube faves that you have enjoyed in a 50w HRM I'd be interested in what and why the selections you tried were pleasing to you...

and thanks to all!!


Title: Re: Any tube collectors' views on what vintage tubes for a stock HRM amp?
Post by: mcinku on November 19, 2010, 06:16:07 AM
Sorry not much experience with NOS tubes, except I have one EI tube, which sounds really good in my OTS. It sounds much clearer and brighter compared to Tung-Sol I'm using right now.


Title: Re: Any tube collectors' views on what vintage tubes for a stock HRM amp?
Post by: 212Mavguy on November 19, 2010, 02:22:48 PM
Thanks!  I have some EI's, both gray and "silver bullet" types.  Will roll a grayplate when the amp shows up, guessing that will be in January sometime, since the order date was Oct 28th. 

FWIW, it's best to refer in print to modern production Tungsols by placing the "RI" (re issue) suffix after the tube name type, as in Tungsol 12ax7 RI.  The ones made today are in no way similar in build or tone to the originals. 

The originals are warm, fat, smooth, and gorgeous sounding, lots of detail in the lower and upper mids, they would go well in a slightly too bright amp for instance. 


Title: Re: Any tube collectors' views on what vintage tubes for a stock HRM amp?
Post by: dt125 on November 19, 2010, 05:59:12 PM
Hi,
Ive had a 50w HRM for about a year now and tried out lots of different tube combinations including NOS and I have settled on the following:

 V1 NOS Brimar 12ax7,
 V2 NOS GE 5751,
PI balanced JJ 12ax7
Power tubes are TAD 6l6 WGC

I found i preferred the Brimar to an old Mullard I tried and the 5751 really does smooth out the gain. Not experimented too much with the PI but the JJ seems ok, the TAD WGCs made a difference to the whole feel of the amp and I highly recommend them


Title: Re: Any tube collectors' views on what vintage tubes for a stock HRM amp?
Post by: 212Mavguy on November 19, 2010, 07:21:14 PM
AWESOME!  Now we're talkin! 

I have examples of all the tubes you suggested except the JJ for the PI slot.  I do have several VOS Tesla ecc803s/e83cc, forbears to the JJ.  They are smoother with more harmonic content, they make wonderful copies of the signals coming from earlier in the tone chain. 

More suggestions are welcome!   Saweeeeeet!   


Title: Re: Any tube collectors' views on what vintage tubes for a stock HRM amp?
Post by: boldaslove6789 on November 19, 2010, 09:02:09 PM
I've been using amperex ecc83's in V1 & V2 for a few months now and they're on the top of my list for some of the best ecc83/12ax7's ever made.I got a bunch in a trade but they run about $100 a piece at NOS tube outlets.

 Don't really like them in the PI (I prefer Tung Sol 12ax7's there) but I usually have to weed out a bunch to find the good ones because they're failure prone.

 As far as output tubes go I'm diggin a quad of Svetlana 6L6GC's


Title: Re: Any tube collectors' views on what vintage tubes for a stock HRM amp?
Post by: 212Mavguy on November 19, 2010, 11:36:40 PM
Cool!  Great to hear from you!  Amperex 12ax7's are one of my fave pre's.  They are brighter than Mullards most of the time in the shortplate version. 

Thanks so much, and please keep the suggestions coming! 



Title: Re: Any tube collectors' views on what vintage tubes for a stock HRM amp?
Post by: boldaslove6789 on November 20, 2010, 07:26:49 PM
BTW, I was using Sovtek 5751's (lower gain version of a 12ax7) or Amperex ECC83's in my dumbleator for a while but recently switched it to a Telefunken smooth plate ECC83 and it sounds f'in fantastic. Although Telefunkens are talked up to be the best tubes ever made (which is just snake oil in my opinion), I wanted to try one in my d-lator and got a good tested one from a friend. The biggest difference in sound IMO is that it compressed the sound in a different way than that of other 12ax7 I've tried. I would recommend one in the d-lator but it is objective however that they sound good in certain d-style amps. Steve Kimock swears by them apparently but I wasn't diggin em'.

  Another tube that I like in my BM (In the PI and V2) is new production Mullard ECC83's (New Sensor I think?)


Title: Re: Any tube collectors' views on what vintage tubes for a stock HRM amp?
Post by: 212Mavguy on November 20, 2010, 11:27:41 PM
Hi and thanks for the 'funken suggestion!   Best 12ax7's ever made???  Definitely NOT!  What sounds the best in one circuit to a person's ears will not sound the best in another circuit to that same set of ears.  Even more so when considering the amp families that are represented under the Ceriatone banner.   Marshall, Fender, Trainwreck, Dumble, Matchless, Hiwatt, etc.  Each family has it's own type of voice.  For instance, RCA 7025 shortplate is THE classic V1 Fender tone tube.

I have a few TFK smooth and ribbed plate 12ax7's and a few 12at7's as well.  I know what you mean about the sound qualities of the smooth plate, they have great control over their harmonics when overdriven, and are more compressed and smooth sounding than most 12ax7's. 

Similarly, the ribbed plate versions are also compressed when pushed, have excellent control over harmonics, and tend to have more top end to their tones overall than the smooth plate version, both types do the smooth sounding violin type sustain VERY well, the smooth plate will take more gain before it starts to get a bit bright on the top end edge of the tones and that takes serious amounts of gain to ever get there.   Thinking about that, I could easily see where a smooth plate might give up a tone through a c-lator that would be reminiscent and supportive of the original OTS, while a rib plate might give up the kind of tones toward the direction that the HRM's are known for.  I will definitely remember to try both types out! 

And in the FWIW department, their 12at7's are simply gorgeous sounding clean or dirty, and i have some very top end at7's to compare them to.

We are building a very nice and special thread, so please keep the posts coming.  Good things are here because of YOU! 


Title: Re: Any tube collectors' views on what vintage tubes for a stock HRM amp?
Post by: mr fabulous on November 21, 2010, 01:50:39 PM
HI MAV GUY

the topic on preamp tubes has been done to death here i reckon...

but for what its worth:

at present i am using:

V1: sovtec
V2: JJ (smoother and a little more compressed for overdrive)
V3: reissue mullard .. seems to dive Output stage harder

output tubes: winged C...... excellent tubes


Title: Re: Any tube collectors' views on what vintage tubes for a stock HRM amp?
Post by: 212Mavguy on November 22, 2010, 01:34:54 AM
Thank you!   Done to death???  Naaaah.  Not if we keep learning from each other...  Better to have more inputs...especially more on vintage power tubes.  Keep 'em coming! 


Title: Re: Any tube collectors' views on what vintage tubes for a stock HRM amp?
Post by: Emiel on November 24, 2010, 03:42:37 PM
Hi,

I just ordered a JJ High gain 12ax7 (for V2) and a pair of TAD 6L6WGC-STR tubes. In my amp are currently Tung-Sol 12ax7 and SED Winged C EL34's. I also have a couple of other 12ax7's ready to test, an old Philips 12ax7, a Ruby 12ax7 and a normal JJ 12ax7. As soon as I'll receive the JJ/TAD package I'll try them all and write my thoughts here.

Cheers :)
Emiel


Title: Re: Any tube collectors' views on what vintage tubes for a stock HRM amp?
Post by: bluesfendermanblues on November 24, 2010, 06:27:42 PM
Hi,

I just ordered a JJ High gain 12ax7 (for V2) and a pair of TAD 6L6WGC-STR tubes. In my amp are currently Tung-Sol 12ax7 and SED Winged C EL34's. I also have a couple of other 12ax7's ready to test, an old Philips 12ax7, a Ruby 12ax7 and a normal JJ 12ax7. As soon as I'll receive the JJ/TAD package I'll try them all and write my thoughts here.

Cheers :)
Emiel

Hmmm Winged C's (both EL34 and 6L6) are the best tubes for these amps. The Winged C 6L6 is very similar to the 70s Sylvania that Dumble used in his amps.


Title: Re: Any tube collectors' views on what vintage tubes for a stock HRM amp?
Post by: brent on November 25, 2010, 09:50:56 PM
Here's my .02.

V1 - Amperex 12ax7
V2 - Amperex 12ax7
V3 - Chinese 12ax7ac (TAD, Ruby, whatever).

Powertubes.

SED "Winged C" 6L6GC-STR
TAD 6L6GC-STR
JAN Phillips 6L6WGB (early breakup with these).

Other contenders..

V1 - Baldwin Japan 12ax7 long plates (find them usd on ebay, very musical and rich).  These sound better than the RCA 12ax7s I have..
V2 - JAN GE 12ax7wa

Others I've tried..  Ei - 12ax7(ecc83).  A little brittle.  Sovtek 12ax7 - OK not great in V1 - no way in V2 on the Sovtek.  GE 12ax7 grayplate good in V2. 

Phase inverter... only tube I've found that I care for is the Chinese 12ax7s.

Amperex (holland, short plate) is the hands down winner in both V1 and V2 in my book.  I have a D-style amp, but not a ceriatone.  YMMV


Title: Re: Any tube collectors' views on what vintage tubes for a stock HRM amp?
Post by: 212Mavguy on November 26, 2010, 02:10:09 AM
Excellent, Brent! 

I have some of those JAN Philips 6l6wgb's.  They sound great. 

Baldwin labeled Japanese 12ax7 longplates???  Are you sure that they were Japanese?   There were very few Japanese made longplate 12ax7's, ever.  Perhaps you are thinking about Raytheons or Sylvanias, they made the longplate Baldwin labeled organ tubes.  The only Japanese Baldwins I have ever seen have gray short plates, with blue printing, and yes, they are very smooth and musical.

Your  preference for Chinese 12ax7's for the PI is interesting, why is that?

And thanks again, very much. for your post!


Title: Re: Any tube collectors' views on what vintage tubes for a stock HRM amp?
Post by: brent on November 26, 2010, 01:50:34 PM
These are long plates, brown lettering, and have an 8 sided box with 12AX7 printed inside on them (just like RCAs but larger).  They also say Made in Japan on them.  I just searched eBay and only saw green print sylvanias.  But these are amazing tubes, and not very well known.  I stumbled upon them accidentally when I bought 4 ANOS RCA tubes from a reputable dealer and this was one of them.  The silkscreening had rubbed off quite a bit on the original one I purchased but after getting a bunch of the Baldwin tubes (yellow, green, and brown print), I found out they were MIJ.

These are my second favorite V1 tube.  I'd highly recommend trying one when they show up on eBay.

I don't know why the chinese sound best to me in the PI.  They just sound great and strong in there.  If I didn't have these two Amperex tubes, my second choice would be this Baldwin in V1 and a JAN GE 12ax7wa in V2.  JAN Phillips 12ax7wa sound nearly as good to my ears in V2 but slightly different.  They look identical in construction.


Title: Re: Any tube collectors' views on what vintage tubes for a stock HRM amp?
Post by: brent on November 26, 2010, 02:18:29 PM
How do you guys bias your output tubes, and what do you set them to typically?  I recently picked up a bias tester that plugs into my Fluke multimeter from amp-head.  You can buy these from weber unassembled.  But for the small amount more, I picked up an amp-head mV version.

I also tried a set of Tung-Sol NOS 5881s in my amp.  They sound good!!!  But I'm saving these for my tweed Bandmaster.


Title: Re: Any tube collectors' views on what vintage tubes for a stock HRM amp?
Post by: citizen on November 28, 2010, 05:27:39 AM
Sorry if this was mentioned already elsewhere but has anyone tried a NOS Brimar in V1? Do you think this would be 'nicer' than the JJ that's in there at present?

Or would it be better used in one of the other positions?

Thanks for any advice

Kieran


Title: Re: Any tube collectors' views on what vintage tubes for a stock HRM amp?
Post by: 212Mavguy on November 28, 2010, 07:37:26 AM
Chances are significant that the Brimar would be more pleasing to many ears than any JJ.


Title: Re: Any tube collectors' views on what vintage tubes for a stock HRM amp?
Post by: citizen on November 28, 2010, 11:50:54 AM
Thanks- I will try it in there today.


Title: Re: Any tube collectors' views on what vintage tubes for a stock HRM amp?
Post by: bluesfendermanblues on November 28, 2010, 01:49:39 PM
Chances are significant that the Brimar would be more pleasing to many ears than any JJ.

After building and tweaking 4 different versions of Dumble clone amps over the last 3 years, I have reached the conclusion that jj's (ECC83S) is THE tube for position V1 and V2 and Sovtek LPS is the winner in pos V3.

My experience is the you can indeed tweak your amp to sound good with almost any tube, by tweaking the PSU string. However, I don't like my amps to stray too much from the original designs, which makes it harder to find replacements.

I have a bunch of old ECC83 tubes - mullard, brimar, Siemens, Mazda, GE - which are great in Marshall or Fender amps, but kind of pale in a D-style amp.

The amps I have now are

#124 50w version, 6L6
Bluesmaster 100W, EL34
ODS 100w, Robben Ford version 6L6
HRM Skyliner, 50w


Title: Re: Any tube collectors' views on what vintage tubes for a stock HRM amp?
Post by: citizen on November 28, 2010, 02:54:34 PM
That's interesting - the Brimar is currently in a Blackstar Artisan 15H and sounds really good in it. I also have a Brimar EF86 in the Blackstar's other preamp channel and it sounds pretty good.

I might just leave the JJ in there... decisions decisions. My amp is the Bluesmaster HRM 100- you reckon the Sovtek in V3 would be a good choice for this amp?


Title: Re: Any tube collectors' views on what vintage tubes for a stock HRM amp?
Post by: 212Mavguy on November 28, 2010, 03:25:06 PM
Only way to find out is to just do it and listen!  Again, thanks to all who have posted here, some good stuff is happening!


Title: Re: Any tube collectors' views on what vintage tubes for a stock HRM amp?
Post by: brent on November 29, 2010, 02:49:08 PM
I've been playing around with tubes over the weekend.  My amp has the effects loop buffer built-in.  Having said that, I found the best results to have the same brand tube in the V1 and also in the effects loop buffer.  I put one of my Amperex tubes in V1 the other in the loop buffer.  Put my JAN GE 12AX7WA in V2.  Left the Chinese in the phase inverter and wow! 

Anyone with a C-lator have similar experience?

I also put the SED "Winged C" tubes back in and set the bias to ~28mV. 


Title: Re: Any tube collectors' views on what vintage tubes for a stock HRM amp?
Post by: 212Mavguy on December 31, 2010, 02:10:26 PM
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!  :o


Title: Re: Any tube collectors' views on what vintage tubes for a stock HRM amp?
Post by: dt125 on December 31, 2010, 08:55:11 PM
Just wait until its broken in, it'll really come alive!  ;D ;D


Title: Re: Any tube collectors' views on what vintage tubes for a stock HRM amp?
Post by: plasticvonaband on December 31, 2010, 09:47:41 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!


Title: Re: Any tube collectors' views on what vintage tubes for a stock HRM amp?
Post by: 212Mavguy on January 01, 2011, 05:38:28 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... ;)

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.  :)

Peace.


Title: Re: Any tube collectors' views on what vintage tubes for a stock HRM amp?
Post by: bluesfendermanblues on January 01, 2011, 07:28:43 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.


Title: Re: Any tube collectors' views on what vintage tubes for a stock HRM amp?
Post by: plasticvonaband on January 01, 2011, 07:54:46 AM
i'm gonna take ya'lls advice  :) 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


Title: Re: Any tube collectors' views on what vintage tubes for a stock HRM amp?
Post by: 212Mavguy on January 07, 2011, 01:01:59 PM
@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! 


Title: Re: Any tube collectors' views on what vintage tubes for a stock HRM amp?
Post by: 212Mavguy on May 16, 2011, 05:25:31 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.