Tubophiles: Replacing factory tubes in the Avalon Vt737sp

I recently bought a used Avalon 737 and have had the gall to perhaps replace the 4 factory vacuum tubes with higher quality tubes to increase sound quality and/or experiment with preAmp gain tones, Compressor tones, etc. ...
 
Also: I'm wondering if any of you are tubophiles (besides for your guitar amps).
 
Most tubes have a working life of about 5000 hours in the Avalon.
 
Avalon only recommends inexpensive Sovtek 6922 tubes for the Vt737sp.  But many producers I've read switch them out for kick a$s "vintage" tubes ... they claim to hear the difference!  I realize subjectivity plays a key role in selection (you like certain tones, etc.):
 
-- http://www.gearslutz.com/board/high-end/151305-kick-ass-tubes-avalon-737sp.html
-- http://www.gearslutz.com/board/so-much-gear-so-little-time/114069-do-you-own-avalon-737-have-changed-tubes-tube-question.html
-- http://www.gearslutz.com/board/so-much-gear-so-little-time/159025-change-tubes-avalon-737-a.html
--http://www.voiceoveruniverse.com/forum/topic/show?id=2070077%3ATopic%3A63427
(etc.)
 
Here's a quote by Eric Morgan:
"Mullard tubes are a bit darker sounding, the Telefunken are a bit brighter and bring out more of the mids and highs while they maintain the warmth."
 

NOS Mullards from Tube Depot.

papa2005


NOS Mullards from Tube Depot.

OMG,

Those guys are the worst.

Last fall, I bought out the remaining USA made NOS JAN 12AX7s from my favorite long established old school vendor for $30/each. I keep thinking... maybe he's got a stash and will pull some more out next season... but it appears that is not the case

The day I bought him out... I checked the Tube Depot and they wanted $60- for the exact same tube... but they didn't actually have any.

here's the link to that tube: http://tubedepot.com/nos-12ax7-jange.html

So, the f%7k*9rs are trying to set a market price for an item they couldn't make a market for... that's pure evil. Dante says the devil has a special place for those guys.

Furthermore, they don't have any NOS MUllards listed.

http://www.tubedepot.com/nos-6922-mullard.html

But they are willing to sell me a cool carry case for my tube stash so when I bring the collection over to my buddies place I can show it off and look all pro and stuff... no thanks it reminds me of my Hot Wheels collector case that I had when I was a kid.

Anyways,

sorry to be a downer... but that's how I feel about the Tube Depot.

On the other hand, the do seem to have the 6922 in two JAN flavors at good prices.

JAN Sylvania http://tubedepot.com/nos-6922-jansyl.html

JAN Phillips http://tubedepot.com/nos-6922-jan.html

Phillip, my advice is buy a few right now... they are gonna just become harder and harder to acquire. The most important thing, for you, is to have the opportunity to try these tubes... nothing else really matters. The opurtunity will disappear soon enough and then you will no longer get to make your own evaluation of how these older tubes may suit your taste.



very best,
mike

One problem with NOS tubes these days is that some guys are charging "collector" prices for tubes that were culled from non-collectors inventory because of "issues" like micro-phonics.

On the other hand I have often times swapped many tubes for recreation and curiousity... because I enjoy the different tones each one makes.

The fact that you can't hear the difference when swapping tubes on yer Mesa furthers my opinion that Mesa's are too complicated... the complicated just to be complicated circuit overwhelms the inherent flavor of the components. :-)

Kind of like a bad soup.

best,
mike

Mike,

Perhaps things have change at Tube Depot...I haven't ordered from them in nearly two years (haven't had a need) but I found their service & prices to be excellent...

7308 Amperex orange label USA 1960s vintage, gold pin super low noise, $300.00 per matched pair

 
$150.00 pr. tube, OUCH! They'd better be really sweet at that price.

I had my tubes tied, so I don't think they'll need to be replaced.

OK; I ordered the following tube replacements (crazy me) with instructions and how-to's ... for do-it-yourself  @ audiotubes.com (which I thoroughly researched: TBH: The tubes I ordered, I simply could find at no cheaper rate anywhere.  I hope Brent Jessee, whom I belabored, doesn't mind my sharing.
 
$620 including $hipping.

1) Siemens (German) I ordered a single @ $150: ("These have the ultra wide bandwidth of the Telefunken ECC803S, with nearly identical sonics, which are refined, smooth and accurate.")  

Two vendors, IIRC, stated these are better than the nearly extinct "over-rated" Telefunken 7308's (which I can't find anywhere!) ... noted for open "air" at the top end and "3D image" (http://www.audiotubes.com/12ax7.htm)

2) Amperex 7308 orange label USA 1960s vintage (above): I ordered a single at $150 (see above description) for air and dynamics recordings: I hope to get more clear dynamics and less microphonic noise using this one for the preamp input gain. 

Incidentally:
My Avalon 737/Neuman U87 dynamics are currently NOT that great (at all) ... especially compared to my Neve Portico / AKG414 combo.  (But the compressor-less Portico/AKG combo is so moody and dynamic that I'm about to freak out with it!)

3) NOS Mullard E188cc/7308 matched pair: I ordered his last pair @ $300.  Mr. Jessee refused to sell me one as a single!  It appears I got the last 2 in his collection.  These are touted for warmth in the mids and nether regions (lowers) ... for silky vocs and females: "haunting", etc.
 
Doubtless I will closet the 4 Russian Sovtek 6922s that are factory installed in my 'used' Avalon 737 (though I didn't detect microphonics per se in these);
 
The Avalon 737 tube chain is as follows (IIRC):
 
1) PreAmp Gain -- 2) Buffer -- 3) Output Level -- 4)Compressor
Doubtless I'll render the Avalon 737 topless for a few days/weeks or something ... and probe these 4 tubes like a perverted tubophile.   
 
... And I'll venture to keep her powered down in the process.   
 
Again, I hypothesize that my ears may hear the difference in the colorful PreAmp Gain, primarily.  I'll let you know in a week or so (perhaps with samples ... no promises).
 
Thanks again all for your thoughts and ideas!

OK, I've done prelimanary tests on the new vintage 7308 tubes (Amperex, Mullard, and Seimens)

Each of these tubes do portray slight sonic characteristics that I've studied (before the 48 hour burn in) and results so far seem 'mildly promising' only.  I wouldn't trash your Russian tubes just yet!

IOWs, the differences btw the original Russian Sovtecs and the touted Mullards ... they are mild and befit hyper tweak-heads (like me) only. 

I have performed vox tests with each tube on the Pre-Amp gain socket
... and recorded all vox tests.  If you have a serious interest, I'll publish these (Soundclick or something) preliminary results for your comparison.  Much vox validity, however, is colored by my own cr&p vox, my intermediate mic skills, and my weak recording environment.

(Feel free to pm me)

Premature Conclusions:
1) Again, the vintage tube$ while expensive ... are only 'mildly' significant (to my ears) 

2) ... they certainly do not de-ess nor change much that exists already in the factory Avalon 737.

3) The commanding dynamics of the vintage Seiman's are military-like ... but only mildly so.

4) The tube richness of the vintage Mullards are extremely mild and will go undetected by most producers ... and listeners.

5) The Amperex tube sounds almost identical to the other vintage tubes and seem to require more burn in time.

6) All the tubes are cranky and moody, requiring 30 minutes of electricity (on time) before they make your vox levels, tones, etc. ... both stable and predictable.

7) EQ and compressor settings seem much more important than tubes.  I've learned that while studying my vox phrases.

I hope this helps.  Again, I'll do further studies and be happy to share my amateur 0.00002 cents worth.

+1 Mike,

If you mean buyer's bias / expectation ...

I expected a 'moderate' improvement; but my ears only detect a mild improvement ... not worth the expen$e of the vintage.  Harshness might be better tamed with the onboard EQ and Compressor.

The harshness 'sounds' (to my ears) only slightly less than factory tubes ... no dramatic change.

I also studied Ozone4's EQ spectograph (set to infinity) on these tubes: some graphs appear to have silkier/smoother slope's with the vintage tubes ... but 'expectation' bias may be a factor here. 

Besides; the Ozone spectograph reveals little about tone and timbre; again both tone and the timbre of each tube sounds just slightly (mildly) different, one from another. 

Its no where near as dramatic as, say, special pups for your/my electric guitar that are so excellently tried and proven.  But pups are expensive.

But, I'm optimistic!  The tubes are forcing me to re-evaluate my mic techniques and EQ and compression.

Other interesting observations:

1) All (my) tubes consistently screech at 654 Hz (Q= 3-4) on some vox notes.  (easily fixable with the EQ/Compressor)

2) 'Harsh' Sibs, Plosives, and Essing is not significantly improved by tubes (despite having my U87 windshield-covered and with a pop-shield.  (easily fixable with the EQ/Compressor)

3) The Mullards alone do enrich with a very slightly more monophonic 3D tube saturation ... (?) ... which is usually not phasy or echoish (I suspect pre-echoic near surfaces here may cause phasy echoes here, too)

4) The Amperex seems slightly rounder and louder (0.3 dcbs) at times ... but its too soon to judge.

------------------------------------

I've kept the top off of the Avalon during burn-in time ... for further testings of the vintage Pre-Amp vacuum tubes. 

Yeah Mike, the room has some pre-echoic surfaces ... which I've covered with cloths in areas.

There is a significant difference after 48 hr burn-in, now.

Now that my ears are attuned I've had to work with the (1) de-ess and (2) the plosives ... currently occurring with the Mullard 7308 ...

1) With critical listening, I've managed to 'achieve' decent de-ess with 16dcbs of 8.8 kHz narrow Q pumped (hard) into sidechain compression.

2) Plosives were 'finally' decreased by lowering the pre-Amp gain to 11:00 (from center)  ... pop shields didn't help.

3) Low bass shelves: Center (12:00) and high treble decreased to 11:00.  (I have no idea why Avalon suggests raising the the 32kHz signal on the EQ; my vox required rolling off there.)

Currently I'm song recording (with the pre-Amp top off for tube swapping) ... I'll swap vacuum tubes more and more these weeks and report results if an interest acrrues.