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  #16  
Old 04-17-2017, 09:00 AM
Steve DeRosa Steve DeRosa is offline
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Originally Posted by KevWind View Post
...And speaking of the" lingo" does anyone here know what "cathode-biased" means? And also is there such thing as expected normal tube life ???
Answer to question #1:

https://en.wikipedia.org/wiki/Cathode_bias
http://carlscustomamps.com/cathode-vs-fixed-bias/

Answer to question #2:
Depends on how hard, how often, and how long (at a given stretch) you play, as well as the particular circuit/position in which the tubes are being used - and, of course, the quality of the tubes themselves. I've heard tell of owners of McIntosh audio gear from the late-50's who are still running the original tubes (mostly in the lower-stress preamp and rectifier positions, but there are still a select few who have the OEM power tubes); in the guitar-amp world, Dennis Kager told me that a number of the older cathode-bias Ampegs (particularly the top-panel Jet/Rocket) were so conservatively designed (in terms of the voltages applied to the tubes) that it wasn't uncommon for well-maintained examples from the early-60's to still have their original tubes, and still with plenty of life left. On the other hand, if you're in a Deep Purple tribute band and running your '71 200W Marshall Major full-tilt every night (something every guitarist should add to his/her bucket list, BTW: the musical equivalent of strapping into a Top Fuel dragster and laying down a 330 MPH pass - and the justly-revered 100W Plexi doesn't even come close), you'll probably be replacing those big old KT88 power tubes every 4-6 months (at considerable expense), the preamp tubes at least once a year. Practically speaking, you know your own playing habits, and your ear is good enough to know when your amp no longer has the "it" factor that brought a big smile to your face the first time you plugged in - aside from obvious hums/hisses/crackles, that's usually the signal that a tube replacement might be in order...

Corollary to questions #1 & 2:
If you're considering a retube job - or even if you just want to learn a little bit of the tubehead jargon - don't do anything until you've visited these folks:

http://www.thetubestore.com/

Wonderful customer service, extremely knowledgeable (read some of their in-depth tube reviews), very easy to deal with, fast shipping - they've been my source for several years and I can't recommend them highly enough; call/e-mail them and tell them exactly what your tonal requirements are (or ask for recommendations) - they'll be more than glad to help you assemble a tube package that meets (or exceeds) your needs...
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  #17  
Old 04-17-2017, 09:55 AM
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Originally Posted by Steve DeRosa View Post
Answer to question #1:

https://en.wikipedia.org/wiki/Cathode_bias
http://carlscustomamps.com/cathode-vs-fixed-bias/

Answer to question #2:
Depends on how hard, how often, and how long (at a given stretch) you play, as well as the particular circuit/position in which the tubes are being used - and, of course, the quality of the tubes themselves. I've heard tell of owners of McIntosh audio gear from the late-50's who are still running the original tubes (mostly in the lower-stress preamp and rectifier positions, but there are still a select few who have the OEM power tubes); in the guitar-amp world, Dennis Kager told me that a number of the older cathode-bias Ampegs (particularly the top-panel Jet/Rocket) were so conservatively designed (in terms of the voltages applied to the tubes) that it wasn't uncommon for well-maintained examples from the early-60's to still have their original tubes, and still with plenty of life left. On the other hand, if you're in a Deep Purple tribute band and running your '71 200W Marshall Major full-tilt every night (something every guitarist should add to his/her bucket list, BTW: the musical equivalent of strapping into a Top Fuel dragster and laying down a 330 MPH pass - and the justly-revered 100W Plexi doesn't even come close), you'll probably be replacing those big old KT88 power tubes every 4-6 months (at considerable expense), the preamp tubes at least once a year. Practically speaking, you know your own playing habits, and your ear is good enough to know when your amp no longer has the "it" factor that brought a big smile to your face the first time you plugged in - aside from obvious hums/hisses/crackles, that's usually the signal that a tube replacement might be in order...

Corollary to questions #1 & 2:
If you're considering a retube job - or even if you just want to learn a little bit of the tubehead jargon - don't do anything until you've visited these folks:

http://www.thetubestore.com/

Wonderful customer service, extremely knowledgeable (read some of their in-depth tube reviews), very easy to deal with, fast shipping - they've been my source for several years and I can't recommend them highly enough; call/e-mail them and tell them exactly what your tonal requirements are (or ask for recommendations) - they'll be more than glad to help you assemble a tube package that meets (or exceeds) your needs...
Hey. Thanks a bunch. So from the wiki article cathode biased is also called self biased, so I'm guessing. If or when I might decide to re-tube I won't have to worry about setting bias ?

I do know what you mean about Macintosh and apparent the tube life. In the 70,s the three main high end amps we sold the most of were Macintosh, Phase Linear ,and then Carver ( when Phase Linear was bought by Pioneer and Bob Carver started Caver ). And the subject of changing tubes in the Macintosh was never discussed and something I never thought about really.
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Last edited by KevWind; 04-17-2017 at 03:18 PM.
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  #18  
Old 04-17-2017, 01:01 PM
muscmp muscmp is offline
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kev: i have several 60s amps that are still running their original output tubes. i've purposely rolled the preamp tubes for my liking tho.

i also have a couple of 60s dynaco st70s with original output tubes.

play music!
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  #19  
Old 04-18-2017, 07:00 AM
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Originally Posted by muscmp View Post
kev: i have several 60s amps that are still running their original output tubes. i've purposely rolled the preamp tubes for my liking tho.

i also have a couple of 60s dynaco st70s with original output tubes.

play music!
Hey good to know. Except what does "rolled" mean, replaced I am guessing yes ? You experienced guys have now made me curious I suppose I will have to look and see If I can find out the mfg of the tubes in my Titan
Just for the sake of learning if nothing else
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  #20  
Old 04-18-2017, 09:56 AM
Steve DeRosa Steve DeRosa is offline
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Originally Posted by KevWind View Post
...You experienced guys have now made me curious. I suppose I will have to look and see if I can find out the mfg of the tubes in my Titan just for the sake of learning if nothing else...
FYI some companies have their tubes stamped with their brand - as they have for years - and unless you know how to read some of the codes on the bottles (I don't) you're not going to get any useful data. What I can say with reasonable certainty is that Fender uses Russian preamp tubes (comparable to the Groove Tubes 12AX7-R) and Slovakian EL84 power tubes (similar to some of the JJ/EH/Groove Tubes offerings), both stamped with the Fender logo, and that Bugera's proprietary tubes are made by Shuguang (who TMK also supplies tubes for other amp companies producing in China - Vox, Marshall, VHT, etc.); it's an educated guess on my part, but given the tight, clean response of your Titan I'm thinking that Supro sources their tubes from Russia or Eastern Europe - you might want to contact the company for more info. In the meantime, if you're looking to learn what a tube swap can do for your amp you might find these of interest:

http://www.thetubestore.com/Resource...7-Tube-Reviews
http://www.thetubestore.com/Tubes/12...C81-Tube-Types
http://www.thetubestore.com/Resource...6-Tube-Reviews

You'll see the designation JAN, meaning Joint Army-Navy, preceding the manufacturer's name (GE, RCA, Sylvania, Philips, etc.) on some of these tubes. FYI these are the US/NATO-manufactured surplus mil-spec tubes that the hardcore Fender guys would sell their gonads to get, and if you're willing to pay the price they're arguably the most durable tubes on the market; good news is that there's also some old Soviet-bloc military stuff out there, equally rugged and usually far cheaper (I'm running these in both my Bugeras, BTW) - read some of the reviews/specs, I think you'll find it enlightening...
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  #21  
Old 04-18-2017, 04:17 PM
muscmp muscmp is offline
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Originally Posted by KevWind View Post
Hey good to know. Except what does "rolled" mean, replaced I am guessing yes ? You experienced guys have now made me curious I suppose I will have to look and see If I can find out the mfg of the tubes in my Titan
Just for the sake of learning if nothing else
kev: rolled means to try various preamp tubes to see if you like one better than the other. you could try rca, zenith, ge, etc. you could also try 12ay7 instead of a 12ax7 also. that would give you less gain and more clean headroom. as with everything on the agf, it is all subjective.

if your amp is open backed, you should able to see all of the tubes and their brands.

play music!
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  #22  
Old 04-18-2017, 06:30 PM
Steve DeRosa Steve DeRosa is offline
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Originally Posted by muscmp View Post
Kev: rolled means to try various preamp tubes to see if you like one better than the other. You could try RCA, Zenith, GE, etc. you could also try 12AY7 instead of a 12AX7 also. That would give you less gain and more clean headroom. As with everything on the AGF, it is all subjective...
From thetubestore.com website:

Quote:
Choosing Preamp Tubes by Gain Factor

One simple tweak that is favored by guitar amp users is to plug in a pre-amp tube with a slightly different gain factor. (Important: this only works for tubes that are pinout and plate voltage compatible, such as the six types listed below.)

The gain factor of a tube simply measures how much it amplifies the input signal. For example, the common 12AX7 tube has a gain factor of 100, while a 5751 tube (which is often used in place of a 12AX7) has a gain factor of 70. This means that if you plug a 5751 into a socket that expects a 12AX7, the pre-amp will have about 30% less gain. Not only will this make the amp quieter, but it can also alter the sound by making the power section work harder when you turn it up. Many guitar amp users (particularly harmonica players) like to reduce the gain to get a different sound or calm the amp down to prevent feedback.

In some cases, you can also go the other way and increase the gain factor. It is generally more risky to increase the gain factor rather than decrease it, as the added gain may be too much for the rest of the amplifier circuit. An example of an acceptable up-swap can be found in Fender amps that use a 12AT7 (with a gain factor of 60) as a "reverb driver" tube. You can sub in a 5751 to increase the gain by just a touch.

The tubes we list here also have several alternate names, which we list below. Note that the alternates do not have significantly different gain factors; they are simply a different name for the same thing.
  • 12AX7 (Gain Factor 100) - ECC83, CV4004, 7025, ECC803, E83CC, 6681
  • 5751 (Gain Factor 70) - no alternate name; substitute for 12AX7 (but not vice versa), 12AT7
  • 12AT7 (Gain Factor 60) - ECC81, 6201, 6679
  • 12AY7 (Gain Factor 45) - 6072
  • 12AV7 (Gain Factor 41) - 5965
  • 12AU7 (Gain Factor 19) - ECC82, 5963, 5814, 6189
Before you discover the new possibilities in your amp, let us give a disclaimer. Your amp was originally designed for a certain type, and although tube amps are often forgiving, it may not have a tone that you like with a different tube type. For instance, changing the tube type doesn't only change the gain factor; there are other variables as well, and your amp may have a circuit that is more particular than others. As a general rule, the substitutions we describe here should work well but there are exceptions, and we don't warranty any problems that result from trying mismatched tube types. For the best results, find other people on the net who have experience swapping tubes with the amp you use...

These substitutions can also work in home audio amps, but we don't recommend trying this unless you are having trouble finding the correct tube type for your amp.
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  #23  
Old 04-19-2017, 01:14 PM
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Quote:
Originally Posted by muscmp View Post
kev: rolled means to try various preamp tubes to see if you like one better than the other. you could try rca, zenith, ge, etc. you could also try 12ay7 instead of a 12ax7 also. that would give you less gain and more clean headroom. as with everything on the agf, it is all subjective.

if your amp is open backed, you should able to see all of the tubes and their brands.

play music!
Quote:
Originally Posted by Steve DeRosa View Post
From thetubestore.com website:
where would I be without yous guys ( besides playin' instead of jabberin' )
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  #24  
Old 04-19-2017, 11:43 PM
maxtheaxe maxtheaxe is offline
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Quote:
Originally Posted by muscmp View Post
if your amp is open backed, you should able to see all of the tubes and their brands.
These amps are open-backed...sort of...but these little guys are really crowded in there and the tubes are enclosed in a mesh grill and arranged such that you really can't see the details of them without taking stuff apart.

I looked at the Tubestore's pages with re-tube kits for specific amps, hoping there might be some info for Supro...they have quite a few amps in there and I expect that the Supros will show up in there sooner or later, but for now...no Supros. Incidentally, that's a real eye-opener, seeing the prices of the various tubes sets, with some of their "Ultimate" re-tube packages selling in the neighborhood of $600.00 or more! Some of those amps don't even cost that much (but maybe that's why...?).

With what little I do know of tube characteristics, my guess is gonna be something along the lines of Phillips or similar....USA mil-spec?
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  #25  
Old 04-20-2017, 09:01 AM
Steve DeRosa Steve DeRosa is offline
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Originally Posted by maxtheaxe View Post
...I looked at the Tubestore's pages with re-tube kits for specific amps...Incidentally, that's a real eye-opener, seeing the prices of the various tubes sets, with some of their "Ultimate" re-tube packages selling in the neighborhood of $600.00 or more! Some of those amps don't even cost that much (but maybe that's why...?).

With what little I do know of tube characteristics, my guess is gonna be something along the lines of Phillips or similar...USA mil-spec?
Practically speaking, those "Ultimate" and "Vintage" packages are for the restorers/collectors - the guys who have the dead-mint '64 Twin Reverb with the original (also dead-mint) cover, or the gold-logo Marshall that hasn't seen the light of day since Monterey - and want/need period-accurate tubes for their museum-quality equipment; IME the "Premium" packages offer the best performance-per-dollar for guys like us, whose amps are regularly used but not abused - "Value" packages are for the CL/eBay "flippers" ("Marshall DSL40 1x12" combo for sale - great condition, all new tubes"), a step or two up from made-in-China OEM but that's about it...

FYI JAN (US mil-spec) tubes are a scarce commodity and becoming increasingly so - hence the elevated prices on the most popular types (12AX7, 6L6, 5AR4, etc.) - and although a few boutique builders use them it wouldn't be practical for a mass manufacturer like Supro. As I said earlier, I'm thinking they source theirs from either Russia (most likely IMO) or Eastern Europe (Slovakia, Poland, Czech Republic): supply is plentiful, prices are reasonable, and they're durable enough to handle running Class-A @ 50W output - conditions that would result in certain failure for lesser tubes...
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  #26  
Old 04-21-2017, 03:50 PM
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even tho i don't own a supro, i thought i'd find out what tubes they use for those who do. this is from supro's david koltai:

We use:

JJ brand for all preamp tubes
JJ brand for all 6V6 power tubes (Supreme amp)
Sovtek brand for 5881 / 6L6WGC power tubes (Royal Reverb / Coronado / Comet / Thunderbolt / Rhythm Master)
EHX brand for 6973 power tubes (Dual-Tone / Tremo-verb / Black Magick / Neptune / Saturn)

ALL TUBES are tested and matched in house at Supro factory in NY

best

David Koltai

play music!
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  #27  
Old 04-21-2017, 04:52 PM
Steve DeRosa Steve DeRosa is offline
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Originally Posted by muscmp View Post
Even tho i don't own a Supro, i thought i'd find out what tubes they use for those who do. This is from Supro's David Koltai:

We use...Sovtek brand for 5881/6L6WGC power tubes (Royal Reverb/Coronado/Comet/Thunderbolt/Rhythm Master)...

ALL TUBES are tested and matched in house at Supro factory in NY...
Reviews from thetubestore.com website:
Quote:
Sovtek 5881WXT - Solid construction and good performance. While not outstanding, the 5881WXT is probably the most commonly used tube of its type. Many amp manufacturers have been using these reliable workhorses as original equipment components. A good choice for general purpose use but not as rich in harmonic content as others in this class. If you like to run your guitar straight into the amp, there are better choices. If you prefer to run through a bunch of rack equipment or like major crunch and overdrive sounds then this tube will work well.
Quote:
Sovtek 6L6WXT+ - Guitar-cable-amplifier. If this describes the rig you use, then this is one of two modern tubes you should consider. This is not a repackaged 5881. Extremely low noise and a lack of microphonics combine with excellent ratings for detail and harmonic content to provide a tube of exceptional quality. These tubes can be used in any tube amp. Plenty of power and great tone. We have tested these tubes with plate voltages ranging from 425 to 500 volts without problem. Biasing can be set from conservative to hot; again, no real problem and great tone will be delivered from most settings.
I figured they'd need a Russian tube in this application; since there's no listing for the Titan - and given that it was intended as a high-power/ultra-clean amp in a small box - I'd say they're using the latter...
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Old 04-22-2017, 12:24 AM
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Interesting...looking further for myself, I ran across this page, which I had not seen before;

https://suprousa.com/tech/power-amps/

This lists the tubes used in various Supro amps and tells a little bit about why. One thing I noticed was that the TremoVerb, which is identical to the Titan except for the power rating of 25 watts, uses the EHX 6973 power tubes, while the 50 watt Titan uses the Sovtek 6L6.

Thanks to Steve DeRosa and muscmp for teasing these details out.
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  #29  
Old 04-22-2017, 07:06 AM
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Originally Posted by maxtheaxe View Post
Interesting...looking further for myself, I ran across this page, which I had not seen before;

https://suprousa.com/tech/power-amps/

This lists the tubes used in various Supro amps and tells a little bit about why. One thing I noticed was that the TremoVerb, which is identical to the Titan except for the power rating of 25 watts, uses the EHX 6973 power tubes, while the 50 watt Titan uses the Sovtek 6L6.

Thanks to Steve DeRosa and muscmp for teasing these details out.
Hey thanks for that link and again thanks to all Guess for now I will not contemplate tubes but rather focus on the major and minor pentatonic scale patterns up and down the neck and not getting lost while ripping a lead
Guess neither Clapton, Knopfler, nor Santana are in danger of being deposed quite yet
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  #30  
Old 04-29-2017, 02:31 PM
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Congrats on your NAD!
I love Supros, and Tone Kings, and Carrs, and too many to list,,,.
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