Feel free to ask Myles

[NMBaum]

OK Myles,

I took the hint and I've stopped trying to email you with all my questions and I am now posting a question on this forum.

 

In an attempt to get rid of some of the buzziness in my Mesa Dual Rec, I replaced the stock pre-amp tube in the V1 position with a Chinese 12ax7 from Ruby Tubes. I noticed quite a difference - less buzz and more clarity and high end. The question is (drum roll) should I keep swapping out tubes? What other power tubes should I look at swapping or is the V1 the only one that makes a difference. I still run a duet of Mesa EL-34s, and they sound much better than the Mesa 6l6's. Of course, I am still contemplating your advice to have a variable bias pot put on my amp. I guess since I am low on funds, I need your advice before I start spending all my money on the elusive search for tone.

 

Thank again for all your help.

Brad (no new baby yet)

[not coaster MODERATOR]

Myles-can you tell if there is any advantage to gold plated cables vs the normal stuff?

[sgguitarzz]

Hey Myles. Thanks for the tips. I was able to pick up two of the GT 12AX7C's at Sam Ash ($14 each). I checked and the both have the round halo thing under the silver getter flash. I was amazed SA had them. I will try putting the 5751 in V1, 12AX7C in V2 & V4, and put a 12AT7 in V5 (I have an Amperex Bugle Boy and a JJ to choose from). I will switch out the V3 Brimar and replace it with a JJ 12AX7 I have. I guess we will see what happens.

 

Well I did all the above as you have suggested and had nice results. This combination of tubes did bring down the overall output - not tremendously but a noticeable amout. Depending on the tone controls settings and EQ I could get a pretty decent range of base sounds. The way I had things set up the amp had kind of a Fender vibe to which worked real well on clean and also with my various effects. I could do the early Eagles country clean thing as well as the Neil Young distortion. Pretty cool. The band liked the sound and not one person complained at all about the volume.

Thanks very much for your help.

 

Dennis

[myles_rose]

Originally posted by NMBaum:

OK Myles,

I took the hint and I've stopped trying to email you with all my questions and I am now posting a question on this forum.

 

In an attempt to get rid of some of the buzziness in my Mesa Dual Rec, I replaced the stock pre-amp tube in the V1 position with a Chinese 12ax7 from Ruby Tubes. I noticed quite a difference - less buzz and more clarity and high end. The question is (drum roll) should I keep swapping out tubes? What other power tubes should I look at swapping or is the V1 the only one that makes a difference. I still run a duet of Mesa EL-34s, and they sound much better than the Mesa 6l6's. Of course, I am still contemplating your advice to have a variable bias pot put on my amp. I guess since I am low on funds, I need your advice before I start spending all my money on the elusive search for tone.

 

Thank again for all your help.

Brad (no new baby yet)

Brad,

 

On the Ruby tube, was it a 12AX7C4? Their C4's are the selected tubes of their Chinese and are generally a bit better.

 

V1 and V2 in Mesa amps make a difference, but V1 is usually responsible for more of the initial character of the amp.

 

The problem today with preamp tubes is you have no idea what was in your amp or what you put in there. Its total chance. 12AX7's vary anywhere from -50% to +40% below and above industry spec from the 50's and 60's. At this time, the only way you can get what you might really want, is to contact Watford Valves in the U.K., and in your case, you want tubes for V1 and V2 that rate 250-260 for V2 and 220-230 for V1 which feeds V2. If V1 is too high, mush and lack of articulation results, and your volume/gain (not the master), has a range of usefulness that is very limited before it all mushes together. If too low on V1, you loose gain.

 

This is NOT the same for all Mesa products, as the non-rectifier amps have the tone control circuit pre-distortion and the rectifier series like a dual rectifier, have them post distortion, as in a Marshall amp.

 

When it comes to the power tubes, I need a LOT more info. Mesa's 6L6's can be Chinese, low grade Russian (Sovtek), high grade Russian (Svetlana), etc. Their EL-34's are much the same, and in EL-34's they also offer NOS tubes.

 

Your phase inverter has about an 80% chance of not being matched. If it does not put out the same power on the A and B side, a mis-matched output section is the result. There is a lack of sustain at certain frequencies, and the lack of lower harmonics which are cancelled out by the NFB loop will make your amp sound more thin, harsh and edgy. That is the next item you should check. If you have acess to a scope or a tech with a scope, put you amp into a load, run in a 40 cycle waveform, crank it up and look at the output. If it is not symmetrical top and bottom, then you have a mis-matched phase inverter and/or output tubes.

 

You do not need to alter your Mesa amp with an adjustible bias. Just use a higher range of tube than they offer, and you will also see on the scope, that your giant crossover notch at low levels, is gone at low levels and is just present at high levels, just where it is supposed to be when it comes to any Class A/B amp. Your amp will not be running as cool, so it will have more life, feel better dynamically, be much more touch sensitive, and loose some of the grainy quality.

 

I typically use Groove Tubes 6L6R2 (Svetlana) tubes with a rating of 7 in these amps if you are into 6L6's (which produce more massive distortion than EL-34's but with less articulation and definition). I use Groove Tubes E34Ls tubes with a rating of 6 for these amps when folks want EL-34's or EL-34R2 (svetlana again) in a range of 7 if you do not want the extra power of the E34Ls tubes.

 

These E34Ls tubes are from the JJ factory, but are just a touch different than the normal JJ tube, as GT has them make a few engineering changes under contract for them.

 

When it comes to preamp tubes, your only bet at this point if you want to really be sure, is Watford Valves in the UK. The offer what they call "balanced valves" for the phase inverter postion. If you use JJ tubes, then the 12AX7 / 12AT7 in a phase inverter slot can be supplied by Eurotubes in the USA, but they only sell the JJ tubes.

 

If you want V1 and V2 to be a known item, then you have to hit Watford Valves. Then next time, if you had a "200" and want more gain, then you can order a "230", etc. There are other factors such as rise time, but nobody I know offers those tubes other than myself, but they are for my clients - I am not a tube seller.

 

If you want a matched phase inverter, again, if its not a JJ tube, then its also Watford Valves. They also sell JJ tubes by the way.

 

For power tubes, I use Watford, Eurotubes and Groove Tubes. GT is generally my first choice as their tubes are tested dynamically rather than in a static environment. Watford also tests dynamically, but my best matches seem to come from GT when you put them on a curve tracer. I also prefer the tubes where GT rebases them with better pins than they come from the factories. The rough cadmium looking plating that you see on so many tubes is just rough enough to push old socket innards into a problem, and the smooth pins used by Groove Tubes keeps me from having to replace output sockets on amps that have tubes changed many times per year. ( I guess that is one of those aspects of GT they do not advertise or mention ).

 

I hope this was of some help.

 

Regards,

[Greazygeo]

Hey,

I have been working on a silverface Fender Twin. The vibrato is not making any sound. THe light bulb is flashing and will speed up and slow down with the controls. It seems like there are no shorted resistors or open caps. I can stop the bulb from flashing with the footswitch too. I guess I don't understand the circuit's signal flow to know where it begins and ends...The vibrato seems to want to work except i can't hear it.......any suggestions??

[snoz65]

Hi Myles and all, I have an 12AU7 that is made in Japan. There are no other markings on the tube and I was wondering what brand of tube this might be. Any ideas?

[Fols]

Myles - thanks millions - I've been lurking for the last few weeks, and have soaked up tons from your discussions. One of these weekends I need to make it down your way for one of your Saturday clinics.

I've just traded for a used Mesa Boogie Mark IV, and am thinking of retubing, but it doesn't appear to have original tubes, so I was wondering what advice you can offer for tube slots. My musical styles are predominantly classic rock, contemporary rock, with a little of everything in between, from country to pop. The tubes I'm considering, aiming for a quiet amp in the higher gain settings, smooth, but crunchy, gain (if that makes sense), not too bright, to the point of being brittle, but chimey enough, with complex harmonies, are as follows:

 

V1 (input/tone recovery stages)

Telefunken ECC83, JJ/Tesla ECC83-S, Mesa SPAX7

 

V2 (3rd gain-rhythm/5th gain-lead/FX return)

Sovtek 12AX7EH, Mullard CV4004

 

V3 (1st lead hi-gain/reverb return)

??? 12AT7, Sylvania ECC83/12AX7, Mullard ECC83

 

V4 (2nd lead hi gain/reverb send)

Phillips NOS JAN 12AT7WC, ??? 5751, Sovtek 12AX7EH

 

V5 (Phase Inverter:

GE NOS JAN 12AT7WC, RCA 12AT7, or RCA 5751

 

I'd be interested in hearing what you (or anyone else, for that matter) has to offer for discussion on these choices. Most of the selection is based on internet research, and not actual tone tests, other than the Sovtek 12AX7EH's which I liked the tone of, but had a little trouble with hissing in higher gain settings, as well as the lead tones were somewhat grainy.

 

The amp currently has GrooveTube GT6L6S (4's), and Mesa 12AX7-A/ECC83's in it. the Groove Tubes are replacemetns, I'm sure, but the 12AX7's may be originals. the amp appears to be about a 1992 vintage, but I haven't confirmed the serial # dating, yet (anyone know a website to check date of Mesa's, based on serial #'s, BTW?)

 

Thanks again for all your help - I've learned more here in the last few weeks than the last couple of years!

[myles_rose]

Originally posted by Cereal:

Myles-can you tell if there is any advantage to gold plated cables vs the normal stuff?

Cereal,

 

Gold is a very good conductor and does not corrode.

 

Regards,

[myles_rose]

Originally posted by sgguitarzz:

Hey Myles. Thanks for the tips. I was able to pick up two of the GT 12AX7C's at Sam Ash ($14 each). I checked and the both have the round halo thing under the silver getter flash. I was amazed SA had them. I will try putting the 5751 in V1, 12AX7C in V2 & V4, and put a 12AT7 in V5 (I have an Amperex Bugle Boy and a JJ to choose from). I will switch out the V3 Brimar and replace it with a JJ 12AX7 I have. I guess we will see what happens.

 

Dennis,

 

Sometimes you hear a bigger change, and sometimes a smaller one. Its because the characteristics of the tubes are so inconsistant.

 

Watford Valves has "graded" preamp tubes, and from what I hear, Groove Tubes is about to offer this also on a limited basis, but you may have to order them directly from GT. I also think they will have matched phase inverters but will have a few more twists over some other tubes.

 

Regards,

 

Well I did all the above as you have suggested and had nice results. This combination of tubes did bring down the overall output - not tremendously but a noticeable amout. Depending on the tone controls settings and EQ I could get a pretty decent range of base sounds. The way I had things set up the amp had kind of a Fender vibe to which worked real well on clean and also with my various effects. I could do the early Eagles country clean thing as well as the Neil Young distortion. Pretty cool. The band liked the sound and not one person complained at all about the volume.

Thanks very much for your help.

 

Dennis

[myles_rose]

Originally posted by Greazygeo:

Hey,

I have been working on a silverface Fender Twin. The vibrato is not making any sound. THe light bulb is flashing and will speed up and slow down with the controls. It seems like there are no shorted resistors or open caps. I can stop the bulb from flashing with the footswitch too. I guess I don't understand the circuit's signal flow to know where it begins and ends...The vibrato seems to want to work except i can't hear it.......any suggestions??

Greazygeo,

 

Have you changed the preamp tube?

 

If that does not help, its time to look at it with a meter and scope.

 

Regards,

[myles_rose]

Originally posted by snoz65:

Hi Myles and all, I have an 12AU7 that is made in Japan. There are no other markings on the tube and I was wondering what brand of tube this might be. Any ideas?

snoz65,

 

Its hard to tell without seeing the tube, but I do not know of any Japanese manufactured tubes. It was probably OEM'd from China or Europe and silkscreened with a Japanese name or logo.

 

Regards,

[Greazygeo]

Originally posted by myles111:

Originally posted by Greazygeo:

Hey,

I have been working on a silverface Fender Twin. The vibrato is not making any sound. THe light bulb is flashing and will speed up and slow down with the controls. It seems like there are no shorted resistors or open caps. I can stop the bulb from flashing with the footswitch too. I guess I don't understand the circuit's signal flow to know where it begins and ends...The vibrato seems to want to work except i can't hear it.......any suggestions??

Greazygeo,

 

Have you changed the preamp tube?

 

Did that first.....no difference. This is the 100 watt twin w master volume, no mods or anything changed either. Where does the circuit actually start and end?? It looks like it feeds in at the 220 K mixing resistors......thanks for any help.......

 

If that does not help, its time to look at it with a meter and scope.

 

Regards,

[myles_rose]

Originally posted by Fols:

Myles - thanks millions - I've been lurking for the last few weeks, and have soaked up tons from your discussions. One of these weekends I need to make it down your way for one of your Saturday clinics.

I've just traded for a used Mesa Boogie Mark IV, and am thinking of retubing, but it doesn't appear to have original tubes, so I was wondering what advice you can offer for tube slots. My musical styles are predominantly classic rock, contemporary rock, with a little of everything in between, from country to pop. The tubes I'm considering, aiming for a quiet amp in the higher gain settings, smooth, but crunchy, gain (if that makes sense), not too bright, to the point of being brittle, but chimey enough, with complex harmonies, are as follows:

 

V1 (input/tone recovery stages)

Telefunken ECC83, JJ/Tesla ECC83-S, Mesa SPAX7

 

V2 (3rd gain-rhythm/5th gain-lead/FX return)

Sovtek 12AX7EH, Mullard CV4004

 

V3 (1st lead hi-gain/reverb return)

??? 12AT7, Sylvania ECC83/12AX7, Mullard ECC83

 

V4 (2nd lead hi gain/reverb send)

Phillips NOS JAN 12AT7WC, ??? 5751, Sovtek 12AX7EH

 

V5 (Phase Inverter:

GE NOS JAN 12AT7WC, RCA 12AT7, or RCA 5751

 

I'd be interested in hearing what you (or anyone else, for that matter) has to offer for discussion on these choices. Most of the selection is based on internet research, and not actual tone tests, other than the Sovtek 12AX7EH's which I liked the tone of, but had a little trouble with hissing in higher gain settings, as well as the lead tones were somewhat grainy.

 

The amp currently has GrooveTube GT6L6S (4's), and Mesa 12AX7-A/ECC83's in it. the Groove Tubes are replacemetns, I'm sure, but the 12AX7's may be originals. the amp appears to be about a 1992 vintage, but I haven't confirmed the serial # dating, yet (anyone know a website to check date of Mesa's, based on serial #'s, BTW?)

 

Thanks again for all your help - I've learned more here in the last few weeks than the last couple of years!

Fols,

 

The next clinic is this Saturday 5/11. If you can't make it for this one, there will be another in two or three weeks.

 

Mesa Mk IV's have been around for a bit of time now, so it does not surprise me that it does not have the original tubes.

 

On your amp, you can do many styles as their gain structure is pretty versitile. Because of the cascading gain structure, and because the tone controls are pre distortion rather than post distortion, I like lower gain 12AX7 in V1 of those amps. That way they are clean and quiet in the cleaner settings.

 

V1 (input/tone recovery stages)

Telefunken ECC83, JJ/Tesla ECC83-S, Mesa SPAX7

 

These are all very different sounding tubes. The current Mesa SPAX7 is the Electro Harmonix tube. The JJ and Telefunkens are a bit different, with the JJ having a bit more of an extended mid and mid high range. This is going to be personal preference, but I'd opt for a tube that is a bit lower in gain than average for any of the chosen types. I normally use tubes with my rating of about 80 in that position.

 

V2 (3rd gain-rhythm/5th gain-lead/FX return)

Sovtek 12AX7EH, Mullard CV4004

 

Id save your money here, and go with the EH.

 

V3 (1st lead hi-gain/reverb return)

??? 12AT7, Sylvania ECC83/12AX7, Mullard ECC83

 

You should try the 12AT7 and a 12AX7 here, and see what you prefer. Of the 12AX7's, this is personal preference.

 

V4 (2nd lead hi gain/reverb send)

Phillips NOS JAN 12AT7WC, ??? 5751, Sovtek 12AX7EH

 

I like 12AT7's here as they have more current drive for the reverb send than a 12AX7, even with less gain.

 

V5 (Phase Inverter:

GE NOS JAN 12AT7WC, RCA 12AT7, or RCA 5751

 

Again, I prefer AT7's in phase inverter positions, but make sure it is balanced on the A and B sides.

 

Any tube with higher gain, especially in a Mark amp, will have more background noise. That is why I prefer one with a lower initial gain, as its noise will be amplified throughout the rest of the signal chain.

 

You may want to contact Kelly or Rick over at Groove Tubes, as they are in the process of having some hand selected tubes. Maybe they can get you what I call an "80" or what Watford Valves would call a "200". You can call them at 818-361-4500. Its worth a try.

 

The 6L6S is a JJ tube that Groove Tubes rebases and uses a nicer base and better quality pins. The 4 rating is too cold for your amp though, and if you go up to a 7 rating, you will lose a lot of the grain and gravelly sound you hear a bit, especially in the cleaner settings.

 

You're more than welcome.

 

Regards,

[myles_rose]

Originally posted by Greazygeo:

Originally posted by myles111:

Originally posted by Greazygeo:

Hey,

I have been working on a silverface Fender Twin. The vibrato is not making any sound. THe light bulb is flashing and will speed up and slow down with the controls. It seems like there are no shorted resistors or open caps. I can stop the bulb from flashing with the footswitch too. I guess I don't understand the circuit's signal flow to know where it begins and ends...The vibrato seems to want to work except i can't hear it.......any suggestions??

Greazygeo,

 

Have you changed the preamp tube?

 

Did that first.....no difference. This is the 100 watt twin w master volume, no mods or anything changed either. Where does the circuit actually start and end?? It looks like it feeds in at the 220 K mixing resistors......thanks for any help.......

 

If that does not help, its time to look at it with a meter and scope.

 

Regards,

What you need to do is an interference test where with the prints, you start at end back of the circuit and work forward listening to the pops increase in volume. When the pop stops, there is the problem.

 

Regards,

[MikeS_dup1]

Myles,

 

I have a couple of questions regarding 6L6's. First, are 6CL6 tubes the same as 6L6's? And if they are, would $25 for a set of five NIB JAN/GE be a good price? I would image if they are 6L6's $25 would be a great price. I guess it would be a crapshoot if 2 or more were matched.

 

Thanks,

 

MikeS

[AgentOrange]

Yo miles, this is James from the HC Forum

 

First off, upon recommendation from Watford Valves over here in the UK (i noticed you have a link to them on your page), I have ordered two Harma 6L6s which they plugged over all the other stuff they have. How do you think they will affect my sound if all other things are kept constant? Well onto the real question......

 

If i wanted a tighter more focused sound from my rectoverb, would this be possible/worth the money, in terms of an audible difference, by changing the preamp valves. If so, what valves would you recommend? I have 5 12AX7s in there all MESA tubes so id unno what they were b4

any help would be greatly appreciated

 

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

[myles_rose]

Originally posted by MikeS:

Myles,

 

I have a couple of questions regarding 6L6's. First, are 6CL6 tubes the same as 6L6's? And if they are, would $25 for a set of five NIB JAN/GE be a good price? I would image if they are 6L6's $25 would be a great price. I guess it would be a crapshoot if 2 or more were matched.

 

Thanks,

 

MikeS

Mike,

 

Stay away from those, they are very different.

 

They do not even share the same pinout at as 6L6, and there are other differences too.

 

Regards,

[myles_rose]

Originally posted by AgentOrange:

Yo miles, this is James from the HC Forum

 

If i wanted a tighter more focused sound from my rectoverb, would this be possible/worth the money, in terms of an audible difference, by changing the preamp valves. If so, what valves would you recommend? I have 5 12AX7s in there all MESA tubes so id unno what they were b4

any help would be greatly appreciated

 

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

AgentOrange,

 

Your are in the right part of the globe, as you have Watford Valves in your own backyard.

 

You want to do a few things:

 

1. Replace V1 with one of their 12AX7's with a rating of about 225 on their scale.

 

2. Replace V2 with one of their 12AX7's with about a 200 rating on their scale.

 

These first two changes will allow a much wide usable range between your volume (gain) and master and will get rid of a lot of the smudge that comes in at gain settings over 3-4.

 

3. Replace your phase inverter with one of the Watford "balanced valves". If you want more clean headroom, use one of their 12AT7's and for more gain use a 12AX7. This is personal taste. In the phase inverter position, you don't have to spend a lot of money, as we are looking at current drive here, not tone shaping.

 

On the V1 and V2 tubes, expensive NOS tubes are not really as noticible in these amps, as their circuits are designed for a different type of response than the vintage curcuits of the older tweed a blackface amps that had way less than 200 volts on their plates.

 

Regards,

[villainvomit]

Myles,

 

First let me say thanks for sharing all the tube info so freely.

 

Secondly, here is a lightweight question for you. Have you ever run across Korean 12ax7's and if so what do you think about them. I wouldn't think there would be too many manufacturers in that local. They were in a second hand '78 JMP 100 watt I purchased months ago (also had JJ E34L's which I have recently bought more of). No markings on the 12ax7's except 12ax7 and made in Korea.

 

Any thoughts?

 

Thanks again,

VV

[myles_rose]

Originally posted by villainvomit:

Myles,

 

First let me say thanks for sharing all the tube info so freely.

 

Secondly, here is a lightweight question for you. Have you ever run across Korean 12ax7's and if so what do you think about them. I wouldn't think there would be too many manufacturers in that local. They were in a second hand '78 JMP 100 watt I purchased months ago (also had JJ E34L's which I have recently bought more of). No markings on the 12ax7's except 12ax7 and made in Korea.

 

Any thoughts?

 

Thanks again,

VV

villainvomit,

 

A free beer for you at an amp clinic! You stumpped me on on this one for sure! I did not even know there were any tube factories in Korea!

 

On your Marshall though, check the bias, as somebody may have plugged in the JJ's without re-biasing, and they have about a 15% different bias requirement than 25 watt EL-34 tubes.

 

If you're in my area (Los Angeles) drop me a line and I will check this for you gratis, and if necessary, I will also adjust it for free since you stumpped me

 

Regards,

[overcomer]

hi, i the new 6L6ge's from rick on monday, and he said you were"in the building" at the time. anyway, i told him about what you had said that "get some matched 12aT7's" to which he replied "you dont have to match preamp tubes" i was unable to explain what i meant. i ordered two 12at7s from him also to retube my super reverb. iwant to spend the right money on it now and get it fixed up so i wont have to spend any later. I think maybe i see now that what you meant was to get some balanced phase inverter tubes from watford or another place. right? well, thanks again for you replies,,

[MikeS_dup1]

Thanks Myles I had my doubts.

 

MikeS

[Dave M]

Hi Myles (visiting from Harmony Central)

 

I have a Boogie 50/50 power amp and would like to check with you that I'm using the correctly rated (?) valves. I'm currently using Harma STR 6L6GC valves (30 MA, 3.1M/AV) as supplied by Watford Valves. How would these compare to Mesa Boogie 'branded' valves. i.e. what colour rating would they equal.

 

The guy that serviced my amp set he could not change the bias of my power amp. Is this correct ?

 

I am asking all this as I only seem to go 5-6 months without a tube going bad. Would failing capacitors cause premature valve failure ?

 

Any help would be appreciated.

 

Thanks

Dave

[villainvomit]

Originally posted by myles111:

[qb]Myles,

 

A free beer for you at an amp clinic! You stumpped me on on this one for sure! I did not even know there were any tube factories in Korea!

 

On your Marshall though, check the bias, as somebody may have plugged in the JJ's without re-biasing, and they have about a 15% different bias requirement than 25 watt EL-34 tubes.

 

If you're in my area (Los Angeles) drop me a line and I will check this for you gratis, and if necessary, I will also adjust it for free since you stumpped me

 

Regards,

Myles,

 

Yes sir, I will get the bias checked, as this amp sounds better than any I have or have played through. It might sound even better, huh?

 

I live in Atlanta, but you can bet I will look you up next time I am in your area. Hell, I might even drive to LA the next time I am in Vegas (not quite the same as it used to be, but still fun).

 

With much appreciation,

 

VV

[Henrionov]

Hey Myles, thanks for all the excellent advise. I have been reading your many posts and have learned a lot.

I have a couple of old Fender amps I'm thinking of taking down to your free amp clinic this weekend and am wondering what to expect. I won't be able to make to until about 3pm. Will there be a line, 20 guys long waiting for amp checkups? How long do you spend with each amp? I'll be driving about an hour and don't want to endure a total zoo, but I would love to have my amps checked out.

Thanks in advance, and keep up the great work!

[myles_rose]

Originally posted by overcomer:

hi, i the new 6L6ge's from rick on monday, and he said you were"in the building" at the time. anyway, i told him about what you had said that "get some matched 12aT7's" to which he replied "you dont have to match preamp tubes" i was unable to explain what i meant. i ordered two 12at7s from him also to retube my super reverb. iwant to spend the right money on it now and get it fixed up so i wont have to spend any later. I think maybe i see now that what you meant was to get some balanced phase inverter tubes from watford or another place. right? well, thanks again for you replies,,

overcomer,

 

Groove Tubes and I am now working together to hand select so tubes that I might call something like "Ultra" or who knows what (open to suggestions). Its not a product of their's yet, and if it ever becomes a product, it will be in very short supply, as I have to go through 20-50 tubes to get one that is matched. If you are a friend or Ricks or a relation of GT, let Rick know to contact me, and I will find you some matched 12AT7s. I think they will be about $25 rather than the normal $18 due to the extra searching around and testing each one by hand.

 

Regards,

[myles_rose]

Originally posted by Dave M:

Hi Myles (visiting from Harmony Central)

 

I have a Boogie 50/50 power amp and would like to check with you that I'm using the correctly rated (?) valves. I'm currently using Harma STR 6L6GC valves (30 MA, 3.1M/AV) as supplied by Watford Valves. How would these compare to Mesa Boogie 'branded' valves. i.e. what colour rating would they equal.

 

The guy that serviced my amp set he could not change the bias of my power amp. Is this correct ?

 

I am asking all this as I only seem to go 5-6 months without a tube going bad. Would failing capacitors cause premature valve failure ?

 

Any help would be appreciated.

 

Thanks

Dave

Dave,

 

I need to know at what B+ voltage Watford came up with the 30mA figure.

 

If this a "mid-range" tube for them, they would be fine in your Mesa without a bias adjustment. You can also ask them how their rating would covert to a Groove Tubes rating. If it is in GT 4-7 rating, you would be fine.

 

To convert fro GT to Mesa ratings, there is a table and a writeup on my website.

 

Regards,

[myles_rose]

Originally posted by villainvomit:

Originally posted by myles111:

[qb]Myles,

 

A free beer for you at an amp clinic! You stumpped me on on this one for sure! I did not even know there were any tube factories in Korea!

 

On your Marshall though, check the bias, as somebody may have plugged in the JJ's without re-biasing, and they have about a 15% different bias requirement than 25 watt EL-34 tubes.

 

If you're in my area (Los Angeles) drop me a line and I will check this for you gratis, and if necessary, I will also adjust it for free since you stumpped me

 

Regards,

Myles,

 

Yes sir, I will get the bias checked, as this amp sounds better than any I have or have played through. It might sound even better, huh?

 

I live in Atlanta, but you can bet I will look you up next time I am in your area. Hell, I might even drive to LA the next time I am in Vegas (not quite the same as it used to be, but still fun).

 

With much appreciation,

 

VV

Next time you are going to Vegas, drop me a note. Maybe I'll meet you there, and we can look at your amp(s) and then hit the casinos.

 

Regards,

[myles_rose]

Originally posted by Henrionov:

Hey Myles, thanks for all the excellent advise. I have been reading your many posts and have learned a lot.

I have a couple of old Fender amps I'm thinking of taking down to your free amp clinic this weekend and am wondering what to expect. I won't be able to make to until about 3pm. Will there be a line, 20 guys long waiting for amp checkups? How long do you spend with each amp? I'll be driving about an hour and don't want to endure a total zoo, but I would love to have my amps checked out.

Thanks in advance, and keep up the great work!

Henrionov,

 

This weekend will probably be a quiet one as I have not sent out my mailing to the folks I know, so they have not also told their friends.

 

Just try to come about 12-1, and it will be slower than later in the afternoon. If you tell me you had a drive, then if there is a line, you will go to the front. There is normally not a wait, maybe 1 amp in front of anybody else at the most, and it goes pretty fast with plenty of time for questions.

 

Its normally goes pretty smoothly.

 

Regards,

[boldo]

hi myles I've read your article 'bout tubes but I'd like to ask you some specific advice.I own a marshall jtm 612 I've got svet el34 as power tubes.I got a 12at7 as ph.inv. and It works great. Now I just want to find the right tubes for pos v1 and v2 : I want the best performance in clean-going-distorted situations , lots of sustain , clarity and "fullness" - a nice blues-rock tone.I mostly use the boost channel to get my best tone , expecially at reasonable (doesn't mean very low, just not eazr splitting) volumes. A thing that I really hate about stock tubes is that they get nasal and a bit "boxy-and-dark-sounding" when pushed hard with a stompbox.I play a strat, mostly in the neck position.