Feel free to ask Myles

[hechtdavid]

Hi Myles,

 

I just ordered a matched quad of the GT 6L6GE's for my 1999 "Evil" Twin and was wondering if I should replace the phase invert tube with one of their SAG-AT7-MPI's. Right now I have a balanced JJ AT7 thats only a few months old (thanks to Bob@Eurotubes). I understand that GT may have a more rigorous testing/matching system than Bob, but would I notice any difference in sound?

 

Am I correct in assuming that the PI tube has more to do with the lifespan of the power tubes than the sonic quality?

 

On a related subject, this amp has the bias and balance test points on the back panel. The manual says to set the bias with a DVM at between .04VDC and .08VDC. What would be optimal for these tubes?

 

Do these test points give as acurate a reading as as in-line bias meters?

 

OR

 

Should I take it to a tech and have it done with a scope and a signal?

 

 

Kudos and thanks again for all your help.

 

David

[myles_rose]

Originally posted by sgguitarzz:

Dennis,

Thanks Myles. The Blues Junior looks like a pretty good pick at that price. Other considerations would be a Peavey Clasic 30, the new Carvin Vintage 16 and someone mentioned and H&K Edition. ANy thoughts on the Fender vs. these amps?

 

Dennis

Dennis,

 

I think it all boils down to personal preference. Maybe post that question here for all the folks and see what you get back?

 

I like the inside layout of the Fender and its packaging in general. The Classic 30 is .... well .... a classic in a number of ways, and I have owned a lot of Carvin gear over the years that I have been very happy with. Like I said, tough choice.

 

Generally, I think any amp that competes in this price range has to have a degree of features and reliability, and they all fare nicely in that department.

 

I guess all I can say here is .... "good luck"

 

Regards,

[myles_rose]

Originally posted by hechtdavid:

Hi Myles,

 

I just ordered a matched quad of the GT 6L6GE's for my 1999 "Evil" Twin and was wondering if I should replace the phase invert tube with one of their SAG-AT7-MPI's. Right now I have a balanced JJ AT7 thats only a few months old (thanks to Bob@Eurotubes). I understand that GT may have a more rigorous testing/matching system than Bob, but would I notice any difference in sound?

 

Am I correct in assuming that the PI tube has more to do with the lifespan of the power tubes than the sonic quality?

 

On a related subject, this amp has the bias and balance test points on the back panel. The manual says to set the bias with a DVM at between .04VDC and .08VDC. What would be optimal for these tubes?

 

Do these test points give as acurate a reading as as in-line bias meters?

 

OR

 

Should I take it to a tech and have it done with a scope and a signal?

 

 

Kudos and thanks again for all your help.

 

David

David,

 

Bob at Eurotubes does a great matching job, and your phase inverter is a LOT better than anything you'' ever get off the shelf at random. The JJ tubes are pretty consistant in rise time, so I'd just keep that in there for now. If the rise time was off by a bit, if you had a very critical ear, you might notice a difference. I can tell you that at below 100 Hz, I can sure see a difference on a scope when I look at the output waveform when I use one of the SAG tubes.

 

On the GE's .... get ready to be surprised !

 

The PI has a LOT to do with sonic quality. Sure, the output section tubes will last longer too, as they are being driven more evenly, but the sonic quality is the BIG factor. In certain amps they make a major noticible improvement.

 

In your amp I set the GE's at about .05VDC from their testpoints. This makes the amp run a touch on the cool side, but the Twins don't get as grainy when cool as a Mesa amp as an example.

 

The test points on the Fender amps are every bit as accurate as any bias measuring device with a meter. I wish they would have done that system 50 years ago On Fender amps I like the current draw method more than with a scope. It is something that is repeatable, and a scope view is not ... it is open to interpretation. On Marshall amps I like to use a scope as there is a certain amount of crossover notch that is needed to give them their Marshall sound.

 

So ... save your money on the tech and buy a cheap $30 meter, and you are in business

 

Regards,

[oyo]

Major snippage below to keep post length down.

 

[/qb]

John,

 

The phase inverters, as there are two of them in an SVT, are important to be matched.

The line outs are used to slave additional power amps if the need ever arose (which is pretty humorous as the SVT family, old or new, are pretty extreme amps just standing alone. I mean, they were big enough to do the original Woodstock without the help of sound reinforcement

 

A balanced phase inverter will not give you a change in level or tone. What it will do is give you sustain across the entire fret board, especially on bass and its lower frequencies that really tax amps.

So .... in comes GT SAG folks. Now you plug in a tube that is a #100. Down the road you want more compression and less front end distortion, so you order a #80 or so. Or ... you want LOTS of gain, so you go for a #125 maybe.

V1 and V2 are your basic tone shaping tubes, others are used for the tone controls and EQ. Your most important tubes are V1 and your two phase inverters.

 

Regards,[/QB]

 

Thanks again Myles. I wanted to know specificaly about the newer SV P, the preamp only unit from SLM. Does the 12AU7 tube drive the line outs? Even more specificly, does each side of the 12AU7 amplify half the waveform (push-pull style as in a normal SV T ), thus needing a balanced tube, or is there a difference between the stand- alone preamp (SVP) and say the integrated pre in the SVT 2 Pro or SVT 4 Pro heads?

 

Hope I'm making sense...

[myles_rose]

Originally posted by oyo:

Major snippage below to keep post length down.

 

John,

 

The phase inverters, as there are two of them in an SVT, are important to be matched.

The line outs are used to slave additional power amps if the need ever arose (which is pretty humorous as the SVT family, old or new, are pretty extreme amps just standing alone. I mean, they were big enough to do the original Woodstock without the help of sound reinforcement

 

A balanced phase inverter will not give you a change in level or tone. What it will do is give you sustain across the entire fret board, especially on bass and its lower frequencies that really tax amps.

So .... in comes GT SAG folks. Now you plug in a tube that is a #100. Down the road you want more compression and less front end distortion, so you order a #80 or so. Or ... you want LOTS of gain, so you go for a #125 maybe.

V1 and V2 are your basic tone shaping tubes, others are used for the tone controls and EQ. Your most important tubes are V1 and your two phase inverters.

 

Regards,[/QB]

 

Thanks again Myles. I wanted to know specificaly about the newer SV P, the preamp only unit from SLM. Does the 12AU7 tube drive the line outs? Even more specificly, does each side of the 12AU7 amplify half the waveform (push-pull style as in a normal SV T ), thus needing a balanced tube, or is there a difference between the stand- alone preamp (SVP) and say the integrated pre in the SVT 2 Pro or SVT 4 Pro heads?

 

Hope I'm making sense... [/QB]

 

John,

 

The 12AU7 for the outputs does not need to be balanced all that much as there is more inconsistancy in the power amps that may be driven from the line out or a board from the preamp only unit as opposed to the preamp/amp configuration of the old SVT and SVT II products.

 

Regards,

[hechtdavid]

Originally posted by myles111:

Originally posted by hechtdavid:

Hi Myles,

 

I just ordered a matched quad of the GT 6L6GE's for my 1999 "Evil" Twin and was wondering if I should replace the phase invert tube with one of their SAG-AT7-MPI's. Right now I have a balanced JJ AT7 thats only a few months old (thanks to Bob@Eurotubes). I understand that GT may have a more rigorous testing/matching system than Bob, but would I notice any difference in sound?

 

Am I correct in assuming that the PI tube has more to do with the lifespan of the power tubes than the sonic quality?

 

On a related subject, this amp has the bias and balance test points on the back panel. The manual says to set the bias with a DVM at between .04VDC and .08VDC. What would be optimal for these tubes?

 

Do these test points give as acurate a reading as as in-line bias meters?

 

OR

 

Should I take it to a tech and have it done with a scope and a signal?

 

 

Kudos and thanks again for all your help.

 

David

David,

 

Bob at Eurotubes does a great matching job, and your phase inverter is a LOT better than anything you'' ever get off the shelf at random. The JJ tubes are pretty consistant in rise time, so I'd just keep that in there for now. If the rise time was off by a bit, if you had a very critical ear, you might notice a difference. I can tell you that at below 100 Hz, I can sure see a difference on a scope when I look at the output waveform when I use one of the SAG tubes.

 

On the GE's .... get ready to be surprised !

 

The PI has a LOT to do with sonic quality. Sure, the output section tubes will last longer too, as they are being driven more evenly, but the sonic quality is the BIG factor. In certain amps they make a major noticible improvement.

 

In your amp I set the GE's at about .05VDC from their testpoints. This makes the amp run a touch on the cool side, but the Twins don't get as grainy when cool as a Mesa amp as an example.

 

The test points on the Fender amps are every bit as accurate as any bias measuring device with a meter. I wish they would have done that system 50 years ago On Fender amps I like the current draw method more than with a scope. It is something that is repeatable, and a scope view is not ... it is open to interpretation. On Marshall amps I like to use a scope as there is a certain amount of crossover notch that is needed to give them their Marshall sound.

 

So ... save your money on the tech and buy a cheap $30 meter, and you are in business

 

Regards,

Great Myles! Once again, you've got me excited to plug and play. I'm very anxious for those GE's to arrive.

 

One more question: When you say to set the GE's at about .05VDC from their testpoints, does that mean up or down? Since Fender recommends from .04 to .08 VDC, and seeing that .06 is in the middle, should I set it at .11 or .01 VDC?

 

OK, I lied... one MORE question: I've been told that running them cold will yield a longer tube life, but what sonic differences would you expect to hear between running at the upper and lower ends of the bias scale?

 

Thanks again,

 

David

[goodsgtr]

I have a pretty bad buzz(not that kind) in my Musicman 112RD. Is it the tubes if so 6L6GC's are in it now and have been since I bought it 10 years ago. Is this the problem? If so should they be replaced with the same or do you have suggestions? I mostly play a Strat, bluesy, rock.

If this isn't the problem what might it be?

 

Thanks,

Rob

[myles_rose]

Originally posted by goodsgtr:

I have a pretty bad buzz(not that kind) in my Musicman 112RD. Is it the tubes if so 6L6GC's are in it now and have been since I bought it 10 years ago. Is this the problem? If so should they be replaced with the same or do you have suggestions? I mostly play a Strat, bluesy, rock.

If this isn't the problem what might it be?

 

Thanks,

Rob

I'd have to see the amp, but wuth tubes over 10 years old, that would be the first change I would make as it is long overdue, especially in this amp that runs over 600 volts on the plates of the tubes.

 

Regards,

 

Rob,

[Dylan]

Hey Miles....I just ordered a new set of pickups for my 90's Japanese Custom Tele. I haven't ever installed my own pickups before and was wondering if anyone could point me in the right direction. I have no problem paying a pro if need be, but if it's something easy I'd rather do it myself. The pickups are a Fender Custom Shop NOS and a Texas Special.

[myles_rose]

Originally posted by Dillweed:

Hey Miles....I just ordered a new set of pickups for my 90's Japanese Custom Tele. I haven't ever installed my own pickups before and was wondering if anyone could point me in the right direction. I have no problem paying a pro if need be, but if it's something easy I'd rather do it myself. The pickups are a Fender Custom Shop NOS and a Texas Special.

Dillweed,

 

Wiring pickups is not all that tough if you are fair with a soldering iron. The pickups should have come with a wiring diagram. If they did not, I would go to the Fender website and look for Mr. Gearhead. They should have a wiring diagram for a Tele.

 

Regards,

[jazzcaster]

Hello Myles,

 

A quick amateur question here, if you don't mind. I have an 8" speaker (from a Randall practice amp)that has absolutely no markings of any kind on it (nada, zilch, zero!). No spec sheets or anything at the website to help, either. If I want to determine the impedance, and do not have the means (or know-how) to conduct an impedance bench test (ie: under load), can I simply measure the DC resistance? I believe the DC ohm reading will always be less than the "nominal" rating of the speaker, but it will be close. Is this correct??? Thanks in advance!

[trucidation]

hello,

i have the MesaBoogie Bassis M-2000

i bought it used and was thinking of replacing the tubes. would it make a difference if the phaze inverter was balanced in this amp? and what would be the best set of Groove Tubes to put in to get the fattest deepest bass tones?

thank you very much.

trucidation

[myles_rose]

Originally posted by jazzcaster:

Hello Myles,

 

A quick amateur question here, if you don't mind. I have an 8" speaker (from a Randall practice amp)that has absolutely no markings of any kind on it (nada, zilch, zero!). No spec sheets or anything at the website to help, either. If I want to determine the impedance, and do not have the means (or know-how) to conduct an impedance bench test (ie: under load), can I simply measure the DC resistance? I believe the DC ohm reading will always be less than the "nominal" rating of the speaker, but it will be close. Is this correct??? Thanks in advance!

jazzcaster ....

 

Speakers that are 8 ohms as as example, can go from about 8 to much higher at different frequencies, but its "nominal" value is about 8 ohms.

 

Therefore, you are right .... take a conventional ohm meter, and measure across the speaker terminals, and if it is close to 8 ohms, its an 8 ohm speker .... 4 ohm speakers read from 3.7 to maybe 5 as an example.

 

So ... you are in business.

 

Regards,

[myles_rose]

Originally posted by trucidation:

hello,

i have the MesaBoogie Bassis M-2000

i bought it used and was thinking of replacing the tubes. would it make a difference if the phaze inverter was balanced in this amp? and what would be the best set of Groove Tubes to put in to get the fattest deepest bass tones?

thank you very much.

trucidation

trucidation ....

 

Save your money and put away the screwdriver !

 

The 12AX7 front end of this amp is set up for compression characteristics and not for gain. This amp lets you choose between a tube front end or an FET front end, both with a different character .... OR .... you can blend the too, which is cool.

 

On the back end, there are no tubes to replace. They use a big SS backend with a terrific power supply with a lot of reserve capacity. Their power transformer is particularly impressive.

 

In any case, there is a lot of processing done in the front end of these amps, so changing the tubes from the Mesa stock ones is something of an un-necessary expense. These preamp tubes will also last for many years.

 

Now ... if you want to try something really impressive .... plug that amp into a 4x12 cabinet, crank it up on the FET front end, and plug in a Rickenbacker 12 string and play some rhythm guitar! Its a great bass amp for sure, but its also a pretty amazing rhythm guitar amp too and its EQ works pretty nice for some tastes on guitar too!

 

So ... save your money ... save your time, and just play. You have a great rig there just the way it is.

 

Regards,

[jivey311]

I'm going to be retubing my JCM900 and would yellow jacket's or Ruby Tube's Tone Bone's both come with EL84's. How is the difference in tone between 6L6's and EL84's in the yellow jacket's??? More or less gain?

[myles_rose]

Originally posted by jivey311:

I'm going to be retubing my JCM900 and would yellow jacket's or Ruby Tube's Tone Bone's both come with EL84's. How is the difference in tone between 6L6's and EL84's in the yellow jacket's??? More or less gain?

jivey311,

 

I prefer the Yellow Jackets and these are what most of my clients use, and we have never had a single failure of the Yellow Jacket itself, the tube supplied (a really great JJ), or any sort of amp problem when using the Yellow Jackets.

 

6L6's will not fit in a Yellow jacket.

 

Regards,

[Mikibis]

Hi, Myles.. finally can i write to you on this forum...i found a tube...on which was labeled Philips Miniwatt ecc83....i found it in an old valve television....

could i try it in my amps.? is a regular 12ax7...

and why is called miniwatt?...thanks..any suggestion..should i try it in V1...what about this tube...is better to try in my rectoverb or in my jubilee

thanks

Michele

[jivey311]

I wanted to know, what the tone differences are between a EL84 and a 6L6? Like is the EL84 a more built for high gain rather than the 6L6.

[myles_rose]

Originally posted by Mikibis:

Hi, Myles.. finally can i write to you on this forum...i found a tube...on which was labeled Philips Miniwatt ecc83....i found it in an old valve television....

could i try it in my amps.? is a regular 12ax7...

and why is called miniwatt?...thanks..any suggestion..should i try it in V1...what about this tube...is better to try in my rectoverb or in my jubilee

thanks

Michele

Mikibis...

 

That tube is a conventional ECC83, which is part of the 12AX7 family. The "mini-watt" came from their use in some low powered class A amps of about 1/4 - 1/2 watt back in the 50's.

 

It is probably a very good tube to try in any preamp section of most amps, or any amp that uses a 12AX7/7025/ECC83/12AT7/12AU7/12AY7.

 

Regards,

[myles_rose]

Originally posted by jivey311:

I wanted to know, what the tone differences are between a EL84 and a 6L6? Like is the EL84 a more built for high gain rather than the 6L6.

jivey311 ...

 

The EL84 is something of a mini EL-34 in a nine pin bottle. It is much lower in output (about 12 watts max) than a 6L6. It has a nice distortion character that is easy to distort and lower levels, and its distortion builds smoothly throughout its range.

 

They are very different tubes, each with their own great applications.

 

Regards,

[plexiglass]

Hey Myles...

 

I just purchased a new Peavey 5150 II... and I'm picking it up from my local dealer tomorrow. I saw your comments about preamp tubes on the Harmony Central forum. How can I tell if I need to replace a preamp tube that is only running at 50-60%??? Does the amp just sound weak or do the preamp tubes glow with less intensity than ones running at full capacity?? I'm not sure how many preamp tubes the 5150 II has... but it's almost certain now, after reading your posts, that some of them may not be up to PAR. I love high gain... so I guess I should stick to the standard Chinese preamp tubes. Thoughts???

 

Plexiglass

[myles_rose]

Originally posted by plexiglass:

Hey Myles...

 

I just purchased a new Peavey 5150 II... and I'm picking it up from my local dealer tomorrow. I saw your comments about preamp tubes on the Harmony Central forum. How can I tell if I need to replace a preamp tube that is only running at 50-60%??? Does the amp just sound weak or do the preamp tubes glow with less intensity than ones running at full capacity?? I'm not sure how many preamp tubes the 5150 II has... but it's almost certain now, after reading your posts, that some of them may not be up to PAR. I love high gain... so I guess I should stick to the standard Chinese preamp tubes. Thoughts???

 

Plexiglass

The only way to know for sure is to test your present tubes. If you look on my website in the "friends" section, you will see a fellow there named Tom Dunn. He has what Peavey considers the best sounding 5150 II's around. You can probably find him on Harmony Central once in a while and ask him what he went through with his amps.

 

His amps use hand selected preamps tubes and 6L6GE's in the output section with a matched phase inverter.

 

There is a LOT you can do with these amps.

 

Regards,

[Seegs]

Hi Myles,

 

Long time! I've been busy trying to earn a living at this music stuff, unsuccessful thus far, but things are looking up!

 

Question: I remember you stating that the Fender BF and SF deluxes were the only amp unaffected by the CBS buyout. Meaning SF=BF specs. Right???

 

Does that mean totally unaffected, no circuit changes, no lesser quality components, or cabinet material or what exactly was the extent of the changes.

 

Was that the only amp unaffected? ie. champs, princetons??

 

Where can I find more info on this?

 

Thanks in advance.

 

Chow,

Seegs

[Dave da Dude]

Myles, I am just about to receive (it's shipping today) my first tube amp (Randall Pro 1000, 1993).

 

I seem to remember somewhere in the deep, dark recesses of my memory (boy it's scary in there) something about the handling of tubes that said the oil from your fingers (that create fingerprints), if left on a power tube, will create a hot spot and cause early failure.

 

Is there any truth to this? Or was I just smoking wacky tobacee?

 

Dave

[myles_rose]

Originally posted by Seegs:

Hi Myles,

 

Long time! I've been busy trying to earn a living at this music stuff, unsuccessful thus far, but things are looking up!

 

Question: I remember you stating that the Fender BF and SF deluxes were the only amp unaffected by the CBS buyout. Meaning SF=BF specs. Right???

 

Does that mean totally unaffected, no circuit changes, no lesser quality components, or cabinet material or what exactly was the extent of the changes.

 

Was that the only amp unaffected? ie. champs, princetons??

 

Where can I find more info on this?

 

Thanks in advance.

 

Chow,

Seegs

Seegs,

 

The amps from the Deluxe Reverb on down were pretty much left un-touched, as they did not sell for enough to warrant changes from CBS.

 

For really exact details, I'd look at the Fender Amp Field Guide as they may have minute types of info.

 

Regards,

 

Myles

[myles_rose]

Originally posted by Dave th Dude:

Myles, I am just about to receive (it's shipping today) my first tube amp (Randall Pro 1000, 1993).

 

I seem to remember somewhere in the deep, dark recesses of my memory (boy it's scary in there) something about the handling of tubes that said the oil from your fingers (that create fingerprints), if left on a power tube, will create a hot spot and cause early failure.

 

Is there any truth to this? Or was I just smoking wacky tobacee?

 

Dave

Dave,

 

I guess from a pure physics point of view this may have some point, but tubes are not like halogen bulbs. They are more like conventional light bulbs, and I do not wear gloves when I replace light bulbs or tubes.

 

The main point of handling tubes is .... watch out for leaving some of your skin on output tubes when they are super hot ... won't hurt the tube much, but causes people a bit of pain

 

Regards,

[rsf1977]

I have a Mesa-Boogie Dual Rec (2 Channel)

 

I wanted to know how I should go dialing in my ideal tone. Do you set everything at middle of the road and then tweak? Also should I adjust certain frequencies before others?

 

These are the controls I have:

1. Master Volume

2. Channel Volume

3. Presence

4. Bass

5. Mid

6. Treble

7. Gain

 

I like a really thick saturated distortion I play hardcore-metal. If that changes anything?

 

Also is there any tips you can give about the Dual Rec that might really make it sing? Like the mid range is where it's at on this amp so focus around that? or anything that might help.

[myles_rose]

Originally posted by rsf1977:

I have a Mesa-Boogie Dual Rec (2 Channel)

 

I wanted to know how I should go dialing in my ideal tone. Do you set everything at middle of the road and then tweak? Also should I adjust certain frequencies before others?

 

These are the controls I have:

1. Master Volume

2. Channel Volume

3. Presence

4. Bass

5. Mid

6. Treble

7. Gain

 

I like a really thick saturated distortion I play hardcore-metal. If that changes anything?

 

Also is there any tips you can give about the Dual Rec that might really make it sing? Like the mid range is where it's at on this amp so focus around that? or anything that might help.

rsf1977 ...

 

Front panel controls are all set to preference and there is really no specific method. I start with everything flat, because with passive tone controls, in some circuits, if one of them is off, then there is no sound at all.

 

For a thick sound with a lot of articulation still, I use the E34L-S tubes in your amp if you have the bias set for EL-34's, but for max sound, I like the 6L6GE's or the 6L6S tubes for the output tubes.

 

In Mesa amps I use a GT range of 6's or even 7's. 6's are the same as Mesa's hottest tubes, but even these are a bit cool running.

 

On preamp tubes for my clients, I use either 12AX7R3's for V1 and V2 or ECC83's for the folks that want even more mids and sparkle. In either case, I hand pick these to make sure their rating is at least 100 on the scale I use.

 

I always used a Matched Phase Inverter, and I have spoken about this in detail, and it is also explained on my website.

 

Regards,

[rsf1977]

Hey Myles just curious why you use 12AX7R3's for V1 and V2. I currently have 12AX7EH for entire preamp do you think this is a wise decision?

 

also what is the 100 rating, how do I request that Groove Tube only has low/med/high in the SAG sections

 

"On preamp tubes for my clients, I use either 12AX7R3's for V1 and V2 or ECC83's for the folks that want even more mids and sparkle. In either case, I hand pick these to make sure their rating is at least 100 on the scale I use."

[myles_rose]

Originally posted by rsf1977:

Hey Myles just curious why you use 12AX7R3's for V1 and V2. I currently have 12AX7EH for entire preamp do you think this is a wise decision?

 

also what is the 100 rating, how do I request that Groove Tube only has low/med/high in the SAG sections

 

"On preamp tubes for my clients, I use either 12AX7R3's for V1 and V2 or ECC83's for the folks that want even more mids and sparkle. In either case, I hand pick these to make sure their rating is at least 100 on the scale I use."

rsf1977....

 

Actually, the GT-12AX7R3 is the 12AX&EH tube made by the Relector Factory in Russia ... on the west side of the Reflector factory where the EH tooling is set up. On the East side of the factory is where the Sovtek tooling is set up.

 

So... if you have EH's in there now, you are in business.

 

Regards,