Feel free to ask Myles

[roy d]

thanks Myles.

 

I'm out of town for a few weeks so it won't be until mid or late July but I'll give you a call to see what works for you.

[myles_rose]

Originally posted by roy d:

thanks Myles.

 

I'm out of town for a few weeks so it won't be until mid or late July but I'll give you a call to see what works for you.

Roy -

 

That will be fine.

[Caevan O’Shite]

Say, Myles, can you recommend any way that I could use my old GTE SE (the early one, with the resonant-pole-filter EQ, and without any attenuation option) to have a reactive-load style attenuator, a la Power Brake, Hot Plate, Air Brake, Muzzle, and the newer GT SE's and Marshall SE's? (I understand that not all of these mentioned products use the type of reactive loading that the GT- and Marshall- SE's employ, but I want some kind of "volume, post-power-amp/pre-speaker" attenuation.) I would be fine with building an outboard "rig" to use with the SE's reactive load and all, or, provided there's enough room (which I doubt) and no undue complications, adding circuitry and components in the chassis, if you can tell me what I should- and shouldn't- do. (I'm a pretty competent solderer and wiring router, and understand basic electrical safety and quality precautions.)

 

Thanks in advance for your time and effort here! -Kevin, a.k.a. "Caevan O'Shite"

[nonfcomm]

Myles,

 

What is the basic sonic difference between a JAN Phillips 12AX7 and a 7025?

 

Dan

[myles_rose]

Originally posted by CaevanO'Shite:

Say, Myles, can you recommend any way that I could use my old GTE SE (the early one, with the resonant-pole-filter EQ, and without any attenuation option) to have a reactive-load style attenuator, a la Power Brake, Hot Plate, Air Brake, Muzzle, and the newer GT SE's and Marshall SE's? (I understand that not all of these mentioned products use the type of reactive loading that the GT- and Marshall- SE's employ, but I want some kind of "volume, post-power-amp/pre-speaker" attenuation.) I would be fine with building an outboard "rig" to use with the SE's reactive load and all, or, provided there's enough room (which I doubt) and no undue complications, adding circuitry and components in the chassis, if you can tell me what I should- and shouldn't- do. (I'm a pretty competent solderer and wiring router, and understand basic electrical safety and quality precautions.)

 

Thanks in advance for your time and effort here! -Kevin, a.k.a. "Caevan O'Shite"

Kevin,

 

The old GT SE was designed to go directly to a board or a basic amp direct. There is really not a way to attenuate the signal that goes to the cabinet as on the SEII.

 

Sorry.

[myles_rose]

Originally posted by nonfcomm:

Myles,

 

What is the basic sonic difference between a JAN Phillips 12AX7 and a 7025?

 

Dan

Dan -

 

They sound much different, and there are many 7025s.

 

You need my tube primer document, metioned elsewhere in this forum.

[michael c]

Myles, any idea what a GT Speaker Emulator is worth these days? It is the early 90's model.

 

Thank you.

[Djinn1973]

Can I A-B / A-B--Y two heads in to a single cab?

Thanks

[Caevan O’Shite]

Originally posted by michael c:

"Myles, any idea what a GT Speaker Emulator is worth these days? It is the early 90's model.

Thank you."

Yeah, the going rate's about $20.00, I'll even give ya $25.00 if it's real clean...

 

Seriously, I've got no idea, but I do wish I was in a position to make you a decent offer; I love these things, I own an older model, the one that doesn't have the volume/power-reduction like a Hot Plate or Air Brake, and would like one day to get a later model, as well. -k

[myles_rose]

Originally posted by michael c:

Myles, any idea what a GT Speaker Emulator is worth these days? It is the early 90's model.

 

Thank you.

michael c...........

 

I have no idea at all. I have a bunch of them, and still use them all the time.

 

I'd maybe look on ebay?

[myles_rose]

Originally posted by Djinn1973:

Can I A-B / A-B--Y two heads in to a single cab?

Thanks

Not without a very special speaker selector and a way when in "Y" you can change your amp.

[nonfcomm]

Myles,

What affect does the reverb driver tube have on your tone? Is it mostly transparent? What would happen if you changed the type or the model?

 

Dan

[funky hot grits]

Hi Myles,

 

A while ago, I asked you a question about retubing a blue angel head. You mentioned your preference of 12AX7R3's in v1-v4, a SAG-AX7-MPI in V5.

 

Two questions:

 

Can you describe the vatious applications of v1 to v5 in a blue angel. Am I right in assuming that v1-4 are for general preamp duties and v5 is for driving the reverb? Or is the SAG-AX7-MPI you use in V5 being used for a different application? -looking at the blue angel manual, there is no specific info on this matter.

 

Also, can you recommend a selection of tubes for my preamp with maximum clean headroom and warmth as the main goals? -I have access to EHX, GT, sovtek and mesa tubes. I read on the GT site that 12AT7s can be substituted for 12AX7s for more clean headroom. Do you recommend this,and for which spots?

 

 

Also a simple one: If I'm looking into the back of my angel (6v6s to the left), am I right in assuming that v1 is the furthest left of the preamp tubes?

 

thanks in advance,

 

Martin Sutcliffe

[myles_rose]

Originally posted by nonfcomm:

Myles,

What affect does the reverb driver tube have on your tone? Is it mostly transparent? What would happen if you changed the type or the model?

 

Dan

Dan,

 

It depends on the amp circuit, but on Fender style circuits, it is not much in the tone stage, but you do want a tube that is quiet and has proper output.

 

A noisy tube here will make noise everywhere.

[myles_rose]

Originally posted by funky hot grits:

Hi Myles,

 

A while ago, I asked you a question about retubing a blue angel head. You mentioned your preference of 12AX7R3's in v1-v4, a SAG-AX7-MPI in V5.

 

Two questions:

 

Can you describe the vatious applications of v1 to v5 in a blue angel. Am I right in assuming that v1-4 are for general preamp duties and v5 is for driving the reverb? Or is the SAG-AX7-MPI you use in V5 being used for a different application? -looking at the blue angel manual, there is no specific info on this matter.

 

Also, can you recommend a selection of tubes for my preamp with maximum clean headroom and warmth as the main goals? -I have access to EHX, GT, sovtek and mesa tubes. I read on the GT site that 12AT7s can be substituted for 12AX7s for more clean headroom. Do you recommend this,and for which spots?

 

 

Also a simple one: If I'm looking into the back of my angel (6v6s to the left), am I right in assuming that v1 is the furthest left of the preamp tubes?

 

thanks in advance,

 

Martin Sutcliffe

Martin -

 

If you write me and ask for a print, at techsupport@groovetubes.com I will send you a schematic that will show you what all the tubes do and how they interact.

 

The Mesa manual on the BA does not have tube assignments as some of their other amps.

 

From my point of view, I would use:

 

V1 and V2 - 12AX7C

 

V3 and V4 - most any good quiet 12AX7

 

V5 - AX7-MPI

 

The EL84 set - EL84S in a #6 rating or #7 rating.

 

The 6V6 set - a set of GE NOS tubes from Mike at KCA NOS (www.kcanostubes.com) or Doug Preston (www.dougstubes.com). If you want to go the new 6V6 route, then a set of 6V6R (these are the 6V6EH) but in a #6 rating.

 

A 12AT7 can be used in V5 for more clean headroom, but I typically use a 12AX7 that has less gain, as the TC is lower with a 12AX7 than a 12AT7 and this comes into play in this amp. A 12AT7 tube from some makers can cause a bit more background noise in an already somewhat noisy amp that has not been looked into a bit already.

 

This would ONLY be used in V5.

 

Now, in V1, you can also try an NOS 5751. These are nicer than trying a 12AT7 in V1.

 

V1 is closest to the input jack.

[Mitch Harris]

Myles,

Another Stupid Question....

Last night I turned my Vibroking on, heard a pop and some loud hissing and quickly turned it off. After looking at it, I found that the speaker rca plug had somehow come lose. This means that for about 60-90 seconds the amp was on with no speaker load. After I found what was wrong I plugged the speaker jack in and turned the amp on. I got a buzzing (that was not there before) that got louder as you turned the volume up. At this point I shut the amp down and unplugged it figuring I must have fried something.

 

This morning I tried the amp and the buzzing is gone. Everything seems to work right. There might be a slight increase in background hum, but I'm not sure. I might be imagining it.

 

My question is this...what damage can be done to an amp with no speaker load? I seem to remember reading somewhere about output transformer damage and blowing caps. Is this damage immediate or does it occur over time. Even though the amp appears to work ok, should I take it to a tech right now or wait for the next power tube change.

 

Thanks for all the help you provide to the music community.

 

Mitch

[myles_rose]

Originally posted by Mitch Harris:

Myles,

Another Stupid Question....

Last night I turned my Vibroking on, heard a pop and some loud hissing and quickly turned it off. After looking at it, I found that the speaker rca plug had somehow come lose. This means that for about 60-90 seconds the amp was on with no speaker load. After I found what was wrong I plugged the speaker jack in and turned the amp on. I got a buzzing (that was not there before) that got louder as you turned the volume up. At this point I shut the amp down and unplugged it figuring I must have fried something.

 

This morning I tried the amp and the buzzing is gone. Everything seems to work right. There might be a slight increase in background hum, but I'm not sure. I might be imagining it.

 

My question is this...what damage can be done to an amp with no speaker load? I seem to remember reading somewhere about output transformer damage and blowing caps. Is this damage immediate or does it occur over time. Even though the amp appears to work ok, should I take it to a tech right now or wait for the next power tube change.

 

Thanks for all the help you provide to the music community.

 

Mitch

Mitch -

 

Don't panic. As long as you did not try to play for a bit, there is little chance of a problem. The output transformers in the Fender Custom Shop amps are very good ones, and turning an amp on for a few seconds with no playing happening, will not usually have any sort of adverse impact.

 

If you hear some "maybe noise that was not there before", it is probably just a bit of panic from what you did, where now you are overcritical and are hearing things that were probably there before, but went un-noticed.

 

Just go ahead and play the amp, it is probably just fine and dandy.

 

If you are anywhere close to me, I'd be more than happy to take a quick look at it on a scope to verify everything, no charge, as you are a member of this forum.

[Mitch Harris]

Myles,

Thanks for the quick response. I did play a few cords and then the noise started, but the whole episode only lasted 2 minutes at the most. I played the amp for 3 hours tonight and it seems fine. I compared the background hum side by side with my new VibroVerb Custom and they both have about the same background noise levels all the way up the volume knobs. It's amazing how my ears started hearing things when my perception was that I did something to damage the amp!

 

BTW, I tried one of your SAG-FST packages in my Vibroverb Custom and it really improved the tone and reponsiveness of the amp. I want to order one for my Vibroking, but with the GT12ax7R's as that particular amp seems to do best with the stock sovtek 12ax7wa's. I tried a couple of GT12ax7c's but they don't seem to soud as good in the VibroKing. They work great in the Vibroverb Custom though. I'll Email you directly at GT.

 

Once again, thanks a lot for your help.

Mitch

[myles_rose]

Originally posted by Mitch Harris:

Myles,

Thanks for the quick response. I did play a few cords and then the noise started, but the whole episode only lasted 2 minutes at the most. I played the amp for 3 hours tonight and it seems fine. I compared the background hum side by side with my new VibroVerb Custom and they both have about the same background noise levels all the way up the volume knobs. It's amazing how my ears started hearing things when my perception was that I did something to damage the amp!

 

BTW, I tried one of your SAG-FST packages in my Vibroverb Custom and it really improved the tone and reponsiveness of the amp. I want to order one for my Vibroking, but with the GT12ax7R's as that particular amp seems to do best with the stock sovtek 12ax7wa's. I tried a couple of GT12ax7c's but they don't seem to soud as good in the VibroKing. They work great in the Vibroverb Custom though. I'll Email you directly at GT.

 

Once again, thanks a lot for your help.

Mitch

Mitch -

 

I am glad all is fine.

 

On the 12AX7WA being SAG selected - no problem. These have a different response curve than the C tubes, so it you prefer them over the C, I can understand that as it is a matter of personal taste.

 

You can email me at GT, or just call me (that might be easier, as I can ask you some questions and dial in closer) toll free at 1-800-459-5687.

[James-Italy]

Originally posted by myles111:

Originally posted by Chipotle:

Myles, I read your review of the Ruby Tubes EL34B-STR and thought I might try either a pair of those or a pair of the GTKT66 HP's in this JTM45 type thing. I was thinking a #4 rating for the KT66's, but how does one specify an equivalent power rating for the Ruby tubes? I was planning on buying from Antique Electronic Supply who do some type of matching for $1 per tube.

Chipotle .............

 

In a JTM-45, to my thinking, the KT66HP is the only way to go. It was the original tube.

 

If your amp has about 400 B+ and a GZ34 rectifier, get these in a #6, and bias at 36mA (some may say bias higher, but then the amp gets a bit harsh at some settings). Make sure V1-V3 are ECC83 and not 12AX7 or 7025 tubes (ECC83's were original and do sound different), and make sure V3 is a matched phase inverter, and not just matched for gain, but matched for rise time also, as in these amps, it is one piece of the magic.

Myles,

Found this old post regarding the JTM45. I just bought one new that has the 2x5881 and 3xECC83. I like the sound now, but know what good tubes can do (ala THD Univalve). I was going to order from Watford (which is the best for me here in Italy- no customs or duties to pay). Just wanted to check with you first since you're the expert!

2xKT66 Harma

3xECC83 JJ Tesla

GZ34 Sovtek Rectifier (a GZ34 is in the JTM, but don't know what make)

 

Will I notice an improvement?

Do I have to do anything besides Re-bias?

 

Thanks Myles- You Rock!

[James-Italy]

Originally posted by myles111:

The new JTM-45's use 5881's (as did some of the originals in the old days, and others used KT-66's.)

 

The "ECC83" marked tubes in many Marshall amps these days are not ECC83 tubes, but 12AX7 tubes which I have seen with "ECC83 Marshall" screening. They are of various 12AX7 makes.

 

The JJ short plate ECC83 is a real ECC83, and this is what I would use.

 

Watford Valves in the UK is a GREAT tube supplier. Their JJ ECC83's would be great. Their Harma KT-66 tubes are of the Chinese variant, which do not have the curves of the GEC tubes (or the KT-66HP), but will be nice enough.

 

If you want the KT-66HP, in Europe, then just contact

 

Groove Tubes Europe c/o Guitar XS Ltd. - Doug Chandler or Tina Shapre

Thomas Point 12a Waterside

Upper Brents, Faversham, Kent, ME13 7AU

Kent, Email: Doug@guitarXS.com

Phone: +44 (0)1795 538877

Fax: +44 (0)1795 538877

 

or ............. if you want them in Italy,

any of the GT products (as the KT-66HP is a GT built tube and not sold by others)

 

MCAS / M. Casale Bauer S.P.A.

Via IV Novembre, 6/8

40057 Cadriano di Granarolo

(Bo), P. IVA 00542121207, Email: info@casalebauer.com

Phone: 39 051 7666

Fax: 39 051 7660

 

These folks would also have the ECC83's.

Thanks Myles!

 

I ordered 11 tubes today from Watford, but waited on the JTM45 replacements till I heard from you. Glad I did! I'll track down some (non Chinese) KT66's at the places you listed above.

 

Today from Watford I ordered (for the Univalve):

2x 6L6GC Harma STR

2x ECC82/12AUTWA R.T.

2x ECC83/ECC83S JJ Tesla

2x ECC81/12AT7WC Phillips

1x EL84 Harma STR

1x 6V6GT RCA (supposed to be really good)

1x 6V6GT Mazda (can you tell I like the 6V6's?)

 

Separatley I ordered a YellowJacket so I can use the EL84 in the Univalve.

 

Thank again Myles- you are the man!

[James-Italy]

Myles.....

 

I don't even know where to start. To think that last October when I stumbled over this forum I knew very little about amps, and even less about tubes.

 

You've turned me on to the THD Univalve which is the best guitar tool around. I just don't understand how anyone who can afford one doesn't have one. To be able to use different tubes and completely change the sound of the amp in 15 seconds is incredible. With the Univalve I've discovered sounds I've only dreamed of attaining. Used as a pre-amp into a great head the possibilities are endless. The Univalve must be the most underrated amp in existance.

 

You are really a great guy to help all of us here on the forum. I can't thank you enough.

 

Three Cheers for Myles!!!!

[aeon]

Myles:

 

I have never done the wiring in a guitar before, but I have attempted to design a layout for one.

 

Guitar will be a Tele, with a Joe Barden T-Style in the bridge and a Barden Two-Tone in the neck. The Two-Tone is a 6-wire humbucker with a true dual-coil-tap.

 

It uses a 5-position megaswitch, 250k pots and a capacitor of undetermined value

 

Would you mind taking a look at it and letting me know if it looks workable to you?

 

thanks in advance,

aeon

[steve f]

Myles, I've got a NOS pair of the big bottle GE 6CA7s. Will these stand up to plate voltages in the 450-475 range?

[myles_rose]

Originally posted by James-Italy:

Myles.....

 

I don't even know where to start. To think that last October when I stumbled over this forum I knew very little about amps, and even less about tubes.

 

You've turned me on to the THD Univalve which is the best guitar tool around. I just don't understand how anyone who can afford one doesn't have one. To be able to use different tubes and completely change the sound of the amp in 15 seconds is incredible. With the Univalve I've discovered sounds I've only dreamed of attaining. Used as a pre-amp into a great head the possibilities are endless. The Univalve must be the most underrated amp in existance.

 

You are really a great guy to help all of us here on the forum. I can't thank you enough.

 

Three Cheers for Myles!!!!

James ...........

 

Thanks lots for the kind words.

 

In regard to the THD Univalve, I don't really think if it as an amp - I think of it more as a swiss army knife, as it does so much.

 

I know you have discovered a lot of cool aspects of the UV for normal "amp use" ... but try to experiment as much as you can using it as a preamp. It will open up all sorts of amazing possibilities. It can turn a very clean high headroom amp like a Fender Twin Reverb into a high gain ultra rock amp.

 

Happy Playing!

[myles_rose]

Originally posted by aeon:

Myles:

 

I have never done the wiring in a guitar before, but I have attempted to design a layout for one.

 

Guitar will be a Tele, with a Joe Barden T-Style in the bridge and a Barden Two-Tone in the neck. The Two-Tone is a 6-wire humbucker with a true dual-coil-tap.

 

It uses a 5-position megaswitch, 250k pots and a capacitor of undetermined value

 

Would you mind taking a look at it and letting me know if it looks workable to you?

 

thanks in advance,

aeon

aeon..........

 

This looks really nice. I also will compliment you on your drafting.

 

In any case, this looks versitile and should work very nicely. I'd love to hear one of these when they are done.

 

Good luck ........

[myles_rose]

Originally posted by steve f:

Myles, I've got a NOS pair of the big bottle GE 6CA7s. Will these stand up to plate voltages in the 450-475 range?

Steve ............

 

Piece of cake ....... the big bottle GE 6CA7 will go to 800 ..... yes ......... 800 plate volts.

 

They are one of the few tubes that will stay alive in the EL-34 based Music Man amps with 700-750 plate volts.

 

They also sound amazing, which does not hurt as an added benefit. In a Marshall, they are just incredible.

[James-Italy]

Myles,

In the Univalve- when I run an EL84 with the YellowJacket, do I have to run it "ONLY" in LoV like the 6V6's?

 

Will the Mazda 6V6 I just got blow if I run them in HiV? (don't want to risk it without checking with you, but if they will hold up to 465+ plate volts you said... maybe HiV will render a different sound)

 

Thanks!

[Mike Gug]

Myles,

 

I'm new to the forum (love it so far), and I haven't read much of your stuff, but from what I've seen, you look like a good candidate to ask this question.

 

I'm sold on the idea of tubes sounding REALLY good, but for someone who hasn't found a "sound", plays in a church band which plays a good range of songs/sounds and likes to screw around with different band covers (mostly rock), would you suggest a modeling amp (1 x 12 please) or a tube amp with good pedals? Under $900?

 

Thanks!

[paranoid]

I proudly own a '72 PTP Marshall superbass which I use as a guitar amp. I fell the need to inprove the 3 preamp tubes because I think that head "needs" high-quality tubes.

I want to keep the typical Marshall sound. What do you suggest me mainly for v1 and v2?

I want to spend not more than 60-70 $.

Thanks for your help.