Feel free to ask Myles

[myles_rose]

Say, Myles...

 

If an output-transformer is suspected of being bad, you just disconnect it, throw a DMM across it for continuity and possibly for resistance to get an idea of how close to spec'ed impedance it is, right?

 

What would you think if an amp repair-tech said he couldn't tell you wether an O/T was good or bad without a replacement on hand to compare it to or swap-out to see if the amp then worked with the replacement?

 

You are basically right here.

 

There are sort of three different output transformer families ... 6V6 / EL84 (yup ... they are the same), 6L6 and EL34.

 

Many parts houses on the net also print the impedances expected when measured so a replacement would never be necessary and if one was it would take longer to check going back and forth. It would be easier to just read the spec and measure things. But then again ... if the tech is not too swift he may have no idea on what wires go to what winding and if that is the case he sould find a new line of work.

 

Output transformers are even easier in some cases as they may not have all the wires that a power transformer may have to deal with various wall voltages. But there are output transformers that will have a 4-8-16 ohm output winding which may confuse somebody who does not have a clue in the first place BUT they should understand enough to know what wires go to the plates of the tubes and that right there will at least get you onto the first plane of understanding.

 

In Aspen Pittman's Tube Amp Book it also explains how to test transformers if you have no spec, no data and know nothing other than how to use a meter.

 

Sounds like you need a new tech

 

 

[Wolfgangsta]

Myles,

 

I'm looking at a Kitty Hawk M3 amp on ebay. The listing says it has new Mesa Boogie 6L6GC tubes and a Celestion G12M70 speaker. Before I pull the trigger and bid, I'm curious if you might have some words of knowledge about said amp. Thanks in advance for your trusted information!

[myles_rose]

Myles,

 

I'm looking at a Kitty Hawk M3 amp on ebay. The listing says it has new Mesa Boogie 6L6GC tubes and a Celestion G12M70 speaker. Before I pull the trigger and bid, I'm curious if you might have some words of knowledge about said amp. Thanks in advance for your trusted information!

 

I do not have a clue what that amp is.

 

 

[Wolfgangsta]

Thanks anyway Myles!

[Caevan O’Shite]

And thanks from me, too, Myles!

[steve f]

Myles, I've got a few U.S. made 6V6GT tubes, what wattage are these considered to be for biasing purposes?

[myles_rose]

Myles, I've got a few U.S. made 6V6GT tubes, what wattage are these considered to be for biasing purposes?

 

14 watts

[JLD]

I just joined the forum and posted my first question regarding the use of a variac ahead of a tube amp. I wish I had read your posting first. I posted that I had recently read an article by a botique amp builder that indicated it was not harmful to a tube amp to utilize a variac for overdriving the amp at lower volumes. He indicatd that 80 to 85 volts was typically the lowest input voltage that should be used. He advised that tube life would be affected by that it was not significant. Do you have any advice regarding this issue?

[myles_rose]

I just joined the forum and posted my first question regarding the use of a variac ahead of a tube amp. I wish I had read your posting first. I posted that I had recently read an article by a botique amp builder that indicated it was not harmful to a tube amp to utilize a variac for overdriving the amp at lower volumes. He indicatd that 80 to 85 volts was typically the lowest input voltage that should be used. He advised that tube life would be affected by that it was not significant. Do you have any advice regarding this issue?

 

This is nonsense.

 

DO NOT use a variac to alter voltages for amps.

 

USE a variac to supply proper design voltages to an amp on a bench when it is being worked on if your shop does not have proper AC voltage.

 

 

[WaterMan]

Myles,

 

What do you think of Mesa's Lonestar Special? Mesa's not in your World's Greatest Amps section -- any particular reason?

[myles_rose]

Myles,

 

What do you think of Mesa's Lonestar Special? Mesa's not in your World's Greatest Amps section -- any particular reason?

 

The Lonestar Special is a decent amp but I am not too big on their EL84 amps in general. It tries to be too many things in one box and when that is attempted you end up with many compromises and nothign that really excells.

 

The 6L6 Lonestar is a much nicer amp for my personal tastes but then again, that is my personal taste. If you like the Special then it is a good value for the money if the amp does what you like it to do. I have a lot of Mesa amps myself and they do have their place when it comes to amps like the Mark Series amps or the Recto amps.

 

 

[WaterMan]

Thanks Myles. I'm looking for a low-watt complement to my Victoria Regal, which I run with either 6L6s or 6V6s, because I too prefer the sound of those tubes. The Lonestar seems like it may be too powerful (loud), although it does have a 10 watt option? I was also tempted by the Carr Rambler, but I've heard it too is pretty loud. If you have any other suggestions for a great blues amp to play primarily in a bedroom environment (and recording), I'm all ears.

 

Thanks again.

[myles_rose]

Thanks Myles. I'm looking for a low-watt complement to my Victoria Regal, which I run with either 6L6s or 6V6s, because I too prefer the sound of those tubes. The Lonestar seems like it may be too powerful (loud), although it does have a 10 watt option? I was also tempted by the Carr Rambler, but I've heard it too is pretty loud. If you have any other suggestions for a great blues amp to play primarily in a bedroom environment (and recording), I'm all ears.

 

Thanks again.

 

My personal favorite is the Dr. Z Carmen Ghia.

 

 

[WaterMan]

OK. Last question on this: I had a Dr. Z Maz Jr, also at 18 watts as you know, and it was really powerful. An absolutely great amp, but really needed to be opened up to sing. I do most of my playing in a small room/studio, and it was just too much. I'm concerned that the Ghia will be in the same league. Is that true? If so, any recommendations for something a bit less powerful?

[myles_rose]

OK. Last question on this: I had a Dr. Z Maz Jr, also at 18 watts as you know, and it was really powerful. An absolutely great amp, but really needed to be opened up to sing. I do most of my playing in a small room/studio, and it was just too much. I'm concerned that the Ghia will be in the same league. Is that true? If so, any recommendations for something a bit less powerful?

 

The Carmen Ghia is a much more gainy amp and will have a great crunch tone at as low at 9 o'clock.

 

It also has lower voltages due to a 5Y3 rectifier so it will also be more touch sensitive and push the output tubes quite diffently along with the tone filter which works on the output section rather than the preamp section.

 

Completely different amps. There are two similar traits ... they are both Dr. Z amps and both use an EL84 duet. That is about all they have in common.

 

 

[WaterMan]

OK then. I'll check one out. Let me know if you know of anyone wanting to get rid of a 1x12 combo. I assume a Celestion Blue would sound great in this amp.

 

Thanks Myles.

[myles_rose]

OK then. I'll check one out. Let me know if you know of anyone wanting to get rid of a 1x12 combo. I assume a Celestion Blue would sound great in this amp.

 

Thanks Myles.

 

As far as finding a good one look here for great info -

http://drzamplifiers.proboards41.com/index.cgi?board=ghia

 

and here to find one for sale -

http://drzamplifiers.proboards41.com/index.cgi?board=BST

 

A vox blue is about as great as it gets but these amps sound amazing through anything. I play mine through a Z-Best 2x12 a lot (V30 & H30) and a 4x12 Marshall cab as well as lots of 1x12 cabs.

 

 

 

 

[Bluesape]

Hey Myles,

 

I bought a Lifco Cobra Mark2 amp, and from what I can gather, it uses the AB763A circuit, with 6V6's and 12AT7's. I just swapped those out for 6L6's and 12AX7's that seem to wake it up some, but it's strictly gainy sounding. I found a post on HC where a guy says he's modded these from Class A to AB, and can get 22 watts from it, and tone like a Deluxe Reverb. I'd like to get some clarity out of this unit, cuz right now it's stictly distorted and underpowered. I't's almost definitely from the 60's, with a tube rectifier, and all point to point. Any ideas or schematics?

[myles_rose]

Hey Myles,

 

I bought a Lifco Cobra Mark2 amp, and from what I can gather, it uses the AB763A circuit, with 6V6's and 12AT7's. I just swapped those out for 6L6's and 12AX7's that seem to wake it up some, but it's strictly gainy sounding. I found a post on HC where a guy says he's modded these from Class A to AB, and can get 22 watts from it, and tone like a Deluxe Reverb. I'd like to get some clarity out of this unit, cuz right now it's stictly distorted and underpowered. I't's almost definitely from the 60's, with a tube rectifier, and all point to point. Any ideas or schematics?

 

If it is an AB763 circuit just assure V6 is a 12AT7. The amps actually put out close to 30 watts if they have 425 or so plate volts.

 

Prints or links to prints are on my website.

 

 

[Rampdog]

Myles... I have a speaker that I would like to know who made it. We've put it in a Peavey Classic 30 and love the sound...

Here's all the info I could get from it...

 

The speaker came from a 1972 Alamo Futura Reverb 2567.

 

On the back it says:

 

12L A50

137 - 7242

Application Engineered for Alamo Electronics

 

On the back of the cone is:

 

1252 T (I think it's a "T").

 

Thanks...

Billy

 

[myles_rose]

Myles... I have a speaker that I would like to know who made it. We've put it in a Peavey Classic 30 and love the sound...

Here's all the info I could get from it...

 

The speaker came from a 1972 Alamo Futura Reverb 2567.

 

On the back it says:

 

12L A50

137 - 7242

Application Engineered for Alamo Electronics

 

On the back of the cone is:

 

1252 T (I think it's a "T").

 

Thanks...

Billy

 

I have no idea and I am not near my book but that 137 number would probably be the code of the original maker. Look in some book like The Tube Amp Book or some electronic books for a list of these codes.

[Bluesape]

Hey Myles,

 

I bought a Lifco Cobra Mark2 amp, and from what I can gather, it uses the AB763A circuit, with 6V6's and 12AT7's. I just swapped those out for 6L6's and 12AX7's that seem to wake it up some, but it's strictly gainy sounding. I found a post on HC where a guy says he's modded these from Class A to AB, and can get 22 watts from it, and tone like a Deluxe Reverb. I'd like to get some clarity out of this unit, cuz right now it's stictly distorted and underpowered. I't's almost definitely from the 60's, with a tube rectifier, and all point to point. Any ideas or schematics?

 

If it is an AB763 circuit just assure V6 is a 12AT7. The amps actually put out close to 30 watts if they have 425 or so plate volts.

 

Prints or links to prints are on my website.

 

 

 

Wow! Thx, bud!

[speeknspell]

Myles - I'm newly joined here but not newly aware of your expertise. Thanks a mil. Another Fender question. I tried to do the old search before you post, but couldn't seem to get very far.

 

Anyway - I have gotten it into my mind that the Fender Tone-Master may be a great amp for me. unfortunately, I have never played one myself. My goal is quite simple - fender sparkly clean channel, but takes my fuzz and distortion pedals well. My favorite fender sounds are the bassman and the deluxe reverb, but I'm looking for something i can hook cabs up to. Hence my interest in a head. I tried a mesa boogie lone star thinking this might hit the spot, but it was horribly not musical.

 

So how would you describe the Tone-Master's clean channel? I've heard a lot of people say they got rid of theirs because it seemed to be too powerful no matter what. I'm just trying to make an informed decision if I ever see one in person.

[myles_rose]

Myles - I'm newly joined here but not newly aware of your expertise. Thanks a mil. Another Fender question. I tried to do the old search before you post, but couldn't seem to get very far.

 

Anyway - I have gotten it into my mind that the Fender Tone-Master may be a great amp for me. unfortunately, I have never played one myself. My goal is quite simple - fender sparkly clean channel, but takes my fuzz and distortion pedals well. My favorite fender sounds are the bassman and the deluxe reverb, but I'm looking for something i can hook cabs up to. Hence my interest in a head. I tried a mesa boogie lone star thinking this might hit the spot, but it was horribly not musical.

 

So how would you describe the Tone-Master's clean channel? I've heard a lot of people say they got rid of theirs because it seemed to be too powerful no matter what. I'm just trying to make an informed decision if I ever see one in person.

 

The Tone-Master is a very loud amp but if you know how to use it then it is very wide in use and scope.

 

Read the Tone-Master manual (downloadable off the Fender website) in regard to the Low-Med-High switch for the speaker jacks that will change the power from 30-60-100 watts.

 

The clean is pretty amazing but the amp has more of a Marshall front end than a black face front end so a Twin Reverb driving the same cab might have a different sort of clean headroom that is hard to describe. It is not a sparkle clean as some blackface tones it is more of a huge wave breaking without much foam. User subjective but I don't think too many people say the amp lacks clean headroom

 

In any case, these amps are something of the Bentley Turbo R of the ampworld and I cannot begin to list all the heavy guitar icons that use them without it being common knowledge as the list is pretty extensive.

 

 

[speeknspell]

thanks so much for your reply. it has really helped me understand the amp better - sounds like i defininitely need to try one before ever buying it! really appreciate your know how

[Zephyr]

Hey Myles, I've got a few questions. First, do I have to re-bias an amp for an ECC83 if they normally take 12AX7's?

 

Secondly, I'm looking to re-tube my Fender Deluxe Reverb Reissue. My plans are as follows:

 

V1: Tung-Sol 12AX7

V2: JJ ECC83S

V3: NOS Mullard CV4024

V4: Tung-Sol 12AX7

V6: NOS Mullard CV4024

 

Power Tubes: NOS Brimar/STC 6V6

Rectifier: NOS GE 5AR4

 

Do you have any idea what this set-up would do? What I'm basically hoping to achieve is a sound that has enough clean headroom that breaks up at around 3, and gets particularly aggressive at higher volumes with levels of gain that can get rock n roll grind. I've also heard that those Mullard's can smooth out the top end a bit correct? Additionally, do you know of any way to make the Deluxe Reverb sound more "brown"?

 

Thanks for reading and help is much appreciated.

[myles_rose]

Hey Myles, I've got a few questions. First, do I have to re-bias an amp for an ECC83 if they normally take 12AX7's?

 

Secondly, I'm looking to re-tube my Fender Deluxe Reverb Reissue. My plans are as follows:

 

V1: Tung-Sol 12AX7

V2: JJ ECC83S

V3: NOS Mullard CV4024

V4: Tung-Sol 12AX7

V6: NOS Mullard CV4024

 

Power Tubes: NOS Brimar/STC 6V6

Rectifier: NOS GE 5AR4

 

Do you have any idea what this set-up would do? What I'm basically hoping to achieve is a sound that has enough clean headroom that breaks up at around 3, and gets particularly aggressive at higher volumes with levels of gain that can get rock n roll grind. I've also heard that those Mullard's can smooth out the top end a bit correct? Additionally, do you know of any way to make the Deluxe Reverb sound more "brown"?

 

Thanks for reading and help is much appreciated.

 

Preamp tubes are plug and play ... no bias necessary as they are self biasing.

 

On preamp tubes, that is all user taste and preference. The 12AX7M will tame an amp that is too bright for some tastes. I use the M's in my Fender blackface amps ... deluxe reverb and twin reverb in V1, V2, V5.

 

The deluxe reverb is not an agressive amp but it can be made a bit more agressive by replacing the 12AT7 phase inverter in V6 with a 12AX7 phase inverter.

 

 

 

[Zephyr]

Okay, great, so Groove Tube's produces the 12AX7M right?

 

And also as you said, I don't need to bias pre-amp tubes, so would it become more aggressive if I put a low gain 12AX7 in it, say a 5751?

[myles_rose]

Okay, great, so Groove Tube's produces the 12AX7M right?

 

And also as you said, I don't need to bias pre-amp tubes, so would it become more aggressive if I put a low gain 12AX7 in it, say a 5751?

 

The 12AX7M is a GT exclusive tube. Nobody else has the tube.

 

A 5751 will make the amp less gainy, less agressive and yield more clean headroom.

 

 

[steve f]

Myles,

 

I'd like to hear your take on the JAN-Philips 6L6WGB tubes from the 80s. It's been said that these have a similar plate structure to 7581As, but are rated as a 30 watt tube, similar to a 6L6GC. Would you say they can used as a direct substitute for a 6L6GC? Any opinions as to life expectancy in amps with 450-500 plate volts compared to a 6L6GC?