Feel free to ask Myles

[A String]

Hey Myles! Hope you are doing well!

 

I'm getting an old Traynor YSR-1 Custom Reverb. Two things I wanted to know.

 

How would I convert the two prong into a three? Is it as simple as just soldering on the two wire to the same spot and adding the third to the chassis, or is there more to it then that?

 

Also, any tubes I should be upgrading to or are the originals ok?

[myles_rose]

Hey Myles! Hope you are doing well!

 

I'm getting an old Traynor YSR-1 Custom Reverb. Two things I wanted to know.

 

How would I convert the two prong into a three? Is it as simple as just soldering on the two wire to the same spot and adding the third to the chassis, or is there more to it then that?

 

Also, any tubes I should be upgrading to or are the originals ok?

 

Craig,

 

The old Traynors are pretty darn cool amps.

 

On the plug ... you should really take it to a tech to have it done right. You may want a cap installed in the AC circuit for protection from input spikes and also a good tech would use the proper area for the ground.

 

If the original tubes test good old mfg tubes are generally better than new production. If you have some way of getting them to me I would be happy to test them for you as a favor at N/C but if you know somebody with a mutual conductance tester they could check them out for you very quickly.

 

 

 

[A String]

Thanks Myles. I'll check around and see if I can find any good amp techs here in town.

[Caevan O’Shite]

Myles- what do you think about the following method for bedding-in filter-caps when replacing them, that I found posted elsewhere on-line? Would this be advisable?

 

(I also have to wonder about the following statement about using a variac for bedding-in filter-caps being bad for your tubes; I'd think that, with no signal going through the amp, just bringing up the AC slowly with noting plugged into the input, it wouldn't have any adverse impact on the tubes... ?)

______________________________________________________________________________

(Quoted from another 'site)

 

"Re-form" electrolytic caps

 

You'll hear folks talk about "bringing an amp up slowly on a variac"; this can work but is not particularly good for your tubes. A better way is this:

 

1. Pull out all the tubes.

 

2. If your amp has a tube rectifier, solder in temporarily some high voltage silicon diodes across the tube lugs to be a rectifier that does not depend on the filament voltages. If your amp has silicon diodes, you can skip this. (EDIT: I'd just temporarily pop a pin-based SS-rectifier replacement into the rectifier-tube's socket- CO'S)

 

3. Open up the wire that goes from the rectifier tube (or solid state diodes) to the first power supply filter stage and solder in series with the wire a temporary 100K 2- 5W resistor. This resistor will limit the current that can flow into the caps and the amount of voltage that is applied to them to safe values that will cause the insulating layer to re-form.

 

4. Clip your voltmeter across the resistor

 

5. Button it up. Turn it on (no tubes in it, remember). Watch the voltmeter.

 

6. When the voltmeter reading drops to less than 20-30VDC, your caps are formed.

 

7. Open it back up and pull out those diodes and resistor, putting it back in original shape.

 

The forming could take hours to days.

______________________________________________________________________________

 

Waddya think?

[myles_rose]

Thanks Myles. I'll check around and see if I can find any good amp techs here in town.

 

Craig,

 

Call 65amps next week and ask for Joe Bourdet. He may have some ideas as his family is up north and knows tons of folks up your way.

 

 

[myles_rose]

Myles- what do you think about the following method for bedding-in filter-caps when replacing them, that I found posted elsewhere on-line? Would this be advisable?

 

(I also have to wonder about the following statement about using a variac for bedding-in filter-caps being bad for your tubes; I'd think that, with no signal going through the amp, just bringing up the AC slowly with noting plugged into the input, it wouldn't have any adverse impact on the tubes... ?)

______________________________________________________________________________

(Quoted from another 'site)

 

"Re-form" electrolytic caps

 

You'll hear folks talk about "bringing an amp up slowly on a variac"; this can work but is not particularly good for your tubes. A better way is this:

 

1. Pull out all the tubes.

 

2. If your amp has a tube rectifier, solder in temporarily some high voltage silicon diodes across the tube lugs to be a rectifier that does not depend on the filament voltages. If your amp has silicon diodes, you can skip this. (EDIT: I'd just temporarily pop a pin-based SS-rectifier replacement into the rectifier-tube's socket- CO'S)

 

3. Open up the wire that goes from the rectifier tube (or solid state diodes) to the first power supply filter stage and solder in series with the wire a temporary 100K 2- 5W resistor. This resistor will limit the current that can flow into the caps and the amount of voltage that is applied to them to safe values that will cause the insulating layer to re-form.

 

4. Clip your voltmeter across the resistor

 

5. Button it up. Turn it on (no tubes in it, remember). Watch the voltmeter.

 

6. When the voltmeter reading drops to less than 20-30VDC, your caps are formed.

 

7. Open it back up and pull out those diodes and resistor, putting it back in original shape.

 

The forming could take hours to days.

______________________________________________________________________________

 

Waddya think?

 

 

There are many methods for doing this but what generally works and is very effective is just to plug the amp into a variac when new filter caps are installed when you power up for the first time and take about a minute or two to bring voltage to line level during the sweep from 0 - 120 or whatever. It does not have to be as complicated as the above multi step procedure.

 

 

[Caevan O’Shite]

Cool, thanks!

 

Can I ask another question?

 

In shopping for 150v M.O.V.'s to install across the primary by the power-switch for surge-protection, what other specific specs should I go with? (Looking 'em up on the Mouser Electronics 'site, they have this vast number of specs you have to choose from for searching for M.O.V.'s on their 'site.)

 

For that matter, is 150v an alright value to go with for this, or is that defeating the purpose? I understand that the 130v M.O.V.'s tend to short too easily, too quickly...

 

What would you use? (Do you ever use these?)

[confusedinNC]

Myles,

 

I am having a peculiar noise coming from my amp... HELP!

I purchased my frist tube amp about 5 months ago. It was an Orange AD30. It was brand new, right out of the box. a couple weeks ago i started hearing this loud popping noise when i would turn the amp on and then engage the standby. the popping ceases once my tubes have had a lot of time warming up... however, i dont think that this noise would be a usual result of a tube not having warmed up enough... although i could just be wrong about that, this is my first tube amp afterall...

 

now... this popping doesnt fluctuate in volume if i turn my amp volume up or down, it stays the same volume. However, when i switch from clean to dirty, the popping becomes dirty... A friend of mine believes it is a bad capacitor, but maybe i just need to replace one of the tubes?

 

please help!

[myles_rose]

Cool, thanks!

 

Can I ask another question?

 

In shopping for 150v M.O.V.'s to install across the primary by the power-switch for surge-protection, what other specific specs should I go with? (Looking 'em up on the Mouser Electronics 'site, they have this vast number of specs you have to choose from for searching for M.O.V.'s on their 'site.)

 

For that matter, is 150v an alright value to go with for this, or is that defeating the purpose? I understand that the 130v M.O.V.'s tend to short too easily, too quickly...

 

What would you use? (Do you ever use these?)

 

I have used these and when I do I go with a 600v spec. You can generally get these at Mojo or Antique Electric Supply as two of many sources.

 

 

[myles_rose]

Myles,

 

I am having a peculiar noise coming from my amp... HELP!

I purchased my frist tube amp about 5 months ago. It was an Orange AD30. It was brand new, right out of the box. a couple weeks ago i started hearing this loud popping noise when i would turn the amp on and then engage the standby. the popping ceases once my tubes have had a lot of time warming up... however, i dont think that this noise would be a usual result of a tube not having warmed up enough... although i could just be wrong about that, this is my first tube amp afterall...

 

now... this popping doesnt fluctuate in volume if i turn my amp volume up or down, it stays the same volume. However, when i switch from clean to dirty, the popping becomes dirty... A friend of mine believes it is a bad capacitor, but maybe i just need to replace one of the tubes?

 

please help!

 

This is not a tube issue. Many amps do this and one JTM45 of mine did this too. This can be a few things but the easiest solution to is try another amp of the same type. If it does the same thing it is just inherent to the design. If it does not do the same thing take your amp to another place where you can see if it is related to the ground where you are using the amp. If it turns out to be your ground have that fixed. If it turns out not to be any of these things (as in your amp makes the pop and others do not) then take the amp to a qualified tech as it can be a few different things.

 

 

[Caevan O’Shite]

I have used these and when I do I go with a 600v spec. You can generally get these at Mojo or Antique Electric Supply as two of many sources.

 

Thanks! I'll tell 'em you sent me.

[Fumblyfingers]

Hi Myles.

 

I have a Crate V-18 112 combo with a single 12" speaker.

 

As far as tubes, what can I do to this little fella to get a bit more "sparkle" out of it. I find it a bit muddy especially with a humbucker equipped guitar and at practice levels. I mean even with my old '64 Strat I have to employ an RC Boost with the bass backed off to get that sparkly tone.

 

I notice that the bass control is over the top at 3-4 even while with the treble at 10 I am wishing for more.

 

Another thing I notice is increased hum as I raise the reverb level.

 

Any recommendations?

 

Here is a rough schematic...LOL I am sure it is way basic but figured to throw it in.

 

http://i32.photobucket.com/albums/d42/Gypsyfingers/Picture3-4.png

 

[myles_rose]

Hi Myles.

 

I have a Crate V-18 112 combo with a single 12" speaker.

 

As far as tubes, what can I do to this little fella to get a bit more "sparkle" out of it. I find it a bit muddy especially with a humbucker equipped guitar and at practice levels. I mean even with my old '64 Strat I have to employ an RC Boost with the bass backed off to get that sparkly tone.

 

I notice that the bass control is over the top at 3-4 even while with the treble at 10 I am wishing for more.

 

Another thing I notice is increased hum as I raise the reverb level.

 

Any recommendations?

 

Here is a rough schematic...LOL I am sure it is way basic but figured to throw it in.

 

http://i32.photobucket.com/albums/d42/Gypsyfingers/Picture3-4.png

 

In V1 try to find an Ei long smooth plate 12AX7/ECC83/7025. They are the brightest and most articulate 12AX7s out there. They are very much like a Telefunken (made on the original Telefunken tooling actually) and can go microphonic easily at times but are much less pricy than a Telefunken.

 

That is the best start and if you do not hear a noticible improvement then it is the character of the amp.

 

If there are any Sovtek WA or WC in any preamp position replace them with just about anything else as they are dark. The 12AX7EH and 12AX7 Tung Sol reissues are great replacements for the Sovteks.

 

 

 

 

[Fumblyfingers]

Thanks Myles.

 

Does this apply to me?

 

" Preamplifier tubes are also used to drive the power tubes. When used in this application, a 12AX7 will produce a more distorted tone than a 12AT7, which produces a clearer, sweeter sound. A 12AU7 is even cleaner and brighter than a 12AT7, giving more definition to the sound."

 

I will do as you said though and try to find an Ei long smooth plate 12AX7/ECC83/7025.....

 

I also wondered if I should upgrade the EL 84 and the other tubes? I heard they use "cheap" tubes in this amp.

 

Sorry man...I am a player, not an amp fiddler and I never took the time to research what tubes to use...I used to let others do that who I am no longer in touch with.

 

Appreciate the time.

 

 

[myles_rose]

Thanks Myles.

 

Does this apply to me?

 

" Preamplifier tubes are also used to drive the power tubes. When used in this application, a 12AX7 will produce a more distorted tone than a 12AT7, which produces a clearer, sweeter sound. A 12AU7 is even cleaner and brighter than a 12AT7, giving more definition to the sound."

 

I will do as you said though and try to find an Ei long smooth plate 12AX7/ECC83/7025.....

 

I also wondered if I should upgrade the EL 84 and the other tubes? I heard they use "cheap" tubes in this amp.

 

Sorry man...I am a player, not an amp fiddler and I never took the time to research what tubes to use...I used to let others do that who I am no longer in touch with.

 

Appreciate the time.

 

 

I am not sure if it applies to you but it is in line with the way things are generally.

 

 

[Pick Punch]

I have an AC-60 Roland and I play it with my Ovation Celebrity but I can not seem to get a nice tone out of this thing. I though it was just acoustics of my guitar room but I don't think so. Any suggestions as to a couple settings on this thing with my ovation?

[myles_rose]

I have an AC-60 Roland and I play it with my Ovation Celebrity but I can not seem to get a nice tone out of this thing. I though it was just acoustics of my guitar room but I don't think so. Any suggestions as to a couple settings on this thing with my ovation?

 

I really cannot suggest "settings" .... your rig is what it is so to speak and in the end it is all your own personal taste and preference.

 

 

[Zephyr]

Myles, I've been wondering for a while when a tube is said to have undergone the "Black Sable" process if it is really better off.

 

http://tubedepot.com/bsct.html

 

Do you think this a marketing scheme, or is it really worth the extra dough...?

[myles_rose]

Myles, I've been wondering for a while when a tube is said to have undergone the "Black Sable" process if it is really better off.

 

http://tubedepot.com/bsct.html

 

Do you think this a marketing scheme, or is it really worth the extra dough...?

 

 

From my own personal observations and tests over the years .... yes ... this cryo stuff has been done for years .... I have found no difference other than shorter tube life due to metal and micas that have lost their ability to expand and contract as much as before the grain alignment process side effect of cryo treating.

 

But .... that is my personal take on things .... maybe others have different experience and I am happy to hear anything that anybody with a different take on things would like to post in reply to what I have said here.

 

Bear in mind that I was trained in the U.S. Navy as a structural mechanic and have a bit of understanding in regard to processing of metals and other materials and what happens to them in very cold temperatures. A tennis ball is much like mica in some aspects. Drop one in liquid nitrogen and then let it thaw out. Does it still bounce like the original? Nope.

 

Do the mica supports or spring finger supports that keep the plate structure in proper temsion with the bottle? Grid wires retain their tension as not to slip as easily on the grid posts? Not in my own experience.

 

Sonically I see nothing in the traces. Reliability for me on the road was less. Reliability off the road was lower as well.

 

If you read what the claims of folks on the website say, a lot of the stuff is used in audio gear vs guitar amps and audio gear sits on a table. I did not take too long to read what was said but nobody seemed to address reliability in amps that travel or were known names from touring groups or acts on the road.

 

 

 

 

[darkoracle]

Hi, I got a new EL34 power tube pair, and on each box, they have labels that says Gm: 5630 on one, and 5580 on the other.

 

I'm curious to know what those mean.

 

Thanks

[myles_rose]

Hi, I got a new EL34 power tube pair, and on each box, they have labels that says Gm: 5630 on one, and 5580 on the other.

 

I'm curious to know what those mean.

 

Thanks

 

Those are mutual conductance numbers. Some folks use that to match rather than plate current or in addition to plate current. This looks to be a nicely matched duet. But ... the actual number means little if anything to acertain the true condition of the tube as we don't know at what voltage and bias the tube was tested at and as these things change this number will vary dramatically. I typical request that all tubes are tested at RCA book design spec voltages and in the case of output tubes I want to know plate current. In the case of preamp tubes I want to know plate current, transconductance and plate resistance so I can calculate true actual gain as most tubes made today are typically 20%+ below spec on gain.

 

 

 

 

 

 

[si1983]

Hi Myles

 

I have a Marshall JVM 410H and i'm looking at revalving after a recent unsuccesful revalve (5x ECC83EH/SOV-CRYO's & 4x Harma EL34-CRYO's). I want to keep the Harma's as i feel they work well and don't affect the overall tone too much compared with the preamp valves.

 

I hope im not insulting your knowledge by giving you each valves purpose in this amp ;0):

 

V1, V2 gain stages, V1A, V2B are used in all modes, the rest is switched in/out depending on the mode.

V3A: tone control buffer.

V3B: channel mixer/ parallel loop send

V4A: FX mix

V4B: Reverb Mix

V5: Phase splitter

 

Im looking at spending as much as it takes to get this amp singing.

 

The EH ECC83's i feel distort too early in this amp So im looking at Mullards in V1 & V2. The rest is a mystery to me apart from maybe a GT ECC83/SAG-MPI in V5?

 

It Would be great to hear your opinion.

 

Si

 

[myles_rose]

Hi Myles

 

I have a Marshall JVM 410H and i'm looking at revalving after a recent unsuccesful revalve (5x ECC83EH/SOV-CRYO's & 4x Harma EL34-CRYO's). I want to keep the Harma's as i feel they work well and don't affect the overall tone too much compared with the preamp valves.

 

I hope im not insulting your knowledge by giving you each valves purpose in this amp ;0):

 

V1, V2 gain stages, V1A, V2B are used in all modes, the rest is switched in/out depending on the mode.

V3A: tone control buffer.

V3B: channel mixer/ parallel loop send

V4A: FX mix

V4B: Reverb Mix

V5: Phase splitter

 

Im looking at spending as much as it takes to get this amp singing.

 

The EH ECC83's i feel distort too early in this amp So im looking at Mullards in V1 & V2. The rest is a mystery to me apart from maybe a GT ECC83/SAG-MPI in V5?

 

It Would be great to hear your opinion.

 

Si

 

I stay away from the cryo stuff as I have found them to be unreliable.

 

V1 and V2 are the critical tubes in the amp and if it were my amp my own personal taste would send me the NOS rounte ... either RFTs or Brimars depending on personal taste. You can find these at www.kcanostubes.com The EHs tubes compress to fast, do not like pedals when set to higher output levels and the main fundamental tones get compressed too early in these amps and all that is left is sort of a harsh and apparent high end nature.

 

On the GT MPI .... when GT was sold to Fender in August of last year the MPI thing sort of was left in limbo. I do not know if they still do this but if they do I do not know how as I was was the one who did this and my curve tracer is now sitting with me over at 65 Amps and not at GT anymore. In the phase inverter I would use a long plate with at least 1.1mA per side of plate current. The current JJ long plate 803S is a great tube in this position in your amp.

 

On the output tubes, bias NO HIGHER than 38mA .... 36mA will maybe even be smoother. Anything over 40mA will sound harsh and tube life will be greatly reduced and the amp will run much hotter.

 

 

 

 

 

 

[mhuxtable]

Hey Myles, I'm semi-new to this forum and your service is greatly appreciated.

 

I'm a bit different than what I'm reading from most people. I play a Fender 65 reissue Twin Reverb with a Sheraton and a Strat. My thing is, I want the loudest possible sound with NO crunch. Just a completely clean, shimmering, warm sound. Are there any mods I should do to the tube setup of the amp? Everything is stock. Thanks again!

 

In V1 and V2 get some great long plate types of 12AX7 such as a 12AX7LPS. Get them from a vendor that can measure current output and make sure they are at least 1.0mA output. Also have them make sure the gain is at least 85 at 250 plate volts with a 2 volt bias.

 

On the phase inverter in V6, you want a 12AT7 that is matched with a transconductance of at least 5000 on each side.

 

On the output tubes you want some strong 6L6's ... again, from a vendor that can test these at RCA, GE, or Sylvania book spec and assure that they are matched within 10% and the current output is at least 72mA per tube. You will then bias these at 32mA. If you use a GT tube, specify a #7 rating in the 6L6GE or 6L6CHP.

 

 

Hey Myles I think Im to the point where I can do these things you recommended to me a while back. Now, do you know of anyone in NC that you would trust to measure these specs of tubes? And are there any particular brand you like? Im totally new to doing all this and Im not even gonna attempt to do this myself.

 

Basically Im gonna take the amp and print out what you said to a good amp tech and let them go to town. Any idea what a general cost would be for the tubes at those specs and then generally how much do techs charge to install them? Or is it easy enough to where I can order the tubes and put them in myself? Do you know Tim Ristau who owns Superfine Ampworks?

 

Im rambling. Sorry. But you are the man.

[myles_rose]

Hey Myles, I'm semi-new to this forum and your service is greatly appreciated.

 

I'm a bit different than what I'm reading from most people. I play a Fender 65 reissue Twin Reverb with a Sheraton and a Strat. My thing is, I want the loudest possible sound with NO crunch. Just a completely clean, shimmering, warm sound. Are there any mods I should do to the tube setup of the amp? Everything is stock. Thanks again!

 

In V1 and V2 get some great long plate types of 12AX7 such as a 12AX7LPS. Get them from a vendor that can measure current output and make sure they are at least 1.0mA output. Also have them make sure the gain is at least 85 at 250 plate volts with a 2 volt bias.

 

On the phase inverter in V6, you want a 12AT7 that is matched with a transconductance of at least 5000 on each side.

 

On the output tubes you want some strong 6L6's ... again, from a vendor that can test these at RCA, GE, or Sylvania book spec and assure that they are matched within 10% and the current output is at least 72mA per tube. You will then bias these at 32mA. If you use a GT tube, specify a #7 rating in the 6L6GE or 6L6CHP.

 

 

Hey Myles I think Im to the point where I can do these things you recommended to me a while back. Now, do you know of anyone in NC that you would trust to measure these specs of tubes? And are there any particular brand you like? Im totally new to doing all this and Im not even gonna attempt to do this myself.

 

Basically Im gonna take the amp and print out what you said to a good amp tech and let them go to town. Any idea what a general cost would be for the tubes at those specs and then generally how much do techs charge to install them? Or is it easy enough to where I can order the tubes and put them in myself? Do you know Tim Ristau who owns Superfine Ampworks?

 

Im rambling. Sorry. But you are the man.

 

On preamp tubes it is plug and play.

 

On output tubes a simple rebias should be done at the minimum bench charge. (If you were near me I'd do it for nothing)

 

As far as testing tubes ... to do it right takes equipment that most tube vendors do not have. If they have anything it is usually a simple transconductance tester and this only tests one paramater or two and one of these can be good or bad and the tube can also be great when a tester of this type says it is not good or bad when the tester shows good TC.

 

I have a list of vendors on my website that do great work and stick with those folks.

 

[si1983]

Thanks very much Myles i really appreciate your help

 

I'm living in the UK so I can find the RFT'S from watford valves but am struggling with the Brimar's? What are the tonal differences between these two valves.

 

 

also could you recomend valves for V3 and V4 for the JVM

 

thanks

 

Si

[myles_rose]

Thanks very much Myles i really appreciate your help

 

I'm living in the UK so I can find the RFT'S from watford valves but am struggling with the Brimar's? What are the tonal differences between these two valves.

 

 

also could you recomend valves for V3 and V4 for the JVM

 

thanks

 

Si

 

 

Watford Valves is a very cool supplier ... check with them as I bet they'd have Brimars but RFTs would be just as nice so maybe it's a non-problem.

 

V3 and V4 are too far removed from the tone generation stages to worry about unless they are noisy or problematic. Save your money.

[mhuxtable]

Hey Myles, I'm semi-new to this forum and your service is greatly appreciated.

 

I'm a bit different than what I'm reading from most people. I play a Fender 65 reissue Twin Reverb with a Sheraton and a Strat. My thing is, I want the loudest possible sound with NO crunch. Just a completely clean, shimmering, warm sound. Are there any mods I should do to the tube setup of the amp? Everything is stock. Thanks again!

 

In V1 and V2 get some great long plate types of 12AX7 such as a 12AX7LPS. Get them from a vendor that can measure current output and make sure they are at least 1.0mA output. Also have them make sure the gain is at least 85 at 250 plate volts with a 2 volt bias.

 

On the phase inverter in V6, you want a 12AT7 that is matched with a transconductance of at least 5000 on each side.

 

On the output tubes you want some strong 6L6's ... again, from a vendor that can test these at RCA, GE, or Sylvania book spec and assure that they are matched within 10% and the current output is at least 72mA per tube. You will then bias these at 32mA. If you use a GT tube, specify a #7 rating in the 6L6GE or 6L6CHP.

 

 

Hey Myles I think Im to the point where I can do these things you recommended to me a while back. Now, do you know of anyone in NC that you would trust to measure these specs of tubes? And are there any particular brand you like? Im totally new to doing all this and Im not even gonna attempt to do this myself.

 

Basically Im gonna take the amp and print out what you said to a good amp tech and let them go to town. Any idea what a general cost would be for the tubes at those specs and then generally how much do techs charge to install them? Or is it easy enough to where I can order the tubes and put them in myself? Do you know Tim Ristau who owns Superfine Ampworks?

 

Im rambling. Sorry. But you are the man.

 

On preamp tubes it is plug and play.

 

On output tubes a simple rebias should be done at the minimum bench charge. (If you were near me I'd do it for nothing)

 

As far as testing tubes ... to do it right takes equipment that most tube vendors do not have. If they have anything it is usually a simple transconductance tester and this only tests one paramater or two and one of these can be good or bad and the tube can also be great when a tester of this type says it is not good or bad when the tester shows good TC.

 

I have a list of vendors on my website that do great work and stick with those folks.

 

Thanks Myles. So youre saying if I order the proper preamp tubes at the specs you mentioned I can install those myself? And the output tubes I should get biased properly by a tech?

[myles_rose]

Hey Myles, I'm semi-new to this forum and your service is greatly appreciated.

 

I'm a bit different than what I'm reading from most people. I play a Fender 65 reissue Twin Reverb with a Sheraton and a Strat. My thing is, I want the loudest possible sound with NO crunch. Just a completely clean, shimmering, warm sound. Are there any mods I should do to the tube setup of the amp? Everything is stock. Thanks again!

 

In V1 and V2 get some great long plate types of 12AX7 such as a 12AX7LPS. Get them from a vendor that can measure current output and make sure they are at least 1.0mA output. Also have them make sure the gain is at least 85 at 250 plate volts with a 2 volt bias.

 

On the phase inverter in V6, you want a 12AT7 that is matched with a transconductance of at least 5000 on each side.

 

On the output tubes you want some strong 6L6's ... again, from a vendor that can test these at RCA, GE, or Sylvania book spec and assure that they are matched within 10% and the current output is at least 72mA per tube. You will then bias these at 32mA. If you use a GT tube, specify a #7 rating in the 6L6GE or 6L6CHP.

 

 

Hey Myles I think Im to the point where I can do these things you recommended to me a while back. Now, do you know of anyone in NC that you would trust to measure these specs of tubes? And are there any particular brand you like? Im totally new to doing all this and Im not even gonna attempt to do this myself.

 

Basically Im gonna take the amp and print out what you said to a good amp tech and let them go to town. Any idea what a general cost would be for the tubes at those specs and then generally how much do techs charge to install them? Or is it easy enough to where I can order the tubes and put them in myself? Do you know Tim Ristau who owns Superfine Ampworks?

 

Im rambling. Sorry. But you are the man.

 

On preamp tubes it is plug and play.

 

On output tubes a simple rebias should be done at the minimum bench charge. (If you were near me I'd do it for nothing)

 

As far as testing tubes ... to do it right takes equipment that most tube vendors do not have. If they have anything it is usually a simple transconductance tester and this only tests one paramater or two and one of these can be good or bad and the tube can also be great when a tester of this type says it is not good or bad when the tester shows good TC.

 

I have a list of vendors on my website that do great work and stick with those folks.

 

Thanks Myles. So youre saying if I order the proper preamp tubes at the specs you mentioned I can install those myself? And the output tubes I should get biased properly by a tech?

 

 

 

Preamp tubes ... do it yourself ... plug and play.

 

Output tubes .... unless you can bias the amp yourself take it to a tech.

 

 

[mhuxtable]

Hey Myles, about the Twin Reverb again. I emailed all the tube dealers on your site with your specs you mentioned to see if they can measure each of them.

 

In the meantime, I was looking up stuff about my amp and I saw something that said it has a fixed bias? What exactly does that mean and does that change the type of output tube you recommended? If my amp is "fixed bias" can you bias the tube to 32mA per tube like you said?