Feel free to ask Myles

[myles_rose]

Myles-A question that I have been wondering about.

If the PI isn't part of the tone generating stage of an amp, then it would seem that any specified tube would sound just like any other tube, (balanced of course!) but changing the PI from, say, a 12ax7C to a 12AX7M or, short plate to long plate, the tone seems to change- is this an aural illusion, or does the PI indeed have an effect on overall tone? or is about how a certain tube passes current? or, am I way off base here?

 

Read this - http://www.guitaramplifierblueprinting.com/files/Phaseinverter.pdf

 

[mdrs]

Hi Myles....I bought the '64 blackface Pro, and love it. It's a very cool old amp, with a lot of character. The 15" speaker seems to give a lot of "touch response"...you can really hear and feel the pick attack. So, it seems to have worked out well.

 

I do have a question. The seller said that the amp would have a Mullard GZ34 rectifier tube, but it actually has a MV GZ34 tube.

 

Will this make any difference in the amp's tone, or function that I should know about?

 

 

What is an MV?

 

If it is an NOS GZ34 it will be fine

 

Thanks, Myles.

[davidm]

Myles,

 

When changing pre-amp tubes, should the base of the tube be flush with the tube socket if possible? Is it okay if a portion of the pins are visible? I try to push them as far I can, but am wondering if I'm using too much force and if something on the board (or elsewhere) might break. My amp is a Quiana.

 

Thanks,

 

Dave

[myles_rose]

Myles,

 

When changing pre-amp tubes, should the base of the tube be flush with the tube socket if possible? Is it okay if a portion of the pins are visible? I try to push them as far I can, but am wondering if I'm using too much force and if something on the board (or elsewhere) might break. My amp is a Quiana.

 

Thanks,

 

Dave

 

Dave,

 

Some sockets do not let the tube fully seat. This is nothing to be concerned about. As long as most of the pin length is in the socket and if there is a tube shield ... it can still go on the tube, then all is fine.

 

 

[davidm]

Myles,

 

Are gold-plated (pins) tubes significantly better that regular pins?

 

Thanks,

 

Dave

[myles_rose]

Myles,

 

Are gold-plated (pins) tubes significantly better that regular pins?

 

Thanks,

 

Dave

 

Dave,

 

The do not corrode as easily but once they are in the socket it really makes little difference.

 

Gold grids are more important.

 

 

[jross68052]

Myles,

 

I checked my bias currents on my 1996 Fender Prosonic. I measured 60ma in class A, 34 ma. in class AB, and 30 ma with the soldid state rectifier. The amp is supposed to be 30 watts class A, 50 Watts class A/B and 60 watts with the SS rectifier. Any idea why the bias current would drop with the SS rectifer? I sounds best in A/B. It breakes up too early in Class A.

 

Your response is always appreciated.

 

Joe

[myles_rose]

Myles,

 

I checked my bias currents on my 1996 Fender Prosonic. I measured 60ma in class A, 34 ma. in class AB, and 30 ma with the soldid state rectifier. The amp is supposed to be 30 watts class A, 50 Watts class A/B and 60 watts with the SS rectifier. Any idea why the bias current would drop with the SS rectifer? I sounds best in A/B. It breakes up too early in Class A.

 

Your response is always appreciated.

 

Joe

 

Joe,

 

Your bias looks to be fine. Class A (really cathode biased and not technically a class A amp .... tubes are always on so seeing 100% ID is normal. But .... in cathode bias you loose power and break up is much earlier. The benefit is nice user touch sensivity and earlier breakup.

 

The reason for the voltage drop with the SS rectifier may be a design aspect of the power supply to keep the bias in a safer range by lowering the plate voltage via other aspect of the power supply, thus, keeping things more reliable.

 

You may have more actual wattage with the SS choice. You need to look at other factors using a signal generator and looking at where the amp actually breaks up rather than simply idle dissapation.

 

Things look fine from what you said.

 

 

 

[Rhino Madness]

Hello Myles,

 

I would appreciate your tube reccommendation for a metal-face 4-input non-master volume 50 watt Marshall.

 

My typical setup is a stratocaster into an OD pedal (DOD250 or TS-808 for sustain) into the Marshall. Both channels are bridged and set to 5-6 with the mid and treble fairly high.

 

I'm using JJ ECC83S (balanced for PI) and E34L now. I'm looking for a similar tone but with added expressiveness and touch sensitivity without losing the sustain (I do mostly soloing with this setup).

 

I would really appreciate your thoughts on tubes in production for preamp, PI and power (and the suggested rating if GT tubes).

 

Best regards,

Rhino

[myles_rose]

Hello Myles,

 

I would appreciate your tube reccommendation for a metal-face 4-input non-master volume 50 watt Marshall.

 

My typical setup is a stratocaster into an OD pedal (DOD250 or TS-808 for sustain) into the Marshall. Both channels are bridged and set to 5-6 with the mid and treble fairly high.

 

I'm using JJ ECC83S (balanced for PI) and E34L now. I'm looking for a similar tone but with added expressiveness and touch sensitivity without losing the sustain (I do mostly soloing with this setup).

 

I would really appreciate your thoughts on tubes in production for preamp, PI and power (and the suggested rating if GT tubes).

 

Best regards,

Rhino

 

http://www.groovetubes.com/product.cfm?Product_ID=1737

 

http://www.groovetubes.com/product.cfm?Product_ID=2170 in a #6 rating biased at 36mA

 

I am not a fan of short plate tubes in this amp for the PI

 

 

 

 

 

 

[Rhino Madness]

Hello Myles,

 

I would appreciate your tube reccommendation for a metal-face 4-input non-master volume 50 watt Marshall.

 

My typical setup is a stratocaster into an OD pedal (DOD250 or TS-808 for sustain) into the Marshall. Both channels are bridged and set to 5-6 with the mid and treble fairly high.

 

I'm using JJ ECC83S (balanced for PI) and E34L now. I'm looking for a similar tone but with added expressiveness and touch sensitivity without losing the sustain (I do mostly soloing with this setup).

 

I would really appreciate your thoughts on tubes in production for preamp, PI and power (and the suggested rating if GT tubes).

 

Best regards,

Rhino

 

http://www.groovetubes.com/product.cfm?Product_ID=1737

 

http://www.groovetubes.com/product.cfm?Product_ID=2170 in a #6 rating biased at 36mA

 

I am not a fan of short plate tubes in this amp for the PI

 

Myles,

 

Thanks for the speedy response! Lots of interesting reading at the GT site (and I can easily spend hours on your GAB site, too)!

 

Why is the GT-ECC83-S used in V1 and V2 instead of the GT-12AX7-M in the SAG Marshall Kit? I'm not criticizing the choice but mostly wondering as both are individually priced the same but the 12AX7-M is described with lots of superlatives.

 

Thanks,

Rhino

[myles_rose]

Hello Myles,

 

I would appreciate your tube reccommendation for a metal-face 4-input non-master volume 50 watt Marshall.

 

My typical setup is a stratocaster into an OD pedal (DOD250 or TS-808 for sustain) into the Marshall. Both channels are bridged and set to 5-6 with the mid and treble fairly high.

 

I'm using JJ ECC83S (balanced for PI) and E34L now. I'm looking for a similar tone but with added expressiveness and touch sensitivity without losing the sustain (I do mostly soloing with this setup).

 

I would really appreciate your thoughts on tubes in production for preamp, PI and power (and the suggested rating if GT tubes).

 

Best regards,

Rhino

 

http://www.groovetubes.com/product.cfm?Product_ID=1737

 

http://www.groovetubes.com/product.cfm?Product_ID=2170 in a #6 rating biased at 36mA

 

I am not a fan of short plate tubes in this amp for the PI

 

Myles,

 

Thanks for the speedy response! Lots of interesting reading at the GT site (and I can easily spend hours on your GAB site, too)!

 

Why is the GT-ECC83-S used in V1 and V2 instead of the GT-12AX7-M in the SAG Marshall Kit? I'm not criticizing the choice but mostly wondering as both are individually priced the same but the 12AX7-M is described with lots of superlatives.

 

Thanks,

Rhino

 

 

The M is not as gainy as the ECC83S. I like the M in V3 or the PI slot as this is picked for current while the gain stage two tubes are picked specifically for true gain .... not just something like transconductance or other factors that can be measured on conventional tube testers.

 

The cost of the tube was not a factor .... it was a matter of selecting the tubes that had the proper characteristics.

 

As a side note .... for folks using the VTV tube tester that has a scale marked "gain" .... it is NOT a true gain scale or even close. It gives an indication of tube condition but not gain, current output, plate resistance, transconductance, etc. In fact, the meter could have been labelled "pies", or "bugs" or "limit units" or have a scale that went from strawberry-vanilla-chocolate.

 

I have seen tubes that measure a "gain" of 110 on this unit where the actual gain of the tube was less than 80 in reality.

 

Still ... it is a nice device to check for noisy tubes and balance.

 

 

[Rhino Madness]

The M is not as gainy as the ECC83S. I like the M in V3 or the PI slot as this is picked for current while the gain stage two tubes are picked specifically for true gain .... not just something like transconductance or other factors that can be measured on conventional tube testers.

 

The cost of the tube was not a factor .... it was a matter of selecting the tubes that had the proper characteristics.

That makes sense. I thought maybe the color or richness imparted by the 12AX7-M could have been more rewarding but I don't have any experience with them as you guys do. Thanks for your expertise !

 

As a side note .... for folks using the VTV tube tester that has a scale marked "gain" .... it is NOT a true gain scale or even close. It gives an indication of tube condition but not gain, current output, plate resistance, transconductance, etc. In fact, the meter could have been labelled "pies", or "bugs" or "limit units" or have a scale that went from strawberry-vanilla-chocolate.

LOL! :grin: Useful info and funnily put to words!

 

I have seen tubes that measure a "gain" of 110 on this unit where the actual gain of the tube was less than 80 in reality.

 

Still ... it is a nice device to check for noisy tubes and balance.

Again, thank you for your insight!

 

Best regards,

Rhino

[myles_rose]

The M is not as gainy as the ECC83S. I like the M in V3 or the PI slot as this is picked for current while the gain stage two tubes are picked specifically for true gain .... not just something like transconductance or other factors that can be measured on conventional tube testers.

 

The cost of the tube was not a factor .... it was a matter of selecting the tubes that had the proper characteristics.

That makes sense. I thought maybe the color or richness imparted by the 12AX7-M could have been more rewarding but I don't have any experience with them as you guys do. Thanks for your expertise !

 

As a side note .... for folks using the VTV tube tester that has a scale marked "gain" .... it is NOT a true gain scale or even close. It gives an indication of tube condition but not gain, current output, plate resistance, transconductance, etc. In fact, the meter could have been labelled "pies", or "bugs" or "limit units" or have a scale that went from strawberry-vanilla-chocolate.

LOL! :grin: Useful info and funnily put to words!

 

I have seen tubes that measure a "gain" of 110 on this unit where the actual gain of the tube was less than 80 in reality.

 

Still ... it is a nice device to check for noisy tubes and balance.

Again, thank you for your insight!

 

Best regards,

Rhino

 

 

The M does not have the same sort of mid bump than the short plate ECC83S has and this is the type of tube that was so common for the British tone of that era.

 

Then again ... a lot of folks love Mullards and even Telefunkens (way too bright for me) in non-master Marshalls.

 

 

[Frails]

Hi Myles! I recently purchased a Blackface Fender PA135 head. I would like to retube (and any other maintenance you'd suggest) this head as everything looks original. My question is what tubes would you recommend for me here? I am looking for cleaner than clean since I play a ton of David Gilmour chops and have duplicated the pedalboard Pete Cornish has built for him. Can I get there with this amp head? I know it's a PA head but it really has a lot of potential with a tube change IMO. For speakers, I'm running 2 X 12 with Fenders from an old 80's Twin and a Leslie cabinet with a Fender Eminence 125 Legend 12" speaker. Thanks in advance!

 

 

Frails

[myles_rose]

Hi Myles! I recently purchased a Blackface Fender PA135 head. I would like to retube (and any other maintenance you'd suggest) this head as everything looks original. My question is what tubes would you recommend for me here? I am looking for cleaner than clean since I play a ton of David Gilmour chops and have duplicated the pedalboard Pete Cornish has built for him. Can I get there with this amp head? I know it's a PA head but it really has a lot of potential with a tube change IMO. For speakers, I'm running 2 X 12 with Fenders from an old 80's Twin and a Leslie cabinet with a Fender Eminence 125 Legend 12" speaker. Thanks in advance!

 

 

Frails

 

 

Sorry ... can't help you on this one as I have never used or been inside of one of these PA heads from Fender. I have not seen one used.

 

 

[Frails]

Thanks for the quick response. These heads have 4 clean channels....4 12ax7, 2 12at7, and the power section is 4 6L6s. Wired very close to the Twin and made in the late 70's, but without the drive channel. Footswitchable reverb. Having said that, would you have any input? In other words, what tubes do you recommend for Twins? Thanks!

 

[myles_rose]

Thanks for the quick response. These heads have 4 clean channels....4 12ax7, 2 12at7, and the power section is 4 6L6s. Wired very close to the Twin and made in the late 70's, but without the drive channel. Footswitchable reverb. Having said that, would you have any input? In other words, what tubes do you recommend for Twins? Thanks!

 

 

6L6GE in a #5-6 rating biased at 32mA - http://www.groovetubes.com/product.cfm?Product_ID=1714

 

On the front end, the main gain and tone stage would be personal preference.

 

 

[DC Ross]

Hey Myles, I've got a Rivera Knucklehead Reverb and a question.

I'm not sure if you're familiar with this specific head, but it's a 3 channel with 4x EL34s and the following preamp tube layout (from Richard's Rivera Amplifier Page:

 

V1 - First Gain Stage

V2 - Second Gain Stage for British & High Gain Channel

V3 - Final Gain Stage for American & British Channel, Third Gain Stage for High Gain Channel

V4 - Final Gain Stage for High Gain Channel, Effects Loop, & Reverb

V5 - Phase Inverter

 

Now for the question/problem: The second ("British") channel is seriously compressed sounding -- to the point that tapping on the body or bridge is almost the same volume as hitting an open chord. Any suggestions?

 

Thanks!

[myles_rose]

Hey Myles, I've got a Rivera Knucklehead Reverb and a question.

I'm not sure if you're familiar with this specific head, but it's a 3 channel with 4x EL34s and the following preamp tube layout (from Richard's Rivera Amplifier Page:

V1 - First Gain Stage

V2 - Second Gain Stage for British & High Gain Channel

V3 - Final Gain Stage for American & British Channel, Third Gain Stage for High Gain Channel

V4 - Final Gain Stage for High Gain Channel, Effects Loop, & Reverb

V5 - Phase Inverter

 

Now for the question/problem: The second ("British") channel is seriously compressed sounding -- to the point that tapping on the body or bridge is almost the same volume as hitting an open chord. Any suggestions?

 

Thanks!

 

One big mistake that many people make is reading tube layout descriptions such as the above and thinking that certain tubes are only used for certain channels. Wrong.

 

The heart of the amp is V1 ... and everything is driven by V1. Each channel then has it's own voicing.

 

You need to check V1, V2 and make sure they are of proper spec and very few tubes today are so get as close as possible.

 

Also ... try an ECC83S in v1 and V2. Great in that amp for my taste.

 

 

[Frails]

Thank you, Myles!

[myles_rose]

Thank you, Myles!

 

You are quite welcome

 

 

[Trucks]

Hey Myles, im hoping this is a relatively simple question... Do tubes last longer in a Class B amp than they would in a Class A amp? As I understand it, Class A keeps the tubes on the entire time, but im not sure if that is going to wear them out faster, or keep them going longer due to keeping them at a consistent temp.

 

Or is the question illogical with far too many factors to consider? :-)

[myles_rose]

Hey Myles, im hoping this is a relatively simple question... Do tubes last longer in a Class B amp than they would in a Class A amp? As I understand it, Class A keeps the tubes on the entire time, but im not sure if that is going to wear them out faster, or keep them going longer due to keeping them at a consistent temp.

 

Or is the question illogical with far too many factors to consider? :-)

 

 

Tubes have a much shorter life in cathode biased amps. Many people refer to these as Class A.

 

Tubes have a longer life (all things being equal) if they are grid biased, that is, what people refer to as Class AB amps.

 

Class B is not used in the audio bizz in guitar amps or hifi amps.

 

 

[Trucks]

Thanks for clearing that up Myles! :-) I am looking into getting my first tube amp, was looking at Class A, so at least now I know im gonna be changing out tubes a little more frequently! (although still not too often Id hope! haha)

 

Cheers again

[DC Ross]

One big mistake that many people make is reading tube layout descriptions such as the above and thinking that certain tubes are only used for certain channels. Wrong.

 

The heart of the amp is V1 ... and everything is driven by V1. Each channel then has it's own voicing.

 

You need to check V1, V2 and make sure they are of proper spec and very few tubes today are so get as close as possible.

 

Also ... try an ECC83S in v1 and V2. Great in that amp for my taste.

 

 

Thanks, Myles. I have GT Mullard clones in V1 and V2 right now. I put them in there hoping they would fix my issue, but to no avail -- the 'compression' seems just as bad as before.

[Hardtail]

Myles,

 

On my Hot Rod Deluxe, I'm getting this horrible "warbling" sound when switching to my gain channels. The speed and intensity change as I adjust the "gain" knob.

 

Is this a bad tube problem or is something else amiss here?

 

My clean channel sounds fine... for now.

 

Thanks!

 

[myles_rose]

Myles,

 

On my Hot Rod Deluxe, I'm getting this horrible "warbling" sound when switching to my gain channels. The speed and intensity change as I adjust the "gain" knob.

 

Is this a bad tube problem or is something else amiss here?

 

My clean channel sounds fine... for now.

 

Thanks!

 

 

Take the amp to a tech. There are a lot of solid state components in these amps ... even the reverb is NOT tube driven. It can be many things.

 

 

[myles_rose]

One big mistake that many people make is reading tube layout descriptions such as the above and thinking that certain tubes are only used for certain channels. Wrong.

 

The heart of the amp is V1 ... and everything is driven by V1. Each channel then has it's own voicing.

 

You need to check V1, V2 and make sure they are of proper spec and very few tubes today are so get as close as possible.

 

Also ... try an ECC83S in v1 and V2. Great in that amp for my taste.

 

 

Thanks, Myles. I have GT Mullard clones in V1 and V2 right now. I put them in there hoping they would fix my issue, but to no avail -- the 'compression' seems just as bad as before.

 

 

Seems like it is just the nature of the amp.

 

[Hardtail]

Myles,

 

On my Hot Rod Deluxe, I'm getting this horrible "warbling" sound when switching to my gain channels. The speed and intensity change as I adjust the "gain" knob.

 

Is this a bad tube problem or is something else amiss here?

 

My clean channel sounds fine... for now.

 

Thanks!

 

 

Take the amp to a tech. There are a lot of solid state components in these amps ... even the reverb is NOT tube driven. It can be many things.

 

 

Thanks! I'll do that.