Feel free to ask Myles

[shoe124]

Dumb tube questions for Myles:

 

1:

Is it ok to write on these things w/sharpies so you can mark your favorite ones?

 

2:

I have a phillips ECG 5814A and 6189W...What are these? Are they 12au7's?

 

Thanks

 

Shoe

[myles_rose]

Originally posted by shoe124:

Dumb tube questions for Myles:

 

1:

Is it ok to write on these things w/sharpies so you can mark your favorite ones?

 

2:

I have a phillips ECG 5814A and 6189W...What are these? Are they 12au7's?

 

Thanks

 

Shoe

shoe124.........

 

1. Yes, it is fine to write on a tube. Some folks worry about touching them as with a halogen light bulb. This is not the case with tubes .... they are more like a common light bulb. Marks on them cause no issue.

 

2. Yes, the same as a 12AU7 for the most part, perhaps a touch different in some minor ways, but considered a direct replacement.

[WaterMan]

Myles,

 

What are your recommendations for the most realistic mic'd speaker sounding) DI boxes/ recording preamps or speaker simulators (like the Palmer). Something that does both clean and blues crunch tones would be ideal?

[sgguitarzz]

I just put in a pair of Tung Sol 5881's. They run very hot and glow almost white in color. The JJ's I had in previously run a nice orangey color and do not seem to run as hot. Is there any problem with the tube running like this?

[myles_rose]

Originally posted by WaterMan:

Myles,

 

What are your recommendations for the most realistic mic'd speaker sounding) DI boxes/ recording preamps or speaker simulators (like the Palmer). Something that does both clean and blues crunch tones would be ideal?

I prefer the Dr. Z Airbrake over other load boxes.

[myles_rose]

Originally posted by sgguitarzz:

I just put in a pair of Tung Sol 5881's. They run very hot and glow almost white in color. The JJ's I had in previously run a nice orangey color and do not seem to run as hot. Is there any problem with the tube running like this?

Check you bias RIGHT NOW. Tung Sol 5881s are small but usually much stronger than many other 6L6 family tubes. These are underbiased in your amp.

[sgguitarzz]

Thank you Myles. I will get someone to check this for me as I do not have the tools nor do I know how to do this myself. I have taken out the Tung Sols and put back the JJ's for now. I need to get a bias tool and learn.

[sgguitarzz]

Just to clarify it was the heater filament running a whitish color and not the metal plates.

[WaterMan]

Originally posted by myles111:

Originally posted by WaterMan:

Myles,

 

What are your recommendations for the most realistic mic'd speaker sounding) DI boxes/ recording preamps or speaker simulators (like the Palmer). Something that does both clean and blues crunch tones would be ideal?

I prefer the Dr. Z Airbrake over other load boxes.

I own an Airbrake, which I use to attenuate when playing thru speakers. I'm looking for a DI or other device (simulator/preamp)that would provide good mic'd speaker simulation at various gain stages (including clean) for recording without going thru speaker. Are you saying the Airbrake can act like a Palmer by plugging it's output into recording device without connecting to speaker?

[Teahead]

Hey Myles. I've ordered some NOS EL84s from Watford Valves along with a few JJ 12AX7s to use in my AC30.

 

I'm just wondering. Using this picture as a guide, which pre-amp valves relate to which particular job? http://www.voxshowroom.com/northcoast/images/products/new_amplifiers/ac30service/chart.jpg

 

Thanks for your help!

 

Tea.

[myles_rose]

Originally posted by sgguitarzz:

Just to clarify it was the heater filament running a whitish color and not the metal plates.

The heater would be OKAY, but I'd check the bias in any case.

[myles_rose]

Originally posted by Teahead:

Hey Myles. I've ordered some NOS EL84s from Watford Valves along with a few JJ 12AX7s to use in my AC30.

 

I'm just wondering. Using this picture as a guide, which pre-amp valves relate to which particular job? http://www.voxshowroom.com/northcoast/images/products/new_amplifiers/ac30service/chart.jpg

 

Thanks for your help!

 

Tea.

Teahead....

 

Hit my website and download an AC-30 schematic. This will show you what is what and you should have a print on hand.

 

Drop me a line at GT if you have questions after looking at the print.

[Teahead]

Myles, thanks once again, the schematic was a great help to me. I now feel like I almost understand what's happening in there.

 

However, I've encountered one other problem.

 

I got a matched quad of "Harma STR EL84s" from Watford Valves this morning, along with a few JJ Tesla ECC83s. I replaced the valves and switched the amp to standby, only to notice that one of the four output valves was lit very dim compared to the other three.

 

I switched the amp off and called Derek at Watford for some advice. He said I really should have checked the bias, something I know nothing about, but agreed to send a replacement as the valve never appeared to work correctly, whilst the other three were fine.

 

I had been told on a Vox forum that a bias check wouldn't be necessary, was that wrong? Could I perform this adjustment myself with the right guidelines and the right tools? Or should I leave it to a tech?

 

For the time being I have three of the Harma valves in there, with one JJ Tesla. Could this be damaging the new valves?

 

Sorry about all the questions Myles, I'd appreciate any assistance you can offer.

 

Tea.

[myles_rose]

Originally posted by Teahead:

Myles, thanks once again, the schematic was a great help to me. I now feel like I almost understand what's happening in there.

 

However, I've encountered one other problem.

 

I got a matched quad of "Harma STR EL84s" from Watford Valves this morning, along with a few JJ Tesla ECC83s. I replaced the valves and switched the amp to standby, only to notice that one of the four output valves was lit very dim compared to the other three.

 

I switched the amp off and called Derek at Watford for some advice. He said I really should have checked the bias, something I know nothing about, but agreed to send a replacement as the valve never appeared to work correctly, whilst the other three were fine.

 

I had been told on a Vox forum that a bias check wouldn't be necessary, was that wrong? Could I perform this adjustment myself with the right guidelines and the right tools? Or should I leave it to a tech?

 

For the time being I have three of the Harma valves in there, with one JJ Tesla. Could this be damaging the new valves?

 

Sorry about all the questions Myles, I'd appreciate any assistance you can offer.

 

Tea.

Tea,

 

No problem about questions ....

 

It may be that Derek was thinking of a different amp or something. I get distracted too. Perhaps he is onto something different, I don't know.

 

BUT ... from my point of view ....

 

The AC30 is a cathode biased amp. There is no bias adjustment. Tubes in the mid range are preferred. If the bias is bad for one tube, it will be bad for all of them.

 

If you look at the print, you will see that each output tube also has two resistors. One will be a 100 ohm and the other will be generally either a 1.5k or 1.8k. Measure these and make sure one of them is not open or shorted. In the circuit they should all read the same of each of the two types. In circuit they will read differently than their values, and this is normal. Just make sure as an example, that all the 100 ohm ones read within 10% or so of each other (or even 20% is fine too).

 

This may be nothing at all. If the heater is further down in one tube than the others (will cause no problem by the way), you will not see it glow as brightly, or even may not see it at all. This is the most likely case.

 

Hope this helps a bit.

[Teahead]

Thnaks for your advice, Myles. I'll get the amp checked before I put the new quad in there. The replacement should arrive before Friday so I'll let you know what the outcome is.

 

Thanks agin, Tea.

[myles_rose]

Originally posted by Teahead:

Thnaks for your advice, Myles. I'll get the amp checked before I put the new quad in there. The replacement should arrive before Friday so I'll let you know what the outcome is.

 

Thanks agin, Tea.

Tea,

 

keep me in the loop.

[rsf1977]

Hey Myles what is the Groove Tube Model for the:

12AX7LPS SOVTEK

 

I heard these are really good tubes I'm thinking of trying 2 in my dual rect, any thoughts on that? I currently have all stock Mesa 12AX7s I had EH12AX7s but found them to become really noisy rather quickly and they were a little harsh I thought.

[myles_rose]

Originally posted by rsf1977:

Hey Myles what is the Groove Tube Model for the:

12AX7LPS SOVTEK

 

I heard these are really good tubes I'm thinking of trying 2 in my dual rect, any thoughts on that? I currently have all stock Mesa 12AX7s I had EH12AX7s but found them to become really noisy rather quickly and they were a little harsh I thought.

rsf1977............

 

The 12AX7LPS is the GT-12AX7R2.

 

The EH is the GT R3.

 

Paul Rivera also likes the R2's in many Rivera amps by the way. Different than Mesa amps but generally have the same audience for some models.

[DIAMOND DUST]

Hi Myles. I have had my UNIVALVE for a few days now, and I'm in love with this amp. I have been saving my old tubes for a long time, and a few I tried yesterday sound outstanding. One is a SYLVANIA 6CA7 with yellow writing around the base. This tube is huge, and man it makes the uni very loud and tight.

 

1. Do you know anything about the quality of this tube?

2. Does GT'S make anything similar to this besides their EL34. I want to save it for recording because it sounds so good.

 

Also I found three Mullard 12ax7's. Two with the white letters, and one with yellow writing. They, of course sound great.

 

Do the new GT 12ax7's sound close to these?

 

And last is a couple RCA 7025's with red lettering. They sound way different than the mullard's. But very sweet.

 

Do you think these are good tubes?

 

Sorry so many questions. Thank you.

[rsf1977]

Originally posted by myles111:

Originally posted by rsf1977:

Hey Myles what is the Groove Tube Model for the:

12AX7LPS SOVTEK

 

I heard these are really good tubes I'm thinking of trying 2 in my dual rect, any thoughts on that? I currently have all stock Mesa 12AX7s I had EH12AX7s but found them to become really noisy rather quickly and they were a little harsh I thought.

rsf1977............

 

The 12AX7LPS is the GT-12AX7R2.

 

The EH is the GT R3.

 

Paul Rivera also likes the R2's in many Rivera amps by the way. Different than Mesa amps but generally have the same audience for some models.

Ok then let me ask this. If you were to pick the pre amp tubes for a dual rectifier running KT66 power tubes and solid state rectifier. What would you put in it to make it sound as heavy and mean as possible (ala Hardcore/Metal). The clean channel is not a concern really.

[myles_rose]

Originally posted by DIAMOND DUST:

Hi Myles. I have had my UNIVALVE for a few days now, and I'm in love with this amp. I have been saving my old tubes for a long time, and a few I tried yesterday sound outstanding. One is a SYLVANIA 6CA7 with yellow writing around the base. This tube is huge, and man it makes the uni very loud and tight.

 

1. Do you know anything about the quality of this tube?

2. Does GT'S make anything similar to this besides their EL34. I want to save it for recording because it sounds so good.

 

Also I found three Mullard 12ax7's. Two with the white letters, and one with yellow writing. They, of course sound great.

 

Do the new GT 12ax7's sound close to these?

 

And last is a couple RCA 7025's with red lettering. They sound way different than the mullard's. But very sweet.

 

Do you think these are good tubes?

 

Sorry so many questions. Thank you.

These are all great tubes if in good condition.

 

The Mullard vs the 12AX7M ... details on my website including curves.

[myles_rose]

Originally posted by rsf1977:

Originally posted by myles111:

Originally posted by rsf1977:

Hey Myles what is the Groove Tube Model for the:

12AX7LPS SOVTEK

 

I heard these are really good tubes I'm thinking of trying 2 in my dual rect, any thoughts on that? I currently have all stock Mesa 12AX7s I had EH12AX7s but found them to become really noisy rather quickly and they were a little harsh I thought.

rsf1977............

 

The 12AX7LPS is the GT-12AX7R2.

 

The EH is the GT R3.

 

Paul Rivera also likes the R2's in many Rivera amps by the way. Different than Mesa amps but generally have the same audience for some models.

Ok then let me ask this. If you were to pick the pre amp tubes for a dual rectifier running KT66 power tubes and solid state rectifier. What would you put in it to make it sound as heavy and mean as possible (ala Hardcore/Metal). The clean channel is not a concern really.

12AX7C9 in V1 and V2 just as I do for the folks at Mesa in Hollywood .... Jay, Jimbo, and John.

[rsf1977]

12AX7C9 in V1 and V2 just as I do for the folks at Mesa in Hollywood .... Jay, Jimbo, and John.[/QB]

Ok cool! What do you put in for the other tubes besides V1 V2? By the way do you know the Groove Tube equivalent for the 12AX7C9

[KARAN]

Sir, My name is Karan from India. My Uncle is coming from the USA in April.I want him to get me a electric guitar.Could you reccomend a sub 280$ guitar and a case for me.im not great at guitaring but was inspired by a movie- School of rock and am inspired to devote more time to learning the guitar.Can you reccomend a list of all Good sub 280$ guitars and tell me if my uncle can safely get it with him from US to India without any problem?

Thank You for your help and Time

from Karan

[myles_rose]

Originally posted by rsf1977:

12AX7C9 in V1 and V2 just as I do for the folks at Mesa in Hollywood .... Jay, Jimbo, and John.

Ok cool! What do you put in for the other tubes besides V1 V2? By the way do you know the Groove Tube equivalent for the 12AX7C9[/QB]

The GT-12AX7C is the C9, it is made off GT tooling.

[TELEBOY]

hi miles

 

just bought the tube amp book

going to educate myself on

repairs upgrades etc on

my crate bv60h

 

however...not one crate schematic

in the book

 

where can i find info specific to my amp

to suppliment the tech info in the book?

 

thanks

[myles_rose]

Originally posted by TELEBOY:

hi miles

 

just bought the tube amp book

going to educate myself on

repairs upgrades etc on

my crate bv60h

 

however...not one crate schematic

in the book

 

where can i find info specific to my amp

to suppliment the tech info in the book?

 

thanks

Check the print links on my website.

[Sauce]

hey myles,

i'm currently playing through an old supro thunderbolt and i was reading some stuff the other day about power cords. i realized it might be a good idea to get mine changed, it still has the old cord on it, with two prongs. if i wanted to change it to a three-pronger how much does that generally cost and is that something i could tust the local gc guys with or where should i go for this? i've had the amp for about a year, (i love it) and i've never really done anything to it but this seemed like it might be a good idea to get taken care of. thanks a lot.

[myles_rose]

Originally posted by Sauce:

hey myles,

i'm currently playing through an old supro thunderbolt and i was reading some stuff the other day about power cords. i realized it might be a good idea to get mine changed, it still has the old cord on it, with two prongs. if i wanted to change it to a three-pronger how much does that generally cost and is that something i could tust the local gc guys with or where should i go for this? i've had the amp for about a year, (i love it) and i've never really done anything to it but this seemed like it might be a good idea to get taken care of. thanks a lot.

This is pretty fast and easy. It should be the normal minimum bench charge for a tech.

[TELEBOY]

hi miles

 

thanks for the quick respones

reguarding a schematic for

my bv60h

 

as a means of learning tube amps

here's my plan

 

to systematically go through

this amp & upgrade each of the components

which are obviously not the premium pieces

due to the modest prices of the crate amps

use it as a classroom

make myself self-sufficient/marketable

in this area...

& hopefully end up with a perty good amp

in the process

 

kinda like when i started playing

i also educated myself on the tech

skills on squires & other inexpensive

guitars before moving on to the better stuff

now i have people coming to me

wanting neck resets, fretwork etc.

 

i have your tube amp book

i will soon purchase your

bias kit w/manual as well

 

have a state of the art weller

soldering station as well as

a good digital multi meter

 

i know from reading another of your

threads reguarding the tweed amp

replications that the belton sockets

are a preferable brand for quality

construction

 

who are the other mfgs of the

components i will be needing

for this endeavor...caps etc

 

where may these component items purchased

 

any other directional hints you might

offer to expedite my learning curve

would also be greatly appreciated

 

thanks