Feel free to ask Myles

[myles_rose]

Yes, the cords are all good, and I had the tubes in a VJ head and they worked fine.

Thanks

Anthony

 

Check all the voltages and run the amp to a different speaker.

[Junior 1]

Thanks Myles. Happy Holidays.

Anthony

[ArkAmps]

Hey Myles, I didn't know you were hangin' out here!

are you by chance going to be at the NY Amp Show in May?

 

Hope to see ya there!

 

Bill C

[myles_rose]

Hey Myles, I didn't know you were hangin' out here!

are you by chance going to be at the NY Amp Show in May?

 

Hope to see ya there!

 

Bill C

 

Generally only the L.A. show as it is too busy in the summer / mid year to be able to run off even for a few days.

 

 

[Gifthorse]

Myles you look hot in this picture, I didn't know you were Blonde heh. Happy Holidays!

[Virtual Jim]

Hi Miles.

 

I have a Laney AOR Pro Tube Lead 100W head from the 80s. I bought it a couple years ago and used in a lot until Fall 06 when I moved cross-country (head traveled with me in my car). Since then I've used it intermittently. Today when I decided to fire it up as a pseudo-xmas-present-to-myself, I turned it on like normal, except there was an insane amount of hiss. The amp works and sounds fine otherwise, except the master volume knob did not work. I immediately turned the amp off; the tubes were seriously hot. I tried inserting a cable into all the plugs on the back, especially the FX loop and tried again. Same result as before. Tried both channels, same result as before. Do you have any idea of what's going on? I haven't tried pulling the tubes and reinserting them yet.

 

Thanks.

Jim

[Doros]

Hi Myles,

 

I recently moved, and have been irritated by radio noise coming from my amp (a Marshall MG30DFX) ever since. It happens whether or not a guitar is plugged in, and seems to be louder if I add pedals. It's louder in some rooms than others, and doesn't seem to change based on other equipment that is plugged in or turned on (including light switches). I have tried several different cables (all cheap cables), and I get interference on all of them except 6 inch pedal connectors. How can I get rid of this radio noise?

 

Thanks.

[myles_rose]

Hi Miles.

 

I have a Laney AOR Pro Tube Lead 100W head from the 80s. I bought it a couple years ago and used in a lot until Fall 06 when I moved cross-country (head traveled with me in my car). Since then I've used it intermittently. Today when I decided to fire it up as a pseudo-xmas-present-to-myself, I turned it on like normal, except there was an insane amount of hiss. The amp works and sounds fine otherwise, except the master volume knob did not work. I immediately turned the amp off; the tubes were seriously hot. I tried inserting a cable into all the plugs on the back, especially the FX loop and tried again. Same result as before. Tried both channels, same result as before. Do you have any idea of what's going on? I haven't tried pulling the tubes and reinserting them yet.

 

Thanks.

Jim

 

Jim,

 

This could be many things. Start by checking plate voltage, screen voltage and bias voltage and assure it is within spec.

 

 

[myles_rose]

Hi Myles,

 

I recently moved, and have been irritated by radio noise coming from my amp (a Marshall MG30DFX) ever since. It happens whether or not a guitar is plugged in, and seems to be louder if I add pedals. It's louder in some rooms than others, and doesn't seem to change based on other equipment that is plugged in or turned on (including light switches). I have tried several different cables (all cheap cables), and I get interference on all of them except 6 inch pedal connectors. How can I get rid of this radio noise?

 

Thanks.

 

It sounds as if you place has a bad ground. You need to get that resolved as it can also cause other issues outside of just amp issues.

 

 

[nath1142]

any chance you could tell me want year gibson stop puting p-90 pick ups in gibson melody makers?

[The Big G]

hi Myles

Hope you can help, I have a Fender twin 65 re-issue and I would like to know about the valves and bias on the amp.

Firstly i know the valves are a couple of years old but still sounding good, should i be looking to change them? If i do change all 4 6L6's do I have to then get the amp re-biased?

Can I do the bias or is this an amp techs domain?

many thanks

Graham

[myles_rose]

any chance you could tell me want year gibson stop puting p-90 pick ups in gibson melody makers?

 

I don't know. I am not much of a source of info on guitars. Look at a Gibson Book or post this question in the general topics on its own.

[myles_rose]

hi Myles

Hope you can help, I have a Fender twin 65 re-issue and I would like to know about the valves and bias on the amp.

Firstly i know the valves are a couple of years old but still sounding good, should i be looking to change them? If i do change all 4 6L6's do I have to then get the amp re-biased?

Can I do the bias or is this an amp techs domain?

many thanks

Graham

 

Graham,

 

Preamp tubes last for many years, decades at times.

 

Output tubes are a different story. If you have a bias tool or bias probe then biasing the amp is pretty fast and easy. On your amp it is less than 5 minutes and the chassis does not even have to be pulled.

 

I set the bias about 30mA using one of these sorts of tools.

 

Preamp tube changes need no bias or any adjustment ... plug and play.

 

One of my favorite output tubes in the Twin Reverb, original or reissue, is the REAL winged C Svetlana. ARS Electronics usually has these in stock and although I am unsure of the price they are a great deal and their testing and matching is first rate, plus, they sell direct to the end user as well as having their commercial division. They are at www.arselectronics.com as a side note. They are also a pretty cool source for a lot of things other than tubes.

 

The real Svetlana is NOT the same as tubes with the Svetlana name or SED name as those are not from the actual Svetlana factory but from the Sovtek factory. The real Svet (winged C logo) is a copy of the famed Sylvania STR387 which WAS the tube used originally in the Fender BF twin reverb.

 

 

 

 

 

[The Big G]

hi Myles

Hope you can help, I have a Fender twin 65 re-issue and I would like to know about the valves and bias on the amp.

Firstly i know the valves are a couple of years old but still sounding good, should i be looking to change them? If i do change all 4 6L6's do I have to then get the amp re-biased?

Can I do the bias or is this an amp techs domain?

many thanks

Graham

 

Graham,

 

Preamp tubes last for many years, decades at times.

 

Output tubes are a different story. If you have a bias tool or bias probe then biasing the amp is pretty fast and easy. On your amp it is less than 5 minutes and the chassis does not even have to be pulled.

 

I set the bias about 30mA using one of these sorts of tools.

 

Preamp tube changes need no bias or any adjustment ... plug and play.

 

One of my favorite output tubes in the Twin Reverb, original or reissue, is the REAL winged C Svetlana. ARS Electronics usually has these in stock and although I am unsure of the price they are a great deal and their testing and matching is first rate, plus, they sell direct to the end user as well as having their commercial division. They are at www.arselectronics.com as a side note. They are also a pretty cool source for a lot of things other than tubes.

 

The real Svetlana is NOT the same as tubes with the Svetlana name or SED name as those are not from the actual Svetlana factory but from the Sovtek factory. The real Svet (winged C logo) is a copy of the famed Sylvania STR387 which WAS the tube used originally in the Fender BF twin reverb.

 

 

 

 

Myles

many thanks and thanks for the tube shout I will give them a try, but thanks again for your help

G

[Bluesape]

Hey Myles - Happy New Year!

 

Ever heard of Lifco(?) tube amps? I think they were from Montreal, maybe in the 70's. I saw a small one locally, and I'm curious.

[Junior 1]

Hi Myles and Happy New Year!

I've been looking at the new Fender XD tube amps. They have preamp and power tubes, yet they are refered to as hybrids. There are 2 models that have a bunch of digital effects and are 5 and 15 watts. Are these true tube amps? Are the preamps tube driven?

Thanks

Anthony

[myles_rose]

Hey Myles - Happy New Year!

 

Ever heard of Lifco(?) tube amps? I think they were from Montreal, maybe in the 70's. I saw a small one locally, and I'm curious.

 

Nope ... never heard of them. Then again, there is a lot of stuff I am not aware of.

 

 

[myles_rose]

Hi Myles and Happy New Year!

I've been looking at the new Fender XD tube amps. They have preamp and power tubes, yet they are refered to as hybrids. There are 2 models that have a bunch of digital effects and are 5 and 15 watts. Are these true tube amps? Are the preamps tube driven?

Thanks

Anthony

 

I have not heard of the XD and cannot even find it on the Fender website.

[Junior 1]

Hi Myles,

They are called the Fender Champ XD and Super Champ XD. They are on the Fender site.

Thanks

Anthony

[myles_rose]

Hi Myles,

They are called the Fender Champ XD and Super Champ XD. They are on the Fender site.

Thanks

Anthony

 

I have not seen inside these amps or played them.

[blizzard_rw]

Hi Myles,

Some one on the talk bass forum told me to contact you. I have a Traynor YBA-2B. It has not been played for about 6 or 7 years. Now when it is played, the volume is very quiet and the bass notes distort very easily. When I stopped playing it 6 or 7 years ago it had much more volume. I origionaly stopped playing it because it started to sound like crap(distortion in the low notes and you always sound kind of flat). Could the tubes be the problem? Do you have another idea as to what it could be. it has 2 sets tubes: 2 12AX7a phillips (i think these are the pre amp set) and 2 6BQ5 sylvania (I think these are the power tubes). If it is the tubes, is it as simple as pulling the old ones out and putting the new ones in? It seems like everybody has a different opinion on what I should do, if I should replace the tubes, or with what I should replace them with. Thanks for your help. By the way, the amp fell over real hard one time, but this was before the problems started.

 

Ryan Blizzard

[myles_rose]

Hi Myles,

Some one on the talk bass forum told me to contact you. I have a Traynor YBA-2B. It has not been played for about 6 or 7 years. Now when it is played, the volume is very quiet and the bass notes distort very easily. When I stopped playing it 6 or 7 years ago it had much more volume. I origionaly stopped playing it because it started to sound like crap(distortion in the low notes and you always sound kind of flat). Could the tubes be the problem? Do you have another idea as to what it could be. it has 2 sets tubes: 2 12AX7a phillips (i think these are the pre amp set) and 2 6BQ5 sylvania (I think these are the power tubes). If it is the tubes, is it as simple as pulling the old ones out and putting the new ones in? It seems like everybody has a different opinion on what I should do, if I should replace the tubes, or with what I should replace them with. Thanks for your help. By the way, the amp fell over real hard one time, but this was before the problems started.

 

Ryan Blizzard

 

I would have the amp checked out since it fell hard.

 

The output tubes should be replaced if they have not been for years. Use the EL84S in a #5-6 rating and it is a plug and play situation to change the tubes.

 

 

[Zephyr]

Hey Myles,

 

i've recently been researching this amp: http://www.musiciansfriend.com/product/Marshall-1974X-Handwired-18W-1x12-Combo-Amp?sku=482706

 

And I was wondering, do you know anything about its circuit or anything special? If so, could you tell me about it?

[myles_rose]

Hey Myles,

 

i've recently been researching this amp: http://www.musiciansfriend.com/product/Marshall-1974X-Handwired-18W-1x12-Combo-Amp?sku=482706

 

And I was wondering, do you know anything about its circuit or anything special? If so, could you tell me about it?

 

Great amps .... prints are probably on my GAB website and there is a ton of history out there on the net on these amps.

 

 

[Zephyr]

Thanks Myles, unfortunately, that one design isn't on you site. Oh well, it's still a great resource

 

I've also tried to google "Marshall 1974X circuit" and came up with sales pitches. What i meant by my previous post is, what are some of the characteristics of that amp? the most basic I know of is that Marshall's sound darker than Fender's.

 

One last question, how does "jumping" channels work, and what would the resulting jump do tonally?

[myles_rose]

Thanks Myles, unfortunately, that one design isn't on you site. Oh well, it's still a great resource

 

I've also tried to google "Marshall 1974X circuit" and came up with sales pitches. What i meant by my previous post is, what are some of the characteristics of that amp? the most basic I know of is that Marshall's sound darker than Fender's.

 

One last question, how does "jumping" channels work, and what would the resulting jump do tonally?

 

Go here:

 

http://www.drtube.com/marshall.htm#JMP18W

 

On jumpering ... the 50 and 100 watter four input Marshalls only use half of V1 for each set of inputs... the normal and bright inputs. When you jumper them you are sending the result of both sides of V1 on to V2 rather than just half of the tube. This also allows the use of both volume controls to balance the tone of both input stages of the amp for a bit more tonal control.

 

You cannot do this on a Fender black face amp though as the two sides (normal and vibrato) will be out of phase and there are some other issues as well.

 

 

[nath1142]

k thanks

[steve f]

Myles,

 

I have a tube tester that measures transconductance, which I understand is related to current output vs voltage input. Would a tube measuring higher in current output be better in the phase inverter position versus one of average output? I know that there's probably more to it than that, but just trying to keep it basic.

 

My tester was professionally refurbished and recalibrated a few years back (by the late Chris Haedt), and it's the best I'm going to be able to do since I can't afford real professional gear. I'm just trying to get an idea of what tubes to use in what position relative to each other, not do professional grading etc.

[myles_rose]

Myles,

 

I have a tube tester that measures transconductance, which I understand is related to current output vs voltage input. Would a tube measuring higher in current output be better in the phase inverter position versus one of average output? I know that there's probably more to it than that, but just trying to keep it basic.

 

My tester was professionally refurbished and recalibrated a few years back (by the late Chris Haedt), and it's the best I'm going to be able to do since I can't afford real professional gear. I'm just trying to get an idea of what tubes to use in what position relative to each other, not do professional grading etc.

 

I prefer tubes that come closer to proper current than on the low side for PI use.

 

 

[Caevan O’Shite]

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?