Feel free to ask Myles

[johnny5]

Originally posted by myles111:

Originally posted by johnny5:

i have Reverend Hellhound combo (2 6L6's, 60W, 1X12) that has Electro Harmonics 6L6's in it. i have read that these tubes are not very good. and in listening i notice that when these suckers are pushed, they get less and less sweet. almost flabby. i was looking the groove tubes site at the CB's looks like i can get a little more power tube distortion out of those.

 

any thoughts or recomendations?

johnny5 ...

 

The CB's are Chinese with a softer vacuum, but do have more mids than the EH's .... most 6L6 tube actually do.

 

In your amp my favorite tube is the KT-66HP, that is also now one of the least expensive in the GT line as we dropped price from $85 a duet to $60.00 a duet ( $5.00 cheaper than the Chinese KT-66 we also carry with the price drop now ).

 

I like these with a #5 rating in your amp and in the Dr. Z Route 66 amp (that was designed around this particular tube if you check with them). I also use this in a JTM-45 and a GT Solo 45.

 

Myles

why are the KT-66HP's your favorate in the hellhound? i'm looking for good rock / blues / rockin blues tone (FYI).

[myles_rose]

Originally posted by johnny5:

Originally posted by myles111:

Originally posted by johnny5:

i have Reverend Hellhound combo (2 6L6's, 60W, 1X12) that has Electro Harmonics 6L6's in it. i have read that these tubes are not very good. and in listening i notice that when these suckers are pushed, they get less and less sweet. almost flabby. i was looking the groove tubes site at the CB's looks like i can get a little more power tube distortion out of those.

 

any thoughts or recomendations?

johnny5 ...

 

The CB's are Chinese with a softer vacuum, but do have more mids than the EH's .... most 6L6 tube actually do.

 

In your amp my favorite tube is the KT-66HP, that is also now one of the least expensive in the GT line as we dropped price from $85 a duet to $60.00 a duet ( $5.00 cheaper than the Chinese KT-66 we also carry with the price drop now ).

 

I like these with a #5 rating in your amp and in the Dr. Z Route 66 amp (that was designed around this particular tube if you check with them). I also use this in a JTM-45 and a GT Solo 45.

 

Myles

why are the KT-66HP's your favorate in the hellhound? i'm looking for good rock / blues / rockin blues tone (FYI).

Its just personal preference.

 

Myles

[Dave da Dude]

Myles, This two questions.

 

1) What is bias? I'm an (Mechanical) Engineer and I may be a little weak on this, but as far as I know the only three things that matter to an electrical device are Volts, Amps and Resistance. Which is bias? Are you (generically/plurally) adjusting the resistance to make the voltage or amperage correct?

 

If so, what do you look for. I have a wealth of equipment available to me and I'm fairly good at this kind of "stuff". Can I do it myself?

 

2)This is a repeat and I already know that your opinion is it's too complicated. BUT, if I want to do it anyway, is there any HARM in switching "hot" tubes (via circuit) to change from EL34's to 6L6's?

 

Thanks for any help you can offer. You're a wealth of knowledge and feel very fortunate to find someone as knowledgeable as you that is willing to help ignoramuses like me that need help.

 

Thanks, Dave.

[myles_rose]

Originally posted by Dave th Dude:

Myles, This two questions.

 

1) What is bias? I'm an (Mechanical) Engineer and I may be a little weak on this, but as far as I know the only three things that matter to an electrical device are Volts, Amps and Resistance. Which is bias? Are you (generically/plurally) adjusting the resistance to make the voltage or amperage correct?

 

If so, what do you look for. I have a wealth of equipment available to me and I'm fairly good at this kind of "stuff". Can I do it myself?

 

2)This is a repeat and I already know that your opinion is it's too complicated. BUT, if I want to do it anyway, is there any HARM in switching "hot" tubes (via circuit) to change from EL34's to 6L6's?

 

Thanks for any help you can offer. You're a wealth of knowledge and feel very fortunate to find someone as knowledgeable as you that is willing to help ignoramuses like me that need help.

 

Thanks, Dave.

Dave,

 

Take a look on my website.

 

Myles

[kirschke]

Hi Miles,

what Bias resp. Anode current-mA-do You recommend

with a B+ 435 V.

Does a PT-Fender 022798 4A/6,3V- take the extra

heater current? I have 2 12AX7 and 2 12AT 7 in the

preamp.

What did Marshall use in his original Bluesbreaker

combo?

Thanks,

Wolfgang

[kirschke]

I forgot I mean KT66 tubes,

Sorry,

Wolfgang

[steve f]

Myles,

 

Are the Groove Tubes KT-66HP considered 25watt or 30watt tubes (or something in between)? Just wondering about biasing them. I couldn't pass them up at the reduced price GT has them at.

[Razor]

I have recently purchased a mesa boogie road king. The tubes are whatever

>are stock in it.

>

>I have two groove tubes ahh.umm el 34? Well the tubes that would go into a

>mesa boogie nomad 55. I bought the tubes for that amp but never used them.

>Can I use these tubes in the mesa and will that help this lack luster amp.?

>

>I would be happpy to replace the tubes in this amp if you could advise me

>as

>to what the best solution is and where I can puchase them/what tubes?

>

>I also wish to get a 'vox ac 30 sound", and I doubt I can out of this amp?

>Can I with the univalve? This is another tasty amp I would like, but I dont

>think I can get the vox chimy sound. I have to play at lower levels, but I

>dont play live and I do mostly recording at home. Any other amps? Someone

>said a mesa boogie blue angel with a 30 watt speaker to replace the stock

>90

>watt..or laney amps., not sure of what model..

>

>Any thoughts/

>

>THe tubes for the mesa are my main question to you cause I know this is

>your

>expertise. But any help on the others would be helpful.

>thankyou

ps what do you think of top hat royals...Im thinking of getting the new ac 30 tbx HW..but way more money

[RockNRoll]

Hi Myles, I put up this post but couldn't get a response...i dunno if I'm asking the right question. Appreciate any advice you can offer.

 

I'm looking for a volume pedal and was wondering if getting a mono pedal or stereo was better? I use mainly clean and distortion sounds perhaps with some reverb, chorus, and delay...Would getting a stereo pedal offer more versatility if I decide to get a stereo effect down the road? I've heard about some power loss when using primarily mono effects with a stereo volume pedal...or is it that noticeable? I was thinking something like the Boss FV50H which is a stereo pedal which seemed to get some good user reviews and it seems a little more convenient to carry compared to those huge heavy duty volume pedals...Not sure which way to go..could use some tips..thanks!

--------------------------------------------------------------------------------

[myles_rose]

Originally posted by kirschke:

Hi Miles,

what Bias resp. Anode current-mA-do You recommend

with a B+ 435 V.

Does a PT-Fender 022798 4A/6,3V- take the extra

heater current? I have 2 12AX7 and 2 12AT 7 in the

preamp.

What did Marshall use in his original Bluesbreaker

combo?

Thanks,

Wolfgang

For the KT-66 with your plate voltage, the idle dissapation would be as follows:

 

50% 60% 70%

 

29 34 40 mA

 

I like 30-32 or so myself.

 

The original Bluesbreaker used 3 eCC83's and

two KT-66's.

 

Myles

[myles_rose]

Originally posted by steve f:

Myles,

 

Are the Groove Tubes KT-66HP considered 25watt or 30watt tubes (or something in between)? Just wondering about biasing them. I couldn't pass them up at the reduced price GT has them at.

Steve,

 

They are 25 watters, as the original GEC's.

 

The price was $85.00 a duet a few weeks ago, so yes, they are cheaper now which is nice. The reason was we made a lot more so the price per tube dropped. The non-HP version is actually more now, which is sort of strange I guess. I don't know if GT will even have all that many request in the future for those since they are more money and handle about 50 less plate volts.

 

Myles

 

Myles

[myles_rose]

Originally posted by Razor:

I have recently purchased a mesa boogie road king. The tubes are whatever

>are stock in it.

>

>I have two groove tubes ahh.umm el 34? Well the tubes that would go into a

>mesa boogie nomad 55. I bought the tubes for that amp but never used them.

>Can I use these tubes in the mesa and will that help this lack luster amp.?

>

>I would be happpy to replace the tubes in this amp if you could advise me

>as

>to what the best solution is and where I can puchase them/what tubes?

>

>I also wish to get a 'vox ac 30 sound", and I doubt I can out of this amp?

>Can I with the univalve? This is another tasty amp I would like, but I dont

>think I can get the vox chimy sound. I have to play at lower levels, but I

>dont play live and I do mostly recording at home. Any other amps? Someone

>said a mesa boogie blue angel with a 30 watt speaker to replace the stock

>90

>watt..or laney amps., not sure of what model..

>

>Any thoughts/

>

>THe tubes for the mesa are my main question to you cause I know this is

>your

>expertise. But any help on the others would be helpful.

>thankyou

ps what do you think of top hat royals...Im thinking of getting the new ac 30 tbx HW..but way more money

Razor,

 

Road King .... more knobs and switches on the back panel alone and any three of my amps have on their front panels !

 

The stock tubes are Russian or Chinese. If you tell me the STR number on the tube I can tell you. Also let me know the color code on the small label on the base.

 

There are a lot of different Groove Tubes EL-34 tubes. I would need to know which.

 

For EL-34 tubes, I prefer the:

 

http://www.groovetubes.com/product.cfm?Product_ID=1690

 

Your amp will never sound like an AC-30. Very different amps and circuits.

 

The Univalve can get the VOX sound with an ECC83 in V1, an ECC83 or 12AX7 in V2, and an EL-84 in the adaptor that THD has for the amp.

 

The Blue Angel in 33 watt mode (using its EL-84's) is very different than an AC-30. The tone stacks of the two amps are not even close.

 

The Top Hat amps are very nice.

 

The AC-30 reissues are fine too, but still one of the most difficult amps in the world to work on physically.

 

Myles

[myles_rose]

Originally posted by RockNRoll:

Hi Myles, I put up this post but couldn't get a response...i dunno if I'm asking the right question. Appreciate any advice you can offer.

 

I'm looking for a volume pedal and was wondering if getting a mono pedal or stereo was better? I use mainly clean and distortion sounds perhaps with some reverb, chorus, and delay...Would getting a stereo pedal offer more versatility if I decide to get a stereo effect down the road? I've heard about some power loss when using primarily mono effects with a stereo volume pedal...or is it that noticeable? I was thinking something like the Boss FV50H which is a stereo pedal which seemed to get some good user reviews and it seems a little more convenient to carry compared to those huge heavy duty volume pedals...Not sure which way to go..could use some tips..thanks!

--------------------------------------------------------------------------------

RockNRoll....

 

The choice of a stereo or mono pedal is pretty simple ... are you going to run into a stereo rack or not.

 

They both work well, more of a choice by model of features, price, feel, and range of travel.

 

Myles

[Razor]

Myles.

 

Re Road king/Info you need

 

In my Road King , this is what I found, and remember, I know very little about Tubes.

 

The EL 34 has a mesa engineering logo on them, and say

"Handtested in Amplifiers and computer Matched. At the bottom of the tube on a silver tabbed area it only says " 49 AC GRN "

Thats all that are on that tube that I can see.

 

Now, for the 6aL6 GC tube.

Again it says 'mesa engineering on it" and a "STR 430" on the tube itself. On the bottom silver area tab, i see a 47 AC gry. This is the same for all these four tubes.

 

Now the 5U4G tubes, which there are two, have again "mesa engineering' on them and abosolutely nothing else. The base of this tube is Brown and I can see scratched on the top metal place "inside' the tube itself, just below the glass on the very top of the tube, 10-10, if thats of any use.

 

Curious, I notice on each and every tube, a man made 'scratch' about maybe 1/4 or so inch long at the base of each tube. No real reason but they are there..

 

I do not see any color label other than the gry or silver that the writing is on ie '49 ac grn'etc.

 

The tubes I have in my possession which I have never used, bought for another amp thus sold are..

GT 34Ls. A the bottom they have a 'performance 4" and matched with a DDK on the tube, written in handwright on both.

 

What do you think of this amp myles. I am a home recordist, probably will never play live, but who knows.

 

I have bid and won a univalve on ebay.

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=893835163

 

The seller is unhappy now to sell it but he will sell it to me, but wishes also to not, if i so choose to walk away.

I'm looking for a 'vox' sound, for one thing. I like the idea of some good 'aerosmith' sounds too, edgy, with a bite to it..aka Tragically hip , will this amp provide this? and more?

 

Also looking at bidding on a top hat for the vox sound (tom petty ish or the knack sound), but if I can get mostly this sound with the univavle, great, I'll stop there. How do you feel about the univalve?

 

Last thing myles. Komet amps. I heard the samples on the net. Sounds amazing. I feel perhaps the road king is not up to this standard of the komet , how do you feel? I could sell the king and get a komet I guess is where Im headed with this.

 

Natuarlly only I can decide and my ears, but Id be very happy to hear your opinions. Im not into 'creed' or dark sounds, I love the beatles later stuff, tragically hip, queen, aerosmith, eagles, so quite diverse.

As a home recordist I need the most options with the least amount of complexity involved. I do have a pod btw...and thats ...well Im not sure what to say about that.

 

THanks myles, if I can supply you with anymore data please ask. If keeping the road king is smart, I will. btw..its RK 169 serial number.

 

THanks

[myles_rose]

Originally posted by Razor:

Myles.

 

Re Road king/Info you need

 

In my Road King , this is what I found, and remember, I know very little about Tubes.

 

The EL 34 has a mesa engineering logo on them, and say

"Handtested in Amplifiers and computer Matched. At the bottom of the tube on a silver tabbed area it only says " 49 AC GRN "

Thats all that are on that tube that I can see.

 

Now, for the 6aL6 GC tube.

Again it says 'mesa engineering on it" and a "STR 430" on the tube itself. On the bottom silver area tab, i see a 47 AC gry. This is the same for all these four tubes.

 

Now the 5U4G tubes, which there are two, have again "mesa engineering' on them and abosolutely nothing else. The base of this tube is Brown and I can see scratched on the top metal place "inside' the tube itself, just below the glass on the very top of the tube, 10-10, if thats of any use.

 

Curious, I notice on each and every tube, a man made 'scratch' about maybe 1/4 or so inch long at the base of each tube. No real reason but they are there..

 

I do not see any color label other than the gry or silver that the writing is on ie '49 ac grn'etc.

 

The tubes I have in my possession which I have never used, bought for another amp thus sold are..

GT 34Ls. A the bottom they have a 'performance 4" and matched with a DDK on the tube, written in handwright on both.

 

What do you think of this amp myles. I am a home recordist, probably will never play live, but who knows.

 

I have bid and won a univalve on ebay.

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=893835163

 

The seller is unhappy now to sell it but he will sell it to me, but wishes also to not, if i so choose to walk away.

I'm looking for a 'vox' sound, for one thing. I like the idea of some good 'aerosmith' sounds too, edgy, with a bite to it..aka Tragically hip , will this amp provide this? and more?

 

Also looking at bidding on a top hat for the vox sound (tom petty ish or the knack sound), but if I can get mostly this sound with the univavle, great, I'll stop there. How do you feel about the univalve?

 

Last thing myles. Komet amps. I heard the samples on the net. Sounds amazing. I feel perhaps the road king is not up to this standard of the komet , how do you feel? I could sell the king and get a komet I guess is where Im headed with this.

 

Natuarlly only I can decide and my ears, but Id be very happy to hear your opinions. Im not into 'creed' or dark sounds, I love the beatles later stuff, tragically hip, queen, aerosmith, eagles, so quite diverse.

As a home recordist I need the most options with the least amount of complexity involved. I do have a pod btw...and thats ...well Im not sure what to say about that.

 

THanks myles, if I can supply you with anymore data please ask. If keeping the road king is smart, I will. btw..its RK 169 serial number.

 

THanks

Razor

 

On your EL-34's they are hard to say without seeing the tube. They are probably either Chinese or Sovtek. They are in the same range as a GT #5 for the most part.

 

The 6L6 is a Sovtek 6L6B / WXT tube. Its a fine sturdy tube. The 454's were the Svetlana upgrade, but are more expensive for Mesa to buy, so they don't use as many of these.

 

My favorite tube in these amps are the 6L6S, or JJ 6L6.

 

Your Rectifiers. These are Chinese rectifiers, with a very high initial failure rate. BUT ... if they have worked for ten hours, then chances are they will hang in there for a while.

 

The scratch is from their testing, either to index the tube when the paint on their logo, or to perhaps say the tube went through their testing. It is fine. Mesa does very nice testing on their power tubes by the way.

 

The GT E34Ls that you have in #4 will work great to replace your current ones in there. The DDk are the initials of who tested the tubes. They will give you about 20% more output and headroom also, then the stock EL34 tubes.

 

On the THD ... the photos are gone, but for $710 its great, especially with the acessories.

 

Frankly, to be blunt and totally confused, I can never understand why anybody that ever bought a Univalve would ever sell it. It boggles me to try to figure that out unless it was financial issues where they were selling everything. If I ever had to raise money by selling things, my UV would go as perhaps the last item. If its a matter of not liking the tone, then that is a matter of pilot error to my thinking. Its a great recording too, live tool for more gigs than most give it credit for (15 watts class A is a LOT louder than my 25 watt Deluxe Reverb, and with a 1x12 open back cabinet, it is louder than my Marshall JTM-45 with it's 4x12 closed back cab.

 

The accessories that were included:

 

Celestion Vintage 30 1x12 speaker cabinet (8 ohm, closed back, mfg by Crate)

 

This will work fine, but if you can open the back, try that too. Vintage 30's are great with the UV.

 

THD Yellowjacket w/ JJ EL84 tube (Vox AC30 sound)

 

.... You bet ... but also BOTH versions ... Brian May AC-30/4 and the more common AC-30/6 (top boost). The tone controls on the UV are much more effective, but you can dial the amp in to be as AC-30 as you want. This is something the UV does MUCH better than our GT version of this type of amp. Those adaptors are worth about $50.00. It is ONLY for the Univalve, don't try to plug this in to a class A/B amp. THD had other Yellow Jackets for that.

 

6L6GC Mesa Boogie Tube (Fender/Boogie sound)

... a fair tube .... get a nice 6L6 ... maybe an NOS since you need only one.

 

Svetlana EL34 tube (Marshall sound)

This will be fine.

 

Electro Harmonix EH12AX7 preamp tubes (2)

Good, but get a 12AT7 for V2, and swap them around a little. An ECC83 and 7025 are also good in V1. With your EL-84, use an ECC83 in V1.

 

Manual, speaker cable, power cable.

Manual? Mine did not even have a manual, but its when they first started making them I guess.

 

The seller is unhappy now to sell it but he will sell it to me, but wishes also to not, if i so choose to walk away.

 

NO .... talk to him, keep him happy ... tell him all the other great things he can buy with that like a Fender Deluxe Reverb reissue ... or an original Silver Face Fender whatever (still great deals). I guess after thinking about it he might feel he made a bit of a mistake, but even if he sold that setup for $1200, it would still be a mistake. It's not the price ... it was a good and fair deal for each of you .... its more of like that credit card commercial .... sort of ...

 

"Marshall Plexi 1966 .... $2500 ...... Fender Tweed magic amp ..... $3500 ....... THD Univalve .... priceless"

 

Before you buy anything else, including the Top Hat (great amps by the way), play with the THD Univalve for 30 days. I still learn things about mine continually. You may find you need a lot less amps than you were using.

 

Ahhhh .... put a NOS 6L6 in there ... a NOS 12AX7 in V1, a NOS 12AT7 in V2, the high gain input but the volume turned to maybe 9 '0clock ... not much at all ... plug in a solid body P-90 guitar, and play the BLUES. (sorry ... off on a tangent)

 

Komet .... also very good amps.

 

The Road King is nowhere close to these other amps in constrution or basic tone, but you cannot compare a high volume production amp to these others, its not fair. The Road King has different uses, and has lots of knobs and setting for folks into that. They offer a lot of hardware and poundage for the buck. One of the problems today is with all the high gain amps around, folks forget about "tone". Sure these amps make great "sounds", but tone is something more complex ... details ... playability ... dynamics ... touch ... etc.

 

When you design in a lot of front end gain in the first stage (as do most folks today, because it sells a lot of amps), you loose dynamic range, and all sorts of other things as the trade off.

 

You hear about "tone" in reference to the old tweed this or that, the blackface whatever, or the old plexi Marshalls and Bluesbreaker amps. These had a lot less gain by the way than later Marshalls. You rarely here "tone" used to describe newer amps ... unless the term is sort of mis-used to my way of thinking. Maybe the amps have a great sound ... killer sound, etc., but that is different than tone.

 

There are some folks that get tone by using classis designs, such as Victoria, Matchless, Bad Cat, Carr, and a few others.

 

Then there are the folks that take classic designs, and re-engineer and redesign them such as Doug Roccaforte. His amps have touch, feel, headroom. He does not build excessive gain and noise into the front end of his designs, and thus, they are much more versitile.

 

Paul Rivera ... also a great line of versitile amps. Listen to a Quiana sometime on the clean channel (2), with its 6L6's, with the master on about 8-9 and the volume down at 4.

 

Regards,

 

Myles

[alevinthal]

Hi Myles, I have a Randall RT-30, an amp that I love, with a wonderful and unique sound, but it needs an hour to warm up, sounds great for about an hour, and then 'loses the magic' over the next hour.

 

What makes an amp do this, and what can I do to get it to 'warm-up' faster, and then stay in that great tonal zone? I have 2 old boogies (studio 22 and MKII) that act the same way.

 

I have the schematics (as .pdf files) if you are interested in seeing them.

 

-Adam-

[rsf1977]

Hey Myles, I was practicing yesterday and infrequently my amp would all of a sudden lose almost all volume and as it went down the sound got really grainy, do you know what could cause this?

 

I recently had couple weeks before had my pickup changed could it be a bad connection or something, About a month ago I switched to the Groove Tube GE-6L6s do you think it could be a bad power tube? Let me know, thanks.

[rsf1977]

Hey Myles, I was practicing yesterday and infrequently my amp (mesa Dual Rectifier 2 channel Solo Head) would all of a sudden lose almost all volume and as it went down the sound got really grainy, do you know what could cause this?

 

I recently had couple weeks before had my pickup changed could it be a bad connection or something, About a month ago I switched to the Groove Tube GE-6L6s do you think it could be a bad power tube? Let me know, thanks.

[Franknputer]

Hi Myles -

 

trivia question - ever see/hear of a single EL34 amplifier? Is there some reason this would not be possible?

 

Sorry I missed you guys at the lunch with Lee last Saturday - hope you might make it to our dinner on Tuesday?

 

Cheers!

Christopher

[myles_rose]

Originally posted by aleinthal:

Hi Myles, I have a Randall RT-30, an amp that I love, with a wonderful and unique sound, but it needs an hour to warm up, sounds great for about an hour, and then 'loses the magic' over the next hour.

 

What makes an amp do this, and what can I do to get it to 'warm-up' faster, and then stay in that great tonal zone? I have 2 old boogies (studio 22 and MKII) that act the same way.

 

I have the schematics (as .pdf files) if you are interested in seeing them.

 

-Adam-

Adam,

 

If you have three tube amps that act the same way in your place, the first thing I would do is check your AC or borrow a variac and try one of the amps on there for a bit.

 

Myles

[myles_rose]

Originally posted by rsf1977:

Hey Myles, I was practicing yesterday and infrequently my amp (mesa Dual Rectifier 2 channel Solo Head) would all of a sudden lose almost all volume and as it went down the sound got really grainy, do you know what could cause this?

 

I recently had couple weeks before had my pickup changed could it be a bad connection or something, About a month ago I switched to the Groove Tube GE-6L6s do you think it could be a bad power tube? Let me know, thanks.

rsf1977...

 

It could be a few things. On your rectifier, switch to the solid state setting when this happens and see if there is a change.

 

It very well could be one of your power tubes, they are fragile in shipping and that is why GT has their warranty.

 

If you have the set that came out of the amp, try them, and if they don't do the same thing, then I'd suspect one of the tubes as a possibility if once the GE tube goes off its prime, it does not come back when the amp is turned on another time.

 

Keep me in the loop, and you may feel free to call me at work for more detailed help over at GT.

 

Myles

[myles_rose]

Originally posted by Christopher Kemp:

Hi Myles -

 

trivia question - ever see/hear of a single EL34 amplifier? Is there some reason this would not be possible?

 

Sorry I missed you guys at the lunch with Lee last Saturday - hope you might make it to our dinner on Tuesday?

 

Cheers!

Christopher

Christopher ....

 

There are a few terrific single EL-34 amps at the moment:

 

THD Univalve (best amp in the world for under $5000.00)

 

James Peters

 

GT Solo Single

 

Take your pick ... all a bit different, all terrific.

 

Its too bad you missed the lunch. Aspen Pittman sent some "party favors" with me that were passed out, the food was great, the company was a blast and we all made new friends. Lee and Kyle were great at the show, and I was very impressed with Paul (the song writer).

 

Tuesday I am booked .... Thursday I have another concert somewhere in Santa Monica (I don't even know where I am supposed to be yet), but hopefully we will catch up.

 

Myles

[kirschke]

Hello Myles,

I learned by Your replies,that You are a great friend of KT 66, me too.Had You ever problems with

a PT,because the KT66 has a higher heater current

than the 6L6.

I have a NEW SENSOR 022798 PT in my amp-ALLEN OLD

FLAME,which I built myself,-which can handle 4A/6,3V.I have 2 12AX7 and 2 12AT7 which I think

have together 1,2A.Is this safe enough?

The last thing I would like to have is a blown PT at a gig.

How did Marshall handle this with the early Blues-

breaker combo?

Thanks,

Wolfgang

[myles_rose]

Originally posted by kirschke:

Hello Myles,

I learned by Your replies,that You are a great friend of KT 66, me too.Had You ever problems with

a PT,because the KT66 has a higher heater current

than the 6L6.

I have a NEW SENSOR 022798 PT in my amp-ALLEN OLD

FLAME,which I built myself,-which can handle 4A/6,3V.I have 2 12AX7 and 2 12AT7 which I think

have together 1,2A.Is this safe enough?

The last thing I would like to have is a blown PT at a gig.

How did Marshall handle this with the early Blues-

breaker combo?

Thanks,

Wolfgang

Wolfgang,

 

You actually have more than enough reserve. In the Bluebreaker it was also not an issue.

 

The heater current of a 6L6 is 0.9mA

 

KT-66's are 1.27mA

 

EL-34's are 1.5mA

 

But you are still just fine with any of those as your transformer is rated at less than a 100% duty cycle.

 

No Problem ...

 

Have fun .... KT-66's are great.

 

Myles

[alevinthal]

Originally posted by myles111:

Originally posted by aleinthal:

Hi Myles, I have a Randall RT-30, an amp that I love, with a wonderful and unique sound, but it needs an hour to warm up, sounds great for about an hour, and then 'loses the magic' over the next hour.

 

What makes an amp do this, and what can I do to get it to 'warm-up' faster, and then stay in that great tonal zone? I have 2 old boogies (studio 22 and MKII) that act the same way.

 

I have the schematics (as .pdf files) if you are interested in seeing them.

 

-Adam-

Adam,

 

If you have three tube amps that act the same way in your place, the first thing I would do is check your AC or borrow a variac and try one of the amps on there for a bit.

 

Myles

Hi Myles,

 

I guess I misspoke, the MKII is reasonably stable. The Studio 22 definitely drifts. The RT30 is my biggest concern though, since I prefer it to the Mesa's. The mains are probably not the issue since I play out a lot and it happens everywhere.

 

How stable should I expect the tone of a tube amp to be? What might I consider doing to make it more stable? How stable are the tranconductance curves of power tubes, in general? Are they sensitive to changes in temperature, or plate voltage? Might amps running class A be less stable than amps running class AB, since everything gets hotter? This amp runs four el84's at 380V with minimal regulation. A single emitter resistor biases all four tubes.

 

-Adam-

 

P.S. Dan Torres said he wasn't too surprised at this behaviour, and that some/most tube amps will drift, but I hate to have to just accept this. I was going to try a fan at the next show (thursday).

[rsf1977]

Originally posted by myles111:

Originally posted by rsf1977:

Hey Myles, I was practicing yesterday and infrequently my amp (mesa Dual Rectifier 2 channel Solo Head) would all of a sudden lose almost all volume and as it went down the sound got really grainy, do you know what could cause this?

 

I recently had couple weeks before had my pickup changed could it be a bad connection or something, About a month ago I switched to the Groove Tube GE-6L6s do you think it could be a bad power tube? Let me know, thanks.

rsf1977...

 

It could be a few things. On your rectifier, switch to the solid state setting when this happens and see if there is a change.

 

It very well could be one of your power tubes, they are fragile in shipping and that is why GT has their warranty.

 

If you have the set that came out of the amp, try them, and if they don't do the same thing, then I'd suspect one of the tubes as a possibility if once the GE tube goes off its prime, it does not come back when the amp is turned on another time.

 

Keep me in the loop, and you may feel free to call me at work for more detailed help over at GT.

 

Myles

Hey Myles I'll try swapping the tubes and see what happens. I always use the solid state rectifier so I guess that's not it right? And what were you saying about the GE Tubes, "if once the GE tube goes off its prime, it does not come back when the amp is turned on another time" what exactly did you mean. I'll let you know what happens, thanks again

[myles_rose]

Originally posted by alevinthal:

Originally posted by myles111:

Originally posted by aleinthal:

Hi Myles, I have a Randall RT-30, an amp that I love, with a wonderful and unique sound, but it needs an hour to warm up, sounds great for about an hour, and then 'loses the magic' over the next hour.

 

What makes an amp do this, and what can I do to get it to 'warm-up' faster, and then stay in that great tonal zone? I have 2 old boogies (studio 22 and MKII) that act the same way.

 

I have the schematics (as .pdf files) if you are interested in seeing them.

 

-Adam-

Adam,

 

If you have three tube amps that act the same way in your place, the first thing I would do is check your AC or borrow a variac and try one of the amps on there for a bit.

 

Myles

Hi Myles,

 

I guess I misspoke, the MKII is reasonably stable. The Studio 22 definitely drifts. The RT30 is my biggest concern though, since I prefer it to the Mesa's. The mains are probably not the issue since I play out a lot and it happens everywhere.

 

How stable should I expect the tone of a tube amp to be? What might I consider doing to make it more stable? How stable are the tranconductance curves of power tubes, in general? Are they sensitive to changes in temperature, or plate voltage? Might amps running class A be less stable than amps running class AB, since everything gets hotter? This amp runs four el84's at 380V with minimal regulation. A single emitter resistor biases all four tubes.

 

-Adam-

 

P.S. Dan Torres said he wasn't too surprised at this behaviour, and that some/most tube amps will drift, but I hate to have to just accept this. I was going to try a fan at the next show (thursday).

alevinthal ...

 

Dan Torres is right on the money. Amps drift, and mostly because of AC variances. I always use a variac when I work on amps, as everytime something turns on or off, even if not on the same circuit, things go way off.

 

380 volts on EL-84's is also a bit high, so they will run hot also. Class A amps run a LOT hotter, and this heats up everything, not just the tubes. Remember, a class A amp with no signal, is running at 100%, flat out ... so use the standby switch when not playing. This is the reason that AC-30's used to actually catch fire in some cases.

 

You can also drop the heat by using a cooler range of output tubes with the Mesa amps, but the amp will distort more quickly.

 

Regards,

 

Myles

[myles_rose]

Originally posted by rsf1977:

Originally posted by myles111:

Originally posted by rsf1977:

Hey Myles, I was practicing yesterday and infrequently my amp (mesa Dual Rectifier 2 channel Solo Head) would all of a sudden lose almost all volume and as it went down the sound got really grainy, do you know what could cause this?

 

I recently had couple weeks before had my pickup changed could it be a bad connection or something, About a month ago I switched to the Groove Tube GE-6L6s do you think it could be a bad power tube? Let me know, thanks.

rsf1977...

 

It could be a few things. On your rectifier, switch to the solid state setting when this happens and see if there is a change.

 

It very well could be one of your power tubes, they are fragile in shipping and that is why GT has their warranty.

 

If you have the set that came out of the amp, try them, and if they don't do the same thing, then I'd suspect one of the tubes as a possibility if once the GE tube goes off its prime, it does not come back when the amp is turned on another time.

 

Keep me in the loop, and you may feel free to call me at work for more detailed help over at GT.

 

Myles

Hey Myles I'll try swapping the tubes and see what happens. I always use the solid state rectifier so I guess that's not it right? And what were you saying about the GE Tubes, "if once the GE tube goes off its prime, it does not come back when the amp is turned on another time" what exactly did you mean. I'll let you know what happens, thanks again

rsf1977 ....

 

If one tube of an output set does something different than the others, but after a bit of rest, comes back, the tube may be faulty.

 

Myles

[ehv]

Hi Myles, first post here.....

 

I am having a problem with my 94' Fender "Twin Amp" (not Twin Reverb) that I'm wondering if you can help with. When I turn my reverb level above about 4, I start getting a ringing/feedback/high-pitched tone. The higher I turn my reverb level, the louder the feedback gets (gets very loud at 10). If I turn the reverb level down to 4 or below, the feedback goes away. The feedback builds slowly in level, takes 10-20 seconds to build up. It does it whether I'm in channel 1 or 2. If the volume level is turned to 0, and the reverb level is turned up, it still feeds back.

 

Any idea what's causing this? If it's a potential tube problem, do you know which tube/tubes drive the reverb? I have schematics (though I don't know much about reading them) and my best guess is that V5 (12AT7) and /or V6 (12AX7) are the reverb tubes.

 

If it needs to be serviced, do you have any recomendations for an amp tech in the Denver/Boulder CO area?

 

From reading many of the above posts, I know it's been said many times, but it really is great of you to take your time to help so many people out here!

 

Thanks for any help you can give on this!

 

Eric V

[not coaster MODERATOR]

Myles, I'm sure you have an opinion on this:

 

http://www.harmony-central.com/Newp/2002/RM50.html