Feel free to ask Myles

[hechtdavid]

Hi Myles, I've got a Music Man 110-RD Fifty for smaller gigs and rehearsing. As you probably know, its got a solid state front end and 2 6L6's for power. This model has one 12AX7 for the drive (limiter) channel. I tried a few different 12ax7's in there and the sound didn't seem to change much, so I ended up putting the original Sylvania back in there. I've got some NOS Phillips 7581A's for power and there is no bias adjustment (no standby switch either). Anything special I should know about caring for this little gem? Since MM is no longer in the amp biz and parts are probably scarce, I want her to be as healthy as possible. I've only replaced tubes with Svet 6L6GC's and the 7581a's so far. Any words of wisdom?

 

Thanks again and again,

 

David

[Rai168]

Hi Myles - sorry about hte confusing last post but it was comprised of 3 emails I had written. Anyhow - long story short, I got the RFT's and I'm pretty excited to hear em. Heard a lot of great things from other VHT owners who use them. Anyhow my 1 question is this -

 

On the VHT's (after speaking w Mike) I learned that 2 pre amp tubes by the power tubes in the back (Most of the tone chain is in front) are actually the phase inverter section. There are 2 tubes that do the Inverting. How would the theory of matched tubes in the PI section relate to this? One is a 12ax7 and the other a 12aT7? Would both tubes, both triode's for each tube - have to match w/in themselves?

 

Thanks Myles and sorry for the earlier confusion.

 

Best wishes -

 

Rai

www.CalyxinRuin.com

[myles_rose]

Originally posted by papamaverick:

Hey Myles

 

I emailed you but you mentioned it would be easier to get ahold of you on one of the forums, so here goes.

 

Love your articles…really neat stuff. I recently upgraded to JJ tubes at your recommendation and am very pleased. Anyhow, I have a quick question for you, since you're one of the people I KNOW has a good ear for sound. My rig is built around a Les Paul with Seymour Duncan Alnico II Pro (bridge) and '59 (neck) pickups and a Mesa Boogie Maverick. Both the guitar and amp produce nice, warm, vintage-y tones. The Maverick is similar in design to the Vox AC30 in regards to tubes…I'm using 6x JJ ecc83s and 4x JJ el84s; the Maverick I have is a 4x10 combo with Jensen P10R alnico speakers. It also has two channels—one cleaner and one that pushes the gain. However, I do not have much opportunity to play my amp to its fullest potential—normally, I'll end up w/ the master about ¼ way up. I've done my best to find a workable setting between the master and gain; but because of volume limitations (I'm pushing it as it is) I have to have the gain up around 5-6 to get a good crunch.

 

Let me explain what I am looking for: I want to be able to use this one amp (as I cannot afford another one) and get some el84-sounding distortion as well as a nice clean sound. I am buying a hotplate this summer, so I will be able to get it up to levels right before the el84s begin breaking up, but I'm still stuck using the preamp distortion (which is good, but just not power amp sounding). I've included a few hundred dollars in my summer budget to buy some distortion/overdrive/boost pedals; what should I get in order to have a nice distortion sound that's as close as I can get to el84 breakup without going all the way? At this point, I'm looking primarily at the Menatone Top Boost in a Can, the Vox V810 Valve Tone, and the Vox V830 Distortion Booster.

 

I play Brit pop / alternative music (heavy influences are U2, Radiohead, Pink Floyd, Oasis, etc. along with some more American-sounding bands such as Third Eye Blind and Goo Goo Dolls along w/ all the classic stuff-Hendrix, Zeppelin, Beatles, etc). Any help would be GREATLY appreciated.

papamaverick,

 

Thanks for sending your email over here. That way more folks get the possible benefit.

 

Thanks for the compliment on my ear. I wish I could also have a better ability to play I guess I was always trying to find how and what was used to make this or that recording over the years, so over time I turned into something of what is usually a vast storehouse of useless information!

 

Your rig sounds great. The SD Alnico's are great pickups and in a LP, a great combination that has both output but also articulate and defined highs, which are lost too often these days.

 

As far as your amp, the world's biggest secret it seems, are Mesa Class A amps. Everybody talks the Single, Dual, and Triple rectifiers and forgets amps like yours and the Blue Angel. If you want the Class A Vox/Matcheless sort of sound, these are a lot less expensive, and in the case of an AC-30, a lot more reliable and a lot easier to work on!

 

The ECC-83's are just the ticket for the Brit sound. The have a different plate structure than a 12AX7, especially different from the long plate Sovteks such as the LP and LPS. The short plate structure of the ECC83 also makes them less prone to microphonics, which really helps in some combo amps.

 

4x10's are the best option in that amp. The speaker cones are lighter than 12's, so there is faster transient response on the mid highs and highs. 4 10's also have more bass than 2 12"'s. My only complaint about a 4x10 combo is the weight!

 

Try the master ALL the way up sometime, as then it is effectively out of the circuit, and then drop your gain and use clean channel. Its pure blues, and makes a lot of AC-30's sound thin if their output transformers are getting old.

 

The THD hotplate is a great idea. It allows you to get the level of distortion you want, and with your amp, the more output tube distortion and less preamp tube distortion you can get, the better it sounds. Remember, the Vox AC-30 did not have all that much front end gain... its sound came from the output tubes being driven, not the front end. As far as the top boost variant, Brian May from Queen did not use a top boost, even he preferred the AC-30/4 rather than the TB AC-30/6.

 

With the hotplate, you can get the distortion you want and then set it to the overall level that you or others can stand.

 

As far as getting the output to break and distort at a more rational level (I know the Maverick is not supposed to be a 80+ watt amp, but 30 watts of Class A can be as loud as about 85 watts of class A/B ... just put a Matchless DC-30 next to a Fender Twin Reverb and compare) .... all you have to do is drop down to a lower output EL-84. You can go to Eurotubes and ask Bob Pletka for a softer set, something in a Groove Tubes #2 or #3 rating, or get Groove Tubes EL-34S (make sure they are the "S" tubes, as the other two they sell are Sovteks) in a #2 or #3 rating.

 

If I was in your area, I'd help you find a output set that ran about 38-40mA @ 250 volts with a -7.3 volt bias. The "normal" average tube at this setting would be about 48mA.

 

When you start to plug in pedals and effects, try to do so in the effects loop. If you plug into the amp input and you seem to see your high end and sparkle drop off, then replace V1 with a 7025. This is also an old Marshall trick. Remember though, it was the output distortion that makes these amps sound super, less of the preamp distortion.

 

I think with some of the above, you will be pretty happy. If some notes seem to have more sustain than others, go get a matched driver/phase inverter from Eurotubes or Watford Valves. They make a bigger difference than even in class A/B amps, and in A/B amps it can be pretty dramatic.

 

Hope this was of some value.

 

Regards,

[myles_rose]

Originally posted by paranoid:

What can you sey me about the new Laney 3 channels tt heads?

Thanks

paranoid,

 

I am sorry, but I know absoulutely nothing about them. I have not seen one myself. I don't have any clients using them currently.

 

Maybe check over on Harmony Central in the amp reviews section. Usually there is something there on just about any amp.

 

Regards,

[myles_rose]

Originally posted by Mr. Dan Licks:

Myles, you are a peach! What a man! Thanks again...and again...and again....

Dan

Dan,

 

You're welcome

 

Myles

[myles_rose]

Originally posted by deke1000:

Thanks so much Myles! I am giving your suggestions to my tech this weekend... hopefully it will be a cheap easy fix and I'll be back in business. Meanwhile, I'll be borrowing a buddy's Twin while the amp is in the shop -- we'll see how we gel. Thanks again for the tips!

deke1000,

 

You are welcome.

 

Feel free to have your tech drop me a line. I have an amp clinic this weekend, but can be reached at that store ( 818-789-8884 ) at California Vintage Guitar and Amp. I will be there from 11am to 4pm California time. He can also email me if he or she would like that better.

 

I'll be happy to try to help point them in the right direction so it will take less time, and hopefully cost you less money. If you were a pro, backed by Warner Reprise or somebody, then I'd let your record company suffer but for "real players" on a budget, I try to support them a bit more.

 

Regards,

[Griffinator]

OK, Myles - I'll throw one at you.

 

I'm looking at replacing the speakers and power tubes (4x6L6) in my Peavey Deuce VT. Someone suggested Celestion Vintage 30's, which I'm leaning towards, for speaker replacements. If you have a different opinion, I'm all ears. More importantly, though, what brand and spec 6L6 should I use?

 

Thanks in advance!

[myles_rose]

Originally posted by Rai168:

Hi Myles - sorry about hte confusing last post but it was comprised of 3 emails I had written. Anyhow - long story short, I got the RFT's and I'm pretty excited to hear em. Heard a lot of great things from other VHT owners who use them. Anyhow my 1 question is this -

 

On the VHT's (after speaking w Mike) I learned that 2 pre amp tubes by the power tubes in the back (Most of the tone chain is in front) are actually the phase inverter section. There are 2 tubes that do the Inverting. How would the theory of matched tubes in the PI section relate to this? One is a 12ax7 and the other a 12aT7? Would both tubes, both triode's for each tube - have to match w/in themselves?

 

Thanks Myles and sorry for the earlier confusion.

 

Best wishes -

 

Rai

www.CalyxinRuin.com

Rai168...

 

Each of the tubes in the phase inverter section should be matched. In stereo amp applications, there are also often 2 phase inverters/drivers.

 

Say hello to Mike from me if he is the Mike that used to be at Rivera.

 

Regards,

[myles_rose]

Originally posted by hechtdavid:

Hi Myles, I've got a Music Man 110-RD Fifty for smaller gigs and rehearsing. As you probably know, its got a solid state front end and 2 6L6's for power. This model has one 12AX7 for the drive (limiter) channel. I tried a few different 12ax7's in there and the sound didn't seem to change much, so I ended up putting the original Sylvania back in there. I've got some NOS Phillips 7581A's for power and there is no bias adjustment (no standby switch either). Anything special I should know about caring for this little gem? Since MM is no longer in the amp biz and parts are probably scarce, I want her to be as healthy as possible. I've only replaced tubes with Svet 6L6GC's and the 7581a's so far. Any words of wisdom?

 

Thanks again and again,

 

David

David,

 

These amps are pretty sturdy, so you probably don't have to worry all that much.

 

The reason you do not hear all that much of a difference when you change the preamp tube, is that a lot of the signal processing is done with a solid state front end, as is a lot of the gain and tone shaping. The tube is there mostly for compression.

 

On the output section, stick to good 6L6's. Svetlana's are a good bet in this amp and NO Chinese tubes should ever be used. These amps have some extremely high B+ voltages. I have seen some Music Man amps with 700 volts on the plates, and that is very very very high. The next highest I have seen is a 600 volt Marshall model 1959, which had a lot of power, but Marshall's seem to sound better at about 450 volts of B+ to most folks.

 

Make sure your amp is biased, and even though fixed bias, this can be checked, and if off, adjusted in other ways. If you stick to mid-range tubes, such as a Groove Tubes value of H5, you will be fine. This amp also likes all the tubes in the Mesa range, any of their color codes. Just only use their STR-454 (Svetlanas).

 

Keep the pots clean by using the amp a lot. Use the amp at least a few hours a month, and that will keep the caps in good shape.

 

Parts for these amps are not really hard to get, and are not all that expensive. Its harder to find some vintage amp parts for some of the more obscure amps, or tubes for some of the Ampeg's as as example.

 

These are great sounding amps, and unfortunately at times, VERY loud. You can get more output section distortion at lower volumes, and cool off the amp due to decreased current draw by using a Groove Tubes rating of #3 or #4, or a Mesa supplied tubes that are color coded RED or YELLOW. The REDs are cooler than Mesa's YELLOWs. These are both the same as a Groove Tubes #4 rating.

 

Stay clear of the 7581's in this amp as they have a 450 volt max grid #2 rating, while the 6L6GC has a rating of 500 volts. With the B+ your amp develops, that 50 volt margin is nice to have, as there is a lot of voltage on your plates and grid in its pentode configuration.

 

Your amp was one of only about three models they made with a tube in the preamp. The rest were all solid state. Your amp is considered the best sounding along with the "sixty-five" and the "one-thirty", and both of them used 6CA7 output tubes, a heavy duty USA version of an EL-34 that can handle 800 volts on the plates but still 500 volts on the grid.

 

Most of the amps I have measured like yours have about 585 volts of B+, but like I said, some have read much higher.

 

Your diode bridge is made up from 1N4003's rather than 1N4007's and they seem to last forever.

 

The only spot in the amp that might be considered a weak link in the chain, are transistors Q3 and Q4 that drive some of the output circuit. These are JE1692 parts, quite easy to find, not expensive, and that is about the only part I have seen fail. It failed when coffee went into the amp, so I guess I cannot call it a "weak link".

 

For some reason, even though they are somewhat complicated amps inside, with a lot of parts, they ship really well, and hold up on tours and bad handling. I don't know why exactly, but they are used by a lot of folks as backup amps when the more trendy boutique amps with all their point to point wiring fail or start making noise as the carefully laid point to point wiring moves around if not strain relieved properly. By the way, Carr amps, use proper strain relieving and are not subject to that last comment.

 

So, all in all, I guess all I can say, is stick some Svetlana's in there, and play your heart out, and if you feel free to do so, get some casters on your amp and ride it down the stage loading ramp. It does not seem to hurt them.

 

Its also nice, that they are not "vintage" or "boutique" amps with a high value, as they can still be found at good prices, and folks steal other amps first at a gig.

 

When somebody has something to say against solid state amps, these amps with a mostly, or totally solid state front end, can open a few eyes. They also show how important output tubes are in a hybrid design.

 

Happy playing

 

Regards,

[myles_rose]

Originally posted by Griffinator:

OK, Myles - I'll throw one at you.

 

I'm looking at replacing the speakers and power tubes (4x6L6) in my Peavey Deuce VT. Someone suggested Celestion Vintage 30's, which I'm leaning towards, for speaker replacements. If you have a different opinion, I'm all ears. More importantly, though, what brand and spec 6L6 should I use?

 

Thanks in advance!

Griffinator,

 

That's a hard one, as it is all personal taste. The Vintage 30's are great speakers. They have the same magnet structure at the "100" series, and can handle 60 watts with ease, so I was never sure why they called them "30"'s. They are also more efficient than a lot of other Celestions, at 100db at 1 meter with 1 watt.

 

I like Celetions for rock from the 80's and on, and Jensen P-12R's for rock from the 60's and 70's, or blues, but again, that is personal preference.

 

As far as output tubes, I'd go over to my website and look at the 6L6 reviews that were done by Watford Valves, and read their feelings, and stay clear of my technical mumbo jumbo for the most part.

 

When it comes down to personal taste, I have copied something I said once before in a forum response, when somebody asked me which of two amps was better. I think it applies here too, so here it is again:

 

This was in response to a forum question where somebody was asking which of two amps was "better"

 

Hmmmmm....

 

Bogner or Soldano? Which is better?

 

Can I ask a question to help answer the question ....

 

You are walking down the street on a nice day. You are a single male, open to a night out with female company if the situation presents itself. As you walk down the street, coming right toward you are two girls.

 

One is 5'8", blonde hair, green eyes, and drop dead gorgeous.

 

The other is 5'4" brunette, blue eyes, and equally as much of a knockout.

 

As they both approach and get close enough to speak, one of them gives you a big smile and starts the opening of conversation, and starts to flirt with you in a nice way.

 

Do you really care at this point which one of them it was?

 

Just like girls .... or guys (if you're female) ... or actually girls and girls or guys and guys or .... Its a matter of what you are open to at the time and what appeals to you. Both the girls in this case are terrific, and I think both your amp examples are terrific too... its a matter of taste and timing .... how much cash do you have in your pocket when you walk into the store and one of those amps is on the floor.

 

Regards and sorry if this was no help at all

[Griffinator]

Well, there's two things I wanted to accomplish by asking these questions.

 

1) Get a clearer picture of what to absolutely avoid in brands.

 

2) Gain a better understanding of how a given spec tube will affect the sound of the amp - especially in the power stage.

 

I like the sound of this amp through a couple of cabs I've plugged it into - one was a Carvin 4x12, the other a late 60's Ampeg bass cab loaded with Celestion Greenbacks. Obviously, with the power tubes shot to heck, the longer it was on, the less I liked it.

 

I really want to recapture the vintage Deuce sound, but I've little faith in Black Widow speakers or SovTek tubes...

[myles_rose]

Originally posted by Griffinator:

Well, there's two things I wanted to accomplish by asking these questions.

 

1) Get a clearer picture of what to absolutely avoid in brands.

 

2) Gain a better understanding of how a given spec tube will affect the sound of the amp - especially in the power stage.

 

I like the sound of this amp through a couple of cabs I've plugged it into - one was a Carvin 4x12, the other a late 60's Ampeg bass cab loaded with Celestion Greenbacks. Obviously, with the power tubes shot to heck, the longer it was on, the less I liked it.

 

I really want to recapture the vintage Deuce sound, but I've little faith in Black Widow speakers or SovTek tubes...

Griffinator,

 

In your amp, my personal choice would be Svetlana 6L6's for more rock, or NOS 5881's for a bit less power but more articulation and definition.

 

With 5881's I'd also use a JAN 5751 tube in your first gain stage.

 

For speakers, I'd use Weber's or my standby Jensen's with Alnico magnets.

 

Regards,

[Griffinator]

Thanks - I'll experiment a bit with some of those combinations, and let you know how it goes

[Rai168]

Thank you very much Myles for your patience and answer. I will pass on the hello - take care and again Thank you.

 

Rai

www.CalyxinRuin.com

 

Originally posted by myles111:

Originally posted by Rai168:

Hi Myles - sorry about hte confusing last post but it was comprised of 3 emails I had written. Anyhow - long story short, I got the RFT's and I'm pretty excited to hear em. Heard a lot of great things from other VHT owners who use them. Anyhow my 1 question is this -

 

On the VHT's (after speaking w Mike) I learned that 2 pre amp tubes by the power tubes in the back (Most of the tone chain is in front) are actually the phase inverter section. There are 2 tubes that do the Inverting. How would the theory of matched tubes in the PI section relate to this? One is a 12ax7 and the other a 12aT7? Would both tubes, both triode's for each tube - have to match w/in themselves?

 

Thanks Myles and sorry for the earlier confusion.

 

Best wishes -

 

Rai

www.CalyxinRuin.com

Rai168...

 

Each of the tubes in the phase inverter section should be matched. In stereo amp applications, there are also often 2 phase inverters/drivers.

 

Say hello to Mike from me if he is the Mike that used to be at Rivera.

 

Regards,

[jivey311]

What's the difference between 6L6's and EL34's? In my JCM900 50 watt head, I have 6L6's, can I change those to EL34's? The 30 watt ones?

[HBK]

Hi Myles,

 

I'm thinking about buying the Marshall AVT20 amp. I play mostly rock/hard rock and punk (Oasis - Nirvana). The amp will be for bedroom use mainly, I'm concerned the amp won't give me the distortion/tone I need at low volumes. Have you heard this amp in action at these kind of volumes ? I've been phoning local music shops to try it out but none seem to have them in stock at the moment. Any help would be great,

 

Thanks.

[myles_rose]

Originally posted by jivey311:

What's the difference between 6L6's and EL34's? In my JCM900 50 watt head, I have 6L6's, can I change those to EL34's? The 30 watt ones?

jivey311,

 

They are very different tubes. I have made a number of posts in this forum on that subject. There is also a lot of info on that on my website.

 

Basically, you should not have 6L6's in a stock Marshall JCM 900, as its output transformer was set for the impedience of EL-34's, which is a bit different than 6L6's. This won't hurt anything, and a lot of folks do this sort of thing.

 

In any case, you can use any of the EL-34's in your amp, just make sure to have the bias checked. These are the original tubes in your Marshall and will make it sound like what folks think Marshalls generally sound like.

 

I hope when the 6L6's we installed, the bias was changed. If not, your amp is not sounding anywhere as nice as it could, even with the 6L6's.

 

Your preamp tubes in that amp, for the typical Marshall sound and the way it came from the factory, should be ECC83's by the way.

 

Regards,

[myles_rose]

Originally posted by HBK:

Hi Myles,

 

I'm thinking about buying the Marshall AVT20 amp. I play mostly rock/hard rock and punk (Oasis - Nirvana). The amp will be for bedroom use mainly, I'm concerned the amp won't give me the distortion/tone I need at low volumes. Have you heard this amp in action at these kind of volumes ? I've been phoning local music shops to try it out but none seem to have them in stock at the moment. Any help would be great,

 

Thanks.

HBK,

 

The folks you mention and the style of music they play and you like, uses a lot more front end distortion than output section distortion. That means you are in luck in a few ways.

 

Just about any of the AVT series can have the volume/gain cranked a bit on the high side, then the master set low, and still get a lot of drive and distortion at lower levels.

 

I'd go to the Harmony Cental forums, look in the amp reviews by their users, and it will probably tell you all you might need to know and more.

 

Regards,

[GTO]

Myles, great info! I hope you're still around.

Could you go over the basics of using the "Standby" switch, or point us to a link. I believe this is a much overlooked issue with tube amps and improper use can cause tubes to wear out prematurely. Also, I'm sure that I'll learn something too, as I'm certainly no expert.

 

Thanks.

[not coaster MODERATOR]

Myles- I think you memtioned that you know the gent who puts together the JT Pedals for Mesa Boogie. I own the Valveboy and Can't begin to describe what an upgrade it is from the Visual Sound J&H, which I had thought was a pretty decent Plexi Tone. Have you gotten a chance to try it out?

 

I've not talked to anyone else with one either. Just wanted to say it's in a league of its own and see what you thunk.

 

Cereal

[JamesPeters]

Hey GTO, mind if I butt in?

 

The standby switch is used to break the connection of the high voltage in the amp. That would leave only the filament heater supply of the tubes powered when the power is on (and the standby is off). The whole deal with that is to let the tubes heat enough to be able to handle their operation. It takes between 30-90 seconds (depending on the tube) to fully heat the tube's filaments to a normal operating temperature.

 

If the tubes filaments aren't hot enough, what can happen is that if signal hits the grid of the tube it starts going about doing its thing...and electrons get stripped off the cathode ("cathode stripping"), resulting in premature tube wear. Keeping standby off for the first couple minutes the amp is on, then turning standby on, will help keep your tubes healthy longer. If your amp doesn't have a standby, then it's advisable to not play your guitar until the amp has been on a couple minutes. If the amp has a tube rectifier, those take a while to get the high voltage up to proper range, so in reality standby may not be needed on any amp with a tube rectifier. I'd still use the standby though if it's on the amp, since you're not "rushing" to start playing before the tubes are good and ready.

 

Powering down, it might probably be just as good to shut the standby off first until signal is gone...although I'm not sure if this matters or not since if you powered down while signal is on, it takes the tubes' filaments a while to cool.

 

The issue of shutting off with/without standby gets thrown around a lot, but nothing significant has come of the discussions as far as I know. One guy I know said he puts it on standby for a few minutes before shutting off, to let the tubes cool...but the logic in this seems flawed--if the tubes get that much hotter from the high voltage being on the plates, then how significant a difference is it if you remove the plate voltage first, then remove the filament supply later. I mean, do your tubes really cool more evenly by doing this? It seems unlikely.

 

Oh well. That's all I got!

[Gabriel E.]

Myles,

 

Ok. Here's a question that's been bugging me:

 

I have a Fender 5F4 Super Amp that someone cut into a head. It puts out about 28 watts into 4 ohms. I have 2 - 8ohm speaker cabs that I run it through (an open back with Celestion Vintage 30s and a closed back with Celestion G12M75s). While both cabs together sound good, I like the more compressed sound and lower volume of the amp running into a single 8 ohm cab.

 

So: Can I run the amp into an ABY box and switch between the two cabs while the amp is running (the open back for clean, the closed back for dirty)? Can I switch between one cab on to BOTH cabs on while the amp is running?

 

Thanks,

 

Gabriel

[papamaverick]

Hey Myles

 

Your last answer helped a lot. I'm pretty sure I know what I need to do now.

 

One last question...for my Mesa Maverick, would buying a NOS 5ar4/GZ34 rectifier tube (I'd probably go for the Mullar) make any difference in comparison to the stock tube (Chinese)?

 

Dave

[myles_rose]

Originally posted by GTO:

Myles, great info! I hope you're still around.

Could you go over the basics of using the "Standby" switch, or point us to a link. I believe this is a much overlooked issue with tube amps and improper use can cause tubes to wear out prematurely. Also, I'm sure that I'll learn something too, as I'm certainly no expert.

 

Thanks.

GTO ...

 

I am still around ....

 

The standby switch generally has a fairly simple purpose.

 

There are a number of voltages in an amplifier.

 

There is the "heater" voltages, generally either 6.3 volts or 12.6 volts. When the amp is on and the standby ON or OFF, this voltage is still applied to the tubes. It is the glow you see in all the tubes, and the preamp tubes.

 

The preamp tubes also have plate voltages, and these are also on as soon as the amp power switch is on.

 

In the case of the power tubes, with the standby switch OFF, there is heater voltage (so the tubes light up), but the PLATE voltage, also called B+ voltage is off. These are high voltages, from 300 volts to over 600 volts in some amps.

 

When you first turn on your amp, wait about 30 seconds at the least, to give the tubes time to come up to operating temperature, before you flip the standby switch to operating position. This will help get the most tube life from your output set. I also like to leave the amp in standby mode for about five minutes after playing hard, to let the tubes cool down more slowly in most amps.

 

Hope this helped.

 

If you want to more in depth about tubes, on my website is a sort of reddish box with a link in there.

 

Regards,

[myles_rose]

Originally posted by Cereal:

Myles- I think you memtioned that you know the gent who puts together the JT Pedals for Mesa Boogie. I own the Valveboy and Can't begin to describe what an upgrade it is from the Visual Sound J&H, which I had thought was a pretty decent Plexi Tone. Have you gotten a chance to try it out?

 

I've not talked to anyone else with one either. Just wanted to say it's in a league of its own and see what you thunk.

 

Cereal

Cereal,

 

Those pedals were done by John. I have played with them a bit, and I have to agree, they are great.

 

What you have to think about though, is that they were designed by a guy that has been a crack amp tech for Mesa for years (and also a great amp guy on other amps too), and he's also a great player that performs. This is a little different from somebody like me, and actually a lot of the other techs I know ... most of us are "okay" or "fair" players, and don't perform all that much, if it all.

 

In the case of a lot of techs and engineers, we think we "know" what folks want. I think that is why whenever I do amp work, folks just cannot drop of the amp and come back a week later. I need them to be there when the amp work is being done. That way its not a case of me thinking I know what they want, but them telling me yes or no as work progresses.

 

In the case of John at Mesa, he knows what he wants, and he knows how it will be used in a real performance situation. Andy Marshall from THD is another of those fellows that is also a "player", and that's why so many of his designs work out so well. Being tech types, these folks also know how and why things fail, so there is also a reliability component in their designs that is not there at times when some "engineer" makes a design from a parts catalogue.

 

I'm sure you'll be happy for a lot of years, and your grandkids will probably end up with some sort of classic vintage piece of gear

 

Regards,

[myles_rose]

Originally posted by JamesPeters:

Hey GTO, mind if I butt in?

 

The standby switch is used to break the connection of the high voltage in the amp. That would leave only the filament heater supply of the tubes powered when the power is on (and the standby is off). The whole deal with that is to let the tubes heat enough to be able to handle their operation. It takes between 30-90 seconds (depending on the tube) to fully heat the tube's filaments to a normal operating temperature.

 

If the tubes filaments aren't hot enough, what can happen is that if signal hits the grid of the tube it starts going about doing its thing...and electrons get stripped off the cathode ("cathode stripping"), resulting in premature tube wear. Keeping standby off for the first couple minutes the amp is on, then turning standby on, will help keep your tubes healthy longer. If your amp doesn't have a standby, then it's advisable to not play your guitar until the amp has been on a couple minutes. If the amp has a tube rectifier, those take a while to get the high voltage up to proper range, so in reality standby may not be needed on any amp with a tube rectifier. I'd still use the standby though if it's on the amp, since you're not "rushing" to start playing before the tubes are good and ready.

 

Powering down, it might probably be just as good to shut the standby off first until signal is gone...although I'm not sure if this matters or not since if you powered down while signal is on, it takes the tubes' filaments a while to cool.

 

The issue of shutting off with/without standby gets thrown around a lot, but nothing significant has come of the discussions as far as I know. One guy I know said he puts it on standby for a few minutes before shutting off, to let the tubes cool...but the logic in this seems flawed--if the tubes get that much hotter from the high voltage being on the plates, then how significant a difference is it if you remove the plate voltage first, then remove the filament supply later. I mean, do your tubes really cool more evenly by doing this? It seems unlikely.

 

Oh well. That's all I got!

James....

 

I saw the post on this question, and replied to it before I saw your answer to his question. If I would have saw your answer first, I would have just pointed to your answer!

 

The last paragraph of your answer is confusing to me a little, I think its the nomenclature of standby ON vs OFF at times.

 

I think moving the standby swith to the position where the amp will NOT play, meaning the B+ is turned off, is what I like to do for a few minutes before shutting down an amp, especially a Class A amp, that with the B+ on, runs just as hot as it would when run full bore. The tubes would have a lower bulb temerature after a few minutes with the heater on and the B+ off, than with the heater on and the B+ on. I think this is what you were also saying, but the ON and OFF, vs STANDBY and OPERATE, or something like that, sometimes can get confusing.

 

By the way, how is your latest amp coming along?

 

An interesting side issue on your amp on this subject in a way ... on a single ended class A chatode biased amp, there is a fun little phenomonon (I probably trashed the spelling on that word), that happens in these amps. At idle, they draw max current, but at full load, they actually develop a tiny bit less current draw, in the 1/10ths of percentage points mostly, but still a micro bit less. Nothing really worth ever considering, but interesting for some like me that don't have better things to think about at times

 

Regards,

[myles_rose]

Originally posted by Gabriel E.:

Myles,

 

Ok. Here's a question that's been bugging me:

 

I have a Fender 5F4 Super Amp that someone cut into a head. It puts out about 28 watts into 4 ohms. I have 2 - 8ohm speaker cabs that I run it through (an open back with Celestion Vintage 30s and a closed back with Celestion G12M75s). While both cabs together sound good, I like the more compressed sound and lower volume of the amp running into a single 8 ohm cab.

 

So: Can I run the amp into an ABY box and switch between the two cabs while the amp is running (the open back for clean, the closed back for dirty)? Can I switch between one cab on to BOTH cabs on while the amp is running?

 

Thanks,

 

Gabriel

Gabriel,

 

The 5F4 Super used two speakers as stock.

 

As long as your impedience does not drop below four ohms, you will be okay.

 

With two eight ohm cabinets in parallel, you would still be safe.

 

You need a good switch though, that with switch in a clean way without any spikes. Something like what stereo stores use when the demo speakers, switching from one to another using the same amp.

 

It sounds like with your 2 eight ohm cabinets, that the the 2x12's is probably two 16 ohm speakers wired in parallel, so this is fine.

 

The mix of the V30's and 75's is a nice combination. The speakers are very close in efficiency, within 2db or so, but have different resonant frequecies. This really opens up a sound image. Folks today are getting wise to this by putting two different speakers in the same combo amp or cabinet. For years I have used 1x12 ported cabinets with different Celections in each. It makes more of a stereo sort of image, than a bigger mono sort of image.

 

The Super's even at 28 watts, are loud amps. I can see where using two cabinets could be too loud at times. When you double your speaker radiating area, you just about quadruple your sound levels.

 

Just have a good switch, and this will work very nicely. Running one cab at 8 ohms will drop your power a bit, but remember, when a speaker is marked as being 8 ohms, that is 8 ohms nominal ... i.e., its lowest value at a given frequency. At other frequencies, it can be 75 ohms, 92 ohms, 18 ohms, or whatever. Its the lowest value we are concerned about, and in your case, you are safe.

 

Regards,

[myles_rose]

Originally posted by papamaverick:

Hey Myles

 

Your last answer helped a lot. I'm pretty sure I know what I need to do now.

 

One last question...for my Mesa Maverick, would buying a NOS 5ar4/GZ34 rectifier tube (I'd probably go for the Mullar) make any difference in comparison to the stock tube (Chinese)?

 

Dave

Dave,

 

The Mullard will be much more reliable, but then again, the Chinese ones, when they fail, usually fail in the first hours of use, so you are pretty safe at this point.

 

The Mullard will give you more B+ voltage, but Mesa amps seem to sound prettier to me at least, as their voltages are not extreme, and they are closer to the sweet spot that tubes prefer. If you want more B+ voltage and a tighter and brighter sound, just flip the switch to your solid state rectifier. Sort of the best of both worlds.

 

These amps are really terrific. For now, I'd just spend time playing and enjoying the amp. If you have more than a few hours on your stock GZ34, it should be fine, and I'd pass on the extra money. I have the stock rectifier in a Blue Angel, and its been just fine and dandy for years. If I plug in a NOS rectifier in the Blue Angel, I personally notice no difference in that particular amp or circuit, but have measured about a 25 volt change in B+. So at least in my amp, 25 volts does not make a change to my ears or to a few others I have shown this to also.

 

It does make a difference in some older amps, like tweed Fenders, whose power transformers are getting weak, and saggy, and having a good strong rectifier is pretty important if you want more of the original sound from these amps. The again, lot of folks like the "aged" sound some of these amps produce.

 

In the case of your amp, Mesa amps in general, have very nice power sections, and your amp will develop its intended voltages in the power supply section long enough that when your grandkids play their old grand dad's "vintage" amp from the 20th century, it will still be working great.

 

I tend to get wordy .... always .... so bottom line ..... You have a great amp. Save your money and take the $75 or maybe even more for a Mullard GZ-34, and go out to dinner with your wife or girlfriend or significant other, or even somebody you pick up somewhere if you are still young enough or good looking enough to do that sort of thing

 

Regards;

[Gabriel E.]

You need a good switch though, that with switch in a clean way without any spikes. Something like what stereo stores use when the demo speakers, switching from one to another using the same amp.

Thanks for the quick reply Myles. Just to be safe - the jump from 4 ohms to 8 ohms doesn't qualify as a spike?

 

I have a Morley ABY switch. Probably not quiet enough huh?

 

Thanks again,

 

Gabriel

[GTO]

Originally posted by JamesPeters:

Hey GTO, mind if I butt in?

 

The standby switch is used to break the connection of the high voltage in the amp. That would leave only the filament heater supply of the tubes powered when the power is on (and the standby is off). The whole deal with that is to let the tubes heat enough to be able to handle their operation. It takes between 30-90 seconds (depending on the tube) to fully heat the tube's filaments to a normal operating temperature.

 

If the tubes filaments aren't hot enough, what can happen is that if signal hits the grid of the tube it starts going about doing its thing...and electrons get stripped off the cathode ("cathode stripping"), resulting in premature tube wear. Keeping standby off for the first couple minutes the amp is on, then turning standby on, will help keep your tubes healthy longer. If your amp doesn't have a standby, then it's advisable to not play your guitar until the amp has been on a couple minutes. If the amp has a tube rectifier, those take a while to get the high voltage up to proper range, so in reality standby may not be needed on any amp with a tube rectifier. I'd still use the standby though if it's on the amp, since you're not "rushing" to start playing before the tubes are good and ready.

 

Powering down, it might probably be just as good to shut the standby off first until signal is gone...although I'm not sure if this matters or not since if you powered down while signal is on, it takes the tubes' filaments a while to cool.

 

The issue of shutting off with/without standby gets thrown around a lot, but nothing significant has come of the discussions as far as I know. One guy I know said he puts it on standby for a few minutes before shutting off, to let the tubes cool...but the logic in this seems flawed--if the tubes get that much hotter from the high voltage being on the plates, then how significant a difference is it if you remove the plate voltage first, then remove the filament supply later. I mean, do your tubes really cool more evenly by doing this? It seems unlikely.

 

Oh well. That's all I got!

James,

Please butt in any time. Great info, you cleared up the issue that I was most concerned about, when to switch to standby at power-on.

 

Thanks!