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Originally posted by PBBPaul:

Myles,

 

I am considering using 3 10-inch speakers with my '65 Bandmaster. The amp is rated for a 4-ohm load. I've read that these older Fenders are designed to handle a 50% impedance load variation in either direction. Is this true? The Speaker and Extension Speaker jacks are wired in parallel which leads me to believe this but I thought I'd check with you first. If I use 3 8-ohm speakers in parallel, I'd get a total load of 2.67 ohms. I realize that this will tax the power tubes but is there any risk to the output transformer? What is your recommendation for a 3x10 speaker setup? 2 16-ohms and a 8-ohm will give me a total load of 4 but I'd like to keep the speakers matched if I can.

 

Thanks,

 

Paul

Paul,

 

The best way to do this would be to use a tweed bandmaster OT which was spec'd at 2.7 ohms. This will work best. If you don't want to do that, you are better going higher than lower, so personally, I'd use 3 16 ohm 10" speakers rather than 3 8 ohm ten inchers.

 

You could probably get a great transformer from Mark Baier at Victoria Amplifier, who could also give some great tips and advice.

 

Mercury Magnetics ( Sergio ) is also another great source.

Myles S. Rose

www.guitaramplifierblueprinting.com

www.la-economy.blogspot.com

www.facebook.com/mylesr

www.twitter.com/myles111us

 

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Thank you Myles.

 

I have one other question. I'd like to jumper the two channels of this Bandmaster like I do with my Bassman but the sound is really strangled when I do so. It sounds like the two channels are out of phase. Is that normal? Is there a mod to fix that? It would seem like it would be a fairly simple thing to do. I found this mod: http://community.webshots.com/photo/63936117/66383305LaywDw but I don't care if I have tremolo in both channels. I just want them in phase.

 

Thanks again,

 

Paul

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Myles,

 

I was just checking out the numbers on this old Bandmaster. My output transformer does not appear to be original. If I understand correctly, it should have a part number of 022..... but the part number is 0822848 and the EIA number is 606-641 which leads me to believe that it was made in 1966 when the amp bears a mfr date of January 1965 and all the other dates indicate 1964. So... How can I check this OT for load requirements and make sure that it is right. I haven't been able to find the part number referenced anywhere.

 

Thank you as always.

 

Paul

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Hi Myles.

 

I'm lost on this AC-30 thing.

 

Going by the photo below, can you tell me what the pre-amp tube configuration is? (V1, V2 etc.)

 

Thanks.

 

http://www.voxshowroom.com/northcoast/images/products/new_amplifiers/ac30service/chart.jpg

So Many Drummers. So Little Time...
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Originally posted by PBBPaul:

Thank you Myles.

 

I have one other question. I'd like to jumper the two channels of this Bandmaster like I do with my Bassman but the sound is really strangled when I do so. It sounds like the two channels are out of phase. Is that normal? Is there a mod to fix that? It would seem like it would be a fairly simple thing to do. I found this mod: http://community.webshots.com/photo/63936117/66383305LaywDw but I don't care if I have tremolo in both channels. I just want them in phase.

 

Thanks again,

 

Paul

Paul,

 

This should work.

Myles S. Rose

www.guitaramplifierblueprinting.com

www.la-economy.blogspot.com

www.facebook.com/mylesr

www.twitter.com/myles111us

 

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Originally posted by rsf1977:

Hey Myles, bob from eurotubes is sending me a set for that purpose. How do I check my amp bias anyway? Can you recommend a meter to do that with that I can use at home?

rsf1977 -

 

There are a lot of bias tools on the market, I personally used the GT one long before I came to work at GT, as I prefer the ones that do not have a built in meter ... less problems, less space in my toolbox, and less costly.

 

The GT one can be found at http://www.groovetubes.com/groovetoys.cfm?Category_ID=30 and ordered directly off the website or purchased from any GT dealer.

Myles S. Rose

www.guitaramplifierblueprinting.com

www.la-economy.blogspot.com

www.facebook.com/mylesr

www.twitter.com/myles111us

 

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Originally posted by PBBPaul:

Myles,

 

I was just checking out the numbers on this old Bandmaster. My output transformer does not appear to be original. If I understand correctly, it should have a part number of 022..... but the part number is 0822848 and the EIA number is 606-641 which leads me to believe that it was made in 1966 when the amp bears a mfr date of January 1965 and all the other dates indicate 1964. So... How can I check this OT for load requirements and make sure that it is right. I haven't been able to find the part number referenced anywhere.

 

Thank you as always.

 

Paul

Paul,

 

Many times dates on components are earlier than the amp, as it was older stock.

 

I would measure the windings to be sure of the transformer.

 

This is a bit complex to get into here, so you may want to check a transformer mfg website like Mercury Magnetics.

Myles S. Rose

www.guitaramplifierblueprinting.com

www.la-economy.blogspot.com

www.facebook.com/mylesr

www.twitter.com/myles111us

 

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Originally posted by KHAN:

Hi Myles.

 

I'm lost on this AC-30 thing.

 

Going by the photo below, can you tell me what the pre-amp tube configuration is? (V1, V2 etc.)

 

Thanks.

 

http://www.voxshowroom.com/northcoast/images/products/new_amplifiers/ac30service/chart.jpg

V1 is closest to the input jack, and the ECC82 is your phase inverter.

 

If you email me, I will send you a print. techsupport@groovetubes.com

Myles S. Rose

www.guitaramplifierblueprinting.com

www.la-economy.blogspot.com

www.facebook.com/mylesr

www.twitter.com/myles111us

 

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Hey, Steve F! I'll see if I can help...

 

For starters, I've "bumped" the thread Myles has posted on phase inverters to the top (for now).

 

Balanced matching of the two triodes that are inside the driver- , or phase inverter- tube, is more critical to good tone than the overall gain. (All of the common nine-pin miniatures, the 12A- types, currently popular in the vast majority of guitar amps are "dual triodes"; kinda like two tubes in one.)

 

The gain of the tube used in this position in your amp will affect the overall amount of headroom before breakup, as this will determine just "how hard" the driver pushes the output tubes. If you want a cleaner sound with more headroom, go with a 12AT7, 12AU7, etc. As long as the tube is a nine-pin mini dual triode, you won't hurt anything; but, as I mentioned, and you'll read more in Myles' thread, it helps immensely to use a high-quality "matched" specimen.

 

Best of luck! -k

Ask yourself- What Would Ren and Stimpy Do?

 

~ Caevan James-Michael Miller-O'Shite ~

_ ___ _ Leprechaun, Esquire _ ___ _

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Myles,

I have a Tube Works Smooth 303 pedal, which contains (so they say) a 12AX7 tube - I have no idea what kind. I have never been too thrilled with the tones (trebble is kind of brittle, bass is a little mushy, etc.). I just wanted to add a little tube warmth to my sound, and a touch of overdrive.

Do you know if it is even worth it to open this thing up, find out what tube is in there, and maybe replace it? Or should I just sell it on Ebay?

 

Thanks for any advice you might have!!

May all your thoughts be random!

- Neil

www.McFaddenArts.com

www.MikesGarageRocks.com

 

 

 

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Originally posted by KHAN:

Originally posted by myles111:

]V1 is closest to the input jack, and the ECC82 is your phase inverter.

 

If you email me, I will send you a print. techsupport@groovetubes.com

Thanks Myles.

 

A G A I N ! ! ! :thu::D

KHAN - you are more than welcome.

Myles S. Rose

www.guitaramplifierblueprinting.com

www.la-economy.blogspot.com

www.facebook.com/mylesr

www.twitter.com/myles111us

 

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Originally posted by CaevanO'Shite:

Hey, Steve F! I'll see if I can help...

 

For starters, I've "bumped" the thread Myles has posted on phase inverters to the top (for now).

 

Balanced matching of the two triodes that are inside the driver- , or phase inverter- tube, is more critical to good tone than the overall gain. (All of the common nine-pin miniatures, the 12A- types, currently popular in the vast majority of guitar amps are "dual triodes"; kinda like two tubes in one.)

 

The gain of the tube used in this position in your amp will affect the overall amount of headroom before breakup, as this will determine just "how hard" the driver pushes the output tubes. If you want a cleaner sound with more headroom, go with a 12AT7, 12AU7, etc. As long as the tube is a nine-pin mini dual triode, you won't hurt anything; but, as I mentioned, and you'll read more in Myles' thread, it helps immensely to use a high-quality "matched" specimen.

 

Best of luck! -k

CaevanO'Shite ......... great answer........

 

I will just add a touch ..... a 12AX7 is "supposed" to have a gain/Mu of 100. Most today are not near that by the way. The output is supposed to be 1.2 milliamps.

 

A 12AT7 has a gain/Mu of about 70 ... about 30% less, BUT has a current output of about 10 milliamps, or about 8x more current drive than a 12AX7. This yields better control of the output section, and at the same time, with less gain, the ratio of output tube distortion to preamp tube distortion is slanted more to the output tube side, which is a different sort of character (pentodes distort different than triodes).

Myles S. Rose

www.guitaramplifierblueprinting.com

www.la-economy.blogspot.com

www.facebook.com/mylesr

www.twitter.com/myles111us

 

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Originally posted by NMcGuitar:

Myles,

I have a Tube Works Smooth 303 pedal, which contains (so they say) a 12AX7 tube - I have no idea what kind. I have never been too thrilled with the tones (trebble is kind of brittle, bass is a little mushy, etc.). I just wanted to add a little tube warmth to my sound, and a touch of overdrive.

Do you know if it is even worth it to open this thing up, find out what tube is in there, and maybe replace it? Or should I just sell it on Ebay?

 

Thanks for any advice you might have!!

NMcGuitar ...........

 

Before you sell it and take a beating, stick a 12AX7C in there. They are less brittle and much more warm and linear.

 

If you are in the L.A. area, let me know, I will give you one for free that I would hand select for you. Sorry, but I don't have enough hours in the day to mail stuff, no matter what folks offer to pay.

 

You can also maybe find somebody in L.A. if you are not here, work some sort of deal with them, and I'd be more than happy to give them the tube to send to you ...........

 

OR ............ you can contact Ludovic Pierson at www.tubecellar.com who is in LA that I see all the time, work out a deal with him that if I give him the tube, you'd pay him to box and ship it maybe.

 

Any of the options is fine ...........

 

Or ......... contact Doug Preston as www.dougstubes.com and he might sell you one real cheap, just tell him that on his VTV tester, to find you a 12AX7C that reads BELOW 95. He has a lot of great stuff.

 

In any case, any of these sources should be between free and less than $10.00, so try that before selling it.

Myles S. Rose

www.guitaramplifierblueprinting.com

www.la-economy.blogspot.com

www.facebook.com/mylesr

www.twitter.com/myles111us

 

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Myles,

Thanks for all the great info on amps and tubes. This has got to be the most informative site on the web for this stuff.

I have a Fender Vibroking that has just picked up a loud oscillating buzz. I changed all the tubes and it's still there. The buzz sounds the same regardless of volume and the amp tone is fine except for this buzz. If I turn the volume to zero it's still there and makes a loud click when the volume is turned past zero.

They only thing out of the ordinary was that recently the cord was pulled out of the guitar by mistake when the amp's volume was on 3.

 

Let me know of any suggestions. The voltage on the power tubes is where it is supposed to be at 450 volts.

Thanks for your time.

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Originally posted by Mitch Harris:

Myles,

Thanks for all the great info on amps and tubes. This has got to be the most informative site on the web for this stuff.

I have a Fender Vibroking that has just picked up a loud oscillating buzz. I changed all the tubes and it's still there. The buzz sounds the same regardless of volume and the amp tone is fine except for this buzz. If I turn the volume to zero it's still there and makes a loud click when the volume is turned past zero.

They only thing out of the ordinary was that recently the cord was pulled out of the guitar by mistake when the amp's volume was on 3.

 

Let me know of any suggestions. The voltage on the power tubes is where it is supposed to be at 450 volts.

Thanks for your time.

Mitch -

 

This can be all sorts of things, and you and I may not have the same definition of "buzz".

 

It's time to get the amp to a tech.

Myles S. Rose

www.guitaramplifierblueprinting.com

www.la-economy.blogspot.com

www.facebook.com/mylesr

www.twitter.com/myles111us

 

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Originally posted by myles111:

Originally posted by NMcGuitar:

Myles,

I have a Tube Works Smooth 303 pedal, which contains (so they say) a 12AX7 tube - I have no idea what kind. I have never been too thrilled with the tones (trebble is kind of brittle, bass is a little mushy, etc.). I just wanted to add a little tube warmth to my sound, and a touch of overdrive.

Do you know if it is even worth it to open this thing up, find out what tube is in there, and maybe replace it? Or should I just sell it on Ebay?

 

Thanks for any advice you might have!!

NMcGuitar ...........

 

Before you sell it and take a beating, stick a 12AX7C in there. They are less brittle and much more warm and linear.

 

If you are in the L.A. area, let me know, I will give you one for free that I would hand select for you. Sorry, but I don't have enough hours in the day to mail stuff, no matter what folks offer to pay.

 

You can also maybe find somebody in L.A. if you are not here, work some sort of deal with them, and I'd be more than happy to give them the tube to send to you ...........

 

OR ............ you can contact Ludovic Pierson at www.tubecellar.com who is in LA that I see all the time, work out a deal with him that if I give him the tube, you'd pay him to box and ship it maybe.

 

Any of the options is fine ...........

 

Or ......... contact Doug Preston as www.dougstubes.com and he might sell you one real cheap, just tell him that on his VTV tester, to find you a 12AX7C that reads BELOW 95. He has a lot of great stuff.

 

In any case, any of these sources should be between free and less than $10.00, so try that before selling it.

Thanks for the advice, and the offer! Since I'm in Washington DC, I guess I'll give Doug Preston a try. I'll let you know how things work out.

May all your thoughts be random!

- Neil

www.McFaddenArts.com

www.MikesGarageRocks.com

 

 

 

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Originally posted by NMcGuitar:

Originally posted by myles111:

Originally posted by NMcGuitar:

Myles,

I have a Tube Works Smooth 303 pedal, which contains (so they say) a 12AX7 tube - I have no idea what kind. I have never been too thrilled with the tones (trebble is kind of brittle, bass is a little mushy, etc.). I just wanted to add a little tube warmth to my sound, and a touch of overdrive.

Do you know if it is even worth it to open this thing up, find out what tube is in there, and maybe replace it? Or should I just sell it on Ebay?

 

Thanks for any advice you might have!!

NMcGuitar ...........

 

Before you sell it and take a beating, stick a 12AX7C in there. They are less brittle and much more warm and linear.

 

If you are in the L.A. area, let me know, I will give you one for free that I would hand select for you. Sorry, but I don't have enough hours in the day to mail stuff, no matter what folks offer to pay.

 

You can also maybe find somebody in L.A. if you are not here, work some sort of deal with them, and I'd be more than happy to give them the tube to send to you ...........

 

OR ............ you can contact Ludovic Pierson at www.tubecellar.com who is in LA that I see all the time, work out a deal with him that if I give him the tube, you'd pay him to box and ship it maybe.

 

Any of the options is fine ...........

 

Or ......... contact Doug Preston as www.dougstubes.com and he might sell you one real cheap, just tell him that on his VTV tester, to find you a 12AX7C that reads BELOW 95. He has a lot of great stuff.

 

In any case, any of these sources should be between free and less than $10.00, so try that before selling it.

Thanks for the advice, and the offer! Since I'm in Washington DC, I guess I'll give Doug Preston a try. I'll let you know how things work out.
I think you will be very happy with Doug - his quality and especially his prices. I don't think there is actually anybody cheaper, and folks that are more don't test nearly as well or have the equipment he has.

Myles S. Rose

www.guitaramplifierblueprinting.com

www.la-economy.blogspot.com

www.facebook.com/mylesr

www.twitter.com/myles111us

 

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Hey Myles, in light of my recent decision, to try EL84's and Yellow Jackets in my Hot Rod DeVille, I have been advised to change my pre amp valves in order to get the best results from the YJ's.

I have also been told that I should use a different type in the 'phase inverter'(?) position, (Thanks Caevan!) I currently use three EH 12AX7's in there.

Can you advise on what I should replace them with? Where might be the best source?

If it is of any help I am hoping to give my amp a warmer tone, I use mainly an overdriven sound from the clean channel which I vary from the guitar. Currently it is a touch thin for lead work.

Many thanks in anticipation of your assistance.

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Originally posted by Teahead:

Hey Myles, in light of my recent decision, to try EL84's and Yellow Jackets in my Hot Rod DeVille, I have been advised to change my pre amp valves in order to get the best results from the YJ's.

I have also been told that I should use a different type in the 'phase inverter'(?) position, (Thanks Caevan!) I currently use three EH 12AX7's in there.

Can you advise on what I should replace them with? Where might be the best source?

If it is of any help I am hoping to give my amp a warmer tone, I use mainly an overdriven sound from the clean channel which I vary from the guitar. Currently it is a touch thin for lead work.

Many thanks in anticipation of your assistance.

Teahead........

 

First off, try the Yellow Jackets without changing anything else. Don't make a lot of changes too fast, you won't know what did what.

 

The Yellow Jackets are pretty cool as they are, and you do not need to change things to make them do their magic.

 

Second, the 12AX7EH's are great tubes, and I see no reason to change them, unless you have some sort of problem with them.

Myles S. Rose

www.guitaramplifierblueprinting.com

www.la-economy.blogspot.com

www.facebook.com/mylesr

www.twitter.com/myles111us

 

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Myles - I've NEVER replaced the tubes in my Marshall JCM 900, and I must admit I have no idea what I'm doing.

 

I live in L.A. What do you recommend I get, where do you recommend I get it (them), and how the heck do I do it?

 

Thanks!

 

-kid music

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Myles,

 

What's the advantage of running high plate voltage in an amp? It seems like all the modern high gain amps (Mesa Rectifiers, Peavey, Soldano) are up around 475-500 volts. I know that this isn't necessarily new, I've read about the old MusicMan & Ampeg amps that have even higher plate voltage, but it seems like the current amps all are going in this direction. Would it be possible to have a high gain, heavy sounding amp running something like 350v?

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Hi Myles,

 

I gig with a mesa Blue angel head into a mesa duo bin with celestion v30s and a closed back.

 

I've been unhappy with my sound over the last few gigs, and I'm wondering if the (original mesa)tubes are getting a little long in the tooth. I'm wondering what to replace them with. The angel runs 38 watts class a, with two 6v6s, four el84s and 5 12ax7s, plus a rectifier tube (can't remember what kind).

 

If at all possible, I'd like to maximise clean headroom available, as sometimes my setup can't quite stay clean enough in certain rooms. Is this possible through tube choice, and are there tonal tradeoffs?

 

If it's unlikely that I can't get any more clean headroom, what possible avenues for modification can I pursue? an extra power stage that I can switch in and out if needed would be great, but am I right in assuming that would need an extra transformer?

 

thanks in advance,

 

Martin

"Funk is it's own reward."- George Clinton
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Hello, Myles! I was hoping that you could help me with this one.

 

I've had my Mesa Maverick 4x10 for about a year now. I enjoy the tone of it, matched with my PRS CE-24. Since it is a class A amplifier, I know that it will be time to replace the tubes before long.

 

Does anyone have suggestions about what might be some good replacement tubes (pre-amp & output), when the time comes? Will I need to stay with Mesa replacements, or would it be better to look at some alternatives?

 

Thanks! :thu:

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Originally posted by kid music:

Myles - I've NEVER replaced the tubes in my Marshall JCM 900, and I must admit I have no idea what I'm doing.

 

I live in L.A. What do you recommend I get, where do you recommend I get it (them), and how the heck do I do it?

 

Thanks!

 

-kid music

Kid Music -

 

First ... there are tons of places in L.A., to get tubes.

 

Just call your favorite store, I am sure that can give you some great ideas.

 

As far as the type .... read my tube primer document, as this boils down to personal taste.

Myles S. Rose

www.guitaramplifierblueprinting.com

www.la-economy.blogspot.com

www.facebook.com/mylesr

www.twitter.com/myles111us

 

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Originally posted by steve f:

Myles,

 

What's the advantage of running high plate voltage in an amp? It seems like all the modern high gain amps (Mesa Rectifiers, Peavey, Soldano) are up around 475-500 volts. I know that this isn't necessarily new, I've read about the old MusicMan & Ampeg amps that have even higher plate voltage, but it seems like the current amps all are going in this direction. Would it be possible to have a high gain, heavy sounding amp running something like 350v?

Steve ....

 

Generally, higher voltages would give more power. BUT, tubes love current more than voltage, so running a tube at 400v and a higher current may be a lot better than 500v and lower current (this all must be kept in balance).

 

Higher voltage amps at times sound more harsh. Listen to a tweed Bassman, that is a great balance of voltage and current. Lower plate voltages also generally produce less noise, longer tube life, and wider frequency response.

Myles S. Rose

www.guitaramplifierblueprinting.com

www.la-economy.blogspot.com

www.facebook.com/mylesr

www.twitter.com/myles111us

 

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