Feel free to ask Myles

[rsf1977]

Originally posted by myles111:

12AX7's especially when used in the MGH kit:

 

http://www.groovetubes.com/product.cfm?Product_ID=1737

 

These kits are also pretty agressive in even Fender Blackface and Silverface amps if you also use the supplied 12AX7 to replace the Fender 12AT7 in the PI position.

 

I am about a week or two behind though in building these kits.

Wow that's awesome! Do they make a high gain kit for mesa boogies that would be awesome!

[myles_rose]

Originally posted by rsf1977:

Originally posted by myles111:

12AX7's especially when used in the MGH kit:

 

http://www.groovetubes.com/product.cfm?Product_ID=1737

 

These kits are also pretty agressive in even Fender Blackface and Silverface amps if you also use the supplied 12AX7 to replace the Fender 12AT7 in the PI position.

 

I am about a week or two behind though in building these kits.

Wow that's awesome! Do they make a high gain kit for mesa boogies that would be awesome!

This kit is also used in Mesa amps, Bogner, Rivera, and many others. V1, V2 and the phase inverter. I have these in a lot of Mesa amps.

[rsf1977]

This kit is also used in Mesa amps, Bogner, Rivera, and many others. V1, V2 and the phase inverter. I have these in a lot of Mesa amps.

Awesome just emailed Groove Tubes about it, thanks Myles!

 

ryan

[myles_rose]

Originally posted by rsf1977:

This kit is also used in Mesa amps, Bogner, Rivera, and many others. V1, V2 and the phase inverter. I have these in a lot of Mesa amps.

Awesome just emailed Groove Tubes about it, thanks Myles!

 

ryan

Ryan,

 

I was the one that probably just answered your email! I would also be the one to build the kit.

[FormerOceanwaySlave]

[bump]

[myles_rose]

Originally posted by daklander:

Hello Myles,

Jeez, this brought all kinds of things to mind...

 

I'll be polite.

 

I'm happy to have you put up a specific post to make it easier to get to your info about amps & such.

 

Now, can you help me play better to sound better through any amp????

 

Dak ...

 

Your avatar is great.

 

Come back to L.A and I will do what I can for you.

[Caevan O’Shite]

rsf1977/Ryan:

 

Just thought I'd throw in my two-cents here:

 

I loaded my little Carvin Vintage 33 amp with a GT/MHG kit, and it did wonders for it on both its "clean" and "soak" (overdrive/distortion/"lead") channels.

 

A very important thing to look for in a tube for the phase-inverter/driver position is a "Matched Phase Inverter", abbr. as "MPI".

 

The nine-pin mini tubes (12AX7, -AT7, -AU7, etc.) are all dual-triodes, kind of like two tube assemblies in one bottle. (One of the reasons that they're so prevalent.)

 

If a 9-pin mini dual-triode tube is tested and found to have very similar characteristics in both of its internal triodes, it will serve exceptionally well as a phase-inverter/driver, as many amp designs split the signal here through both triodes.

 

If they match well, response will be even with good, strong fundamentals and overtones; if not, phase-cancelations and resonances can make for weird, un-even response across or up the fretboard, and even perceived "dead-spots" here and there along the guitar's range.

 

The GT/MHG kit, a good GT MPI for the phase-inverter, and Myles' recommendations for the other tubes (like the reverb position) made a HUGE difference in my amp!

[mherrcat]

What did I do to my amp? ('74 SFTR)

 

I had the chassis out and was re-biasing using a Weber Bias Rite. I wanted to check the power tube plate voltage directly with a multimeter. I believe I shorted pin 3 and pin 2 on one of the power tubes; the tabs were VERY close on that tube and either the probe slipped or I flexed the tab and the two tabs contacted.

 

 

Anyway, sparks at the point of contact, but, here's the weird thing, sparks also on the other end of the chassis at or very near V1.

 

The amp works but there is a constant buzz. Increases and decreases with volume adjustment.

 

Someone suggested that maybe I had put the full plate voltage onto the heater string and damaged some or all of the preamp tubes. I swapped out ALL the preamp tubes with known good tubes and still had the buzz.

 

Any ideas or suggestions appreciated. Also, any recommendations for a good/honest/reliable amp tech in West LA or the greater LA area appreciated.

 

Thanks!

 

Mark

 

(P.S. I hear ya'll snickering out there...)

[myles_rose]

Mark,

 

Yes, you put about 475 volts DC on the AC heater. You may have an issue with the AC winding in the power transformer but it may be as simple as a preamp tube messed up.

 

Grab a spare 12AX7 and try swapping it in each position starting with V1.

 

If that does not fix it (there may be more than one of them bad) then it may be best for a tech.

 

A great tech is Steve Dikun (Rock and Roll Doctor) in Burbank. On the west side, call Ken Daniels at TrueTone music and get the number of one of their techs. He uses two and both are terrific.

 

Steve Dikun's info is here off the techs area of my own website so excuse the formatting from my copy and paste:

 

Rock N' Roll Doctor - Steve Dikun

Maybe no website but who cares, this is a strong recommendation. If you want any blueprinting done on an

amp by me it better be in decent shape first. I don't have enough time to clean up mods that were not done

right or broken things unless you are already a blueprinting client. This is the first guy I recommend to

everybody in the So Cal area. If you have a amp problem or blew something up call Steve first.

Burbank / Glendale CA.

818-956-5413

[mherrcat]

It appears that the hum balance pot got zapped. I replaced it with the two 100 Ohm resistors on the pilot lamp and that seems to have fixed it.

 

[myles_rose]

Originally posted by mherrcat:

It appears that the hum balance pot got zapped. I replaced it with the two 100 Ohm resistors on the pilot lamp and that seems to have fixed it.

 

Congrats on your fix.

[pbognar]

Myles,

 

Question for you... I know you don't like amps with a load of preamp tubes, but I'm going to ask for some advice in the Boogie DC-3.

 

I remember playing one ages ago, and as much as I wanted it to be a versatile 2 channel 112 amp, I thought the clean side sounded real dark (I was hoping for an F-30 or Mark IV type of clean), the the drive channel was ok, but could have had more presence.

 

Their prices on the used market are pretty reasonable.

 

I was wondering if you had any tube suggestions to make the clean side more Fender like, which might also help tame the drive channel.

 

Also, most people seem to indicate that you should find one with a Vin30 in it...

 

If you think the amp is crap, do you have any other $400-$600 suggestions for a decent 2-3 channel 112 tube amp?

 

The third alternative is to get a Fender amp (even SS) and front-end it with a MI Audio Tube pedal, or Tone Lab. The MI Audio site demos their Tube pedal with a JC-120 and it sounds really great.

 

I guess it's easier to make a good clean amp to sound good dirty rather than the other way around...

 

btw - avatar is nice, but makes browsing the forum difficult at work...

 

Pete

[myles_rose]

Originally posted by pbognar:

Myles,

 

Question for you... I know you don't like amps with a load of preamp tubes, but I'm going to ask for some advice in the Boogie DC-3.

 

I remember playing one ages ago, and as much as I wanted it to be a versatile 2 channel 112 amp, I thought the clean side sounded real dark (I was hoping for an F-30 or Mark IV type of clean), the the drive channel was ok, but could have had more presence.

 

Their prices on the used market are pretty reasonable.

 

I was wondering if you had any tube suggestions to make the clean side more Fender like, which might also help tame the drive channel.

 

Also, most people seem to indicate that you should find one with a Vin30 in it...

 

If you think the amp is crap, do you have any other $400-$600 suggestions for a decent 2-3 channel 112 tube amp?

 

The third alternative is to get a Fender amp (even SS) and front-end it with a MI Audio Tube pedal, or Tone Lab. The MI Audio site demos their Tube pedal with a JC-120 and it sounds really great.

 

I guess it's easier to make a good clean amp to sound good dirty rather than the other way around...

 

btw - avatar is nice, but makes browsing the forum difficult at work...

 

Pete

Pete,

 

It is not the number of preamp tubes but the gain structure. Lots of tubes and it's added circuitry does have it's own issues but in this case it is the gain structure that is keeping you from getting to where you desire. There is little that can be done short of trying a 5751 in V1. For good 5751's hit www.kcanostubes.com

 

For a channel switcher in that price range, or a touch higher look at the two new Rivera amps.

 

Also check ebay.

[evets]

Myles,

As always, thanks for your selfless input here.

I just picked up a '67 blackface Bassman head. 'Haven't owned one since the seventies. It sounds as good as I remember! Still the power caps need to be replaced. (the telltale hum) I noticed that Torres offers a complete rebuild kit for the amp. ($98.00) Tonewise, my only gripe is I noticed an unusually healthy bit of hiss at higher gain levels. Is it premature to replace all the caps & resistors en masse?

[myles_rose]

Originally posted by evets:

Myles,

As always, thanks for your selfless input here.

I just picked up a '67 blackface Bassman head. 'Haven't owned one since the seventies. It sounds as good as I remember! Still the power caps need to be replaced. (the telltale hum) I noticed that Torres offers a complete rebuild kit for the amp. ($98.00) Tonewise, my only gripe is I noticed an unusually healthy bit of hiss at higher gain levels. Is it premature to replace all the caps & resistors en masse?

I would start with just the caps in the power supply.

 

If your amp has the original Astron tone caps keep those if at all possible. These are now fetching a lot of $$$$ at times and are hard to replace.

 

The power supply caps (under the cover) are usually all that need replacement.

 

The hiss is probably V1 and/or V2 that may be a bit tired (if original) and need to be cranked higher than necessary to get a given level. Maybe pull these for a minute and stick some generic fresh new 12AX7s in there and see if this does the trick. If it does, then find some good 12AX7s you like. Actually, try a spot check of each socket with a new tube one at a time.

 

Clean and lube the pots with real tuner/cleaner/lube stuff not something like WD-40 or just cleaner.

 

If you are close to L.A. I would be happy to do this for you at n/c and bias the puppy. I have a soft spot for Fender BF era amps.

[evets]

Originally posted by myles111:

Originally posted by evets:

Myles,

As always, thanks for your selfless input here.

I just picked up a '67 blackface Bassman head. 'Haven't owned one since the seventies. It sounds as good as I remember! Still the power caps need to be replaced. (the telltale hum) I noticed that Torres offers a complete rebuild kit for the amp. ($98.00) Tonewise, my only gripe is I noticed an unusually healthy bit of hiss at higher gain levels. Is it premature to replace all the caps & resistors en masse?

I would start with just the caps in the power supply.

 

If your amp has the original Astron tone caps keep those if at all possible. These are now fetching a lot of $$$$ at times and are hard to replace.

 

The power supply caps (under the cover) are usually all that need replacement.

 

The hiss is probably V1 and/or V2 that may be a bit tired (if original) and need to be cranked higher than necessary to get a given level. Maybe pull these for a minute and stick some generic fresh new 12AX7s in there and see if this does the trick. If it does, then find some good 12AX7s you like. Actually, try a spot check of each socket with a new tube one at a time.

 

Clean and lube the pots with real tuner/cleaner/lube stuff not something like WD-40 or just cleaner.

 

If you are close to L.A. I would be happy to do this for you at n/c and bias the puppy. I have a soft spot for Fender BF era amps.

Myles, you're a gem!

Actually, I'm on "the other coast" so I can't take you up on your generous offer, but thanks for your great suggestions. I'll be all about it as soon as I can get the power supply caps.

[myles_rose]

You are more than welcome SGH

[Stanimal]

Hi Myles,

Thanks again for you help getting the SAG-12AX7-M MPI for my Fender Hot Rod Deluxe. I now have the GT 12AX7-M in V1 and V2, and the MPI in V3. The amp sounds great - warm, fuzzy, articulate, and the More Drive channel is actually useful now, although I mostly use pedals for OD and distortion.

Never one to be satisfied, I am now wondering about the optimal bias setting for my power tubes. I put a set of GT 6L6C's with a hardness rating of 4 in to replace the original issue GT 6L6B red label. I lost a little clean headroom, which is OK.

Is there a 'best' bias setting for these tubes to have them performing at their optimum, and if so, what is it? I have a digital multimeter, so I can use that and the bias test point. I think Fender factory recommend is 60ma at the bias test point, while some say 68 or higher is best. I don't really want to chance burning up my tubes by constantly changing the bias setting.

Can you advise me on this? Thanks

Stan

[myles_rose]

Originally posted by Stanimal:

Hi Myles,

Thanks again for you help getting the SAG-12AX7-M MPI for my Fender Hot Rod Deluxe. I now have the GT 12AX7-M in V1 and V2, and the MPI in V3. The amp sounds great - warm, fuzzy, articulate, and the More Drive channel is actually useful now, although I mostly use pedals for OD and distortion.

Never one to be satisfied, I am now wondering about the optimal bias setting for my power tubes. I put a set of GT 6L6C's with a hardness rating of 4 in to replace the original issue GT 6L6B red label. I lost a little clean headroom, which is OK.

Is there a 'best' bias setting for these tubes to have them performing at their optimum, and if so, what is it? I have a digital multimeter, so I can use that and the bias test point. I think Fender factory recommend is 60ma at the bias test point, while some say 68 or higher is best. I don't really want to chance burning up my tubes by constantly changing the bias setting.

Can you advise me on this? Thanks

Stan

Stan,

 

You will not hurt the tubes by changing bias setting when you want. As long as you don't under bias too much so they run too hot you are safe.

 

I prefer Fender's 60mA setting personally. If you want more clean headroom you can get a nice matched 5751 from Mike at www.kcanostubes.com and this will give you yet one more cool option to swap in and out of V3. The 5751 is also very cool in V1.

[Stanimal]

Thanks Myles.

Under bias would be a lower number at the test point than a higher number?

You 'da man!

Stan

[myles_rose]

Originally posted by Stanimal:

Thanks Myles.

Under bias would be a lower number at the test point than a higher number?

You 'da man!

Stan

Stan,

 

An amp the is "underbiased" means there is not enough bias voltage on pin 5 of the output tube. So, the amp runs hot and you will see a higher milliamp reading using a bias probe.

 

In a Fender amp such as a Hot Rod with a bias test point, an underbiased amp will give a higher reading at the test point as that is showing plate idle current off pin 3 and not the bias voltage on pin 5.

[A7Xkid]

is there any way to eliminate feedback, other than turn down volume, switch to clean channel, and get further way, or dont use a pedal? i have a kustom dfx100 and a epiphone sg with a '57 clasic and an alnico v in it

[myles_rose]

Originally posted by A7Xkid:

is there any way to eliminate feedback, other than turn down volume, switch to clean channel, and get further way, or dont use a pedal? i have a kustom dfx100 and a epiphone sg with a '57 clasic and an alnico v in it

Turning it down or moving away is the way that works best.

 

Make sure your pickups do not need to be re-potted as this is common at times in some humbuckers and they become microphonic just like some tubes

[Caevan O’Shite]

Bemp for the minky...

[Caevan O’Shite]

> B U M P

[surgevw]

So I have a scratch built tube amp. 12AX7 preamp and inverter, diode rectifier, 6V6GT (from electro harmonix) push-pull with a transformer set for 16 ohms. I thought it was 8 ohms and have a 8 ohm Peavey Blue Marvel in it. I am going to add 7.5 ohms of resistance and a couple hundred microhenries in series to take care of this "issue" and quiet it down a bit.

 

My problem

 

I can't get even a warm overdrive without peeling paint of the walls. (BTW, I play a Strat, hard maple neck, with single coils). I am looking for at least a little bluesy overdrive.

 

After reading the book you helped write, and surfing your site some, it looks like 6V6-R output duet, maybe a 12AX7-C for preamp (?) and something different for the inverter (a 12AT7?)

 

Does this sound like a good starting point?

 

Any compelling reason for a tube rectifier, if I wanted to do such a mod?

 

Oh yeah, I have a single 5Y3 Sylvania USA rectifier tube kicking around, too.

 

Thanks,

Seth

 

 

P.S. I am gonna try to close the thread I started and leave this here.

[myles_rose]

Originally posted by surgevw:

So I have a scratch built tube amp. 12AX7 preamp and inverter, diode rectifier, 6V6GT (from electro harmonix) push-pull with a transformer set for 16 ohms. I thought it was 8 ohms and have a 8 ohm Peavey Blue Marvel in it. I am going to add 7.5 ohms of resistance and a couple hundred microhenries in series to take care of this "issue" and quiet it down a bit.

 

My problem

 

I can't get even a warm overdrive without peeling paint of the walls. (BTW, I play a Strat, hard maple neck, with single coils). I am looking for at least a little bluesy overdrive.

 

After reading the book you helped write, and surfing your site some, it looks like 6V6-R output duet, maybe a 12AX7-C for preamp (?) and something different for the inverter (a 12AT7?)

 

Does this sound like a good starting point?

 

Any compelling reason for a tube rectifier, if I wanted to do such a mod?

 

Oh yeah, I have a single 5Y3 Sylvania USA rectifier tube kicking around, too.

 

Thanks,

Seth

 

 

P.S. I am gonna try to close the thread I started and leave this here.

Seth,

 

There are way too many unknown aspects for me to attempt to answer. If you are blistering paint off walls a tube change is not going to do much. You need to look at your EQ and first gain stage.

[surgevw]

Perhaps blistering the paint was harsh. It was clean but too loud. I built a brake for it, so the speaker now only gets about 16% the power it used to. At least I can move the volume knob now so that all the change isn't in the first 30 degrees of motion. Maybe my best bet for overdrive is something like a tube overdrive pedal until I have a rehearsal space where I can crank this thing up.

 

Seth

[myles_rose]

Seth

 

I would need to see this amp.

[J J]

Myles,

I was just searching around and I came across the amp brand "B-52." They're really cheap for what you get.

 

Just wondering if you have any info on them...

thanks,

JJ

 

oh yea, here's the one i was looking at B-52 Stealth Series