Feel free to ask Myles

[myles_rose]

Originally posted by api4u:

Hi, Myles,

 

I just picked up a used Dr. Z MAZ 38 Studio Lead head, and Z-Best ported Thiele cab, w/ V30 and G12H drivers.

 

The amp has quite a bit of hum, even when instrument cable is not plugged in. I've tried changing the speaker cables, the power source locations, the pre-amp tubes, spritzing out the pots w/ Caig, unplugging the reverb, and changing to a different speaker cab, all with the same hum. I emailed the previous owner, and he said he had noticed it, but it didn't bother him; to me it is an unacceptable level of hum.

 

I'd always heard how quiet the "Z's" are, and suspect a defective part or ground somewhere. Can you offer a diagnosis path you'd start with, to try to eliminate the hum? Perhaps a website outlining diagnosis techniques for the x-formers, caps, tubes, etc? I'm hoping to not just keep replacing parts, just to find out that's just the nature of this particular model. Any previous experience with this head-type?

 

Oh - I've also plugged my Two Rock Custom into the same outlets, and it's dead quiet - so it's not an externally caused hum....

 

Thanks!

Steve

 

Steve,

 

This is a tricky one. Z amps are usually ultra quiet. Does the hum get louder and quieter when the reverb is turned up and down?

 

That is the first place I look as in the heads with reverb the pan is close to the transformers.

 

Let me know.

 

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

Myles S. Rose

 

Myles,

 

Yes, the hum does definitely increase, as the reverb is turned up. Also, There is a fairly loud "pop" when I turn it back onto stand-by, that is "amplified" by the reverb.

 

I unplugged the reverb cables, at the RCA connectors, but the hum is still there, although I don't hear the pop when I turn it off, then. The hum is a fairly low hum (sort of along the lines of a 60-cyle, but not as exaggerated) when the reverb is below 9 or 10:00; as I turn the reverb up past that, it introduces more of a hissing/swishing sound into the hum (I assume this is the reverb tube gain?).

 

I'm not sure what the tube position functions are, with this head, but if I pull V5 preamp tube, the hum disappears. I've tried a few different tubes in this position, with no noticeable difference.

 

Thanks, Steve

Steve,

 

V5 is the phase inverter and that is why the hum goes away ... everything goes away.

 

Mismatched output tubes can cause all sorts of hum issues. I change these about every 500 or so hours in these amps.

[api4u]

Hi, Myles,

 

I just picked up a used Dr. Z MAZ 38 Studio Lead head, and Z-Best ported Thiele cab, w/ V30 and G12H drivers.

 

The amp has quite a bit of hum, even when instrument cable is not plugged in. I've tried changing the speaker cables, the power source locations, the pre-amp tubes, spritzing out the pots w/ Caig, unplugging the reverb, and changing to a different speaker cab, all with the same hum. I emailed the previous owner, and he said he had noticed it, but it didn't bother him; to me it is an unacceptable level of hum.

 

I'd always heard how quiet the "Z's" are, and suspect a defective part or ground somewhere. Can you offer a diagnosis path you'd start with, to try to eliminate the hum? Perhaps a website outlining diagnosis techniques for the x-formers, caps, tubes, etc? I'm hoping to not just keep replacing parts, just to find out that's just the nature of this particular model. Any previous experience with this head-type?

 

Oh - I've also plugged my Two Rock Custom into the same outlets, and it's dead quiet - so it's not an externally caused hum....

 

Thanks!

Steve

 

Steve,

 

This is a tricky one. Z amps are usually ultra quiet. Does the hum get louder and quieter when the reverb is turned up and down?

 

That is the first place I look as in the heads with reverb the pan is close to the transformers.

 

Let me know.

 

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

Myles S. Rose

 

Myles,

 

Yes, the hum does definitely increase, as the reverb is turned up. Also, There is a fairly loud "pop" when I turn it back onto stand-by, that is "amplified" by the reverb.

 

I unplugged the reverb cables, at the RCA connectors, but the hum is still there, although I don't hear the pop when I turn it off, then. The hum is a fairly low hum (sort of along the lines of a 60-cyle, but not as exaggerated) when the reverb is below 9 or 10:00; as I turn the reverb up past that, it introduces more of a hissing/swishing sound into the hum (I assume this is the reverb tube gain?).

 

I'm not sure what the tube position functions are, with this head, but if I pull V5 preamp tube, the hum disappears. I've tried a few different tubes in this position, with no noticeable difference.

 

Thanks, Steve

 

Steve,

 

V5 is the phase inverter and that is why the hum goes away ... everything goes away.

 

Mismatched output tubes can cause all sorts of hum issues. I change these about every 500 or so hours in these amps.

Hi, Myles-

 

Man, I ordered the Groove Tubes Wednesday afternoon, and already got them, Friday afternoon! That's Service!

What should I check next (hopefully with a meter, rather than keep replacing parts - the rest of the parts should be measurable, I'd think). Is/are there any good websites that would walk me through checking out the various parts that I could check? Any particular parts you'd suspect, given the symptoms? Haven't tried this particular model before, but it also doesn't seem to really "dirty" up much, if that points to anything...if I crank the volume full power, and the master around 9:00 or 10:00, for a useable bedroom volume, it's still fairly clean, with a little crunch if I dig into, but not that much - maybe normal for this head, not sure - I would have thought it would dirty up quite a bit more with the volume fully cranked...

Anyway, if you've got any ideas, I'll try them out - was really wanting to love this amp, after all the great things I've heard here....

 

Thanks, muchly,

Steve

[Roger Forester]

Hey myles111, these questions probably shouldn't take you very long since they are noob questions.

 

Anyway, my question is basically can you explain to me this whole ohm thing? I have a MG100DX combo, and I want to upgrade soon, but I don't have enough money to get a cab and a head at the same time. So... my plan "was" to buy a cab, use it on the combo, then later get a head. The combo is 4 ohms, so what ohm of cab do I get? 4 also? And can I keep the 4 ohm cab for the head I plan on getting in the future?

 

Also, I was thinking of getting the Ashdown Fallen Angel 60 watt tube head(any good?), would that be loud enough for medium sized gigs? The cab is probably gonna be an avatar around 300 watts.

 

Thanks for helping people like me out.

[myles_rose]

Originally posted by Roger Forester:

Hey myles111, these questions probably shouldn't take you very long since they are noob questions.

 

Anyway, my question is basically can you explain to me this whole ohm thing? I have a MG100DX combo, and I want to upgrade soon, but I don't have enough money to get a cab and a head at the same time. So... my plan "was" to buy a cab, use it on the combo, then later get a head. The combo is 4 ohms, so what ohm of cab do I get? 4 also? And can I keep the 4 ohm cab for the head I plan on getting in the future?

 

Also, I was thinking of getting the Ashdown Fallen Angel 60 watt tube head(any good?), would that be loud enough for medium sized gigs? The cab is probably gonna be an avatar around 300 watts.

 

Thanks for helping people like me out.

Roger,

 

I may be missing something here.

 

Just make sure the cab ohms matches the amps.

[Vin-erator]

Originally posted by myles111:

Originally posted by Roger Forester:

Hey myles111, these questions probably shouldn't take you very long since they are noob questions.

 

Anyway, my question is basically can you explain to me this whole ohm thing? I have a MG100DX combo, and I want to upgrade soon, but I don't have enough money to get a cab and a head at the same time. So... my plan "was" to buy a cab, use it on the combo, then later get a head. The combo is 4 ohms, so what ohm of cab do I get? 4 also? And can I keep the 4 ohm cab for the head I plan on getting in the future?

 

Also, I was thinking of getting the Ashdown Fallen Angel 60 watt tube head(any good?), would that be loud enough for medium sized gigs? The cab is probably gonna be an avatar around 300 watts.

 

Thanks for helping people like me out.

Roger,

 

I may be missing something here.

 

Just make sure the cab ohms matches the amps.

Myles,

Isn't there an acceptable direction in which you can go? For example, I've been told that, if your head puts out 8 ohms, you can operate an 8 ohm cab or a 16 ohm cab, but, you can't go lower than the amp's minimum load and play an 8 ohm head through a 4 ohm cab.

 

Is this correct?

 

Thanks!

Vinny

[myles_rose]

Originally posted by Vinny C:

Originally posted by myles111:

Originally posted by Roger Forester:

Hey myles111, these questions probably shouldn't take you very long since they are noob questions.

 

Anyway, my question is basically can you explain to me this whole ohm thing? I have a MG100DX combo, and I want to upgrade soon, but I don't have enough money to get a cab and a head at the same time. So... my plan "was" to buy a cab, use it on the combo, then later get a head. The combo is 4 ohms, so what ohm of cab do I get? 4 also? And can I keep the 4 ohm cab for the head I plan on getting in the future?

 

Also, I was thinking of getting the Ashdown Fallen Angel 60 watt tube head(any good?), would that be loud enough for medium sized gigs? The cab is probably gonna be an avatar around 300 watts.

 

Thanks for helping people like me out.

Roger,

 

I may be missing something here.

 

Just make sure the cab ohms matches the amps.

Myles,

Isn't there an acceptable direction in which you can go? For example, I've been told that, if your head puts out 8 ohms, you can operate an 8 ohm cab or a 16 ohm cab, but, you can't go lower than the amp's minimum load and play an 8 ohm head through a 4 ohm cab.

 

Is this correct?

 

Thanks!

Vinny

I do not recommend mis-matching impedances.

[Vin-erator]

[/qb]

Myles,

Isn't there an acceptable direction in which you can go? For example, I've been told that, if your head puts out 8 ohms, you can operate an 8 ohm cab or a 16 ohm cab, but, you can't go lower than the amp's minimum load and play an 8 ohm head through a 4 ohm cab.

 

Is this correct?

 

Thanks!

Vinny[/qb]I do not recommend mis-matching impedances.[/QB]

Thanks Myles! I'm glad I asked.

 

Vinny

[myles_rose]

Originally posted by Vinny C:

[/qb]

Myles,

Isn't there an acceptable direction in which you can go? For example, I've been told that, if your head puts out 8 ohms, you can operate an 8 ohm cab or a 16 ohm cab, but, you can't go lower than the amp's minimum load and play an 8 ohm head through a 4 ohm cab.

 

Is this correct?

 

Thanks!

Vinny

I do not recommend mis-matching impedances.[/QB]

Thanks Myles! I'm glad I asked.

 

Vinny[/QB]

 

Vinny,

 

You are more than welcome.

[rzooff]

I've got some questions about my amp. It's JMP master model 50W, 2x12 combo.

 

What kind of them were originally installed in these amps? (I got greenbacks)

Is it model 2104? - there is no info about it on chassis...

Maybe You know

[myles_rose]

Originally posted by rzooff:

I've got some questions about my amp. It's JMP master model 50W, 2x12 combo.

 

What kind of them were originally installed in these amps? (I got greenbacks)

Is it model 2104? - there is no info about it on chassis...

Maybe You know

What is the serial number?

[rzooff]

Hello again

 

Serial no is: 09717K

[bluesswing]

Myles,

 

This question probably has been asked several times before but I would hesitate to read the whole thread to find the answer:

Do output tubes of the same type with different bias point (or gain) produce similar sound and overdrive characteristics in and around the clipping point, just the output volume level being different? I am especially interested in dual EL84 applications (Laney LC-15).

 

Thanks!

[myles_rose]

Originally posted by blues&swing:

Myles,

 

This question probably has been asked several times before but I would hesitate to read the whole thread to find the answer:

Do output tubes of the same type with different bias point (or gain) produce similar sound and overdrive characteristics in and around the clipping point, just the output volume level being different? I am especially interested in dual EL84 applications (Laney LC-15).

 

Thanks!

They react very differently and the dynamics and touch sensitivity differ.

[nayr]

Hi Myles -

 

I'm working on a project amp (ax84 november) and was wondering if you could tell me how to add a post-pi master volume. I've searched around and can't seem to find a schematic of one anywhere.

[myles_rose]

Originally posted by nayr:

Hi Myles -

 

I'm working on a project amp (ax84 november) and was wondering if you could tell me how to add a post-pi master volume. I've searched around and can't seem to find a schematic of one anywhere.

Writing detailed step by step instructions to modify an amp that was not designed to do this would be pretty time consuming.

 

Maybe call me on the phone during the week after 10am.

[Gabriel E.]

Myles,

 

I understand the importance of using a balanced dual triode for a phase inverter if the splitter is of the Shmitt(sp?) type found in most Fender and Marshall-type amps. In these amps, the two halves of the PI basically run in parallel.

 

However, my Super uses a concertina type where the two halves of the PI run in series. What's to be gained [pun intended ] by using a balanced PI in this situation?

 

Thanks,

 

Gabriel

[mdlestat]

Myles--

I'm going to ask you a question that I'm sure dozens of people have asked you before---perhaps even in this mega-thread. I'd search through all 65 pages for the answer, but I fear I'd pass out from all the reading I'd have to screen to find my answer

 

I am a new guitarist, and am seeking my first amp. It is overwhelmingly obvious that tube amps are superior to ss, but also seem to be pretty expensive overall compared to them...

 

I am a poor college student, working part time, with little in the way of expendable income.

 

What would your infinite wisdom recommend to someone like me in the vein of a lower-watt unit with a tilt towards rock, both modern and classic?

 

I do have a neighbor (duplex) so volume is somewhat of an issue---but not a defining restriction (I can practice when they're not home) and I don't have any gigging to worry about (for a few years, at my rate of learning, hehe)

 

Is there a solution in the tube world for someone like me, or should I just buy a ss unit?

 

Thank you so much in advance for your advice--

 

Matt

[myles_rose]

Originally posted by mdlestat:

Myles--

I'm going to ask you a question that I'm sure dozens of people have asked you before---perhaps even in this mega-thread. I'd search through all 65 pages for the answer, but I fear I'd pass out from all the reading I'd have to screen to find my answer

 

I am a new guitarist, and am seeking my first amp. It is overwhelmingly obvious that tube amps are superior to ss, but also seem to be pretty expensive overall compared to them...

 

I am a poor college student, working part time, with little in the way of expendable income.

 

What would your infinite wisdom recommend to someone like me in the vein of a lower-watt unit with a tilt towards rock, both modern and classic?

 

I do have a neighbor (duplex) so volume is somewhat of an issue---but not a defining restriction (I can practice when they're not home) and I don't have any gigging to worry about (for a few years, at my rate of learning, hehe)

 

Is there a solution in the tube world for someone like me, or should I just buy a ss unit?

 

Thank you so much in advance for your advice--

 

Matt

Matt,

 

This is all a very personal preference sort of thing but ....

 

The SS modelling amps are very cool. Many have headphone outs or with their built in patches and effects can sound really overdriven at very low levels. They are light weight (compared to a tube amp), need no tube swappage or bias adjustments, and are very versitile. You can cover the bases from clean jazz to the most heavy metal sounds.

 

Line 6 has the Spyder series, and Vox has some cool ones too. There are pretty upscale amps from these two folks and Fender too. They are all really excellent products and their price ranges overlap each other in each lineup so it boils down to which features you like more or even just which amp might look cooler or something.

 

In the studio they are really nice too. Too many folks misuse high wattage amps with a stage mic (SM57) and miss the boat. The greatest rock solos of all time were recorded on amps of less than 25 watts.

 

I amy be a tube sort of guy but this is more of a matter of the right tool for the job and a SS amp may be just the ticket. The modeling amps are in a different class than a small cheap solid state amp. Keep that in mind. I prefer the modelling amps generally but there are a lot of very nice SS amps that are not modelling amps. Fender has an amp line called Dyna Touch. These are worth checking out too.

[mdlestat]

Thank you so much for your advice, Myles--

 

I decided to get a Guitar Port for the time-being--- it may not be high-fidelity, but I figure it is along the lines of what you recommended--something that will at least give me an idea of the sounds I want to experiment with. I like the fact that it plays through my computer speakers--(Klipsch 4.1) which are pretty nice--- and also, at $99 bux, allows me to get to saving for some of the good stuff you have me drooling over in this thread here

 

Many thanks again--- keep up the great work

 

 

Matt

[archibald3]

Hey Myles here`s a post from the main forum maybe you can help point me in the right direction with.

 

I`ve got a Vanous.Its a hybred amp-solid state power -tube pre-amp.There`s 3 channels,one clean,2 overdrive.2 tubes in it[12ax7`s].The clean channel works fine but after about 1/2 hour of playing the drive channels both kind of fizzle down in volume to just barely audible.If i turn it off for a minute they come back but not for long.I replaced the tubes and it did the same thing-worked for about a set and then fizzled on the last song.Clean channel unaffected-works fine.Anybody have any idea what could be the source of the problem?I hate taking my amp in for repair blindly-with an intermittent problem like this.The only possible cause i can dream up is that when this first happened i noticed the output on my pedalboard had been cranked-so when i kicked in my solo boost[about 10db on top of the cranked output knob] it was hitting the amp pretty hard.It was during that set that this problem first occured-i didn`t notice the output knob having moved untill after the set was over. Arch

[myles_rose]

Originally posted by Gabriel E. vil:

Myles,

 

I understand the importance of using a balanced dual triode for a phase inverter if the splitter is of the Shmitt(sp?) type found in most Fender and Marshall-type amps. In these amps, the two halves of the PI basically run in parallel.

 

However, my Super uses a concertina type where the two halves of the PI run in series. What's to be gained [pun intended ] by using a balanced PI in this situation?

 

Thanks,

 

Gabriel

Gabriel,

 

nothing will be gained .... same for the PI in my tweed deluxe.

[myles_rose]

Originally posted by mdlestat:

Thank you so much for your advice, Myles--

 

I decided to get a Guitar Port for the time-being--- it may not be high-fidelity, but I figure it is along the lines of what you recommended--something that will at least give me an idea of the sounds I want to experiment with. I like the fact that it plays through my computer speakers--(Klipsch 4.1) which are pretty nice--- and also, at $99 bux, allows me to get to saving for some of the good stuff you have me drooling over in this thread here

 

Many thanks again--- keep up the great work

 

 

Matt

Matt,

 

Happy playing!

[myles_rose]

Originally posted by archibald3:

Hey Myles here`s a post from the main forum maybe you can help point me in the right direction with.

 

I`ve got a Vanous.Its a hybred amp-solid state power -tube pre-amp.There`s 3 channels,one clean,2 overdrive.2 tubes in it[12ax7`s].The clean channel works fine but after about 1/2 hour of playing the drive channels both kind of fizzle down in volume to just barely audible.If i turn it off for a minute they come back but not for long.I replaced the tubes and it did the same thing-worked for about a set and then fizzled on the last song.Clean channel unaffected-works fine.Anybody have any idea what could be the source of the problem?I hate taking my amp in for repair blindly-with an intermittent problem like this.The only possible cause i can dream up is that when this first happened i noticed the output on my pedalboard had been cranked-so when i kicked in my solo boost[about 10db on top of the cranked output knob] it was hitting the amp pretty hard.It was during that set that this problem first occured-i didn`t notice the output knob having moved untill after the set was over. Arch

This could be many things. The first thing I would look at is the heater supply for the preamp tubes. Dying out can be related to this.

[Gabriel E.]

Thanks!

[FormerOceanwaySlave]

[bump]

[Dank]

Myles: You have given a hearty thumbs up for the Pierson Champ Amp. It looks great for studio work. Given its price of $620.00, is it far superior to a '70's Fender Vibro Champ that can be bought on Ebay for a couple of hundred of bucks? Am I naively comparing apples and oranges? I will spend the extra money if its tone is that much better. Thank you for your time. Dan.

[myles_rose]

Originally posted by Dank:

Myles: You have given a hearty thumbs up for the Pierson Champ Amp. It looks great for studio work. Given its price of $620.00, is it far superior to a '70's Fender Vibro Champ that can be bought on Ebay for a couple of hundred of bucks? Am I naively comparing apples and oranges? I will spend the extra money if its tone is that much better. Thank you for your time. Dan.

Dan,

 

You are comparing apples to oranges. The tweed champ has but one tube in the front end where 1/2 of it is the gain stage (no tone control so no tone recovery stage to get back the lost gain) and the other half is the phase inverter to push the single output tube. There is very little between your guitar pickup and the speaker.

 

The speaker too .... 8" alnico speaker, and the match between the speaker and an output transformer that saturates in a very cool way in relationship to the speaker "crapping out".

 

A Champ is just amazing in the studio. Using a large diaphram great mic the amp sounds like a huge amp when recorded.

 

The later amps do not sound or play in the same way. I guess that is why good original Champs can go for over $1000 and more and even the great repros like the Clark and Victoria are in that same ballpark.

 

I have Victoria amps and I was going to get one of their Champs. I also love the one Mike Clark makes. Basically what swung me to the Pierson amp is that I had checked out over a dozen of these and they were so consistent that it was as consistant as a PCB amp. The sockets that Pierson uses for the output tube and rectifer are Belton sockets. These are not NOS or original style socket but a great industrial socket that does not rattle as many of the originals do. You can also throw tubes in and out of them for years. These are the same sockets that are used in the Maxi-Matcher which folks put tubes in and out off all day year after year.

 

The NOS tubes Pierson supplies .... they are always great. I have seen Telefunkens at times, orignal Mullards and the best NOS 6V6 tubes. For my amp I had him not supply the tubes as I have a lot of my own. This did not change the cost that much but I felt that I had enough tubes.

 

The amps were also very quiet. Most single ended class A Champs have a bit of hum. This is inherent in the design and most folks are not bothered by this much. Every amp I ever tested for Pierson amps had a VERY low noise floor, lower than any Champs I have ever had on a bench. I looked all over to see "his trick" but never discovered it. The caps are all the stock values and his wiring probably has some factor but nothing struck me as being unusual as his wiring was all very neat and tidy.

 

Most amp makers of these amps use pots made in Mexico. These pots are just fine and very good. Pierson's pots were CTS or some other orginal. Perhaps this had a little to do with the amp being as quiet as they are.

 

I play the amp just about every day. My wife prefers it over most of my other amps as it is not as loud. I guess that is a factor in amp selection for some people!

 

The Vibro Champ is a great amp but the plate voltage is higher on the output tube and the preamp tube. You have a lot more circuitry in the signal path, the speaker is voiced differently and the cabinet does not share that "how come this thing sounds like it has reverb" quality of the tweed cabs.

 

Both are great amps.

[Dank]

Myles: Thank you for your prompt and informative reply. You made my choice easier. I have a Fargen Bastage and THD 2x12 coming next week; the Pierson will be my next purchase. Dan.

[cheesey]

hi Myles, you recommended Mike at KCA for tubes re my Tweed Super. Mike helped me out and I ended up leaving the JJ 6L6's and he sent me nos rca 12ax7 for v2,v3 and nos ge jan phillips 6072 for v1.

the amp sounds great.

 

when you use your vicky 20112 do you jumper the channels? how do you set everything say you wanted

a good blues tone?

 

i have tried leaving the normal channel volume one notch lower than the bright channel volume.

it would be good if i could use my guitar volume to go from clean to grind but I really lose clarity when i turn down the volume. I have Lindy fralin pups, same ones used by Bill Callaham in his vintage strat repros. They came with a tone cap , had it installed and maybe they screwed up.

I am kinda getting it but still havent dialed it in yet . tried dropping the treble and raising the presence.

 

Guess I am just wondering how other tweed guys dial in their sound.

thanks again for your help

tim

[myles_rose]

Originally posted by Dank:

Myles: Thank you for your prompt and informative reply. You made my choice easier. I have a Fargen Bastage and THD 2x12 coming next week; the Pierson will be my next purchase. Dan.

Dan

 

You are welcome.

 

By the way, the THD 2x12 is a killer cab! Try it where you would normally think of using a 4x12 Marshall type cab. You may find it pretty interesting.