Joe Walsh Mods

[purpletele]

This may need to be moved but I thought it was worthy of presenting the info:

I am pretty close to the Dr. Z Community and heard some interesting strategy and thought I would share.

Joe Walsh is one of the original big artist to represent Dr. Z Amps from the Hell Freezes Over Reunion.  They have been together since.

He is a big Electronics guy and Ham Radio Operator so it is supposedly not surprising to have him call up and request a new configuration.

Joe prefers the Z-Lux paired with a Deluxe Reverb, however for this show they were trying to become more accurate with the mic's and multiple discipline back up musicians, so Joe asked for his Maz 8 to have an upgrade.

The Maz 8 is a scaled down Maz 38/18 with one EL84 Power Tube.  Great amp!!

Joe requested a PSE or an added parallel EL 84.  Now I thought that is pretty cool.  So the Dr. Z amp that you see him playing on Late Night shows is the prototype for a new Maz 8.

I think the Player interaction between Brad Paisley, Walter Becker and Joe Walsh is fascinating to watch.

BV

[pompeiisneaks]

Very cool, I just worked on a Dr Z 38 Senior with some reverb issues, and I do like the quality of the build.  The only thing I didn't like too much was that board, man it's HUGE, covers everything, so accessing things underneath is pretty much a royal pain in the butt.  I did get the issues sorted, but man working on them isn't fun.  If the problem is right on top, super easy of course.  That was one problem, the reverb recovery resistor was making all kinds of noise, until I replaced it, and then the amp's original tank had been lost, so the one the guy put in really was feeding back badly inside the chassis.  I had to put two layers of cardboard on the top of it inside the bag to get it under control, but then it sounded great. 

~Phil

[purpletele]

Very cool, I just worked on a Dr Z 38 Senior with some reverb issues, and I do like the quality of the build.  The only thing I didn't like too much was that board, man it's HUGE, covers everything, so accessing things underneath is pretty much a royal pain in the butt.  I did get the issues sorted, but man working on them isn't fun.  If the problem is right on top, super easy of course.  That was one problem, the reverb recovery resistor was making all kinds of noise, until I replaced it, and then the amp's original tank had been lost, so the one the guy put in really was feeding back badly inside the chassis.  I had to put two layers of cardboard on the top of it inside the bag to get it under control, but then it sounded great. 

~Phil

Timely response, I am considering using a big board on the HoSo FX and I don't see any draw backs.  I am building a 4" x 16 board on paper, it goes into a 17 1/2 Chassis.  So far everything is exposed on my design, but good note for forethought.

I had read recently that MZ uses the MOD reverb tanks from Antique Electronics due to issues with the Belton or similar.

I bought a MOD tank for my Luckey Deluxe.

[MFowler]

Mike Zaite (Doc) and talked on the phone about stuff and he wanted to share with The Ampgarage his Dr Z Prescription (original Formula) board layout.  He emailed it to me to share but you guys are just as much a part of my life so here it is.


Mark

[purpletele]

Mike Zaite (Doc) and talked on the phone about stuff and he wanted to share with The Ampgarage his Dr Z Prescription (original Formula) board layout.  He emailed it to me to share but you guys are just as much a part of my life so here it is.


Mark

Wow,  that's cool.  I wonder if the 40 uF 500V cap is a Sprague, I bought one for the HoSo FX, it's gigantic, but it fits on my big board.

I haven't played that Z amp, I just know it is a Brad Paisley project. 

[pompeiisneaks]

Mike Zaite (Doc) and talked on the phone about stuff and he wanted to share with The Ampgarage his Dr Z Prescription (original Formula) board layout.  He emailed it to me to share but you guys are just as much a part of my life so here it is.


Mark

Wow,  that's cool.  I wonder if the 40 uF 500V cap is a Sprague, I bought one for the HoSo FX, it's gigantic, but it fits on my big board.

I haven't played that Z amp, I just know it is a Brad Paisley project.

I can tell you that one I just worked on had a huge Sprague as the first cap, I think it was 80/450 or 80/500 I can't recall though now, I did take video of it, so I could check when I get home (If I remember lol).

~Phil

[purpletele]

Mike Zaite (Doc) and talked on the phone about stuff and he wanted to share with The Ampgarage his Dr Z Prescription (original Formula) board layout.  He emailed it to me to share but you guys are just as much a part of my life so here it is.


Mark

Wow,  that's cool.  I wonder if the 40 uF 500V cap is a Sprague, I bought one for the HoSo FX, it's gigantic, but it fits on my big board.

I haven't played that Z amp, I just know it is a Brad Paisley project.

I can tell you that one I just worked on had a huge Sprague as the first cap, I think it was 80/450 or 80/500 I can't recall though now, I did take video of it, so I could check when I get home (If I remember lol).

~Phil

It's not a big deal, I attached my drawing showing the 40/ 500.  I haven't even searched, since I own one now, but I bet there are much smaller versions.

[MFowler]

This is the amp that Original Formula was used in.

[sluckey]

FWIW Hoffman lists the dimensions for caps on his order page. Should take the guesswork out of Visio layouts.

[purpletele]

This is the amp that Original Formula was used in.

Hey Mark, there's the 40 uF 500V cap I was referring to earlier.

Do you own that amp?

[purpletele]

FWIW Hoffman lists the dimensions for caps on his order page. Should take the guesswork out of Visio layouts.

I am getting my shapes set up as accurate as possible, I just modified my 40 uF 500 V Cap in Visio.  I haven't even looked to see if someone else makes a smaller one.  It doesn't matter its a cool looking cap and I have room on my board.

[sluckey]

Everybody else makes a smaller one at about 1/3 the cost. 

[purpletele]

Everybody else makes a smaller one at about 1/3 the cost. 

I was afraid to look around after I bought it.   Its one of those things where you buy things just to justify shipping so I grabbed parts and pieces for a couple of projects.

I could have sworn that the 40 uF 500 Cap was the same size as the Sluckey Shapes.  I'm sure there are 40 uF caps the same size as the shapes we are using.

So now that I think about it you have some responsibility for my giant 40 uF cap!  I am seeing a Blue 40 uF cap that I used from the templates, then when I was shopping I saw the Blue 40 uF cap, but did not focus on the size.  I assumed it was the standard Sprague 40 uF Cap.

That's funny, good thing is that it doesn't matter, I have it sized in correctly on the virtual board, and I'll use it on this amp,  It looks intimidating on this board.

[sluckey]

That blue 40µF/500V cap in my shapes stencil should be the size of the Sprague. The dimensions came from Hoffman.

[purpletele]

That blue 40µF/500V cap in my shapes stencil should be the size of the Sprague. The dimensions came from Hoffman.

I don't think I messed with my Visio setting on that particular cap until I received some parts.  The specs call for 1" x 2.38"  I measured 24 mm x 59 mm.

Maybe Doug had intended to use an Illinois or similar

My drawing has the Cap a little too wide but close.

The board is going to be 16" x 4 ", the transformers all both vertical mount so I should have ample room for tubes and controls.

I am working through my layout now, figuring out what needs to go to the top B + rail and then what gets connected on the second row.  Good challenge for me.

Plenty of room for the Blue Bomber 

[sluckey]

I don't think I messed with my Visio setting on that particular cap until I received some parts.  The specs call for 1" x 2.38"  I measured 24 mm x 59 mm.

The cap in my stencil is 1" x 2.31". Diameter is exactly as shown on your calipers. My length is 1/16" shorter than the real thing.

If your Visio cap is a different size you must have edited the stencil shape or resized it after dropping it on a drawing.

[MFowler]

This is the amp that Original Formula was used in.

Hey Mark, there's the 40 uF 500V cap I was referring to earlier.

Do you own that amp?

No I don't own a Prescription, I do own a Z Stangray head and Z 212 Celestion Alnico Blue and Gold speakers, great amp.  I've built a few Zwrecks and about 20 Trainwreck Rockets, a Route 66, Carmen Ghia, and soon a EZG50.

[jojokeo]

This is the amp that Original Formula was used in.

Mark,
I don't have a schematic do you? I may not need it? Can you confirm - after a quick look at that layout it appears to be a paralleled 12ax7 into a CF stage then LTPI into a quad of el84s?

[MFowler]

EF86 tube.


Note by Doc: The RXES has a full EQ and a EF-86 as a recovery stage.  The 3 dB boost runs on the EF-86, added by-pass cap to the cathode, for a nice FS lead boost. It uses negative feedback which keeps the amp tight  great for humbuckers. Also it uses a split load cathode bias so two differant pairs of EL-84's can be installed.  Yes a simple series loop can be fitted.  The Master is a dual ganged PPI type, with very little if any tone change.  The Brake-Lite will work with the stock RX ES, it will get hot..... but it will be fine


I suck at visio and since going with new PC I don't use it at all but I did something of a layout.


MODIFIED ABOVE TO NOTE THIS IS RXES NOT ORIGINAL FORMULA THAT USED ALL 12AX7

[jojokeo]

EF86 tube.


Note by Doc: The RX has a full EQ and a EF-86 as a recovery stage.  The 3 dB boost runs on the EF-86, added by-pass cap to the cathode, for a nice FS lead boost. It uses negative feedback which keeps the amp tight  great for humbuckers. Also it uses a split load cathode bias so two differant pairs of EL-84's can be installed.  Yes a simple series loop can be fitted.  The Master is a dual ganged PPI type, with very little if any tone change.  The Brake-Lite will work with the stock RX ES, it will get hot..... but it will be fine

Thanks again, however questions please (unless you have a schematic?):

1) I think he meant to say "the ef-86 'has' a recovery stage"?

2) The plate and screen on the ef86 is together so it's being operated in triode mode - is this how it's supposed to be?

3) What's with the 56k going to ground at the tone stack dropping resistor and 250pF point? Is that correct to the schematic? Never seen that before it is. That would put quite the load on the signal at that point losing a lot of gain especially with the recovery stage prior...thinking what would the point of that be (unless it's another way of dropping but unlike the two 220k's leaving from the ef86).

4) The recovery stage's cathode bypass cap goes to the switch then through a mislabeled 480r resistor? Something seems amiss there too?

[DummyLoad]

V2 in the image above is 12AX7 gain stage DC coupled to a CF. do y'all have a layout with EF86 as the recovery gain stage? also, that layout reads very "5F6-A bassman-ish" at least the preamp is.


footnote: missing 1M grid-leak at input jacks.

--pete

[MFowler]

There are I think 3 different versions of the RX, the original formula, RXES and one more.  The original formula uses 3 12ax7's.


Prescription
 NOTE: as of Fall 2004, this amp is no longer in production. It has been replaced by the Prescription Extra Strength.
 
 The Prescription is one of the Doctor's first amps, and its reputation will allow it to be one of the most popular Dr.Z amps for years to come. Players across the country have sung its praises, critics have gushed, and the word has spread. The Prescription is a British-voiced amplifier with its own distinct personality.
 
 The tone of this amp screams rock and roll when cranked, but when clean, its bell-like tone and piano-like clarity on the low notes gives excellent articulation on complex chords. The Prescription is complex and rich in harmonics, and gives incredible touch sensitivity and string-to-finger feel. So whether you're looking for clean and pretty, or crunch of doom for some rippin' blues slide, the 'Script may be the amp for you.
 
 Specifications
 Power Output: 45 Watts
 Output Tubes: 4 - EL84
 Preamp Tubes: 3 - 12AX7
 Rectifier: 1 - GZ34
 Controls: Volume, Treble, Mid, Bass, 3 way bright switch, expand switch, and footswitch Boost.
 Configurations: Head, 2-12 Combo & 1-12 Combo
 Colors: Black. Other custom wood finishes are available.
 Dimensions and Weight:
 Head: 19" W, 9 3/4" H, 9 1/2" D; 22 lbs.
 1-12 combo: 23" W, 20 1/8" H, 10" D; 47 lbs.
 2-12 combo: 27 1/2" W, 22 1/8" H, 10" D; 65 lbs.

[purpletele]

Thanks Mark,

Now I have Gas to build a Prescription variation.

Hobby security is suppose.  Stack up those projects like chord wood.