Marshall Bluesbreaker

[Tiny_Daddy]

I want to build a Marshall JTM45 Bluesbreaker that is EXACTLY like the one used by Eric Clapton on the John Mayall Beano album. What schematic would this be?

Edit: I think this is it?

[Tone Junkie]

Tiny daddy I once embarked on that quest got close following a trail over at metro amp forum took me to a page of a guy changing one of the new reissued ones trying to get back to the sound of that one. he got real close . Saved all the information on my last computer it died and so did all my saved info.
If I get back over there I will try and retrace my steps. Contact Bill Wallace at marstran transformers or Wallace amplification.  Having the right transformers would be half the battle.
Bill

[Tone Junkie]

Oh and look at ceriatone for there jtm 45 he has a nice layout to look at. His schematic is the standard jtm 45 but it prints out well in layout form which makes it easy for me to write all my changes.
Bill

[tubenit]

Just an FYI

http://en.wikipedia.org/wiki/Marshall_Bluesbreaker

And a few paragraphs down ..... more info here:

http://www.gibson.com/en-us/Lifestyle/Features/Get%20That%20Tone_%20Blues%20Breakers/#

With respect, Tubenit

[xm52]

You might want to check out this book http://ampbooks.com/home/books/bassman/.

They discuss, in detail, the 5F6-A and the Bluesbreaker circuits.

[pullshocks]

I have the "Beano" CD out of the library right now--smokin'!!!!!  I can see why you want that tone.

Someplace I read that EC was using an external treble boost on that recording, you might want to check into that.

[FranciscoPerez]

Someplace I read that EC was using an external treble boost on that recording, you might want to check into that.

It was the Dallas Rangemaster with its mullard germanium transistor.
Check this out!
http://www.geofex.com/Article_Folders/Rangemaster/drm.htm

[Tiny_Daddy]

Thanks a lot guys! I have learned a lot. I am thinking the only place offering a vintage JTM45 output transformer is Mercury Magnetics
part number O45RS-L-8 part way down this page:
http://www.mercurymagnetics.com/pages/catalog/manufacturers/MM_Vox.htm
Here's trusting that they did it right.

I was planning on using a Hammond JTM45 power transformer. Any comments?
I don't see anyone stocking the 20Hy choke so I have asked Heyboer for a quote, 20Hy, 100mA. I have heard that the original choke was only 70mA?

Dallas Rangemaster: Some forum posts claim this was not used on the Beano album, that this is another "urban legend" that got started on the internet?

[mcrracer]

Magnetic Components have the trannies.
http://classictone.net/Marshall-Style-Transformers.html#anchor_1191
I have heard good things about them I have not had occasion to buy one yet.

[Tiny_Daddy]

Magnetic Components has the 20Hy choke too, and reasonable prices!  Thanks.

[Tone Junkie]

I really like mag.components iron especially for marshall type stuff. Bill

[Tiny_Daddy]

After much consideration here's the lineup:
Hammond power transformer, Heyboer 20hY 100mA choke, Magnetic Components output transformer.
Any advantage to SoZo mustard caps? They look like Mallory 150 and I would rather use a higher voltage rating than 400V.
One other thing: Does anyone know of a terminal board that includes the original tremolo circuit with the germanium transistor?

[Tone Junkie]

Tiny Daddy did you look at the layout at ceriatone. it has the tremolo circuit. Sad thing is i had a ceriatone chassis and faceplates exact copy of the blues breaker .
 Decidied i wanted to go a differant direction tried to sell it on the sales page no bites so Ive proceded to make a hotrod marshall out of it cut some more holes in it already,  Sorry
Bill

[Tiny_Daddy]

Looking at Ceriatone, it seems they used the second triode as a follower and have a different arrangement on the pedal. Also it's on a separate board. Has anyone tried this circuit?

[sluckey]

I haven't tried the exact Ceriatone trem circuit, but many people here have. The Ceriatone circuit is a copy of the old Fender power tube bias modulation circuit (with a few component value changes) as seen in many of the old 6Gxx amps. Doug also uses this same circuit in his AB763 amps.

[Tiny_Daddy]

I have carefully collected various parts but have a question:
That 270pF capacitor in the tone stack: Ceramic, Mica or what is it?
Just one more thing, that cap on the lower end of the second volume control that parallels the 270K resistor: Is that 556P or just 56P, or what? Edit: After looking at other schematics, etc. I conclude it should be 500pF. Still don't know the dielectric. A photo of the original capacitors may help.

[bluesbear]

I'd say you can never go wrong using silver mica over ceramic. It's one of the few places that people say you can hear a difference where I hear it and am SURE I hear it. I don't care what was in Clapton's; it's never a good idea to purposefully make your amp sound worse.
Dave

[Tiny_Daddy]

Looking at the original Bluesbreaker board picture on www.turretboards.com , the 270p cap is a rectangular box, maybe a molded mica?

edit: Sorry, I was trying to post a response & accidentally "modified" TD's post. I have done my best to reconstruct it as best I can remember.   

Geezer

[Geezer]

I love those old "domino" mica caps.......sweetest caps around, and out of the dozens I've pulled from old equipment, I've never found a single one to be leaky, even after 50-60 years!

G