Thoughts on Jimmy Page’s Super Bass Marshall?

[Reeltarded]

the phase inverter uses a 12au7 here (both the original and the recraeations).

This is part of the 180w mod on a 1959 model to partial Major mod 1967.

Jimmy Page's sound is much like a JTM-afied Major at about 4-5 on the volume. That completely makes sense.

[Mark]

the phase inverter uses a 12au7 here (both the original and the recraeations).

This is part of the 180w mod on a 1959 model to partial Major mod 1967.

Jimmy Page's sound is much like a JTM-afied Major at about 4-5 on the volume. That completely makes sense.

I know nothing about this mod, do you mind sharing this information?
Thanks for your help.

[cdemike]

I haven't heard enough to say whether I think it or the MSG100 sounds closer, and I'm not convinced the Super Dragon is closer to what the amp was in 1973 versus the Royal since Page's amp was continuously modified throughout the 70s; given that the Super Dragon is ostensibly a clone of what Page's amp is like now or a slight variation thereof, I'll be interested to hear what clips will come out of these amps.

In any event, I'm surprised by how the new amp sounds with the 12AU7 in the PI -- much dirtier than I anticipated. I've seen 2 versions of the Major driver: one with 39k plate resistors and a shared 2k7 cathode resistor on a schematic dated 1968 and one with 47k plate resistors and a shared 1k5 cathode resistor on the 1970 Unicord schematic. Doing some quick load line math with an assumed B+ of 350V (closer to what I anticipate the PI node would be on an amp based on a 1992 or 1959 than in a Major), this is what I get for the early and late versions:
1968 version:
Va = 220V
Vk = 9V
I = 3.3mA

1970 version:
Va = 165V
Vk = 5.9V
I = 3.9mA

The 1968 version is much closer to center-biased. According to all the press materials Sundragon has been circulating, Page asked Tony Frank to increase the amp's headroom, so he ostensibly would have gone with something closer to center-biased. Assuming the tail resistance remains the same, the load line indicates that with both sides of the PI using 39k plate resistors, bias voltage would be approx 7.5V, plate voltage would be approx 240V, and 102V drops across the tail with 350V at the PI node.

That said, there's also not a ton of difference in gain between these two setups (cheated on this one and used the ampbooks.com LTP calculator), with a 12AU7 LTPI with Ra = 39k + 47k and Rk = 2k7 yielding an inverted voltage gain of 6.92 and 7.06 non-inverted voltage gain. Values closer to the 1970 version (Ra = 47k + 56k and Rk = 1k5) yielded an inverted voltage gain of 7.24 and 7.10 non=inverted voltage gain. Both of those assume 220k grid leak resistors. Dropping those down to 56k with the 39k/47K+2k7 setup drops gain to only 6.43 and 6.47 (~93% of the 220k figure). I'm guessing the grid leaks may have been reduced to keep the KT88s/6550s happier and reduce blocking distortion, but based on how little bass Page dialed in, I wouldn't be terribly surprised if they kept them higher (doesn't seem like he would have encountered a ton of blocking distortion).

This all assumes that the Sun Dragon amp doesn't make concessions to what Mitch Colby reads to be the average consumer buying those 50 amps. If it were Marshall or some other larger-volume manufacturer, it seems like the wisdom might be to accommodate buyers who turn the bass control way up, when it sounds to my ears that Page never passed 4 or 5/10 on the bass knob in the 70s.

I'm interested in experimenting with a 12AU7 in my amp's phase inverter -- will report back if I do. I have tried swapping 12BZ7 and 12AT7 in a 12AX7's stead in my amp without any value changes and I found the amp sounded further away from my goal posts at least (circa 1973 sounds), though I did like the 12BZ7. Less honk/quack but more clarity.

[Roe]

Great post! I'd try lowering anode resistors towards 16.5k and 18k or higher. And 1k anode and 14k tail.

Also, try a higher driver voltage for more punch

[Reeltarded]

Page's whole thing is volume and it never starts to sing. So blaring and midrange.

And open. BANGING THE HELL out of everything.

[Reeltarded]

the phase inverter uses a 12au7 here (both the original and the recraeations).

This is part of the 180w mod on a 1959 model to partial Major mod 1967.

Jimmy Page's sound is much like a JTM-afied Major at about 4-5 on the volume. That completely makes sense.

I know nothing about this mod, do you mind sharing this information?
Thanks for your help.

His heyday sound with the first version of the 100s turned into 180s sound like a generally mild JTM shared cathode with a giant bypass on the volume control, warmer and wider than a Major but similar hammer strike. heh

[Roe]

This is part of the 180w mod on a 1959 model to partial Major mod 1967.

Jimmy Page's sound is much like a JTM-afied Major at about 4-5 on the volume. That completely makes sense.

I know nothing about this mod, do you mind sharing this information?
Thanks for your help.

His heyday sound with the first version of the 100s turned into 180s sound like a generally mild JTM shared cathode with a giant bypass on the volume control, warmer and wider than a Major but similar hammer strike. heh

agreed. with a 5nf bright cap and the volume below 6 you get close with a very powerful 100w amp. Also, you really need those thin bass strings, like 22-30-38

[Roe]

Listening to How the west was won (1972 recording) again on some unforgiving speakers does give a clear impression of 500+v and 6550s (or similar), not el34s and 460v by any chance

[Reeltarded]

Super tight. Like a gnarly Twin Reverb, sometimes even a UL model. It just goes over every top without being especially grinding.

It accounts for some of the slop, because it takes balls and a lot of attitude to stick yourself out there with a 2 ton direct box.

There is a little bit of a blonde Fender in there, at least you can get a similar feel from a somewhat underdriven blondey at a volume that doesn't bruise the 5th row.

I have always thought people who wanted to sound like an average of Jimmy Page don't really want an average Marshall but instead some Fender amp.

[Roe]

I'd start with this 1970 unicord superbass schematic showing how to implement 6550s:

Add a 5nf bright cap
12au7 in v3
decrease v3 plate resistors to 47k (allen bradleys)
increase 470r cathode to 1.5k (cf. https://www.drtube.com/schematics/marshall/1967u.gif)
decrease NFB slightly

[didit]

Beware and have care Miles —

There is a little bit of a blonde Fender in there, at least you can get a similar feel from a somewhat underdriven blondey at a volume that doesn't bruise the 5th row.

There are serious if curious elements within TAG flaunting pictured forks who’ve rejected existence of any “blonde” Fenders.

Be aware and mildly cautioned.

Best ..

[Mark]

This is another similar thread to this one. Both thread may assist someone.

https://ampgarage.com/forum/viewtopic.php?t=31450

[Mark]

Super tight. Like a gnarly Twin Reverb, sometimes even a UL model. It just goes over every top without being especially grinding.

It accounts for some of the slop, because it takes balls and a lot of attitude to stick yourself out there with a 2 ton direct box.

There is a little bit of a blonde Fender in there, at least you can get a similar feel from a somewhat underdriven blondey at a volume that doesn't bruise the 5th row.

I have always thought people who wanted to sound like an average of Jimmy Page don't really want an average Marshall but instead some Fender amp.

I wonder if it’s possible to build a low wattage version and still have the sound?

The amp would weigh a ton and be deafening loud. I’m not a fan of putting KT-88’s in a Marshall using the stock transformer set as they have to be biased very cold and they really don’t sound better than EL-34’s in my opinion.

[Roe]

I wonder if it’s possible to build a low wattage version and still have the sound?
The amp would weigh a ton and be deafening loud. I’m not a fan of putting KT-88’s in a Marshall using the stock transformer set as they have to be biased very cold and they really don’t sound better than EL-34’s in my opinion.

Not really in my experience. but attenuators do work. and the page sound does not require much distortion. and its is 6550As here

[cdemike]

Just remembered this thread from a little bit ago: https://www.mylespaul.com/threads/ox-bo ... 989/page-2

There are a few posts from a guy (Pierce103) who spent some time with Jimmy Saukrai ("Mr. Jimmy"), who I think I has gotten closest to "the sound" across the Marshall years (I still think that Eric from Royal got really close to the MSG sound). Sakurai's amp was running JJ EL34s and 3x 12AX7's. Not to throw a wrench in things, but worth considering. A brief gut shot of the amp (a heavily modified /A series Super Trem) is visible in the Mr. Jimmy movie showing a pretty weird setup inside, but it looks to me like a 33k slope resistor (see post 90 for the screenshot in question: https://www.thegearpage.net/board/index ... n.2516038/). "Weird stuff" being series Orange Drop and what appears to my eyes to be a Sprague Black Beauty capacitor as V1 coupling cap for the normal channel, peaking resistors across both mixing resistors (wouldn't this basically add a low pass filter on the bright channel? How would the resonant frequency of the peaking network change, if at all?), and parallel ceramic caps in the tone stack (presumably parallel 10nF as has been documented in other amps from around the same serial number).

Speaking of serial numbers, Sakurai's amp is very close to Page's amp in terms of serial numbers (Sakurai's amp is ST/A 10057 and Page's amp is SB/A 10053). I'm not sure what production run timing looked like at Marshall in late 1968, but given that Marshall made lots of component substitutions over the years pending on-hand parts availability, some things in this amp that appear original might be clues as to what was in Page's amp. It doesn't look like there's a ton of red "warranty" paint left over the solder joints, but the 10k CC dropping resistors appear to be stock (and per schematic), there appear to be per-schematic factory PI cathode and grid leak resistors, and to my eyes the parallel ceramic tone stack caps appear like they may also be stock. Not sure if that last piece reflects broader 22nF Mustard availability at that moment in history at the Marshall factory, but that might support coupling cap value substitution(s) -- I'm specifically speculating that the bright channel used a 2n2 coupling cap based on what I've heard in my own amp.