Is it worth it? Marshall UPGRADE to 560V (PT) + 2.1K-3.3K (OT) + 3H/250mA (Choke)

[StanHavars]

There we go with another crazy idea

Planning an iron upgrade on my SLP reissue and looking for real-world input.

Target specs & parts:

• B+ 560V (Mercury MP100-67S) PT
• OT primary 2.1K-3.1K (Mercury O100RS-LM) OT
• Choke 3H / 250mA - (Mercury MAR100-C) CHOKE

This shifts the load line toward higher voltage, so in theory: more output power and tighter low end, but higher current draw and stress on tubes.

Has anyone run a similar setup?
Did it actually translate into noticeable gains (headroom, punch), and was it worth the trade-offs?

Any practical concerns (screen dissipation, PT current, heat, reliability) I should watch out for?

Would appreciate concise, experience-based feedback.

 

[Exo-metal]

MGL is doing this. Is he the only one, no.

 

[glpg80]

Its possible to shake basement concrete slabs with original stock Marshall iron. You don’t necessarily need that high of a B+. Im not saying it doesn’t help but it certainly isn’t necessary.

The downside is that you’ll be wasting a lot of power in heat, and what you don’t waste in heat, you’ll be degrading tube life substantially to try to get greater levels of gain. You’ll also have to be mindful of wall voltages much more closely - I recommend running a voltage regulator.

 

[StanHavars]

MGL is doing this. Is he the only one, no.

MGL?

 

[StanHavars]

Its possible to shake basement concrete slabs with original stock Marshall iron. You don’t necessarily need that high of a B+. Im not saying it doesn’t help but it certainly isn’t necessary.

The downside is that you’ll be wasting a lot of power in heat, and what you don’t waste in heat, you’ll be degrading tube life substantially to try to get greater levels of gain. You’ll also have to be mindful of wall voltages much more closely - I recommend running a voltage regulator.

I really wonder what will be the real life difference, between those and the stock, is it really worthy?

A lot of people swear to the sound of the late 60’s Marshalls which are running pretty high plate voltages, so this should be to some extent a part of it wright?

 

[glpg80]

I really wonder what will be the real life difference, between those and the stock, is it really worthy?

A lot of people swear to the sound of the late 60’s Marshalls which are running pretty high plate voltages, so this should be to some extent a part of it wright?

IMO amps that have that high of a B+ tend to have a bell like underlying tone to them. That crystal clear attitude from running the power side in near ultra linear mode even with reduced screen voltages. Personally it’s nothing I chase for ultra high gain design but sounds great for that chainsaw reduced gain type of sound that’s extremely responsive as found in hiwatt inspired designs.

You have to be a bit more mindful about what you’re doing with power amp and preamp design for high gain but it does have a distinct sound that’s you either can’t get enough of or don’t like at all. Those that want it sell everything else that no longer compares.

 

[Jakem]