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Hoffman Amps Forum image Author Topic: Installing a Hiwatt Fixed Bias Inverter in a Marshall 2204ish amp  (Read 1976 times)

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Offline whalecalls

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Greetings,
    This is my first post here on this wonderful site. Quick question. Has anyone here ever tried building an amp with a Marshall-esque topology, but with a Hiwatt style PI? There are things that I love about Hiwatt and Marshalls and I'm wondering if it would be possible to get the best of both worlds. I love Hiwatt for the pure power that they have and for being an amazing pedal platform. They have a very "direct" sound and feel which I dig, however, they can be a bit sterile/neutral tonally. I know there's a lot of factors why hiatus have so much power (high plate voltage and those wonderful trannies), but I'm thinking a big part is that the PI doesn't distort a ton which makes it so great for pedals. I love my "Marshall", but I wish it had a bit more headroom to keep up with the DBS from my fuzzes and boosts like hiwatts do.
     Long story short.... Has any one put a Hiwatt PI in a Marshall 2204 style amp or has any built a dr504 with a predominately Marshall preamp? Thanks y'all.

Offline shooter

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Re: Installing a Hiwatt Fixed Bias Inverter in a Marshall 2204ish amp
« Reply #1 on: June 15, 2020, 06:28:30 pm »
welcome

I consider the pre "it's own thing", the PI and PA the "other thing", they stitch well regardless of brand, just your effort  :laugh:
Went Class C for efficiency

Offline whalecalls

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Re: Installing a Hiwatt Fixed Bias Inverter in a Marshall 2204ish amp
« Reply #2 on: June 17, 2020, 11:00:55 am »
Thanks Shooter,
     Yes, I'm sure it would work, but I wonder if changing the PI in a Marshall would dramatically alter its tone and/or give it some more headroom. I will try this out someday and posts. Thanks for the response! Cheers

Offline pdf64

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Re: Installing a Hiwatt Fixed Bias Inverter in a Marshall 2204ish amp
« Reply #3 on: June 17, 2020, 11:47:49 am »
I don’t see any big difference between the Hiwatt and Marshall LTPs? It’s not an apple and oranges thing. So no reason to expect a significant difference in performance.
Note that the Hiwatt isn’t fixed bias, it’s just a different arrangement of self bias. The difference is that the grid is referenced to a particular % of the HT, rather than the LTP’s tail.
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Offline whalecalls

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Re: Installing a Hiwatt Fixed Bias Inverter in a Marshall 2204ish amp
« Reply #4 on: June 19, 2020, 03:40:25 am »
PDF,
    Yeh, forgive me and my limited knowledge especially with PIs. Interesting about the grid differences. I will probably just experiment and see what happens. Thanks for the info!

 


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