Park Rock Head-ish build

Marshall Amp Discussion

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dvnator
Posts: 12
Joined: Sat Feb 28, 2009 5:47 am
Location: Las Vegas, NV

Park Rock Head-ish build

Post by dvnator » Sun Nov 12, 2017 5:06 pm

I’d thought I’d post my latest build here on the chance there might be some interest in a fairly obscure Marshall amp.

The amp based on/inspired by the Park Rock Head 1210/1240.
For those that don’t know Park amps were built and designed by Marshall but sold under the Park name due to distribution deal/business stuff.

The amp is definitely not a clone as I built it based on parts I had on hand and I did a fair amount of tweaking. Also, the original schematic is a little hard to make out in places.

I used an Antek AS - 2T300 for the PT and the OT is from an even more obscure amp called the Nomad. I didn’t notice any voltages on the original schematic but I’m guessing my amp is at least about 50v lower than the original.

The original Park had a footswitch to change how the guitar signal entered the amp so you could cascade the first two triodes or bypass the “bright” input. I went a different way and did a switch to bypass the second triode and alter the bias on the last triode for the clean “channel”.
My clean channel is very similar to the brilliant channel on the Marshall 2150. The OD sound is somewhere around the JCM800 zone I would say.

It’s built in a blackface chassis I got from Ted Weber years ago and mounted in an old cabinet I got at a thrift store.
It’s not a particularly good looking build, inside or out, but it it sounds pretty good IMHO.

This is the original schematic:

http://schematicheaven.net/newamps/park ... 0_rock.pdf

And this is my schematic:
Rockhead_Schem_v1.jpg
http://chasingtone.com/dvnator/wp-conte ... hem_v1.jpg

I did some clips. No pedals, just straight in a 2x12 with a Celestion 70th anniversary and a WGS Retro 30.
Playing is not great but you can get an idea of how it sounds.

Clean channel with a Telecaster



Gain channel (medium gain) with a Les Paul



Higher gain setting with a Les Paul

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Last edited by dvnator on Mon Nov 13, 2017 3:21 am, edited 1 time in total.

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xtian
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Re: Park Rock Head-ish build

Post by xtian » Sun Nov 12, 2017 6:56 pm

Nice work! Would love to see gut shots.
I build and repair tube amps. http://amps.monkeymatic.com

stephenl
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Joined: Wed Aug 13, 2008 10:21 pm
Location: Marlborough, MA

Re: Park Rock Head-ish build

Post by stephenl » Sun Nov 12, 2017 7:01 pm

Great sounding amp!
Steve

Vince
Posts: 50
Joined: Mon Jun 20, 2005 7:14 am

Re: Park Rock Head-ish build

Post by Vince » Mon Nov 13, 2017 6:52 pm

Hot amp! I like it!
I try to do 2-channel amp after you.
Elements in red circle will be matched to personal preferences.
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Last edited by Vince on Tue Nov 14, 2017 7:02 am, edited 1 time in total.

dvnator
Posts: 12
Joined: Sat Feb 28, 2009 5:47 am
Location: Las Vegas, NV

Re: Park Rock Head-ish build

Post by dvnator » Mon Nov 13, 2017 11:49 pm

That looks cool Vince. Nice way to split the volume controls.

Just a heads up, when you through the switch there is a bit of a pop when the bias shifts on that last triode. I've looked into ways of avoiding that (mosfet) but it seemed like more trouble than I was willing to do at the moment.

And here is a gut shot. Like most of my amps I built it on a universal turret board. I always do a lot of tweaking and the universal boards help with that. It kind of a tight squeeze and not quite a work of art but it gets the job done.
http://chasingtone.com/dvnator/wp-conte ... 153451.jpg

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