70/71 Spec 1987.

Get support and show off your MetroAmp 50 Watt kit builds.

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revolver1
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70/71 Spec 1987.

Post by revolver1 » Tue Nov 07, 2017 10:23 am

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So I've made a start on the next one.

I wanted the cans on top and after info gained through the usual suspects soon realised I would be building more of a 70/71 spec rather than a 69.

(Again a big thanks to everyone for all the knowledge).

So filtering wise I've opted for 50/50uf mains, 50uf screens, 50uf phase inverter and 32/32uf pre amp.
Last edited by revolver1 on Tue Nov 07, 2017 11:02 am, edited 1 time in total.

revolver1
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Re: 70/71 Spec 1987.

Post by revolver1 » Tue Nov 07, 2017 10:25 am

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I cut the pre-amp filter hole out with a 32mm hole saw. I later found you can get the hole saws in 1mm increments and so a slightly smaller hole would have been more appropriate.

It worked out alright though, I then protected the cut steel with a dab of galvafroid paint.

The face plates are from Valve storm. I sent them off to Modulus amplification in Scotland (UK) to have the JMP logo put on the front and the blurb on the back.

The back blurb was supposed to be stacked as in 3 separate lines. Not sure why but it didn't work out that way.

I think Michael did a great job, it looks pretty good anyway.
Last edited by revolver1 on Tue Nov 07, 2017 12:42 pm, edited 4 times in total.

revolver1
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Re: 70/71 Spec 1987.

Post by revolver1 » Tue Nov 07, 2017 10:27 am

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So again here is about as far as I can go with out the iron.

Good news the iron should be here in the next couple of weeks.
Last edited by revolver1 on Tue Nov 07, 2017 11:19 am, edited 1 time in total.

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Re: 70/71 Spec 1987.

Post by revolver1 » Tue Nov 07, 2017 10:28 am

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I made the board from Carp brand Tuffnol, I'm quite happy with the way it's turned out.

Big thanks to neikeel for the tip off on the snubbers. 8)
Last edited by revolver1 on Tue Nov 07, 2017 11:34 am, edited 1 time in total.

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Re: 70/71 Spec 1987.

Post by revolver1 » Tue Nov 07, 2017 10:29 am

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So after much thought and looking at the info and pics on the excellent Marstran site and amp archives I opted for the .68uf/820R combo.

I only have experience with a 69 100watt.
With the last one I went with 2.7k but with a 4700pf brghtcap.

I really liked the way that turned out so for this one I want to go with a 5000pf dog bone bright cap. I'm trying to second guess things a little here but maybe the 820R will get me in the zone.

Either way it'll make it a little different from the rest..... 8)
Last edited by revolver1 on Tue Nov 07, 2017 12:48 pm, edited 5 times in total.

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Re: 70/71 Spec 1987.

Post by revolver1 » Tue Nov 07, 2017 10:30 am

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Re: 70/71 Spec 1987.

Post by revolver1 » Tue Nov 07, 2017 10:32 am

Image

So here's a sneak preview before the iron goes in.

Gotta say a big thanks to neikeel for the help with the diodes and snubbers.

It has definitely been more of a challenge getting the info on the 50watt.

And so I wait.....

Oh, I've got the head shell coming from John Wheeler at Stone Age Custom Cabs. He has been showing me pics as they are being made and they look amazing. I'll be sure to post some pics when they turn up. Shouldn't be too long now.

I was going to do a Superbass next but I think I'm going to redo the board so I guess it's going to be the Superlead next.

There's a couple of points I need to 're address on the 2203 and this build and then I guess I'll see you all over in the 100watt section. Of course I'll be back to Finnish this one when the iron showes up. :thumbsup:

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neikeel
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Re: 70/71 Spec 1987.

Post by neikeel » Tue Nov 07, 2017 1:50 pm

Huge pics but very nice neat work.

Top notch so far :worthy:
Neil

danman
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Re: 70/71 Spec 1987.

Post by danman » Tue Nov 07, 2017 8:13 pm

Looking great so far!!

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bill bokey
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Re: 70/71 Spec 1987.

Post by bill bokey » Thu Nov 09, 2017 2:28 am

Looking great ! Nice work ! :thumbsup:

NoMasterVol
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Re: 70/71 Spec 1987.

Post by NoMasterVol » Sun Nov 19, 2017 11:48 pm

cant see photos :cry:

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Re: 70/71 Spec 1987.

Post by RockinRocket » Mon Nov 20, 2017 7:28 pm

Looking good !

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