Whats on your amp workbench?

Amp tinkerers and people who aren't afraid of 700 volts or so in here....

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Re: Whats on your amp workbench?

Post by Repair_Rob »

RectifiedAmps wrote: Sun May 22, 2022 8:52 pm This is a new one for me. Customer dropped off a ‘Norseman’ 10W amp - made right here in Wellington back in who-knows-when. Anyone come across one before?
https://vikingsevenseas.co.nz/pages/about-us
...Then the company moved to the top floor of 13 Jessie Street. One room was an office, the second was a record store, and the third held an assembly line where Ron Dalton made amplifiers and radio tuners....

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Re: Whats on your amp workbench?

Post by MikeC »

Moneyshot - robthemac's DR I build I recently completed. Here's what it looks like Rob!
Robthemac's Completed DR Chassis.jpg
Robthemac's Completed DR Chassis.jpg (1.65 MiB) Viewed 546 times
The Normal channel has reverb, the robrob "lead channel mod" (which gives it a more Marshall voicing suiting pedals) and is in phase with the Vibrato channel.

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Re: Whats on your amp workbench?

Post by Bg »

Looking tasty as per :)
So, is that low alcohol or no alcohol at all? mmmm, no alcohol, do you want to try it? Noooooooooo.

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Re: Whats on your amp workbench?

Post by codedog »

MikeC wrote: Sun Jun 05, 2022 4:12 pm Moneyshot - robthemac's DR I build I recently completed. Here's what it looks like Rob!
Robthemac's Completed DR Chassis.jpg
The Normal channel has reverb, the robrob "lead channel mod" (which gives it a more Marshall voicing suiting pedals) and is in phase with the Vibrato channel.
Does the Normal channel also have Vibrato?

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Re: Whats on your amp workbench?

Post by MikeC »

codedog wrote: Sun Jun 05, 2022 4:46 pm
MikeC wrote: Sun Jun 05, 2022 4:12 pm Moneyshot - robthemac's DR I build I recently completed. Here's what it looks like Rob!
Robthemac's Completed DR Chassis.jpg
The Normal channel has reverb, the robrob "lead channel mod" (which gives it a more Marshall voicing suiting pedals) and is in phase with the Vibrato channel.
Does the Normal channel also have Vibrato?
Yep!

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Re: Whats on your amp workbench?

Post by codedog »

MikeC wrote: Sun Jun 05, 2022 4:54 pm
codedog wrote: Sun Jun 05, 2022 4:46 pm
MikeC wrote: Sun Jun 05, 2022 4:12 pm Moneyshot - robthemac's DR I build I recently completed. Here's what it looks like Rob!
Robthemac's Completed DR Chassis.jpg
The Normal channel has reverb, the robrob "lead channel mod" (which gives it a more Marshall voicing suiting pedals) and is in phase with the Vibrato channel.
Does the Normal channel also have Vibrato?
Yep!
So the Normal channel is Marshall-esque voiced, and the Vibrato channel is "normal" Fender voiced?

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Re: Whats on your amp workbench?

Post by MikeC »

codedog wrote: Sun Jun 05, 2022 5:01 pm
MikeC wrote: Sun Jun 05, 2022 4:54 pm
codedog wrote: Sun Jun 05, 2022 4:46 pm

Does the Normal channel also have Vibrato?
Yep!
So the Normal channel is Marshall-esque voiced, and the Vibrato channel is "normal" Fender voiced?
Yep again. The Normal channel is Marshall-esque voiced and has reverb, tremolo and is in phase with the Vibrato channel.
So channels can be jumpered (I do it with a pedal).
And the Vibrato channel is exactly as Leo designed it on the AB763 circuit :)

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Re: Whats on your amp workbench?

Post by codedog »

MikeC wrote: Sun Jun 05, 2022 5:10 pm
codedog wrote: Sun Jun 05, 2022 5:01 pm
MikeC wrote: Sun Jun 05, 2022 4:54 pm

Yep!
So the Normal channel is Marshall-esque voiced, and the Vibrato channel is "normal" Fender voiced?
Yep again. The Normal channel is Marshall-esque voiced and has reverb, tremolo and is in phase with the Vibrato channel.
So channels can be jumpered (I do it with a pedal).
And the Vibrato channel is exactly as Leo designed it on the AB763 circuit :)
Wow, this is very intriguing! I wonder how the Normal Marshall-esque channel sounds lightly driven or on the edge of breakup!

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Re: Whats on your amp workbench?

Post by robthemac »

Looks choice, Mike.

Glad I went for those mods. Should make it pretty versatile.

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Re: Whats on your amp workbench?

Post by codedog »

robthemac wrote: Sun Jun 05, 2022 5:31 pm Looks choice, Mike.

Glad I went for those mods. Should make it pretty versatile.
Would you be up for recording a demo? :wink:

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Re: Whats on your amp workbench?

Post by robthemac »

codedog wrote: Sun Jun 05, 2022 5:36 pm
robthemac wrote: Sun Jun 05, 2022 5:31 pm Looks choice, Mike.

Glad I went for those mods. Should make it pretty versatile.
Would you be up for recording a demo? :wink:
Yeah happy to. Picking it up on the weekend of the 18th. Don't have mics myself, but if you're in Auckland we could wind it up somewhere.

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Re: Whats on your amp workbench?

Post by codedog »

robthemac wrote: Sun Jun 05, 2022 5:37 pm
codedog wrote: Sun Jun 05, 2022 5:36 pm
robthemac wrote: Sun Jun 05, 2022 5:31 pm Looks choice, Mike.

Glad I went for those mods. Should make it pretty versatile.
Would you be up for recording a demo? :wink:
Yeah happy to. Picking it up on the weekend of the 18th. Don't have mics myself, but if you're in Auckland we could wind it up somewhere.
Ach... double bugger... you don't have a mic, and I'm not in Auckland!

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Re: Whats on your amp workbench?

Post by MikeC »

codedog wrote: Sun Jun 05, 2022 5:22 pm
MikeC wrote: Sun Jun 05, 2022 5:10 pm
codedog wrote: Sun Jun 05, 2022 5:01 pm

So the Normal channel is Marshall-esque voiced, and the Vibrato channel is "normal" Fender voiced?
Yep again. The Normal channel is Marshall-esque voiced and has reverb, tremolo and is in phase with the Vibrato channel.
So channels can be jumpered (I do it with a pedal).
And the Vibrato channel is exactly as Leo designed it on the AB763 circuit :)
Wow, this is very intriguing! I wonder how the Normal Marshall-esque channel sounds lightly driven or on the edge of breakup!
Robbie will able to tell you soon! I can't crank it at home here. Rob Robinette describes the mod as follows:-

Voice a "Lead" Channel

This is another one of my favorite mods. In a typical two channel amp it's possible to voice one of the channels with a more modern, tight, Marshall "Lead" style tone. Remember, the only difference between most Normal and Bright channels is a bright cap on the bright volume pot which bypasses high freqs around the volume pot at low volume levels. At max volume there is no difference between the Normal and Bright channels so voicing one channel differently is a useful mod.

This mod will tighten up the overdrive tone and bottom end and make your amp more pedal friendly. Modifying only the first gain stage removes some of the guitar's low frequencies so the clean tone will be thinner but during overdrive later gain stages with larger coupling caps will allow low frequency intermodulation distortion harmonics to be passed through the amp for a subtle but thick low end. This will not happen in an amp with small coupling caps throughout. This "Lead" Channel mod will blow away your Marshall buddies.

You will also gain some clean headroom and maximum volume because low frequencies use up a lot of the amps power so removing very low frequencies allows more amplification of the remaining audio frequencies.

When evaluating this mod be sure and try a boost pedal to get the gain and distortion up--this is when this mod really shines. I used the Marshall 1987 Plexi as my roadmap for this "Lead" channel mod. The Plexi uses preamp component values to reduce low frequencies and boost high frequencies to offer a clean, tight, modern overdrive tone. The Lead channel will also be more pedal friendly than a normal Fender channel.

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Re: Whats on your amp workbench?

Post by robthemac »

This mod may make my 1974x kit somewhat redundant... We'll see!

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Re: Whats on your amp workbench?

Post by PaulWD »

Forgive me for not-guitar content. I collected this Jennings Univox j6 yesterday (along with a bunch of projector amps). Interesting sounding things - del Shannon run away solo and icky thump to name a couple of examples. Also Telstar by the tornadoes.

Keyboard is simply a chain of resistors, and needs a little woodworking.

I'm going through and changing electro caps and drifty resistors in the first instance.

Year of construction is 1955
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