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 RectifiedAmps »

Mike Clayton wrote:That's the one, thanks. I prefer bias wiggle trem like on Princeton, do you know why they went to the optocoupler?
I can’t say for certain, but it might’ve been that the optocoupler design was the best way (they could think of) to have tremolo on only one of two channels. It’s also more consistent in its effect, whereas the strength of bias-wiggle trem can vary with the bias point and age of the output valves. From a design perspective, messing with bias is not a good idea since it does put extra strain on the output valves. I’ve seen a few Holden amps that’ll start to redplate if you crank the tremolo intensity, for example.

This is all supposition though- most people would just say Leo made all his decisions based on miniscule cost savings!

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Re: Whats on your amp workbench?

Post by MikeC »

RectifiedAmps wrote:
Mike Clayton wrote:That's the one, thanks. I prefer bias wiggle trem like on Princeton, do you know why they went to the optocoupler?
I can’t say for certain, but it might’ve been that the optocoupler design was the best way (they could think of) to have tremolo on only one of two channels. It’s also more consistent in its effect, whereas the strength of bias-wiggle trem can vary with the bias point and age of the output valves. From a design perspective, messing with bias is not a good idea since it does put extra strain on the output valves. I’ve seen a few Holden amps that’ll start to redplate if you crank the tremolo intensity, for example.

This is all supposition though- most people would just say Leo made all his decisions based on miniscule cost savings!
I think your last sentence is the most likely reason!!

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Re: Whats on your amp workbench?

Post by Cdog »

Mike Clayton wrote:
Cdog wrote:I put a cap across my roach too.... Used a 27n as that's what I had at the time. It smooths the waveform a little, but still sounds good.
Interesting, that's twice+ the value of the recommended cap (.01 uF). It must be effecting the neon's pulsing waveform - did you see the tremolo waveform change on an oscilloscope?
Used my earometer for that one :lol:

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Re: Whats on your amp workbench?

Post by MikeC »

I don't trust my earometers - maybe they need calibrating!

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Re: Whats on your amp workbench?

Post by MikeC »

Feeling pretty satisfied because I've just completed the '64 Vibroverb amp chassis that I've been building for the last 5 weeks :D The .01uF cap across the roach's neon to ground fixed the tremolo ticking. She's all biased up (at just under 70% max plate dissipation which is 21 Watts for my TAD 6L6GC's) and sounding lush thru my open back 112 wideboy cab loaded with an Eminence Legend 1258. Just waiting on the pine combo cab to be finished (BG 'da man) and I've already purchased a re-coned 15" JBL K130 from an NZG member just for this project. I won't sound like SRV but I know one guy that will! And for those amp guts voyeurs, here's a couple of pics of the finished product.
Finished Chassis Topside.jpg
Finished Chassis Topside.jpg (154.69 KiB) Viewed 3395 times
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Re: Whats on your amp workbench?

Post by Bg »

Oh thats looking bloody good! Give it to me and I'll cab it ;)
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Re: Whats on your amp workbench?

Post by MikeC »

"Bring me an amp I'm the cab'net man..." :mrgreen:

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Re: Whats on your amp workbench?

Post by yoggo »

My Blackstar ID core’s power supply has died, so I’m thinking about turning it into a powered cab - has anyone had any luck with the little cheap Class D modules, based on TPA3116 or similar IC’s?

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Re: Whats on your amp workbench?

Post by Bg »

A couple of refinish shots... this is a cracker!

This is my second go, the 'marshall' tolex just didn't stick properly. This is why I'm doing a 7 day drying thing now.

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Re: Whats on your amp workbench?

Post by Bg »

Heres some shots of my weekend of work, both cabs are about finished!

Nice bit of pine and some lovely tight dovetails :D

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back panels to make....

And a marshall style 2x12 :)

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Literally need to install the jack socket and feet :)
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Re: Whats on your amp workbench?

Post by Cdog »

Dang!😎
Looking great... 2 cabs in a weekend is approaching Marshmallow-levels of productivity, just sayin

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Re: Whats on your amp workbench?

Post by Bg »

Nah the marshall was on the go for a few weeks, its been a slow burner as I don't like working with plywood lol.
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Re: Whats on your amp workbench?

Post by Candeevr4 »

Much excite on this end! :D

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Re: Whats on your amp workbench?

Post by Jay »

Early amp and cab built by MikeC and BG... They have come a long way, haven't they :lol:

https://www.bidbud.co.nz/3084229914
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Re: Whats on your amp workbench?

Post by Bg »

Jay wrote: Fri May 07, 2021 10:42 am Early amp and cab built by MikeC and BG... They have come a long way, haven't they :lol:

https://www.bidbud.co.nz/3084229914
And...... predictably....... banned.
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