What's My Name?

[nickb]

Something completely different came my way. I think this is something very few will have seen. I haven't got a full set of pics yet, but I'll add when I have it back together. I know the name of the manufacturer but not the model. I've hidden the name for now just so you can have fun making a guess or two. 2 EL34 2, 2x ECC83.

I had started to dismantle it before I took any pics so these will have to do for now. This is the most original guitar amp Ive ever worked on in several ways.

First this is top top with the cover off. You can see the sides are two aluminum extrusions and the chassis drops in from the top, tubes first.


Here I've taken it apart some more. Complete disassembly was necessitated by the silicone adhesive which held it all together. I could not get the glued-in chassis out without doing this.



Here is the chassis top. Note the smoke marks around the EL34 socket over where the PCB had arced. You can just about see the side of the front panel with cooker style knobs. I swear when it's all together it looks more like a portable heater than a guitar amp.



and the fried PCB


All the controls use switches instead of pots so I just had to reverse engineer the schematic for curiosity and prosperity.



Clearer schematic pdf:
Schematic.pdf

Much to discuss on this design both mechanical and circuit wise...later.

So have you guessed the name and manufacturer yet?

[Jazz P Bass]

I don't know.
It says Sonus Engineering, Scotland on the rear cover.

Only info that I could find:
http://www.chambonino.com/work/miscguitar/misc7.html
http://www.ccmusicshop.co.uk/product...-guitar-combo/
http://www.wildhorseguitars.com.au/s...us---SC30.aspx

[nosaj]

Something completely different came my way. I think this is something very few will have seen. I haven't got a full set of pics yet, but I'll add when I have it back together. I know the name of the manufacturer but not the model. I've hidden the name for now just so you can have fun making a guess or two. 2 EL34 2, 2x ECC83.

I had started to dismantle it before I took any pics so these will have to do for now. This is the most original guitar amp Ive ever worked on in several ways.

First this is top top with the cover off. You can see the sides are two aluminum extrusions and the chassis drops in from the top, tubes first.
[ATTACH=CONFIG]54775[/ATTACH]

Here I've taken it apart some more. Complete disassembly was necessitated by the silicone adhesive which held it all together. I could not get the glued-in chassis out without doing this.

[ATTACH=CONFIG]54776[/ATTACH]

Here is the chassis top. Note the smoke marks around the EL34 socket over where the PCB had arced. You can just about see the side of the front panel with cooker style knobs. I swear when it's all together it look more like a portable heater than a guitar amp.

[ATTACH=CONFIG]54777[/ATTACH]

and the fried PCB
[ATTACH=CONFIG]54778[/ATTACH]

All the controls use switches instead of pots so I just had to reverse engineer the schematic for curiosity and prosperity.

[ATTACH=CONFIG]54779[/ATTACH]
Much to discuss on this design both mechanical and circuit wise...later.

So have you guessed the name and manufacturer yet?

You gave it away with the pcb and speaker logo . Sonus not sure on model. Here's one.

nosaj
http://www.ccmusicshop.co.uk/product...-guitar-combo/

[nickb]

I don't know.
It says Sonus Engineering, Scotland on the rear cover.

Only info that I could find:
http://www.chambonino.com/work/miscguitar/misc7.html
http://www.ccmusicshop.co.uk/product...-guitar-combo/
http://www.wildhorseguitars.com.au/s...us---SC30.aspx

Dang - I missed that I thought I had obscured all the names in the interest of fun.

[nickb]

You gave it away with the pcb and speaker logo . Sonus not sure on model. Here's one.

nosaj
http://www.ccmusicshop.co.uk/product...-guitar-combo/

I guess I missed that branding. Never mind. The one you linked is different but this is still a 50W combo. On checking I see simply upload the wrong photos.

They clearly went to some trouble to come up with something different. Of course the trouble with not using tried and tested is the risk of going horribly wrong.

I'm sure the extrusions don't come cheap. But then it's all glued together as though they ran out of neat ideas to do it. Other odd stuff was there is an aluminum screening plate behind the front panel control PCB with almost no clearance from the board. To mitigate the chance of a short a piece of not quite big enough heavy paper had been placed between the screen and the board. When I put it back together I elongated the screen mounting holes so I could move it away from the PCB. The main filter caps were so close to the power connector that he clip would not close. Getting the main PCB out was a tricky juggling act, bordering on impossible.

But it's easy to be critical and hard to get everything right and I have to commend them for striking their own course. A wiser man than me said you have to walk a mile in another man's shoes....

I wonder whether they were running out of cash and had to start shipping as many a possible to try to salvage the cash flow and so didn't have the opportunity to iron out the kinks.

[nosaj]

Dang - I missed that I thought I had obscured all the names in the interest of fun.

I guess we're just no fun at all.

nosaj

[Jazz P Bass]

And they even included there contact info:



Looks like a cool amp.

I like all of the rotary controls.

[J M Fahey]

Wow!!!
I guess weird and kinky are just understatements

Besides cosmetic choices and even the full switched everything approach, to each his own, I find *one* flawed concept , probably only one of three partners had Electronics formation and that from the SS field, no clue on specific Tubes or Guitar needs.

So Designer was worried about *shorts* (which are not a big deal in Tubeland) and added a specific protection which works similar to a Fuse in series with speaker which disconnects amp from load in case of short.

Fine in Siliconworld, not so much in Glassworld, and will cause arcing in OT, power tube sockets or both, so check whether you find some of that

Oh, ... I SEE

Leave everything else as-is to keep uniqueness but please remove that "protection/destruction" network at the output; connect amp straight to output jack or even better, use the shorted jack Fender trick.
Much safer.

Double premium for the "resonance chambers" , again NOT from Guitarworld but, maybe, Hi Fi world.

FWIW resonance chambers are useless in an open cabinet.

Wait for the Movie: "Three No Clues join to make Guitar Amps"

NO points for gluing everything together

As of:

Extra points for the loooooong stitch joining a leatherette "skirt" to main wrapping to take care of the controls cutout on top panel and the piano hinge allowing for the backside flip-up door.

[nickb]

The polyfuse was one of the things I was going to mention. On reflection I don't think the concern is warrantied for a couple of reasons. First, it's a 7.5A trip current device i.e. 450W into 8 ohms so i can't ever see it operating. Secondly, even if it did, the holding current is 3.75A (112.5W) and is resistance is still quite low. Even if it went open then there would still have 470 ohms, which while not great, helps greatly to mitigate high voltage breakdown concerns.

Anyone looked at the unusual tone controls yet?

[nickb]

I got quite a bit more info on this from the owner. Interesting but still no name. The following is edited from the owner, any opinions expressed are just that.

"Tam Lynch was the guy that made these, around late '99 and 2003. They were originally very expensive, around the 3k+ area (the 2x12" version was at least), and came in blue and green badge versions, rated at 50 and 30 watts respectively. Tam wired each one himself in a warehouse next to a petrol station behind Maryhill in Glasgow, and of the original amps, a few are scattered across the globe. It also had a matching 1x15" cab which clipped underneath and was exceedingly loud. I've got a 2x12" version as well, as I love the way they sound - Tam's idea of overdrive went as far as gentle breakup, so these were designed to run ultra-clean. I once had another that had a drive channel as well that was hopeless, as these drive brilliantly with pedals but poorly on their own - there just isn't enough gain in the conventional sense. The last I heard of Tam he'd been a consultant for Carlsbro, but that was 20 years ago - Sonus was impossibly badly run, and the amps were hugely overpriced for the time."

[nickb]

More pics:

Getting the PCB in and out was very fiddly, one step away from impossible:


This is the front panel control PCB, temporary knobs for testing. I had to replace all the switches as contact cleaner didn't bring then back to life:


The lack of clearance between the front panel PCB and it's shield was a worry.



I elongated the holes in the shield so it could be moved away at little.

Note also a bit of thick card that lived under the main filter caps. I got rid of this and stuck some rubber "bump-on" feet to the bottom of the board as a neater solution.

Here's how it goes back together. I think the construction was both novel, rather clever and very quick to do. First the base screws onto the two side extrusions. The speaker baffle then slides into a groove from the top.



The rear cover goes in next.


The amp chassis drops into place with the front and back panels slotting into grooves on the extrusions.


The top and bottom are milled out of ABS and are very heavy. The top bolts on and we're done. I did silicone the sections to prevent vibration. I did not silicone the amp chassis as that is why I could not get it out to start with. I took the whole thing apart as I was convinced there was a couple of hidden bolts as it was so tight.





The construction, the tone control circuit and the speaker protection ( if it works ) all show original thinking. May you'll get some ideas.

[nickb]

Lastly, here are the tone control responses. Certainly quite unique:

BASS


MID


TREBLE


I came up with a cunning 12 position switch to make this an easy sim in SPICE.