Another Small Special build with a twist

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Synchu
Posts: 522
Joined: Sun Mar 11, 2012 5:24 am

Another Small Special build with a twist

Post by Synchu »

Branching out from the excellent Small Special thread of Jelle here is my build.
Although I built quite a few stomp boxes, this is only my second amp build after a 5E3 kit (which is one of my favorite amps now, btw), so bear with me, I am still trying to make it in baby steps :)
A little bit of the story - some many moons ago I was rigging around a Super Reverb build to follow the 5E3 above, when I stumbled upon the above mentioned thread and started to research information.
What I found out is the posted schematic of Small Special and that Morgan SW series is basically a Small Special with few values (cleverly) changed and some switches omitted (namely Guitar/Mic and Accent switch). Since there was a (blurry) picture of SW22 guts on tgp, that looked a tad simpler than the exemplary build in Jelle's thread, I decided to draw the layout based on to SW (being hesitant in my skills to handle something that looked more complicated). I wasn't quite right is sufficient to say.
Fast forward some months, I read tons of info here, few books on tube (and valve :) ) amps design and building, learned that designing, drilling and painting amp chassis is not quite the same as with the stomp boxes and same is valid for designing a turret board.
I gathered slowly the components and got hit with shipping forgetting few rather important things.
As the component choices go, here at my place and generally in EU it isn't that easy to get hold on a lot of stuff.
I had some stash of carbon comp resistors left from some "mojo"style tag board stomp builds, so I used them where I had the appropriate values. Other resistors used are pretty much standard stuff available. F&T electrolytics, Jupiter and CD silver mica capacitors had been used and transformers are Super Reverb set from TRM audio.
I used PTFE board, as I ordered some of the parts from Barry @ampmaker in UK and he had that praised. And it is indeed very easy to work with. Stranded wire throughout and some PTFE stranded wire(PS connections and heaters). Doesn't look that clean (some of that due to my skills, I guess ;)), but seemed to me more foolproof.
I called the amp Sleeping child, since it has been almost entirely build while the kids were sleeping and it has very nice and tender voicing:)
I think that's all. Headshell is still in progress and as the time allows will post an update.
I am already after the possible mods. Mid pot hole has been drilled and pot installed, but not wired, since I wanted to hear the circuit as it is. I am thinking of adding post PI CF or reverb (that's a big chassis with a lot of space and 2 x 12AX7 just look insufficient:) ) and a Cut control (similar to Contour in TR designs). Will have to do some more calculations, based on the actual build measurements to find if any gains from the post PI CF and any input is appreciated on that.
Bear with me on the samples - late night, first takes everything with some basic drum track used barely to keep the rhythm (it does well, me not so).
I described what was used in the soundcloud comments.

I am very happy with how it turned out and it has been a great learning experience for me.

Larger sized photos link: http://www.flickr.com/photos/synchu/set ... 510484205/
[img:320:211]http://farm3.staticflickr.com/2844/1025 ... efb8_n.jpg[/img] [img:320:239]http://farm9.staticflickr.com/8122/1025 ... e060_n.jpg[/img] [img:320:239]http://farm6.staticflickr.com/5469/1024 ... 61e0_n.jpg[/img]
[img:239:320]http://farm4.staticflickr.com/3799/1024 ... d223_n.jpg[/img][img:320:239]http://farm3.staticflickr.com/2886/1024 ... 5a90_n.jpg[/img]


Ampgarage pictures:
[img:500:374]http://farm6.staticflickr.com/5500/1033 ... 736902.jpg[/img] [img:500:374]http://farm3.staticflickr.com/2814/1033 ... 65fe8d.jpg[/img]

Samples:
Clean Strat - http://soundcloud.com/synchu/synchussleepingchild-clean
With Baja Real Tube Overdrive - Strat again http://soundcloud.com/synchu/synchussle ... ild-2-with
Cranked with Gibson LP
http://soundcloud.com/synchu/synchussleepingchild-3
Last edited by Synchu on Fri Oct 18, 2013 5:45 am, edited 1 time in total.
telentubes
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Re: Another Small Special build with a twist

Post by telentubes »

Off to work. I'll have another look this eve. Good so far, though we might like some more detail and better lit photos. The "art shots" are nice, but you can't really tell what's in there. I loved the tone at first listen.
Synchu
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Re: Another Small Special build with a twist

Post by Synchu »

Good point. Will try shooting something more appropriate tonight.
It is hard to resist what all this phone apps suggest :)
dcribbs1412
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Re: Another Small Special build with a twist

Post by dcribbs1412 »

Congrats Synchu
nice build... Clean strat clips sounds great. Other clips not working.
With all the time and work you have in this build,
I would be tempted to leave this "sleeping build" as is and build another
with the mods and skills you have learned.
Again nice build...thanks for sharing

Darin
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M Fowler
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Re: Another Small Special build with a twist

Post by M Fowler »

Sounds great on all three clips.

Bring a strat and a LP to the gig and you can cover many songs.
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Blackburn
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Re: Another Small Special build with a twist

Post by Blackburn »

Great clips. Really dig that last one with the LP. Great looking build too. :)

I want to do one of these.
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M Fowler
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Re: Another Small Special build with a twist

Post by M Fowler »

I found the easiest way to get that Dumble honk tone from an amp is to use slight delay I use Boss DD3 and I use a Boss Blues Driver.

My Zendrive works well too but I prefer the slight boost the Blues Driver gives and use a Les Paul guitar.

But that was a good clip I agree.
stevlech
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Re: Another Small Special build with a twist

Post by stevlech »

Thank you for the clips. I'm pleasantly surprised at the cranked tone. The clean strat sound is excellent as well.
Synchu
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Re: Another Small Special build with a twist

Post by Synchu »

Thank you all for the good words.
I've added couple of pictures above (the flickr link can be used to view larger sized ones).

To be honest, I was pretty surprised at the cranked tone as well. Thought it will be clean amp :)
I tried a bunch of pedals in front of it and so far couple of favourites - this Germanium booster that the recording with LP was done with. It doesn't provide a huge boost, but colors the tone nicely, the Baja real tube overdrive (running on 15 VAC PS, but tube glows and sounds nice though;) ). Close runner is a G2D Creamtone based pedal with few tweaks. This one is in the realm of the Blues Driver I would say.

Btw, got to jam on a track provided by a forum mate it is the LP again http://soundcloud.com/synchu/jamtrack-m-ss_glp_d . I am truly enjoying what gets out of this amp :)

As for the mods - I will probably test few of the planned ones and get my head over what will stay or be moved away.

Thanks again. Now gotta decide what's next in the list - SSS, Trainwreck, JTM45 or a Bassman, tough choices...
Niki
telentubes
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Re: Another Small Special build with a twist

Post by telentubes »

Synchu. I'd be interested in the "draft layout" you mentioned in the thread that Jelle started about his SS, and any mods you may have come up with. Maybe others would be as well.

I thought the tone in the 1st and 3rd cuts were great (liked the tunes as well) The middle track with the Strat, not so much.

I'm looking for a new project to replace the 5B6 I built (tons of hours tweaking and rebuilding) but will end up scrapping. I've been eying the SS for a while and judging by your results, this may be a good choice.
Synchu
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Re: Another Small Special build with a twist

Post by Synchu »

Thanks telentubes.
Glad you liked the tones.
Now, the layout is based on a tgp picture of SW22 guts found here. Seemed simpler to me at first sight.
As for the mods, these weren't quite significant - deep switch - pretty much wired as other ODS type amps - 270K resistors to pots and 0.01 cap and 1M on the switch. Then I opted for a 0.05 bass cap. Guitar/Mic switch was omitted.
Bright switch cap is 250pF. There's no Accent switch. It is an already dark amp and I prefer having the cap on the LNFB wired permanently.
2.2uF cap wired after the NFB resistor (which is 100 Ohm - yes that's low and I read concerns in Jelle thread, but to me it sounds good). I am going to test 1uF one at the LNFB and wire a mid pot as well for now. Still pondering around the PI CF idea as done by ToneMerc and mentioned in the other thread.
Bear with me on the layout - that's my first one - have to practice my skills there.

EDIT: See updated layout on page 2.
Last edited by Synchu on Tue Oct 22, 2013 8:45 pm, edited 1 time in total.
telentubes
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Re: Another Small Special build with a twist

Post by telentubes »

Thanks for that. I think I will have a go at this one.
TNT
EaNot
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Re: Another Small Special build with a twist

Post by EaNot »

Jumper (blue line) under board?
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Synchu
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Re: Another Small Special build with a twist

Post by Synchu »

Good point EaNot!

Now - the layout is (I hope) exactly as I built the amp.

What I thought when drawing it and looking at the above mentioned photo at tgp is that it will probably make some sort of ground loop (I am not sure whether I am correct in this statement, though :)) wired this way (i.e. with the jumper), although that's what the schematic calls for (and usual NFB design).

So I tested and it is indeed adding a huge amount of low freq rumble coming through the speakers and sounds like a ground loop happening.

Current wiring doesn't make a lot of sense to me as well. What I planned to do this week apart from few other mods that I am waiting the parts for, is to rewire this section to what will seem to me as a proper NFB loop.

Other comments on that will be much appreciated :)
EaNot
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Re: Another Small Special build with a twist

Post by EaNot »

Have you tried disconnect "global NFB circuit", eg from output jack? Since in this case the 100 ohms-1(2)uF circuit - it's just a ballast, not a global negative feedback. Bear with me for my english :).
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