SIII build from scratch

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AussieTim
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Re: SIII build from scratch

Post by AussieTim »

Hi Guys
Just wondering, I drilled the holes for some carling switches slightly too big.
Do any of you know where to get some nice shiny washers to go around them? I have been searching and cannot find anything I am probably looking in the wrong places, any suggestions?
Tim
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JMPGuitars
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Re: SIII build from scratch

Post by JMPGuitars »

AussieTim wrote:
Fri 05/13/22 6:07 am
Hi Guys
Just wondering, I drilled the holes for some carling switches slightly too big.
Do any of you know where to get some nice shiny washers to go around them? I have been searching and cannot find anything I am probably looking in the wrong places, any suggestions?
Tim
I use the 12.4mm ID washers meant for guitar pedals. You can get them from most pedal supply places, but I dunno what's easy to get down undah.
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Re: SIII build from scratch

Post by AussieTim »

Finally finished wiring this thing up, time to go through it with a fine tooth comb then follow the start up procedures, I know a guy who is a professional amp guy and is happy to help me commission it as has an oscilloscope and a lot of knowledge so I will see him in the next few days
Anyway here are some pictures of what I hope is the completed amp
PXL_20220612_055207702.jpg
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Re: SIII build from scratch

Post by AussieTim »

PXL_20220612_055257758.jpg
PXL_20220612_055251774.jpg
PXL_20220612_055246181.jpg
PXL_20220612_055238264.jpg
PXL_20220612_055227002.jpg
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geoff 1965
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Re: SIII build from scratch

Post by geoff 1965 »

Hello Tim,
As I mentioned before you need to swap those 6.3V supply’s around,the 1A supply goes to your ez81 and the 3A supply feeds the power and preamp tubes and you need to ground the centre tap of the 3Amp as well.
Good luck
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Re: SIII build from scratch

Post by JMPGuitars »

Geoff is correct. Don't power on the amp before making those changes.
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Re: SIII build from scratch

Post by AussieTim »

I think I must have misunderstood your original pickup about which output taps to use and where,
PXL_20220613_043851270.jpg
I believe I have it correct now
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AussieTim
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Re: SIII build from scratch

Post by AussieTim »

Well after a couple of years mucking around with this I have finally got it up and running.
I have done something right because it is dead quiet no whirring or buzzing
We had to correct a couple of problems, I mixed the channel inputs up onto v1 so the knobs were working on the wrong inputs which was a bit confusing for a couple of minutes
My friend who helped me with the start up was a concerned that the way the standby switch is configured so we will look at that
Now to complete the cabinet and the cosmetics
And experiment a bit with cap values etc and see if I like the way it is or something different
Tim
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Re: SIII build from scratch

Post by AussieTim »

Ok have had this thing running for a couple of months now and so far have found
1 switching valves doesn't seem to give a vastly different sound, probably not enough to worry about, I think I will remove the 6v6 valves and switch and just run with the el84s
2 Phil was right, it is pretty clean I will change some resistors and caps to make it into the Trinity Plexi 2 version
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Re: SIII build from scratch

Post by zaphod_phil »

AussieTim wrote:
Tue 09/06/22 5:58 am
Ok have had this thing running for a couple of months now and so far have found
1 switching valves doesn't seem to give a vastly different sound, probably not enough to worry about, I think I will remove the 6v6 valves and switch and just run with the el84s
2 Phil was right, it is pretty clean I will change some resistors and caps to make it into the Trinity Plexi 2 version
It is indeed very clean sounding in the online demo clip. but it's a very sweet silverFace--like clean 8)
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Re: SIII build from scratch

Post by Bieworm »

zaphod_phil wrote:
Wed 09/07/22 12:55 pm
AussieTim wrote:
Tue 09/06/22 5:58 am
Ok have had this thing running for a couple of months now and so far have found
1 switching valves doesn't seem to give a vastly different sound, probably not enough to worry about, I think I will remove the 6v6 valves and switch and just run with the el84s
2 Phil was right, it is pretty clean I will change some resistors and caps to make it into the Trinity Plexi 2 version
It is indeed very clean sounding in the online demo clip. but it's a very sweet silverFace--like clean 8)
Sweet silverface??? You do know most of those have reverb?? 🤣🤣🤣
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AussieTim
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Re: SIII build from scratch

Post by AussieTim »

Ok Ive been using this amp for six to eight months and Yes I am going to turn it into the plexi version, but at the moment I am attempting to build a cabinet for it using the plans that Modulus had on their website ( they seem to have disappeared with their web upgrade hopefully they will re-include their plans again, it was a great resource, luckily I had saved the 18 watt drawings)
Anyway I digress, what I would like is if any of you guys can steer me towards any information on cabinet building Tolexing etc. I would very much appreciate it.
I have trawled through this site I'm missing it.
Thanks
Tim
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Re: SIII build from scratch

Post by AleS »

Enjoyed reading through the posts and history of this (and was of course glad to see you came back to the project after the hiatus which I hope is now truly behind).

How are you finding the clean and breakup tones of the SIII? I'm currently scouting for a cleaner version of the design for a non-rock'n'roll machine amp and this has caught my attention. Plexis, JTMs and 1974x all have amazing cleans and light dynamic crunches and that's what I love about them so if this was an amp that maximised the enjoyment of that range of tones I'd certainly sign up for it!

Also replacing the TMB with a simple tone would mean I could use the other half of the 12AX7 for either a parallel input or series cascading stages for a higher gain option... 🤔
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AussieTim
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Re: SIII build from scratch

Post by AussieTim »

This is a nice sounding amp but is clean and really needs to be driven pretty full on to get much crunch.
I really like it but I already have an oversupply of clean amps with a Musicman 130 watt an original Blues deville a 5E3 I built and I am about to build a ab763 deluxe reverb Plus I have a little ashdown peacemaker as a "bedroom amp" and the beast that got me hooked on tinkering with amps a 1960s Rex Bassking amp an Australian amp built in Melbourne that pushes about 80 watts
So I will be changing this around, about half a dozen capacitors and a few resistors by the looks of the layout and schematics and seeing how it goes as a Plexi I can change it back if I dont like the noise it makes
After the Deluxe reverb I am probably going to make an 18 watt with tremolo probably go with an EF86 build as I do like Voxy sounds
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Re: SIII build from scratch

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AussieTim wrote:
Tue 01/10/23 7:52 am
Ok Ive been using this amp for six to eight months and Yes I am going to turn it into the plexi version, but at the moment I am attempting to build a cabinet for it using the plans that Modulus had on their website ( they seem to have disappeared with their web upgrade hopefully they will re-include their plans again, it was a great resource, luckily I had saved the 18 watt drawings)
Anyway I digress, what I would like is if any of you guys can steer me towards any information on cabinet building Tolexing etc. I would very much appreciate it.
I have trawled through this site I'm missing it.
Thanks
Tim
Hey Tim

Josh asked me to do a dedicated thread on cab building and tolexing. I guess it’s because he knows I always do my own cabs from scratch… and I have built suite a few the past years. Side effect if my ampaholism😁

I will do this thread in the near future, but do you have any specific questions at this moment? There are some tricky things you need to take into account when building, things you can’t undo.
- position of the supports for the baffle and back panels
- clearance around the baffle before tolexing and grill cloth
- clearance around the backpanels
- how to straight angle the cabinet
- how to tolex the cab, and in what sequence
- tolex the corners
- the most tricky part is the baffle itself, IE the tension and outlining the grill cloth. I have developped a very effective and easy way to do this. Believe me, everyone’s first attempt on this is plain awful.
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Re: SIII build from scratch

Post by JMPGuitars »

Bieworm wrote:
Tue 01/10/23 11:54 am
- the most tricky part is the baffle itself, IE the tension and outlining the grill cloth. I have developped a very effective and easy way to do this. Believe me, everyone’s first attempt on this is plain awful.
That's funny, I find the grille cloth the easiest part. I used to stretch canvases for painting when I was young, so that part is similar enough.
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Bieworm
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Re: SIII build from scratch

Post by Bieworm »

JMPGuitars wrote:
Tue 01/10/23 12:28 pm
Bieworm wrote:
Tue 01/10/23 11:54 am
- the most tricky part is the baffle itself, IE the tension and outlining the grill cloth. I have developped a very effective and easy way to do this. Believe me, everyone’s first attempt on this is plain awful.
That's funny, I find the grille cloth the easiest part. I used to stretch canvases for painting when I was young, so that part is similar enough.
No no… grill cloth is very stubborn fabric… unless you use the f€nder type of cloth. But the ones marshall uses are very nasty on the corners. Especially the blues breaker type of grill cloth. Canvas has a tighter weave and bends more consistently than the thick grill cloth material
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Re: SIII build from scratch

Post by Bieworm »

I first staple the cloth on the top side of the baffle … perfectly aligned. Then I turn the baffle upside down so the cloth faces the work bench. At the backside of the top side I screw a wooden beam the sticks put 10cm at each side. I flip the baflle back around with the clotch facing upwards and screw the beam to the work bench’s sufrace, with the bottom side of the baffle hanging an inch over the edge of the bench. Then I staple another beam to the very en of the grill cloth, perfectly alligned and parallel with the top beam. Now roll up the grill cloth with the bottom beam. Then I shove the old laptop bag shoulder handle over the ends of the bottom beam, and stretch the grill cloth over the bottom edge of the baffle with my hands. When I’m sure its nicely aligned I put my foot in the shoulder handle and press down very hard. That’s when I start stapling the cloth on the bottom edge.. not loosening the tension until it’s completely stapeled. That’s as tight as a drum head… the sides are easier…
9A796121-1439-4C72-AF30-EFA29D97E709.jpeg
A65B545F-F04B-4E7C-9DBF-B7458CA3988C.jpeg
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Re: SIII build from scratch

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AussieTim
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Re: SIII build from scratch

Post by AussieTim »

I am imagining how to do this with a baffle that has a valance
I am thinking that I need to start at the top edge under where the valance sits then pull tight onto the bottom then the sides
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