A ModulusAmps kit nearly there.... (title edited!)

Kalimna

Greetings Folks,
Ive had this kit for a while, and as I tend to do its taken a while to move beyond the initial new-toy stage to actual construction. This is a recreation of the mofified JCM800 used on Appetite for Destruction and is my 2nd kit from @Modulus_Amps , the first being a JTM Black Flag (glorious clean and overdriven and a royal pain to tame volume despite the added MV).

I am not planning on any modifications this time, as the amp already has a MV and the circuit seems a little more complex to start with. Instead, im going to try and concentrate on improving neatness of wiring.

So, the turret board is being populated. Wire links went first, followed by a left-->right approach for the remaining components. I would have liked to keep the component leads a little straighter, and neater when bent to accomodate space issues. But didnt want to overdo it and risk breaking leads. 

The photo's should be self-explanatory, and though some of the solder joints look a little bare, there is plenty of solder that has flown down the turrets. It seems to be a very 'fluid'solder that im using.

I'll get the board finished today (component wise) and make a start on the chassis later.

As always, comments and critique is welcome. And a very positive shout out to Michael at Modulus for sterling advice, patience and product!

The mostly bare turret board
https://i.imgur.com/luA0oLk.jpeg

Close up of diode array
https://i.imgur.com/uBtB4UJ.jpeg

Further close up of 'interesting' component lead bends.
https://i.imgur.com/Xgra3kP.jpeg

The board as it stands
https://i.imgur.com/VPlXIDe.jpeg


Cheers for looking

axisus

When I saw Modulus I thought Bass kit!?!?! Seems strange a company having the same name. 

Anyway, looks an interesting project! I'll be back to see how it goes. All that wiring looks a tad daunting, although I guess the instructions are clear.

I'm off to check out the company ...

PeteC

Very nice - might be worth using an insulating sleeve on that resistor leg in the bias supply that goes next to that turret. Should be fine but if the amp takes a serious knock etc it might touch. 
Should be a very good amp! 

DLM

axisus said:

When I saw Modulus I thought Bass kit!?!?! Seems strange a company having the same name.

Ditto

I knew they did replacement necks which were popular for a time.

Kalimna

PeteC said:

Very nice - might be worth using an insulating sleeve on that resistor leg in the bias supply that goes next to that turret. Should be fine but if the amp takes a serious knock etc it might touch. 
Should be a very good amp! 

Thanks for the comments Do you mean the turret just below the variable resistor? If so, thats not actually attached to anything but I can heat shrink anyway.

PeteC

yes - I meant that the resistor leg looks to be almost touching the turret and if the turrent was connected to anything else in the amp...well, potential smoke etc!  But if the turret is just spare then no issue - or take it out? 
Good luck with the build - you can't beat a great PTP valve amp. 

Kalimna

Thanks again - this amp building is rather addictive isnt it? I am also halfway through something with my youngest offspring and know which amp to attempt next

Modulus_Amps

Great stuff, the kit is actually based off the amp used on UYI and onwards, which was SIR # 34 and is the amp Marshall brought in to look at when designing the AFD amp, The AFD has an additional gain stage with slightly different tone shaping.
When you get there I can help you try out different things to get the best from the amp though. 

Kalimna

Modulus_Amps said:

Great stuff, the kit is actually based off the amp used on UYI and onwards, which was SIR # 34 and is the amp Marshall brought in to look at when designing the AFD amp, The AFD has an additional gain stage with slightly different tone shaping.
When you get there I can help you try out different things to get the best from the amp though. 

Ooops. My mistake regarding the origin, sorry!
I'll get some of the chassis wired up today, but im off next week, partly Covid+ve enforced, so hopefully get it mostly finished by next weekend.
Thanks again,
Adam

Kalimna

The *nearly* complete populated board. Just a couple more resistors to go, then the offboard wiring.

https://i.imgur.com/BMZWo7h.jpeg

https://i.imgur.com/Uvzfw8N.jpeg

https://i.imgur.com/CcQRDNV.jpeg

Adam

Kalimna

Greetings again. A few days isolating has given me a bit of time to crack on with the amp build. Overall, I think my wiring is getting neater, and i would be very grateful for any experienced builders to weigh in here. However, a couple of areas continue to be a royal pain in the butt - the large (filter?) caps with 3 terminals seem designed to cause stresd. Twisting the heater wires neatly. And with stranded wire, how do keep everything neat???
Anyway, here are some photos.

First chassis soldering - the AC socket. Heatshrink is much easier with a small hotair gun.

https://i.imgur.com/IIgD9Jg.jpeg

And the start of the heater twisting

https://i.imgur.com/fo0rZI9.jpeg

Input jacks and some of the control pots. Relatively thin gauge shielded wire a little more awkward than the 22AWG used elsewhere. There may be a better way to attach the parallel cap/resistor.

https://i.imgur.com/ejFjlA2.jpeg

Hooking the offboard wiring around the turrets via threading the wire through the board. Again, trying to keep things neat.

https://i.imgur.com/tq7iHse.jpeg

Offboard wiring attached. A million spiders legs.

https://i.imgur.com/fQxELct.jpeg

Now the real fun begins. Transformers attached and cables through.

https://i.imgur.com/hK81QzA.jpeg

The caps-of-doom. Another 5-6 wires to attach. Note the other wires providing easy access for the soldering iron tip....

https://i.imgur.com/B5tSUMe.jpeg

Close up of on/off switches

https://i.imgur.com/KgHXMlQ.jpeg

Pre-amp bases. Not too bad.

https://i.imgur.com/a2H9D6w.jpeg

Power bases. Getting worse.

https://i.imgur.com/l3lSQ5N.jpeg

Caps-of-doom. Spaghetti vomit

https://i.imgur.com/EUwldus.jpeg

As it now stands. I need to replace a resistor after trimmimg the wrong side of the solder join. And i cracked a fuse holder that also needs replacing.

https://i.imgur.com/o01gytp.jpeg

As always, comments welcome and criticism accepted as advice

Cheers,
Adam

elstoof

It’s not easy with stranded wire eh. A bit of heat on the jacket then holding it in place while it cools can help it stay put

andy_k

I admire your devotion to the cause of great amps, any chance of a pic of your previous build, the black flag?
Basically these are my 2 favourite amp designs, and I'd love to build one, but you know, electricity and all that.
I have to run my 50 watt JCM900 through a powerbrake, which is obviously strangling it, but by god, the tone of it is glorious, can only imagine how nice yours must sound, fingers crossed the new one works first time.

Kalimna

elstoof said:

It’s not easy with stranded wire eh. A bit of heat on the jacket then holding it in place while it cools can help it stay put

Thats something Id actually considered, as i noticed the plasticity increases with heat. Unfortunately, all I achieved were slightly more unsightly kinks in the wire! Trial  n error n all!

andy_k said:

I admire your devotion to the cause of great amps, any chance of a pic of your previous build, the black flag?
Basically these are my 2 favourite amp designs, and I'd love to build one, but you know, electricity and all that.
I have to run my 50 watt JCM900 through a powerbrake, which is obviously strangling it, but by god, the tone of it is glorious, can only imagine how nice yours must sound, fingers crossed the new one works first time.

Devotion/perserverance/madness - its hard to tell which! Ive been running the Black Flag through a hotplate, but Im not convinced Im getting the best out of it. It truly does sound glorious at volume though Whereabouts are you? You're very welcome to try it out.

I thought Id already posted up the Black Flag, but I cant seem to find the thread. Let me sort out some pix and maybe an open A soundbite.

Cheers,
Adam


P.S My little boy, Isaac, and I have also finished the turret board on a Tweedle Dee kit, also from Modulus. I'll put up a separate thread for our joint build

elstoof

I put a super deluxe kit from modulus together a few months ago, went together nicely. Just need to make a cab for it now. Currently soldering a Trinity TC15 whenever I get the chance though, amp building is good fun!

PeteC

Looks great - don’t worry too much about super neat lead dress so long as all your solder joints are good.  You may find yourself having to un-neaten  carefully routed and bunched signal wires anyway after it’s finished to make the amp as quiet as you can - especially grid wires.   It’s happened to me quite a few times.  

It will be an amazing amp - and LOUD !! 

Kalimna

Thanks PeteC, the loudness should hopefully be tamed by the MV   The BlackFlag 50 however, despite an added MV, is quite loud. Room shatteringly so!

I think the solder joints are all good - even if they look a little 'empty' on some of the turrets. I was finding that the solder was flowing in a more 'liquid' fashion than Im used to (Michael had donated some fancy lead-free solder to trial), and that  it tracked right down into the turret holes. The only real worry I have, solder-joint wise, is on the big caps (the 3-terminal blue beasties), and fitting all the connections to a small tab. Plus the ground connection on said caps is awfully close to the chassis itself. I'll be taking the amp up to Michael @Modulus for a check-over before I power it up anyway.

Cheers,
Adam

PeteC

Where i have had to solder multiple connections to a power supply cap i sometimes use a short piece of solid copper wire through the lug first and use it as a terminal for all the other connections.  This way you can keep it all neat and it makes removing any individual wire easy if you need to in future      I do the same with any star earths - often making a small ringlet of heavy gauge copper as the terminal.  

Kalimna

PeteC said:

Where i have had to solder multiple connections to a power supply cap i sometimes use a short piece of solid copper wire through the lug first and use it as a terminal for all the other connections.  This way you can keep it all neat and it makes removing any individual wire easy if you need to in future      I do the same with any star earths - often making a small ringlet of heavy gauge copper as the terminal.  

I have come to the conclusion that that will be my approach next time. And perhaps I should have done so already. I'm working again this weekend, but will hopefully have some more photo's to post up  by next week sometime.

So. Other than that, what amp *should* I try and recreate next?

Adam

PeteC

Trainwreck express or Rocket gets my vote  - or a small Supro/ Valco for those jimmy page vibes 

Vinylfan

Really interesting to see the build coming along. Thanks for sharing