Superlite Component Questions

18watt-specific Tech Talk - Building, Fixing, Parts, Mods...

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DrRogersA
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Joined: Fri 10/21/22 12:14 pm

Superlite Component Questions

Post by DrRogersA »

Greetings, everyone. If I may, I'll introduce myself right quick and then ask some questions regarding choosing components for an 18W Superlite TMB Build.

I have been building pedals for several years, and lately I've had the hankering to try my hand at amplifier building. I only have solid state amps, so I get a little embarrassed when talking gear with my friends. And I'd much rather build than buy. For me, it's as much about the experience as it is about the finished product. I have a background in Electrical Engineering (and a PhD in Computer Engineering), so I'm very comfortable reading schematics, soldering, etc. Working with valves (or "glass-FETs" as one of my coworkers calls them) is rather different from working with solid state devices, but I've been doing a lot of reading and I think I understand the basic theory of how they work. I've also worked with high voltages before, so I am very aware of the dangers and necessary safety precautions.

After poring over a great many schematics, layouts, etc. I finally settled on building an 18 Watt Superlite TMB as my first project. I decided to spec out and order all the parts myself rather than go with a kit. I want to do as much as possible on my own to maximize my learning. I intend to start ordering components now, and kick off the build in the new year.

I'm using the schematic and layout posted at the top of this thread:

viewtopic.php?t=24430

Now on to my questions. This is just a first round; I'll probably come up with more as time goes on. I thank you in advance for my patience.

Cathode Bypass Capacitors:

The schematic calls fore three cathode bypass capacitors, a 0.047 uF and optional switchable 1uF on V1-A, and a 1uF on V1-B. I've noticed these specified as electrolytic on many schematics, but this schematic shows non-polarized caps. What would you folks recommend for these three bypass caps? Type? Manufacturer? Series? Voltage rating? (Mouser part numbers? :mrgreen: )

Transformers:

Here's where I encountered a bit of sticker shock. I see Hammond at the low end of the price range, Mojo in the middle, and Mercury at the high end. These are the transformers I've been considering (I suspect they're rebranded Heyboers):

https://www.mojotone.com/British-Style- ... ransformer
https://www.mojotone.com/British-Style- ... ransformer

Are these okay?

I nearly choked when I saw the prices for Mercury Magnetics transformers. Are they that much better than these Mojos? Should I bite the bullet, and perhaps get a Mercury output transformer? It seems that many builders liked ClassicTone, but they don't appear to be available now.

I don't have enough experience with transformers yet to distinguish cork sniffing from legitimate concern, so I would appreciate some wise counsel.

Nuts and Bolts:

I feel I am the weakest when it comes to the mechanical aspects of amplifier construction. I suspect I should stock up on things like nuts, bolts, washers, lock washers, standoffs, etc. But I have very little idea what to get. Could someone make some recommendations on some commonly used items that I should have in my drawer?

Thanks in advance.

Dr. Rogers
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