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PostPosted: 02 Mar 2021, 10:07 

Joined: 08 Feb 2021, 20:38
Posts: 8
Hi Members,

Still pondering my first hifi tube build and found this interesting DIY build by the late Fred Nachbaur titled, 'Simple, Single-Ended-Triode Amplifier' aptly titled, 'SET MiniBlok'. After much reading, I am intigued with an SET amp despite some of it's quirks. The entire parts for the MiniBlok are about $100. Seems like a good first build (for the poweramp section of a tube hifi system).

The SET MiniBlok is low cost and appears to be a project I can complete. Also, it appears to be an approachable first build as it does not require me to jump-in deep waters and spend upwards of $500+ in parts. Building a more expensive, complicated and involved SET Monoblock build may find myself not being able to complete it. Eventually I would prefer to build two SET Minibloks for stereo.

I have years experience in wiring, soldering and drilling out a blank chassis (from scratch).

This 'SET Miniblok' amp puts out 1 watt and as a result, I need to match it with high sensitivity speakers (a.k.a efficient drivers) in order to produce an acceptable and usable volume level.

Question #1 please:
Is Fred Nachbaur's 1-watt SET MiniBlok DIY tube-amp still considered a viable approach to a first build?

Question #2 please:
Has anyone reviewed this SET MiniBlok amp project?

Question #3 please:
Is there still support for this project? I sadly learned that Fred Nachbaur passed away in 2004. However his website is still being hosted. See link below for description:

Thank you very much for your help.



PostPosted: 02 Mar 2021, 14:43 
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Joined: 06 Apr 2009, 10:08
Posts: 1748
Location: US Pacific Northwest
Fred's design is one of the many using the dual triode xEM7 spud tube.

Personally I'd build this one (, but I'm biased. :D I'm also not a huge fan of the amount of solid state components in Fred's design. I tend to be more of a tube purist. But since I've never built it, I'll reserve final judgement.

You can read the thread on the 6EM7 amp ( to help you make a more informed decision.

Has anyone on the forum built Fred's design?

It's all about the Glass!
Cascade Tubes Blog

PostPosted: 14 Apr 2021, 10:55 
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Joined: 02 Sep 2008, 14:34
Posts: 531
Location: Rochester, NY
Other options to consider would include:

OddWatt Alpha
Bottlehead sEx

Cheers, Alan
Dennis Had Fire-Bottle | Bottlehead Quickie | Sony Changer | VPI Scout | CainTuck OB

PostPosted: 19 Apr 2021, 22:06 

Joined: 15 Feb 2020, 18:53
Posts: 30
You might consider building the 4S preamplifier. The parts would cost just over $100. You will still need a power amplifier to go with it but you won't end up spending money on a special set of speakers and you won't outgrow it immediately. I've built three and still use them all the time.

The first amp I built was an obscure 50c5 stereo amp that I actually still enjoy listening to. I think the other parts were around $200 but I got the tubes for free. It has the advantage of using 120v which is less scary than, say, the 300B amp I am building now with 800v transformers. Of course, even 120v is potentially deadly, so caution and proper protocol is always required.

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