SW 901a/b available at SYNTH-WERK.COM
You do realize the irony of your chosen username and your first and only post being an advertizement, don’t you?
I don’t know why, but I have the feeling that we might not see him here again… 
Even when it’s about synth stuff, I hate spam. Especially when it’s the first and only message from someone on a forum… 
. .
I do not exactly understand what the problem is???
What is wrong with announcing the availability of a legendary moog module as a clone in a moog forum…
I really don’t see why this is spam. It’s on topic and certainly not unwanted ! There are plenty of self-promoting posts here, nothing wrong with that as long as it’s on topic IMO.
It seems to me that if you have any interest in MU modular gear whatsoever, you should take a look at what these guys make !!
It’s not exactly a “problem” per say. It’s just that it looks peculiar to arrive on a forum without any presentation about yourself (at least a couple of words) and right away advertise a link for a commercial product, even though it is synth related…
Anyway, welcome to the forum anyhow. 
Sorry to have seemed a bit harsh before, and let’s hope you have something more to contribute than just advertisement ? 
My only (opening) comment is that, after working on over 100 901Bs, I know that triangle waveform glitch shouldn’t be as pronounced.
Usually it happens because of aged resistors or miss-set trims.
Since this builder is only using precision components, it suggests he believes it was a feature to be copied and not an undesired quirk to be eliminated.
I’d like to hear some sound clips. The Moog 901b is an awesome sounding oscillator, maybe the best
I’ve ever heard, not withstanding the tuning issues associated them. I recently saw a Don Martin Moog 901b go for over $600 on ebay 
It will be interesting to hear how these Moog clones sound 
Thanks for posting !
Hi Kevin,
the design of the 901b was not changed at all. We did a new board design and used as you mentioned high quality components. We compared the waveform to several 901b of different years and the waveform was more or less exactly the same. Also from a sonic point of view it was the same. So it is very interesting what you saying because you habe a lot of expierience with this oscillator. One musician explained the difference between the 901b and the 921b like the differnce between red wine in a plastic bottle and red wine in a in a oak-timber barrel…thank you for your input
regards
Gerhard
p.s. we will come up with sound samples of different artists soon, this is in progress…
Thank you for your thoughts, Gerhard.
I think perhaps some 901Bs used selected resistors or could have even been originally prototyped and built with resistors that weren’t quite accurate.
Same could go for matching of transistors.
I really don’t know.
All I can say is that the glitch isn’t always there or as large as what I see in your photos.
The phase of where it occurs can vary sometimes too, but I think ideally it’s supposed to be a very narrow glitch exactly at the top.
I’ve seen many 901Bs that had triangles as perfect as this described above, so I assume this was Moog’s goal.
Given the simple design, it’s the best one could hope for too.
I certainly do understand that having a pure sine wave is desirable and as you’ve probably discovered, trimming the triangle to be more perfect might make for a less perfect sine, but I do think the original design consideration was for a better triangle in the first place.
The better the triangle, the better the sine anyway.
I also agree that one might not hear such a glitch at audible rates, but if used as an LFO or clock, it might be a problem.
Finally, I do admire the work you put into these units.
I can understand how hard it is to match capacitors for range switches and many of the other processes you must have done.
So I commend you on your work. 
Oh and just in case you’re interested, I have many original (NOS) Moog panel screws of the type you instead used hex (allen wrench) types for.
As for 901s vs 921s, that’s like comparing dogs and deer.
The closer one looks, the more differences you can see.
I don’t even compare the two.
FWIW, SYNTH-WERK.COM has been posting over on Muff’s forum for a while now and also works with Moon Modular etc. He seems like a good guy making good products (and takes good pictures too, well worth a visit to his website!)
Thank you for your feedback, Kevin.
As you can imagine it was a very rough ride to come this far with the 901b. We startet this project about 2 years ago with all kind of up´s and down´s. But the sound of the 901b always kept the spirit high. We have reached a Frequency stability of 0,2 Hz over a period of 3 month (could be even longer…) and good tracking accuracy over 3,5 Octaves. We have been scanning the planet for “good” 2N2646 and CA3019 and finally have the quantity to offer the 901a/b. Concerning the glitch on the triangle waveform you mentioned we will check what the impact of the adjustment to the sine wave will be, but like you say from a sonic point of view, especially after the CP3 and 904a, there is no impact.
Your words mean a lot to us! Thank you very much.
Thank you for your recommendation John!
What is the price for a single 901B shipped to the US? Thank you.
Because of the intensive work to tune a 901a/b bank for good tracking over approx. 3,5 Oct. we decided to sell only the complete bank. This will include 1x 901a and 3x 901b. We also strongly recommend the CP3 as the combining mixer for the oscillators. Price is 1.200 Euro plus shipping.
If you need a single 901b to extend an existing moog 901a/b bank we can do this but we need to talk about the power supply requirements you have and also you need to do the tracking adjustments on your own.
cheers
Gerhard
Okay, thank you for the info. Do your 901a/b modules use the same voltages as the original Moog modules? I’m not currently ready to add more modules, I just wanted to get an idea if the opportunity came up.
All modules follow the moog format and come with the standard „.com“ connector for easy integration in existing systems. The modules work with supply voltages of +15/-15 Volt. Each module has it`s own power regulation to +12/-6 Volt.
As a .com owner myself, I can appreciate this offering! 
The dual regulators in these modules is actually a very smart idea.
Besides that it can accept various power sources, having each VCO separately regulated allows them to be moved around in a system without fear of varied loading or power wire resistances.
It’s what Polyfusion did on their VCOs and what Oberheim did on their SEMS and Minisequencers.