I’ve recently added a Moog MF-104M & MF-104Z to the arsenal. I didn’t originally plan on keeping both, but they ended up being very different beasts. The 104M has fuller bandwidth, smoother sound, & modulation. Not to say that you can’t drive the hell out of it, It’s covers a lot of sonic territory. The 104Z has a grit & chaotic feedback loop that I love. I pulled out the D-Scope & analysed the two. You can see the frequency response & THD+N of the dry signal & the BBD Short/Long delay modes in the images below.
I shot a comparison in my dimly lit room. The 104M audio is in the Left channel & the 104Z is the Right. The last 2 minutes or so show off the self oscillation.
Setup
- Instrument – MFB-522 / Rhodes MK1
- Gate/under-clocked BBD – KOMA BD101
- Delay MF-104M / MF-104Z
Great to see the plots. They closely match what I took as well using ARTA and a MOTU interface. Looks like you may have the feedback up or the gain not the same on the 104Z though as I didn’t get that much LF loss on my unit.
Feedback was down, I’ll check if the response changes with different gain settings. I played with input levels to find the loweset THD. I ended up sending them both -18 dbu. I did notice compared to the 104z the 104m can push out more level from output stage if needed.
Yes the 104Z uses the straight output of the OTA. The 104M buffers the OTA with a darlington pair. The OTAs also have sightly higher bias current for more gain. So it is not so much that the 104Z has a lower output but a higher output impedance and hence the output level can’t drive as hard. Couple that with higher headroom (near rail to rail) op amps in the 104M and you can get a hotter level.
Great info, thanks for that.
HI, Great videos! I’m deciding which to buy between Moog and Koma. What would you say it’s their main difference, and which is best for synths? Thanks a lot!
The mf-104 is straight up classic delay bliss. The BD-101 is a LFO driven gate + under-clocked delay that can sound like a bit-crusher.