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258v vs. 258r vs. 258p
MUFF WIGGLER Forum Index -> Buchla, EMS & Serge  
Author 258v vs. 258r vs. 258p
jvt
Need some help here. help Can anyone offer any insights as to the sonic and behavioral differences between these three 258 clones? I've already got a 258v but I can't help wondering how it differs from the other two. I'm already aware of the 258p's extended features beyond the original design. I'm not so interested in those from a comparison point of view. I'm more interested in a comparison of the sonics as related to the common feature set across all three.
mritenburg
I can't speak to the r, but v versus p, v fm is linear and p fm is exponential, so the fm is much deeper on the p, that's the major sonic difference from my perspective.
pre55ure
I'm assuming the "P" is Mike Peak's version?

I have an "r" and one built from Dustin Stroh's (J3rk) boards.
I think that peak's builds use Dustins boards?
In theory they should all be pretty much the same. Dustin's boards are based off of Mark Verbo's schematic, so those should be the same circuit. I think Roman's boards are based off the orginal schematic - but the only real difference there is that the "r" boards use the almost impossible to find ua726, and Verbos and Dustin's boards replace this with a THAT340. This swap is only in the exponential convertor and shouldn't effect anything other than the tracking (and the price).

So basically they are all the same circuit. Any difference in sound is most likely the result of trimming, part selection/tolerence, or (like the FM mritenburg referenced above) wiring.
sempervirent
258r rev3 uses CA3046 instead of UA726.
pre55ure
sempervirent wrote:
258r rev3 uses CA3046 instead of UA726.


That's interesting, I know that the newer BEMI easels are using the CA3046 instead of the UA726. I think there was a wiggler on here over in the DIY section who made a little smt CA3046 board that you could drop in as a replacement on the 208 V2 or V2.1.
Peake
AFAIK all of them use the same triangle shaper etc. I don't call mine a "P", just a "B" per its version, the 258B versus the majority of others being based upon the 258C, which as stated has linear FM instead of the B's exponential. Exponential FM can be added to the C versions. The Stroh/Verbos clones have a modern front end and track further (and might be more "stable"). The Roman clone is as far as I know a straight-up clone of the 258C with additional CV response scaling options. In terms of how each sounds, I've never done any comparisons between versions. I cloned the B because I used to have an A and a B in the vintage 151 system I used to own and know it's the sound for which I'm looking.

User jhulk offers a uA726 replacement daughter PCB.
papz
I offer a THT µA726 replacement PCB based on a CA3046.
It works very good and is available in 2 formats, one for the 208 and one for other circuits.
http://www.portabellabz.be/pa726.html
jvt
Thanks for all of the input.

@Peake I only used the "p" prefix to help differentiate between the three clones I was aware of.

Perhaps it's the exponential FM that I'm interested in. From the examples I've heard the Peake version seems to have that but they don't come up for sale very often. If mritenburg is right then Roman's clone might be a reasonable alternative.
mritenburg
jvt wrote:
Thanks for all of the input.

@Peake I only used the "p" prefix to help differentiate between the three clones I was aware of.

Perhaps it's the exponential FM that I'm interested in. From the examples I've heard the Peake version seems to have that but they don't come up for sale very often. If mritenburg is right then Roman's clone might be a reasonable alternative.


I made a quick clip comparing Peake's 258b and Verbos 258v. I used the same modulation source for both: 258b through 292 to dynamically control depth with 281 in quadrature mode so the left channel is modulated, then right, then repeat. The 258b is in the left channel and the 258c is in the right channel. The 258b fm is at 70% and the 258c fm is at 100%. They sound very very close, though you can hear the exponential curve as depth of fm increases on the 258b. At the :33 mark I increase the 258b depth to 100% then back to 70% at the :45 mark.

http://www.la-belle-aurore.com/audio/258b_l_258c_r.wav
Peake
Is that at the factory FM depth or the extreme FM offered by removing the cap and lowering the resistor value? It's not hard to add the expo FM to some of the "C" type clones, requires switching the audio input signal through a resistor (and cap if desired, factory was 33K plus 1uF) to one of the two CV input paths found on either side of the CV input amount pots. I modded a Roman 258 version 2 for switchable linear/expo FM, wasn't very difficult. Version 1 may be a different story due to requiring to trace through the input paths to the main PCB. Most of the "B" clones I've done offer a factory/extreme FM switch as well as alternate waveform switching (saw/square per oscillator), the latter also being possible on perhaps all "C" clones with sufficient wiring and a flying resistor or so. Several wires to a 3PDT switch per oscillator. L1 at electro-music discovered this possibility and the Verbos/Stroh 258 DIY PCBs are easy to wire for it. On the Stroh the expo path, after the resistor and any cap, is soldered to where the 100K input resistors meet on their way into the opamp.
mritenburg
Peake wrote:
Is that at the factory FM depth or the extreme FM offered by removing the cap and lowering the resistor value?


I'm going to guess factory setting. It's one of your 258b modules with all the mods. The toggle switch for FM depth is in the up position.
jvt
mritenburg wrote:

I made a quick clip comparing Peake's 258b and Verbos 258v. I used the same modulation source for both: 258b through 292 to dynamically control depth with 281 in quadrature mode so the left channel is modulated, then right, then repeat. The 258b is in the left channel and the 258c is in the right channel. The 258b fm is at 70% and the 258c fm is at 100%. They sound very very close, though you can hear the exponential curve as depth of fm increases on the 258b. At the :33 mark I increase the 258b depth to 100% then back to 70% at the :45 mark.

http://www.la-belle-aurore.com/audio/258b_l_258c_r.wav

Thanks for making the clip. Probably a better question would have been: are the *audio* (not CV) inputs expo or lin on the different 258 clones? I can send audio rate modulation from a 259e (banana) to the expo CV input (banana) on the 258v which gives me a result closer to what I'm after. But of course that input is not attenuated so it's either all or nothing without introducing some other module to convert and attenuate 258v audio to CV. I can not attain that level of cross-modulating using only the 258v audio outputs/inputs.
mritenburg
jvt wrote:
mritenburg wrote:

I made a quick clip comparing Peake's 258b and Verbos 258v. I used the same modulation source for both: 258b through 292 to dynamically control depth with 281 in quadrature mode so the left channel is modulated, then right, then repeat. The 258b is in the left channel and the 258c is in the right channel. The 258b fm is at 70% and the 258c fm is at 100%. They sound very very close, though you can hear the exponential curve as depth of fm increases on the 258b. At the :33 mark I increase the 258b depth to 100% then back to 70% at the :45 mark.

http://www.la-belle-aurore.com/audio/258b_l_258c_r.wav

Thanks for making the clip. Probably a better question would have been: are the *audio* (not CV) inputs expo or lin on the different 258 clones? I can send audio rate modulation from a 259e (banana) to the expo CV input (banana) on the 258v which gives me a result closer to what I'm after. But of course that input is not attenuated so it's either all or nothing without introducing some other module to convert and attenuate 258v audio to CV. I can not attain that level of cross-modulating using only the 258v audio outputs/inputs.


That clip is using the audio FM input. The audio FM is expo on the 258b and linear on the 258v
Peake
Odd because the extreme setting can produce pitched noise on the B or a modified C. It's possible the cued part of the below example was two oscillators cross-modulating (which is the most important patch) but the section just before shows hot one-on-one oscillator modulation at the extreme setting. Significantly deeper than the "B versus C" comparison demo.

https://soundcloud.com/peake-1/258b-special-edition-basics#t=2:47
jvt
Peake wrote:
Odd because the extreme setting can produce pitched noise on the B or a modified C. It's possible the cued part of the below example was two oscillators cross-modulating (which is the most important patch) but the section just before shows hot one-on-one oscillator modulation at the extreme setting. Significantly deeper than the "B versus C" comparison demo.

https://soundcloud.com/peake-1/258b-special-edition-basics#t=2:47

YES!!! That's what I'm after! Dancing Star Can't quite get there with the 258v.
Peake
Mark may be willing to add a switch and signal path for expo FM, shoot him a message. It's basically switching the output of the FM amount pot between the linear input/cap/resistor and something around 100R-1K to the expo CV input.
jvt
If Mark was still in the US I would. But the last time I shipped a module to him in Germany it was about a two and a half month turnaround. The biggest chunk of that time was dealing with customs.
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