# Retro-Sonic Flanger



## weaksauce (Mar 20, 2006)

https://www.retro-sonic.com/flanger

Looks to be a modern version of the old 18v Electric Mistress...

I’ve never had a flanger pedal, but this tempting me!


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## mhammer (Nov 30, 2007)

This is interesting. Those that follow _That Pedal Show_ will know that Dan is very attached to his Electric Mistress. Last year, he contacted Joel Korte of Chase Bliss Audio, and asked if Joel could make him a work-alike, so that he didn't have to risk bringing his original to gigs. Joel contacted me and asked if I wanted to work on it with him. I indicated I was able to provide ideas for additional features not included on the original, but not really up to the task of working out the specific technical details. Undaunted, Joel then approached Tim Larwill, who makes the Retro-Sonic pedals. Tim is another Ottawan. I've known Tim for many years, consulted on a few of his pedals, and the three of us have met several times. I gather that Joel probably became pre-ocuppied with development of the two pedals he debuted at NAMM 2019, and it eventually turned into Tim's solo project. Tim has previously made a very well-received replica of the Boss CE-1, so there is no reason why he couldn't do just as good a job with the Electric Mistress.

I don't know this for sure, but all the facts line up. I would expect to see Dan and Mick using the Retro-Sonic on a future episode of TPS, and I expect to see Dan smiling broadly. Joel sent me a pic of Dan's pedals that he was wanting clones of, so you can see what version Tim likely cloned. That version used a Reticon SAD-1024, which would be unobtainable in the quantities needed for a commercial run, so I gather Tim used a different delay chip and adapted the circuit appropriately to mimic what the original did. Poking around, it seems that effect/bypass level balance is a historically recognized issue with this version, and is probably exacerbated by using true-bypass switching. So the inclusion of the Level control will make many users happy.

I'm going to have to pop Tim a note, and congratulate him


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## weaksauce (Mar 20, 2006)

How cool!

I do watch That Pedal Show. It will be interesting to see when/if they feature it in an upcoming episode.


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## JC103 (Oct 6, 2007)

Wow! That is cool! It will be interesting to see what tweeks have been made. I have a pair of the older Madbean Current Lovers with the MN3007 biased for 12v operation. They sound good, but I can't help hearing a CE-2 flavour in there at times due to the bbd's sonic signature. I heard MN3009s were going to be released by Xvive this year.


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## mhammer (Nov 30, 2007)

Small Bear Electronics already carries them. Xvive has also brought back the MN3007.


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## JC103 (Oct 6, 2007)

Emailed Tim at Retro-Sonic, these will be ready fairly soon with a second batch coming in March. $199USD.


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## mhammer (Nov 30, 2007)

The inclusion of a volume control will likely please many. Looking at some forum threads in other places, some report a volume drop from vintage EMs. So being able to have effect and bypass levels properly matched, or be able to kick in a small amount of boost for effect solos and such, will be welcomed.


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## weaksauce (Mar 20, 2006)

I ended up getting in on the preorder. Can’t wait to try it out!


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## zerorez (Jul 4, 2008)

Anyone get one yet? any reviews?


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## Boogieman (Apr 6, 2009)

Found this on YT:


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## mhammer (Nov 30, 2007)

Not much of a demo, but at least it means Tim has them out in circulation.


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## Granny Gremlin (Jun 3, 2016)

JC103 said:


> Wow! That is cool! It will be interesting to see what tweeks have been made. I have a pair of the older Madbean Current Lovers with the MN3007 biased for 12v operation. They sound good, but I can't help hearing a CE-2 flavour in there at times due to the bbd's sonic signature. I heard MN3009s were going to be released by Xvive this year.


How do you find the Current Lover for noise and volume drop? I got one in the build queue but not got to it yet. Probably for the best because now the 3007/9s are back out vs risk of fakes on ebay. I forget what chip I originally grabbed to use for this thing.


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## mhammer (Nov 30, 2007)

While the 3009s are certainly suitable for achieving very short delay times for the odd "jet plane" sweep, at only 256 stages, they are less suitable for producing longer delays. You can GET them to produce longer delays by simply clocking them slower, but the problem that creates is that the slower clocking needed to achieve, say, 10msec with 256 stages demands more lowpass filtering to keep the clock noise inaudible. In some respects it is preferable to use a 1024-stage or 512-stage device, in conjunction with clock-buffering circuitry, that enables the chip to reach "the heights" needed for jet plane sounds, while still achieving the longer delays needed for ultra-wide sweeps without sacrificing too much top end. Many authorities in the field will recommend a sweep ratio of greater than 30:1 being desirable for flanging. So if the shortest delay time achieved was 300usec (1/3 of a millisecond), you'd need to be able to achieve a maximum delay of 9msec or more, and that starts to run you into dangerously audible territory for the clock.

The old Roland Juno-106 (and I suspect some other synths) used a pair of MN3009 chips for their chorus sound. But keep in mind that it was *chorus* (hence fairly modest sweep), and that synths have MUCH greater bandwidth than guitars so even a fairly narrow sweep in a very high range (i.e., short delays) would still yield quite audible swirl.


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## Boogieman (Apr 6, 2009)

mhammer said:


> The old Roland Juno-106 (and I suspect some other synths) used a pair of MN3009 chips for their chorus sound. But keep in mind that it was *chorus* (hence fairly modest sweep), and that synths have MUCH greater bandwidth than guitars so even a fairly narrow sweep in a very high range (i.e., short delays) would still yield quite audible swirl.


And TC Electronic is about to release a pedal that is a clone of the Roland Juno-60's chorus section.

|JUNE-60|Tcelectronic|P0D8E


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## mhammer (Nov 30, 2007)

Yes, saw that. Two buttons. Hard to get more minimalist than that.


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## JC103 (Oct 6, 2007)

Granny Gremlin said:


> How do you find the Current Lover for noise and volume drop? I got one in the build queue but not got to it yet. Probably for the best because now the 3007/9s are back out vs risk of fakes on ebay. I forget what chip I originally grabbed to use for this thing.


Which version do you have? MB updated the pcb to run only the 3007 in 2016 I think. I don't like that one because he switched to an opamp gain stage at the output to address the volume drop. The previous version uses a transistor and can be configured to run either the 3207 or 3007. I initially had the 3207 in there and then swapped it for the 3007. At the time I thought it sounded better, but now I'm not too sure. I thought running it at 12v would be "better" and it definitely gave it a deeper sweep but the voicing is not quite right for achieving the sound of the 18v V2 from 1976 or so. A good option, but not a straight up replacement. I actually think the Current Lover sounds better with a bit of a volume drop, I set the output level to be just a pinch below unity.

Any idea if 3009s can be run in series for 512 stage total?


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## mhammer (Nov 30, 2007)

JC103 said:


> Any idea if 3009s can be run in series for 512 stage total?


You can run pretty well any BBD in series with any other BBD from the same family. So, a 3009 in series with a 3007 in series with a 3008, if you felt like it. HOWEVER, there is no guarantee that their individual bias voltages will be identical. When the MN3005 disappeared from the landscape (well before Xvive brought it back), Maxon cascaded *eight* MN3007s to make their AD-999 delay pedal (ignore the numbers; those are proprietary house numbers), with each BBD having its own bias and balance trimmer.

Really, you'd be far better off to simply clock an MN3007 (or even 3207) twice as fast, than to waste a pair of MN3009s, and have the nuisance of tweaking two sets of trimmers.


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## mhammer (Nov 30, 2007)

duplicate


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## Granny Gremlin (Jun 3, 2016)

JC103 said:


> Which version do you have? MB updated the pcb to run only the 3007 in 2016 I think.


The updated one. Can only run on 9V apparently. I think it has been updated again since.

Thanks for the info! I've never used the original so just looking for a good flanger. Any idea is the fx loop (ostensibly to enable through zero flanging) is worth it. Really cramps the box and I loathe to use side jacks unless there's good reason.


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## weaksauce (Mar 20, 2006)

Got the email that mine is on the way! Should be here this coming week.


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## Boogieman (Apr 6, 2009)

mhammer said:


> Joel sent me a pic of Dan's pedals that he was wanting clones of, so you can see what version Tim likely cloned. That version used a Reticon SAD-1024, which would be unobtainable in the quantities needed for a commercial run, so I gather Tim used a different delay chip and adapted the circuit appropriately to mimic what the original did.


The Retro Sonic site mentioned MN3207 for the Flanger.


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## mhammer (Nov 30, 2007)

Again, for those less of the "chip-wonk" persuasion, the advantage of the Reticon SAD-1024 was that it could clock very fast and achieve ultra-short delays without requiring additional support circuitry. That was what allowed early "minimalist" flangers using that chip to sound great. But once you include that support circuitry, the less glamorous Matsushita/Panasonic chips can be pushed to significantly faster speeds.

The fairly standard Boss BF-2 uses an MN3207 (recommended max clock speed = 100khz). Just like the datasheet for the chip indicates, it craps out at 1msec delay time. Shorter delay times are required to achieve dramatic jet-plane swooshes. The ones that impress us may clock much higher and achieve delays at or below 300microseconds (3/10 of a millisecond). Keep in mind that, as "bucket brigades", the faster the buckets are handed from stage to stage in the chip, the less time it takes for the signal to get from the input to the output. So faster clocking speeds = shorter delay times. I've witnessed MN3xxx chips pushed to ridiculous extremes (e.g., 15x the indicated maximum clocking rate) under the right conditions.

The MN3007 has slightly better specs than the MN3207, but raises the production cost noticeably, and has fewer sources available. No harm done using a 3207 for Tim's EM clone.


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## Boogieman (Apr 6, 2009)

Received my Retro-Sonic Flanger a few days ago. Had a bit of a problem when it was placed after the buffer (Empress Buffer+). It would make some weird R2D2 noise at intervals relative to the RS Flanger's Rate and Range controls, starting with the Range control at 1 o'clock and beyond. No issues with a guitar plugged straight to the Flanger, though. Since then, I have placed the buffer after the RS Flanger and problem solved.

I have another Empress Buffer+ on my bass board. Hooked it up in front of the RS Flanger and the R2D2 noise came back. It was the buffer, indeed.

Back to the RS Flanger. I've never owned a vintage EHX EM, but I did have a vintage EHX DEM for quite a few years. The RS is not a dead-on clone, but it sounds very good and very close to what I had imagined a vintage EM would sound like. The Level knob is a nice feature to solve that volume drop problem.

While I was playtesting the RS Flanger, I recorded a short clip for my own reference. It was a quick and dirty sketch:


__
https://soundcloud.com/boogie-man-130457683%2Frsflangertest

I played the same phrase 3 times: Straight; RS Flanger turned on; RS Flanger with a EQ pedal.

Fender '60s RI Strat with Lollar Blonde middle (RWRP) and bridge PUs>RS Flanger>Mesa 5-band EQ (set to the V-curve, with [email protected] and [email protected] Third run only)>Empress Buffer+>Boss BR-800 recorder. No other effects used for either pre or post-tracking. I ran 18v on the RS Flanger.

I did the third run with the EQ added to boost the hi-mid and high frequencies, just to see if I can get a more chimey tone.

The RS Flanger sounds good as it is. I doubt if I would use it all the time, but it is a keeper.


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## mhammer (Nov 30, 2007)

I'm sure it's capable of producing some sounds that are UNpleasant, as is pretty much any flanger, but that's a nice clear, relaxed swirl, comparable to some of the best EMs.


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## JC103 (Oct 6, 2007)

Here is a decent comparison.






I don't hear it sounding better than any of the other attempts by Madbean or Harman. Long Amp just used the Madbean boards, so that one doesn't count as a separate version. What would be amazing is someone actually getting close while not using the SAD1024. My gripe with the clones is that no one never bothers to run 2 delay lines like the original configuration in the 76 V2. There really is something to that (I know, that would require two chips). Also, thinking out loud here... but maybe there is a impedance/loading issue when adapting MN3207/3007 chips to this circuit? They just don't have the voicing of the original and are significantly duller when played side by side.


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## mhammer (Nov 30, 2007)

Since the goal was to reproduce the EM in a smaller package, I didn't expect it to sound either different from, or better than, the original. That's not a criticism of any sort. To my ears, through my system, the EHX original has more top end than the Retro-Sonic, but I am always reticent to chalk anything up to a single example of any pedal. Capacitor values can vary so much within the same nominal value., so a single example of a pedal might be brighter or duller than its production-mates.

There never was a two-BBD version of the EM. _*HOWEVER*_, the SAD1024 could be configured as 1024 stages in series or two 512-stage sections in parallel (like the MN3010). That may be what you're thinking of. The advantage of running the chip in that configuration is that it can achieve shorter delay times, and complementary sections could be used to cancel clock noise more effectively.

The Panasonic chips differs from the Reticon in a few less audible ways, but really only one significant way. The Reticon clock input pins have 110pf capacitance for the 1024 stages, where the Panasonics have 700pf for the same capacity. Much the way cable capacitance eats up your high end, input capacitance on the clock pins starts to erode and "trianglify" the clock pulse as the clock frequency increases. Eventually, what is supposed to be a crisp pulse and near-instananeous handoff of a sample from one stage to another, starts to turn into "Just a sec...cough cough...okay I'm ready now", and audio quality degrades. This is why the Panasonic datasheet for the MN3007/3207 stipulate maximum clock frequency of 100khz. They assumed that the OEM would also use the complementary MN3101/3102 clock driver chip. That chip provides an elegant, simple, and economical (not to mention space-saving) solution for driving the BBD. BUT IT DOES NOT DO ANYTHING TO COMPENSATE FOR THE CLOCK PIN INPUT CAPACITANCE.

However, in the exact same way that one can use a buffer to drive long long cables without fear of any high-end loss, several companies implemented buffers to drive Panasonic chips well beyond the supposed 100khz limit, to obtain delay times shorter than the 1msec that the Boss BF-2 achieves. I have seen, in person, an MN3007 successfully and safely clocked up to 1.5mhz, with a suitable buffer/driver. The legendary A/DA Flanger, best known for it's ability to sweep into the stratosphere (you know, where the Strats live), started out with Reticon chips and switched to Panasonic, but they included a buffer/driver. The EM uses a CMOS flipflop to directly drive the delay chip, as opposed to a Panasonic clock driver. I doubt it provides enough drive to achieve 1.5mhz, but will likely exceed the 100khz limit by a considerable amount, enough to get those glassy highs, achievable when you're not fighting against low clock frequencies.

And remember that the "dullness" is not inherent to the delay chip itself, but rather to the required lowpass filtering when clocking the delay chip at low rates. The received wisdom is that dramatic flanging really needs to sweep at something at least a 20:1 ratio. So if the shortest delay is 1msec (max clock speed of 100khz), you'd need to sweep out to 20msec (5khz clock frequency) for a dramatic flange sound. And making a potentially 5khz clock pulse tolerably inaudible requires substantial lowpass filtering of the delay signal. If your 20:1 sweep goes from 330usec to 6.6msec and your lowest possible clock frequency is in the 15khz range (above the bandwidth of most guitar speakers), then much less lowpass filtering is needed and the flanger will sound brighter as a result. Examination of both the EM and A/DA schematics shows noticeably less lowpass filtering than found in the BF-2 and similar. This is a big part of why may of the "best" flangers used the SAD-1024. You wouldn't think something as simple as input capacitance would have so may trickle-down effects, but there you go.

As for headroom, bucket brigade chips have precious little to begin with, so changes in supply voltage cannot be expected to have as much impact on the headroom of the delay chip as they do on the op-amps in the rest of the audio path. However, changes to supply voltage CAN have an impact on the nature of the sweep. I have a couple of original Boss BF-1 flangers, that also use a Reticon SAD-1024. The chassis indicates use of 9v, but the service manual indicates using 12V as the supply. It sweeps wider with 12V than 9V.


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## Boogieman (Apr 6, 2009)

My Retro Sonic Flanger also lacks top end (or, is it the other way around: too much low end? ). That was why I used an EQ pedal to boost the high frequencies a bit on the third run of my demo sound clip.

I was shooting for a more jangly metallic swirly sound tone, but can't seem to dial it without getting into the jet flange territory. Not sure if the SAD-1024 chip would make the difference.

That said, I am still happy with how the RS Flanger sounds.


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## mhammer (Nov 30, 2007)

If Tim was obliged to use an MN3207 clone, I seem to recall slightly poorer noise specs in that chip, so perhaps he was obliged to trim off a little more top end to keep clock noise acceptable for pro musicians. But that's speculation on my part.


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## JC103 (Oct 6, 2007)

Thanks for the detailed response Mark. I was hoping you would chime in with some of those details. Correct me if I'm wrong, but the Mistress used the SAD1024 in parallel (512 x 2) to effectively double the flanging delay lines (if we can call it that). I've heard some theories this was done to ensure reliable operation if one of the sides of the SAD1024 failed. Apparently there was a high failure rate at one point during the production run. My point is that you can't run the Panasonic 3007/3207 chips as dual 512 bbds unless you use two running off the same clock (by doubling the clock speed to accommodate the 1024 stages). I don't even know if that is possible. Therefor, there is an element of the original Mistress that is missing. I believe there is some magic in that. As mentioned before, I have 2 Madbean clones running in what we could call a dual mono set up. I try to set them to sound similar and good together. Because my Volante sums the stereo inputs to mono, all the repeats contain the summed flange effect. This sounds more authentic to me when playing and recording my clones than without the Volante. I use to use two DD-2 in dual mono and the sound was different than the summed outputs of the Volante.

What do you make of Dr. Alex's adaptation here:
18V Electric Mistress with reworked LFO & VCO

He has designed a "best of" Mistress circuit, the only caveat is that you need a SAD1024 chip with at least one functional side.


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## mhammer (Nov 30, 2007)

I don't know about running parallel 512-stage lines as a "backup". However, there were two, count 'em, _two_ SAD512 chips. One was an 8-pin chip used in a variety of MXR chorus and flanger pedals, among others, and the other was essentially a 1024D for which only one half was functional. I have no idea whether the other half was avaiable but just not "guaranteed", or was deliberately disabled or something. (Shades of the old days when you could buy "single-sided" diskettes cheap, punch a hole in the corner and make them double-sided.)

The MN3010 was also a dual-512-stage chip like the SAD1024, albeit with the same clock pin capacitance issues as all the other Panasonic chips. It was used in some issues of the A/DA Flanger. My understanding was that running them in parallel accomplished two tasks. First, it halved delay time, and second it offered some possibilities for further cancelling audible clock noise.

The MN3007/3207 (and mythical 3307, which has datasheets published but I've never seen any offered for sale) is 1024 stages, with no division into dual units possible. Actually, let me amend that. They ARE dual 512-stage units, except that one set of 512 stages is interleaved with the other set and can't really be operating separately. Imagine you have a lineup of 512 people, each of whom is doing one task with their left hand and another with their right. The left hand passes something to the right hand of the next person, while the right hand accepts something from the left hand of the person on their other side.

I know that Xvive has reissued an MN3009 clone (256 stages), though I'm not sure if anyone has brought back an MN3004/3204 clone (512 stages).

You will note the near-complete absence of any lowpass filtering of the delay path in that Dr.Alx circuit. And, for reasons I don't quite understand, but assume are related to noise-cancellation, most other EMs use the A output of one set of 512 stages, and the B output of the other set. The DrAlx circuit uses one side of the chip only. I gather this means one can use "reject" 1024s with only one functional side. Of course finding an SAD1024 of anything other than the "fried" variety will be a daunting task, to say the least.


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