EM3207 (v1.1) - MN3207 based EHX Electric Mistress (9V) clone

[oldschoolanalog]

On a somewhat related note...
The A/DA Flanger (the real one; not one of the clones) never used the 4049 buffer in any of it's incarnations (SAD1024 or MN3010). As far as I'm concerned; being an owner of one; it is still the benchmark/standard of what a guitar flanger should be. And I have loads of other units to compare it to. Clones & originals. All sorts of makes & models. I think Dave Tarnowski knew exactly what he was doing; not buffering the the clocks. And yes, I realize it is a 512 stage device.
And... With all due respect, the BF2 is a GPS device (Genuine Piece of S#!t [OK, it is durable ]). If you're comparing anything you design to it you should go back to the drawing board & do some more serious R&D. To make a BF2 sound alike (or a "bit better") is a waste of time & resources, IMHO. An MXR 117 clone is a MUCH better choice to clone & mod to extend the sweep ratio.
My 2 cents.
When I get done w/all my court appearances (child support, divorce), I'll get with it & do some serious R&D and compare notes with Tomas and the gang.
Peace y'all.

PS: @Mark Hammer: If you finish your Anderton HF&C; I'll move this to the front of my bench and finish it ASAP:

http://i175.photobucket.com/albums/w121/oldschoolanalog/DSC01402.jpg

[12Bass]

Would be interesting to compare the A/DA with and without the clock buffer.  From everything I've read, the buffer should offer an improvement at the highest clock rates, so I'm unsure how/why an unbuffered design might sound "better". 

FWIW, when I was calibrating my A/DA clone, I played around with the highest clock, setting it to sweep into the cymbals on rock recordings.  It sounded cool sweeping way up there at the time, but I found those super short delay times were practically inaudible with guitar/bass, so I ended up lowering the maximum clock rate to a more usable range.

Definitely curious about the Anderton design.  Some serious thought went into that one....

[Govmnt_Lacky]

And... With all due respect, the BF2 is a GPS device (Genuine Piece of S#!t [OK, it is durable ]). If you're comparing anything you design to it you should go back to the drawing board & do some more serious R&D. To make a BF2 sound alike (or a "bit better") is a waste of time & resources, IMHO. An MXR 117 clone is a MUCH better choice to clone & mod to extend the sweep ratio.
My 2 cents.

I agree about the "quality" of the devices that you are comparing HOWEVER, when we get to reality and see that you can build an entire pedal (i.e. BF-2, FL9, etc.) utilizing the 3207 for the same price as one IC (SAD1024) for the A/DA or M117 then I can see why most people would go that direction.
Now, being someone who has cloned both the FL9 and the M117... I can say hands down that the M117 is absolutely a better flanger in all respects BUT, for the price.. the FL9 is pretty decent as well.

Just my 2 cents 

[oldschoolanalog]

You get what you pay for.
"No free lunch."
My $1 statement for the day.
@Govmnt_Lacky: Need quality BBD's (name your flavor/any colour you like)? Still have those Germs? PM me .
edit: just saw; too late!

[Thomeeque]

 Sorry, just briefly for now, I need to pack for my vacation and go to sleep

The 4049 buffer in your circuit appears to be very similar to the one used in the A/DA flanger clone.

Same, actually

 From what I recall in earlier threads, measured performance was worse when using three inverter stages (like Ultra Flanger).

OK, thanks!

 Even with a 4049 buffered SAD1024, IIRC, there's a roughly 2dB delta in gain between the shortest and longest delay settings; MN-series may be somewhat worse (or perhaps better, if your graph indicates less than 0.4 dB and not 0.4 V difference).

Gain on that graph is just absolute U_OUT/U_IN ratio, not even recalculated to decibels (no dB, no V )

In dB it looks like this:



Unfortunately I did not measure it above 2MHz yet, it will be probably somewhere at -2dB at 2.7MHz (I don't plan to go above 2.6MHz, 2x1280kHz is what I need max ).

OK, 4~5dB drop is far from perfect, but even if it would not be possible to make it better, I could live with that..

Judging by the samples, the MN3207 EM is sweeping higher than a BF-2 can.

EM3207's sweep range at those samples is practically same as DEM15's already (cca 55kHz ~ 2.4MHz = 0.21ms ~ 9.3ms)..

More later, cheers, T.

[12Bass]

John Roberts, who designed many BBD circuits in the 1970s,  offered some suggestions in this post:  http://www.gearslutz.com/board/6693261-post27.html

[ORK]

John Roberts, who designed many BBD circuits in the 1970s,  offered some suggestions in this post:  http://www.gearslutz.com/board/6693261-post27.html

Your J. Roberts there talks about Craig.Anderton as a "dead man"

(RIP)

Tell you what: C.A. has been active this very morning on Harmony Central where he is the admin.  Elsewhere recently: http://twitter.com/#!/Craig_Anderton

[12Bass]

My guess is that Mr. Roberts had Craig Anderton confused with Stephen St. Croix, who designed the Marshall Time Modulator.  Anyway, from what I gather, John Roberts has pretty serious technical chops. 

[12Bass]

Just made some rough measurements comparing my A/DA clone with the Classic Flanger VST plugin which has a digital readout of delay time.  For comparison, I turned off modulation and set the VST flanger for high feedback, then played white noise and dialed the A/DA to match the pitch.  At the shortest delay, it is just slightly less than 0.2 ms, about half of the original A/DA specification of 0.4 ms.  So, my flanger sweeps about an octave higher.  It will go even higher than that, but I found that the volume drop was more noticeable, plus there's not much left up there to flange.   I set the low end for 13 ms, as I found that it wasn't musical sounding going much longer than that. 

With a 512-stage BBD line, giving 256 samples, the maximum clock rate was calculated to be 1.28 Mhz, while the minimum is 19.7 kHz.  However, because the two sections are used in parallel-multiplex, the effective sampling rate is actually twice that, as there are double the number of samples per clock cycle (2 x 256 = 512).  So, the maximum effective sampling rate is 2.56 Mhz, while the minimum is 39.4 kHz.  Note that the latter clock rates would be the same as a 1024-stage BBD, which also provides 512 samples.  I'm somewhat curious to test the impact of the 4049 buffer, to see how it affects higher clock rates, though perhaps it is best to leave it alone, now that everything is working so nicely.

As for the BF-2, it is only rated for 1 ms minimum... which is about where things start to sound interesting.  A flanger with a minimum delay of 0.2 ms would sweep over two octaves higher.  One of my favorite flanging sounds is sweeping up through the 0.4 to 1 ms region and back down to the lower ranges, which can have a cool "screaming" effect when a moderate amount of regeneration is added.  The BF-2 is incapable of reproducing this effect.

[Ben N]

Note that the Boss BF-2 doesn't have a sweep range much wider than what Tomas was disappointed to see in V1.1.  And from the little I can tell, the BF-2 has a straightforward triangular sweep.  So even if this 3207-based EM does not eventually manage to attain the grand sweeps of its 1024-based ancestor, building it will still probably get you a reasonable BF-2 workalike that  sounds good.

No offense, but a BF-2 is to an EM as Hamburger Helper is to filet mignon (IMHO).

[12Bass]

Comments from Mike Irwin on the 4049 buffer:

http://archive.ampage.org/threads/4/fxgd/104868/ADA_Flanger_calibration-4.html

"Hi Dave, 
Thanks for putting those scope shots up! Nice to see. The observed rise/fall times for the SAD are shorter, as expected, due to less loading of the 4047 (assuming a 4047 is in the circuit...I have not seen an SAD-based A/DA schematic). The 4049 buffer in my modified clone reduces the rise/fall times considerably so they are within spec for the SAD. To my ears, there is a noticeable inprovement in the sound - better clarity - at the normal delay settings. I have clocked the SAD at up to 2.5 Mhz (meaning the internal osc of the 4047 is running at 5 MHz) which gives very short delays - without the 4049 the clock signal is very rounded with decreased amplitude. The MN3101/MN3102 clock chips are nice to use to drive any BBD as they have substantial drive ability compared to the more typical CD4013B approach. Now for the big question: is there much of a sonic difference between the two units (in-spec MN3010 vs. out-of-spec SAD)?"

http://www.diystompboxes.com/smfforum/index.php?topic=72329.msg585416;topicseen#msg585416

"I would have liked to use the 4049 inverters set up as two groups of
three paralleled inverters - but the 4047 is not able to drive the
combined gate input capacitance very well... so the technique shown has
been used as a compromise to preserve good rise/fall times."

[oldschoolanalog]

No offense, but a BF-2 is to an EM as Hamburger Helper is to filet mignon (IMHO).

But it's DURABLE man! (See ill my ill natured/opinionated post above )
OK, OK. No more BS, uh, I mean BF2 bashing.
Now the BOSS BF1 (Big Blue). There's a nice (guitar) flanger!

@12Bass: Mr. Roberts summed it up best in his last sentence. If it sounds good, it is good... Nice link BTW; thanks!

[Mark Hammer]

No offense, but a BF-2 is to an EM as Hamburger Helper is to filet mignon (IMHO).

But it's DURABLE man! (See ill my ill natured/opinionated post above )
OK, OK. No more BS, uh, I mean BF2 bashing.
Now the BOSS BF1 (Big Blue). There's a nice (guitar) flanger!

@12Bass: Mr. Roberts summed it up best in his last sentence. If it sounds good, it is good... Nice link BTW; thanks!

I accept all your comments at face value.  Whatever shortcomings it has in the way of providing dramatic inspiring flanging, the fact is that flangers cover a lot of ground, much of which isn't terribly different from what a chorus does - just shifted over a bit - and it can do that part just fine.  Admittedly, you wouldn't marry someone just because they know how to dry dishes, switch the clothes over from the washer to the dryer, and bring the garbage out to the curb.  But you do have to accept that the banal tasks are an important part of what makes relationships work, and in this instance the BF-2 handles the banal tasks admirably.  So, while I eagerly await Tomas' explorations for how to bring out the sultry in this build, I'm fine with what's there....for now.

[oldschoolanalog]

I agree w/you Mark. I just don't feel it's justified to recreate (or thereabouts/a bit "better") the sound of something that can be bought in a pawnshop for ~$30 (US). Less than the cost of parts for doing a DIY flanger. And a heck of alot less time (unless one values their time as zero).
Old saying: "If you are wasting time, you are wasting money. If you are wasting money, you are wasting my time."
Just having a bit of fun also.

[Thomeeque]

John Roberts, who designed many BBD circuits in the 1970s,  offered some suggestions in this post:  http://www.gearslutz.com/board/6693261-post27.html

Definitely interesting post, thanks, I'll probably read whole thread.

But when talks about possibility to improve linearity by more sophisticated treatment of BBD outputs (e.g. by using buffer), he probably does not mean straightening of the GAIN-f_CLOCK characteristic. It's IMO about lower distortion of passing signal.

"..The MN3101/MN3102 clock chips are nice to use to drive any BBD as they have substantial drive ability compared to the more typical CD4013B approach.."

Hmm, I wonder how this is meant. When I briefly looked into MN3101/MN3102 specs, it does not look they would even think about frequencies higher than 1MHz..

"I would have liked to use the 4049 inverters set up as two groups of
three paralleled inverters - but the 4047 is not able to drive the
combined gate input capacitance very well... so the technique shown has
been used as a compromise to preserve good rise/fall times."

Oh, so that's why.. Would 4013's outputs behave same as 4047's (be not able to drive 3 parallel gate inputs capacitance very well), did somebody already try? According to specs both 4047 and 4013 outputs are buffered (I'm kinda surprised, that 3 parallel gate inputs can give hard times to buffered output actually.. but I have very limited knowledge about gates).

Google returns lot of hits when searching for "clock buffer", like this one: Inexpensive High-Speed Amplifiers Make Flexible Clock Buffers, but I'm not sure I want to go that deep.. we'll see, first (when I'm back from vacation) I'll measure EM3207's full GAIN-f_CLOCK characteristic and maybe try 2x3 buffer yet.

Now the BOSS BF1 (Big Blue). There's a nice (guitar) flanger!

I did not know BF1, impressive monster

Cheers, T.

[Eduard_Solderingironhands]

Hi,

although new here, I'm building DIY stompboxes for more than 20 years. I planned to build an Electric Mistress clone some years ago but forgot to buy the SAD1024. I wanted to finish the project now and - uups- no more SAD1024. I found this thread and the MN3207 looks like a promising alternate.
My question is, if the clock is the sole problem, why not use a microcontroller? These are cheap (at least as cheap as the parts for the LFO if you don't consider the programmer) and run up to 16 MHz, so a clock below 2 MHz should be no challenge. I can offer to design a layout and write the C-code for such a application if you give me the specs. Interested?

Best wishes

Ralf

[oldschoolanalog]

@Ralf: Check out the MN3007 EM here. Tried & verified. Lots of successful builds and documentation as well.

[Thomeeque]

Hi,

although new here, I'm building DIY stompboxes for more than 20 years. I planned to build an Electric Mistress clone some years ago but forgot to buy the SAD1024. I wanted to finish the project now and - uups- no more SAD1024. I found this thread and the MN3207 looks like a promising alternate.
My question is, if the clock is the sole problem, why not use a microcontroller? These are cheap (at least as cheap as the parts for the LFO if you don't consider the programmer) and run up to 16 MHz, so a clock below 2 MHz should be no challenge. I can offer to design a layout and write the C-code for such a application if you give me the specs. Interested?

Best wishes

Ralf

Hi Ralf, welcome! I'm definitely interested, but little sceptical too. Is there a way how to generate clock sweeping from 58 to 2560kHz fluently enough to not make audible "steps" in the sweep? Sweep rate is set usually very slow (seconds), you know..

If yes, specification is relatively simple:

Virtual VCO must follow this characteristic:



with frequency doubled.

Virtual LFO (would you implement LFO part as well? It would IMO make sense) must generate triangles with V_MIN = 1.26V and V_MAX = ?? (minimal range)* to 10.31V (maximal range). Volts are here of course virtual as well, it's just to make connection with characteristic above.

Mathematically it's easier to convert frequency to period (as you can see on the "delay" characteristic, period-V_CTRL characteristic is practically linear), then can be VCO and LFO definition merged into one simple picture:



Does it make sense? I can give you more details, but this should be enough for initial thoughts, I'd say..

T.

* I'm not sure about this value for minimal range, wild guess is cca 2.5V, I can measure it later (but you could go from V_MIN to make RANGE control more versatile then original EMs have).

[Thomeeque]

@Ralf: Check out the MN3007 EM here. Tried & verified. Lots of successful builds and documentation as well.

Just small note here:

If you like 9V EM with MN3007 retrofit, you should like original EM3207 v1.1 (without mods I'm working on now) as well - it should be practically same thing.

Actually, if somebody would care to make some small demo of 9V EM with MN3007 retrofit, it would be just brilliant!!

Cheers, T.

[davidefender]

I worked a lot with uC, most with ATmega.. my opinion is that the LFO can be generated not exactly as needed. If you have to reach that freq, it's quite impossible to generate triangle waves (due to the relative slow frequency of the PWM), but you can *easily* get a square wave from 0 to V+ with that specification (LFO speed and clock speed)...