# Deluxe Memory Man Chip Calibration Questions...



## Guest

I am looking at getting an old big box DMM and I have read about different chips, as well as sending the unit in to the original designer and he calibrates the chips.

What does this mean "calibrate the chips"?

Is this something any pedal tech can do or is it "magic" that only a select few can do?

Which DMM chips are most desireable and is there a sourse to buy one or two and is it feasible to swap those out in a newer DMM?

Any other DMM info would be helpful.


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## neldom

I had an old DMM that needed the work.
Each bucket brigade chip has a couple (i think it was a couple) of associated pots for calibration, I have reasonable pedal experience and equipment (scope, etc.) and it was not something I was able to do myself.
Not a wealth of information out there on it for a process either, that I could find.
Howard was quick for turnaround and he offers some good mods as well, though it's not entirely cheap so if you know the pedal needs work make sure you're not paying a lot for it.
The chips are not swappable either, the newer ones have less chips in them and they are not interchangeable with the old ones.

They do sound great though, distinct saturation, modulation sounds, wonderful on the verge of oscillation sounds too.
Really a unique sounding delay.


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## Clean Channel

The calibration takes the right equipment. You're gonna need to get someone to do it, so why not have Howard Davis (designer of the DMM) do the work? Eventually he'll have to retire from doing it, so in the meantime kinda neat to be able to access his specific expertise.

The most sought after chips are the mn3005 chips. They're hard to find/expensive on their own, and there are a lot fakes/mislabeled ones, so buy with caution.

There are a lot of old pedals made with mn3005 chips, and sometimes you can score a few by getting a good deal on a piece of equipment.

Every once in a while someone will be selling a Yamaha E1010 rack unit for next to nothing. Those actually have four mn3005 chips in them (yeah, I have one), and are pretty cool sounding to boot.


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## mhammer

It doesn't necessarily require equipment other than ears

There are usually 2 and sometimes 3 adjustments to make, depending on the DMM issue, and pedal design.

EVERY bucket-brigade chip requires the audio signal to march in on a DC voltage. Look up the schematic of just about any analog delay, chorus, or flanger, and you'll see a trimpot that feeds a DC voltage to the input pin of the chip. On occasion the DC "bias" will be fed to the chip before the BBD, but this is less common than having the bias trimpot feed the BBD input directly. The DC bias can be adjusted by ear in the following manner:

1) Use the cleanest input signal you can, and set up the listening amp for the cleanest sound possible.
2) Set the DMM's controls for the most delay signal in the mix. A medium delay time is good (not toolong or short), and a little bit of Feedback/repeats helps. What you are aiming for is the ability to hear a delay signal if there is one present.
3) There is a sweet spot when it comes to DC bias. Less DC than is required and you won't hear any delay at all. Too much DC and you also won't hear delay. As you rotate the trimpot fro one extreme to the other, you will pass through a zone where there is no delay, to one where there is audible but very distorted delay, to an optimal zone where the delay is strong and clear, back to distorted delay, and finally no delay...again. You will NOT destroy the chip by going to one extreme of the trimpot or the other. You will simply lose or regain the delay signal, so tweak away.

A second trimot is often used to balance the two outputs of the BBD. These chips use a clock to step them through their paces, and have two channels internally. One channel responds to the "tick" of the clock, and the other carries out the same action when the clock goes "tock". The two outputs are sort of interlaced to provide a (near) continuous signal. The audibility of the clock, however, is achieved when the two outputs are perfectly balanced for output level. Some manufacturers will simply use a pair of equal-value resistors to do this, while others will use a trimpot and adjust for least clock whine.

To do this without a scope, one would set the delay for the longest time, and most feedback, to make the clock whine most audible. No audio input signal is required, since you are listening for sound that the circuit itself produces. The trimpot would then be adjusted to the point where the whine is least audible.

Finally, depending on the issue/model, EHX sometimes strung several delay chips in series. Since they can each lose a teensy bit of signal, EHX would often stick a "gain recovery" stage between them, with an additional trimpot to set the level such that the signal level going_ into _the delay chip was the same as that coming _from_ the delay chip. This can be a little trickier to set in the absence of a meter or scope, since it is difficult to assess by ear when listening to the final output of _several_ delay chips (i.e., which one is too loud/soft?).

All of that said, it CAN be done by ear, with 98% accuracy, without compromising any of the circuitry. Just make sure to mark off where the trimpots started out so that you can return things to where they were if you failed to make any improvements.


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## keto

Everyone who reads that ^ should like that post! Another fantastic share from the wealth of Mark's encyclopedic knowledge base. :bow: :bow: :bow:


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## mhammer

Thanks, Keto. Much appreciated.

I will say that one of the reasons why pedals like the DMM, or better yet, the 24-trimpot Maxon AD-999 (made when 1024-stage MN3007s were still available but 4096-stage MN3005s were long gone), can be made and sold without costing $800+ from Musician's Friend, is because being familiar with it, and having a scope, makes the job simpler and faster. The folks at the EHX factory certainly didn't waste a full hour tweaking a DMM to perfection. They had a setup, went bippity-boppity-boo, and moved on to the next one. You CAN do a pretty decent job yourself, without having to ship a pedal away, pay for all the to-ing and fro-ing, and waiting. In Richard's (player99) case, he lives out of town, so there is nuisance involved. Not drive-from-Yellowknife-to-Edmonton nuisance, but nuisance all the same, and enough nuisance that the time it would take to get a decent sound would be less than what it takes to drive from where he lives into town to bring it to a guy with a bench and scope.

Just keep yer damn soldering gun away from it, Richard!!! (in-joke, there)


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## 335Bob

I had Howard Davis tweak my DMM. It came back sounding great. However, there were issues with UPS dinging me with charges/customs brokerage fees. A mess not worth my time to untangle, so I just paid the fees. It was not cheap and there was some confusion on UPS' part about who was to be charged and Mr. Davis was not a patient man, even though I took care of the situation promptly. So, all in all, the DMM sounds great, a keeper on my board. Although, I could've probably bought a high-end boutique delay for the same money.
Live and learn...


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## Guest

Thanks Mark!

One interesting option is you can send a DMM to the original designer, Howard Davis for calibration. He also offers mods.

One of the things that require calibration is it will not handle a signal very well without distorting. Another is extending the delay time to 550 ms from as low as 300 ms.

Are these addressed in your posts Mark? I would rather tweak it myself (when I get one) than mail it off.


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## Guest

335Bob said:


> I had Howard Davis tweak my DMM. It came back sounding great. However, there were issues with UPS dinging me with charges/customs brokerage fees. A mess not worth my time to untangle, so I just paid the fees. It was not cheap and there was some confusion on UPS' part about who was to be charged and Mr. Davis was not a patient man, even though I took care of the situation promptly. So, all in all, the DMM sounds great, a keeper on my board. Although, I could've probably bought a high-end boutique delay for the same money.
> Live and learn...


It is wise to never send anything by UPS because they charge those high brokerage fees. If you would have sent it by USPS and Canada post there is usually no charge. If there is, the maximum is $5.

Another caveat with Mr. Davis is if you don't pay for the repair right away, which you should, he has this policy:

"STORAGE CHARGES AND UNCLAIMED UNITS:
Please pay promptly when billed. Should payment not be received within one month of the billing date, a STORAGE CHARGE of $2.00 per week will begin to accrue. SHOULD A BILL REMAIN UNPAID THREE MONTHS FROM THE BILLING DATE, the unit(s) will be considered ABANDONED PROPERTY and WILL BE SOLD or DISASSEMBLED FOR THE PARTS, unless previously agreed otherwise with the sender."


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## 335Bob

Player99 said:


> It is wise to never send anything by UPS because they charge those high brokerage fees. If you would have sent it by USPS and Canada post there is usually no charge. If there is, the maximum is $5.
> 
> Another caveat with Mr. Davis is if you don't pay for the repair right away, which you should, he has this policy:
> 
> "STORAGE CHARGES AND UNCLAIMED UNITS:
> Please pay promptly when billed. Should payment not be received within one month of the billing date, a STORAGE CHARGE of $2.00 per week will begin to accrue. SHOULD A BILL REMAIN UNPAID THREE MONTHS FROM THE BILLING DATE, the unit(s) will be considered ABANDONED PROPERTY and WILL BE SOLD or DISASSEMBLED FOR THE PARTS, unless previously agreed otherwise with the sender."


The only reason why I shipped UPS was that I specifically asked if I would be charged customs/brokerage fees. As this was not a purchase but a repair on a used item. I was assured that there would not be any extra charge beyond shipping...well, that's not what happened and like I said, I did not have the time to spend to unravel their mess up which they probably count on. So, UPS lost a customer....


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## Guest

That sucks... What were the brokerage fees?

How  did you pay Howard? He says no PayPal....

Did you get any mods done? What did you get done? Can you tell me what it cost?

Thanks


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## mhammer

Player99 said:


> Thanks Mark!
> 
> One interesting option is you can send a DMM to the original designer, Howard Davis for calibration. He also offers mods.
> 
> One of the things that require calibration is it will not handle a signal very well without distorting. Another is extending the delay time to 550 ms from as low as 300 ms.
> 
> Are these addressed in your posts Mark? I would rather tweak it myself (when I get one) than mail it off.


If you wanted to come by on the weekend, Richard, or some future weekend, we could do it. Extending the delay time is a little more involved than tweaking a trimpot in most cases. The filtering usually needs to be changed to accommodate a slowing of the BBD clock (that will make it more audible and objectionable in the absence of such filtering).

If you pop me a gutshot, or refer me to an on-line gutshot of a unit identical to yours, I can probably find out what needs to be done, and hopefully have a schematic.

Two VERY important questions, though:

1) Does the unit have a 570 or 571 chip on-board? This is the compander, used for both noise reduction and keeping the delay chips safely within their signal-handling limits.

2) What delay chips does it have/use, and how many are there? These could be MN3005, SAD1024, or other MN-type.

All of that info will determine how involved and feasible this is.


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## Guest

mhammer said:


> If you wanted to come by on the weekend, Richard, or some future weekend, we could do it. Extending the delay time is a little more involved than tweaking a trimpot in most cases. The filtering usually needs to be changed to accommodate a slowing of the BBD clock (that will make it more audible and objectionable in the absence of such filtering).
> 
> If you pop me a gutshot, or refer me to an on-line gutshot of a unit identical to yours, I can probably find out what needs to be done, and hopefully have a schematic.
> 
> Two VERY important questions, though:
> 
> 1) Does the unit have a 570 or 571 chip on-board? This is the compander, used for both noise reduction and keeping the delay chips safely within their signal-handling limits.
> 
> 2) What delay chips does it have/use, and how many are there? These could be MN3005, SAD1024, or other MN-type.
> 
> All of that info will determine how involved and feasible this is.


Thanks Mark,

I am still looking for a unit. I am probably going to get one that has the mn3005 chips. I am not sure about the compander. Is it important?

From the comparison demos I have heard on line the older units with the power cord attached seem to sound better than the wall wart ones from the '90's, but I understand the AC powered units are noisier because the transformer is inside the box close to the circuits.

Since I don't have one yet, any advice you might have before I get one would be appreciated.


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## mhammer

It IS better to keep the transformer outside and away from the audio path.

The compander chip makes a world of difference, especially if you are going to be using any sort of boost before the unit. Pre-compander delays would often have a level control and associated LED so you could set the input level for least distortion and best S/N ratio. But if you step on a boost and change the input signal level, you'd have to re-adjust the sensitivity control, and conceivably eliminate the intended volume boost.

Compander chips turn a much wider range of input levels into something that stays within the perimeter of what the delay chip can handle. It IS possible to step beyond that boundary, even with a compander chip, but much less likely. AFAIK, by the time EHX had switched to MN3005 chips from SAD1024, companders had become de rigeur and widely available, so it is unlikely that you'd need to check for one once you had ascertained it used the 4096-stage chips.

Some folks swear up and down on a stack of bibles that the MN3005 units are better, but I suspect that comes from a misunderstanding of headroom. The MN3205 chips do not have noticeably less headroom than the MN3005 chips (maybe a teensy amount). The latter may _appear _to, to the untrained eye, because they run off 12-15V, and people normally figure higher supply voltage = more headroom. However, where the _op-amps _in the pedal can benefit from a higher supply voltage (i.e., they can swing out to +/-5V without clipping), the _BBD chip _has a much smaller range to operate in, that even a 5V supply satisfies. The wallwart Memory Mans with newer MN32xx chips provide the higher supply voltage to the other parts of the circuit, but drop the 24v or whatever down to +5v for the delay chips themselves. Whatever audible differences in quality may exist likely have more to do with unit-to-unit variation in the filter caps or trimpot settings than the fact that they used this chip or that.


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## Guest

I have read the mn3005 chips are very quiet compared to others, and they have a high something or other at 4000. The mn3008 chips are the same, but with only 2000, so twice as many are needed, and that makes for more calibration. The mn3200 are supposed to be less desirable than the mn30xx chips. I have an old Boss DM3 with the mn3200 and it is not as nice as what I hear the DMMs to be. I understand the DM 2 has the mn3005 chips and is supposed to sound better than the DM3.

Analogman has a big write up about this stuff on his website.


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## Guest

Mark is it possible to make an old '70's unit with the transformer built in run on an external power supply? I have a line on a '70's unit with the 2 pronged ac cord.


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## mhammer

I'm certainly not in any position to either confirm or deny what people hear, or at least think they hear. I just think there is a lot that gets attributed to things like this chip or that that is sometimes a result of the chip, but often a result of something else, and the chip differences are simply pegged as the cause. In many cases, people will take one example each of two pedals, and presume that the unit-to-unit differences they hear will be consistently found between _all_ units of the one issue and _all_ units of the other. To be fair, sometimes they are, but unless one takes a broad sampling of units in each, it is risky to assume that a one-pedal-vs-another-pedal comparison has positively identified a consistent difference and the reason/s for it.

The MN32xx series were certainly not a cheaper shoddier-made version of the original chips. Panasonic had absolutely no reason to slack off on their quality. The primary functional difference between the 3200 and 3000 series was that the 3200 could run off a lower supply voltage, which meant that if you were operating from a battery, you could set the bias voltage once (in the manner described earlier), and it would remain valid as the battery aged, much longer than would be the case with the 3000 series, where the bias set with a fresh battery would be off if the battery dropped from 9.6 down to 8.6V.

The 30xx series has a somewhat higher S/N ratio (75db) than the 32xx series (67db), but not the sort of thing that sticks out like a sore thumb once you factor in companders, lowpass filtering, "bias drift"m and op-amp choices. In other words, those specs can be readily overcome by other aspects of design, and do not remain in spite of whatever else you try to do to keep noise in check.

I will also note that the DM-2 uses a 570 compander chip and the schematic notes that the MN3005 chip is "selected: (whatever that means), while the DM-3 schematic from Boss indicates use of a 571 compander chip and gives no indication that the 3205 chips were selected in any manner. (Note: though not dramatically different, the NE570 chip is supposedly a lower noise version than the 571, although I gather the noise differences are increased as supply voltage is increased). So, I'm not running to attribute differences between "any old MN3005" vs "any old MN3205", based on people's experiences with a couple of Boss pedals. I think there is more going on than they realize.


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## mhammer

Player99 said:


> Mark is it possible to make an old '70's unit with the transformer built in run on an external power supply? I have a line on a '70's unit with the 2 pronged ac cord.


Yes, it is possible. Nothing has to be removed from the original unit. At least not enough to harm its resale value. YOu simply take out the power cord, stick an external power jack in the slot where the power cord and grommet used to be, and connect the power jack to where the on-board transformer would normally be connected. Desolder the leads from the onboard transformer, and find yourself a suitable AC wallwart, and you're in business. The onboard circuitry converts the AC to appropriate DC. You should be concerned with EMI from the transformer, but there is nothing to worry about with respect to the rest of the power-conditioning circuitry onboard.

Just because it is "70's" doesn't make it desirable. You will want one with companding and the appropriate chips. Given that the electrolytic capacitors will be 30+ years old, many of them may be dried out and need replacing. Again, easy and cheap to do; it just needs to be _done_.

Would this be a 3, 4, or 5-knob unit?


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## Guest

5 knob.

Here is the info from AM site:

_Deluxe Memory Man info
The Japanese Panasonic MN30XX chips are the best ever made, a little better than the more recent (but also discontinued) Japanese MN32XX chips in the DM3, AD9 etc. and better than the BL32XX Chinese chips. These MN chips are all discontinued, only the Chinese chips are still made. Don't know how much longer EH will be able to make the memory man with the good old Japanese chips but they are still using them now in the XO series small die-cast Deluxe Memory man and they were used in all the classic large box DMM pedals.
3X05 = about 4000 delay stages, 3X08 = 2000 stages, 3X07 = 1000 stages.
In about early 2006 the DMM changed to relay true bypass switching, and four MN3008 chips instead of two MN3005 chips. HOWEVER... this new board has jumpers on it so you can run it on two chips OR four chips. I have seen quite a few of these in 2008 that came with the new (relay) board, but with two MN3005 chips. Very nice.
The DMM has either MN3008 chips (4 * 2000 = 8000 stages), or MN3005 (2 * 4000 = same 8000 stages) for the same delay time.
4000 stages is good for about 300mS at reasonable quality (AD9, AR20DL, etc) or 200mS at high quality (DMM).
1000 stages is more than enough for a chorus (we use new old stock MN3007 chips in our chorus). There were also 512 stage chips used fo chorus and flangers (best for a flanger).
To check if you have the new DMM version with the relay, turn it on and play, so you are hearing the delays (effect on). Then unplug the power from the back of the DMM. If it turns off and you hear your normal guitar sound, then it has a relay. If you hear nothing, then you don't have the relay. You can also tell as the stomp switch only has two wires on it if you have the relay.
EH is probably running very low on the MN3005 chips. Theoretically, the less delay chips you have, each with higher number of memory positions to add up to the same amount of memory, the better the sound. But in reality there is little sound difference between two 3005 chips and four 3008 chips. But there are twice as many calibration points to dial in if you have 4 chips. Some delays have EIGHT CHIPS (ad999?), that must be a nightmare to calibrate... I don't like the AD999 as much as the Ad900 as it has enclosed pots that can't be cleaned or replaced, and a very weird circuit- it sounds almost digital at low delay times. The Maxon AD900 was better to me, a normal analog delay circuit and we can mod those for true bypass and expression pedal control jacks.

late 2008 discovery

The latest DMM pedals I have seen are very interesting, they have been using two MN3005 chips again instead of the four MN3008. Maybe they are using any chips they still have left. The current relay switching board is set up so you can run 2 or 4 delay chips. These pedals would be cheaper to double the delay time on as you just need to change the trace cuts and jumpers, add 2 chips, and calibrate. You can tell which one you have by putting your fingers under the board near the switch and feel if there is a chip in the socket labelled U4 and U5. If a socket is empty, you have the two delay chip version. These MAY sound a little better. They are also easier to calibrate (2 less chips to calibrate) and that may lead to them sounding better as there are less places to mess up calibration. We are offering the double delay time mod in 2010. Email for more info. _


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## Guest

I would power it with the 2 12V spots on my PP2 coupled to give the 24V. I am not sure of the mA required.


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## mhammer

I am not absolutely certain, but the unit may take the 24v input and regulate it down to 12v. If so, and if your PP2 unit has a 12V*DC* output, then you'd be able to power the DMM directly, without requiring a wallwart or fancy-schmancy wiring.

Plain vanilla clock driver circuits for the Panasonic chips are spec'd to handle up to about 8k stages of delay, = 2 MN3005 chips, or 4 MN3008 chips, or 8 MN3007 chips. In theory, one can devise clocks capable of driving more, but the trick is to overcome the capacitance on the clock input pins. You know how a long unbuffered cable eats up high end? Well, the same thing can happen with the input pins on a delay chip. Except in this instance, rather than the clock pulse being a nice crisp square wave, such that there is no discernible gap between the tick pulse and the tock pulse, the clock pulse will have its rising and falling edges rounded off such that you end up with a teensy gap between successive samples (since each pulse doesn't hit max immediately but gradually rises to max voltage, and gradually falls, giving the chip a brief moment before the next "bucket" is passed along).

Each 4096-stage chip has a clock pin input capacitance of 2800pf, such that a pair of them hangs roughly 5600pf on the clock lines. That'll surely round off those square waves, unless you have a buffer circuit to overcome it.

Mike Matthews is reputed to have effectively bought the world's supply of MN3005 chips when he knew it was going to be discontinued, so that he could keep on producing DMM units. This is why, for example, Moogerfooger had to limit production of their analog delay unit. They could have made more, but they'd need access to a bigger supply than Mike made available. And Mike snagged all those chips because of an experience in the early 80's when Japanese manufacturers had persuaded Panasonic to save their supply for domestic producers, choking off EHX. That obstruction was one of the episodes that brought EHX to its knees for a while.

I think Analog Mike is spot in his analysis of potential audible differences between the 4 chip (MN3008) and 2-chip (MN3005) units. More than likely it does have to do with the difficulty of adjusting all those trimpots, as well as the DC blocking caps you have to stick between the successive chips.

I can't speak with authority on whether the Chinese chips are equal to or worse than the older Japanese ones. I assume when Panasonic decided they weren't going to be in the bucket-brigade business anymore, they simply sold off the dies to Beiling. As far as anyone knows, the design is identical, though I suppose there are always potential differences in quality control to be considered. Coolaudio also makes the chips now, for all those Behringer pedals. I'm assuming Behringer has a little tighter control of quality because they have a reputation on the line.


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## analogteletube

Wow, I've been searching online for this info for YEARS! I even emailed Howard Davis, but no luck. Thank you! I ended up just fiddling with the trim pots in my Memory man until I got it sounding good, though I wish I had this info beforehand, I was always scared I might cause permanent damage to the unit. 

I know its probably a long shot to diagnose over an internet forum, but my memory man seems to jump back and fourth between two different delay times/clock wine levels intermittently/spontaneously, and when in the longer delay time/louder wine mode the modulation seems to disappear. If I flip the power switch off and back on it usually jumps back into the shorter/working modulation mode,... maybe a bad capacitor re-charging? Oh, and strangely it seems to happen more often in hot/humid weather, barely ever happens in the winter. It's a 90's reissue, internal transformer, MN3005..., Any help would be greatly appreciated but if not thanks again!


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## Guest

mhammer said:


> I am not absolutely certain, but the unit may take the 24v input and regulate it down to 12v. If so, and if your PP2 unit has a 12V*DC* output, then you'd be able to power the DMM directly, without requiring a wallwart or fancy-schmancy wiring.
> 
> Plain vanilla clock driver circuits for the Panasonic chips are spec'd to handle up to about 8k stages of delay, = 2 MN3005 chips, or 4 MN3008 chips, or 8 MN3007 chips. In theory, one can devise clocks capable of driving more, but the trick is to overcome the capacitance on the clock input pins. You know how a long unbuffered cable eats up high end? Well, the same thing can happen with the input pins on a delay chip. Except in this instance, rather than the clock pulse being a nice crisp square wave, such that there is no discernible gap between the tick pulse and the tock pulse, the clock pulse will have its rising and falling edges rounded off such that you end up with a teensy gap between successive samples (since each pulse doesn't hit max immediately but gradually rises to max voltage, and gradually falls, giving the chip a brief moment before the next "bucket" is passed along).
> 
> Each 4096-stage chip has a clock pin input capacitance of 2800pf, such that a pair of them hangs roughly 5600pf on the clock lines. That'll surely round off those square waves, unless you have a buffer circuit to overcome it.
> 
> Mike Matthews is reputed to have effectively bought the world's supply of MN3005 chips when he knew it was going to be discontinued, so that he could keep on producing DMM units. This is why, for example, Moogerfooger had to limit production of their analog delay unit. They could have made more, but they'd need access to a bigger supply than Mike made available. And Mike snagged all those chips because of an experience in the early 80's when Japanese manufacturers had persuaded Panasonic to save their supply for domestic producers, choking off EHX. That obstruction was one of the episodes that brought EHX to its knees for a while.
> 
> I think Analog Mike is spot in his analysis of potential audible differences between the 4 chip (MN3008) and 2-chip (MN3005) units. More than likely it does have to do with the difficulty of adjusting all those trimpots, as well as the DC blocking caps you have to stick between the successive chips.
> 
> I can't speak with authority on whether the Chinese chips are equal to or worse than the older Japanese ones. I assume when Panasonic decided they weren't going to be in the bucket-brigade business anymore, they simply sold off the dies to Beiling. As far as anyone knows, the design is identical, though I suppose there are always potential differences in quality control to be considered. Coolaudio also makes the chips now, for all those Behringer pedals. *I'm assuming Behringer has a little tighter control of quality because they have a reputation on the line.*


Are you joking about the Behringer? Do you think you could make a Berhinger clone sound as good as the DMM?

What is the better compander chip? My unit has the 571. Is it the more desirable one?

I think the wall wart versions are using a 24v adapter. Would they not just use a 12v if they could?


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## mhammer

Player99 said:


> Are you joking about the Behringer? Do you think you could make a Berhinger clone sound as good as the DMM?
> 
> What is the better compander chip? My unit has the 571. Is it the more desirable one?
> 
> I think the wall wart versions are using a 24v adapter. Would they not just use a 12v if they could?


People are entirely justified in not liking the chassis that the Behringer pedals come in, and they make some questionable chip choices on occasion (my acoustic modeller pedal uses the noisier TL064 instead of a quieter, but more current-hungry, TL074), but the design is the design is the design, and if they use the same design as an older Boss or EHX pedal, why should it _not_ sound as good as them?

The 570-vs-571 differences are apparently not huge and only emerge under certain conditions. I wouldn't worry about it. Neither do most manufacturers.

The regulator circuits provided in the pedals, for turning AC into DC, will always want a greater_ incoming _voltage than they put out. They also have a fairly wide range of acceptable input voltages above that minimum requirement. It is simply easier for EHX to provide one common AC adapter, and just change the part values in the pedal to turn the 24VAC into 18V, 15V, 12V or whatever it uses.


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## Guest

This is the Behringer Vintage Time Machine, a DMM clone:











Gut Shot:


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## mhammer

Yep, that's how they make'em these days. Here's an MXR Carbon Copy.


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## Guest

But the question is... can a Berhinger VTM be tweaked to be identical to an old DMM? I saw one for sale on the net for $50.


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## Guest

Hey Mark, looks like I will be taking you up on your offer to work on a DMM. I am buying one from 1979 that apparently was checked out by a tech and given a 100% thumbs up. It is apparently a little noisier but sounds as good as they can get. Do you have one of those 9v style plug receptors that I can use to change the power to external?

I should have it by middle of next week.

R


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## Guest

I understand it is not difficult to make the pedal true bypass...?

Also another mod is to make the led turn on and off with the switch. I guess it stays on as long as it is powered, not if the effect is on.


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## mhammer

Player99 said:


> But the question is... can a Berhinger VTM be tweaked to be identical to an old DMM? I saw one for sale on the net for $50.


Technically, yes, but you will recall the difficulties we had with that teensy resistor on your Variax. I'm not rushing to do mods on surface-mount pedals (although I did recently get myself a high-power magnification headset from Princess Auto for at least _looking_ at those things)


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## Guest

Here is a DMM thread full of great technical info:

http://www.freestompboxes.org/viewtopic.php?f=1&t=1208


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## mhammer

Thanks. Can't see very much of it because of work filters, but what I can see looks useful. I'll be sure to check it out later this week.


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## Guest

mhammer said:


> Thanks. Can't see very much of it because of work filters, but what I can see looks useful. I'll be sure to check it out later this week.


One thing they talk about is replacing some of the unshielded wire with shielded wire.


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## mhammer

Shielding is always good when you have high frequency clocks and audio living inside the same box.


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## Guest

A schematic? I am not sure if it is good or not... (I could not get it to show up in this forum)

http://www.freeinfosociety.com/electronics/schemview.php?id=381


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## Guest

I got the 1978/79 Deluxe Memory Man today. Sounds really nice. I am used to using a DMM setting on my Strymon Timeline so it is not radically different or hugely better than the TL. It is better though. More musical and organic. The TL is sort of machine like in it's repeats, the DMM is liquidy.

I can't wait to take it all apart and do stuff to it.


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## Guest

Schematics, board layouts, build lists and more:
www.scribd.com/doc/17686325/Analog-Delay-Layout










The parts and values show up on the image on the original site.


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## Mongo

Hi,

I know this is an older thread, but it's exactly what I'm looking for. I just bought a 4x8 Mn3008 model DMM with bypass and the external power supply. It's in need of some TLC and likely calibration. I had to baby the pots with Deoxite to get them to turn freely. They weren't scratchy, just very stiff. There is a noticeable amount of distortion on the repeats and the max delay time is around 400ms. I don't hear any clock whine, but I haven't listened for it specifically. I'm very experienced with a soldering iron, but have a very limited knowledge of audio circuitry. I've studied the schematic for my unit and feel pretty familiar with the layout. I don't have access to a scope (nor would I know what to do with it).

The schematic is visible here:
http://www.scribd.com/doc/125892267/DeluxeMemMan-RI-1

My understanding of the pots are:

*Trims
*
Trim 110KBiasU4MN3008Trim 2100KBiasU5MN3008Trim 3100KGainU3A4558Trim 4100KBiasU6MN3008Trim 5100KBiasU7MN3008Trim 65KBalanceTrim 7100KGainU3B4558


*Knobs
*
P11MLogLevelP210KBlendP310KLogFeedbackP4100k10%DelayP5100KChorus/Vibrato


I think I can follow the process to dial in the bias and hopefully clean up the distortion. I have a very good ear and a steady hand. I've marked the current pot settings. I'm not sure what to reference to evaluate the gain settings, so any help there would be appreciated. I'll also listen for the clock to see if the balance may need to be adjusted. 

I'm really wanting to get the 500-550ms that this unit is capable of. I don't see what could be adjusted to drop the clock timing. My initial thoughts are that the R69 (5.6K) resistor tied to the P4 delay pot could be adjusted to vary the extreme setting of the delay pot feeding U11 (CD4047), but I have no idea what else that would affect. I'm sure the max delay mod is detailed somewhere. I read that the filtering may need to be adjusted to compensate. I'm at a loss as to what that would need to be. I really just want it to work to its potential.

Thanks in advance for all assistance.

Mongo


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