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Howard DavisMemberQuote:electricsky, please bear in mind that while Mr Davis designed the deluxe memory man he does not work for EHX anymore, and he has never (as far as I’m aware) worked in the advertising department, so your demands for “i just want what i paid for” should not be directed at him but to EHX via their email. (if you so wish) Mr Davis does independent repairs and upgrades on some EHX pedals and will offer them to you as service if you wish to use them, but clearly he is not responsible for warranty repairs, or customer dissatisfaction with any EHX products, those should be taken up with your dealer or EHX directly. I’m just making this clear as it seems you might be thinking otherwise.
… that said, Howard is a valued member of this forum and I’m sure he will give you honest advise and help in anyway he can.
Thank you for this response on my behalf.
There are a few components that determine the maximum delay time in the DMM. The greatest unit-to-unit variations exist in the DELAY control pot, which has a +/-20% tolerance, and the clock chip itself. While the present circuit configuration is vulnerable to delay time variations, it has the advantage of being able to produce the beautifully liquid-sounding chorus the DMM is known for. I can extend the delay time to as much as a second, but above 650 msec or so noticeable aliasing distortion occurs, and above 750 msec or so most people find it intolerable.Howard DavisMemberIt is NOT a trimpot problem. I designed this pedal, and I know. It is due to component tolerances and other production issues. Do not tamper with the trimpots. I do a mod that extends the delay even beyond 550 msec., but sorry, I cannot do it for free.
Guitar pedal design engineering, repairs, and custom mods:
http://howard.davis2.home.att.net/Howard DavisMemberIn general, the LED is just a rough indicator of signal level.
If the sound is not distorted to an objectionable degree, no problem exists.Howard Davis, EE
Designer of the Stereo Polychorus and Deluxe Memory Man
Guitar pedal design engineering, repairs, and custom mods:
http://howard.davis2.home.att.net/Howard DavisMemberIt needs repair – it may have a bad IC or delay chip.
I can fix it, but please don’t send it before January.
See my website for details – http://howard.davis2.home.att.net/Howard Davis, EE
Guitar pedal design engineering, repairs, and custom modsHoward DavisMemberI do a mod that completely eliminates this common noise problem. Right now though I’m swamped with engineering work, so doing repairs and mods has to be put aside for the time being. Please get back to me in about three weeks.
Guitar pedal design engineering, repairs, and custom mods:
http://howard.davis2.home.att.net/
Email: howard.davis2@att.netNovember 24, 2009 at 7:39 pm in reply to: trimpot calibration for Stereo Polychorus (reissue) #104184Howard DavisMemberQuote:Is there a reason why trim pots aren’t explained in the manual already? They usually are if a pedal has them.Trimpots are for adjustment by a qualified service tech only. To encourage anyone else to tamper with them is to encourage people misaligning or even damaging their pedals. As far as I know, there are no service manuals issued for EH pedals.
November 23, 2009 at 5:53 pm in reply to: trimpot calibration for Stereo Polychorus (reissue) #104118Howard DavisMemberQuote:So, is it possible to adjust the output volume from any of the trim pots or not? Simple answer would be nice.Yes, but there is more than one trimpot that affects output level.
November 20, 2009 at 6:35 pm in reply to: trimpot calibration for Stereo Polychorus (reissue) #103989Howard DavisMemberThe trimpot alignment of a pedal of this complexity should not be undertaken by anyone that is not an experienced technician. You need an oscilloscope, an audio signal generator, a diagram showing the locations of the trimpots and their functions,and the proper procedure. Without all these things, you will probably just worsen the misalignment.
Howard Davis, EE – Designer of the Stereo Polychorus
Guitar pedal design engineering, repairs, and custom mods:
http://howard.davis2.home.att.net/Howard DavisMemberIt may just need a trimpot alignment, which I can do.
Guitar pedal design engineering, repairs, and custom mods:
http://howard.davis2.home.att.net/
Email: howard.davis2@att.netHoward DavisMemberI originally designed the Deluxe Memory Man for a 550 msec. maximum delay. Some units, due to component tolerances and other manufacturing variables, do not have this long a delay time. Due to variances in the factory alignment of the trimpots and the results of rough handling on alignment, some units have cleaner repeats and more headroom than others do. All these problems can be corrected through the proper alignment and modifications that I offer. You can get at least 650 msec of maximum delay time before distortion is noticeably increased at the longest delay settings.
For more information, see my website: http://howard.davis2.home.att.net/
For a list of my Memory Man mods, please email me at howard.davis2@att.net
I DO NOT WORK ON digital pedals such as the “hazarai” model (not my design) or those like the XO models made with surface-mount components.
Guitar pedal design engineering, repairs, and custom mods:
http://howard.davis2.home.att.net/Howard DavisMemberThe most common cause of clock noise is misalignment, and 9 times out of 10 doing a complete trimpot alignment using the proper lab equipment and procedure will eliminate it. Some models, due to PC board layout and lead dress, have a low level of this noise that cannot be completely eliminated. It is usually above 5 KHz or so in frequency, and there is very little if any guitar signal at or above this frequency, so the use of a filter or equalizer that cuts frequencies above 4KHz or so can eliminate it without degrading guitar tone.
Guitar pedal design engineering, repairs, and custom mods:
http://howard.davis2.home.att.net/Howard DavisMemberHi Muffit,
As the resistors you added didn’t reduce the pop, you should remove them – they are unnecessarily loading the input and output, although if they are above 2.2M or so the loading effect is negligible.
It does sound like you have a problem with the pedal. If you want to send it to me for repair, please email me at howard.davis2@att.net.
Guitar pedal design engineering, repairs, and custom mods:
http://howard.davis2.home.att.net/Howard DavisMemberFootswitch pop has several possible causes, and sometimes is not internal to the pedal at all but is caused by DC leakage or other problems with the amp or another pedal. Installing pulldown resistors will not always help, and properly designed pedals already have them. When you have alot of gain following the switch, as in the Big Muff, the pop is amplified and can be intolerably loud. Whatever the cause, if it is internal to the pedal, I can fix it.
Guitar pedal design engineering, repairs, and custom mods:
http://howard.davis2.home.att.net/Howard DavisMemberHi Scott,
I DID reply to your previous emails, and I sent another reply today to the email I received from you today. Have you been missing emails from anyone else? If you do not receive today’s replay from me, please let me know.
Yes, I can do all the mods you want. Let me know which specific model of Deluxe Electric Mistress you have, as some of the mods are not necessary on some models.
Guitar pedal design engineering, repairs, and custom mods:
http://howard.davis2.home.att.net/Howard DavisMemberI’ve found Small Bear Electronics a good source for parts for old EH pedals.
Guitar pedal design engineering, repairs, and custom mods:
http://howard.davis2.home.att.net/ -
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