EHX - Memory Boy

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Re: EH Memory Boy

Postby culturejam » 25 Mar 2012, 19:36

Peamiller, what frequency did you use for the sine wave?
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Re: EH Memory Boy

Postby Peamiller » 25 Mar 2012, 22:02

I started with 1 kHz, but then I switched it to 500 Hz. I checked the signal at the output jack too, to make sure it was clean, and it basically was (didn't do any frequency analysis w/ Fourier or anything, but basically looked like a sine wave).

The slowest the datasheet prescribes for the clock is 10 kHz, meaning 5 kHz signal bandwidth if you're absolutely hugging that Nyquist limit, so I'd expect the filtering to come in lower so that any clock noise gets attenuated. I think they also run the clock even lower than 10 kHz, because they promise 550 ms, whereas each BL3208 says it will give 102.4 ms at 10 kHz, so four would give 409.2 ms. Slower than 500 Hz gets annoying with the refresh rate on the scope. In fact it's already hard to get really nice triggering.

Also, I was looking at the max delay time, it's pretty much 550 ms. I thnk I just had it a little longer than that beforehand...dunno why. I toyed with the input gain trimpot to IC #4 but couldn't hear much of a difference. Also, self oscillation happens only at the highest settings, it used to happen at ~2:00, and all the way up would get to self oscillation REALLY quickly. Playing with the bias on IC#1, I noticed that as you purposely decrease your headroom, you can get more "gain" into the next one. Maybe they set the feedback to be more sensitive by purposely slightly misbiasing each BBD IC, like #1 and #3 too close to max, #2 and #4 too close to min, so you don't completely misbias it but it's easier to reach some sort of saturation. Also, it does seem like the modulation is as crazy, but maybe it's just a little inconsistent for different delay times and mod speeds.

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Re: EH Memory Boy

Postby allesz » 26 Mar 2012, 13:55

I don't like this pedal, I had it and sold it because:
- the volume boost when engaged is too much (I lowered it with the internal trim pot but a change in volume, and tone too, was undeniable, and with some amps and/or effects it gave too much problems)
- the delay time is too short (but it is just me of course)
- I hate the 9,6 V power supply (and the fact that universal power supplies gets less "universal"), come on EH isn't it beautifull to work with some standards? Or you think that people will make pedalboards with only Eh pedals this way?

Anyway I found a way to bypass the supply power requirements and to get some longer echo: supply the unit from the battery plug with a standard 9V supply. In this case the unit will work properly with whatever psu and the delay will be a little bit longer.
Just, since I don't know if they put polarity protection on the battery plug, watch out for the polarity.... bzzzzt!
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Re: EH Memory Boy

Postby Hides-His-Eyes » 26 Mar 2012, 14:19

9.6V IS a standard power supply. All the big switched mode types (powerall, diago and onespot) give a fairly solid 9.6V at any draw. What power supply did you have a problem with?
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Re: EH Memory Boy

Postby allesz » 26 Mar 2012, 18:02

I used an ibanez adaptor (quite old, but it always worked great, except the memory boy). I mesured the output and it was actually a little bit more than 9 V (9,5 - 9,8?) 500mA, but it did not work with the EH :scratch: .
A friend of mine (who owns both a memory boy and a memory toy) reports the same problema and he says that, even if the pedal works with different psu, they will sound worst.
I did not measure the V out of the EH psu, can it be a little higher than 9,6V?

I really don't whant to talk too bad of the memory boy (but maybe I did it :mrgreen: ): it can be agreat pedal for crazy sounds and really short echoes.
Since my pedalboard is usually made of just a delay and an overdrive/distortion I need a different kind of delay. I stick with my ad9 reissue and I am happy (ok, no modulation, but at least it sounds good); the delay time is not very long too, but I tweaked an internal pot to get little longer repeat time.

Basically I just wanted to report the fact that if you feed the EH by the battery plug you can get slightly longer delays.....
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Re: EH Memory Boy

Postby Peamiller » 26 Mar 2012, 18:53

You can get longer delays, but as their manual says, then you should get a solid 3-4 hours of use out of it :( . Also, if you use an expression pedal to control delay time, you can get some nasty, massively long, aliased-to-death delays out of it. The delay knob is supposed to set the max delay time, but with the pedal in, the knob's values are completely changed, so you have to set it really low for the max expression pedal setting to give you longer, but not ridiculous delays. Of course, this means you have to get an expression pedal. I finally did after seeing that I had several pedals that could use one, although I don't usually use it on the memory boy. It's cooler to adjust the modulation rate with it anyway, I think. Adjusting feedback would have been a nice one too. Oh well I guess that's what the deluxe memory boy's for.

That power supply problem is really odd. I can't imagine why it wouldn't at least work at around 9V. Precariously biased? Current draw too much? Just doesn't seem right.
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Re: EH Memory Boy

Postby culturejam » 26 Mar 2012, 19:22

I'm using mine with a RadioShack power supply (9v @ 1000mA max), and sounds just like it does when hooked up to a Dunlop Brick or a PowerAll. :scratch:
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