Dirtbag Delay

[nzCdog]

Thanks Josh... what a bummer about the noise. Hope it clears up in the new enclosure, and thanks for telling us so we can avoid the same issue!

[pietro_moog]

hi Madbeans. the prototype is working? do you think we can have it for the end of september?

[gtr2]

Yes, they sound wonderful!!!  I don't know the time frame of the pcb.

Josh

[Scruffie]

The v3205 version will be run at 15v except for the BBDs. I'm doing this to try to emulate some of the headroom of the vintage one....don't know yet how successful it will be.

How are you lowering the BBD voltage? With a shunt diode or regulator?

I assume the design will allow those that want, to use 9V (with adjustments to the compander of course).

[madbean]

I'm working on some last minute stuff to see about merging the different versions into one board like the Aquaboy. I got motivated on this because I worked out a really good layout for the v3205 version that is vertical and regular 6mm resistors instead of 3mm.

Vdd on the v3205 will by a 6-7v zener, I think. I'm still debugging my build.

If it works out, you'd be able to build a 9v (or 15v with a daughter charge pump) version of either MN3005, MN3205 and v3205 and BBD choice depends on a couple of jumpers and maybe a couple minor adjustments. I have to look over the compander stuff again. I remember Dirk had posted some relevant info on FSB. Actually, the comapander is the very thing I need to debug on my v3205 build which is otherwise working.

[Scruffie]

I'm working on some last minute stuff to see about merging the different versions into one board like the Aquaboy. I got motivated on this because I worked out a really good layout for the v3205 version that is vertical and regular 6mm resistors instead of 3mm.

Vdd on the v3205 will by a 6-7v zener, I think. I'm still debugging my build.

If it works out, you'd be able to build a 9v (or 15v with a daughter charge pump) version of either MN3005, MN3205 and v3205 and BBD choice depends on a couple of jumpers and maybe a couple minor adjustments. I have to look over the compander stuff again. I remember Dirk had posted some relevant info on FSB. Actually, the comapander is the very thing I need to debug on my v3205 build which is otherwise working.

A dual purpose 3205/3005 Memory Man with standard resistors (assuming they're not standing up) and onboard pots sounds absolutely brilliant, pretty much the best PCB I could ask for.

Yeah a Zener is what I meant by shunt diode, I found in my experiments an 8V2 to give the best results, although anything from 5-8V should be fine.

You need to adjust the DC bias on the compander for 9V operation... check out the datasheet for the equation but I seem to recall a 47k/47k pair should be right.

How are you dealing with the alternative power requirements? Positive Vs. Negative or have you adapted the 3005 version to take a Positive supply.

[madbean]

Probably just easier to show the draft schematic. The two switches are actually the jumpers underneath the BBDs to select between Vdd and Vgg depending on which chips you are using. D5 is the shunt to the VD supply.

On the compander---the NE570 is rated up to 24v. Does it need to be about VD, or can the voltage supply to it exceed it? It would be easy enough to add space for a 9.1v zener at pin13 off the compander.

I need to read up. This is my first time working with different voltage options and a different clock.



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[Scruffie]

Probably just easier to show the draft schematic. The two switches are actually the jumpers underneath the BBDs to select between Vdd and Vgg depending on which chips you are using. D5 is the shunt to the VD supply.

On the compander---the NE570 is rated up to 24v. Does it need to be about VD, or can the voltage supply to it exceed it? It would be easy enough to add space for a 9.1v zener at pin13 off the compander.

I need to read up. This is my first time working with different voltage options and a different clock.

On the Compander, you'd need to adjust R11 & 12 to adjust the DC Bias, as I said the formula is on the Datasheet but I think 47k/47k is rightish without looking, rather than the 68k/68k I assume from original schematics it is now. I don't think you need to adjust anything to do with the supply voltage but i'll be honest and say Companders aren't my strong point... Rustypinto or Dirk will probably be able to help better.

Different clock? Seems to be the standard 4047, nothing should get changed with that.

Looks fine to me other than that though at a first glance... although feel free to ask any more questions, I do know a little bit about the EHX effects and delays, just not quite as much as some of the people out there!

I'll go over the schematic tonight with a few beers and see what I can see.

I assume you're remembering to switch the power & gnds on the 3205s though and that the resistor on the output of each BBD after the output mixing has to switch... unless i'm missing something.

[madbean]

By different clock I meant the 4047 instead of the MN3101 (well, it's new to me, haha).

And I have made a mistake...it's Vdd and GND that need to switch, not Vdd and Vgg. You've already helped me!

I'll email you the schem with values (on a different computer). Any technical assistance will be most appreciated (and kindly rewarded, BTW)!

[Scruffie]

By different clock I meant the 4047 instead of the MN3101 (well, it's new to me, haha).

And I have made a mistake...it's Vdd and GND that need to switch, not Vdd and Vgg. You've already helped me!

I'll email you the schem with values (on a different computer). Any technical assistance will be most appreciated (and kindly rewarded, BTW)!

Ahh I see, I have no clue about the MN3101 myself! I've always stuck with the 4047.

Whey! Glad to have helped out, yeah Vgg is supposed to be 14/15th of Vdd (a diodes drop of 0.6V is about perfect for this, however it would only work for the 3205, you'd need a voltage divider for the 3005...however that would also work for the 3205) but it's not that important really, it'll work if it's equal to Vdd.

Awesome, i'll do my best to check it over for you  values will certainly help!

One other note, Rustypinto pointed out the importance to me of keeping the 4047 Voltage Stable as it changes over the full range of 100kHz-10kHz... something to be wary of perhaps? Or perhaps he was being over cautious... i'm sure you'll find out when you prototype anyway if there are issues, I doubt it myself.

[druz15]

man would love to build one of these, have never even used an analog delay before

[gtr2]

What's the best way to tweak a little more delay time out of this beast with the 4047 clock.  I just got my new enclosure and I've got to rebox anyways so I figure maybe I can get a little more ms.

Thanks,

Josh

[Scruffie]

What's the best way to tweak a little more delay time out of this beast with the 4047 clock.  I just got my new enclosure and I've got to rebox anyways so I figure maybe I can get a little more ms.

Thanks,

Josh

Well your best bet is to actually increase the size of the Delay time pot, reason being, if you alter either the 5.6k resistor or 240pF cap in the clock, you're going to loose some shorter delay times.

But there lies your answer, increase the size of that resistor, cap or delay time pot and you'll get more delay out of it... I wouldn't stretch above 650mS though... well you might like the sound I guess.

If you change the delay time pot, you may have to play with the cap value anyway so that it doesn't get too much delay, unless you use a parallel resistor with the pot to lower its value to something more sensible, seeing as the next standard value is going to be atleast twice the value.

[gtr2]

Thanks.  I was thinking the delay pot could be changed but wasn't sure.  Adding the resistor in parallel is a great idea because the next easily obtainable value is 250kB.  I'll give it a whirl and see. 

Josh

[gtr2]

First post updated with new box pic and crummy demo 

Josh