tonepad Small Clone:can I use MN3207 instead of MN3007?

[Steben]

And what do I have to change to do so?
CD4047 is still useable,no. It all comes down to scaling down the voltage supply, I guess

[A.S.P.]

Ho Ho Ho: have you hugged your search-button today?

[Steben]

lol

[PenPen]

I had asked something similar a while back, I was told that it requires a lot of changes in the power supply. From what I remember, the 3007 uses a neg supply, and the 3207 uses positive, or something like that.

I'd like to see or even try designing a chorus that uses the MN3207 and CD4047 sometimes, to be the cheapest chorus possible, but I'm not sure if the sound quality would be that great.

[Mark Hammer]

The sound quality would be fine.  Many very pleasing choruses use the 3207, both then and now.

[PenPen]

The sound quality would be fine.  Many very pleasing choruses use the 3207, both then and now.

Well thats good to know. I didn't want to go saying that it would be great, since I didn't know for sure. I've read people report adding MN30expensive-as-all-hell BBD in their chorus makes it sound better, which I understand has more to do with the size of the BBD, but even still, I wasn't sure if it would sound ok using the two cheapest parts.

[Steben]

I had asked something similar a while back, I was told that it requires a lot of changes in the power supply. From what I remember, the 3007 uses a neg supply, and the 3207 uses positive, or something like that.

I'd like to see or even try designing a chorus that uses the MN3207 and CD4047 sometimes, to be the cheapest chorus possible, but I'm not sure if the sound quality would be that great.

Changing - to + shouldn't be that big a problem. Reversing some electrolytics... Gonna have a look at the schematics.

[Fp-www.Tonepad.com]

 

Fp

[analogmike]

The sound quality would be fine.  Many very pleasing choruses use the 3207, both then and now.

Well thats good to know. I didn't want to go saying that it would be great, since I didn't know for sure. I've read people report adding MN30expensive-as-all-hell BBD in their chorus makes it sound better, which I understand has more to do with the size of the BBD, but even still, I wasn't sure if it would sound ok using the two cheapest parts.

It's not the size (# of stages) that makes the 30XX sound better, but the headroom that they have. You don't want more than 1024 stages for a chorus, many good ones use 512 stages. But if properly designed, the 30XX will sound better than the 32XX as your signal will not be squashed so much in the chip. Sorry to be so scientific in my terminology 

[Fp-www.Tonepad.com]

Have you tried the MN3207 in the small clone? (of course doing whatever mods necessary to the power/etc to be able to do so).

Fp

[cd]

The sound quality would be fine.  Many very pleasing choruses use the 3207, both then and now.

Well thats good to know. I didn't want to go saying that it would be great, since I didn't know for sure. I've read people report adding MN30expensive-as-all-hell BBD in their chorus makes it sound better, which I understand has more to do with the size of the BBD, but even still, I wasn't sure if it would sound ok using the two cheapest parts.

It's not the size (# of stages) that makes the 30XX sound better, but the headroom that they have. You don't want more than 1024 stages for a chorus, many good ones use 512 stages. But if properly designed, the 30XX will sound better than the 32XX as your signal will not be squashed so much in the chip. Sorry to be so scientific in my terminology 

To expand on what Mike said, both the MN3207 and MN3007 are rated for 2.5% max THD at a certain input voltage level.  For the MN3007, this level is 0.78V RMS.  For the MN3207, it's 0.25V RMS!!  The gist of it is, the MN3007 can take a higher max input signal level, which means more dynamic range, and less noise.

[Fp-www.Tonepad.com]

Interesting.

Still, I'd like to know if Mike has been able to use the MN3207 in circuits that use the MN3007 (from what he said it appears that he has).

I'm not asking how, just if it's possible, as some here in the forum have stated that it isn't.

Even if it meant using a different power supply for the ics.

Fp

[PenPen]

To expand on what Mike said, both the MN3207 and MN3007 are rated for 2.5% max THD at a certain input voltage level.  For the MN3007, this level is 0.78V RMS.  For the MN3207, it's 0.25V RMS!!  The gist of it is, the MN3007 can take a higher max input signal level, which means more dynamic range, and less noise.

Is there a way around this? Being totally ignorant to the way BBD's work, would it be possible to run the signal line parallel into two 3207's to avoid this?

And what happens to the signal, does it come out sounding compressed, or does it actually clip and distort? Could a limiter stage before the BBD's correct this?

[cd]

To expand on what Mike said, both the MN3207 and MN3007 are rated for 2.5% max THD at a certain input voltage level.  For the MN3007, this level is 0.78V RMS.  For the MN3207, it's 0.25V RMS!!  The gist of it is, the MN3007 can take a higher max input signal level, which means more dynamic range, and less noise.

Is there a way around this? Being totally ignorant to the way BBD's work, would it be possible to run the signal line parallel into two 3207's to avoid this?

And what happens to the signal, does it come out sounding compressed, or does it actually clip and distort? Could a limiter stage before the BBD's correct this?

Think of it this way.  You can feed a 0.78V signal into the MN3007 and get only a little bit of distortion.  However, if you feed that same signal into a MN3207, you'll get TONS of distortion and bzzzz bzzz bzzz hard clipping.  Not nice if you want a nice clean chorus.

What is the solution when using the smaller headroom of the MN3207 - yes, you can use a limiter, but more commonly, effects use a combination compressor/expander (NE570 compander chip) to compress the signal (so it doesn't distort, and uses the maximum available dynamic range of the delay line) then once it's out of the delay line, expand it back to its regular dynamic range.  Read the NE570 datasheet for a far better explanation.

[bioroids]

Interesting.

Still, I'd like to know if Mike has been able to use the MN3207 in circuits that use the MN3007 (from what he said it appears that he has).

I'm not asking how, just if it's possible, as some here in the forum have stated that it isn't.

Even if it meant using a different power supply for the ics.

Fp

I've done it once (a Zombie Chorus variation) a few years ago. It was REALLY painful as it was my first BBD build, but I got it working. It wasn't too nice a chorus, but I bet someone who knows what is doing can get good chorus or flanger out of it.

Luck

Miguel

[analogmike]

CD, thanks for clarifying my techical terms 

No, I have not tried using the 3207 as I have stockpiled enough 3007s to last till I retire (I hope soon!)

[Steben]

Well, I was planning to use the compander trick on it anyway.
Actually it goes further than that: I would use two boards and make a dreaded "Small Dimension"   or something of the kind.
A third board would have companders and PCB mounted jacks for mono/stereo switching and zero flanging.
I have a nice angled enclosure box around of (in centimeters) 8 width, 15 length, 3 height in front, 6 height in back. The two boards would take 7x11 cm² and would fit in nicely

[Mark Hammer]

I started this reply before I had to go off to a meeting, so my apologies if some of it could have been more useful earlier on, or seems incongruous at the moment.

I'm not sure if I am in total agreement with you on the ranking of BBDs for chorus purposes.  In principle, the higher supply voltage in the 30xx series ought to be associated with greater headroom and all the good things that follow from that.

Across equivalent BBD size we see:

MN3007:  Vs -15V, S/N 80db, THD 0.5%, Insertion loss - 0db, Max clock 100khz
MN3207:  Vs +5v. S/N 73db, THD 0.4%, Insertion loss - 0db, Max clock 200khz
MN3307:  Vs +1.8 - +5v, S/N 69db, THD 0.6%, Insertion loss - 0db, Max clock (at +5v) 500khz

What we also see is that distortion levels covary with:  input signal level, input bias voltage, supply voltage.

What this tells me is that in the real world, the odds of being able to absolutely nail the optimum conditions for forcing both noise and distortion characteristics to be their absolute best for chip X are pretty damn low.  If anything, starting out from the base of using a 9v battery for power source means that possibilities for regulating the supply voltage to maintain it at the optimum conditions would suggest that the 3207 wins over the others by a nose, since you can regulate 9v down to 5v over some reasonable period of time, and design the circuit predicated on a stable 5v supply.

I'm not trying to be a stick in the mud.  I'm merely noting that it is the operating context, not the chip specs that make the biggest difference here.  If it is easy to maintain the optimum operating conditions, then you can obtain the ideal chip specs.  If you can't maintain the optimum conditions, then you may get those ideal specs for a short period or intermittently, but not always or predictably.

The other thing to consider is that whatever noise is contributed by the BBD likely pales beside the noise contributed by the presence of a HF clock.  Whatever you do to fix THAT noise will address the noise emanating from the chip itself.  The other thing is that whatever the minute differences in distortion and headroom are between the chips, they are probably lost if: a) you aren't using a compander to keep a ceiling on input signal levels (whihc can easily exceed what even the very best BBD's can handle under the best conditions), and b) you aren't adjusting the bias voltage with a scope and a distortion meter.  When all is said and done, the sonic quality is probably going to be affected more by the clock range used, the filtering applied, and the support circuitry (e.g., quality of clock pulse, mixing of complementary outputs, etc) than the BBD itself.

For all these and other reasons, I'm not going to favour any one of these chips over the other.  My sense is that many companies that make 1024-stage choruses have stuck with the 3207 because the possibility to regulate a 9v battery down to +5v permits the circuit to perform more consistently over time.  I don't know about you, but I've been using the same strings (D'Addario XL110's) for well over 20 years now, not because they sounded that much better than any others, but because they sounded as good as they could for a much longer period than others I tried, many of which would sound fabulous for 3 weeks and sound worse than the D'Addarios after that.  I think the same principle applies here.

[hippo]

You can find something at  www.diyitalia.com 

[Mark Hammer]

Thanks for the link! 

Interested parties should check this one out:  http://www.diyitalia.com/index/schematic/Guitar%20FX/Luix%20Chorus.gif