Unanswered Collosolus question of the Universe..

[blearyeyes]

Why is it that my Colosulus build and my Porkbarrel both seem to go outside of the area where there is flanging or chorus on the top of the LFO sweep regardless of trimmer settings?  Hmmmm...

I hear it on DYI demos a lot but not so much on manufactured pedals. Doesn't sound bad, just not quite right.
Must learn why...

[Scruffie]

Do you have a multimeter with a frequency counter? Measure the clock frequency at the BBD (Pin 2 or 6 of the 3007) on both pedals if so and post the results, slowest rate most depth is probably the best.

[blearyeyes]

Collosalus
75k to 970k

Pork Barrel
45k to 67k

on second listen the Pork Barrel is good and sounding like I remember in the old days.. must have been a demo or something else..

I have a Flintlock, Space Harp, Pennyroyal & Celeste waiting so I really would love to understand this a little better..specially for the flintlock..

[Scruffie]

Closest I can find for readings at the moment is that the Collosalus should swing between approx 30KHz to 960KHz, it could be as you have a reduced sweep ratio of 12:1 instead of 32:1 it's just spending too long in the shorter delay times and you're not hearing it so well.

Can you explain the sound a bit better... is it like the flanger 'skipping' at the top of the sweep is there a dead sounding spot or does it just sound weak etc.

[blearyeyes]

Yea, wish I could just record it.

ok I just read a short piece by Brian regarding how clocks and BBD chips work. I think what you said:

"it's just spending too long in the shorter delay times and you're not hearing it so well."

That is accurate.

There is no skipping or anything. The sweep is smooth but not much is going on while the sweep is moving up and around the top. I would rather the LFO/Clock stay within the range where the deeper flanging is going on. I'm going to assume that would be in the longer delay times / lower clock frequencies?

What sets the range for the top and bottom of the clock frequency? Isn't it a Bi-polar cap in the LFO circuit?

[Scruffie]

A combination of C22 and the clock trim set your frequency range.

Increasing C22 will allow you to reach lower frequencies which equate to longer delay times.

So you want to adjust it so your clock measurement at the BBD is sweeping from approximately 30KHz to 960KHz. I wouldn't go lower than 30KHz but you can go higher than 960KHz if it'll sweep there.

[blearyeyes]

Thanks Scruffie, your the best.

Lower frequency means longer delays between the buckets in the bregaid....

Looks like the clock frequencies add up to what I'm hearing.. not quite low enough and too much on the higher frequencies..Thank you so much for taking the time to help a semi noob. I have a feeling I'll always be a semi noob...lol

daniel

[blearyeyes]

Got back to testing today. The pedal stops flanging at about 400k  All of the flanging is at lower frequencies and basically stops above 350-400k. The clock is going from 40k up to 950k+ so there is half of the sweep with little or no flanging. 


Could it be the MN3007 ?

I'll pop another in there.....

Tried 4 still the same...

[Scruffie]

I'm confused... is it reaching 350-400 or 950k+?

So you can get it to sweep from 40k to 950k plus? If so... add more capacitance to C22 to bring it down to 30 to 950k.

It may be there is another issue at hand (and I remember you had many with this build) or, despite the clock buffer and the original BBD being 1024 stages, changes are needed to the VCO to achieve the original sweep due to increase in clock capacitance.

[blearyeyes]

I have it sweeping per spec.
So raising C22 will limit the width of the sweep?

Seems like it would be worth limiting the control frequency to sweep between 30khz and 500khz for the MN3007.

Does that make any sense?

[Scruffie]

No...

Raising C22 will drop the minimum clock frequency available but not limit the range (to a point) and certainly limiting it wouldn't be a good idea, it should be perfectly possible to have it sweep the full range so that it sounds the same as an original, limiting would defeat the point of it.

C22 was selected at the factory in the original, the same applies here.

So you now having it sweeping 30KHz to 950 correct? Does it sound okay now?

[blearyeyes]

All is well, the chip does not flange from 500 to 950khz but with the width and manual pots you can set it to function well.  Just an unanswered question of the Universe!

Thanks!

[Scruffie]

Hmm if you hear no flange at all from 500 to 950KHz everything is not well...

Can you post voltages for Q1,2,3 & 5 and IC's 3,4,5 & 6

[blearyeyes]

Measured with regulated PS @9.13v
Width 100% dimed
Manual 0
Regen 3/4
Sweep 0
=============
IC3

1) 1.4
2) 7.45
3) 12 - 3.38
4) 1MV
5) 7.5
6) 7.59
7) 12-3.60
2.9-10.9
9) 14.73

IC4

1) 2.21
2) 2.2
3) 2.2
4) 1MV
5) 7.3
6) 7.37
7) 7.36
14.76

IC5 voltages are oscillating with sweep

1) 14.76
2) 7.02 - 7.35
3) 7.16 - 7.37
4) 7.17 - 7.37
5) 7.24 - 7.37
6) 7.14 - 7.37
7) 7.24 - 7.38
7.13 - 7.37
9) 7.13 - 7.36
10) 7.05 - 7.36
11) 7.03 - 7.36
12) 7.05 - 7.36
13) 7.0MV
14) 7.16 - 7.36
15) 7.03 - 7.36
16) 116MV

IC6

1) 7.37
2) 7.37
3) 10.29 - 14.43
4) 0.5MV
5) 7.37
6) 0.5MV
7) 0.3MV
14.72 - 14.76
9) 14.76
10) 8.26 - 10.42
11) 14.63 - 14.76
12) 10.31 - 14.45
13) 14.76
14) 14.76



Gotta sort out the trannies pins....

[blearyeyes]

Sorry Scruffie, this one's a PITA.
I'll get the trannie numbers in tonight...


Your help is greatly appreciated.