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...
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.
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..
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.
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?
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.
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
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...
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.
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?
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?
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!
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
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
8) 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
8) 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
8) 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
8) 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....
Sorry Scruffie, this one's a PITA.
I'll get the trannie numbers in tonight...
Your help is greatly appreciated.
Waiting for your trannie measurements before making judgement ;)
Measured with regulated PS @9.13v
Width 100% dimed
Manual 0
Regen 3/4
Sweep 0
=============
Q1:
C1 480mv
B2 472 - 480mv
E3 3mv
Q2:
C1 8.7 - 10.7v
B2 2.1v
E3 1.49 - 1.8v
Q3:
C1 1.49 - 1.8v
B2 400mv - .6v
E3 3mv
Q4:
C1 14.76v
B2 6.4 - 8.0v
E3 7.9 - 6.1v
Q5:
E1 14.76
B2 14.21 - 14.71v
C3 8.6 - 10.74v
IC5, Pin 8, measure it again.
Will do, looked at datasheet and that should be ground. Hmm.
Yup, the 4049 not working due to no ground could certainly cause you to loose flanging above 500KHz as the clock can't get over the 3007s clock capacitance without the help of it.
Well it looks like my mistake as IC5 pin 8 is grounded.
.4mv by my DMM.
How do the Trannie voltages look to you?
Well... I think you measured Q2 wrong unless there's something really wrong so do check that again but it looks like just a mistake. Otherwise far as I can see they look okay.
I do wonder why your voltages aren't a bit steadier, but it could just be your meter settling...
Could be a bad joint or poor socket connection somewhere though.
Measured with regulated PS @9.13v
Width 100% dimed
Manual 0
Regen 3/4
Sweep 0
=============
The voltages are fluctuating consistent with the sweep on all of the IC pins noted with two voltages. (going up and down with the sweep)
I'm using an auto ranging DMM so the setting is DC.
The ampere readout from my bench supply is also fluctuating consistent with the sweep from about 50ma to 100ma. (going up and down with the sweep)
I'll check the Q2 pins again.
don't think it was a mistake but easy enough to check.
I messed up on Q2 as you suspected. I have corrected it in the above numbers.
Correct me if I'm wrong but I'm beginning to think this is just the way this circuit behaves.
ARRRRRrrgh!
Quoteor if 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.
If the above is the case, how would I mod this to compensate?
I listened to Brian's demo from a few years ago and listened to an original MXR and it seems to me Bean's build does the same thing mine does.
http://www.youtube.com/watch?v=T3pJwksh_6A (http://www.youtube.com/watch?v=T3pJwksh_6A)
When Brian at about 1:15 into the demo, sets his unit with slow rate and almost full width, it stops flanging at the top. this is exactly what mine is doing. Near the bottom there is a clump of flanging.
http://www.youtube.com/watch?v=7JYyF97dZWI (http://www.youtube.com/watch?v=7JYyF97dZWI)
Start about halfway through the video.
Sorry if this breaks some kind of DIY unspoken ethical code. I have always gotten in trouble due to a lack of filtering in that area..
Daniel
If it sounds like that then yeah it's fine, there is some flanging going on it's just a very short delay so it can be hard to hear. In the original tape flanging effect (look up how it's achieved) when this point is reached the 'sweep' keeps going to the through zero point where the sound becomes almost lost but in a heady everything's weird way, flanger pedals with a single delay line can't have a delay shorter than the original input signal so never achieve this and can get pretty high up there, but then come back down.
You can hear it used here;
http://youtu.be/JGEgRnvFzLY?t=49s
Put a fuzz up front of the flanger and you'll hear the sweep clearer.
I used flanging in the 60s when you actually had to put your hands on the tape flange... I remember that song when it first came out...8-)) Yea I know old fart....
Is there a Zero Point flanger in the electronics world that you know of? Very interesting that that is what is going on. Thank you for spending the time to help educate me on this stuff! I have learned a lot regarding LFOs and BBDs.
So if you used a dual line of delay chips you could achieve a zero point flange crossing? Or would it be easier to just get a couple of old half track tape recorders? LOL
daniel
There are 2 analog ones in production I know of, the Foxrox Through Zero Flanger & Flanger Hoax, DIY there is a project by DrAlx on DIYstompboxes.
Couple of digital ones about too...
Thanks !
Well after hearing the FoxRox i think it's time to come up with something that is like the reality of what tape flanging is, if possible.
Strymon's offering sound good but still...maybe have to make a tape based machine to get the reality of zero point? Pretty sad that the original tape flanging has turned into this approximation of what used to be so cool.... Just my 2 cents worth..
If zero point flanging isn't a make or break point, there are some very excellent flanger projects.
Keefe has his miniature (relatively) A/DA Flanger project, the Arquebus, IIRC... mine isn't working yet, need to order more pots.
Electricstorm has released his build doc for the Lovetone ? Flange With No Name. This one isn't as good a pure flanger as the A/DA, but is very good at the flat out weird crap.
I have a Flintlock to build....