Author Topic: CE-2 clock range  (Read 1292 times)

Mcentee2

CE-2 clock range
« on: June 03, 2018, 05:26:18 AM »
In doing some Electric Mistress (Madbean Current Lover) and HF-2 testing I took the back off my 80s CE-2 to check and compare the flanger delay times with those in the CE-2.

I was surprised to discover hardly any previous posts here that quoted likely figures for these so am at a loss to if these are "normal".

I was also surprised at the numbers themselves when the frequencies measured are worked out to ms.

Ms= 1024/(Freq*2)

These were taken using a multimeter that can measure frequ ncy at the MN3007 pins 2 and 6, rate is always on the slowest and ran for about 20 minutes each so I caught sight of the min/max.

These seem quite a bit shorter than I was expecting a Chorus to be.

I also note the schematic of the CE-2 has no Clock adjust mechanism and the available Service info doesn't mention clock rates at all, or even voltages on the clock pins.

Depth 0
148-152 khz
3.45 - 3.36 ms

Depth 50%
128-185 khz
4 - 2.7ms

Depth 100%
113 - 233 khz
4.53  - 2.19 ms

Surely somebody on this forum has done this as well over the years.....calling Mr Hammer.....

Scruffie

Re: CE-2 clock range
« Reply #1 on: June 03, 2018, 05:32:20 AM »
Well that's interesting, I had one in for repair recently and did a clock reading too as I've not seen them either and I got 75-115kHz at full depth.

Mcentee2

Re: CE-2 clock range
« Reply #2 on: June 03, 2018, 05:38:16 AM »
The only other reference I saw here was on this thread back on 2011 that were lower frequency, longer delays, as well:

https://www.diystompboxes.com/smfforum/index.php?topic=89044.0

Not statistical yet but mine seem to be the odd one!

I will redo the measurements later today, but they are fairly straight forward so not expecting anything different.

I saw no numbers lower or higher than those at either end, and the 0% Depth one sits fairly in the middle so am happy they are accurate.

The only thing I can think of is to look at and/or check the 47pF clock cap, maybe over time it has "got smaller" - is that likely ?

At least a simple test/fix is to parallel a small cap to increase the Capacitance and make the freqs lower, delay longer,  to get to that Freq range and see what it sounds like.
« Last Edit: June 03, 2018, 05:41:06 AM by Mcentee2 »

ElectricDruid

Re: CE-2 clock range
« Reply #3 on: June 03, 2018, 06:05:01 AM »
Given that the clock is being modulated and the multimeter is probably counting pulses in a given period, it might not be that accurate for a variable clock. On the other hand, if it measures the waveform period and then does a reciprocal, it might be pretty good. Dunno, just a thought. I use my digital scope for stuff like this - then I can freeze the clock waveform and measure it - but that's a luxury item for many here.

There are a number of chorus pedals with shorter delays. Here's a table I did when I was doing some research:



The famous pedal that's longer is the EH Small Clone. It has a very distinctive sound as a result. Only the Penfold Chorus on this list would be similar. If you can find the numbers for that one, let me know...Ta!

Scruffie

Re: CE-2 clock range
« Reply #4 on: June 03, 2018, 06:07:37 AM »
Only the reissue Small Clone has the much longer delay, the original one IIRC read about the same as that CE-2 I measured.

Mcentee2

Re: CE-2 clock range
« Reply #5 on: June 03, 2018, 07:27:37 AM »
Given that the clock is being modulated and the multimeter is probably counting pulses in a given period, it might not be that accurate for a variable clock. On the other hand, if it measures the waveform period and then does a reciprocal, it might be pretty good. Dunno, just a thought. I use my digital scope for stuff like this - then I can freeze the clock waveform and measure it - but that's a luxury item for many here.

There are a number of chorus pedals with shorter delays. Here's a table I did when I was doing some research:



The famous pedal that's longer is the EH Small Clone. It has a very distinctive sound as a result. Only the Penfold Chorus on this list would be similar. If you can find the numbers for that one, let me know...Ta!

Re the meter I am using, I also measured the HF-2 and Madbean frequencies, and mapped the freqs to delay numbers to pitches of the flange regards ringing when setting the clock trims (C#/D at about 7-8ms).

So I know it is at least accurate. I kept the CE-2 rate at its slowest so the meter had more chance of catching the max/min point, and also kept watching it for about 10 minutes which quite a few cycles, during which I kept noting new max/min as they appeared, so I reckon I probably caught the real max/min with fair accuracy.

« Last Edit: June 03, 2018, 08:20:27 AM by Mcentee2 »

ElectricDruid

Re: CE-2 clock range
« Reply #6 on: June 03, 2018, 07:43:32 AM »
Fair enough. If you're sure the readings are good that's cool. They're certainly reasonable figures.

T.

Mcentee2

Re: CE-2 clock range
« Reply #7 on: June 03, 2018, 07:59:08 AM »
Fair enough. If you're sure the readings are good that's cool. They're certainly reasonable figures.

T.

Indeed, it is the reasonableness I am querying, they seem a little on the short side compared to Scruffies numbers for something so "baked in" as per the schematic.

Just returning to the clock cap thought - given that cap drift is a known thing, is it possible that small a ceramic could drift smaller?
« Last Edit: June 03, 2018, 08:16:38 AM by Mcentee2 »

ElectricDruid

Re: CE-2 clock range
« Reply #8 on: June 03, 2018, 09:42:56 AM »
Indeed, it is the reasonableness I am querying, they seem a little on the short side compared to Scruffies numbers for something so "baked in" as per the schematic.

I think the numbers are feasible, but the discrepancy between your readings and Scruffie's is definitely odd. Without that, I'd be inclined to say it's fine. But instead it looks like one of you has a "outlier" pedal for whatever reason. Can we find a service manual for the CE-2? Does that have the factory delay times?

Quote
Just returning to the clock cap thought - given that cap drift is a known thing, is it possible that small a ceramic could drift smaller?

Unlikely, I'd have thought. Ceramics don't change much in my experience. The tolerances are shocking though, so +/-20% wouldn't surprise me at all.
Given that, is there any clock trim in this pedal? If there is, someone is bound to have mucked with it at some point...which might explain why two units have completely different clock readings.

ElectricDruid

Re: CE-2 clock range
« Reply #9 on: June 03, 2018, 09:55:01 AM »
Aha! Here it is!

http://music-electronics-forum.com/attachments/29491d1404312320-boss-ce-2_service-notes-service-manual-repair-schematics-online-download.pdf

No, no clock trim, and no figures for the clock from the factory. They shipped them out however they came off the production line by the looks of it.

Let's do a quick back-of-envelope calculation for it. With a cheap ceramic in the clock, they probably do vary a fair bit. +/-20% on 47pF is 39-56pF. That makes the highest ones that are still in spec 1.4x higher than the lowest ones. Scruffie's has a centre frequency of about 100KHz, and yours has a centre frequency of about 150KHz. So they're *just about* at the limits of what we'd expect. - but we only took the capacitor's variability into account. There's several other things in there that could add a bit more.

So on the face of it, there's no specific reason to think that anything weird is going on. Although there may still be, of course.

Mcentee2

Re: CE-2 clock range
« Reply #10 on: June 03, 2018, 10:59:02 AM »
Lol.

My 47pF now removed from the circuit actually measures larger at 59pF!! :)

If I put a 47pF cap in, the frequencies increase, shortening the delays even more!

Anyway, this may be practically unnoticeable?

Scruffies number work out to give a delay max/min of 6.82ms to 4.45ms, max depth delta of 2.47ms

My max depth delta is 2.34 ms

So, really it probably isn't overly aurally noticeable either way much, between the max/min delays or the warble, Scruffies may sound a little thicker, but not much.

That does bring it home to me that the CE-2 has very little "depth" - is this a thing for Chorus in general?

Or the voice design choice is more or less how short/long the delay is with just maybe 2-3ms sweep around it.

The CE-2 looks to be on the short end, light, "fluffy", mild ?

With a 47pF cap in, mine might even be approaching CE-1 !

« Last Edit: June 03, 2018, 11:31:02 AM by Mcentee2 »

ElectricDruid

Re: CE-2 clock range
« Reply #11 on: June 03, 2018, 07:02:53 PM »
Yes, an extremely "light" depth is typical for a chorus. In many ways, I'd say that (coupled with the amount of feedback) is what separates a chorus from a flanger. The actual delay ranges overlap to such an extent that it's difficult to separate them apart from the actual sound. If you increase the feedback and depth, a "short" chorus easily turns into a flanger. So the differences are in the details in at least some of the cases.
For a flanger you're looking for the most depth you can get and 1:20 or even 1:40 ratios of shortest:longest delay time are desirable with plenty of feedback/resonance, for a chorus that would be unbearably seasick and wobbly! The rules (and aims) are completely different. But that's not to say the actual delays aren't similar in some cases.

Approaching a CE-1 doesn't sound bad in any way - there'd be plenty of people who would regard that as the holy grail of chorus!

HTH,
Tom

Mcentee2

Re: CE-2 clock range
« Reply #12 on: June 04, 2018, 03:01:36 AM »
Yes, an extremely "light" depth is typical for a chorus. In many ways, I'd say that (coupled with the amount of feedback) is what separates a chorus from a flanger. The actual delay ranges overlap to such an extent that it's difficult to separate them apart from the actual sound. If you increase the feedback and depth, a "short" chorus easily turns into a flanger. So the differences are in the details in at least some of the cases.
For a flanger you're looking for the most depth you can get and 1:20 or even 1:40 ratios of shortest:longest delay time are desirable with plenty of feedback/resonance, for a chorus that would be unbearably seasick and wobbly! The rules (and aims) are completely different. But that's not to say the actual delays aren't similar in some cases.

Approaching a CE-1 doesn't sound bad in any way - there'd be plenty of people who would regard that as the holy grail of chorus!

HTH,
Tom

Many thanks Tom for clearing those points up. :)

As a connected but slightly aside question, not sure how to reach out to R.G. ?

I also have a Visual Sound Liquid Chorus, so with my newfound knowledge and frequency measuring metre I thought I would get to grips with its 4 knobs in terms of getting it close to the CE-2 clock timings.

Well, I have never really got my head around the LQ Depth control Vs the Delay vs Width controls.

Short version, with rate and width on zero the MN3207 clock pins register changes when both the Delay *and/or* Depth are changed.

With both on 100% it is at its lowest Freq of about 90-100khz, any reduction from there of either Delay or Depth move this up.

Width seems just bring in an LFO sweep.

So what gives with the Depth Vs Delay controls re how each change the clock ?

Are they basically two types of tunable Delay control where Delay only does so far, then Depth shifts it down further?

In my head I only know of two ways  to affect delay times:

Delay and Width work together in a typical Manual/LFO mix.

Depth is usually an internal clock trim (like in flangers) but here is external or otherwise blending another clock cap in ?

Whatever the answer is, it seems it is most like the CE-2 with Depth and Delay at 3 o'clock or above getting those circa 100-120khz times.

There seems a lot of available Depth and Delay left on the CCW side for even shorter times than these rather than longer/deeper on the CW side, probably a max of 5.7ms at most (lowest measured 90khz).

« Last Edit: June 04, 2018, 05:45:07 AM by Mcentee2 »

Mark Hammer

Re: CE-2 clock range
« Reply #13 on: June 04, 2018, 09:05:09 AM »
Analog delays often come with clock-adjustment trimmers since the goal of squeezing max delay out of a 4096-stage chip comes at the cost of VERY audible whine.  Chorus pedal delay ranges generally stay well above audible clock whine.

Whenever I make a chorus for myself, or get a commercial chorus I don't mind modding, I'll usually stick in a 3-position toggle to select clock-cap values for different delay ranges.  The short delays that straddle chorus and flanging are especially nice for achieving slow Leslie type sounds.

But Tom/druid's table nicely illustrates something I've contended for a long time: audible differences in commercial chorus pedals are often simply the result of very small shifts in the delay range covered.

Mcentee2

Re: CE-2 clock range
« Reply #14 on: June 04, 2018, 09:37:46 AM »
Analog delays often come with clock-adjustment trimmers since the goal of squeezing max delay out of a 4096-stage chip comes at the cost of VERY audible whine.  Chorus pedal delay ranges generally stay well above audible clock whine.

Whenever I make a chorus for myself, or get a commercial chorus I don't mind modding, I'll usually stick in a 3-position toggle to select clock-cap values for different delay ranges.  The short delays that straddle chorus and flanging are especially nice for achieving slow Leslie type sounds.

But Tom/druid's table nicely illustrates something I've contended for a long time: audible differences in commercial chorus pedals are often simply the result of very small shifts in the delay range covered.

Thankyou.

I was almost content with the difference between mine and scruffies timings to be just variance and not noticeable - however my examination of the Liquid Chorus, and your last para belies that assumption - they are indeed noticeable at such small changes.

Given the CE-2 is "hard wired" re LFO and Clock cap, and the variance/tolerance of crucial parts does indeed lead to these "small shifts", I am surprised there isn't more along the lines of "good one"  "bad one" re the CE-2 - in general it always gets a thumbs up everywhere I see...

With a Fuzz Face there are always the stories of Jimi and Eric going through boxes to get a good one - not with the CE-2 though....