Low-end realignment...

[hairyandy]

Hey all,

I was just reading up on the Ayan Smooth & Slim pedal at pedalgeek and it made me think.  The theory behind it reminded me of the old BBE units that I used in the 80's  when running sound for local bands.   It really made a mix sound much tighter and more focused in the low end and I'd completely forgotten about them.  I was thinking that a circuit like this could be a cool building block that could maybe make other pedal and amp combinations sound very different.  Imagine an AMZ Mosfet Boost with a built-in low-end realignment circuit through an old Tweed Fender Deluxe?    The other thing that struck me as cool was that the Ayan pedal is passive, so It's possible that a similar circuit could be developed that would be a cool module to add to other pedals without much overhead.

Any ideas?  Has this been talked about much?  I haven't done any searches about this yet, I was just thinking to myself and figured I'd put it up for discussion...

[hank reynolds 3rd]

Sounds interesting....maybe useful on octavers,auto filters etc ...doesn't look like there's much in it,the box looks like a 1590b...

[Mark Hammer]

Gil (Ayan) is (or at least was) a regular, and given that this is his only product from what I can tell and it is very fairly priced for something so strategically planned, I am very reluctant to embark on any discussion that might knock the legs out from under it.

At the same time, the overall topic of alignment is one that has not received nearly enough discussion here, if only to teach people about WHY alignment matters (and, by extension, why audiophiles make such a big deal out of group phase delay).

So, for those with more knowledge and time to do it, is it possible for you to search patents for more information about the underlying principles of the BBE process?  In the meantime, others can look over the specs of some of the BBE processor chips made by New Japanese radio (NJM/NJR): http://www.njr.co.jp/e05/de.html  For instance, the BBE 882 rackmount unit uses the NJM2153.  There may well be something that someone like Steve Daniels (Small Bear) might be able to get in for us folks at a reasonable price.

[GFR]

http://www.diystompboxes.com/smfforum/index.php?topic=30824.0

As Mark said, Gil used to post here, and also at Ampage and at the boogie-talk mail list (altough I haven't heard from him for some time). I have never used the S&S but it seems it is a well built product, very carefully tuned. It may be a simple circuit, but I'm sure there's a lot of hard work involved.

Gil is also a nice guy. If you wish to try some tweaking on your own, study the Mark1 mods Gil Ayan himself donated to Steve Ahola's site:

http://www.blueguitar.org/new/schem/mesa/

I think the S&S idea comes from his experience with this mod.

[hairyandy]

Thanks for the replies guys.  I would never want to infringe on Gil's product, whether he frequents this forum or not, and I'm not looking for any way to reverse engineer his hard work.  Reading about it only got me thinking about the possibilities that this process could have mainly to help other pedals do what they do better or maybe differently.  I'll have to look into the BBE processes a little more, thanks for the head start there Mark.  I'm aware that this is a fairly heated topic amongst the audiophile folks and it was intriguing to me and something that I want to learn more about.

Sorry if I gave you a start there Gil, honestly I meant no harm and being a musician that makes his living from music I'm hyper-aware of intellectual copyright issues.

Thanks again guys,

[aron]

I like Gil, so if you want something like this, buy his product.

That being said, for a long time, almost all my Shaka Pedals have been doing "low end realignment" - i.e. adjusting the low end to tighten up the sound.

Some days I want to put a switch on my pedals to switch between "humbucker input" and "single coil".

[cd]

Gil (Ayan) is (or at least was) a regular, and given that this is his only product from what I can tell and it is very fairly priced for something so strategically planned, I am very reluctant to embark on any discussion that might knock the legs out from under it.

Jeez aren't we being a little wishy-washy here?  Though I respect Gil Ayan's work, and it shouldn't be disrespected, let's not put him in the same level of contribution to the forum as say, Paul Perry or ZVex.  He has all of 4 posts here, hasn't posted in 18 months and hasn't come around in almost a year:

http://www.diystompboxes.com/smfforum/index.php?action=profile;u=1589

Anyway, I realize it's probably wise to head off an inevitable "anyone have a schematic?" comment.  Even so, if there are patents pending on the S&S, the application should be on file with the USPTO (assuming the patent was filed in the US) meaning the workings are free for anyone to view... right?

Personally, the easiest (and best) way I've found to tighten and focus the sound of a guitar and amp is the use of everyone's favorite pedal, the TS-9 Tubescreamer.  Snip out the clipping diodes, keep the volume to unity (or a hair above) and you have instant Pepto-Bismol for Fender amps.  No wonder SRV loved them!

[Mark Hammer]

Gil (Ayan) is (or at least was) a regular, and given that this is his only product from what I can tell and it is very fairly priced for something so strategically planned, I am very reluctant to embark on any discussion that might knock the legs out from under it.

Jeez aren't we being a little wishy-washy here?  Though I respect Gil Ayan's work, and it shouldn't be disrespected, let's not put him in the same level of contribution to the forum as say, Paul Perry or ZVex.  He has all of 4 posts here, hasn't posted in 18 months and hasn't come around in almost a year:

Not trying to make Gil out to be a giant in the field.  Just trying to avoid a clone frenzy and let a guy make a few bucks.  And for the record, regardless of the 4 apparent posts, Gil has a much longer track record than that, though perhaps I'm confusing his presence on Ampage with his presence here.  Keep in mind I've been here since the very first forum after Aron split from Ampage under some extremely unpleasant circumstances some years back (let's just sum it up as a very ugly über-troll who became malicious to the point of justifying litigation), so even if one has been here for 3 years there may be a whole slew of folks who are prolific contributors in my mind that may well have been elsewhere for quite a while.  For instance, J. Everman used to come here a fair bit, and there was also a time when Jacques from Jacques pedals in France used to frequent here and Ampage as "ts808".  So did Brian Marshall of Sub-Decay.  Haven't seen any of them for a couple years now.

[TELEFUNKON]

Brian`s last week appearance link to click

[cd]

Gil (Ayan) is (or at least was) a regular, and given that this is his only product from what I can tell and it is very fairly priced for something so strategically planned, I am very reluctant to embark on any discussion that might knock the legs out from under it.

Jeez aren't we being a little wishy-washy here?  Though I respect Gil Ayan's work, and it shouldn't be disrespected, let's not put him in the same level of contribution to the forum as say, Paul Perry or ZVex.  He has all of 4 posts here, hasn't posted in 18 months and hasn't come around in almost a year:

Not trying to make Gil out to be a giant in the field.  Just trying to avoid a clone frenzy and let a guy make a few bucks.  And for the record, regardless of the 4 apparent posts, Gil has a much longer track record than that, though perhaps I'm confusing his presence on Ampage with his presence here.  Keep in mind I've been here since the very first forum after Aron split from Ampage under some extremely unpleasant circumstances some years back (let's just sum it up as a very ugly über-troll who became malicious to the point of justifying litigation), so even if one has been here for 3 years there may be a whole slew of folks who are prolific contributors in my mind that may well have been elsewhere for quite a while.  For instance, J. Everman used to come here a fair bit, and there was also a time when Jacques from Jacques pedals in France used to frequent here and Ampage as "ts808".  So did Brian Marshall of Sub-Decay.  Haven't seen any of them for a couple years now.

Oh, I get where you're coming from (I used to read Ampage when it had only 1 effect section and used to be chock full of information and active posting - both on the amp side and FX side).  Just seemed kind of silly to me to be so protective of something whose workings (a) have never surfaced in the 8 years it's been in production - I think that speaks volumes already, and (b) are "patent pending", which presumably means the application is on file with the USPTO, which means any joe blow can look it up for themselves.

Can someone with patent experience comment on the application process?  Can you file a patent application and not have it appear on record anywhere in the public domain?

[Mark Hammer]

Brian`s last week appearance link to click

Well welcome back Brian!  I guess I should look at ALL of the threads, eh?    Clearly, I'm missing out on some things.  Incidentally, that Quasar is a nice little phaser.  Go to pedalgeek and give it a listen.

[aron]

I think we have talked about low end "reduction" a lot in the past - at least I remember doing so...

Gil's pedal AFAIK is aimed at a certain market  - in any case like I said buy his pedal if you want that, but we should feel free to talk about controlling the low end on our guitar signals.

[hairyandy]

Gil's pedal AFAIK is aimed at a certain market  - in any case like I said buy his pedal if you want that, but we should feel free to talk about controlling the low end on our guitar signals.

I completely agree Aron.  Sorry to stir up a whole shit-storm on intellectual property and patents, not really my intention.

As for controlling the bottom end, the literature on the Smooth & Slim reminded me of the BBE units which, IIRC, realigned the phase of the low end to tighten it up and were not just simple passive attenuators.  There are plenty of examples of attenuation circuits in my Tremaine 'Audio Cyclopedia' to try, but I'm more interested in the phase alignment idea.

Sometimes I post before I think things completely through, but then sometimes that's where the best discussions come from right?

[calpolyengineer]

Can someone with patent experience comment on the application process?  Can you file a patent application and not have it appear on record anywhere in the public domain?

Though I haven't filed a patent myself, I know that you can request confidentiality on your patent if it involves "trade secrets." However, as soon as your trade secrets are revealed, anyone can request that your patent is revealed as well.

-Joe

[WGTP]

I wasn't sure if you meant what most of us would like to do with Jennifer Aniston, or line boring your big block Chevy engine.

The Rat is famous for it's 2 resistor cap paths to ground from the feedback loop which appear to combine to effect the low-end rolloff/gain of the op amp.  In addition, the cap size at input can be adjusted to rols off some lows.  I have been experimenting with the FBL cap and input cap to effect the lower mid-range level since the 2 combined should result in a 6-12db/oct. roll off at various frequencies.  My limited understanding of filters is that they introduce phase shift that varies with frequency and roll off rate.  Is that what your talking about?   

[Mark Hammer]

A couple of months ago, I was asking about the flipping of resistor and cap in phase-shift stages.  You will note that in the stereotypic op-amp-based phase shift stage, the output of the preceding stage goes to the inverting input via a resistor and to the noninverting input via a cap.  A fixed resistor, FET, high speed switch, or LDR then connects from the noninvertng pin to ground.  This produces an increasing amount of phase shift for each stage, up to a maximum of 90 degrees, starting at a corner frequency determined by the values of the cap and resistance to ground.

So far so good.

I noticed that in some instances, I have seen the location of the cap and resistance flipped around such that instead of being fed to the two inputs via a resistor and cap the preceding stage fed the two inputs via resistors, with the cap going to ground from the noninverting input.  It was drawn to my attention that this does indeed produce a workable allpass filter but the amount of phase shift changes in the opposite direction.  That is, there is an increasing amount of phase shift (to a max of 90 degrees per stage) for frequencies below that set by the joint product of the cap and resistor involved.

What this suggests is that group delay of highs and lows can be achieved by means of:

• an active frequency divider (e.g., 3-pole LPF/HPF) to split the spectrum into high and low components
• upwards-increasing group delay applied to the high end, and downwards-increasing group delay applied to the low end

Mix those two paths together again and you get a sort of Q&D BBE, if you will, that would allow for highs to catch up with lows or vice versa.  Make sense?

[cd]

Can someone with patent experience comment on the application process?  Can you file a patent application and not have it appear on record anywhere in the public domain?

Though I haven't filed a patent myself, I know that you can request confidentiality on your patent if it involves "trade secrets." However, as soon as your trade secrets are revealed, anyone can request that your patent is revealed as well.

-Joe

Interesting - but there would still be a record of the patent application being filed, right?  I cannot find anything filed with the USPTO by anyone with the name Ayan (or Holguin) relating to musical instruments or sound.  Either I'm not looking in the right place (highly possible - I only checked two patent sites, and applications only go back to 2001), or no application was actually filed.  Even if a provisional patent application was filed, that only gives an additional 12 months to file the actual patent.  The S&S has been around since 1998.  A patent cannot be pending for 8 years, can it?

[GFR]

Mark,

I suggest that you read something about "phase equalizer" or "delay equalizer" design. Unfortunately, it's not so easy to give you references as in the case of "normal" frequency-selective filters.

In
http://www.freqdev.com/guide/fullguide.html
scroll down to below pict 15, there's a definition of delay equalizers.

There are the classic Sedra and Mitra books on active filter design, but they are somewhat heavy on the recquired knowlegdge of math...

While a delay equalizer can help make transients "sharper" if its phase response is reasonably "matched" to the phase deviations in the rest of the system, they can make things worse if it's not matched at all - (disclaimer: just my opinion now) that's why I don't think the BBE really "realigns" anything... it problably just "changes" the alignment, and if you're lucky, maybe it's sharper or better sounding.

[Doug_H]

My 2 cents:

I don't think this site has ever been about "let's reverse everything in sight and publish it just for the hell of it". For people interested in cloning here's some friendly advice: You know the s&s is a passive eq. That should be enough to get started exploring the idea. Research eq's and etc in the archives. Dare I say read a book about electronic filters, etc...

Gil's idea of using an eq to shape a guitar tone is not new or novel. However, the time he put into getting it "just right" for his particular application is where the value is here (along with the construction, of course). I don't want to see this forum used as a conduit for dispensing that info just because people may be too lazy to figure out how eq's work or do some experimenting of their own. This is a diy forum not "schematics R us"...

Having said all that, IMO the overall eq-ing discussion is good and informative. IMO *that* is what the forum is all about.

Doug

[Mark Hammer]

Thanks Doug.  Nicely put.

For those who are new at this, note that EQ and "alignment" are not the same thing.  Where EQ adjusts the amplitude/level of different portions of the audio spectrum so that nothing stands out in an annoying way (all frequencies are "equalized"), alignment involves an adjustment in the timing relationship between different parts of the audio spectrum.  There is no requirement that the levels of different frequencies be changed, although it wouldn't surprise me if there was some change, simply as a consequence of what needs to be done to re-align.  As well, when the fundamentals and harmonics of any sound source are properly aligned (so that the harmonics start at the same time as the fundamental and remain in proper phase relationship), some frequency content may to be "clearer", but that is not necessarily because it has been made louder.

Alignment is particular an issue in full-bandwidth program material.  Between the problem of trying to blend what comes out of multiple frequency-band-specific drivers into a coherent image (especially when they are different distances from the listener), and the many places and ways from input to speaker terminals where HF content can get "unyoked" from the fundamentals, there are plenty of reasons to be concerned about alignment of the spectrum so that it behaves as if all sounds coming from a given source sound like they had the same poijnt of origin.

I don't know what the S&S does, but if it is entirely passive, then there is an excellent chance that what it does is more in the realm of EQ and not alignment.  Alignment of any degree of simplicity will involve splitting the spectrum so that portions can be shifted relative to each other.  No way you could do that passively without serious passive signal loss.