to the GURU's...

[rx5]

just 'stupified':  

hope you could answer some of me Q's

1.) how come there have been no designs for CD4069 as distortions??? just the 4049... is there a diff between the 2?


2.) is this for real?? 2SK30A are slow "switchers"? tried them in as switches(flipflop effect/bypass used in commercial gadgets) but they tend to be slow...it takes 1/8 of a sec before they turn "on"... but when I changed it with 2n5458,2n3819,J201...they all "switched" fast.... how come?? is it normal for this JFET to turn on slow??? also used the 2SK30A as audio buffers...but they tend to be muffled..as if it cant deliver the sound well... like it lags.... how come???

3.) which are the best soundign phasers?? LDR based?? JFET?? or cmos chips(as variable resistors)??

Sorry for my Q's but im just confused.....

-Ralph

[bettycat]

You are right, this is indeed a "GURUS only" thread

[amz-fx]

The 4069 inverters are usually buffered...  cascaded stages run at high gain to get fast low-rise-time switching of square waves for logic use and do not bias into the linear mode well.  The 74HCU04 is a good inverter for linear use....

2SK30A are slow "switchers"? Never heard of that one but I'll try to find the datasheet to look it over.

Best sounding phasers?  The ones you like the best...  I like the ones made from OTAs...

regards, Jack

[rx5]

I think CD4069 and 74xx04 are the same.... buffered chip is C4049 ...so biasing them in the linear region is what makes them differ..... now i get it coz i tried a CD4069 inv and it sounded TERRIBLE...not my type....4049's sounded better....

dunno how to bias OTA as a phaser..not familiar with it....


===============================
about the 2SK30A, maybe mine was LOCALLY made ..    printed on the body was only "K30A" ......

===============================

dunno how to bias OTA as a phaser..not familiar with it....

=================================

another: can a TL072 be used as an LFO single 9V supply....

[amz-fx]

4049UBE and 74HCU04 are unbuffered chips...  simple N-P mosfet inverters ... and that is best for the linear mode we're usually concerned with.

The TL072 can be configed as an LFO...  see some of the DOD schematics on my site where a single opamp is used...  I think they use a section of a TL062 or TL064 but the TL7x would work okay.

-Jack

http://www.muzique.com/

[Mark Hammer]

3) which are the best sounding phasers?? LDR based?? JFET?? or cmos chips(as variable resistors)??

That's about a dozen embedded questions, actually.

1) What provides the least amount of noise as a single element?
2) What provides a reasonable noise level for N stages?
3) What provides least distortion for input signal level X?
4) What handles the most resonance?
5) What provides the least complicated and most compact layout with the fewest layout-related sonic problems?
6) What form of allpass topography provides the most flexibility as far as noise-reduction , provision for other filter types, etc.?
7) What type of control element provides the widest usable sweep?
What type of control element provides the greatest likelihood of matching components for N stages?
etc., etc.

Each of the control elements has its strengths and weaknesses.  It depends on what you want to run into it, how many stages you want, whether you are intent on producing your own layout or using a posted one, etc.

OTAs provides great matching, and can be configured for the funky phase-filter effects, but can't handle huge input signals.  LDRs are dead quiet and handle big signals but tend to require bulkier layouts and occasionally big payouts.  FETs can be matched and selected for better sweeps, take up little room, and the allpass stage can have a feedback cap inserted to keep hiss under control, but you need to overbuy for matching and there is still the distortion issue.  MOSFet chip packages are convenient sets of 6, pre-matched, so to speak, and make for compact layouts where you can fit a dozen stages in the space of where 4-6 optical stages might go, but they tend to have worse noise specs than FETs.

So, pick your poison.

[Jay Doyle]

Not a guru by any means but I would make a bet that the SK30A's (or whatever the part number you said) have a high miller capacitance which is slowing the switching speed as well as muffling the sound when used as a buffer, though if I remember right Miller capacitance isn't an issue in a buffer config. As for the switching though I am almost certain that that is it.

A check of the datasheet might help.

Jay Doyle

[Tim Escobedo]

FWIW, I use 4069UBE chips without any problems whatsoever.

There seems to be a bit of a problem with identifying these types of chips. unbuffered chips are the ones to use for linear applications. However, I've come across several 4069s and 4049s that had no marking indicating burrered or not.

I think 4049s are mostly different from 4069s in that 4049s have higher current capability, can sink and source more power, and in my informal observation, can suck a lot more juice from a 9v battery in linear mode. Both chips can get really power hungry, but I recall some 4049s being particularly hoggish. However, this varies quite a bit ship to chip, manufacturer to manufacturer.

[amz-fx]

I found the datasheet on the 2SK30A and there is only about 1pf difference between it and the 2N5457 so I don't think that is the problem.

Did you know that the pinout of the 2sk30 is different than the 2N5457 and similar jfets? It is D-G-S while most of the 2N types are D-S-G

Could that be the problem?

regards, Jack

[Jay Doyle]

OK, not the capacitance, the pinout could definitely be a problem when used as a switch. I didn't think of the wrong pinout, guess I should have bet on that...    :oops:

[Jay Doyle]

OK, not the capacitance, the pinout could definitely be a problem when used as a switch. I didn't think of the wrong pinout, guess I should have bet on that...    :oops:

[Ge_Whiz]

Consider using the 4007 dual complementary pair + inverter. Intrinsically unbuffered, can be configured as up to three inverters or you can access the individual MOSFETs for compression, tremolo, etc. Oh, and dirt cheap too. A greatly underrated chip.

[bioroids]

Hi!

My Boss PS2 uses the 2SK30A for the switching, if I recall right. They should work fine.

Regards

Miguel

[rx5]

the pinout for MY 2SK30A is D-S-G...wierd.....datasheets indicate a D-G-S pinning.... tested it with my multimeter...

about the phasers, what phaser has the best SWEEP and RESONANCE..i think THATs what im after

[rx5]

another, how do you match caps in the filter section?? how do you know if they are matched??

Ive done my phaser in 6 stages using 4049UB chip.....




-Ralph

[rx5]

Got another idea mates.... check this out: MODIFIYING THE SMALSTONE PHASER....

http://www.lynx.bc.ca/~jc/pedals.html


havent heard the actual sound from it....gonna try it if i got time....

mine was 6 stage phaser  so i figured i make 4 switches for the 4 filters( .001uF = 1st stage, .01uF = 2nd stage, 470pF = 3rd stage, .0047uF = 4th stage) ..for the 5th and 6th, ill stick to the stock .01uF value......

i wish it would make a big difference in sound......

from what I understand, it would make the filter frequency wider because of diff value caps..... compared to the single value (.01uF) ...... but how about the "degree" of phasing... maybe it would be devided into 4..... since your running the filters at 4 different freq..... or am I  wrong

regards


-Ralph