All 4558's are not created equal! - Mu-Tron Phasor II proves it

[crb3]

As far as the dots go, They aren't consistently where the orientation dot is, so that probably isn't the reason. 
.....
I suppose we could just ask the inventor at
http://www.mu-tron.org/
whether they matched op amps...

I sent him an email.  I'll let you know if/when he replies.

I don´t think that they were "MATCHED", maybe they were "selected" - for low input current.
Put some TL072 instead of the 4558 and look/listen what happens.

analogguru

More likely. An old girlfriend of mine worked in a burn-in/test facility for semiconductors here in New England. The ones that survived burn-in and tested to (customer-provided!) spec got a dot of paint as a cert-mark. The dots in those photos look a bit familiar...

re: test set... I'd suggest an additional test shot: with zero input signal, with old chips and with new chips. Is there low-level parasitic oscillation snuffing out the null? Is there DC offset -- from where? I'd expect DC gain and gain-bandwidth product to both go up a little over the decades as processes are tweaked and dies are shrunk. Those lateral-PNP input transistors maybe behave a little more like respectable PNPs now.

[bool]

Offtopic: Any experience with KIA4558 ( DIP package) opamps? Passable or "to avoid"?

[R.G.]

Offtopic: Any experience with KIA4558 ( DIP package) opamps? Passable or "to avoid"?

Horses for courses.

They're perfect for some things, not as good as other opamps for other things.

But - what things? You have to know what you want them for.

[bool]

Well, for the "4558 tone" where applicable - in OD or "gain" circuits. The KIA seems way cheaper (locally) than the other "4558's" so there. Not expecting an overwhelming amount of mojo, but the same question: Is it passable, is it OK-ish - or better to avoid and look elsewhere.

If you have first hand experience, how's noise?

[R.G.]

I don't know of any way to measure the "4558 tone" or its mojo, so it's going to come down to a listening test.

If they're available locally, doing a listening test is probably going to be faster than getting a dozen different opinions here and then doing a listening test.

The KIA isn't available locally for me, or if it is I haven't seen it, so I can't say about the mojo/tone/etc.

How do the datasheet noise specs compare for the KIA and JRC4558 parts?

[Voltron]

Yeah, listening tests.

You'll need something to compare, thou.

If the situation narrows down to not have a correctly working circuit / pedal at hand, and only a schematic and 1 option opamp, I think you'll pretty much stuck with what you have.

If you looking for some numbers to tell you the RIGHT thing, then maybe you should (re)read this whole discussion from start.

P.D.
If you dont want to cash out for new 4558 then scavenge old audio equipment. Even not so old DVD players with karaoke functions come equipped with JRC4558 for the mic input and a PT2399 for the echo. If you see analog controls for volume and echo on the outside then you'll find those inside.

Hey, not usefull for mass production but handy when you need extra components to compare and then tweak your circuit.

[Voltron]

How do the datasheet noise specs compare for the KIA and JRC4558 parts?

Is " Vni " usefull for that?

KIA4558  (2002 rev)

RS=1k , f=30Hz 30kHz                TYP 2.5   uVrms

NJM4558  (2014 rev)

RIAA RS=2.2kΩ,30kHz LPF           TYP 1.4    uVrms


So sonfusing. Old Raytheon datasheet doesn't even match slew rates with JRC.

[PRR]

> I don't know of any way to measure the "4558 tone" or its mojo
> I can't say about the mojo/tone/etc.
> How do the datasheet noise specs....

Mojo is right on the data-sheet:


_______________________________________________________________________

> RIAA RS=2.2k?,30kHz LPF           TYP 1.4    uVrms

Problem there is the "RIAA", a circuit with strong treble loss in the "hiss" range.

A graph suggests spot-hiss of 10nV/rtHz over the audio range. Times root of 30K, is 1.7uV.

I would not put TOO much trust in either spec. NJM is likely to do a bit better, audio is/was a primary part of their business. I don't know who KIA is, if the number is high because they don't really monitor their product's hiss, or the reality is higher because they don't care about chips or specs. Or spec-numbers can be high to steer you to another product (at higher price).

Also we only have a voltage-hiss number. Bipolar inputs have significant current hiss, and guitar-thing impedances can be high enough for this to swamp voltage hiss. We could estimate current hiss from bias current (assuming no cancellation) but a listen-test is much quicker than math.

[bool]

Well thanks for all responses, however I was really hoping for someone who has actually used and abused the said kia chip. These days I have next to nil time to do any testing at all, and as you scholars aready noted, datasheet data arent exactly comparable, plus in-vivo testing is what these 4558's are all about... Datasheet numbers are for micpres. (perhaps the slewrate "improvement" could explain that "originals" tend to have the mojo and newer chips often don't?)

[R.G.]

Awesome thread! Wanted to jump in and let you all know that I have authentic Texas Instruments RC4558P available here:

What else in the way of help to people learning to build pedals other than just advertising chips for sale do you have?

You have four posts, and they're all involved with advertising ICs for sale. This one is a response to a thread last added to in December 2014.

[armdnrdy]

Awesome thread! Wanted to jump in and let you all know that I have authentic Texas Instruments RC4558P available here:

What else in the way of help to people learning to build pedals other than just advertising chips for sale do you have?

You have four posts, and they're all involved with advertising ICs for sale. This one is a response to a thread last added to in December 2014.

When I saw the thread about the PT2399s....this was my thought exactly! Spam

Also, You may not have noticed...so I will point it out to you...this site has a store.
The sales from this store help offset the operating costs of this site.
I don't believe that Aron...our fearless leader would appreciate you advertising the same items on HIS site....unless...you give him a commission...lets say...75% 

[snap]

In his defense we have to admit, that he left almost 45 minutes between registration and this post?

[R.G.]

Forty five minutes between registering and first advertisement? Wow. New record!   

[Cjuried]

With all do respect, I am here to learn, teach and assist. Yes, I do happen to sell authentic and genuine electronic components, as I order quantity for my projects and have little use for the overstock. With that said, why not offer them at reasonable prices to others that would find use for them?

Sincerely,   
Chris Juried
Audio Engineering Society (AES) Member
InfoComm-Recognized AV Technologist
Juried Engineering, LLC.
http://www.tubeequipment.com (Tube Equipment Corporation)
http://www.historyofrecording.com (HistoryOfRecording.com)

Forty five minutes between registering and first advertisement? Wow. New record!   

[Cjuried]

Message posted in error.

[Govmnt_Lacky]

Hmmmm......

How was Cjuried quoted on a post on 15 August (above) and then he replied again with his resume signature...... yet he has only 1 post 

EDIT: Now it is 2 posts since he quoted himself... 

[duck_arse]

I'd guess he's been smited. that must hurt.

[Govmnt_Lacky]

I'd guess he's been smited. that must hurt.

And allowed to come back... with the very same username... and post another ad? 

[Cjuried]

No ad posting here. Learning quite a bit reading these threads, though. 

[Sophie]

I realise that this is a very old thread - but then after all, *I* was interested enough to read it and it remains here as interesting reference material.

I built a clone of the Muton Phasor-2 by butchering a Bell phaser.  The board was close enough in general to do a build with a few small tweaks here and there.
- I never did get it to sound quite as succulent as the real pedal.  Close.....but not quite - although I have not yet given up and am thinking of revisiting the problem after a 15 year lay off from even playing.
In searching for stuff about the pedal, I found THIS which (apparently) gives details of how the original Mutrons were set up and tuned.
http://www.bruynooghe.fr/public/effets_vintage/Phaser/MutronMU-01PhasorIIServiceManual.pdf

I add it here because it may in the future be the answer some lost soul is pining for  :-)