Danelectro Fab Chorus chips

Electron Tornado · January 30, 2012, 09:45:57 PM

I understand the main chip in the Danelectro Fab Chorus is the same as the one used in the Boss CH-1. Can anyone verify which chip is in the Fab Chorus?

Thanks

Mark Hammer · January 31, 2012, 09:26:34 AM

There are not too many analog chorus pedals that will NOT use an MN3207 or replacement.

Thomeeque · January 31, 2012, 09:33:02 AM

(source)

Looks like PT-something to me.. Pretty far from this..

T.

Govmnt_Lacky · January 31, 2012, 09:39:14 AM

PT2396 perhaps

Looks like too many leads to be a 2399.

Thomeeque · January 31, 2012, 09:46:17 AM

That gutshot instantly gave me flashback to my never finished ~~PT2397~~ PT2398 based »ELECTRIC PRINCESS« project

:

I was aiming for flanger which I could not get, chorussy sounds were actually quite nice..

T.

Electron Tornado · January 31, 2012, 10:16:16 AM

Hmmm...could be a PT2397. In 2001, I think, Boss changed the design of the CH-1 and began using the ES56028 echo sound processor chip: http://pdf1.alldatasheet.com/datasheet-pdf/view/165437/ETC1/ES56028.html which is also a 28 pin chip.

Mark Hammer · January 31, 2012, 11:57:24 AM

Well....I guess that would be one of the few not using a 3207!

Thomeeque · January 31, 2012, 05:18:27 PM

Sorry sorry sorry! It was PT2398 based project, I have used PT2397 only for the first tests (and first shots) - it is pin compatible with PT2398 and I did not have PT2398 yet. PT2397 is functionally 100% equal to popular PT2399 only in DIP28, could not be used for the standard chorus due to long delay times. PT2398 is much better candidate for chorus thanks to wide range of short delay times and it is equivalent of ES56028! So you were probably right. Btw. I have posted some of my finding about PT2398 here (and here).

Good luck, T.

Electron Tornado · February 01, 2012, 04:55:44 PM

Tomas, thanks for the info and the links.

Thomeeque · February 02, 2012, 08:07:31 AM

Quote from: Electron Tornado on February 01, 2012, 04:55:44 PM
Tomas, thanks for the info and the links.

You're welcome, E.T.

Btw. do you have schematic of ES56028 based CH-1? I've tried to find it (I'd like to see how they used this chip), but all I have found was MN3007 based version in many different forms..

Cheers, T.

Electron Tornado · February 02, 2012, 10:08:07 AM

Tomas,

You can download both CH-1 schematics here: http://www.eserviceinfo.com/index.php?what=search2

The one with the ES56028 is the "Boss CH-1T.pdf"

Thomeeque · February 02, 2012, 10:25:52 AM

Great, thanks!

Looks like they've spend some time on fine-tuning their modulation method, local PT2399 torturers should check it out

More direct link for others interested: http://www.eserviceinfo.com/downloadsm/41775/Boss_CH1T.html

Btw. I love that site, I've found there a lot already.

T.

Electron Tornado · February 02, 2012, 10:46:21 AM

Take a look at the application notes in the ES56028 data sheet. It looks like Boss basically took the "surround" circuit and added an LFO.

Thomeeque · February 02, 2012, 11:02:23 AM

Quote from: Electron Tornado on February 02, 2012, 10:46:21 AM
Take a look at the application notes in the ES56028 data sheet. It looks like Boss basically took the "surround" circuit and added an LFO.

Sure, there's probably not much you can do around basic topology (if you want to use it as an delay line). But hey, they have added one more order to LPFs and tuned them differently and for chorus effect is modulation (way of adding LFO) THE KEY - and as I said, it looks elaborated really carefully.

T.

PaulBass · July 20, 2013, 01:05:50 PM

I have one of these but can't find the schematic anywhere. anybody know where the input & output caps are and their values?

Thomeeque · July 20, 2013, 01:16:16 PM

sorry, misunderstood

Thomeeque · July 20, 2013, 01:20:02 PM

damn, wrong button this time

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Danelectro Fab Chorus chips