Anyone have info on these Otari/Sound Workshop HLP Filters?

[mjrippe]

A friend scored six of these high/low pass filters and brought them to me to figure out.  Four are marked Otari with no model number, two have Sound Workshop logos and say Model HLP4.  Google has turned up nothing.  Does anyone recognize these?  Finding a schematic or pinout would be a great help!

Thanks,
Mike

 

[analogguru]

If you have six, I would start by looking what is written on the white stickers of U2, then removing one and have a look what is written below the sticker..... maybe it is a switched capacitor filter ?

It doesn't look "japanese" (e.g. the pushbotton switch or the knobs) and judging from the split socket of U2 I would say it was only a small run.  I have no idea, why Otari should have produced such a piece - maybe some DIY-guy printed the logo(s) on these units ?

I mean, do you want some nice Otari-Compressor/Limiters ?  Shouldn't be a big problem if you pay enough....

 

[ubxf]

They look like they could be from an Otari series 54 console . And that console was a direct descendant from the Soundworkshop 34. I mixed on both of those and while they were ok i'm not sure it would be worth the trouble to bring them back to service.

 

[mjrippe]

Thanks folks. 

The Otari/Sound Workshop connection is well documented and these are clearly not DIY pieces.  The white stickers say HILO V1.0 (C) 1989 and are applied to PAL20L10NC chips - a programmable array logic IC.

Ken at Orphan Audio also mentioned the Model 54 SW/Otari board but no photo I have found of those consoles has anything like this.

Engineer Joel Hamilton says he worked on an Otari console that had some of these in the meter bridge, but his attempts to contact the owner have gone unanswered so far.

 

[leeboy1970]

hi Mike - did you get anywhere with this ? I just got 8 units in a rack but they need some work.

BTW - I believe that the pic you posted is only of the control part of the hi/lo filter, the actual filters are on a separate board. I will post pics tomorrow.

Tim, Wassaic NY

 

[mjrippe]

That would make sense, as I never got them sorted and my client sold them...