Building a 1178 lookalike/dual 1176 replica out of a UREI 535 EQ

[Zebra_PD]

Hi!
I'm new kinda to the diy world. Been building a U87 clone but that's pretty much it.

I would really like to build a 1178ish clone and just bought a UREI 535 EQ for cheap (about 60€).

I opened it up and found out that the output transformers (12614) and the power transformer (16-12261) is the same as in the one of the early 1178 models right?

Is there perhaps some other components worth saving in the EQ for the build?

What 1176/1178 version would you guys recomend me to build? Preferly one that has a step by step build guide here on the forum or elsewhere online.

I'm also going to build gyraf 1176 dual kit prior to this build if anyone might suggest that I better build something "easy" before attempting this project

https://photos.app.goo.gl/4TNcMygiPcdGgy2t2

 

[Zebra_PD]

*Update*

Well the 12614 output transformer is used in the late silverface 1176/1178 and not in any other versions if I'm correct?

And the  power transformer (16-12261) is the same as the 1178?

But I haven't found a PCB and/or project online for a 1178 clone. Or for a 1176 silverface for that matter. I guesd PCB grinder had a 1178ish  clone pcb couple of years ago but no longer if im not misstaken.

So if I would get someone to make me a custom 1178 PCB, is there some other parts (original or replacement) besides trying to find a replacement for the special dual jfet, that would make this an "impossible" mission?

 

[pvision]

A 535 is the perfect basis for an 1178 clone. The only strangeness I've found when repurposing UREI cases is that when using a 527A case and a genuine 1178 front panel the mounting holes don't line up. Makes no sense so my conclusion is that the two-channel units may have a slightly wider case. If you're having a custom front panel made it won't be a problem

The 1178 uses different output transformers and I haven't tracked down what other UREI models use them. However I wouldn't worry about it too much - just use the 535 output configuration inc transformers

The 1178 is a different to most models of 1176, and sounds slightly different. It's was released quite late in the model run, IIRC, around the time of the Rev H 1176. Certainly it shares the front panel design of the Rev H with the logo badge

Gustav produced a dual FET design based on the 1178 but don't think he has boards for it any more. He still does boards for his MS76 design

https://pcbgrinder.com/index.php?route=product/product&path=65&product_id=103

Nick Froome

 

[Zebra_PD]

Thanks Nick for your reply and info!!

Ok, haven't had a chance to study the schematics and components list of the 353 and 1178 side by side yet. Just assumed the output transformer for the 1176LN Silver-Face and the 1178 was the same. But you think they will work fine for a 1178 build anyway?

I found Gustavs old thread for the dual fet 1178 clone project here in the Drawing board subforum.

I'm going to send him a message if he might have some PCBs left or still have the gerber to order one.


*update* I did also found the build thread so scratch the comment below.
https://groupdiy.com/index.php?topic=56181.0

I posted a reply there asking if he might have found a replacement for the jfet and if he might have some PCB still in stock. Didn't find any old "build thread" in the Dynamic processors subforum.

 

[Zebra_PD]

If anyone is interested I found the original 1178 manual on the UREI/JBL site.
http://www.jblproservice.com/pdf/Vintage%20JBL-UREI%20Electronics/UREI-1178%20manual.pdf

According to the schematics the output and power transformer seems to be the same as in the 353. So thats good for me

Also got a hold of a NOS frontplate this morning from Korea for about 120€ ink shipping. (whoop whoop!) It will be interesting if the same issue as Nick wrote about above regarding to fit it to a 527A base will apply for the 353 case as well. Otherwise I will have to find another way to attach it.

Also posted in Gustavs old build thread for his 1178 klon. Hopefully he can answer some of my questions there in regards of using that design for the base of my build. 

 

[TheJames]

The heart of the 1178 is the dual FET DIP.  You'll need those to make a clone.  Ebay seems to have some listed although I'm always a bit hesitant to buy "obsolete" semiconductors from ebay.  For a few bucks it might not be to bad to try it.

Studio Electronics here in the States has them:

http://www.studioelectronics.biz/sunshop/index.php?l=product_detail&p=1176

Kind of pricey.

 

[Zebra_PD]

The heart of the 1178 is the dual FET DIP.  You'll need those to make a clone.  Ebay seems to have some listed although I'm always a bit hesitant to buy "obsolete" semiconductors from ebay.  For a few bucks it might not be to bad to try it.

Studio Electronics here in the States has them:

http://www.studioelectronics.biz/sunshop/index.php?l=product_detail&p=1176

Kind of pricey.

Thanks you for the link! Good info if Im not able to find a good NOS dual jfet.

 

[Zebra_PD]

So I have been looking at an another critical difference between the 1176 and the 1178 today. Yes I know its probably obvious for someone not a newbie like my self but Its the ratio switch layout.

Im correct if the ones used in the Hairball kit wont work for me right? They only work to control a mono kompressor like the 1176? I need more then the 3 by 3 pins.

would these work for the 1178? https://www.ebay.com/itm/NOS-Hafler-JF200-RF200-4-Pushbutton-Switch-Assy-SW-526-4-X-4PDT-Interlocking/222916420900?_trkparms=aid%3D222007%26algo%3DSIC.MBE%26ao%3D2%26asc%3D44039%26meid%3De4e191b0912d47a099202c8d979b321b%26pid%3D100011%26rk%3D1%26rkt%3D1%26sd%3D222870934269%26itm%3D222916420900&_trksid=p2047675.c100011.m1850

Would I in that case need 1 or 2 of these? Could I use the same ones as for the 1176 to control the meter/power section?

 

[pvision]

The only differences between the 1776 and 1178 on the front panel are two sets of input & output pots, a stereo / A+B switch and the bottom RH pushbutton which is power on / off on the 1176 becomes peak / average on the 1178. The 1178 also has a separate power on / off switch

Switches for an 1176 should work assuming they have sufficient ways for the 1178. Both banks are non-latching

The 1178 was fairly obviously an attempt to get round the (lack of) stereo balancing of a pair of 1176s so will need FETs matched as closely as possible. The circuitry of the 1176 uses two FETs per channel, one for audio and one for metering, but it looks like the 1178 has ditched the FET for the metering

Nick Froome

 

[pvision]

If you print the schematics for a 535 and an 1178 and go over them with a highlighter you'll soon see that UREI used some basic building blocks in lots of their gear

I'd locate one of Gustav's boards and his schematic and find how best to merge the two. UREI has done most of the work so I'd piggyback on that as much as possible

The 1176 circuit is very simple conceptually - input buffer, FET, preamp, line amp, sidechain & meter. Once you identify the blocks you should be able to see how to work with what you have

If you download the 1176 manual you'll find it has schematics for all the versions. That will show you how the guts change very little while the input & output amps go through multiple iterations

I haven't looked hard at an 1178 schematic for a while but I'd bet it's very similar to the 1176 Rev G or H

Nick Froome

 

[Zebra_PD]

If you print the schematics for a 535 and an 1178 and go over them with a highlighter you'll soon see that UREI used some basic building blocks in lots of their gear

I'd locate one of Gustav's boards and his schematic and find how best to merge the two. UREI has done most of the work so I'd piggyback on that as much as possible

The 1176 circuit is very simple conceptually - input buffer, FET, preamp, line amp, sidechain & meter. Once you identify the blocks you should be able to see how to work with what you have

If you download the 1176 manual you'll find it has schematics for all the versions. That will show you how the guts change very little while the input & output amps go through multiple iterations

I haven't looked hard at an 1178 schematic for a while but I'd bet it's very similar to the 1176 Rev G or H

Nick Froome

thank you a million Nick!!!

My plan was exactly that to first compare the 353 and 1178 schematics side by side to se what I might be able to save. After that my plan is to draw up a digital version of both the original 1178 and import/copy a version Gustavs design into the software. Gustav did not still have the project files and gerber file and no boards still in stock. So will need to make my own files from almost from scratch.

Will prop build a dual/stereo version of the 1176 as well from an early Gyraf kit that I might get a hold of from a fellow producer here in sweden that he bought but never built. So for this project I'll will get the NOS stereo JFETs instead of trying to match two JFETs .

After that I need to also decide if I would like to incorporate  the Jim Williams 1178 mod into my build from the begining or not.


Yes have done some reseach regarding the similarities of 1176 vs 1178 and what i have gathered so far is the rev H the closes one. No input transformer, oamp design and UREI branding on the front. But using a different output transformers, one per channel (same one as in the LA4) and a stereo JFET instead of a mono one. When I have done a more in deep study of all the original UREI schematics I´ll post my thought/finding here in this thread.

 

[trashcanman]

I’m looking to get some dual fets for a stereo 1176 I’m working on. Have you found a legit source for them yet?

 

[pvision]

There's a previous reply showing a DIP version from Studio Electronics at $35

There's easily $30-worth of faffing around involved in trying to source something similar so I plan to buy straight from SE

Anyone interested in stereo FET limiters should also seek out the Orban 418A. It's a beautiful piece of kit, like all Orban gear, and sounds great.

Nick Froome

 

[Zebra_PD]

I’m looking to get some dual fets for a stereo 1176 I’m working on. Have you found a legit source for them yet?

nope haven´t found any other source or alternative then the ones from Studio Electronics.

Still in the process of planing the custom PCB. Still waiting for the original 1178 front plate to arrive so I know where to put the spots for the pots and meters

*update*

Studio Electronics seem to be out of stock... found this listing in Hong Kong on ebay. If you are located in europe perhaps we could order together to save some money in custums feeds etc. seed me a PM if so

https://www.ebay.com/itm/NSC-NPD5566-Integrated-Circuit/401477960046?hash=item5d79f3816e:g:EvQAAOSwo4pYD2lC

 

[PRR]

> save some money in custums fee

https://www.manotoh.com/a-47558571/linear/npd5566/
NPD5566 € 11,90 Stock 40 pcs. 
Wide band low noise dual Jfet, PDIP-8
Manotoh BVBA, ..., ​BELGIUM

 

[Zebra_PD]

> save some money in custums fee

https://www.manotoh.com/a-47558571/linear/npd5566/
NPD5566 € 11,90 Stock 40 pcs. 
Wide band low noise dual Jfet, PDIP-8
Manotoh BVBA, ..., ​BELGIUM

Ohh thank you for the link!!!

 

[pvision]

The supplier in Belgium has a €50 minimum order value. I'd be in for one if someone wants to make up an order

Nick Froome

 

[trashcanman]

I’d probably be interested in two of those also., assuming they aren’t fakes.

 

[Zebra_PD]

The supplier in Belgium has a €50 minimum order value. I'd be in for one if someone wants to make up an order

Nick Froome

Perfect! I'll prob make an order within the next month or so. Just need to plan the rest of my BOM to see if there is anything else I might need to order from the same site that I cant find on Mouser or similar. Send me an email to pierre(a)zebrastudios.se and we can take it from there

I’d probably be interested in two of those also., assuming they aren’t fakes.

Well seems like a legit store to me, feels more safe then ordering from China/Hong Kong. Send me an email at the same mail as above if u would like to order some too.

Also curious about your 1176 stereo version build. Is it based on the 1178 or a custom design of your own based on one of the 1176 REVs?

 

[Zebra_PD]

The only differences between the 1776 and 1178 on the front panel are two sets of input & output pots, a stereo / A+B switch and the bottom RH pushbutton which is power on / off on the 1176 becomes peak / average on the 1178. The 1178 also has a separate power on / off switch

Switches for an 1176 should work assuming they have sufficient ways for the 1178. Both banks are non-latching

Nick Froome

Bare with me Nick here comes a real newbie question since I didnt understand all of that

Looking at at picture of the inside of an original 1178 and pictures of an original 1176 the switches seems to differ in size and connection pins(ways?). So what do you mean with non-latching? That both banks can be connected to the same pins on the switch? So you say its still possible to use for example a 3x3pdt switch bank used in a 1176 clone? Or do I need to source a switch with more pins/ways?

here is a picture of the guts of an 1178 (modded but the switches seem to be the original ones)
https://www.gearslutz.com/board/attachments/high-end/247580d1312378909-whats-going-rate-urei-1178-a-1178_i.jpg