[BUILD] 1176 Rev A - Back to the beginning...

[clintrubber]

[quote author="mnats"]Really? I got this page at the top of the list from a Google search:

http://www.waltzingbear.com/Schematics/Urei.html

Maybe I'll have some time on the weekend to plug a mic transformer into the front end...[/quote]
That's the one ! Thanks, this is the one I had seen before, much appreciated, I'll check why google didn't for me....

 

[edanderson]

the schematic for all of the bluestripe revisions indicates the same input and output transformers as the rev D. i've heard that some early units had a peerless input transformer... maybe that was united or maybe the users just swapped them out themselves, as seems to have happened on some older 1176s.

buliding mnats version, you'll want the type O-12 input and you'll need the special 5002 output. the hairball store is going to have both, probably by next week.

ed

 

[skipwave]

Mako, you are a DIY role model! Ed and Mike, too. Thanks for sharing guys.

As an aside, I wonder how close the UA reissue is to the original 1108. Hmmmm.

 

[dissonantstring]

hi mako,
very nice job. as always, i'm impressed by your initiative and methodical approach to each project and getting it done in such a simple, but elegant way. :thumb:

i'm intrigued by ed's idea about the signal preamp of the 1176 being utilized by the 1108 to be used as a mic pre. i've kind of researched on this and the now discontinued 2108 has mentioned that a 'then' new discrete FET signal preamp was used in the unit. alone, the original 1108 line amp has 40-45dB of gain so the 2108 signal preamp would give about 20dB of gain. i'm curious as to how much gain is in the 1176 Rev.A signal preamp section alone (sans input transformer)? i also seem to recall mr. WO'B saying a cinemag CMMI-7C (which gives about +17dB on input) was used in the 2108 (i may be completely wrong). a smaller step-up like the UTC 0-12 makes more sense, that's why i ask if you happened to know the about of gain in the Rev.A signal preamp section.

And yes, I would be interested to see if a PCB could be made from an "amputated" version of your Rev.A and yes you've damned my vow to not build another 1176 with your tantilizing Rev.A! :twisted:
i give up, but my rack is creaking at the thought of mounting one more version of 1176!!

thanks mako and ed!! :thumb:
kind regards,
grant

edit: p.s. does anyone know the specs of the original T5000 input transformer of the 1108 line amp? ed?

 

[edanderson]

the 5000 is a 1:8 with taps for higher ratios like 1:16, 1:32, etc. i don't know much more than that.

the preamp of the 1176 gives about 15db of gain.

i would recommend a higher ratio transformer than the O-12 (which is actually a slight step down) if you want to use it as a mic amp.

ed

 

[dissonantstring]

thanks for info ed!
so a 1:8 input transformer with 1108 line amp circuit and output transformer would give the original 40-45dB of gain. add the signal preamp of the 1176 (+around 15dB) and you get 60dB of gain. perfect for a mic pre.

hmmm...so mako, when were you going to get to that "amputated" preamp only version? :green:

ed,
would the same T-Pad attenuator be used on the front end before the step-up input transformer in an 1108 type mic pre or would a simple passive variable pad work? what does the 1176 signal preamp like to see for input impedance from the input transformer (since the original 0-12 was 200 ohms as the secondary - wired reverse). would a higher input impedance into the signal preamp affect the frequency response much? (sorry for all the questions).

kindest of regards,
grant

edit: 0-12 wired backwards on 1176 (right)?

 

[emrr]

[quote author="living sounds"]When you say more aggressive, do you mean this to be more in the Chandler line of things, kind of more coloured? Or is it an aggressiveness more of the VCA kind? [/quote]

I would imagine aggressive tone such as delivered by RCA BA-31/71/72, or other similar amp circuits of the origination era. In contrast to circuits like the Altec 9475A or Langevin AM-16. Nothing to do with the compression itself, I think.

 

[CJ]

Bobbin: Cosmo Corp 7063-0 (you have to cut 4 slits in each side for the leads-could only find a bobbin with 3 slits)
Lams: 24-25 EE .014 49 or 80 Ni. (haven't figured thatout yet) 27 ea. 3/8 stack
Winding Structure: 1/2 Sec-Bi-filar Primary-1/2 Sec.
Wire Size: Pri-.0045 Sec.- 0.0005 (thin!)
Turnsri.-516 Each (Bi-filar)
Turns: 2500 each 1/2 Sec. so 5000 turns total for the Sec.
So turns ratio is 1:10 from each Pri to Sec.
DCR-41 and 42 ohms each Pri, 2.4K Sec.? (meter was unstable)
Inductance: Pri-11 H. each. Sec> ? Bridge did not like this coil. Estimate from turns ratio 1000 Henries.
Leakage: 1 mH from each Pri. to Shorted Sec.- 174 pF from either Pri. to Sec.
Core grounded to 1.1 inch OD mu can
Pri. Colors: Brn-Red-Org-Yel
Sec. Colors-Grn and Blu
Shield Wire is Gry
Leads are 0.044 PVC multistrand
Each shield is soldered to 3 pieces of green magnet wire and joined to the gray wire.
There are two shields-One between each Sec and the Pri.
Starts of Pri. windings: Brn-Org
Finishesof Pri.windings - Red-Yel
The start of the inner Sec.is the splice to the outer Sec. The finish is Blu lead.
The start of the outer Sec. is the Grn. lead.-The finish is the splice to the inner Sec..

 

[mnats]

Gawd, a CJ dissection thread-stopper!

The auctions are live! Two auctions will run simultaneously:

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=250318004747
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=250318003468

All proceeds will be donated to this forum.

 

[edanderson]

don't forget that this auction is the first chance anyone will have to build a rev A, AND the proceeds go to benefit the forum. it is a pretty nice package!

ed

 

[Bryson]

[quote author="Greg"]Nice work mnats!

I have used the Blue Stripe with the LN mod added. Great compressor. Would love to DIY one.[/quote]

Both of my Blue Stripes have the LN mod added too. One has a potted module, and the other a perf board with the same type/era parts as the unit (factory?). Both have 0-12 xfmrs.

 

[okgb]

would get a couple of pre only boards if they become available
or just use the rev A for that , if that is possible

 

[ruairioflaherty]

would get a couple of pre only boards if they become available
or just use the rev A for that , if that is possible

From Mako's Rev A page here - http://www.geocities.com/m_natsume/1176_revision_a.html

"Because of the shared heritage with the 1108 microphone preamplifier and because there are subtle differences between the two designs, footprints have been designed into the limiter board to allow you to build an 1108 preamp. All you need to do is add Cx6 and Rx14 (component values are printed on the board) and stuff only the components within the "Signal Line Amp" border. Of course you will also have to add the off-board components including an appropriate microphone input transformer and provide power for the amplfier and phantom (if used)."

Ruairi

 

[okgb]

Thanks Rauiri
mako would be all over me if he saw that but
i was responding to his mentioning a seperate board
if there was enough interest , which would save buying
the whole limiter board set [ not like i don't need to finish a few first though ]

 

[mnats]

mako would be all over me if he saw that but
i was responding to his mentioning a seperate board
if there was enough interest

I saw it

I've linked to my Rev A page in the first post of this thread now so I'm taking part of the blame.

Ed is trying out the Rev-A-as-1108-based microphone pre I believe...lets see what he discovers. Maybe others are going to try the preamp thing too and we'll have some reports on the workability of it and whether or not they can sort out some of the issues others have had with duplicating the 1108...

 

[okgb]

It makes it a little uncertain whether to wait , or get a 1176 rev A for that purpose
want to respect your not collecting wish , and not waste the switch boards
and i also trust Ed to have a believable report , hmmmm

 

[edanderson]

i expect good results.  when i'm done you'll all hear about it, but don't let that stop anyone else from getting started.  we may end up in slightly different places, after all.

ed

 

[Kid Squid]

Absolutley fabulous work , chaps 

Brilliant.


Steve

 

[Rob Flinn]

Mnats,

Are you using Tantalums for the 6u8 ??    Is that what was used in the original ?

 

[orangerec]

I have a confession. I purchased one of mnats revA boards and I might be in over my head. I have built the GSSL, G Pultec and even a G1176 with great success. These projects are so well documented and I have been spoiled with this great forum and fantastic parts lists from you guys. I started shopping for parts for the 1176 revA but realized I'm a little lost with which parts to order. I have the BOM but my inexperience is confusing me with what type of caps or resistors to use. For example, at Mouser: aluminum electrolyic, polymer, ceramic, tantulum caps... Anyway, if anyone has a parts list with part numbers from Mouser or Digikey, It would be a great help. Or if anyone would shed some light on just the caps, that would also be a great help. Thanks again and I'll keep studying on my end.

-Student for life