The No.1 Website for Pro Audio
 Search This Thread  Search This Forum  Search Reviews  Search Gear Database  Search Gear for sale  Search Gearslutz Go Advanced
Seeking info on very old, very well built German Compressor Modular Synthesizers
Old 15th January 2013
  #1
Here for the gear
 

Seeking info on very old, very well built German Compressor

Looking for some help in sourcing some information about this very old german compressor we have at our studio. Unfortunately non of us speak german, so we haven't had any luck wiring it up and getting any signal out of it. The wiring is incredible, and the components look excellent so we're eager to try this thing out! All we know is what the casing says. Looks like the manufacturer is Rohde & Schwarz. model: BN 1601. Begrenzungsverstärker?? Any Help or information would be hugely appreciated! Thanks
Attached Thumbnails
Seeking info on very old, very well built German Compressor-bergrunzenvergerstarkerorsomething.jpg  
Old 15th January 2013
  #2
Lives for gear
 
Jamie Mac's Avatar
Rohde und Schwarz are a broadcast company that started in the 1930's, and still today a manufacturer of measurement equipment.
Begrenzungsverstärker is german for Limiting Amplifier.
Other words I can spot are:

Abgleich = alignment
regelspannungs verstärkung = voltage gain
Kompensat. Spg = probably some sort of make up (compenstation?)
betriebspegel = operational level (underneath it says fein, simply meaning "fine")
Begrenzungg I : limiter I
Begrenzung II : limiter II
Ohne begrenzung : no limiter

not more I can say, I'm sure its quality stuff, the stuff they make nowadays is top notch measuring equipment. maybe you could shoot them a mail, they might have an archive of information just waiting for you!
It does look really old, so you're potentially looking at a lot of time and money getting it up and running or even never get it working again. Or spending it and not liking its sound

Rohde & Schwarz - Rohde & Schwarz
Old 16th January 2013
  #3
I would love to see what's inside if you get a chance to take some gut shots.
It looks a very serious bit of kit to me. I love this sort of era pro equipment because its usually so well made.
Old 16th January 2013
  #4
Gear Addict
 
ioaudio's Avatar
 

That's a Rohde & Schwarz U23 limiter - a serious piece of hardware woth lots of heavy iron in it.
Rohde and Schwartz U 23 compressor - YouTube
Old 16th January 2013
  #5
Here for the gear
 

That's all excellent info guys, thanks alot! I've emailed the manufacturer, I'll let you know what they say. I'll also take a "gut shot" for ya there Bassmec
Old 16th January 2013
  #6
Gear Nut
 

Here is a link to the service manual, unfortunatly in german:
http://www.google.de/url?sa=t&rct=j&...,d.bGE&cad=rja
Best Tobias
Old 16th January 2013
  #7
Here for the gear
 

Quote:
Kompensat. Spg = probably some sort of make up (compenstation?)
Should be "Kompensation Signalpegel" or word-by-word translated compensation signal level, which would indeed be make up.
Old 16th January 2013
  #8
Lives for gear
 
leaper's Avatar
 

Yes, like previously mentioned, you've got yourself a U23 limiter.
Varimu technology. I had 2 and found them very hard to set up properly.
They looked so cool but acted in quite a heavy handed, sometimes unpleasant fashion. Tonally they tended to suck out the bass and had quite a trebly sound.
I'd be interested to see what you think.
Both mine were then modified into a pair of Vacuvox CL2 compressor/limiters. Simply the best compressors I've ever used. I've posted many glowing reports about those vacuvoxes. They were phenomenal.
I regretfully sold them to fellow gearslut SIXTWOFOUR
So my take on it is that the U23 is an interesting limiter with restricted functions/ uses while the Vacuvox modification turns it into one of the most seriously killing compressors ever: varimu, variable threshold, ratio, attack, release, input and output gain, selectable HPF on sidechain (I also asked for an additional insert point into the sidechain so that a graphic EQ could also be inserted). These changes turned it into a machine that could enhance any source... anything: drums, guitar, bass, voice, wind instruments, sub groups, master bus (I had 2). Plus it could be used as one hell of a preamp with either compressor in the chain or out.
PM me if this modification is of interest to you and i'll send you some pics and a manual.
If SIXTWOFOUR is reading this maybe he'd like to add something about this comp?
Old 16th January 2013
  #9
Lives for gear
 
nickelironsteel's Avatar
 

this is a U23 (TYPE ABR - BN 1600/BN 1601) Begrenzungsverstärker (1953-1954) by Rohde & Schwarz. its using 3x EF804S, 2x EAF 42, 1x EB 41, and 1x ECC 40 tubes, the fairchild design is very or lets say too similar to these . Berry Goedemans @ The Sonic Playground.nl makes (or made) the mods, hes on gearslutz as BigBang.Quality compressor, but didnt live up to the high standards of the IRT.

you could buy those for a few hundred euros in the 90s.

i have just bought a rhode and schwarz phase meter type PZN. 5U tall HUGE meter, like 20 tubes inside and built to alst forever.
Old 17th January 2013
  #10
Lives for gear
 

These guys know how to make it work: SonicWorld Audio Shop
Old 17th January 2013
  #11
Here for the gear
 

Thanks so much to everyone for the comments and info. Big thanks to Hop.Sing for the manual, that is AWESOME. With that we'll hopefully be able to get it up and running! I popped the hood and took a few pics of the guts. Will let you know how it turns out in the next few days here. Thanks again!
Attached Thumbnails
Seeking info on very old, very well built German Compressor-u23-above.jpg   Seeking info on very old, very well built German Compressor-u23-bottom.jpg   Seeking info on very old, very well built German Compressor-u23-top-left.jpg  
Old 17th January 2013
  #12
Lives for gear
 
brianellefson's Avatar
Damn ... that thing is cool. I hope you guys get it fired up and running nicely.
Old 18th January 2013
  #13
Lives for gear
 
Marcocet's Avatar
That's a hell of a find. I've been looking for one for ages.
Old 18th January 2013
  #14
Gear Nut
 

What a beautiful thing...really well built... like the old Telefunken v86/v87 record and replay amps we use with our m10a tape recorder. Same rack format, all those screwdriver pots and a construction that screams QUALITY. If it sounds like it looks, you are a lucky guy.
It seems to be modified to xlr plugs and a new mains plug already, some of the cabeling looks new, too. What is the problem with that thing?
Old 18th January 2013
  #15
Lives for gear
 
Vintageidiot's Avatar
That looks as gorgeous as any gear I have ever had the great fortune to gaze upon.....
Old 18th January 2013
  #16
Here for the gear
 

Hop.sing, yes you are correct, it has already been modded for xlr's and an iec power connector. The problem is, once it's all hooked up with signal passing through, it doesn't seem to be engaging the compressor. The bypass setting works fine, audio passes through without any signal loss, but with the compressor turned on it loses about 90% of the signal an seems to have no effect on the meter. Obviously we've tried the various settings, make-up gain etc, but still can't get anything out of it. We have a hunch that it might have something to do with the last two pins on the output connectors. We think they might need to be jumped together. There's evidence of a previous solder on those pins.
Old 18th January 2013
  #17
Gear Nut
 

Hi
Bypass seems to bypass the electronics (true bypass, so to speak), no wonder it works. The last pins on the output connector used to be the mains connection and have been replaced by the iec connector, I do not think, that that is the problem.
You should probably take that compressor to an experience tech, since the problem could be anywhere in the signal chain.
There are some things you can try yourself.
Maybe swapping tubes to known working ones, but the ef804s tubes are expensive and rarely fail, being high quality longlive tubes (rated at least for 10000 hours), Reseating the tubes is something to try, corrosion on the sockets can be a problem. Inspect for loose cableconnections, burnt resistors, bad solderjoints, but other than that, there is not much you can do, you would need at least a scope and quite a bit of experience with tube equipment repair.
Tobias
Old 22nd January 2013
  #18
Here for the gear
 

Yep, we saw that too. Those last two pins are indeed the old power hookup. The bypass works with the power off, so it is a "true" bypass. Thanks for posting the link to the manual. The schematic was very helpful. We surmised that the power transformer does not have a tap for US voltage. It needs a step up transformer to power the thing correctly. duh. We felt kind of dumb. We are hoping that is all it needs. We are getting a couple 100 watt IEC in and out step up/down transformers from FRY's so we will let you know how it goes!
Old 22nd January 2013
  #19
That's funny. I do hope though you can get it running. Exchanging those big capacitors could be impossible...
Old 22nd January 2013
  #20
Here for the gear
 

Yes and the wiring in this thing is such a work of art, I'd hate to modify anything else.
Old 22nd January 2013
  #21
Gear Addict
 
studiosale's Avatar
 

gorgeous unit!
Old 22nd January 2013
  #22
Lives for gear
 
nickelironsteel's Avatar
 

looking for a pair for ages
Old 22nd January 2013
  #23
Lives for gear
 

Hi
If the big electrolytics have failed I believe one of the 'tricks' is to carefully take the guts out of the old aluminium can and fit a new replacement inside, as they are usually considerably smaller than the old types (better manufacturing methods). You would then 'seal' the bottom end up somehow to complete the deception.
Be aware that there is a possibility that the 'first' big electrolytic after the rectifier is likely to have significant 'ripple' on it and may run warm, a factor to be considered if you are 'rehousing' a new cap.
Matt S
Old 22nd January 2013
  #24
Lives for gear
 
dandeurloo's Avatar
Wow, I bet that sounds really great. What tubes are in it?
Old 22nd January 2013
  #25
Lives for gear
 
SIXTWOFOUR's Avatar
Leaper. Glad you are doing well! The Vacuvoxes are the BEST compressors I own. Took almost 10 years to find. I also own a stock U23 that is not as useable as the Vacuvoxes but does sound great. The previous owner of my U23 had it teched by Andreas Grosser. BTW: The prices of U23's have gone through the roof last year. If there is any other info you need feel free to ask.

Quote:
Originally Posted by leaper View Post
Yes, like previously mentioned, you've got yourself a U23 limiter.
Varimu technology. I had 2 and found them very hard to set up properly.
They looked so cool but acted in quite a heavy handed, sometimes unpleasant fashion. Tonally they tended to suck out the bass and had quite a trebly sound.
I'd be interested to see what you think.
Both mine were then modified into a pair of Vacuvox CL2 compressor/limiters. Simply the best compressors I've ever used. I've posted many glowing reports about those vacuvoxes. They were phenomenal.
I regretfully sold them to fellow gearslut SIXTWOFOUR
So my take on it is that the U23 is an interesting limiter with restricted functions/ uses while the Vacuvox modification turns it into one of the most seriously killing compressors ever: varimu, variable threshold, ratio, attack, release, input and output gain, selectable HPF on sidechain (I also asked for an additional insert point into the sidechain so that a graphic EQ could also be inserted). These changes turned it into a machine that could enhance any source... anything: drums, guitar, bass, voice, wind instruments, sub groups, master bus (I had 2). Plus it could be used as one hell of a preamp with either compressor in the chain or out.
PM me if this modification is of interest to you and i'll send you some pics and a manual.
If SIXTWOFOUR is reading this maybe he'd like to add something about this comp?
Old 9th March 2013
  #26
Lives for gear
 
Bigbang's Avatar
 

Vacuvox mod

Just to let everybody know that we still do the Vacuvox mod. Actually it is more of a rebuild [with new faceplate, extra switches, pots, rewiring, etc] then just modifying the U23. It took 2 years to develop this rebuild, with extensive testing/listening sessions as the guideline.

It takes 4 weeks of work to do that job. Contact me if you are interested in a rebuild.
Old 25th February 2015
  #27
Here for the gear
 
B-A-R's Avatar
 

Hello all.. i had a pair of these a few years ago. An ebay score, they needed some love. I sent them to Martin Eich in KY. He re-capped them, and from what i remember there's some diodes that need to be updated for safety. He also made a panel for me with external attack/release settings, as well as input/output attenuation and stereo linkability.
It took a while and few bucks, but man, those things were the sweetest, fattest comp/limiters i've ever used. They don't quite do the Fairchild pumping thing, but they reminded me more of a very transparent LA-2A on steroids. They would just make anything put through them sound bigger but not in an aggro way. The vocal chain was usually mic/V76/U23-Genex. Also sounded fantastic on acoustic guitar.
I tried to have them modified into VacuVoxes, but they people that did those mods said they don't do them anymore, so that's why i sent them to Martin. (A very reliable and solid german gear tech, highly recommended! CustomAudioLabs' vintage equipment website! )

I'd give him a holler if you still haven't sussed out the issues..

Cool score!

B
Old 25th February 2015
  #28
Here for the gear
 
B-A-R's Avatar
 

Quote:
Originally Posted by Bigbang View Post
Just to let everybody know that we still do the Vacuvox mod. Actually it is more of a rebuild [with new faceplate, extra switches, pots, rewiring, etc] then just modifying the U23. It took 2 years to develop this rebuild, with extensive testing/listening sessions as the guideline.

It takes 4 weeks of work to do that job. Contact me if you are interested in a rebuild.

Oops. just saw this. When i had my two i wanted them converted/modded and i think yall told me one guy did them and wasn't doing them anymore :(
Old 25th February 2015
  #29
Lives for gear
 
Bigbang's Avatar
 

Quote:
Originally Posted by B-A-R View Post
Oops. just saw this. When i had my two i wanted them converted/modded and i think yall told me one guy did them and wasn't doing them anymore :(
That's a pitty, because we never stopped doing the Vacuvox mod.

Vacuvoxes are used by Madonna, Terry Britten, Oasis, Michael Brauer, Mark 'Spike' Stent, Paul Weller, Merlin Moon and many more.
Old 17th August 2016
  #30
Here for the gear
 
allarts's Avatar
 

You still do this mod's? I have 2 U23's, curious about the price for the mod. Are you in Germany?
Topic:
Post Reply

Welcome to the Gearslutz Pro Audio Community!

Registration benefits include:
  • The ability to reply to and create new discussions
  • Access to members-only giveaways & competitions
  • Interact with VIP industry experts in our guest Q&As
  • Access to members-only sub forum discussions
  • Access to members-only Chat Room
  • Get INSTANT ACCESS to the world's best private pro audio Classifieds for only USD $20/year
  • Promote your eBay auctions and Reverb.com listings for free
  • Remove this message!
You need an account to post a reply. Create a username and password below and an account will be created and your post entered.


 
 
Slide to join now Processing…
Thread Tools
Search this Thread
Search this Thread:

Advanced Search
Similar Threads
Thread
Thread Starter / Forum
Replies
mattianlaseppia / So Much Gear, So Little Time
6
MichaelPatrick / Mastering Forum
3
rodhmos / So Much Gear, So Little Time
4

Forum Jump
Forum Jump