Info on Rauch precision amplifier

Hi there, I have got a Rauch DVT 250-s. Does anyone have an instruction manual for one of these? i would like to use it in bridge mode but I don't know which output or combination of outputs to use for bridge mode, I'm using the binding posts if that helps. I have had a look round for info on these and have had no luck. Basically it's been sitting on a shelf in the garage for years, last time i remember it been used was about seven years back. Fired it up last night just to blow the dust out of it!! Any info. would be greatly appreciated, cheers

I coulnd find any info on them for you. The best i could find is on the link below on page 225, hope this helps a little...

books.google.co.uk/books?id=Ma7q ... q=&f=false

Cheers for that Mr. Bee smiley20 . Are they really that old.....wow. I landed up just using one channel to power a full range wedge. I'd forgot what a great sounding little amp it is. Some of the lights didn't seem to be working anymore, but it chucked the sound out in a very pleasing manner! Cheers again for the reply, much appreciated!!

there are a few guys on here that are well into amp design etc, they may have or be able to get more info for you, and also help in fixing them bulbs that dont work....

Stacey from Marquee INSTALATIONS had some of these back in the day. Very nice. Seem to remember spares were non existent though

The Rauch 250s is a very good sounding amplifier.
I recently rebuilt one to run my mids.
They are very heavy due to having 2off 1KVA transformers inside!
The 250s is 550W per channel into 4 ohms so 1100W bridged into 8 ohms.
To bridge the amplifier:- Signal into the left hand channel only, Select bridge mode on the rear selector switch,
Speaker +ve to left channel +ve binding post, and speaker -ve to right hand channel +ve binding post.
Technical data for the Rauch amplifiers is available from Ben Duncan Research.
There were a few different circuit revisions during the years that they were sold.
Later ones are less likely to blow up spectactularly if the outputs are shorted out!

A 2KVA transformer of the same type will be smaller and lighter than 2*1KVA transformers as well as being more efficient and having less voltage drop under load.

Having seperate xformers for left and right only reduces crosstalk to the extent that the amplifier stage is transmitting power rail voltage fluctuations to the output terminals. And if it is doing that to any significant degree, then you're going to hear rectified mains all over your lovely music.

I suspect that the double mono layout is a legacy of the earlier versions. These used schematics based very closely on the Hitachi mosfet application notes, and did not have a CCS on the input differential pair.
This can cause a lot of crosstalk with a shared PSU.
Later versions have a CCS on the input pair, a driver stage for the mosfets after the VAS, and protection zeners for the mosfet gates.
I think that a lot of the performance of these amplifiers has a lot to do with the robust 2 X 1 KVA PSU, 4 X 10,000uF caps and the layout/cooling of the mosfets. Later versions also had a high slew rate, and effective RF input filtering.
I can confirm that they do sound superb if recapped. I have a 500W Rauch DVT50s (single transformer) recapped with BHC ALS30 resevior caps and Elna silmic signal caps, I use it for my HI-FI.

Hi Martin, thankyou for the info regarding bridge output......great stuff. I was thinking of selling the Rauch as i use lightweights now but I think I'll keep it on the subs bench. It's like part of the family now. Cheers mate. smiley20