FS: M605A and M605C Audio DAs Tested

[Alex Hempel]

Hello everyone, I purchased five WBS audio DAs from a recycler. I have two M605As and three M605Cs.  One M605A is missing a fuse cap, but otherwise there are no flaws in any of them beyond scuffs and light scratches.

I cleaned and tested each one and they all work flawlessly. The manuals say they are good for 18dB of gain maximum, but I set each one to 20dB during testing and they still had more gain left in them. 

The build quality is really solid. They have nice potted Hammond power transformers and the internals are beautifully laid out. I also have original manuals, which are in great condition, for both models. 

Here is a link to a Google Photos folder with the M605C manual pictures. Anthony, feel free to add these to your manual folder. Unfortunately I don't have a big enough scanner to do them properly.

Please shoot me an email if you have any use for these. More than happy to ship them to wherever and supply pictures. Thanks!

[Geoffrey Doane]

Alex,

Did you terminate the outputs with 600Ω (or 150Ω for the 605C) when testing these?  If not, you'll get 6 dB more gain than expected.

The inputs are bridging, and are probably best left that way for most applications in the present era.

We had a supply of used 605As (decommissioned from control rooms) for doing various odd jobs at my old radio station.  They were a good design with plenty of drive capability and low crosstalk between outputs (unlike the older 600s), and since the power supply was self contained, it was practical to use them as singles (with an appropriately wired connector).  As I recall the 650 (with a neon pilot light instead of LED) had a more limited gain range, but were otherwise quite similar.  If these have been sitting in a rack for 20-30 years, cooking away, they could probably benefit from new capacitors, but they are easy to work on since the PC board unplugs from the chassis.

Geoff Doane, Halifax, NS

[Alex Hempel]

Ah, good spot -- I didn't load them, so that explains the higher-than-expected gain. I usually work on home audio gear so I think of everything as bridged.

[Anthony Kuzub]

Thanks Alex!

It's preserved here: https://drive.google.com/drive/folders/1sIRrT5Bv965X4FKf8b0Pm0czVG-vN8Eh?usp=sharing

Anthony

--
The WBSps.ca is run by Canadians who appreciate Well Built Stuff
 
Manuals: https://drive.google.com/drive/u/2/folders/0B0yR0b5T78SKczBIcDgzZkstUjQ
 
Photos:
https://drive.google.com/drive/u/2/folders/0B0yR0b5T78SKd2JnQzlrckY2bWM
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