kgst

[kevin gilmore]

Birgir will be building the T2's. I am just going to watch.

 

smaller version of my attenuator board, definitely want to see this.

if you make it surface mount only, then you can shrink it a fair amount.

 

The one knob control is definitely one of the better ideas.

[Kerry]

It must nice to have a Birgir for that

 

I've used these relays, G6KU-2F-Y-DC4.5, controlled by the MAX4821EUP in another project.  Very simple circuit and works perfectly.  The relays are much smaller than the original ones.  Going to all SMD parts would help a bit as well.

[kevin gilmore]

how do you drive bipolar single coil relay with single switch to ground?

[spritzer]

We will do a competely SMD attenuator as Í'm not going to assemble them... 

 

I'm also in charge of parts procurement.    If everything I've bought turns out to be real then I'll have parts for at least 50 T2's... or even 100.   

[Kerry]

I used two pins per coil.

Here's the tech note I followed:

http://www.maximintegrated.com/en/app-notes/index.mvp/id/3288

That's a lot of T2's in the wild

[kevin gilmore]

the amb method. trouble is they dont switch as fast that way.

should be ok though.

[Kerry]

The nice thing with the maxim driver is that I can set all of the pins low/high with one set instruction. It is programmable via a 3 bit address. I'm using an expander to control the address and set/reset. I've designed it so I can control two drivers with one expander, so two expanders and 4 drivers per channel.

I've been setting one relay at a time, which is the same as I was doing with the original boards.

I think I can get each channel to about 4" x 1.5". I'd like to see them mount one to the other. If we offset the relays this should work fine. Total dimension for balanced would be about 4" x 1.5" x 1".

Edited December 28, 2014 by Kerry

[Kerry]

I finally got the HV caps and the PS up and running.

 

 

 

The voltages look good including bias and pre-reg voltages.

 

I mounted the transformer and board to a temporary wood cutout that I milled.  Fit looks good.

 

 

 

The wiring is nice and neat...

 

 

 

Here you can see the transformer in the steel case mounted to top plate (wood for now)...

 

 

 

So far so good

Edited December 31, 2014 by Kerry

[guzziguy]

I'd say really good!

[headinclouds]

Yes, great work Kerry.  Very satisfying for you I trust.

 

Hope it sounds great too.

[n_maher]

Nice work, Kerry!

[Laowei]

Beautiful work Kerry. Immense envy here.

[kevin gilmore]

I actually think I can get a balanced step attenuator with those relays in the same size

as the original, all 16 relays. But a human is unlikely to ever be able to assemble it.

[Kerry]

Thanks - and yes it does sound great.

Kevin - Are you thinking of doing two columns and continuing to use both sides? Could be interesting. It would be nice if it could be soldered by hand too. Maybe trim down the control area a bit too.

[kevin gilmore]

yep 2 colums and both sides. you might as well put it all on one board because

of the size of the drivers determines the minimum width

if you solder all the resistors first, then possibly the inside row of pins on the

relays could be hard to get at.

[Kerry]

I've done the test fit for the amp section as well.  Here's a better approximation of what it will look like. 

 

From underneath (Excuse the mess of wires.  I'll fix those up once I'm happy with the fit)...

 

 

 

Here's a shot from the top of the amp...

 

 

 

I've just been listening for the past hour.  Sounds great

 

EDIT:

 

PS. Happy New Year!

Edited January 1, 2015 by Kerry

[kevin gilmore]

but but...  its upside down.

 

anyway

 

http://gilmore.chem.northwestern.edu/atten2stereobal.jpg

 

2.05 x 3 inches

 

but only 2 layers and still have to add or change the drivers

Edited January 1, 2015 by kevin gilmore

[Kerry]

I think it sounds better upside down

 

I see you did a lot of work on the board since last night.  I love it

 

I noticed the serial interface for the drivers.  That really simplifies the board.

 

This will fit perfectly in my build.

[kevin gilmore]

3 hours total

 

6 shots of various vodka's

(new kickass Russian/French restaurant with 50 different vodka's)

http://dekarestaurant.com/

 

and after generating the netlist, its still correct.

 

scary

 

The nice thing is this way you can drive all 32 relays at the same exact time.

but unless you can calculate relay position, a lookup table is necessary

 

board file posted, needs checking

Edited January 1, 2015 by kevin gilmore

[luvdunhill]

Kerry, would it be possible to get ahold of your 9-pin pattern? Or hole diameters and outer circle radius and angles?

[chinsettawong]

Really nice work Kerry.  You really amaze me everytime I see your build. 

 

Happy New Year!

 

Wachara C.

[headinclouds]

I have been running in my build and it sounds better than the first - really very pleased.

 

 

I put a heat-sink across the middle and bolted the current sources to that so it runs cooler.

 

 

 

 

[cetoole]

Very nice!  Details on the case?

[Laowei]

Very beautiful build Geoff. Eye catching aesthetics. Polished and modern look. I know it sounds great, asI have your boards.

That heat sink is giving me ideas...

Thanks for making your PCBs available to all. The KGST is spoiling me.

[headinclouds]

My own design; 3mm anodised aluminium alloy panels, thick machined FP.  Knob turned by me, Ring illuminated mains switch by me.

 

My original design was a little more ordinary, the style was the input of www.incredibledesign.co.uk

Edited January 15, 2015 by headinclouds