nothing much but a switcher

whipped this up today. I'm too poor for Igor's spify monitor control room box
and I can't stand those flimsy pro-sumer attenuators.
My boss gave me a 1-3out switcher with these cool old relays to throw in.
Hacked them all together with a 10K stepped attenuator after input for volume
(I think its valued for -70dB in 22 steps, all Vishay SMD resistors.) and a mute (EAO).
I'll take for a spin tomorrow:

cool.

Cool build 
One thought is that I'm not sure about the relay type you use there, it looks like power relays. You might be better of with smaller ones, probably sealed and with gold plated contacts. If you browse relay tech specs you need to look for small signal capabilities. I don't know the correct english terms for this unfortunately, something like minimum switching voltage. With power relays you might have corroded contacts sooner or later, causing bad connections.

Michael

Thanks guys.
Well, it sounds great (ie: transparent) and everything works as it should.
I had an old painton winkler attenuator that was wired for ~-40dB as variable pad before my amps
but it was old and on it's way out. This lets me run the amps hotter too.
Also, I have my cheap old computer speakers hooked up now too.
Great to have multiple monitors again.

The relay's are top-shelf and yes old.
I was given the 6V PS for the relays and relays, themselves, all wired as a 1in X 3out switcher in an old project box,
so this is more about recycling for me. They really are top notch quality as far as I can tell, and all
I had to get was: case, attenuator, some switches and the 1/8" panel mount mini-plug for my computer speakers.
Tho this box gives me ideas to design a PCB, I think it would be pretty simple.

Also, I might like to add a pair of meters (and corresponding driver board) and a MONO switch eventually.
I'm just over loaded on research right now as it is.

Happy to finally have a proper 'volume' knob.

Cheers!

Hey Stitch,

That's awesome! I have been thinking about something like this for a "center section".

You mention that it's a 1 -> 3 switching device. Have you set it up such that you are able to have 1,2,or3 outputs active (paralleled) at the same time? Do you find that having multiple outputs active affects the sound (ie; paralleled load impedance)?

Best,
j

Nice Work!

Nice work stitch-o!

I've got a whole bag of NOS relays and have been meaning to do a nice versatile switching box like this for eons.  You may have given me a little inspiration! 

Are those old AMF -Potter relays? 

Thoose relays look like the ones i found in my Eela broadcasting mixer, been thinkin of using them to build a relay switcher like this.

Anyway nice build!

Hi peoples!
Thanks for all the input:

@0dbfs - I have it wired now all separate and such. The chicken head knob is attached to a 3 pos lorlin switch
which sends the 6V signal to a given relay. I guess I could wire some sort of switch that opens multiple relays at the same
time, but I never really got having lots of monitors happening at once thing....aside from it being really extra LOUD.
My mains are a pair of old DMT series II that get plenty loud as it is. Plus I would imagine, as far as true monitoring, there would
be some phasing issues of some sort or another if there were multiple loud monitors happening at the same time, playing the same stereo program material.
The one cool thing I do have wired up is; I sent a mult off the output of the attenuator that goes to the mini-toggle on the front panel and then to a stereo mini-plug on the back, so I can have my pair of small crappy computer monitors AND the Tannoy's going at the same time, but also mute the mains very easily with the EAO switch (cuts 6V to the relays)...but the Tannoys really are louder than heck....
oh yeah, build it!!

@Lasso - I honestly don't know! I have to wire a new power cable today so I'll check it out.
When you look inside of them they are really stunning, design and crafted wise. In fact, I'll see if I can get a few close-up pics of them and
post them. They definitely put those dinky Omrons to shame as far as their 'built-like-a-tank'-ability.

@EJE2005 - I have these old TAB talkback micpres that have mini versions of these that I used. They are COOL!
I'm a sucker for the clear case where you can see everything work as you zap it with V's.
I have to say again, it was NOTICEABLE how better my monitors are playing now. I attribute this to quality parts.
Is Eela kinda like the Tore Seem or Tweed stuff?
Yes, build many switchers  ;D

@ Plumsolly, 3nity, et all - thanks doods!
This is the place, and you are the people, that made it happen.

I'm debating making up a simple PCB with modern parts for this box, with a couple added things.
For like 350 bucks, one could have a really high quality monitor controller/switcher thingy I think.
Don't know who would be interested tho...

CHEERS and thanks!

Looking very nice. If you happy with this, me happy too.

I'm too poor for Igor's spify monitor control room box
and I can't stand those flimsy pro-sumer attenuators.

Click to expand...

Regarding passive attenuator and 10k...
Let me tell one story from my life.
Israely people dream is invent something great and live from money earned on patent.
About a year ago, one guy proudly brought his DACT-based controller to my lab,
and told me this is the best controller his ears heard, and we have to make
gigatones of money together (he wanted me to desigh box and manufacture these CRM's).
I was silent during the test and just gave him to listen some 24/96 files
(my soundcard is Lynx2)....
We both don't have best ears on this planet, but heard little degradation in resolution,
especially at higher frequencies, at 10k DACT stepped attenuator and 3 meter cable,
monitors were Adam S3A, btw, my lab is poorly acoustically treated.
CRM built from kit sounded way cleaner.

I'm debating making up a simple PCB with modern parts for this box, with a couple added things.
For like 350 bucks, one could have a really high quality monitor controller/switcher thingy I think.

Click to expand...

The math is....$150 difference?
I am not so reach to buy cheap things
I understand you're proud with this build which looks really nice,
but...if you tell about $150 difference...dunno

The Maestro!
Hi Igor, big fan here.
FWIW: my 350usd est is all inclusive (rack case, all the parts, etc)
and the version I want to build of your incredible box is double that including case, et al.
Trust and believe I poured over your CRM build costs for months
before admitting to myself that the finances to build one were down the road.

Eventually, I will be giving you a wad of money for many, many of your boards
but, alas, as of now, it is merely gear porn on a website for me.

I will, happily, take an endorsement deal tho!!!

Cheers and thanks for checking out my silly box.

Your math is wrong, the actual difference is: kit +Purusha box+power supply less than USD540 (approx; as euro changes)... your kit target price is USD350....probably plus shipping....
I'd say the difference is closer to $150, but not twice!!!!
as here is the option to save on kit ordering parts by yourself (not much) and box diy.
Anyway thanx for...anyway
Quality-wise, it is better to have 3-5 resistors in audio instead of whole string of 21..22,
what actually happens in case of switch stepped attenuators.
At the middle of attenuator, -15...-40 db, where is the working range for monitors, in case of
rotary switch attenuator, audio passes 10...11 resistors from top and 10..11 to ground.
In case of 1-2-4-8-16-32 RELAY attenuator, at WHOLE range,  audio passes twice less resistors...
(at least, as for example at -32 audio passes only two resistors, and worst case is maximum attenuation
where it is less important than at NORMAL range).
(and relays have sealed contacts, it is pure winner agains best switches which has a tendency
to catch dust and smoke from air, Elma needs to be cleaned once a year in normal studio);
I think this is important point, as well as my attenuator is BALANCED.
Well, my point was just to say my attenuator actually CHEAPER than yours
performance, quality and money-wise.
The rest depends on taste. I love your box as well, looks nice.

Lovely build! 

thumbs up...

Igor said:

+Purusha box+

Click to expand...

This is where mine would get pricey.
I want a Pete case, no dis on Purusha,
but Pete's cases are bordering on works of art and, consequently, pricier than a Purusha.
Have you seen HIS CRM case?
WHOA GAWD, its awesome!!

I know that the actual CRM kit price is completely reasonable (an absolute steal, if you ask me) for the design and
engineering involved. Your numbers are correct.
If I didn't want the Pete plate, which I do and will gladly, thankfully and happily
save my pennies and nickles to fork over for.

I can't even argue tho.

I understand your attenuation concept.
Now I REALLY have to find some funds to build the CRM.

Cheers and thanks for the inspiration!

@Radiance - Thanks dood! Lofi is nice sometimes.
All my other builds, I really strive to make look proper in a proper studio environment.
I'm vain like that I guess.

Cheers!

Cool! You always welcome. Yes, I understand your point about case,
anyway, you can ask me for .cdr file and order front/back/controller's faceplate
from Shaeffner.

stitch-o said:

Igor said:

+Purusha box+

Click to expand...

This is where mine would get pricey.
I want a Pete case, no dis on Purusha,
but Pete's cases are bordering on works of art and, consequently, pricier than a Purusha.
Have you seen HIS CRM case?
WHOA GAWD, its awesome!!

Click to expand...

Obviously I have missed this, but who is Pete?

What do his cases look like?  Pics?

Cheers,

Rob

rob_gould said:

stitch-o said:

Igor said:

+Purusha box+

Click to expand...

This is where mine would get pricey.
I want a Pete case, no dis on Purusha,
but Pete's cases are bordering on works of art and, consequently, pricier than a Purusha.
Have you seen HIS CRM case?
WHOA GAWD, its awesome!!

Click to expand...

Obviously I have missed this, but who is Pete?

What do his cases look like?  Pics?

Cheers,

Rob

Click to expand...

Sorry, I get casual.

Pete=Grand Master Audio

and, here is the drool:
http://www.groupdiy.com/index.php?topic=32157.0

Anyone tried the stuff from this guy: http://stores.ebay.de/jimsaudiostore ? I haven't tried it, but it looks good and is very cheap (and I'm not related)!

balanced stereo volume control

http://cgi.ebay.de/Resistor-volume-control-128-steps-stereo-P1-7-balanced-/320514044301?cmd=ViewItem&pt=LH_DefaultDomain_0&hash=item4aa020318d

unbalanced stereo volume control

http://cgi.ebay.de/Resistor-volume-control-128-step-stereo-unbal-P1-7-/220585917226?cmd=ViewItem&pt=LH_DefaultDomain_0&hash=item335bf1fb2a

Input switcher:

http://cgi.ebay.de/stereo-audio-channel-input-selector-board-kit-/220497959345?cmd=ViewItem&pt=LH_DefaultDomain_0&hash=item3356b3d9b1

http://cgi.ebay.de/stereo-audio-channel-input-selector-assembled-/320487325694?cmd=ViewItem&pt=LH_DefaultDomain_0&hash=item4a9e887ffe

Lots of other interesting looking stuff there as well...

Michael

Michael Tibes said:

Anyone tried the stuff from this guy: http://stores.ebay.de/jimsaudiostore ? I haven't tried it, but it looks good and is very cheap (and I'm not related)!

balanced stereo volume control

http://cgi.ebay.de/Resistor-volume-control-128-steps-stereo-P1-7-balanced-/320514044301?cmd=ViewItem&pt=LH_DefaultDomain_0&hash=item4aa020318d

unbalanced stereo volume control

http://cgi.ebay.de/Resistor-volume-control-128-step-stereo-unbal-P1-7-/220585917226?cmd=ViewItem&pt=LH_DefaultDomain_0&hash=item335bf1fb2a

Input switcher:

http://cgi.ebay.de/stereo-audio-channel-input-selector-board-kit-/220497959345?cmd=ViewItem&pt=LH_DefaultDomain_0&hash=item3356b3d9b1

http://cgi.ebay.de/stereo-audio-channel-input-selector-assembled-/320487325694?cmd=ViewItem&pt=LH_DefaultDomain_0&hash=item4a9e887ffe

Lots of other interesting looking stuff there as well...

Michael

Click to expand...

That stereo control graveyard looks WICKED!
I might have to do a set of edits...

I bought M6 (2SK170/J74 cascode NJW0281G/NJW0302G) power amplifier kit
and other funny goods from this seller some time ago,
still not assembled the amp, but liked the seller...very cheap and looks nice,
there are 4 output transistors on each pcb, but kit came wit 4 outputs instead of 8,
anyway, it was mentioned in description. I plan to run these amps on +/-50V,
and there should be some "surge spare"...so, I just bought transistors and gave
best possible feedback to seller.
I don't think potentiometer (CV to micro-controller) is best idea...
anyway, should work with proper algorithm.
Idea: to change control voltage when passing from one speaker/source to another, i.e.
"level trim" implementation
It does not have an indication of level...anyway, worthy to try,
and...imho, final price will be same as CRM kit