A twisted tale about a logarithmic relay attenuator

[Nordic]

Lol Brian, we appreciate what you guys do....

Another question... Could boards be so adjusted that one can use balanced or unbalanced inputs, say, flipping a switch.

 

[BrianDonegan]

Yes, it works that way automatically. If you set it up for balanced opperation (two relay boards), single ended inputs will work fine.

 

[promitheus]

Can you guys make a PCB to adapt a Lorlin rotary switch that can switch the input with one contact and switch on LEDS with the other contact.
Something like the Aleph P would be cool where the LEDS are in a circle or line beside or above the selector knob.

 

[BrianDonegan]

Can you guys make a PCB to adapt a Lorlin rotary switch that can switch the input with one contact and switch on LEDS with the other contact.

For the attenuator or the source selector?

For the attenuator, we use a pot, not a rotary switch, so that would not work.

For the source selector (Darwin) you could do it with a single deck rotary switch. Just run GND to the switch's common, then from each position tap back to the darwin input header. Then run +5V to the LEDs+ (common) and a resistor from the switch taps to the LED-. There is no audio signal going through the switch, so no worries there, and the switch can be a cheaper unit.

 

[BrianDonegan]

So, about the kit resistors...

Russ and I have talked it over quite a bit. I am currently planning on including Phoenix MRS .6W resistrs in the kits. Here's the
datasheet.

We also discussed Dales (RN60), but they are fairly large for this board. Comments?

 

[joster]

'fairly large' as in uncomfortable, or won't fit?

 

[Russ White]

'fairly large' as in uncomfortable, or won't fit?

They will fit, but not as well. RN55s would fit better.

The Pheonix I think are the best choice.

 

[jleaman]

For this to work you have to use 2 boards right ? because it is balanced input. You'll need one board per input.?

 

[BrianDonegan]

For balanced operation, yes, two relay boards. For Single Ended, one relay board.

 

[jleaman]

For balanced operation, yes, two relay boards. For Single Ended, one relay board.

One more question. This will allow me to use regular rca in and use balanced out right. ? I'm new to this balanced stuff.

 

[BrianDonegan]

Well, you could do that, but your XLR (balanced) output will not be balanced. You would need a balanced converter to make it actually balanced (differential) output. If you are using an X-BoSoZ or something similar (which I happen to know you are ), you would want to go single-ended inoput to that (tie -IN to GND), then balanced out to the Joshua Tree (balanced) to your balanced amp.

 

[jleaman]

Well, you could do that, but your XLR (balanced) output will not be balanced. You would need a balanced converter to make it actually balanced (differential) output. If you are using an X-BoSoZ or something similar (which I happen to know you are ), you would want to go single-ended inoput to that (tie -IN to GND), then balanced out to the Joshua Tree (balanced) to your balanced amp.

So the volume pot would come after the pre-amp board right.? Not before it. I was going to design a balanced board converter but then Brian ( briangt) said to ask you and i believe he also said that your pre-amp will convert single ended to balanced for me.

 

[Russ White]

Jason, there is no volume pot in the signal path.

For a single ended source into a balanced input power amp you would do this:

SE Source --SE-> XBOSOZ -BAL-> Attenuator(2 x JT) -BAL-> Power Amp

For a singled single ended source into a single ended power amp you would do this:

SE Source --SE-> XBOSOZ -SE-> Attenuator(1 x JT) -SE-> Power Amp

-SE-> = Single ended wiring.

-BAL-> = balanced wiring.

To operate Twisted XBOSOZ in SE mode(both in and out) you simply short IN- and IN GND as well as OUT- and OUT GND.

For SE in and balanced out you only short IN- and IN GND.

For balanced in SE out you would short only OUT- and OUT GND.

Balanced in and balanced out requires nothing but wiring to the correct inputs and outputs.

Hope that helps.

 

[jleaman]

Thanks Russ. I think i gotit now. I'll keep you posted. Im on my way home in a day and will start construction on this kit i bought.

Jase

 

[lgreen]

***
So the volume pot would come after the pre-amp board right.? Not before it.
***

Correct.

Russ, why don't you revist my suggestion onPost #7 of your x-ccs-bosoz thread--

Since I am making suggestions, how about you modify the schematic and put in the vol control? The only reason is that you would then be the only one to have a full X-CCS-BOSOZ schematic with vol control, apparently since its so "obvious" no one includes it in their schematics.

Plus if you are making boards people will wonder where to hook up the vol so even if you just have some holes with a label it would be a little easier for beginners. Also its kind of odd to have a preamp circ lacking volume.....but of course its up to you.

Seems that while you are now making a very nice vol contrul people don't know where to put it.

 

[jleaman]

Correct.

Russ, why don't you revist my suggestion onPost #7 of your x-ccs-bosoz thread--



Seems that while you are now making a very nice vol contrul people don't know where to put it.

I'm sorry to cause this.

 

[Russ White]

Progress..

Hi Folks. Well the PCBs got here a few days ago, and I built an SMD version of the Joshua Tree and a through hole version with the kit .6W Pheonix resistors. I can say I like ethem both equally.

There was a small production error on botth the controller and the relay PCB which I was able to correct with an exacto knife and a jumper wire, but I had to have the whole batch remade for the kits. Not going to make you guys mod PCBs. So the kits/PCB may be delayed a week or so, but not more. They actually may get here on time.

Here is a stacked controller with the Pheonix JT.

 

[Russ White]

Here is the Pheonix relay PCB.

 

[jleaman]

Can we buy the smd version ?

 

[Russ White]

Here is the SMD relay PCB with Rhom .25W metal film resistors.