Does this look right?

Dustin Haug · 22nd September 2002, 10:45 PM

I'm gonna run a BOSOZ unbalanced in/balanced out and hopefully someday feed a nice pair of Aleph 2 monoblocks. Anyways what I'm concerned with is how I terminated the negative input, I did a search and I believe this is what Nelson recommended.

The other main question is with regards to the portion of the circuit in the red box. I'd be using this pot as an input level trim with one of these (dual gang) on each input either before or right after the switching relays. Am I correct in thinking that this would work? I'd like to be able to use only dual ganged pots in my circuit for simplicity's sake (trim, gain, and volume). Any other suggestions for tweaks I'm getting real close to ordering up the parts.

Thanks!

moses · 23rd September 2002, 12:06 AM

I don't know about everyone else, but that image doesn't show for either one of my connections, probably because GeoCities blocks external sites from linking images. You should probably just use the board's upload feature for adding a image.

skaara · 23rd September 2002, 12:13 AM

Voume controls must be after the relays. And its better for you to use them on the output. because you will be lowering noise too at low volumes..

Dustin Haug · 23rd September 2002, 01:08 AM

My bad on the image. This time it should work.

Dustin Haug · 23rd September 2002, 01:14 AM

skaara,

Why is it that volume controls have to be after the relays? The pot on the input will be used to adjust for the different input signal levels depending on the sources used. To make the input signals all approximately the same level so that switching from say a CD player to a computer output doesn't dramatically change the volume.

I'm still gonna have my main volume control on the outputs. As discussed in this thread.

balanced volume control

Peter Daniel · 23rd September 2002, 01:24 AM

If you are using separate pot for each input it doesn't matter where you place the relay. If you put the realy before the pot, the pot might load your source but i don't think it's a problem.

Dustin Haug · 23rd September 2002, 01:40 AM

Thanks Peter, that's what I was thinking. It seems cleaner to me to put the pots before the relays, and then I don't have to worry about anything placing an unwanted load on the source.

Does it look right how I did the negative input? I'm pretty sure it's o.k. just need some reassurance.

Peter Daniel · 23rd September 2002, 01:47 AM

The negative output looks OK. Actually you have to put pots before relays, otherwise they will all load the input of your preamp. I didn't thought about it initially.

skaara · 23rd September 2002, 08:12 AM

If you will use separate pot for each input then they dont have to be after relays

And ground the negative input..

skaara · 23rd September 2002, 08:18 AM

And if you want unbalanced in to balanced out, there will be losses on undriven side and you will have unequal voltage on + output and - output so I suggest you that you install constant current source as discussed in this thread opened by me because I had the same problem with unbal -> bal.
You have 2 options, mosfet ccs or bipolar ccs, I chosed bipolar because it sounds better.. Its wery easy, just put enough heatsinking on transistors.

http://diyaudio.com/forums/showthrea...&threadid=5558

22nd September 2002, 10:45 PM	#1
Dustin Haug diyAudio Member Join Date: Feb 2002 Location: Charleston, SC	Does this look right? I'm gonna run a BOSOZ unbalanced in/balanced out and hopefully someday feed a nice pair of Aleph 2 monoblocks. Anyways what I'm concerned with is how I terminated the negative input, I did a search and I believe this is what Nelson recommended. The other main question is with regards to the portion of the circuit in the red box. I'd be using this pot as an input level trim with one of these (dual gang) on each input either before or right after the switching relays. Am I correct in thinking that this would work? I'd like to be able to use only dual ganged pots in my circuit for simplicity's sake (trim, gain, and volume). Any other suggestions for tweaks I'm getting real close to ordering up the parts. Thanks!

23rd September 2002, 01:24 AM	#6
Peter Daniel diyAudio Member Join Date: Jul 2002 Location: Toronto, Canada	If you are using separate pot for each input it doesn't matter where you place the relay. If you put the realy before the pot, the pot might load your source but i don't think it's a problem. __________________ www.audiosector.com “Do something really well. See how much time it takes. It might be a product, a work of art, who knows? Then give it away cheaply, just because you feel that it should not cost so much, even if it took a lot of time and expensive materials to make it.” - JC

23rd September 2002, 01:47 AM	#8
Peter Daniel diyAudio Member Join Date: Jul 2002 Location: Toronto, Canada	The negative output looks OK. Actually you have to put pots before relays, otherwise they will all load the input of your preamp. I didn't thought about it initially. __________________ www.audiosector.com “Do something really well. See how much time it takes. It might be a product, a work of art, who knows? Then give it away cheaply, just because you feel that it should not cost so much, even if it took a lot of time and expensive materials to make it.” - JC

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23rd September 2002, 12:06 AM	#2
moses diyAudio Member Join Date: Aug 2002 Location: Aberdeen, SD	I don't know about everyone else, but that image doesn't show for either one of my connections, probably because GeoCities blocks external sites from linking images. You should probably just use the board's upload feature for adding a image.

23rd September 2002, 12:13 AM	#3
skaara diyAudio Member Join Date: Jun 2002 Location: Europe, Slovenia	Voume controls must be after the relays. And its better for you to use them on the output. because you will be lowering noise too at low volumes..

23rd September 2002, 01:08 AM	#4
Dustin Haug diyAudio Member Join Date: Feb 2002 Location: Charleston, SC	My bad on the image. This time it should work.

23rd September 2002, 01:14 AM	#5
Dustin Haug diyAudio Member Join Date: Feb 2002 Location: Charleston, SC	skaara, Why is it that volume controls have to be after the relays? The pot on the input will be used to adjust for the different input signal levels depending on the sources used. To make the input signals all approximately the same level so that switching from say a CD player to a computer output doesn't dramatically change the volume. I'm still gonna have my main volume control on the outputs. As discussed in this thread. balanced volume control

23rd September 2002, 01:40 AM	#7
Dustin Haug diyAudio Member Join Date: Feb 2002 Location: Charleston, SC	Thanks Peter, that's what I was thinking. It seems cleaner to me to put the pots before the relays, and then I don't have to worry about anything placing an unwanted load on the source. Does it look right how I did the negative input? I'm pretty sure it's o.k. just need some reassurance.

23rd September 2002, 08:12 AM	#9
skaara diyAudio Member Join Date: Jun 2002 Location: Europe, Slovenia	If you will use separate pot for each input then they dont have to be after relays And ground the negative input..

23rd September 2002, 08:18 AM	#10
skaara diyAudio Member Join Date: Jun 2002 Location: Europe, Slovenia	And if you want unbalanced in to balanced out, there will be losses on undriven side and you will have unequal voltage on + output and - output so I suggest you that you install constant current source as discussed in this thread opened by me because I had the same problem with unbal -> bal. You have 2 options, mosfet ccs or bipolar ccs, I chosed bipolar because it sounds better.. Its wery easy, just put enough heatsinking on transistors. http://diyaudio.com/forums/showthrea...&threadid=5558

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