PlanetZ forums - scopeusers.com

Hi

I have a Pulsar II Plus, and while all my INs are balanced by my mixer, my speakers will only accept a unbalanced signal...
I cannot find any commerical product that will deal with this effectively, so I have decided to use a cable whereby the negative singal is connected to the ground. I already use this to connect a TC electronics Fireworx in the FX loop of my mixer...

Does anyone have a better idea?
Will this cause any problems?

Please help, i love the card and wouldn't want to damage it or blow my speakers.
Also, if I use a Y cable, would I be able to connect 2 soundcards to the same speakers and hear both outputs if either of them play?

Thanks
Andrew Valentine

Did you try using the analog out's in your Pulsar2?

On 2004-08-01 07:38, cleanbluesky wrote:


Please help, i love the card and wouldn't want to damage it or blow my speakers.
Also, if I use a Y cable, would I be able to connect 2 soundcards to the same speakers and hear both outputs if either of them play?

Thanks
Andrew Valentine

You can't do any of these things.
You can easily find a box to get unbalanced outs from a balanced signals.

Y cables is the most absurd thing to think.. sorry, you are going to f#@* up sound, speakers and everything. If your cards are both creamware you don't need to do it, as the sw environment can be routed on one card for outs, but I guess there is another brand card. in that case if you don't need it strictly remove it, If you need it and it's a good brand, you can route physical outs of a card into physical ins of the other, or, better, provided that you need also that box to unbalance signals, get a little mixer with unb and bal ins, connect your cards there and mix to the speakers.

But don't do anything you said!

Thank you for your good advice... Can you recommend a small mixer that has bal and unbal INs with unbal outs?
Why would connecting both of them with a Y cable be such a bad idea?

The reason I don't want to route it is that Scope would have to be on all the time for me to hear the second soundcard, and I wouldn't be able to hear system sounds or whatever if I were not in Windows... I would rather just connect them all up physically after they have left them computer...

Would balanced to unbalanced leads from only the Pulsar card straight into my active speakers be okay?

There is absolutely nothing wrong with making your own cables.

However be careful. As DeejaySly warned me a couple of months ago, IC-based balanced outputs can easily be shorted out by tying cold to ground.

If your mixer is transformer balanced then it's fine to strap cold to ground. Otherwise just leave cold "dangling" at the speaker end -- i.e. connect hot to hot and shield to ground, but just snip the end of the cold wire.

Also I'm assuming your speakers are active?

Does your Pulsar card have balanced I/O? Mine (Z-Link) only has unbalanced. If yours has balanced, you will definitely not want to connect cold to ground. Do the same as above -- connect hot to hot and shield to ground and leave cold dangling.

Cheers,

Johann

I have already done it, I checked out various resources on the net, most notably a good .pdf from http://www.film-tech.com/manuals/TN99060401.pdf that covers installing theatre equipment between unbalanced and balanced and also a lot of articles (try searching yahoo for "connecting balanced to unbalanced equipment" or some such and you will find audiophiles are not alone in the connection problem) and found that many suggest that not connecting the negative on a balanced signal can damage equipment and make the +ve signal unreliable. But I have also read the same of connecting it. I judged the best guide would be the pdf as it seemed in-depth and detailed different types of balanced connection. I guessed that my Pulsar II plus didn't have psuedo-balanced outputs so decided to link the -ve to the earth on the OPPOSITE end of the cable (the speaker input end). I also made a Y cable where I have my standard stereo out from my Soundblaster Audigy ZS Plat Pro and Left/Right outs from my Pulsar II Plus connecting to the same socket on my speakers. It seems to work fine, althought the PulsarII is quieter than the Audigy. In future I may just by a small mixer, it seems appropriate. Yes, the speakers are active...
Since Creamwares technichal specifications don't seem to go far beyond explaining that my board has 6 SHARCs and that SHARCs are good, I'm not sure what method of balancing my outputs offer...
Would be nice to know, and also to know whether my -ve to ground was appropriate. At least before the card blows...

On 2004-08-01 12:01, cleanbluesky wrote:
... Why would connecting both of them with a Y cable be such a bad idea?...

an output stage is designed to drive one single input stage. Resistance and capacity have an influence on frequency and phase of the output signal.
If you connect a second out parallel (with the Y) each of your output stages gets an additional load (it's neighbour amp), which will corrupt the original signal.
The amount depends on the design of the amp stages, but it's inevitable.

Alfonso is right. You really shouldn't do it because the output stages of both cards probably won't have the same 'level' and a slight difference can cause a significant flow of current.
Again, this depends on the design of the amp stages, but better be safe than sorry.
It may work now, but could fail any time.

The output of your Pulsar is top quality, definetely. Don't spoil it with a cheap mixer.
Do you need the sound of both cards simultaneously, i.e do you record from the Audigy AND have it for Windows sounds ?
Otherwise a cross-switch would be better if Pulsar is turned off.

cheers, Tom

<font size=-1>[ This Message was edited by: astroman on 2004-08-01 17:52 ]</font>

http://www.film-tech.com/manuals/TN99060401.pdf

The document gives good advice, although I much prefer docs that back up their arguments with explanations. There is far too much "magic expertise" in this industry, and far too many self-proclaimed wizards.

There are great books and websites out there that go into the physics behind balanced and unbalanced connections. Personally I don't understand why the above doc talks about "frequency instability" when you leave an unbalanced "cold" wire dangling. What a load of hooey.

On the other hand your signal is 1/2 as loud (6 db lower than a balanced signal) and you do re-introduce the old potential for ground loops.

you will find audiophiles are not alone in the connection problem

After some of the stuff I've seen recently, I think audiophiles are idiots. Seriously. Take a look at the threads in the "Off Topic" section on double helix power cords and "silver rock signature knobs".

I guessed that my Pulsar II plus didn't have psuedo-balanced outputs so decided to link the -ve to the earth on the OPPOSITE end of the cable (the speaker input end).

Your Pulsar is definitely not transformer balanced. Transformers will not fit on PCI cards. The question remains: is it truly an electronically balanced differential output or "pseudo-balanced". I've looked around and never figured out what "pseudo-balanced" means. I would be happy to be edified.

If you've tried it and it works then I say go with it. You can spend all your time calculating equations, or you can go on empirical experience. Although studying all this stuff is fun and worthwhile, I still believe in experience over theory.

BTW if you want to build a simple mixer you can buy a cheap op amp, a couple of pots, a breadbord, and some wires at your local electronics store; or order something pre-built from Radio Shack for about the same price ($20).

Cheers Cleanbluesky,

Johann

Thanks for your advice guys. When I meant 'cheap' I meant v.small (enough to fit at back of computer) but a good make... I think Behringer gear is okay but has reliability problems. Just check the b-stock section at http://www.dv247.com (English site) to see the amount of Behringer gear that has been returned.
My main problem with my Y cable idea is now that the volume differs so I will just get a small mixer to fix this (more cables, more plugs ).
I think that 'Audiophiles' do have some issues with spending more time on esoteric setups (double-helix semi-electrolyte magnetically-responsive homogenically-transducive power cables) than on watching what they are actually recording... but I don't know a word that means 'person-who-likes-audio' that doesn't also translate to 'person-who-likes-audio-too-much'.


Can anyone suggest a nice, tiny mixer that would do the job and stabilize audio levels for me?

Mackie Tapco, yamaha also have very very small mixer, or even probably better for your actual need, the samsom control room.

very cheap they are...