Maximum input level X-Can V3

[bonesinc]

First of all, I would like to state that this is my first post on these boards. So, thank you for having me here.

Currently I'm in the process of buying an X-Can V3 from a local retailer in The Netherlands. For the last days I've been listening to an X-Can V3, borrowed from one of the employees of this retailer.
I like the X-Can a lot, so I'm definitely going to buy this desktop headphone amplifier.

I have a question about the maximum input level the X-Can can take without damaging it or drastically reducing the lifetime of the valves.

First some information about my setup.

I'm using the DAC of my Behringer Ultramatch Pro SRC 2496. The outputs of the Behringer are balanced, so I made some XLR to RCA cables, wired for unbalanced output to an amplifier.
The thing with the Behringer XLR outputs is that they have a professional output level. Meaning +4 dBu, instead of the -10 dBu of consumer electronics. I made some in-line attenuators to reduce the output level and they are working fine.

My question is the following:
Can I connect the outputs of the Behringer directly (so no attenuators) to the inputs of the X-Can without worrying about damaging it?

I would have asked Musical Fidelity directly about this, if only I could find there e-mail address on their website.

Matthieu

[bonesinc]

So, I guess nobody knows..?

[rickcr42]

I have a question about the maximum input level the X-Can can take without damaging it or drastically reducing the lifetime of the valves.

not only can you not hurt the valves with even an extremely high audio signal yours ears would be the only things hurt from the clipping so would be enough to force you to back off on the volume control.It is more running out of headroom than it is how much voltage the input can take

My question is the following:
Can I connect the outputs of the Behringer directly (so no attenuators) to the inputs of the X-Can without worrying about damaging it?

absolutely but you may find you are using the volume control at an extreme attenuation level to keep the amp from overloading which by being at the bottom of the pot rotation will be in the area where left/right channel tracking is at its worst.

If you are looking for the best bang for the buck solution for the hot voltage level a resistor pad is fine but if you want the ultimate in performance then you may want to look into a "Backwards J-Box" (second schematic in the pdf file) step down transformer.Converts the 600 ohm balanced "hot" signal into a single ended liner level consumer input

www.jensen-transformers.com/as/as081.pdf

[rickcr42]

www.jensen-transformers.com/as/as012.pdf

[bonesinc]

If I'm looking at the schematics correctly, am I right to assume that there is no external power supply needed? If that is the case, I just might buy one and built it in a shielded box.

The main disadvantage of a transformer over some simple resistors is that they are more easily picking up external noise. Correct?

To be honoust. I just went the cheap way to try if it would work.

Thank you.

[bonesinc]

Or, even better, I might put it in the Behringer itself. Adding some RCA outputs on the back as well. No doubt there is space for it in this thing.

[rickcr42]

If I'm looking at the schematics correctly, am I right to assume that there is no external power supply needed?

Correct.Totally passive device.

If that is the case, I just might buy one and built it in a shielded box.

Yes.Build this one :

www.jensen-transformers.com/as/as012.pdf

Small shielded box,mount the transformers with can capacitor clamps bolted right to the chassis but damp the actual transformer to chassis contact point with a small piece of sorbothane or other vibration damping material (foam,anything that prevents metal to metal contact) then damp the transformer itself by putting a wide rubber band over the whole thing.May be overkill but so cheap and easy to add in better to just add in up front.
For the signal wiring you can use and good #24 or smaller solid wire (silver or copper,your choice ) for the signal wiring,twisted,but for the PIN-1 connection solid copper #18.This is a ground connection so needs to be a low impedance contact.Also you want a heavy dutty toggle for the ground lift not a wimp mini-SPST switch and again for a low impedance contact.Keep all this as short as possible and nail it right to the chassis by using a combination of bolt/nut/lock washer/solder tab plus if the "box" is anodized or painted scrath the area clean so the lock washer bites into the metal making a solid contact.

The main disadvantage of a transformer over some simple resistors is that they are more easily picking up external noise. Correct?

The main advantage here is total isolation of digital ground noise and a true "Balanced" to "Unbalanced" interface due to the nature of the windings and a true negative gain created by the ratio of the windings.The only thing you need to watch is you impedances so what you connect it to needs to be 10K ohm or greater at the input.

To be honoust. I just went the cheap way to try if it would work

nothing wrong with resistors if done right.This is just better.

Thank you

My pleasure.was waiting for someone else to answer but seeing that was not happening weighed in

Or, even better, I might put it in the Behringer itself. Adding some RCA outputs on the back as well. No doubt there is space for it in this thing.

Workable only if you keep the lines VERY short.The secondary impedance of the transformer places certain limitations on how you connect the output side with those mainly being low capacitance cables and short runs.If the Behringer will be within two feet then cool.more than that and you risk upper octave attentuation when the R/C of the cables interact with thew transformer output creating a low pass filter

If you are up to it here is some reading on the topic :

Balanced/Unbalanced

Transformer FAQ

a bit more advanced

Seminar

Audio Transformers

[rickcr42]

You are trying to make one of these (or buy one for $210 )

www.jensen-transformers.com/pc2xr.html

www.jensen-transformers.com/datashts/pc2xr.pdf

www.jensen-transformers.com/datashts/pc2xr_usr_man.pdf

[bonesinc]

Thanks for the links Rick.

Since I have had an education in electronics I have forgotten most of it. Except for the things I cared for. But with my background I think I can get the idea of the articles to which you posted the links. Perhaps a bit of headscratching every now and then but that's ok.

And thanks again for chiming in while no-one else has. I guess not many of the members here had to deal with my issue on hand.
To give you an indication, I also posted this question on Head-Fi after I got no responses here in the beginning, and out of the (probably) thousands of members I had just one response from someone who directed me to this forum.

But....it's all fine now, since I have my answers.

Cheers,
Matthieu

[rickcr42]

To give you an indication, I also posted this question on Head-Fi after I got no responses here in the beginning, and out of the (probably) thousands of members I had just one response from someone who directed me to this forum.

Probably someone who knows I hang out here now rather than camping out at headfi

good luck,

Rickmonster

[uofmtiger]

This is my first post. I just bought an X-can V3 with Little Pinkie V3. I have a SRC2496 and love the sound with my main system. I am thinking about buying another one for the X-can to use between it and my computer.

Will something like this work:

www.samash.com/catalog/showitem.asp?ItemID=26797&ovchn=YAH&ovcpn=Yahoo+SSP&ovcrn=26797&ovtac=PI&AffiliateID=330

[bonesinc]

Hi uofmtiger,

I looked at that thing quite a while ago and asked a technical engineer at the broadcast station I work for. He told me that most 'cheap' transformers are not performing very wel at this task. Let's say, not really suitable for hi-fi.
That's the main reason I went for the resistor option in the first place. Just to see if it works. And it does. I might build someting with the Jensen transformers in the future, when my funds are allowing me.

So, if you want to try the Samson box I will be very interested in hearing your opinions on how it performs.

P.S.
Your review of the SRC 2496 is the main reason I bought it myself.
Thanks for that, for I'm really happy with it.

[uofmtiger]

bonesinc said:

Hi uofmtiger,

I looked at that thing quite a while ago and asked a technical engineer at the broadcast station I work for. He told me that most 'cheap' transformers are not performing very wel at this task. Let's say, not really suitable for hi-fi.
That's the main reason I went for the resistor option in the first place. Just to see if it works. And it does. I might build someting with the Jensen transformers in the future, when my funds are allowing me.

So, if you want to try the Samson box I will be very interested in hearing your opinions on how it performs.

P.S.
Your review of the SRC 2496 is the main reason I bought it myself.
Thanks for that, for I'm really happy with it.

I am glad that you found my review to be useful. I love the Behringer and it works great in my main system.

I may just get the Emu 0404 USB for my office/X-can setup. At this point, I would need to upgrade the sound card, buy another SRC2496, and the Samson. It would be cheaper, easier, and more predictable to do an all-in-one solution like the E-mu.

I was wondering about the Samson, but I could not find a review anywhere. I am glad you saved me from going down that road.