X Can V2 output?

[Crispy]

Hi There.

Mike has finally persuaded me to join the gang.

As a new member I am hoping somebody out there can help me solve a problem with the output of my X Can V2.

I'll try to keep it short so here goes.

After extensive modifying of my X Can I decided that it was far superior than my X Pre amp. So I decided to replace the X Pre and use the X Can as a pre amp as well as a headphone amp.
Here is the problem!
The output from the X Cans go direct to my XA200 mono amps. The volume is extremely loud even with the volume set at OFF - you just cannot listen to it.

I adjusted the gain for listening through my headphones by replacing resistors R107 & R207 with Holco 69K8 0.2w resistors to get the perfect listening volume as described on one of the tweaks pages. (Thanks Sandy K)

Can anybody advise me how I can reduce the output volume from the Cans to a level that is the same as listening through headphones?
I am hoping it is a simple case of replacing a couple of resistors but would not know where to even start looking as I have very limited electrical experience apart from a bit of soldering.

Thanks in advance for any help.

Crispy face

[mrarroyo]

I still do not understand why you are doing this but ... get a 1/4" to RCA cable and buy a set of in-line attenuators (3 dB or 6 dB or 12 dB) like: www.amazon.com/Harrison-Labs-Line-Level-Attenuator/dp/B0006N41B0

[PinkFloyd]

Jul 8, 2011 22:19:04 GMT mrarroyo said:

I still do not understand why you are doing this

X2

[Crispy]

Thanks for the advice mrarroyo.

I did think about using attenuators but thought it would be better to calm the output internally with a couple of resistors. If this is not possible then attenuators may have to be the way to go.

I want to use the X Can v2 as a headphone amp and a pre amp like the X Can V8p so that when my wife is watching TV I will listen through headphones & when there is nobody in the house I will listen through my HI FI at quite a loud volume - Thank God for detached houses.

Or do I sell my X pre, X can v2, X psu and buy the X Canv8p? Anybody got one - if so I would be interested to to hear what you think to the sound via both headphones and HI FI.

[dejanm]

You might try to solve the problem by exchanging resistors R116 (3K3) and R117 (8K2) with larger values. Simply experiment with different resistor values on these positions. It should give you larger level of attenuation.

Another posibility is to use another pot - maybe 100K or even larger. It will be though not so easy to find one that will fit properly into the unit.

Saying all this, I would advice you to go for separate preamp and keep this baby as it is ...

[Deleted]

Saying all this, I would advice you to go for separate preamp and keep this baby as it is ...

That would be my thinking too, but let's see what Frans has to say .

[Deleted]

I missed the most obvious option.

Mod the Xpre so it betters the Xcan...

The real question is are you using the line out RCA's ?
If so the volume control will do nothing at all nor will the sound 'alter' as the line in (source) is directly coupled (hard wired) to the line out from the line in RCA.
The line in and line out are simply exactly the same (acc to the schematics I found) and it really doesn't matter if you use the line in or line out as input as they are the same.
IF you are using the output of the amp (6.3mm Jack) I suggest to simply put small trimmer potmeters between it and adjust to the desired level.
If you are really picky about potmeters measure the potmeter values and replace with fixed resistors.

The schematics are not accurate b.t.w.
I expect R108 to be 100k instead of 100R

[Crispy]

Thanks guys for the recent advice.

If solderdude is correct that the line in & line out are directly coupled then I am guessing that I cannot use the X Can V2 as a pre amp the way that I would have liked to. I am a complete beginner at this electronics lark but learning fast.

It does not take a genius to realise that the volume control will never alter the output via the line out and using attenuators will attenuate the sound but I will not be able to turn the volume up or down. The output from my X Ray CD player is going to go direct to my amps with no control over the volume?

Mike, can you tell whether this assumption is correct as you are the king of the XCans.

If my assumption is correct then I will probably upgrade my X Pre as solderdude suggested. The X Pre and X Cans are very similar internally and I will just have to find a way of adding a headphone jack so that I can listen through headphones when I need to. The only other alternative is what I mentioned before and buy a X Can V8p which was designed to work as a headphone/preamp.

[Deleted]

There is also the option of disconnecting the output plugs of the Xcan and adding a cap and 2 resistors per channel and solder that to the unconnected output plugs.

[Deleted]

crispyface

Frans is correct. The Line IN and Line OUT jacks are hard wired together, so your assumption about being unable to control volume is correct.

[mrarroyo]

I thought the OP wanted to use the 1/4" headphone out as a pre-amp not the rear pass through RCA's.

[Crispy]

After reading again the reply from solderdude I had another look inside my Xcan to see if I can have one last attempt to do what I want.

My plan is to disconnect the input/output RCA's then bend the pins of the L & R channels of the output RCA - resolder back into place connecting all three pins on the input and only earth on the output.

I will then take wires from the underside of the L & R channels of the Jalco headphone socket and solder to the now bent and disconnected L & R channels of the output RCA.

My thinking is that the volume pot controls the headphone socket so it should now also control the output through the RCA's, the output volume is perfect through my headphones so it should also be about right through my amps, if not a couple of resistors connected in line of the new wires should correct it.

Can anybody see any obvious flaws to this plan that I do not know about - like I said before only new at this modding game but having fun.

Kepp you all posted on the outcome - by the way nice melons mrarroyo!

[Deleted]

I would solder a 100 Ohm resistor to R114 (at the leg where it joins R113 and R115).
Solder the other leg of that resistor to the + of a capacitor (10uF/50V polar or non-polar)
The - of that capacitor I would connect to a resistor (10k Ohm) and connect the other side of this resistor to ground.
Similar to the current circuit R114, C110, R119.
From the - of the new capacitor connect a wire to the, now unconnected, output RCA's.

This has advantages over connecting directly to the HP socket.

[Crispy]

I read your reply a bit late solderdude - after my little experiment.

The experiment partly worked in that it was fabulous as a pre-amp and dog turd through headphones - can't win?

Any chance you can do me a little diagram on the method you suggested as it did not quite make sense. It only says connect 1 wire from the capacitor to the unconnected RCA - surely it needs two one for Left one for Right?

Thanks again for your help.

[Deleted]

The procedure is described for 1 channel only. (the Rxxx and Cxxx are for 1 channel also)
You need repaeat exactly the same for the other channel.
The ground pins can stay connected.
This way the HP section remains untouched and the output section will be independent of HP's being inserted at the same time or not.

If you need assistance You need to post pics of top and bottom PCB side.

[PinkFloyd]

The schematics are not accurate b.t.w.I expect R108 to be 100k instead of 100R

Hi Frans,

R108 is actually 220K

Mike.

[Crispy]

Hi Frans,

I get it now.

Because I have practically no electrical experience whatsoever, could you advise me which channel is which?
When I take the signal from R114 is this Left or Right channel?

Where do I take the signal from for the other channel - guessing R113?

Would you advise me to do this work from under the PCB or from the top - seems very little room to work from the top? Also found a couple of Panasonic FM 50v 120uf capacitors in my limited bits box - could I use these instead of 10uf? No problem if I can't as I need to shop for some resistors anyway.

Thanks again, you have been a great help so far.

[Deleted]

yes you can use the 120uF but in this case you should lower the 10k resistor to 2k2.
The rest (100 Ohm and connection method) remains the same.

I will need top (componentside) and bottom (solderside) pics of the BOTTOM board (Perhaps Mike has some posted already) to show it must be done.
Have never seen these things IRL.

It would be logical to call the same part in the other channel = R214 ... don't really know.

Since R114 has 2 legs, 1 = connected to Cx10, you will need to extract the signal from the other leg of Rx14 (the one that is connected to Rx13, Rx15, Rx08 and Cx07)
That is the actual output of the amp.

If you found that leg of R114 and (R214 ?) you have the point where to solder 1 leg of the 100 Ohm resistors to those points.
Both channels need 1 resistor of 100 Ohm connected to Rx14 (the proper leg that is).

Those 2 100 Ohm resistors then go to the +pins of both 120uF caps.
The - legs of these caps need to go to the output RCA's.
Parallel to these output RCA's (from centrepoint to the ground terminal) you will need to mount a 2.2kOhm (anything between 1k5 and 4k7 will do, but need to be the same value for both channels.

Then you are set to go.

Don't know if 1xx is left or right... in the worst case scenario you have left and right swapped and this can easily be corrected.

[Crispy]

Just to update you all.

Been busy working, but finally got the chance to have another go.

After removing the wires from the output RCA's and the headphone socket, I decided to double check everything was OK through headphones again - UTTER CRAP!!.

I decided to re-solder the headphone socket and when I de-soldered the earth all the pad disappeared up the tube - I had found my problem. Re-soldered the socket back into place and checked again - Perfect.

As I like to keep things simple, I decided to put the wires back from the headphone socket to the RCA's.

This finally solved my problem and although I have only had time to listen to a couple of tracks I can tell instantly that the modified X CAN V2 makes a first class tube pre-amp, it absolutely destroys the slightly modified X PRE.

People asked me why I wanted to do this? The answer is simple.
X PRE 4 inputs no headphone socket - only need one input for my X RAY CD
X CAN 1 input 1 headphone socket.

Like I said I like to keep things simple and I did not want to go - CD into X CAN into X PRE into amps.
The less in the way of the signal has to be better? - CD into X CAN into Amps.
This is why I am going to leave this set up as it is - only two oxygen free wires to carry the signal to the output RCA's.

No disrespect Frans, you have been a great help to me and I am sure I will need your help in the future, but unless you can convince me otherwise there are too many components in the signal path to try your method now.

By the way R114 is RIGHT channel and R214 is LEFT channel just so you know for future reference - considering you have never seen an X CAN V2 in real life you are a very clever bloke.

I am going on holiday tonight but when I return I am going to make a more permanent and better routing of the cables - then burn everything with a burn in disc for a good 24hours and then have a proper listen - can't wait.

I will let you all know how it sounds.
Thanks again everybody.

[Deleted]

No disrespect Frans, you have been a great help to me and I am sure I will need your help in the future, but unless you can convince me otherwise there are too many components in the signal path to try your method now.

Actually there will be an equal amount of components in the signal path.

The way you have connected it now, and when you plug in a headphone AND use it as a pre at the same time the sound from the pre out will be altered/affected because of the headphone connected which loads the amp in a non-linear fashion.

With the described mod you get:

a: an equal amount of parts in the signal path.
b: a decoupled path from headphone and pre out (they do not influence each other)
c: Smaller caps are usually ascociated (subjectively) to have better SQ.

Ever figured out how many parts (from the studio microphones right to the output of your CD player) are in that path already ?


Missing the ground in the headphone socket will bring bass-less weird mono music without lead voices and only the echo's and 'off center' instruments.

[Crispy]

Back off holiday

Had another listen for about half an hour before I couldn't stand it any longer, must have been listening through rose tinted glasses last time. The sound was very hard and tiring.

Whilst I was listening I decided to plug in the headphones to see if the sound was the same through them - instant cure sound back to normal. So Frans you are correct that the sound from the pre out will be altered/affected when used this way (not that I would want to).

So I am going to take your expert advice and try the method you suggested, but just to check that I have understood your method correctly could you please look at the attached diagram and advise me whether this is correct or not?
The only difference to your suggested method is the resistors / capacitors would be connected near the rear of the unit as there is more room there, but I will have another look before I make up my mind

Thanks again Frans.

(Look on page 2 for revised component diagram)

Attachments:

[Deleted]

Seems about right.
It must be connected to the Rx14 leg that is NOT connected to Cx10.
I recommend (rather insist) that the 100 Ohm resistor is mounted as close as possible to Rx14 and from that point a wire going to the capacitor.
This to prevent instability of the amplifier.

In case the output voltage is too high for the power amp (you can hear noise) the resistor values might need to be changed, but first try these values.

[Crispy]

My hats off to you Frans, your a genius.

I was a bit nervous about doing the modification your way because I could not understand the signal going from the cap to the RCA and also to Ground . I need not have worried everything was fine.
I managed to fit the resistors and caps close to where you suggested, there was enough room with a little bit of imagination. I will see if I can get some photos to post?

My initial listen was a couple of familiar tracks and I was a bit disappointed because the sound was again a bit hard especially female voices, but I could tell that this time the sound was right and I put the hardness down to new components needing burning in. So I left a burn in disc feeding the cans for a couple of days, then had a re-listen today for about an hour. WOW!!

It took me a good half an hour to get used to the completely different sound stage mainly thrown backwards and not in your face - a bit like Naim amps and very clinical, then the foot started tapping and a big cheesy grin came to my face - this is was what I was aiming for when I started the project.
I could go on and on about the improved sound but I won't bore you to death and I am sure the sound will continue to improve.

I am now one happy bunny.

The X Cans V2 cost me £65 off E bay and I have not kept a tab on the cost of modifications but estimate another £65. So for £130 (approx) I now have a stunning first class Pre - Headphone amp. I will now sell my X Pre amp on E Bay and hope to get somewhere in the region of £80 - £100.
This will mean I have upgraded to a far superior amp for approx £50.

If anybody reads this in the future who is considering using the X Cans as a pre-amp/headphone amp and asks was it all worth it - the answer to that is a very big YES.

I have no electrical experience and do not consider myself to be a good solderer but I have always been willing to have a go. A little bit of research on the internet and a bit of practice on some old PCBs and I was confident enough to tackle this project. If I can do it anybody can?

So I would just like to say a very big thank you to everyone who helped me along the way, especially to Frans for the technical help and to Mike who supplied me some difficult to get parts always with a kind word.

Thanks again

Chris

[Crispy]

I started to get a crackle on the left channel and decided to investigate.

I completely rewired my work with some Evolution OFC audio cable - it was more flexible than the original Kimber OFC cable that I used.

I also found out that I had connected my interconnects the wrong way round because the markings had worn off. This meant my original assumption that R114 was Left channel was wrong.
I can now confirm that R114 is RIGHT and R214 is LEFT channel.

I also found a few iffy looking solder joints so I re-soldered them just for good measure.

Some people use a 20mm hole cutter to ventilate the top of their XCans.
I could not bring myself to mutilate my casing so decided to drill 2mm holes in the top eight grooves at a spacing of 50mm 60mm and 70mm and then at 95mm 105mm and 115mm from the rear of the casing. These small hole are barely noticeable once gone over with a black permanent marker pen.

I then drilled 4mm holes in the bottom side grooves at the same spacing of 50mm 60mm 70mm and 95mm 105mm and 115mm from the rear of the casing. Again these are barely noticable once gone over with the black marker pen and stood up the correct way.

The idea was to let hot air out of the top holes while cooler air would be drawn in through the bottom holes.

The question is does it run any cooler? The simple answer to this is YES and the good news is the wife hasn't even noticed them YET!

Another burn in and listen - Everything back to normal except it sounded even better than before.

Just sold my X-Pre on E-bay for £113 so I have upgraded for approx £20, the whole project has been very worthwhile and invaluable for the knowledge I have learned.

Picture showing 4mm holes drilled in the bottom grooves.

Attachments:

[Crispy]

Picture showing 2mm holes drilled in the top grooves.

Attachments: