Is my cross-feed circuit working? Kindly help.

Hi all,

This is my first post.

THE NEED FOR A CROSS-FEED CIRCUIT
=================================
Rhythmbox is my favorite player. Just that it doesn't have any cross-feed plugin. I tried Foobar2000 with WINE(because I'm on Ubuntu Linux) and with bs2b and cross-feed plugins. I couldn't really tell a difference, but there was a subtle one. I wanted to see if a hardware implementation of cross-feed would improve the sound quality. I also wanted to get back to using Rhythmbox very badly, with cross-feed, and see what it was like and whether the hardware implementation would be different and better from the software version of those afore-mentioned plugins in Foobar2000

THE BUILD OF A CROSS-FEED CIRCUIT
=================================
So I decided to go the hardware route and build one. I went out and bought the necessary components and soldered together(rather shoddily) a cross-feed circuit based on the enhanced bass Linkwitz design with a bypass switch. Actually two bypass switches, as I couldn't find a 3-way 4-pole switch(I bought two 3-way 2-pole switches). I got the instructions from http://www.rock-grotto.co.uk/crossproject2.htm. I thought it would be good for a first-time-after-a-long-time DIY project, which it was.

THE PROBLEM
===========
I wired up everything. But I'm not sure it's working. Either I'm in bypass mode or the effect is REALLY subtle. It may just be that the bass is a bit muddier/stronger and that audio separation between channels is not that pronounced. It may be, or that could just be silly old me.

PLEASE SUGGEST YOUR SOLUTIONS
=============================
(1) Please tell me how I'm supposed to go about measuring the outputs(and possibly the inputs) with a multimeter to ascertain that the cross-feed circuit is working, if necessary.

(2) I would like to know that when I push up to the top on a 3-way switch, are the center and top positions connected? Or are the center and bottom positions connected? Because then, I would know whether I am in bypass mode or not.

(3) Also I would like to bring to your attention that the supposed "bypass" mode has a lot of attenuation and distortion. Could it be that the "bypass" mode is actually the cross-feed mode?

MORE OBSERVATIONS

==================

1 - "bypass" mode,

2 - "cross-feed" mode,

0 - off,

(LR)

(02)When I turn off the switch responsible for the left hand side IO(and leave the right IO switch on in "cross-feed" mode), I get only a stronger signal on the right earcup and only on the right.

(20)When I turn off the switch responsible for the right hand side IO(and leave the left IO switch on in "cross-feed" mode), I get a mild signal on both channels(left and right). I thought this the right side should be turned off completely, but that isn't the case.

(22)When both switches are turned on in "cross-feed" mode, I get the full standard sound with very SUBTLE characteristics as mentioned above(bass muddier/stronger, and less stereo separation).

(01)When I turn off the switch responsible for the left hand side IO(and leave the right IO switch on in "bypass" mode), I get only a weaker signal with more treble than bass on the right earcup and only on the right.

(10)When I turn off the switch responsible for the right hand side IO(and leave the left IO switch on in "bypass" mode), I get a mild signal with more treble than bass on both channels(left and right). I thought that the right side should be turned off completely, but this isn't the case, similar to (20).

(11)When both switches are turned on in "bypass" mode, I get a very echo-y effect with a massive drop in bass and quite a drop in volume. This mode may have to be amplified as setting the volume too high on my laptop causes too much distortion.

THANKING YOU
============
If you've made it this far, then thanks very much for your patience. I'll be glad to post pictures of my build upon request. I am new to electronics and don't know the theory and circuit analysis stuff, but I may pick up a book and learn. I just soldered with instructions from that afore-mentioned site(http://www.rock-grotto.co.uk/crossproject2.htm) and I used what appear to be unpolarized capacitors.

Please do respond with your solutions and suggestions,
Siddharth.
 

This ain't gonna be pretty...

I'm sorry I couldn't find the macro settings on my camera.

Quote:

Originally Posted by Spacehead 

please provide pictures of your circuit both sides. 

I have posted the pictures taken from my phone. I took them at a resolution of 640X480. I couldn't find the macro settings on my phone camera though. As a result the close-up pictures are slightly blurred. The post containing the pictures is awaiting moderation. Until then, have a look at the album in my profile. Many thanks.

Testing whether my replies are still under moderation.

Quote:

Originally Posted by Spacehead 

please provide pictures of your circuit both sides. 

Here we go folks. I couldn't find the macro settings on my phone. Neither are the pictures nor the shoddy mess of a circuit, going to be pretty:

Quote:

Originally Posted by Fred_fred2004 

...I used 2 x 2PDT and wired them as per the diagram and throw both switches together

...its very suble I use a 1k test tone

...The circuit as published is very good and does not give any adverse effects

 

cheers

FRED

Regarding the 2 X 2PDT switches, well that's the configuration I used.

I agree, it's quite subtle. Sorry, I don't understand what you mean by 1K test tone. Is it a sound file? If possible, please give me a link to it.

Yes, the technical soundness of the circuit design was never in question. It's only my own technical abilities that I doubt. ;-)

Quote:

Originally Posted by the_equalizer 

Indeed, you don't really need to measure with you DMM. Just use some hard panned recording for example The Beatles' "Here Comes The Sun". These recording starts with an acoustic guitar hard panned to one channel.

 

Test a). Play the start of the track and turn the crossfeed on and off. As someone previously posted, you'll hear the guitar move slightly to the center and forward. Very subtle.

 

Test b) Play the start of the track and remove the can where it is sounding, leaving the other one on. Turn the crossfeed on and you'll hear the guitar very low on the other headphone.

 

cheers!

Test a) With a direct headphone connection, and my balance set 100% to the right through Sound Preferences, I get a little bit of sound of the guitar through the first 15 seconds.

Test b) With the headphones connected through what should be the "cross-feed"(22) circuit, I get... the same thing.

Test c) With the headphones connected through what should be the "bypass"(11) circuit, I get... a much lower volume sound of the results of tests a and b.
 

Quote:

Originally Posted by tangent 

I'll second the "pull one RCA" test.

Sorry I am not sure what RCA means. But if you refer to the left and right individual sockets, then I have to inform you that I'm using headphone sockets. The pictures ought to clear things up.

Thanks all once again for your help.

Sorry I can't get through a detailed response with pictures as my replies are still under moderation.

I would like to close this thread and mark it as solved.

I have found out that I've been using the wrong-mode all along. I've mistaken the bypass mode for the cross-feed mode and vice versa.

My signal has to be amplified if I'm to use the cross-feed effect, as there's a bit of loss in bass and volume.

Hence a bass-boost CMoy seems to be the way to go next.

Thanks to every one here who contributed.

Cheers guys!