[busyx2]

Hi,
I don't recall seeing too many headphone amps that has cross feed circuit. In general, are they useful or just gimmicks?

I recalled having an old Headroom demo and I do not hear any meaningful improvement, just different. With the crossfeed turned on, imaging shifted and a bit diffused.

Tried the Foobar plug-in, and really can't tell if anything changed.

 

[GreatDane]

Crossfeed can often be very subtle. The effect or lack of will depend on the recording. I rate the Meier crosfeed at the top out of portable amps which include Xin SuperMini, HeadRoom Micro Amp,Practical Devices XM5 and Meier Porta Corda MkIII-USB.

My second favorite is with XM5.

It takes time to appreciate what a good crossfeed circuit can do because many recordings will not benefit much if at all. For some older jazz & pop(50's & 60's "Oldies") it is a must have for me.

I've never spent much time with the Foobar plug-in and I prefer a hardware crossfeed although the Rockbox crossfeed is very good IMO.

 

[mloh]

Quote:

Originally Posted by busyx2 /img/forum/go_quote.gif Hi, I don't recall seeing too many headphone amps that has cross feed circuit. In general, are they useful or just gimmicks?

On some records, and in particular 60's, 70's recordings like Beatles, Hollies, Led Zeppelin etc which sometimes have an instrument 100% in one channel, a crossfeed makes a big difference, and makes these records much more listenable.

Question 2 is which of the many crossfeed versions that are best. Not all DIY crossfeeds are satisfactory in my view, e.g. some have filtering which is not turned completely off in the off-position. This applies to the crossfeeds that build on the 1971 Linkwitz crossfeed like the Cmoy. They have a 1-1.5 dB fall-off in the treble (1 kHz+) when switched off. This is very undesirable in my view.

 

[Uncle Erik]

Have you tried Dr. Meier's crossfeed circuit? I put together a Cross-I a few years back and have been very pleased with it. His crossfeed sounds more natural than the others.

 

[csroc]

I think if I were going to build one I'd build the Meier Cross-1. I actually laid out a PCB design for it yesterday in Illustrator to see how I could package it and what case I could fit it in. Haven't had time to check and make sure I didn't screw something up against the diagram on Meier's size but I also haven't decided how I'd make the PCB. Had originally planned to maybe etch one myself for fun.

 

[mloh]

The simplest crossfeed you can make is the 'modern' Linkwitz crossfeed, as seen here Reference earphones (scroll halfways down). I have good experience with it.

It's a simple as it can get, just an inductor L30 in series with a resistor R30 between the two channels (neglect the rest of the circuit which is for equalization). It requires a source with some internal resistance though.

And if you open the connection between L30/R30 with a switch, it turns completely off, unlike schemes like this one which is quite popular: HeadWize - Project: An Acoustic Simulator for Headphone Amplifiers by Chu Moy.