[WillSmoke]

Ive built several basic amps (one of which was a standard cmoy) and will soon be making, or attempting to make, a meta42. I was looking at tangent's website, and noticed that an "all out meta42" can be purchased with crossfeed. My question is, when building your own meta42, how do you work crossfeed into it? Also, Tangent's site mentions that he doesnt recommend off-board capacitors. Is there any advantage to having the capacitors soldered directly to the board? I wasnt planning on making the most compact version, but with the capacitors in planning on using, im not sure if they will fit.

 

[Dreamslacker]

So... I assume you're building a META42 (using the META42 PCB). I suppose you can use the PS capacitors off board safely. As for the signal caps, you could leave them out if your sources don't have DC offset.

 

[erix]

I added crossfeed to that circuit but I didn't use tangent's board.

To do it, I used the Modified Linkwitz Crossfeed as seen on Headwize. The input goes to the crossfeed (scale the resistor values up by 10 and the cap values down when using it this way) then on to the amp.

Here is a thread showing the circuit board. The crossfeed parts are on the outside edges of the board and the amp part is in the middle. I usually post a layout of the amp but I haven't got 'round to it, sorry. I'll try to whip something up today..

ok,
erix

 

[slindeman]

If you wait a few days you will likely see a new addition to the items Tangent offers for sale, namely a board for the modified linkwitz crossfeed that erix is talking about. AFAIK he has the prototype and will order the production version soon. So add this to your shopping list and then hook everything up as erix described. If you want to try a different crossfeed there are the two versions of the Meier crossfeed which can be found in the project library at Headwize. Either of those can be hooked up after the input just like the linkwitz, although Jan recommends they be sandwiched between buffer or opamp stages.

The shorter the distance from the capacitors to the power pins of the opamps/buffers the better. Whether its better to have more capacitance farther away or less closer is hard to say, I guess you'll have to try it and decide for yourself.

 

[Wodgy]

As long as you mount the film caps (the high speed ones) directly on the board, it shouldn't matter if you mount the electrolytics off-board. I did this in my Meta. If you omit the film caps for some reason, Slindeman's comments about keeping the distance short are right on the money.

 

[tangent]

I've ordered and tested prototypes for the Modified Linkwitz crossfeed board. I'm not doing final boards through ExpressPCB as I have for all my other boards, which should make the final boards cheaper than if I'd got them through ExpressPCB, but it means more work to get boards ordered. I'm still in the process of learning how to make proper Gerber and drill files, and choosing board houses, getting quotes, etc. I hope to get this ball rolling in the next day or so, which would mean that final boards could be here in as little as 2 weeks. Plan on waiting 3 weeks, though. I'll post an ad in Mall-Fi when final boards are ready.

On the Meier crossfeed, it simply won't work right if it isn't buffered. You'd think that a simple fix for this problem would be to sandwich the crossfeed circuit in between the META42 board and a pair of EL2001s, but that doesn't work for some reason I never figured out. My vague recollection was that there was some kind of stability problem. I got frustrated fighting with this and gave up on it months ago. That's the main reason I use the Linkwitz crossfeed -- it works well with the META42 board, without fuss. The other reason I like it is that it's simpler than the Meier crossfeed -- fewer caps, and the switching setup is simpler, too. The sound agrees with my ears, so I haven't looked farther.

Apparently Jan Meier's new Porta Corda 2 uses a different crossfeed design which doesn't require buffering, which lets him remove 2 of the LM6171s from the design. Too bad he's not sharing designs any more....

 

[WillSmoke]

First, thanks for all your replys. I will definately wait until i see the update before i order my parts. Im working on the case now, do you know if the alterations will change the board dimensions? If so, i can just hold off till i get the parts to continue working.

 

[tangent]

Quote:

Im working on the case now, do you know if the alterations will change the board dimensions?

The crossfeed board will be roughly 1.5" square. The cap positions are designed to hold Panasonic ECQP or Wima MKP-10 polypropylene caps comfortably. You should be able to use slightly larger caps than these, but certainly not huge audiophile caps.

I didn't get boards ordered yet, because I'm still fiddling with it. I decided to add mounting holes to it, and now I'm in the process of modifying the META42 design to have matching mounting holes. I plan on wrapping this up over the weekend.