Alternatives to ZapFilter mk2? [balanced output stage, kit or assembled, maybe tube?]

[philodox]

Hey all,

Since the ZapFilter mk2 seems to be impossible to get right now, I was wondering if there are any alternatives. I would like to install a nice balanced output stage into my Eastsound CD-E5 Signature. [Crystal CS4390 DAC chip]

Currently it uses a NE5534 for the phase inversion to accomplish the balanced outputs and I would like to improve apon this with the upcoming arrival of my balanced headphone amp.

I would prefer a preassembled board like the ZapFilter, but if there are kits available I am sure I can get someone to assist me with the assembly.

A balanced tube based output stage would be interesting as well.

Thanks in advance,

Jason

 

[Pars]

Well, not much of a drop-in or pre-built, but check out:

http://www.tentlabs.com/Products/Com...DAC/index.html

and

http://members.chello.nl/~m.heijlige...tml/dactop.htm

You would probably be better off just getting rid of the Eastsound and starting over if you were to go down this path...

 

[philodox]

Quote:

Originally Posted by Pars You would probably be better off just getting rid of the Eastsound and starting over if you were to go down this path...

Why? It has a good DAC, decent transport, good PSU, good clock...

Thanks for the links, I will check them out.

 

[DigiPete]

Doesn't partsconexxion have any Zapfilters?

If not, try Matthew at SACDmods, he might be willing to sell you one.

The Zapfiltered E5 I modded sounded awesome!!

 

[philodox]

Nah, Parts Connexion is out.

It's funny, I called the other day. Asked if I could check stock on something. The lady laughed and said, "No, we do not have any ZapFilters". It seems there are a lot of people calling.

I will check with Matthew, thanks for the tip.

Pars - That DAC looks cool, but a little more advanced than what I am looking for. I'd really like to just find a simple DIY balanced output stage.

 

[cetoole]

You could get a pair of nice audio transformers; check the offerings from Cinemag, Jensen, Lundahl, Sowter, and there are plenty of others. You could also build your own SE - Balanced stage, or, seeing as the CS4390 has differential voltage outputs, you could make it into a true balanced source relatively easily. I dont have a schematic for the E5, but my guess is that it uses opamps to sum the differential outputs into a single ended output, nulling DC offset. If you were to remove parts from that point, and use the pads for the opamp to feed into your own buffer/filter stage, and then add a pair of XLRs to the back panel, it would turn your E5 into a fully differential output source. It looks like the Zapfilter does the same thing, and just acts as a buffer/filter stage for the DAC. There are plenty of good schematics available for these stages, and its much simpler than if you had to do I/V as well. If I was in your position, I would either do this (DIY differential output stage mod) or go with Pars suggestion, and replace it with a different source.

Wait, What? The E5 provides differential outputs, but does so via an opamp phase inversion stage? Why? Its DAC already provides for differential output, without an analog phase inversion. Oh well, since it already has a pair of XLR outputs, it would make doing the mod I suggested much easier.

 

[philodox]

Thanks for the input cetoole.

I've actually been thinking that I may try simply wiring the outputs of the DAC directly to the balanced outputs using four polypropylene caps. Way cheaper than getting some good iron, and I have yet to hear a transformer output source that really impressed me. I'm a little worried about the tonality that the caps will add to my source, but the way I look at it transistors, mosfets or tubes would all add their own tonality as well... so it is much the same thing.

I talked to Peter, and my amp will have a 25k input impedance, so 2.2uF should be high enough to prevent any bass rolloff. It should have enough gain that the reduced voltage will not be a problem.

He also mentioned that if I go too big in the capacitor value it can cause issues as well. Anyone know why this would be? I've always been of the mind that bigger is better where caps are concerned...

 

[eVITAERC]

I spoke to the guys at LC Audio, and they said that there's been some production difficulties with the ZAPfilter Mk II. However, they said they expect to have some in stock in a couple of weeks. Obligatory grain-of-salt, of course.

 

[DigiPete]

Matthew at SACDmods likes Auricaps. He says he has tried just about every cap out there.

PS. I am upgrading the clock in my 3910 to this one:

http://www.newclassd.com/index.php?page=20

Tomorrow I open it up and put in hexfreds.

 

[Iron_Dreamer]

Quote:

Originally Posted by philodox He also mentioned that if I go too big in the capacitor value it can cause issues as well. Anyone know why this would be? I've always been of the mind that bigger is better where caps are concerned...

Bigger is not better where caps are concerned. In this case, the capacitors in question present the DAC chip with a capacitive load, and a very large one, which is generally a bad thing to do with a dedicated output stage, let alone the weak direct output of a DAC chip. Having done this myself to a soundcard, I can say that it's a mixed bag sonically. I'm sure a more experienced technical member could explain in more detail the problems created by a capacitive load.

 

[philodox]

DigiPete - That is the clock I am looking at as well, though that will be further down the line.

Iron Dreamer - Thanks, that sheds some light on what he was trying to tell me. I think that at the cost of four 2.2uF caps it is definately worth a try though.