The X-Meridian 7.1 Thread - Page 5

Sounds perfect. Use your receiver for sure. My Outlaw has a pure bypass mode for the analog inputs and I can certainly hear the difference in detail from the analog inputs to the preamp as opposed to the preamp doing the processing. It's really not close. The X-Merdian w/ LM4562 and the DC coupling mod is audiophile grade. No doubt about it.

rgreenpc - You will have no problems with having bluray and hd-dvd on the same machine I am currently running the same setup. Previously I had to have two partitions and two windows installs because Cyberlink would not allow PowerDVD to play both formats. You got an HD-DVD version or a Blu-Ray version but not both. Hence the two windows installs. But there are now fixes out there that allow it to play both!!

Discs that utilize TrueHD and DTS-HD sound amazing! The only downside is that the increased audio quality really highlights how much my center channel sucks

Yep... I am thinking the DIY speaker building section of this forum is going to cost me a lot of cash in the near future lol

First thing I would suggest is don't do the DC Coupling upgrade till you upgrade your components. Not that I am saying that what you have is bad, but the upgrade is one of those audiophile things that try to push the envelope. I have been slowly trying to remove any bottleneck in my system a piece at a time. My system was to a point that my source player had room to grow to fully expose the potential of my system. The XM with the LM4562s will probably be more than enough for 80-90% of systems out there. There is undoubtedly a difference though. It didnt get harsher sounding, just more real. The imaging is spot on now, very holographic. The clarity of the voices is creepy. They are in the room with me. It certainly was good before, but even my wife noticed a difference after I did the mod. The best way to describe it is just saying everything sounds more real. I don't think the change affected the frequency response any, just the little things like harmonics after notes, the proper attack and decay of a plucked guitar string is perfect. Things like that. The difference was going from VERY good to great..

I no longer have the mixer control as I am running Vista. This might be another reason my audio quality is so good. The volume control in Vista is more accurate and doesnt dither the source material as badly as XP does. Ideally in XP you want 100% volume. Unfortunately with the XM, that is not possible without distortion. I would run the media player at 100% volume and set the volume level of the card to the desired level. This MIGHT be better than setting the MP volume lower.

Probably a good idea. At least you know there is more quality to squeeze from the card should you want to do this in the future.

AVOpus,

Hello. I purchased the XM and the LM4562s. I have neither yet, but consider myself an auido/videophile to a greater degree than 95% of people. I noticed on my card, the caps have a base underneath and the legs are not exposed. I don't think I noticed this on your photo. If so, did you remove the base or can I short the caps from the bottom of the card? By the way, I work in the electronics field so I am sure I can handle the mod. As far as the rest of the audio chain, I plan on the NHT controller and amplifier as well as T5 or T6 towers with subs. Do you think this is a setup worthy of the cap mod? Thanks to you and ROBSCIX and others because this thread has been absolutely what I needed. I think I was leaning to a Creative Audigy and I already have a brand new ZX2 still in the box. Oh well, eBay?

WilliamH

Here is a picture and Mark's explaination of this mod. He first did it without removing the caps and then later removed them. If you don't want to remove the caps, just do it this way.

Mark: "L/R ch. of X-Meridian sound card showing initial mods. Left shows direct coupling from DAC to output, while right still has DAC to op amp caps. Right ch has 0.0001 V DC offset, left 0.0104 V (differential error from DAC). Left channel configuration safe enough for me and sounds better. If you go with the right ch. config, at least the electrolytics are DC biased for less-bad sound."

Here is what Mark's final mod looked like, although he suggest that you should just leave the caps on because he damaged his board and had to fix a trace.



Mark: "Right channel read 0.024 V. DC offset, 2.4x left channel! Note damaged trace in lower right. Suggest leaving caps in place and jumper around them."

There is some risk of this mod if one of the op amps fail or you one of your connections is bad. So you should use some discretion whether it is worth it. The caps are there for a reason, mainly to protect your equipment but at the expense of of some sound quality.

You can get to the + and - terminals for the caps. You don't actually need to jumper to the legs of the caps which I am not sure if much of any is exposed.

Sort of. I am using a Pre-Amp and an amplifier instead of a receiver. Both Outlaw. I am using the Swans 6.2s for my mains, and the 4.2 series for the center and surrounds.

I think I will have to live without this caps shorting mod. The Opamp upgrade is good enough for me. The equipment (Arcam AVP700->Aragon 2002+2005 ->7.1 Klipsch Rx7) connecting to this card totaling in the $15KUS. I'm not taking that chance, but I'm very tempted.

With that gear I would be VERY temped. You will definitely experience a benifit and it's worth it IMO. Check and see if the Arcam has DC blocking caps on the inputs. If they do then you are set and need not worry. The Klipsch will reveal the additional detail. As I described earlier, its not just additional high frequency info or a harsher sound. It's an inprovement in detail across the board. The vocals are what will really jump at you. They sound like they are in the room with you. Very breathy and lifelike.

I must caution again that you CAN fry your card and anyone who does this does it at their own risk. With that said. I was a soldering novice and probably should not have attempted this, but I did, and it worked. Luck was with me I guess.

Strangely enough , my DC output measurements were nearly identical to what Mark measured. .013 for L and .023 for the R. The other channels were a bit less.. most around .013. One at .007.

My soldering job was not as neat as Mark's as well. The wires I used went partially over the caps and not around then as his did. I'm sure that less wire is better, but it was a bit too challenging for me.

AVOpus, definitely the Arcam does have some kind of DC blocking scheme, but I'm not sure whether this protection is in the path when using the processor in direct (pure) pbypass mode.

The Arcam bypass mode is a real, real bypass. I will do further investigation regarding the amps as well. AVOpus, you convince me again into doing the mod.

I'm not an expert in soldering, but I'm not a novice either. I should be able to do it with no issue. My work has 3 high end soldering station with one of them being RoHS compliant.

Sound quality is exceptional due the reason, I'm not sure whether or not it can get any better than this. I have the LM4562 opamps.

I basically, hear no difference between letting the card perform the D/A or letting the Arcam does it. Now, mind you that the Arcam AVP700 is a mighty processor when it comes to Music playback.

ROBSCIX,

I gave my card a quick once over, but the easiest way to complete the mod in my opinion is with very small jumpers from the bottom of the card. I would make a wire with a 90deg bend on both ends just long enough to go into the holes on the bottom of the card and place it in. Then I would heat it very quickly with a pencil type soldering iron and allow a very small bead of solder to run into the hole. I think this would be a very clean mod and is probably how I will mod my card. I would also pull the OPamps from the socket while moddin. I think I'll buy another card to be on the safe side What do you think about the NHT gear? Is it up to par for the mod? Thanks

WilliamH

I looked at my card pretty carefully before the mod, and I am 90% certain that the caps are not through hole type and do not have visible traces that extend to the bottom of the board. Check it again and make sure that you look for the traces for ALL the capacitors and that you are not mistakenly looking at something else on the bottom of the board. My caps didn't seem to line up with the bottom traces at all.

And yes, NHT gear should give you the necessary headroom to appreciate the mod.

A newbie question, can I drop in a LM6172 OPAMP to the card without any mod to the circuit? The OPAMP is a bipolar OPAMP and it needs a bias input current to work. Will I damage anything if I just use the OPAMPs with the card to know whether it will work or not?

if your amps were DC coupled at the input, you'd be assured you'd know about it, it would be a great marketing point!

the effect of the small DC output (< 0.100 VDC) will be a small(?) increase in the amount of "click" or "POP" in the outputs when booting or powering up.... YMMV

Here is something stolen from another forum concerning OPAMPs. It may work and this is "Mister X" evaluation of various OPAMPs:

What are your opinions of the
OPA2134
OPA2227

Yawn.
Both of those chips exhibit the classic laid back Burr Brown sonic signature (flabby, overdone mid-bass with a nice midrange and recessed treble), they are both pretty slow and neither of them are exactly hyper detailed (which is not always a bad thing).

The OPA2227 does have a little less flab in the mid bass, a little higher level of detail and it works better @ lower voltages the OPA2134 does.

OPA2107

This one is a bit of an enigma considering it comes from Burr Brown.
It has nice balance (which means it actually has some treble). it also has a very sweet midrange and it is pretty detailed.
Problem is it sucks when the power supply is under 12 volts.
(sucks as in doesn't have much bass)

The 2134's being a common amp for audio work in genral. They all have been used wil great success in DIY audio.

lol, I think you are preaching to the choir here.

Do you hve some part #'s of some OPa's that sound better then the National LM4562's

Assuming you mean for this application only:
AD823.
(punchy bass with nice balance but the treble is a little grainy. It is a true rail to rail op-amp with excellent low voltage performance but it's output current capacity is on the low side (15mA))
AD8620.
(excellent low voltage perfomance, nice level of detail, nice speed but it is a little to agressive on the top end)
AD8066
(good low voltage performance, nice balance but it a little grainy on the top end and the mid-bass is a little veiled , excellent speed and impact)
LM6172 (bipolar):
(Excellent low voltage performance, excellent level of detail, slightly recessed treble, high output current capacity and nice speed. but it is a fussy one to say the least)

However, later on Mister X says:

and can I use the LM6172 with the card without any circuit modification?

Dunno.

And then another poster added:

Don't use LM6172 unless you know what you are doing. Those are bi-polar opamps and yes, oscillation and such is a problem. If you don't know enough to know what a bipolar opamp is and what kinds of things you need to look at, don't try it. Stick with a FET type. If you want a real high quality one that's likely to work the AD8620

Will the LM6172 do any damage to my equipment if I try to use them or do I need to measure anything first before connecting my card to my receiver?

that post, IIRC, is a bit dated....