Practical Devices XM5 - Page 9

AD8397 Upgrade

Just an update, rolled in the AD8397 opamp, kept the BUF634P buffer, the sound felt like a total upgrade! The harsh treble associated with the OPA134 and HD600 was totally gone. The AD8397 handled treble sibilant much much better than the OPA134. Bass is a touch less, just a tiny touch, but seems more controlled. But lower-mids seem to be more obvious, which makes the sound warmer. Totally enjoyable, totally awesome!

I plan to try the AD8397 dual to singles module, OPA627 and AD743 later this week. I don't have any AD797 anymore, but I do have some NE5534 left over from a Xin SMIII I could try as well. Just need find the time.

I received a stock cable for my HD650 today and have been testing my XM5 with some bass heavy electronic music with iPod Classic as source. I'm currently using the treble boost with high gain. Very good sound overall but when pushed hard(unsafe volume), I am able to get the amp to clip before the volume is painful. Of course I did this only as a test but it does reveal the limitation of the XM5 with HD650.My volume at this point was around 1 o'clock.

Switching to my favorite female jazz/pop artists is a joy. Using the treble boost is just right for my taste and it gets me closer to how I listen to my 650 using the Aphex 204.

I'm hearing a very nice soundstage with a crisp dynamic snap with brass & percussion...now excuse me while I veg out for a few hours...

Interesting !! I thought that the 8397 had greater current output then the BUF634's.

How's the battery life with those chips??

I've been keeping my eye on this thread and this page has me a bit confused. According to the PD website, they claim you do not need the separate buffers (BUF634) if you use opamp AD8397 because this particular opamp has a built-in buffer. If you're using both and making the claim that it's a significant upgrade in SQ, it would appear that buffering is just as relevant - or, even more important - as picking the "right" opamp. Is this the case? Don't some of the Xin amps use a ton of buffering?

I have the BUF634's installed in my XM5 but have not swapped out the stock (OPA134) opamps at all. It would be very cool if this thread could continue with people posting their impressions of the amp's sound sig with different opamps installed. Maybe somebody with several compatible opamps at their disposal could post a chart detailing each opamp's strengths & weaknesses? It would be invaluable to folks like me who would like to upgrade a bit but have limited finances (the AD8397 DoubleCat opamps on sale at the PD website for $40 a pair are financially out of reach right now to me...) I'd really like to pick up a pair of "better" opamps and check out the difference in SQ.

To stick with the original intention of this thread - I, too, love my PD XM5. I normally listen to it with the +10dB and x-feed functions "On" through a pair of DT770's (with a 75ohm resistor mod) fed by a custom LOD from my iPod Touch (with "Bass Reducer" enabled - those damn DT770's!!!). IMO, it's a great little transportable rig.

Thanks, folks.

I see those @ $22.

I wouldn't mind trying different op amps but I don't have the time or money to spend on what I consider to be minor(not worth it) improvements/changes.

If there was some major revelation discovered where the amp sound sig was drastically changed to favor the HD650 I would try it...if the cost was not too high...although I don't feel like it needs changing.

Otherwise, my XM5 sounds very good with HD650 and there's really nothing lacking. The features make this amp work great with every can that I have.

I tried some OPA227s, but my ears couldn't tell much of a difference. Don't have access to any other opamps.

But you need one for each channel, which equals ~ $40 total.

If a reasonably-priced set of opamps could give even a slight improvement in SQ, I think it would be worth checking out. Even Tangent, on his website, notes the (sometimes dramatic) difference an opamp can make in the CMoy design. Aren't amps like the XM5 essentially a glorified version of the CMoy?

I like mine, as well!

From PD website:



AD8397 and busbars installed (AD8397 is a dual-channel chip with integrated 300mA very strong buffering).

There is a subtle difference between AD8397 with BUF634 and no buffers. I'm currently doing a direct A-B comparison. With the buffers, the bass is more pronounced, and the sound is warmer. Without the buffers, the bass leaner, but has the same impact and extension. The sound is also a bit cleaner, but less warm. Your call!

Thanks Dane & Penguindude. It doesn't look as though spending the extra money will pay off in terms of a substantial upgrade in SQ. Plus, because I use the XM5 with a pair of bass-heavy DT770's, having a bit more bass from the 8397's in the sound sig of this rig is not something I'm looking for at all .

hello guys! (:
new here and a noob to all these audio stuff.
I'm interested in getting a XM5 and was reading about it and I'm wondering if anyone could explain what buffering is?

and just wondering, you guys are using the interconnect that they provide? what's the sound of their interconnect compared to the other ones available? is it more bass centric or increases clarity?

Wait, how does that work?

does that mean I should get the AD8397 for like 22 bucks AND the BUF634P for 45 bucks as well?

No need for the BUF634P if ure getting the AD8397.

Anymore reviews of this amp coming out? A few members said they were going to post reviews a few weeks ago but I have not seen them.