San Jose Meet Impressions:
Jun 15, 2004 at 2:16 AM Post #31 of 42

mtkversion

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utep10,

That Massive Attack - Protection ( burned CD ) is probably mine.

I have the original at home so you can either keep it to take a listen or use it as a coaster or a frisbee of some kind.

Thanks again for hosting and letting us all use your house for the meet ...
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Jun 15, 2004 at 2:36 AM Post #32 of 42

Lil_JV

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Thanks for the info amb! I look forward to this amp and I will definitely be building it. I have actually assembled one of the v1.2 boards but never got around to wiring it up. Are you thinking about using the Hitachi MOSFET's? I guess I will have to build this amp if it is actually better than the HR-2. I have some parts laying around that should be good. (6)3300uf Nichicon FG's and (4)330uf Nichicon KZ's.

JV.
 
Jun 15, 2004 at 3:53 AM Post #33 of 42

Gord SW Ont

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Quote:

How did this amp compare to the HR-2?


I think my modified SDS sounded cleaner, more neutral, with better detail and air than the HR-2. We had a couple of special A-B switchboxes at the meet that allowed us to instantaneously switch between amps (using the same source and headphones), which made comparison very easy. To make the comparison more "scientific", one of the switchboxes is "semi-blind" in that it is not obvious which switch position corresponds with which amp unless you disconnect one of them. Also, I used a test tone CD and a voltmeter to match the levels precisely.


================================================== ======

Do you know what op amps were in the HR-2? I've found you can get various effects with different op amps on the HR-2 (please note I'm not alluding to how it compares to the SDS
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Personally have tried AD797, AD8610, AD8065 & OPA627BP. I think I like the latter two the best (currently have had the 627's installed for some time) but the AD8610 might be considered the cleaner/more detailed of the lot ... not necessarily the best for my Sony 3000 headphones.
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Sounds like a great meet ... I'd really love to hear all that fantastic equipment!
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Jun 15, 2004 at 5:16 AM Post #35 of 42

amb

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The HR-2 is supposed to have AD797 in it. I assume that the HR-2 at the meet was unmodified, but I don't know. My modded SDS Labs amp was running a AD8620AR at the meet (even though I briefly rolled a AD8066AR in there for comparison, but switched back to the 8620).

For the new amp that Morsel and I are designing, we have not firmed up the plan on which output MOSFETs to support, but *if* we must do only one version of the PCB, it's probably going to be the IRFs. It's unfortunate that the Hitachi/Renesas are not pin-compatible with the IRFs. While the Hitachi/Renesas 2SK213/2SJ76 series have nice low gate capacitance and low gate turn-on threshold, they also have low transconductance and limited current capability (only 0.5A, contrast that to 17A/19A for the IRFZ24N/IRF9Z34N). I would like to have an output stage that has real chutzpah (to be able to *drive* difficult lo-Z loads with ease even at high volumes), and using those Hitachis would mean needing to parallel multiple pairs, negating some of the low capacitance advantage and adding complexity, PCB and heat sink real-estate and cost.

The IRFs are not pigs as far as gate capacitance go, considering their high current capability (e.g., lower than the Hitachi 2SK1056/2SJ160, which are rated at 7A). I achieved very good high frequency performance with the IRFs on my modified SDS amp. Frequency response is -3dB at well over 1MHz with all the good, fast opamps (see the measured specs and square wave performance on my web page for it). Even the 200KHz square wave response is beautifully steep and clean with the right opamps.

I have tested the circuit on a breadboard with the Hitachi 2SK213/2SJ76 MOSFETs, and they do extend the high frequency even further, but we're talking about something so far out of the audio band it's really academic. Sonically, I don't think I could distinguish any difference between the Hitachis and the IRFs with my HD600s.

So, perhaps the gate capacitance issue is a moot point. What is important is that the IRFs are readily available from Digikey and Newark, and are less expensive than the Hitachis. Not to mention that only one pair per channel of the IRFs is needed.

Anyway, I think this is drifting off topic for this forum. Morsel and I will post on the DIY forum when we have something more concrete to discuss.

-Ti
 
Jun 15, 2004 at 2:24 PM Post #36 of 42

gpalmer

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Quote:

Originally Posted by amb
The HR-2 is supposed to have AD797 in it. I assume that the HR-2 at the meet was unmodified, but I don't know. My modded SDS Labs amp was running a AD8620AR at the meet (even though I briefly rolled a AD8066AR in there for comparison, but switched back to the 8620).


The HR-2 was an unmodified version with AD797s in it. They do make the amp dark sounding instead of being neutral so this might have contributed to Ti's observations. In particular I think the observations of it being "more neutral, with better detail and air" might be due to the AD797 opamps. It might be interesting to try comparing the two amps with matching op amps so we're not comparing op amps so much as amp designs. I know NeilPeart was very impresssed with the prototype, and I listened quickly, but I came to the meet with socializing on my mind more than critical listening so I didn't bother to bring any music I was familiar with and really couldn't compare the two.
 
Jun 16, 2004 at 2:19 AM Post #37 of 42

shafu

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Quote:

Originally Posted by utep10

The Accuphase DP-85/Singlepower MPX3 w/Sylvanias/Sennheiser HD650 w/Zu Mobius Cable was the most enjoyable setup I heard at the meet. EWF never sounded so good. Maybe I can sell the house to get that Accuphase. Shoot, the Accuphase remote was heavier then my....... never mind.



The Accuphase was beautiful to look at and listen to. Miles Davis (SACD) never sounded to damn good - if you really wanted proof on the sound quality of SACD, this is a pretty set up to listen to.

I'm sold - the source does matter! My RKV with the Rotel DAC was pretty damn nice too. My equipment really sang with some serious hardware upstream.

I had a great time and enjoyed meeting everyone. There was a nice mix of equipment although I have to admit I didn't get to spend as much time as I wanted to with all the set ups. The one thing that surprised me was the opportunity to discover some new music - I don't remember what I was listening to, but hearing other people's music with their set up was nice. It's probably a great way to discover new music.

The PS1 is as good as advertised. With Gplamer's balance set up - wow. The only thing that came close to my initial reaction to listening to that for the first time was the RKV/K1000 combo. And this was much much better.

The PS1 is a lot darker on the RKV and the MPX3 - I was pretty surprised by that. Not bad, and not boomy bass, but the overall tone was much darker than the HD650/Zu cables.

Thanks again Bruce - you were a great host.
 
Jun 17, 2004 at 5:25 PM Post #38 of 42

gundam91

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Bruce, thanks again for hosting. That was me sitting on the floor salivating over Shafu's Audio Valve RKV MkII. The transport was the Sonic Frontier SFT1. I'm fairly new to this headphone business, and wanted to actually hear some amps before purchasing one. I was pretty most impressed by Ti's prototype and the RKV at the meet. Shafu was nice enough to hook up his RKV to my gear. So most of the time, I was just sitting there listening to this amp.
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I was not too impressed with the Emmeline and the PPA. Both of them did not pass my torture test as the midbass sounded boomy on this female vocal accompanied by solo piano Chinese CD that I played. PPA was on my original short list. Now I've removed it and added the Audio Valve RKV MkII to that list with Rudistor RP-5. But I think for now, I will just be content when the HP-100A and Consonance Cyber 20 get here.
 
Jun 17, 2004 at 7:15 PM Post #40 of 42

ayt999

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Quote:

Originally Posted by utep10
Thanks for the "stuff" from Japan. That was some good crap
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.



leave me feedback if you like. you can practice finding my feedback thread.
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btw, my grandma ordered it and got it delivered straight from the source to her place so it should be very fresh.
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May 8, 2007 at 6:37 AM Post #42 of 42

neilvg

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Me too
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I originally joined headfi in 2003 but totally (and still to this date) forgot my original log in. One year later in '04 I signup as neilvg, and remember my login this time. I remember my first meet, it was 2004, in Oakland at the Mother's Cookie's Complex
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===

Btw, Welcome to headfi... umm, oh yes, sorry about your wallet! So umm, now that I've greeted you, allow me to be the first to tell you that this meet happened 3 years ago!

Neik
 

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