[ev01ut10ndt]

Thanks for the explanation. I'm not an engineer at all and had no idea what the things on the datasheet meant. I would appreciate your input as to how the class A biasing sounds with the OPA627 from JTam. Did you get everything prebuilt or just the OPA itself or with the browndog adaptor?
 
Quote:

Take a look at the datasheet, It explains the difference between versions as well as has drawings of each difference.
 
Difference in how the chip is packaged, either as a solder on, through pin, or metal tin. This affects the temperature and voltages ranges it can tolerate.
 
Other difference is how individual chips are packaged for loading into industrial machines. 
 
When most people refer to the OPA627 they are either referring to SOIC versions or PDIP versions. 

 

[aspenx]

Quote:

I love this amp.
 
So today I was wondering what the gain switches did...I was initially using the 18db setting. So going from 0db to 20 db, I felt like the soundstage got slightly smaller and more blurred. Reason being is that I feel that 20db smooths out a lot of the highs but at the expense of detail and thus instrument separation. The mids at 20db sounds richer and it tames the upper mids/lower highs slightly. I scared the heck out of myself when I flipped the switch from 0 to 20db and hit play. The knob at 12 oclock for 0db is ok, but not at 20db! To get the same volume, 20db was more like 9 oclock. Nonetheless, very cool that we can just flip a switch and we get a slightly different sound signature. 
 
What are you guys using for the HD650s? I read earlier someone was using the 18db setting, hence why I was using it. I might stick to 20 since I like the rich mids and smooth highs. Who knows! 
 
And perhaps someone more technically inclined can explain...how does the switch for gain settings work? And how does it account for the slight variation in sound signatures? Just curious...
 
Once again, I love this amp. 

The gain switches let you choose which resistors you use for in the feedback loop of the opamp stage. Gain of an ideal opamp in a standard non-inverting opamp gain stage (which the M-Stage is) is determined by: 1 + (R4 / R3) where there are 2 possible resistors you can use for the R3 (which the switches manipulate how they are connected). The lowest gain setting uses ground as R3 and sets the opamp to a gain of 1 (gain = power out / power in). To convert gain to dB, you use the formula (10 lg A) where A is the gain. The highest gain setting in the amp sets uses the 2 resistors (the 2 switches) in parallel.
 
The above is of course, on the presumption that the switches work the same way on the M-Stage as it does on the Lovely Cube.
 
"Sound signature" does not change directly but raising the gain of the opamp does reduces effective bandwidth of the opamp (hence the "smooth highs"). Raising the gain is also necessary for opamps which are not unity gain stable (i.e OPA637 needs a gain of at least 5 (?) to be stable).
 
HTH

 

[BournePerfect]

My M-Stageis finally here!!! I have to pick it up at the post office in the morning lol. A couple questions though: I'll be using my PC(Zune software/ all lossless)-->uDac-1-->M-Stage. How should I have the volume controls on all 3 set? I believe I need Windows volume 100% and the uDac at 100%, then control with the M-Stage. Is this correct? Also, would it be different using the uDac headphone out feeding the Matrix versus the rca outs? Which is better and why?  I'll be installing the OP627/Browndog/class A adapter first thing more than likely. Sorry for all the questions, but I just wanna make sure I'm not adding distortion by amping something twice (3 times?) and degrading sound quality. Thanks!
 
-Daniel

 

[ninjikiran]

Windows @ 100% which is supposed to be +0db  Technically if you use WASAPI you completely evade that.  If you use a spdif on a sound card some bypass others don't,  less a worry with USB but I somehow doubt the udacs implementation of USB is all that great.  If you don't know what WASAPI is checkout foobar, easy to use and setup. 
 
The Udacs RCA output probably bypasses the volume knob on your uDac, and if it doesn't see if you can toggle somthing to make it so.  You want the udac to be a simple dac.
 
The RCA outputs are best because they are not amplified to keep this simple.  If you have amp you use the RCA outputs on a dac, not the headphone output which is always amplified and will more than likely add distortion and if no distortion will give you the same output you had before passing through another amp for further possible coloration.  Lets just say its not pretty.

 
Quote:

My M-Stageis finally here!!! I have to pick it up at the post office in the morning lol. A couple questions though: I'll be using my PC(Zune software/ all lossless)-->uDac-1-->M-Stage. How should I have the volume controls on all 3 set? I believe I need Windows volume 100% and the uDac at 100%, then control with the M-Stage. Is this correct? Also, would it be different using the uDac headphone out feeding the Matrix versus the rca outs? Which is better and why?  I'll be installing the OP627/Browndog/class A adapter first thing more than likely. Sorry for all the questions, but I just wanna make sure I'm not adding distortion by amping something twice (3 times?) and degrading sound quality. Thanks!
 
-Daniel

 

[BournePerfect]

Thanks ninji! Say I HAD to use the headphone out--would it be best to keep THAT volume control as low as possible, then use more on the other amp? Or am I losing a lot of the signal this way?
 
-Daniel

 

[gsilver]

Has anyone used a DT880 32ohm with the M-Stage?
 
I had a DT880 briefly and returned it, and one thing that was very noticeable was a buzzing sound (mild distortion) in a lot of instruments (I only tried acoustic music in my brief test, and most of the recordings were well done). I left the gain at +10db (1 on, 2 off) while I had it. My other headphones don't seem to do this.
 
Since I haven't seen people report the same problem, did I just have the gain set too high?

 

[Frank I]

Quote:

Has anyone used a DT880 32ohm with the M-Stage?
 
I had a DT880 briefly and returned it, and one thing that was very noticeable was a buzzing sound (mild distortion) in a lot of instruments (I only tried acoustic music in my brief test, and most of the recordings were well done). I left the gain at +10db (1 on, 2 off) while I had it. My other headphones don't seem to do this.
 
Since I haven't seen people report the same problem, did I just have the gain set too high?

sounds like a defective can. My T1 played well as well as the lower impedance D7000 at 10DB when I had the Matrix

 

[purrin]

Quote:

sounds like a defective can. My T1 played well as well as the lower impedance D7000 at 10DB when I had the Matrix

yup, sounds like a bad driver(s). that's how a bad driver sounded on my DT770 before it died.
 

 

[BournePerfect]

Before I blow something up, can someone show me a pic of how the browndog/op627/class a combo is supposed to go in (which direction)? Also I took the OP2134 out, am I supposed to take out the stand that it sits in as well? I think it might be soldered in.
 
-Daniel

 

[daisangen]

No, you plug the browndog w/ the OPA into the opamp socket which is indeed soldered. Remember correct positioning, the half-moon marks on the browndog and the socket must match.
 
Quote:

Before I blow something up, can someone show me a pic of how the browndog/op627/class a combo is supposed to go in (which direction)? Also I took the OP2134 out, am I supposed to take out the stand that it sits in as well? I think it might be soldered in.
 
-Daniel

 

[BournePerfect]

Thank you I just noticed the marking when you said that! I'll post my impressions afters 4-5 days of burn-in. I'm stoked!!!
 
-Daniel
 
ps: On a side not, Hlly sent me the black face plate (I ordered silver).
      I'm gonna email him and see if they'll send me the silver one or what they can do.
      David Gao...you there??? lemme know!

 

[sluker]

where would one purchase the browndog. Better yet is there a detailed explanation of how to retrofit this adapter and what opamps it works with.
This would be extremely useful for all the newbs (like me).

 

[BournePerfect]

I got the browndog op627 combo unit from coolfungadget.com for $20 shipped, and it arrived in like 6 days! Great job JTam!!!

 

[BournePerfect]

UPDATE:
 
     Holy cow this amp already impressed me. It's still literally cold (it slept at the post office last night) and has like 10 minutes on it lol. I installed browndog/op627 first thing. I just barely started listening to this song lately called Just a Dream by Nelly thru my uDac-1. It sounded good, but his vocals were seriously drowned out by the music to the point that I had to look up the lyrics to see the words. Everything just seemed to smear together, even though most of my music thru the uDac seemed clear for the most part. Now with the uDac feeding the M-Stage, all these vocals ARE CRYSTAL CLEAR AS DAY, and right up front. Holy crap that blew my mind! And this is with my .02 cent rca cables lol. The bass is definitely fuller as well. Well ima try and not post any more impressions til I get some more burn-in, but I was so impressed in 5 minutes with that song I just HAD to let you guys know lol!
 
-Daniel

 

[sluker]

Quote:

I got the browndog op627 combo unit from coolfungadget.com for $20 shipped, and it arrived in like 6 days! Great job JTam!!!

Thanks, I just ordered one. With this adapter, can I use pretty much any of the opamps mentioned in this thread?