kevinnyc

John Hardy 990 vs. 2520: color or no color?
« on: September 29, 2006, 06:15:55 PM »
I haven't tried a John Hardy M1 preamp yet, but I have tried the API 312 preamp, so my experience with listening to both preamps is rather limited.  Nevertheless, I've been wondering:  I hear people's claims that John Hardy pre's are "uncolored", and that API preamps are "punchy".  Why would the John Hardy sound drastically different than an API when both companies use Jensen transformers and relatively similar build?  Is the cause of sound "coloration" or "uncoloration", for that matter, the simple difference between using a 990 opamp vs. the 2520?  I am aware that API only used jensen transformers on the input, not the o/p.  

My fascination with the "sound color" of these preamps came about when I called a reputable company looking to buy an API 3124 preamp to use on a classical remote recording.  The sales representative told me, "you don't want an API preamp for CLASSICAL music!  It's too colored.  You need something like a John Hardy or a Millenia pre."  

On a sidenote, I've been really focussing on tube amplification for the past few months so my theory and knowledge of solid state preamps may be lacking a bit.  From what I remember, the opamp is the heart of the amplifier, and the transformers (if there are any) are the second most important element in affecting sound quality.  If someone could shed some light on this for me that would be great.


haima

John Hardy 990 vs. 2520: color or no color?
« Reply #1 on: September 30, 2006, 03:52:12 AM »
the api 312 more coloured for various reasons (from memory):

- higher ratio input transformer (the older ones were even more low fi than the jensens)

- iron output transfomer

- lower voltage power rails

- "lower-fi" opamp (slower slew rate etc...)

the john hardy M1 uses a lower ratio input tx, no coupling caps and a very clean opamp running on higher voltage rails... amongst other stuff...

bigugly

John Hardy 990 vs. 2520: color or no color?
« Reply #2 on: September 30, 2006, 04:28:41 AM »
The majority of my recordings are classical scores for movies and TV and I couldn't live without my M1. It's got headroom for days and that is really important for capturing those loud creshendos without distortion. Plus it's extremely quiet which lets me set my levels conservatively while staying above the noise floor.

I think haima is right. Higher voltage rails and a lower ratio trans with an exceptional opamp. There are probably better transformer and opamps out there but I think the M1 is the right transformer with the right opamp. The sum is greater than the parts. But then again I'm probably talking out of my ass again. :green:
"...the land of the free*, and the home of the brave"
*some restrictions may apply, see Congress for details

kevinnyc

John Hardy 990 vs. 2520: color or no color?
« Reply #3 on: September 30, 2006, 01:04:34 PM »
thanks a lot for your replies.  About the coupling caps that you mentioned, what effect do they have on the sound?  What are the benefits (or drawbacks) of using coupling capacitors in the signal path?

haima

John Hardy 990 vs. 2520: color or no color?
« Reply #4 on: October 01, 2006, 02:36:32 AM »
coupling capacitors allow audio frequency signals to pass through while blocking any DC that may be sitting on the output. they are needed if the preamp output has a DC offset - i.e. it doesn't sit at 0v with no signal.

the M1 uses a "dc-servo" that cancels the DC that may be present on the output by stabilizing the output at 0v - some argue that this impacts on the bass sound - i believe the servo would have a inherent time constant (?) that may effect the bass i guess.

a lot of audiophiles bash capacitors (electrolytic in particular) for "smearing" audio and things like that... which is probably true to a degree. but a lot of nice gear uses coupling capacitors. the sound is probably most audible when many coupling caps are in the signal chain - like in a console...

the other way to get audio out without capacitors is to use a transformer that can handle the DC running though it without saturating - something we usually call a "gapped core"...

(BTW: some of this might be a little off... - i'm really feeling the effect of this glass of red wine! i'm on tour- too many shows, too little sleep, bumpy tour bus... but one good thing: with WIFI on the bus!)

CJ

John Hardy 990 vs. 2520: color or no color?
« Reply #5 on: October 01, 2006, 04:32:01 PM »
Goin mobile, eh?

Caps will impart a time domain shift, possibly, which could delay your signal by amount according to it's frequency, this could be looked at as "distortion" in the strictest sense of the word, since what comes out is not exactly like what goes in, from a time frame of ref, at least.

The ear does not care, it gets used to it.

I imagine it would take a fair amount of listening time to see the differences the servo makes.
If I can't fix it, I can fix it so nobody else can!
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NewYorkDave

John Hardy 990 vs. 2520: color or no color?
« Reply #6 on: October 01, 2006, 04:58:48 PM »
A servo done incorrectly can cause more harm than a coupling cap ever could. But Hardy knows what he's doing.

Bauman

John Hardy 990 vs. 2520: color or no color?
« Reply #7 on: October 01, 2006, 06:00:21 PM »
I do prefer a good cap than the servo circuit...
cheers!
Fabio
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Brad McGowan

John Hardy 990 vs. 2520: color or no color?
« Reply #8 on: October 04, 2006, 06:16:19 PM »
In my opinion transformers have just as big if not bigger effect on the sound of a preamp than the opamp.  

I believe API preamps use transformers made of steel.  The John Hardy is likely using a high nickel transformer, which will yield less coloration.  The 2520 opamp also has a slower slew rate than the 990.  I've used both preamps extensively and they definitely have very different sounds.  I would second the recommendation to use the M1 for classical over the API.  It wil preserver the dynamic range and transient response of the music in a more appropriate way.  The API can have a "hard" sound when hit with transients.  That's what makes it cool for rock.

Brad

 

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