interesting little IC (AD797) preamp

[dorkus]

Re: the audio should sound about as close to the original recording as you're reasonably

First the power supply design by numbers and now this......

Thiis my lucky day. Now I can take up bird watching since all the frontiers in audio design have been conquered.

hehe now now fred...
i was looking at that power supply thread too... i feel your pain

i think some of the older Madrigal preamps used AD797. i'm not sure about now. that said, i have never heard a Madrigal component i liked. every system i've heard with them has stunk. no life, no music. same for the newer-generation Krell stuff. sorry, not my cup of tea at all.

"cold and bipolary"... hmm, ok so that's sort of a fuzzy term but i thought most of us would sorta get the drift. i'm sure everyone's heard cold bipolar sound before. like those older-generation bipolar opamps, or bipolar power amplifiers that sound sterile and lifeless. ok it's bad of me to associate a particular device technology with a particular sound (it's only 1 of 10^12 elements in a circuit) but again, i'm pretty sure most of you have heard what i'm referring to.

i agree that tubes are highly distorted (that's why i don't like 'em) but the musical signature of a circuit goes beyond measurements like THD. this preamp has a way of presenting the music that is somewhat reminiscent of tubes - the "essense" of it if you will. you'd really have to hear it to know what i mean exactly.

(hi jocko, where's harry? )

 

[schmad]

Are you sure about use of the AD797 in ML hardware? I thought they were using Burr Brown/TI devices. Just curious ....

think some of the older Madrigal preamps used AD797. i'm not sure about now.

Yep, they sure do. Open one up and see, or just look in their more recent product catalogs where they show the guts of the preamps. The AD797 is a relatively recent product as well.

but the musical signature of a circuit goes beyond measurements like THD

Well...sorta... The "warmth" and "fullness" of sound that most people who enjoy tube amps enjoy is because of their characteristic linearity and softer roll off in certain portions of the frequency spectrum (among other things). Some people may find this and the distortion that tubes provide pleasing to the ear.

I know what you meant by "cold and bipolary" -- what concerns me is that people often expect any solid state device to have those characteristics -- IMO, this is an unfortunate misconception that needs to be done away with.

If we're just talking about amplifiers as devices which are supposed to produce an amplified copy of a source material as accurately as possible, then it all comes down to math and physics.

I'm not in any way meaning to pick on you or start a fight here either. Listening to music is subjective, and everyone has a sound they enjoy.

 

[dorkus]

Yep, they sure do. Open one up and see, or just look in their more recent product catalogs where they show the guts of the preamps. The AD797 is a relatively recent product as well.

yeah, when i said older, i meant e.g. several years old... not the classic JC designs of the 70s.

Some people may find this and the distortion that tubes provide pleasing to the ear.

i don't. i usually can't stand tube distortion - i'm a transistor man myself. however, beneath the distortion, some tube equipment can be extremely accurate in ways that solid state rarely is. i guess that's what you mean by "characteristic linearity." in particular, one area good tubes really excel at is micro-dynamics - the ability to convey dynamic shadings, inflections, the natural ebb and flow of a melody. large-scale dynamics can also be excellent with well-designed tubes, being free from the harshness and grating that often accompanies solid state (e.g. IC opamps).

I know what you meant by "cold and bipolary" -- what concerns me is that people often expect any solid state device to have those characteristics -- IMO, this is an unfortunate misconception that needs to be done away with.

not at all anymore. modern solid state gear is much kinder on the ear than it used to be. doesn't mean that there isn't still room for improvement in that area though.

If we're just talking about amplifiers as devices which are supposed to produce an amplified copy of a source material as accurately as possible, then it all comes down to math and physics.

at an absolute level - yes of course. given the realities of present-day audio engineering however, it's of limited usefulness to us. all the equations in the world won't tell you what a final circuit sounds like - only your ears will do that. we can't measure everything we hear, etc. etc. - you know the drill. and i'm coming from an engineering background too (check my profile).

I'm not in any way meaning to pick on you or start a fight here either. Listening to music is subjective, and everyone has a sound they enjoy.

absolutely, i always enjoy constructive debate.

 

[arthur]

MBL 6010D USE AD797AN IN LINE AMP SECTION AND BALANCED OUTPUT STAGE
ITS VERY GOOD

 

[schmad]

you know the drill. and i'm coming from an engineering background too (check my profile).

Wow -- how about that -- we knew each other personally at one time (it's been quite a while) That is, I should say, as long as you are MY@dorkus.org

 

[dorkus]

That is, I should say, as long as you are MY@dorkus.org

really? that's not my exact address but darn close. who are you?

 

[Ray Samuels]

Emmeline CA-2 line stage pre-amp

Hi Fred Dieckmann...
This link is for you.
Hope you will enjoy it.
Cheers.
Ray Samuels

http://www.enjoythemusic.com/magazine/equipment/0903/samuelsemmelineca2.htm

 

[mikek]

Hi dorkus...

i notice from your website, you're rather partial to classical music ...have you listened to this?

http://diyaudio.com/forums/showthread.php?postid=193093#post193093

 

[transducer]

Re: hmm...

i just did a quick comparison test between this new preamp and my current homebrew one, a simple 2 JFET Boberly buffer (a la Harry Haller) with shunt attenuator

Can you tell me more about this? Is this one of the two buffers that Borbely describes in his JFET article? If so, which buffer is it, and do you need an output DC blocking cap, or is there no DC offset? Currently I'm using a shunt attenuator as a pre, also from a Harry Haller post, but modded with an input to ground resistor to kill some hum. It's very transparent sounding as well as looking. I put it into a hockey puck display case like HH did


Thanks,
Ron

 

[sardonx]

I would imagine this thing sounds identical to my Morrison pre-amp. He was among the first to use the AD797 and I remember that he used to laugh at the fact that the audio industry was ignoring this device.

 

[Frazzled]

Re: Thanks for clarifying that...

P.S. Sorry.... its those damned elections. Like the Devo song says:
Freedom from Choice.

FRED, quoting DEVO??? I don't even know you but I know I like you!

 

[lineup]

i just received this interesting little preamp tonight from the editor of the audio magazine i write for

haven't peeked inside yet so i'm not sure of the topology, but it uses two AD797's per channel.
as for the sound, you would never guess what it is like.

this one is in same division

Emmeline HR-2 Headphone Amp $875.00

The HR-2 is a high resolution headphone amplifier. It incorporates two state of the art AD797 audio IC’s—the best ever made. It is tweaked on a very high resolution audio system and provides all the appealing magical characteristics and fullness of a well detailed headphone amp. The HR-2 is hand built with high quality electronic parts. All resistors are .1% Dale (vishay). All the caps are polypropylene and tantalum.