Really good question Mark ….. love it.

Well the two crucial specs I feel are dynamic range and frequency response.
Once you clear those it can be really creative.

1/DYNAMIC RANGE

There’s a certain point I reached , I can’t remember when excactly , when I thought I had a useable range in the design.
A lot of it involved maintaining space in the electronics …that’s why all my units are 2U rack spacing.
You need space in high impedance (valve) circuitry , especially between the input and mains transformers (obviously) if you want to run a lot of gain in the circuit and minimise noise floor and so to maximise DYNAMIC RANGE.

Now I’m getting sidetracked here but what also constitutes good DR also is the notion of the musical clipping.
Stick a sine wave through the unit and see the wave bend when you push it.
Does it have a flat edge?….a flat edge is not musical.
It must be smoothe,,,like a rose.

2/FREQUENCY RESPONSE

You can’t get away with much.

No manufacturer likes to say that their pre isn’t 20-20 flat ,
Or at least within 1db.
…and now there’s a stupid race on bandwidth.
Tell me about it.

Go check out the classic EMI Telefunken specs from Abbey Road.
I think 30hz-15khz before severe roll off.
Don’t quote me but it’s certainly not a huge window as far as top end response is concerned.Certainly not the bandwidth of say a Mackie. :eek:

Can there be a build up of useless sound energy caught above 20khz that isn’t doing my music any good?
I think so.

Mixing will take longer. :td:

....getting back to the point...

I use maths to get me into the vicinity.
You know E=i/r and all that.Then apply a logarithmic feel when you deal with component values.

If you're chasing perfect spec all the time you end up with what's already out there.Pure Shite.
It ends up being the Microphone , it's so perfect.

There are parallels I draw all the time:

Exciting food takes risks.
Exciting music takes risks.
Exciting audio takes risks.

Spacetravel.
Miles Davis' Bitches Brew.
Gin and Tonic ..and Vodka.

So yes , the Ear has the final say.
But you’d be surprised how closely it agrees with the oscilloscope anyway.As soon as you get that flat ridge it sticks out like a mile….
To the ear and the eye.

Sebatron,
...Are you suggesting gin + vodka + tonic = a good drink? Doc

...maybe for the first two.....

Then it's 'scotch and coke' ,followed by a fine port.

... any port in a storm ... and all that.

:D

Hey Kev,
Matey!
Good to see you hear mate!

I always thought you had good hereing. :D

Originally posted by Sebatron:

I use maths to get me into the vicinity....
Then apply a logarithmic feel when you deal with component values.....

If you're chasing perfect spec all the time you end up with what's already out there.Pure Shite.

As soon as you get that flat ridge it sticks out like a mile….
To the ear and the eye.

...so where do you stand on PSpice and emulation?

Or do you trust the old (and much under-rated) "Breadboard'n hack it" approach :D

Mark

--------------------------
"Oscillators don't, amplifiers do....."
Anon.

Hi Seb, BTW... did you mean V=R x i ?
Maybe I am missing something..
Nice weekend my friend!

I am eager to pick my vmp200e. Carlos is going to contact ya soon, mom with problems at Sydney. :(

Hey Alecio ,
Yes , v= e * I , that works as well.

Yes I got the message about Carlos’ Mum.I hope she’s alright.
Did you say it was the femur?…broken?

Man , that’s really painful. :(

Don’t worry , I’ll keep ya baby (vmp-2000e VU ) warm as eggs.
We’ll sort it out.Just don’t break no bones.OK?
BTW , Alecio , Can you stick that photo of the world’s biggest guitar up?
I think everybody here should see it.

Mark , yes I virtually live by the bench.
I don’t believe in that Spice stuff man,I don’t believe in Heroes, I don’t believe in Yoga , I don’t believe in Elvis , I don’t believe in Zimmerman , I just believe in Me
The benchwork and me,
AND THAT’S REALITY. :D

Hi Alecio,
By the way I am finally getting to use my sebatron pre. It is a sweet unti!

and BTW ohms law is E=IR
E = Electromotive Force better known to us common folks as voltage

You know the rest.

You see us EE's need to protect our jobs so we like to make up stuff that makes no sense to anyone else (like voltage representaed by E). If you think thats bad just be grateful you live ina country that uses mks so you don't have to learn american engineering units, talk about a lofd of c$%p.

Steve

Sebatron I think its time to move ahead with our plan

I am very happy to see some of these units getting into the hands of others. Perhaps they will attest to what I said in my review of the vmp 4000.. this is one of the "best buy" pre amps on the market.. closest thing to "free lunch" there is..

I have received so much flack for saying that I loved the VMP and that it blew my Amek Neves out of the water.. I just hope the people who slammed me so hard will have the intestinal fortitude to make an apology to me, once the facts are known. I really don't expect them to however.. They will still be entrenched in their "Rack Crap" mentalities.

I think the word must be getting out that Sebatron gear is the real deal. I don't see half as much Noise on the bulletin boards these days. Also, I never read anyone actually put down Sebatron units for sounding bad- peeps was freaking cuz of what were (apparently, but inconclusively) fake bbs members posting gushing words on Seb. I read some the threads and the posts DID seem to be implausible, but it seemed so obviously fake that I can't think anyone in the Sebatron Company would actually think they could get away with it. I think anyone with any sense would realize that the ensuing firestorm would most likely hurt Seb more than help (I don't know, tough to gauge- on one hand I think a lot of potential buyers may have taken a wait-and-see attitude due to potential underhandedness, versus the old PT Barnum saw that any publicity is good publicity as long as they spell the name right). My best guess is that someone who is a little too overzealous a fan got a little out of control.
I hope that the whole thing has calmed down. I also think Kurt just happened to review the Seb at the wrong time- people were looking for a conspiracy anywhere they could find one. I can't find any fault with Kurt's review- very pro, even posted sound clips comparing various pres. On to better topics? David

intestinal fortitude

What do ya think.....

Band Name?
Song Name?
Album name?
Unit Name.....maybe a dedicated Bass D.I?

....can i borrow that one Kurt?....... :D