My conclusion after testing 4 preamps

[djanogil]

I have four different preamps;

-UA2108
-DAV BG1
-TAB V78M
-A Design Pacifica

Since I'm not too busy at the moment, I made some comparative recordings of finger picked ac. guitar and drums OH.
I did that because I realised that I didn't really know how each preamp sounds.
They all sound good, and I wanted to be able to qualify them to make more considered choices when choosing which one to use in sessions.
My conclusion is that they all have different characters and colours, but not to a point where any of them would be unsuitable for a particular source.
What I mean is I think any good preamp can do a great job at recording anything, and that it doesn't matter so much as long as it's a quality Pre.

Now I'm wondering how much a difference I would hear with preamps costing twice as much, like high end Tube pres; D.W Fearn, Mercury, Pendulum etc..
Also could you explain what do people mean when qualifying a Preamp as fast or slow, does that refer to how sharp the transients are captured?

[Ciozzi]

Originally Posted by djanogil

Now I'm wondering how much a difference I would hear with preamps costing twice as much, like high end Tube pres; D.W Fearn, Mercury, Pendulum etc..
Also could you explain what do people mean when qualifying a Preamp as fast or slow, does that refer to how sharp the transients are captured?

You wouldn't hear twice the difference, just another character which could be good or bad depending on your taste, more expensive doesn't necessarily mean better sound.

[BLUElightCory]

Originally Posted by djanogil

Also could you explain what do people mean when qualifying a Preamp as fast or slow, does that refer to how sharp the transients are captured?

Yup, pretty much!

[Enlightened Hand]

As an answer to the question of fast and slow, I would say that it means how quickly the preamp can move current. If it's fast then it can capture transient detail well and things can sound dynamic and in your face, dare I say "punchy".

[djanogil]

Originally Posted by Enlightened Hand

As an answer to the question of fast and slow, I would say that it means how quickly the preamp can move current. If it's fast then it can capture transient detail well and things can sound dynamic and in your face, dare I say "punchy".

Thanks, that was the correct way to put it into words.
Still, it takes time to learn what to listen to when talking about subtle differences like these.

[UPRYZ]

Originally Posted by djanogil

I have four different preamps;
My conclusion is that they all have different characters and colours, but not to a point where any of them would be unsuitable for a particular source.
What I mean is I think any good preamp can do a great job at recording anything, and that it doesn't matter so much as long as it's a quality Pre.

My take: The difference between 2 quality preamps - subtle
The difference between 2 microphones - say, a SM7 and a KM184 - not subtle
The difference between a treated and untreated room - nowhere near subtle.
The difference between a nice, well setup guitar and a sloppy cheap one - not subtle
When you think about it like that - it's clear where your dough should go.

Daniel Fox

[jpupo74]

Originally Posted by UPRYZ

My take: The difference between 2 quality preamps - subtle
The difference between 2 microphones - say, a SM7 and a KM184 - not subtle
The difference between a treated and untreated room - nowhere near subtle.
The difference between a nice, well setup guitar and a sloppy cheap one - not subtle
When you think about it like that - it's clear where your dough should go.

Daniel Fox

What he says.

[JPeters86]

Originally Posted by UPRYZ

My take: The difference between 2 quality preamps - subtle
The difference between 2 microphones - say, a SM7 and a KM184 - not subtle
The difference between a treated and untreated room - nowhere near subtle.
The difference between a nice, well setup guitar and a sloppy cheap one - not subtle
When you think about it like that - it's clear where your dough should go.

Daniel Fox

thumbsup

I would only start investing in different preamps if my microphone locker is full. Or maybe I'd fill another locker and THEN start investing in preamps with different "flavors". Point is, some decent preamps will get you there.

[Ethan Winer]

Originally Posted by Enlightened Hand

As an answer to the question of fast and slow, I would say that it means how quickly the preamp can move current.

Yes, but we already have a perfectly good term for this: frequency response. So there's no need for fast and slow because those are vague, versus frequency response which is very specific.

--Ethan

[Ethan Winer]

LOL, we already went over this Mike. A few times!

Slew rate has no affect unless the circuit is driven into distortion. So unless one makes a habit of over-driving their preamps, frequency response is the only spec needed to define "speed."

Mike, I'm never rude to you. Why do you feel the need to be rude to me?

--Ethan

[Ethan Winer]

Yes, it's a specific spec. But it doesn't "kick in" unless you overdrive the circuit.

Mike, please learn to have a discussion rather than just calling people wrong. If I say something wrong, then explain what's right and why. Just saying someone is wrong with no further explanation is silly and only weakens your comments.

--Ethan

[Vum]

WikiAudio says:

In electronics, the slew rate represents the maximum rate of change of a signal at any point in a circuit. Limitations in slew rate capability can give rise to non linear effects in electronic amplifiers.

Wikipedia:

Slew rate helps us to identify what is the maximum input frequency applicable to the amplifier such that the output is not distorted. Thus it becomes imperative to check the datasheet for the device's slew rate before using it for high frequency applications.
Retrieved from "Slew rate - Wikipedia, the free encyclopedia"

[DrFrankencopter]

Originally Posted by Ethan Winer

Slew rate has no affect unless the circuit is driven into distortion. So unless one makes a habit of over-driving their preamps, frequency response is the only spec needed to define "speed."

I'm not so sure about that. I think you have cause and effect reversed. Slew rate limit will influence how readily your preamp can distort on large transients.

Frequency response is a linear criteria, and doesn't account for level dependent effects like slew rate limiting (and other forms of distortion).

For the most part it's distortion characteristics that determine the 'sound' of a preamp...frequency response by itself is pretty irrelevant (i.e. 20 Hz to 20 kHz +/- 1dB is pretty easy to get in a preamp circuit). A class A singe ended Neve driving a gapped output transformer will have different distortion characteristics than a dual supply powered API pushing a non-gapped steel core transformer...and both with be rather different than a Millenia HV-3 with no transformers.

Cheers

Kris

[Ethan Winer]

In electronics, the slew rate represents the maximum rate of change of a signal at any point in a circuit. Limitations in slew rate capability can give rise to non linear effects in electronic amplifiers.

Exactly. Distortion is the result of having too much signal level in conjunction with large amounts of HF content. So while it's not only signal level, but also HF content, slew rate limiting is still irrelevant at levels that don't cause distortion.

--Ethan

[Ethan Winer]

Originally Posted by DrFrankencopter

I think you have cause and effect reversed. Slew rate limit will influence how readily your preamp can distort on large transients.

Cause, effect, whatever - either way, it's only an issue when the circuit distorts. As you said, 20 Hz to 20 KHz is easy to achieve, and it's easy to achieve at high levels too unless the design is faulty.

--Ethan

[doorknocker]

If you ever want to sell the 2108, please let me know!

[Soulbrother]

Its amazing how many gearheads actually beleive that this is actually a measure of "how fast' a preamp is and how it responds to transients, as if transients were somehow a seperate thing to the rest of the audio.

If a preamp has a frequency response of 20-20,000 then it captures your transients perfectly faithfully - transients are just short bursts of high frequency content no different to any other peice of audio.

I presume this one was pushed out so that we could pretend there is some extra reason we would need to spend money on fancy preamps,.

[lord_bunny]

The only reason i bought outboard pre's beyond my humble 1208b side-car was noise-floor, beyond obvious considerations. I needed pre amps that could let me use an R84 to mic an acoustic played softly from 3' away... or to distance mic strings etc.

There is a tonal difference between my Aphex 1100 and my Great River MP4H... and they're both around $1000 per channel but it's microscopic comapred to the microphone's response and the stuff your sticking it in front. The limitation on both these units is the lack of output control, but you can always buy a passive output.

Oh, and the 1280B is great for a little saturation/distortion when overdriven. So is the LA610.

So if you have a few that can distort pretty and a few that can deliver lots of amplification cleanly you've covered your bases. Something like the NV series by great river can do both I'm sure.

nosebleedaudio: It's fine if you disagree with someone, but being an ass about it doesn't exactly make you look like Einstien. A little unprofessional I think.

[mikethedrummer]

So, frequency response is the range of frequencies the preamp can pick up, 20Hz to 20kHz. This part I am sure of.

The slew rate is how quickly the preamp will read a signal. So for instance, a snare drum through an API would not have any distortion (or very little) but say through an Avalon (a "slower" pre) there would be some sort of distortion due to a slower slew rate that cannot keep up with the sharp transient of a snare drum. This distortion is what defines the natural colors of the pre's on certain sources.

I'm more asking than telling :x

[Ethan Winer]

Originally Posted by mikethedrummer

The slew rate is how quickly the preamp will read a signal.

No, slew rate is how fast the output voltage can change. The whole notion of "fast" and "slow" preamps (and subwoofers etc) is sorta misguided. Yes, slew rate is a factor, but it's more of an "internal" spec that end users don't need to worry about. Except maybe with power amplifiers where there really are very large output voltage changes. Bottom line, if a circuit can output 20 KHz at full signal level with minimal distortion, and your source content has no energy above 20 KHz, then its slew rate limiting is acceptable and not worth worrying about.

--Ethan

[DrFrankencopter]

Here's a National Semiconductor app note that deals with slew rate limiting:

http://www.national.com/ms/LB/LB-19.pdf

and here's a nice quote from it "Equation 5 demonstrates that the borderline between small signal response and slew rate limited response is not just a
function of the peak output signal but that by trading off either frequency or peak amplitude one can continue to have a distortion free output."

In otherwords, there is a tradeoff to be had between peak output power, distortion, and frequency response that is imposed in part by slew rate limiting.

Again, frequency response is limited to the small signal response of the circuit, where its behaviour is largely linear. It's not accurate to say that a preamp with 20 Hz- 20kHz will accurately capture ALL transients, unless that frequency response is applicable to the ALL output levels that we will encounter.

Cheers

Kris

[Brainchild]

Aside from the inexplicable nastiness (which in one minute managed to put me off JMK products for life; congrats on that), this has been an extremely fun and informative thread.

[Brainchild]

Lollygaggers on the unpredictability of that response. You go, girl.

[Brainchild]

Please.

Good luck with all your future endeavors.

[Ethan Winer]

Originally Posted by DrFrankencopter

It's not accurate to say that a preamp with 20 Hz- 20kHz will accurately capture ALL transients, unless that frequency response is applicable to the ALL output levels that we will encounter.

Agreed, which is why so many specs are incomplete and misleading! They'll give the frequency response at low levels, and the maximum output at 1 KHz, but not both!

--Ethan

[Tone Laborer]

Originally Posted by BLUElightCory

Yup, pretty much!

Best answer yet.

[bongo_x]

One of the things I like about this board is that I can figure out who I don't want to deal with. I started keeping a "don't buy" with my "buy" lists in case I forget.

bb

[djanogil]

Originally Posted by doorknocker

If you ever want to sell the 2108, please let me know!

Haha, never!!

I wish I had a couple more!..

[chrisrnps]

Originally Posted by Brainchild

Aside from the inexplicable nastiness (which in one minute managed to put me off JMK products for life; congrats on that)...

Same here.

Gentlemen, when you appear here and elsewhere as 'the face of the company', what comes out of that face's piehole makes a lasting impression on potential customers.

If you choose not to let your products "speak for themselves", every comment you make online is not only 'forever', it's taken as the voice of the company. And there are plenty of other $1000-and-up this-year's-best-two-channel-preamps-ever to choose from.

[Tom Hakala]

Originally Posted by chrisrnps

Same here.

same here.