API 2500 & op amps

[chet.d]

Hey folks, Haven't found much talk on any specific experiences with the 2500 and swapping out the stock op amps to Scott Liebers Red dots or the Purple kdj3-ins kdj4-outs.

I was talking to a tech that spoke highly of the top end opening up appreciably. (w/ the purples in his case)
He mentioned that he knew of some mastering folks that have found reason to do so.

I'm in the middle of mixing a record that's summed>2500>bax>burl b2 to capture and, can't help wondering if this relatively modest investment and straight forward swap might be a good idea.
Of course tough to say w/o hearing it in the chain but again, wondering about any others that liked what they heard w these.

[jdg]

do it.
the opamps are pretty cheep.

red dots changed my 550Ms with great furious joy

[chet.d]

Originally Posted by jdg

do it.
the opamps are pretty cheep.

red dots changed my 550Ms with great furious joy

Thanks for that. Sounding tempting.

Anyone have 2500 / mix buss stories w/ these or the purples...?

[Rob Murray]

If you do it, please follow up and share your thoughts... jdg, mind elaborating a bit?

[Greg Reierson]

Scott is visiting my studio tomorrow and I've asked him to bring some of his op amps for a listen.

GR

[t_d]

would love to hear as well.

replacing op amps on the API stuff is dead simple, so i'd love to hear more about this.

[chet.d]

Originally Posted by Greg Reierson

Scott is visiting my studio tomorrow and I've asked him to bring some of his op amps for a listen.

GR

I just got an email from Scott mentioning just this.
Indeed, please do keep us posted.
Very curious.

[jdg]

Originally Posted by Rob Murray

If you do it, please follow up and share your thoughts... jdg, mind elaborating a bit?

you might not like the difference, but i do.

alot of the 'edge' is gone.
still plenty of muscle and tone (which i think have alot to do with the xformers)

[William Bowden]

I've got red dots in my 550m as well. I did have a previous unit with the 2520 but I never seemed to gel with it, it always seemed too bright and poppy for my tastes... So sold it to Matt Gray.

There was a big gap between having the different units but I now use the red dot API a lot more, more for a colour box than any eq really. It does something interesting to the tone, helps the mids and vox area and tightens the bass (ie lessens a bit of the real lows). Doesn't work on everything, but seems to work quite often I find.

I'd say try them out and do some AB testing. Luckily it's a pretty cheap experiment.

King Willy

[livingstone]

I'm glad you like it Willy

[chet.d]

Hey Greg,
When you get a chance, please share your 2500 - red dot impressions.
Thanks!

[Greg Reierson]

Very interesting!

Here's a link to download the files. The first is the original source file, the second is a pass through a stock 2500 and the third is a pass through with Scott Liebers' op amps. I'll hold my comments until others have heard the files.

https://rcpt.yousendit.com/135338950...ee59260ba5f48a


GR

[livingstone]

thanks for the test Greg
were the 2500 in feedforward or feedback mode ?

[Greg Reierson]

Feedback mode with the threshold set at +10 and makeup gain off.

[acorneau]

Does anyone know if the 5500 has a similar capability to swap op-amps?

[Huntley Miller]

I thought the 2520 was pinch'y with a forward upper mid, and the red dot was less so - but not as good in the lower mids. Both are more veiled than the source. Scott's a great guy.

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[housegezeichnet]

Originally Posted by acorneau

Does anyone know if the 5500 has a similar capability to swap op-amps?

dunno for sure, but i remember that h-peh used an api 5500 with "scott liebers mod" and i think this mod is an opamp swap

[chet.d]

Originally Posted by Huntley Miller

I thought the 2520 was pinch'y with a forward upper mid, and the red dot was less so - but not as good in the lower mids. Both are more veiled than the source. Scott's a great guy.

I liked how the top end was more open with the red dots. I did miss a bit of the 2520 upper mid bite though. I agree the 2520 ultimately sounds a bit pinchy however.
The original source file is overall less veiled not being compressed but the top end was more sibilant and not in a particularly pleasant way such as the red dots albeit, the original file is to my ears a louder file.

Thanks for taking the time Greg.
I'm liking the red dots. At least at this moment though, missing a little of the 2520 upper mid thing.

[Tim Abraham]

I bought some red dots a while back and tried them on a variety of sources in a variety of units (3124+, 5500, 2500).

The differences between the 2520's and the red dots were very, very, small in my tests. I ended up using the red dots in 2 of the 4 3124 channels, and in the 2500. Overall I found the red dots to be (very) slightly brighter than the 2520's, which is not what I was expecting (I tested by printing mixes through the various pieces of gear, including the 3124 as makeup gain for a Folcrom).

Since I already find the the 5500 to be very "zingy" sounding, I didn't like the red dots in it as much as stock. In the 2500, which can be a touch on the veiled or dark side, I found that the red dots opened up the top slightly. With the 3124, I just stuck 'em in because I knew I could sell the 2520's for more than I paid for the red dots. Move the mic an inch and you've negated any differences.

My conclusions: I wouldn't expect the red dots to change the tone of any API piece in a particularly significant way. They do make inexpensive and easily available spares to have around though.

[Jim Williams]

At this point I believe there are more API like opamp choices than there are cheap chi-com microphones. Everyone makes one now. What you won't see are standarized tests and specs on them, that remains their mystery.

Maybe DOA's will be the next big thing at Namm next year?

[Huntley Miller]

Originally Posted by Jim Williams

At this point I believe there are more API like opamp choices than there are cheap chi-com microphones. Everyone makes one now. What you won't see are standarized tests and specs on them, that remains their mystery.

Maybe DOA's will be the next big thing at Namm next year?

SG-Acoustics

[chet.d]

I continue to debate this though I'm just touching the mix buss w 2500 + dangerous bax eq.
ie; you mastering brethren take it from there.

More open top end, or the more API-ish upper mid bite that I like, but not so much digging the relative degrees of smear?
It is my only comp these days...Hmmm
Insights & wisdom welcome.

[dcollins]

Originally Posted by Huntley Miller

SG-Acoustics

A study showing that a good IC opamp is fantastic, and some discrete implementations are hilariously bad? No one is going to believe that for a minute!



DC

[tpad]

As the old saying goes: the truth Hertz. You can do things inside monolithic implementations (IC designs) that simply would not be practical with discrete implementations. The notion that the discretes are best is about 20 years out-of-date. It's actually the other way around. The only real limitation of the ICs are that their distortion can rise rather dramatically with low impedance loading. That's easily solved with an (discrete) emitter follower output stage.

[dcollins]

Originally Posted by tpad

As the old saying goes: the truth Hertz. You can do things inside monolithic implementations (IC designs) that simply would not be practical with discrete implementations. The notion that the discretes are best is about 20 years out-of-date. It's actually the other way around. The only real limitation of the ICs are that their distortion can rise rather dramatically with low impedance loading. That's easily solved with an (discrete) emitter follower output stage.

I agree.

The exception to this is the SG/Weiss discrete opamp, which really is the best part in the history of the design arts.


DC

[tpad]

Maybe I should re-state what I wrote to say, in general, the IC implementations are the better implementations. There are always exceptions to the rule. BTW, did you see last months Stereophile magazine? J.A. claims in his 20+ years of testing DACs, the Weiss DAC that he tested was the most perfect measuring DAC he's ever seen. After looking at the test results, I would have to agree.

[dcollins]

Originally Posted by tpad

Maybe I should re-state what I wrote to say, in general, the IC implementations are the better implementations. There are always exceptions to the rule. BTW, did you see last months Stereophile magazine? J.A. claims in his 20+ years of testing DACs, the Weiss DAC that he tested was the most perfect measuring DAC he's ever seen. After looking at the test results, I would have to agree.

The only thing that discrete consistently buys you is output drive ability, and unless you are feeding 600R or less, today's conventional IC is really great.

Agreed about the Weiss - really anything they make is going to be SOTA.

I evaluated the ESS 9018 chip that they use and it's a great performer. The disadvantage is that they don't allow internal headroom for full-scale signals, so if you feed it a 0dBFS squarewave, there is clipping in the overshoot. You would have to digitally attenuate something like 3 or 4dB prior to conversion to prevent this, with a related loss in S/N ratio.

I've been working on a DAC for the last three years with the idea of meeting or beating that type of performance. You can compare (roughly) figure 3 in the Stereophile review with this FFT of 1k @ -120. Most converters don't even show a signal at these levels, or it has more distortion than signal.....


DC

[mcsnare]

When I downloaded and opened them up to test I noticed 2 things: the source file was like 9 db hotter than the 2 compressed files, and the 2 compressed files were identical and nulled perfectly. ?

Dave

[tpad]

...they don't allow internal headroom for full-scale signals, so if you feed it a 0dBFS squarewave, there is clipping in the overshoot. You would have to digitally attenuate something like 3 or 4dB prior to conversion to prevent this...

That was the problem with the old NPC digital filters of yester year. As I recall, that was how the nasty artifacts of digital clipping were first really brought to light.

....I've been working on a DAC for the last three years with the idea of meeting or beating that type of performance....

So, there is going to be a DAVE DAC? Is this for your mastering setup or something you're going to try and market?

ps - in case anyone is curious, Stereophile tested the Weiss DAC202. Pretty impressive. You can spend more and get less!

[Greg Reierson]

Originally Posted by mcsnare

When I downloaded and opened them up to test I noticed 2 things: the source file was like 9 db hotter than the 2 compressed files, and the 2 compressed files were identical and nulled perfectly. ?

Dave

Strange. Did I upload the wrong files? There should have been three files, each gain matched to within 0.05dB. I'll check things out when I get back to the studio on Monday.

GR