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Mic preamp audio examples

I'm willing to post audio samples of various Input Tranformers and Op Amps on an ADK AP-1 mic preamp, if anyone is interested.

But I don't want to go through the time and effort of doing this if it's not of interest.

;)

d.

Comments

DonnyThompson Fri, 02/27/2015 - 02:30

I'm happy to do the recording, as it helps me to get to know the color/characteristics of each of the components, and combinations of the various trans and op amps - I just don't want to take the time to post them here if no one is interested. ;)

But for you Bos... ? Anything. ;) LOL It's the very least I can do for you - after all the times you've helped me through the technical-electronics jungle... :)

d.

DonnyThompson Fri, 02/27/2015 - 02:33

@Boswell @audiokid @Kurt Foster @pcrecord @kmetal @Smashh @Davedog @dvdhawk

If I can get just 4 people to respond in the affirmative, then that's enough people interested for me to post samples here.

If not? I'll send them to you (Bos) privately. ;)

MrEase Fri, 02/27/2015 - 04:13

Hi Donny,

I agree that it should be an interesting experiment but will need to be done in a very controlled way to get the most from the effort. Please make sure you keep as much as possible "equal" between takes!

I find that it is always intriguing (as I'm sure Boswell does) to observe the different outcomes. What I find though is that many will condemn or praise some particular IC or other without taking in to account the circuit surrounding it. Op-amps have such varied characteristics that every circuit should optimised, so dropping in an alternative does not necessarily reveal the Op-amp but rather the circuit it's in. Nevertheless an interesting task but for me, as a designer, I'd also like to see the circuit schematic's that yield the results.

Now transformers are largely a different matter as their construction can vary wildly. I've designed many different types of transformer (mainly for R.F. frequencies rather than audio) but it is crucial to get a good design for either type. Of course the circuit will also affect the outcome but perhaps to a lesser extent due to the compromises made in transformer design. Perhaps some photo's of the transformers would also help so the type of construction can be seen.

I look forward to hearing your results.

P.S. I was so tempted to vote "Go away Donny!" :

DonnyThompson Fri, 02/27/2015 - 06:17

I've done as Marco suggested, and recorded several different takes, using various transformer/op amp combinations, with an SM57. It's probably smarter to do it this way, as the 57 is much more common in home studios, and I realize that not everyone has an AKG 414EB laying around.

MrEase - the transformers included are: a Sowter 9820, a Lundahl 1538, a Jensen J-110-C, and a stock ADK.
The Op Amps are: a John Hardy 990C, an ADK Vintage, a Cinemag, and a Seventh Circle Audio SC25.

I can supply the info as to which sample uses what combination, but I don't have access to any schematics for these. I've been told that companies like API are pretty guarded about letting that data out to the public, although I do know that there are a lot of API 2520 "clone"s on the market. I believe the John Hardy is one of these. Whether or not it sounds exactly like an API is, I suppose, dependent on how well you know the API, along with an individual's perception of the sound, and, in what context it's being used - the mic, the vocalist, the environment, the style, etc. - all of which seems to play more of a bigger part than anything else, when determining whether someone likes it - or not.

I wouldn't be the least bit surprised to learn that many of these designers keep their technical info close to them. From what I've read, it's almost like making fine wine, and each developer has their own kind of "vibe" when it comes to designing and building these components, and it's that "character", that fingerprint, that gives them their reputations, so I would totally understand why someone like yourself would prefer that their designs and schematics not end up all over internet audio sites for everyone in the world to download. ;)

I didn't buy these trannies or op amps - for that matter, I didn't buy the preamp, either - a friend of mine is lending me this ADK AP-1 pre while his house (and studio) are being remodeled, and these are the various models of transformers and op amps that he sent with the pre.

He thought I'd get some use out of it - he knows I've been looking recently at purchasing one high end mic pre (budget $800-$1000), and I will admit that I am intrigued by the "pop and swap" design on this preamp, which allows the user to swap out any tranny or Op amp without having to solder, or, even having to use any tools, either. You simply line up the leads to the socket, and pop them in. They come out just as easily.

One thing I've noticed - besides the obvious (and sometimes not so obvious) differences between the Trans/Op Amp combinations, is that this pre is whisper quiet. I've had the gain up to the max on this thing, and it's dead silent.
The guys who built this pre obviously put some time and care into it.

I'll post some samples later today, and probably through out the weekend, as my time allows.

:)

d.

dvdhawk Fri, 02/27/2015 - 20:23

I would echo Mr. Ease's sentiments about methodology. If it is done with a reasonably scientific approach (no more than one variable at a time, if possible), I would be VERY interested in hearing the results.

Measure and document everything you can, and maybe don't tell us which combination is which - letting the listener form a impression of the sound without bias. Then at a later date reveal which clip used which combination.

DonnyThompson Sat, 02/28/2015 - 03:55

well, here's how I did it:

I sang the same 8 bar, single voiced verse of a song that I wrote. This takes out the bias of any familiarity of a song that you've already heard.
I sang it into an SM57, on a stand, with the mic position never moving.
I did my best to remain the same distance from the mic, on axis, every take.
No gain changes were made on the pre at all. The gain control remained in the exact same position.
There has been no EQ added at all, either on the way into the DAW or afterwards,
The same goes for gain reduction.
The only variable was the combination of transformers and op amps in the pre.
I changed only one component on each take - I never changed both the transformer and the op amp at the same time.

Remember guys, I did this for my own benefit first.
I wanted to have a reference of what the pre sounded like - vocally - with different combinations of transformers and op amps, so I could determine what might work best for something that I was working on.

This was as "controlled" as I could get in the room that I am in. I'm not in a lab or an anechoic chamber, so the results of this might not meet your own criteria for a controlled environment.

The thing that I'm not sure of, is if I have the room left on my SC account to make all of these .wav files. I might have to limit this to MP3's.

I'll up load to SC and start posting within an hour or so.

paulears Sat, 02/28/2015 - 05:11

What would be good would be to use a common recorded source - maybe something pure like a sine wave, and then maybe a square wave. It would be interesting to see if the different preamps introduce something other than gain - distortion and harmonics would be fairly easy to spot. It would also be possible to look at the noise levels. I'm very interested in the differences between them, but (as I guess I'm a bit of a sceptic) I'd like to see real evidence rather than subjective stuff. We all hear differences, we've done this before, but we always seem to disagree on what exactly is 'better'.

I've had an ear infection for a while now, and while I've had it, all my studio work has been off - I'm having to do most of the mixing again. While I had it, my impression was I lost the top end, which I compensated for, but now I'm discovering the mixes and the eq are just wrong. I expected that the mixes would just be too bright, which I could compensate for. However, the whole sound is just wrong. So maybe, what the preamps do is not just frequency response and they do other things. Any kind of result that is objective would be very useful. Just not quite sure how to do it. Donny's done a great job so far - maybe I can collect the same sound with all my preamps - please note, no truly posh ones, because I'm a non-believer, but I do have all sorts.

Any suggestions for what the test tones could be?

DonnyThompson Sat, 02/28/2015 - 05:28

paulears, post: 425573, member: 47782 wrote: What would be good would be to use a common recorded source - maybe something pure like a sine wave, and then maybe a square wave.

Well, I agree with you that it would probably be more accurate, scientific. It would be easier to measure distortion. and if I was building one, I'm sure it would be necessary to use those types of stimulus to determine the things that matter in the specifications.

But - as artistic users of the gear, we don't record or mix square and sine waves: we mix music - voices, instruments, those things that our ears find musical and pleasing.

Personally, I'm able to relate a lot more to how a pre sounds using a vocal or acoustic guitar, than I am a sine wave.

Yes, one is certainly more scientific than the other - but far less artistic and pleasing to the ear. I want to be able to hear how things like breath, and "S's" sound on a certain pre, certainly more than how a square wave does, because those are the nuances I work with and listen for in my everyday mixing.

Just my opinion. ;)

paulears Sat, 02/28/2015 - 05:50

Good opinion, just my perhaps unique viewpoint. I just wonder if the reason I just can't get into this pre-amp thing is that maybe what I get from eq and processing could be the same thing - a difference in tone/timbre/overall sound? If I bought a preamp and discovered I liked what it did, then I'd want to know what it was actually doing - when we went digital, people didn't like the sound, so started to develop plugins and stand alone devices to simulate the old sound.

All the little tricks people do, like replacing capacitors in condenser preamps in the mic, result in 'something' changing, and I'm curious enough to want to know what it is?

The mics I sell have samples of how they sound on common instruments - nylon and steel guitars, saxes, clarinet etc - and just recently I had to re-record them because I lost the little spreadsheet that told me that 123.wav was a specific mic. I tried to work it out by listening, but couldn't. They were different, but in the end, I gave up.

I'm getting the impression that if I do the tone test, I might actually reveal errors in the preamps I use on a daily basis. That would kind of contradict my feeling on preamps.

paulears Sat, 02/28/2015 - 05:57

On the samples - my preference is 4,3,1,2 I like 4 best because it is warmer and gentler. 2, the one I prefer the least, would still be perfectly acceptable if I didn't have access to the others.

I've also got a problem. The difference is far greater than I'd imagined, and this suggests my own selection of less 'posh' ones could be equally coloured. I've never done an A/B, just recordings on different sessions and sources. I'm going to have to listen to those again on some different kit and see if the order remains the same.

DonnyThompson Sat, 02/28/2015 - 06:10

By no means am I suggesting that you shouldn't do the test you mentioned, Paul - I absolutely do think you should.
(LOL- someone has to do this kind of research...)

I'm just saying that for me, the end result is the musical sound I hear - I have a far less scientific approach to my testing methods, because I want to know how these different components will sound in a way that relates closer to how I hear and work with sonics as an artist.

For example, there maybe painters out there who really want to know why a particular shade of blue is what it is... the source of the primary color; maybe a certain plant, mineral, or chemical addition... and then there are those who simply say to themselves, "hey, I really like this shade of blue, I think I'll use it on this painting." They don't care as much as to the "why", they care more about the "where".

And, it's probably very short-sighted of me to approach it this way. But, I can only go by my own set of criteria, which is what I hear - and relating that to how I would use it.

There could be a case where, technically, a measurement might indicate that one op amp was technically superior to another, but I'm not sure that this would mean - to me, anyway - that it would be a better choice for a particular production task at hand.

The Neve 1073 preamp, if you think about it in terms of technical specs, is dirty, distorted, and, by all technical specs shouldn't be a choice made by those who are concerned with these specifications... yet, it's become one of the most sought-after sounds in the last 40 years or so, because of the way it sounds.

For those who want a completely transparent sound, it's not a good choice - and technically, if you measured it, in terms of distortion, it should probably be a last choice - but artistically, it's become the first choice for many, because it sounds so great in the way that it distorts.

IMHO of course.

DonnyThompson Sat, 02/28/2015 - 06:52

paulears, post: 425580, member: 47782 wrote: I've also got a problem. The difference is far greater than I'd imagined,

Simply to confirm... absolutely nothing changed from take to take but the Op Amp.

No EQ, no GR, same mic, same position, same distance from the mic.

(Okay, yeah... so maybe my performances were slightly different from sample to sample, but I tried to keep the vocal short and sweet, singing it as close as I possibly could, in the same way each time).

I used one of my own songs so that it wouldn't be familiar to those listening, to avoid the possibility of causing listeners to be subconsciously - or even consciously - biased about their preferences, based on a song that they were already familiar with.

;)
d.

paulears Sat, 02/28/2015 - 11:01

Donny - not a problem with your recordings, a problem with my continued belief that mic pres NOT making much difference - it looks like I may have some re-evaluating to do. I'm expecting my own to have a similar broad set of differences, which is not what I have always believed. Probably have some time spare in the week.

pcrecord Tue, 03/03/2015 - 08:11

paulears, post: 425578, member: 47782 wrote: I just wonder if the reason I just can't get into this pre-amp thing is that maybe what I get from eq and processing could be the same thing - a difference in tone/timbre/overall sound?

paulears, post: 425580, member: 47782 wrote: I've also got a problem. The difference is far greater than I'd imagined, and this suggests my own selection of less 'posh' ones could be equally coloured. I've never done an A/B, just recordings on different sessions and sources

I know preamps are not your thing Paulears. I respect that! It is very true that good recordings could be done with many different low to highend preamps. Many will consider the difference to be a mith.

Quality preamps made a big difference for me on my recordings and the most obvious difference is that I don't need to use drastic EQ like I did with the preamps included in my interface. I can rationally categories them in 3 categories : Consumer, Pro-summer and high end.
Here is my own classification (nothing scientific, just opinions and expériences)

  • Consumers, would be many budget micro mixers, cheap preamps (Under 50$) and many budget audio interfaces.
  • The pro-summer are all mid level gear ranging from 50 to 400$ per channel. Many mixers for live and studios.
  • HighEnd : those units with dedicated preamps ISA, ADK, Grace, Millennium, API, Neve etc...
class="xf-ul"> Thing is, once you've tried one, you just go 'Ok, that's the thing !!!'
You don't need to have one, but with them, my life got easy !

pcrecord Tue, 03/03/2015 - 08:22

DonnyThompson, post: 425581, member: 46114 wrote: The http://www.rupertne… Neve 1073 preamp, if you think about it in terms of technical specs, is dirty, distorted, and, by all technical specs shouldn't be a choice made by those who are concerned with these specifications... yet, it's become one of the most sought-after sounds in the last 40 years or so, because of the way it sounds.

True, but on the other hand, neve clones are not so dirty that you would think (ex Vintech 1073)
It depends how you drive them ;)

DonnyThompson Tue, 03/03/2015 - 09:40

pcrecord, post: 425700, member: 46460 wrote: Quality preamps made a big difference for me on my recordings and the most obvious difference is that I don't need to use drastic EQ like I did with the preamps included in my interface.

I agree with this, I've found the same thing - that when using this ADK, I end up using far less EQ to "sit" those tracks into a mix than I did when I was using cheaper pre's.
I don't think it's a small thing, either...it's definitely one of those "oh, yeah... there it is" kind of moments, as opposed to using cheaper pre's where it seems like I'm having to endlessly tweak, never getting exactly how I want it.

I don't think that there is anything wrong with some of the lower priced pre's - technology has come a long way since the days of absolute crap vs absolute pro. I'm not sure that, even 12 or so years ago, you could have gotten as good of a pre as the entry level Focusrites or Presonus's without paying pretty big money for them.

Perhaps the biggest thing I've noticed in difference, is that cheaper pre's seem to be okay - as long as you don't push them.

When using "budget" preamps with lower output dynamic and ribbon mics, even if it has enough gain (60db or better), when you gain them up to an acceptable level, you're also getting quite a bit of noise with it, too....

I've had this ADK wide open, and it's whisper quiet... dead silent. I hear nothing but the mic.

pcrecord Tue, 03/03/2015 - 16:24

My order is 2 - 4 - 3 - 1
I'm all thinking into context which we don't have here
I guess I find number 2 having the less EQ characteristic and I chose it because of it's potential versatility
I feel the num 4 has a bit more air and the 3 has more bottom
but the num 1 is just a bit thin

4 valid and usable takes ! It would be easier to choose depending on the instruments and arrangements of course

Boswell Wed, 03/04/2015 - 04:59

I haven't been able to listen to the different op amp versions in the studio yet, but hope to do that this evening or tomorrow. Don't let that hold up your posting of the varied transformer versions!

Which transformer did you use for the op amp changes, and which op amp are you using for the transformer changes?

When we have voted on the preferred op amp and preferred transformer, would it be feasible to have a sample with those two fitted if it was not one of the combinations already done?

DonnyThompson Wed, 03/04/2015 - 05:13

Okay...

For every take, I used the same transformer, a Sowter 9820. The Op Amp was the variable:

Test 1: ADK "Vintage" Op Amp
Test 2: Cinemag CM-1057
Test 3: Seventh Circle Audio SC25
Test 4: John Hardy 990 C

Reminders:

I sang the same 8 bar, single voiced verse of a song that I wrote. This takes out the bias of any familiarity of a song that you've already heard.
I sang it into an http://www.shure.co… SM57 on a stand, with the mic position never moving.
I did my best to remain the same distance from the mic - three to five inches distance, on axis, every take.
The input level on the pre was set at 50%
No gain changes were made on the pre at all. Nor was there any gain changes made on the line in of the Presonus. The gain control remained in the exact same position on both for every take
There has been no EQ added at all, either on the way into the DAW or afterwards
The same goes for gain reduction.
The only variable was the op amps used.

DonnyThompson Wed, 03/04/2015 - 05:23

@Boswell @pcrecord @Chris @paulears @dvdhawk

I'm going to upload the next batch later today.

But I'll wait until you guys tell me what you want as the variable on this next batch - Input Transformer or Op Amp? If it's the input transformer, do you want to know which Op Amp I'm going to use as the constant? (See list above)
If you'd rather have me change up the Op Amps again, I'm not gonna say which IT's I'll use - until the test is over and results are in.

Boswell, post: 425722, member: 29034 wrote: When we have voted on the preferred op amp and preferred transformer, would it be feasible to have a sample with those two fitted if it was not one of the combinations already done?

Of course. My aim is to make this test as complete and well rounded as possible.

DonnyThompson Wed, 03/04/2015 - 07:07

@pcrecord @Boswell @paulears @Chris @dvdhawk

I'll give this until about 4pm (EST) today for others to weigh in.

If no one suggests otherwise, I'll follow Marco's preference, and choose either the JH990 or the Seventh Circle SC25 as the op amp, and use the input transformers as the variable quotient.

Everything else - the mic, the song, the performance (meaning the section of the song I used) the preamp gain level, etc., will all remain exactly the same as in the previous round of tests.

-d.

Boswell Wed, 03/04/2015 - 15:57

Great tests, Donny! My vote would be for using the JH 990C when trying the various transformers.

Doing it this way doesn't take in the possibility that certain op amps perform their best with a particular transformer, but I hope we can creep up on that one when the transformer results are in. BTW, you may have to change the gain settings if the transformers have differing ratios.

dvdhawk Wed, 03/04/2015 - 19:54

Nicely done Donny!

There really isn't a dud in the bunch. It just goes to show that every variable contributes something (sometimes subtle, sometimes not-so-subtle) to the end result. They all have a distinct character, but none of them sound bad in any way. Anybody that can't cut a vocal track with any of them should consider a career drivin' the big rigs or something.

DonnyThompson Thu, 03/05/2015 - 02:13

So then.. just to confirm... you want me to use the John Hardy as the Op Amp, with the various input transformers as the variable quotient, right?

@Boswell
Bos, are you sure you want me adjusting gain input? I'm just asking... I would think that gain differences between the trannies would be something we would all like to know about?

But I'll be happy to do it however you guys want me to. ;)

Boswell Thu, 03/05/2015 - 02:56

DonnyThompson, post: 425758, member: 46114 wrote: So then.. just to confirm... you want me to use the John Hardy as the Op Amp, with the various input transformers as the variable quotient, right?

@Boswell
Bos, are you sure you want me adjusting gain input? I'm just asking... I would think that gain differences between the trannies would be something we would all like to know about?

But I'll be happy to do it however you guys want me to. ;)

No, I don't have any information either way. I was pointing out the possibility that the transformers may not all have the same turns ratio, and that may have to be compensated for in the gain settings.

However, if it's ADK that supply these transformers as a set of plug-in alternatives for their pre-amp, it would be odd if they didn't go the full mile and specify them all to be the same effective gain by patching in resistive dividers where necessary.

DonnyThompson Thu, 03/05/2015 - 03:41

ADK only supplies two stock components - an ADK Input Transformer (no other description, no model number, etc), and an ADK "Vintage" Op amp.

The others were purchased separately by the previous owner, although I'm guessing that some kind of coordination between the companies was necessary, in order to insure that the various Transformers and Op's pins were able to match the mounting receptacles in the AP1 - unless there are other channel strips, compressors, etc., where these pins match up the same way - I suppose what I'm saying is - and what I'm not sure of, is that perhaps all the various transformer and op-amp manufacturers have this mounting ability with other company's models already, and APK just made sure that their preamp fit that criteria ? I don't know... you'd know better on something like this than I would, Bos.

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