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
@Boswell @dvdhawk @Davedog Boy, this one's tough. Even knowing
Boy, this one's tough. Even knowing which is which, this is a hard one to choose. I don't think that there's any doubt about the quality of the JH990c Op Amp. It's a winner.
I hadn't realized just how many different mic preamp manufacturers offer the JH990 as an option for their gain staging - Focusrite, Amek, Eisen, Lola (both 500 Series Mic Pre's) ..
I understand that the original intent of the 990 was as a sort of API 2520 knock-off, but to my ears, it has its own thing going on. Having heard and worked with more than just a few API 500 Series preamps over the years, to my ears, the API's seem to be much more "mid-forward", whereas the 990c has a more "all encompassing" kind of sound to it... so I don't really understand why guys are looking at the JH990c as an API "clone". I'm not saying that one is better than the other - but after having used the 990C, I'm not really hearing as much "API-ness" to it as others seem to. I dunno, maybe it's just me that feels this way. Obviously, quite a few respected engineers feel otherwise, so take my statement for what it is - strictly an opinion, based on what I've heard.
IMO, if there is any Op Amp ( that I've used) that seems to come closest to the "API sound", the SC25 (Seventh Circle Audio) seems to mimic "that" sound ( at least to my ears, anyway.)
But... as far as the input transformers go, listening back to the various test samples, I like certain things about each of them.
I don't believe that any one of them sounds "better" than the others, per se', just different.
As Hawk mentioned previously, I'd be satisfied to get any of the above vocal tracks to work with; there's not really a "weak" one in the bunch, it just depends on what you like, and of course, completely within the context of whatever you were working on at the time - song, style, vocalist, mic, etc.
IMHO of course. ;)
d.
Just thought I'd throw in my thoughts on this since I own an ADK
Just thought I'd throw in my thoughts on this since I own an ADK AP-2 and also have a collection of trans and op-amps for this. I've been using mine for quite a few years now and it is most definitely the most versatile of any mic pre I've ever seen. The problem from the beginning is the theory that someone would unscrew the pre from the rack to change out the socketed components. Mine is attached to a rack tray like you'd find in a rack array in a computer room. They put those every 3 or four racks so the techs have a table to use for tools,writing tablets etc. Larry had a great idea with this pre just didnt finish the thought. I have Hardy's, API 2520's, three of the stock ADK op-amps (yes there's four I think...one 'vintage with an N, one vintage with an M and the DOPA1 and another I don't remember). There were also Fred Forssell 992's, Avedis 1222,Millennia MM99, and Melcor 1731 op-amps built to fit this configuration.
I keep forgetting to mention that most of the design and implementation of the innards came from A-Design's John Erikson
I also have a collection of transformers...Sowter 9820c, Lundahl 1538xl, Cinemag, Jensen 110,and stock ADK C1's. The stock ADK's are Crimson's. And I use all of them on certain sources. At this time, with my other rack gear, I have one side (AP-2 is two channel) set up with 990 Hardy amp and a Lundahl. Clean and wide range. I use it for acoustic guitars, and bass that needs articulations for fast passages. The other side is my go-to for bass on most tracks. I use the stock ADK Vintage with an N and a Sowter. According to Larry of ADK, the N is for Neve.
Its a good test Donny. The one thing I will add is the transformers make MUCH more difference in sound than the op-amps in most cases. The Op-amp differences are subtle and they are different, but the difference between a Jensen trans and a Lundahl is much more telling, though, I will say, the Hardy op-amp is different than all the others in so many small but significant ways on certain sources.
Carry-on.
@Davedog Thanks Dave. ;) Do you have a particular preference
Thanks Dave. ;)
Do you have a particular preference for IT/OA combination for 6 string acoustic guitar, using a 414EB?
At present, I don't have the AP1 racked, I have it sitting on a desk surface next to my mixing position.
If I were going to keep this though, I would definitely come up with something more permanent, where the unit was secure, but that would still allow me quick access to swap the components.
I'm finding out the same thing that you mentioned - in regard to the IT making a bigger difference than the OA - although I suppose that it's relative as well, depending on vocalist, song, etc.
Talk about tough! Unlike the op amps, these transformers are jus
Talk about tough! Unlike the op amps, these transformers are just different rather than better or worse. Given the mic, the op amp, the room and (of course) the voice, I marginally prefer the sound of #1A over the other 3, but any of them would work for me on that song.
Huge thanks for putting these tests together, Donny! Don't say you now have to do it all over again with an acoustic guitar?
I like them all and its the voice of the instrument itself that
I like them all and its the voice of the instrument itself that determines which combo gets used. In the ADK I tend towards the Hardy 990 and a Lundahl for most acoustic guitars. But understand, I also have a Manley DMMP , a Phoenix Audio DRS Q4, a True Systems P2, and a Focusrite428 that usually get used on acoustic guitars before the ADK.
I had some time spare this morning - cancellation last minute! -
I had some time spare this morning - cancellation last minute! - so I gave my idea for a waveform comparison a spin, and frankly, I can't reconcile the results at all. I generated a harmonically rich waveform in a synth - a square wave with some slight filtering - which gave a squareish waveform with some harmonics on the leading edge. I loaded the wav file into Sound Forge and inspected the result. I then replayed this into one of the studio monitors, and placed a microphone 2 feet in front of it, and then recorded the output via the preamp in the Tasacam multichannel interface in the rack, and also using the preamps in the Behringer X32 I have. I was expecting some obvious impact from the fact the signal had been amplified, fed to a loudspeaker and then re-recorded via a microphone. However, as any artefacts from this process would be the same on both preamps, I would be able to see the difference. I expected subtle differences in perhaps how a preamp dealt with the sharp transient, and the harmonics - but the visual result leaves me at a bit of a loss.
The original waveform, recorded direct internally is the middle trace. The top one is the Tascam and the bottom one the X32.
Anyone care to guess what on earth is going on. Listening to the audio, the X32 sounds similar to the original, but the Tascam sounds quite dull by comparison. I obviously need to repeat this with either voice and perhaps an instrument as well as the waveform under more controlled conditions, but this isn't at all what I expected. No tricks or processing - simply pressing record in Cubase, then changing the driver to the other device and doing it again. The only thing I did for the picture was to normalise the three files so they are the same amplitude to make the display easier to compare.
The waveform of the synth does have a visible slope, which is exaggerated in the X32 trace, but the Tascam is a mess!
Yep- it makes no sense whatsoever. In the room, the tone was con
Yep- it makes no sense whatsoever. In the room, the tone was consistent throughout, just what was recorded is bizarre! If I get a chance, I'll try to repeat it with multiple sources.
EDIT
The files were 44.1 16 bit - I chopped out the examples and transferred them to another computer to screenshot and upload the image - this is where the mp3 came from, the test and the observation was on uncompressed files.
@paulears @Boswell I'll just give a rundown of what I would th
I'll just give a rundown of what I would think.. and please don't take any offense, as I'm sure you are already well aware of what I'm about to mention...
I'm just kinda thinking out loud here ( it's just my own way of processing things) and not inferring that you don't know these things...
My knee-jerk reaction, my first inclination, would be that it has to do with conversion - would this difference reflect the different converters in the two i/o's? Could they really be that far apart in quality?
Mic pres? Could there be that much difference in the preamps between the two?
(Personally, and having used them quite a bit, Tascam preamps never impressed me)
There was no built-in limiting on the Tascam? ( i know a few pre's have this function, usually a button)...
Mic type and mic position exactly the same for both?
SR exactly the same for both, including bit resolution...
You didn't happen to have any kind of "feedback loop" occurring with the Tascam?
What is happening sonically, Paul..? I mean, when you actually listen to both... are you hearing anything in particular that sticks out on the Tascam? Any obvious, audible artifacts at all?
Donny - no offence whatsoever, I'm extremely confused as to inte
Donny - no offence whatsoever, I'm extremely confused as to interpreting the results. The audible difference is that the Tascam is duller - and the 'zing' the harmonics in the synth tone have are not very pronounced while the X32 sounds very similar. Test condition were physically no change to positioning, the XLR from the Tascam being removed and connected to the rear panel on the X32.
I think I need to repeat this using a separate system for replaying the tone. Something is wrong here, the difference is far too plain to be the expected preamp difference. Especially as the Tascam is actually my preferred device. Perhaps I can arrange two simultaneous recordings of the same sound source - I'm thinking mic splitter. I'm lucky enough to have standardised my studio computers, buying identical ones (Carillon rack mounted PCs), so I will give it a go when I get another spare slot.
I could then have twin track stems, one with one preamp one with the other, perfectly time aligned?
as opposed to using a splitter - I'm just saying if it were me -
as opposed to using a splitter - I'm just saying if it were me - I'd use each of the synths outputs ( using a mono patch like a saw wave synth or something) and send each out to the mono ins of each of your I/O's, taking the mic/speaker part out of the equation entirely.
Oh... wait... are you using an external synth or a VSTi for this?
Okay, how about this: using two identical mics - like 57's, or 58's, and putting one mic on the right monitor, using another on the left, trying to get them placed at each speaker as identically as you can...
Then send one mic to one pre, one to the other, and record.
I'm trying to find an alternative to using a splitter...
The synth is a vsti, exported as a .wav. Maybe I'll try a couple
The synth is a vsti, exported as a .wav. Maybe I'll try a couple of small condensers taped side by side and use one monitor, and then produce a twin channel recording, one pre on one side one on the other, that can then be edited as one? I could try voice, instrument and replay of the synth tone? I will have a think.
I've had some strange results. I set up three identical mics. Ca
I've had some strange results. I set up three identical mics. Cardioid condensers, from a batch I import from China. I spent some time a while back selecting half a dozen at random that seemed a good match - they're pleasant sounding mics, and I use them for radio, conferences, big band type stuff. 3 mics on one stand - feeding the X32, the Tascam (a 1640) and because it was sitting there, a Zoom H4N. On my voice, the X32 was nicest, the Tascam just a wee bit brighter. The H4N was a little lacking in substance, but I had to discount it's part in the test as I ran it off a power supply with a hum! (of course, didn't notice until too late)
I'd not noticed, using them one at a time that there was indeed a difference in the sound of the preamps (my notion that all I wanted was gain being shattered). I liked the X32 in preference to the Tascam, a difference I did not expect. I recorded voice, and a few instruments and then some synth sounds. I placed them all on a Cubase timeline, and then discounted the Zoom, for the hum. I exported the X32 and Tascam as a stereo file with one on the left and the other on the right. Looking at that file in Sound Forge it was a clear the actual waveforms were quite different, once expanded and studied. Sound wise, I hear subtle differences, not huge differences, but visually they are different. Definite changes to the waveform when studied closely. Not as obvious on voice, but on synths and sustained guitar notes, they don't look the same. Recording an open string on the guitar from the pluck to it dying away, there is a small difference in the sound - perhaps described as hardness in the Tascam, but clearly the waveforms show more detail in different areas.
If anyone else gets a chance to try this test with a repeatable sound (hence why I used a synth) it would be interesting to see if their results are the same as mine. I need some proper time to set up this test again and see if I can get repeatable results.
I'm not sure it proves much, other than I now have to agree with the people who told me how different preamps sound, and I can hear it. Not certain it's sufficient for me to stop using the Tascam, which I still like, but when the X32 is available, I think I may use it if the size isn't going to be a problem.
good on you Paul. it's common sense. different amps using differ
good on you Paul. it's common sense. different amps using different topology are going to sound different. fender amps sound different than peavey amps. why? because they are different designs.
DonnyThompson thnx for the Hardy snip .... cool stuff.
@paulears @Kurt Foster @Chris @Boswell @Davedog @dvdhawk The w
paulears Kurt Foster @Chris Boswell Davedog dvdhawk
The whole idea of this thread was for learning purposes.
It doesn't really matter if we all learn different things. Maybe you learn that different preamps do sound different... maybe you learn that you don't hear the differences as being worth it.
Maybe you simply don't like what you hear at all. Maybe you learn that you prefer a preamp without a transformer, maybe you learn that you actually do hear a difference when you'd previously thought that you didn't or couldn't.
There's no wrong way of learning in this situation. You take away from it what you need, and apply it to your own situation.
As far as I'm concerned, that's what the purpose of a forum like this should be about. I shouldn't be me saying "here's this pre and you're nuts if you don't like it."
To the contrary, it should be more about me saying "Okay... here's what I have, here's what I used, here's what I did, and here is the context of which this was done. I present it to you so that you can hear it and make your own decisions."
I did my best to approach this thread with that type of presentation in mind. ;)
d.
DonnyThompson, post: 425876, member: 46114 wrote: @paulears @Kur
DonnyThompson, post: 425876, member: 46114 wrote: paulears Kurt Foster @Chris Boswell Davedog dvdhawk
The whole idea of this thread was for learning purposes.
It doesn't really matter if we all learn different things. Maybe you learn that different preamps do sound different... maybe you learn that you don't hear the differences as being worth it.
Maybe you simply don't like what you hear at all. Maybe you learn that you prefer a preamp without a transformer, maybe you learn that you actually do hear a difference when you'd previously thought that you didn't or couldn't.There's no wrong way of learning in this situation. You take away from it what you need, and apply it to your own situation.
As far as I'm concerned, that's what the purpose of a forum like this should be about. I shouldn't be me saying "here's this pre and you're nuts if you don't like it."
To the contrary, it should be more about me saying "Okay... here's what I have, here's what I used, here's what I did, and here is the context of which this was done. I present it to you so that you can hear it and make your own decisions."
I did my best to approach this thread with that type of presentation in mind. ;)
d.
This should be put into the About Us and also made as a sticky. PLEASE! Lets word this until we have it exact and then do that okay?
IMHO, this is ALL why we should post here.
I'd love to hear the difference between your pre's! :) Why woul
I'd love to hear the difference between your pre's! :)
Why would you need 4 identical mics, pal?
IMO, you are far better off using the exact same mic to record each one of your samples. You want to keep the variables in the equation down to just one thing - in your case, the preamps are the only variable.
Just sing something, anything you want, into a 57, changing only your preamp from take to take. Do your best to make sure that the different takes remain as unchanged as possible... in terms of the performance - same space in the room, same exact position, same distance from the mic each time, same key signature, same gain, same charisma, etc.
I would ask that you start a new thread for it, though, so that each of our threads can remain focused on the original intent for each...or it might become too convoluted.
IMHO of course. ;)
Q; when converters age, degrade from heat overtime, which I've
Q; when converters age, degrade from heat overtime, which I've heard is already happening with Aurora's and... just guess, may happen with the Orion in time (32 channels packed into a one unit rack), get hot! Is it the op-amps that become inconsistent? The sound from channel to channel can be quite different from one to the next. Meaning, high freq loss on one channel, distortion on another, extra mid, weak mids... . Many people don't even notice these things but those little things actually compound into huge problems.
As an example that may make more sense, you can repeat a note on a sampler keyboard and as it switches to the next voice, the converters are not always the same clarity. This is no different with converters. This is why I prefer 8 channels per unit rack and each having adequate cooling and separate psu.
My point is, we need to be aware of the quality of converters, making sure they are tested to be "close enough"when comparing the simplest things like this. This may seem like converters don't matter, but I assure you, they do a lot more than most realize.
Imagine having a hybrid system, you have one converter on your bass channel that is weak, thus, always producing a bad low end. You blame preamps, mics, etc when it really is the simple channel on that converter that's been like that for years.
Which is why I think Kurt just nailed this! A least for more than I ever gave credit to a USB mic !
With a USB mic (quality doesn't matter for this, we are shooting for difference in another part of the chain) is going to be the same source no matter how many channels is needed. This removes any question about converter to converter effecting our comparison.
Chris, post: 425927, member: 1 wrote: But, haven't we had this d
Chris, post: 425927, member: 1 wrote: But, haven't we had this discussion a few times and each time Bos suggested a splitter box? Man, I'm loosing my memory. We need to make this a sticky when we figure this out.
A splitter box is one possibility, yes, but not a great one. It would work better with a condenser mic than with a dynamic.
With regard to using a recorded voice, I don't think it would work very well. Since there isn't the vocal equivalent of a player piano, you can't test the voice performance of microphones and associated pre-amps by having a mechanical source. More specifically, you can't reproduce a voice recording through a speaker into various microphone/pre-amp combinations and expect to get an accurate comparison of how those configurations sound with a real voice. The best you could hope for is to detect gross differences between them, since what you are effectively being asked to judge is how accurately the results sound like a voice being reproduced through a loudspeaker.
I didn't understand the USB mic reference. Oh...just a minute, I did - it's a joke. Sorry I took so long to twig.
Boswell, post: 425929, member: 29034 wrote: I didn't understand
Boswell, post: 425929, member: 29034 wrote: I didn't understand the USB mic reference. Oh...just a minute, I did - it's a joke. Sorry I took so long to twig.
no i was serious. i researched usb mics ... the Blue and Shure both make usb mics that have been deemed useable by some. i say get one that works ok and use it to record source tracks and then re amp them for comparison. another alternative would be to use a condenser mic with high output straight to track sans pre and then re amp. and it doesn't have to be voice only .... it can be anything ....
this has been a problem for us ever since i can remember. how to compare mic pres?
Kurt Foster, post: 425932, member: 7836 wrote: no i was serious.
Kurt Foster, post: 425932, member: 7836 wrote: no i was serious. i researched usb mics ... the Blue and Shure both make usb mics that have been deemed useable by some. i say get one that works ok and use it to record source tracks and then re amp them for comparison. another alternative would be to use a condenser mic with high output straight to track sans pre and then re amp. and it doesn't have to be voice only .... it can be anything ....
this has been a problem for us ever since i can remember. how to compare mic pres?
I'm glad you clarified that pal because I was going to hide under a rock for a month and try and explain what I was grasping from Kurt's suggestion beyond my post above, which appears to mean little in this topic so far. :ROFLMAO: Bowing out while I'm still fairly reputable :p.
DonnyThompson, post: 425938, member: 46114 wrote: I'd kinda like
DonnyThompson, post: 425938, member: 46114 wrote: I'd kinda like this to eventually veer back towards the original topic, gang...
it sort of is relevant though, as we're just a bit off the trail while we sort out the constants, no/yes? Bos is here, he will no doubt swing us back on track. (y)
maybe results now? I actually liked a, b, c but why didn't I li
maybe results now?
I actually liked a, b, c but why didn't I like d?
Note: It had the exact same irritant that I've mentioned on a few other examples of yours. Its almost a slight comb/ loopy tone that lives around 4k to 8k. You mentioned it being vocal chord nodes before but why do I not hear that on the other three as dominant?
Kurt Foster, post: 425932, member: 7836 wrote: no i was serious.
Kurt Foster, post: 425932, member: 7836 wrote: no i was serious. i researched usb mics ... the Blue and Shure both make usb mics that have been deemed useable by some. i say get one that works ok and use it to record source tracks and then re amp them for comparison. another alternative would be to use a condenser mic with high output straight to track sans pre and then re amp. and it doesn't have to be voice only .... it can be anything ....
this has been a problem for us ever since i can remember. how to compare mic pres?
The joke was on me, after all - sorry.
That said, I don't think the mic-record-reproduce technique will work as a sound source. What you need is a sort of distribution amp but for microphones, so you can sing through a single mic into many pre-amps at once. However, any active component in the path is going to colour the result, which is why you need a single source that you can connect to several pre-amps. Maybe a high-output condenser mic that is able to drive a 600 Ohm load would fit the bill. Your U87, Donny?
@Chris @Boswell @pcrecord @paulears @dvdhawk @Davedog Sorry guy
@Chris Boswell pcrecord paulears dvdhawk Davedog
Sorry guys, I got hung up replacing a sump pump yesterday.
Summary of tests:
Mic Pre: ADK AP1
Mic: Shure SM57
Distance from mic: 3-5", (average, 3".)
Op Amp: John Hardy 990C
Input gain at 50 %
Line Out to Presonus VSL1818 Line In (no added gain on Presonus. Input at Line Level).
Here are the results:
Input Transformers were as follows:
Test 1A : Jenson JT110K
Test 2A: Lundhall 1538XL
Test 3A - Sowter 9820
Test 4A -ADK Cinemag
Some research has shown the following details about each IT:
A higher ratio gives you more noise-free gain, but there's also a proportional relationship between a transformer's turn ratio and its fidelity. High ratio transformers generally don't perform as well as low-ratio transformers.
The stock ADK/Cinemag transformer has a wind ratio of 1:8 (turn ratio)
The Jensen 110K also uses a 1:8 ratio
The Lundhall 1538 was commissioned by Rupert Neve for the Focusrite ISA Console.
From Lundhall: " The LL1538 and the LL1538XL are high performance microphone input transformers, each with a high permeability mu-metal core and two three-section coils.
In the LL1538XL the core is about 45% larger than in the LL1538, resulting in a larger level capability. In both types, primary and secondary windings are separated by electrostatic shields."
Deane Jensen developed his line of transformers while working for Quad Eight, a console manufacturer, in 1968. He determined that the primary source of poor sound of many consoles at the time lay in the input transformers.
He re-designed existing transformers, as well as designing and building his own, implementing The Bessel Curve Filter: this is a type of analog linear filter with a maximally flat group/phase delay (maximally linear phase response), which preserves the wave shape of filtered signals in the pass-band. Bessel filters are often used in audio crossover systems.
From Jensen: "Deane re-engineered transformers to increase the frequency response and introduce the Bessel curve that Jensen is famous for; in 1974 he officially started Jensen Transformers Inc. He then introduced models with double Faraday shields for noise rejection and came up with rapid QC testing of core materials, part of the “special sauce” that continues to this day. Jensen Transformers quickly became a benchmark of the audio industry."
The Sowter 9820c was designed as a clone of the API 312 IT. The primary has 2 equal 150 ohm windings which can be used in series or parallel for 600/150 ohms input. ratio 1:4.4 or 1:8.8. 100% mu metal core and can.
FWIW
-d.
Great! Thanks, Donny. I'll have some fun listening to those toni
Great! Thanks, Donny. I'll have some fun listening to those tonight.