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Author Topic: Any Starter Mics with Vintage Sound?  (Read 7984 times)

Jim Williams

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Re: Any Starter Mics with Vintage Sound?
« Reply #15 on: July 23, 2014, 10:44:02 am »

An alternative is one of those cheapo Chi-com mics with a replacement capsule and perhaps replacement circuit parts or pcb.
The mics tend to sell for around $50~60 or so. The capsules (k-47, c-12, k-67, etc,) sell for around $100. You will need to invest about $200 total into this if you do your own work.

I have about 15 of the older MCA SP-1 mics I bought for $39 each. Each has a k-47, k-67, k-87, k-7, k-1 and c-12 capsules, all are usable and sound very good for the $ invested.

If those capsules are not good enough, there are plenty of higher priced versions available as well. Once you have the mic bodies set up, you can swap capsules all day long.
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polypals

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Re: Any Starter Mics with Vintage Sound?
« Reply #16 on: September 04, 2014, 05:31:41 pm »

Maybe look at what the TS is using now will make a suggestion to improve the quality of his recordings within budget easier.
What about a nice omni dynamic mike from a well known manufacturer like Sennheiser?
The MD 21 will no doubt be an improvement on what he is using now.
These mikes go for 50- 100 usd in Europe. They were standard equipment in the sixties and seventies for reporters using Nagra III an IV portable recorders.

Nothing against the SM 57 but the old Sennheiser beats the Shure mike anytime.

Vintage is a term meant for items going back to the twenties of the last century.
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Mickeyrouse

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Re: Any Starter Mics with Vintage Sound?
« Reply #17 on: November 21, 2014, 08:16:14 am »

If this thread hasn't grown cold, I'd like to comment on Kai's frequency range analysis of the Shure SM-57. First of all, how representative of ALL SM-57's is the picture? It may be fairly consistent throughout the production run, but without statistical sampling it is not necessarily indicative of what the consumer may find.
   And as it has been noted here before, one should be wary of over-reliance on performance stats from the mfg'r as predictive- I have done it myself since I started devouring such specs in the early 60's.
      Yet I still believe that performance data can be helpful, it's just that as mic consumers we don't receive it. I'm talking about a  distortion curve over the usable audio spectrum, and figures on transient response. Published distortion data is almost universally provided as that amount of THD found at 1000 hz. My Neumann mics almost without exception carry published specs of .05% at that frequency. Comparing this to figures offered by other manufacturers makes me feel all warm and fuzzy.
        But I wonder: what's this or that mic doing down around 100 hz, or 400, or- well you get the picture. And what kind of distortion? Even-order or odd-order? Which harmonics?   And then- is distortion of a certain kind at a given frequency of a particular amount bad- or is it good? 
      We have come to learn that the Gain knob on some pieces of gear increases negative feedback which increase marginal (or greater) amounts of distortion, and we think we like it in some cases. Yet if we knew what kind, and how much, and where, we could make more informed decisions about just why we may like or dislike one mic versus another.
        Transient response is another performance point.  Neumann via their forum has provided me with a technical article discussing transient response in mics, particularly comparing TR in condensers (which?) to dynamics (again, which?). Despite all kinds of issues that could be raised about brand, etc., I think it safe to say that the article pretty well makes the point that condenser performance versus dynamic performance is pretty impressive.
         Transient response data is available. While I have never owned or used any of their mics, Earthworks publishes transient response data.  All well and good, and I hope they continue to do so, but until industry leaders like Neumann/Sennheiser get on the TR bandwagon, comparability is not possible.
   One last observation re specs:  Neumann also told me that they lament the fact that there really are no industry standards for performance data. So...until there are standards, we should really take it all with a grain of salt.
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Jim Williams

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Re: Any Starter Mics with Vintage Sound?
« Reply #18 on: November 21, 2014, 11:23:42 am »

Complete THD tests are not available from any mic manufacturer. The reason I leave to their marketing departments, but it does ring of the current trend of "reliance on the stupid voter".

THD vs amplitude at 100, 1k and 10k plus THD vs frequency sweeps would tell many tales. Then there are the IMD tests that reveal transient distortions. Most would not be impressed by the results.

Many capacitor mics have THD issues in the low end, Neumann included. It's generated by an insufficient input impedance. AES had an article on this back in the 1990's. 200 meg ohms in a "vintage" tube mic will generate a high level of THD at 20 hz. 1 gig ohm lessens that, it's reduced to .001% at 10 gig ohms.

I have modified AKG 460 bodies here with a 10 gig ohm input impedance. Those measure .001% THD at 20 hz, best I've measured with the Audio Precision, it can be done.

"Industry standards" are created by the industry. All it takes is a few notable manufacturers getting together and setting those standards. Their apparent lack of interest in accomplishing that leads one back to "reliance on the stupid voter".
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Kai

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Re: Any Starter Mics with Vintage Sound?
« Reply #19 on: November 21, 2014, 12:43:12 pm »

I'd like to comment on Kai's frequency range analysis of the Shure SM-57. First of all, how representative of ALL SM-57's is the picture? It may be fairly consistent throughout the production run, but without statistical sampling it is not necessarily indicative of what the consumer may find.
I had taken an average sample of the 10 or so SM57 that I have, partly from different prod. runs.
There are differences, mainly in the HF range and the 6 kHz peak, but not too big.

...the Gain knob on some pieces of gear increases negative feedback which increase marginal (or greater) amounts of distortion, ...
Turning up gain (louder) REDUCES negative feedback in usual mic amp designs, and yes, distortion can become slightly higher then.
The effect is not very significant (in high quality amps) unless you set up quite high gains.
Transformer coupled designs have an advantage here, as the transformer delivers a voltage gain of up to 26 dB for free (I don't mean $$$, good transformers are costly), so the active electronic part has an easy life.

Regards
Kai
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Mickeyrouse

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Re: Any Starter Mics with Vintage Sound?
« Reply #20 on: November 22, 2014, 07:23:53 am »

Kai, I appreciate your observations, and what you observe with the Shure 57's is more meaningful having tested more than one. My point however, is that manufacturers have ( or at least, should have) meaningful performance data of the kinds I have mentioned. Furthermore, I believe it would be extremely helpful to conduct trully broad- baded tests on the classic pantheon of mics-u47. U49, C12, etc.  seeking audio sprectrum harmonic distortion tests at various SPL's, types of noise sources (pink, white, etc.) at varying distances from the source, plus transient response data.
  At some point I think we could further identify statistical attributes of what makes us like this or that mike.
     In fact, I volunteer to conduct the tests. Just send me your idle U47, U49, C12. Will probably take a little while, but they will be returned. I promise.
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Jim Williams

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Re: Any Starter Mics with Vintage Sound?
« Reply #21 on: November 22, 2014, 11:40:05 am »

Turning up gain (louder) REDUCES negative feedback in usual mic amp designs, and yes, distortion can become slightly higher then.
The effect is not very significant (in high quality amps) unless you set up quite high gains.
Transformer coupled designs have an advantage here, as the transformer delivers a voltage gain of up to 26 dB for free (I don't mean $$$, good transformers are costly), so the active electronic part has an easy life.

Regards
Kai

Most transistor mic amp designs don't vary feedback to adjust gain, they are mostly instrumentation amp topologies with gain adjusted between the sections. Some exceptions are older Trident transformer coupled designs that do vary feedback for gain adjustment. Those cause all sorts of variables in secondary loading creating ringing at lower gains and drooping at higher gains.

Transformer voltage gain is offset by insertion losses. -2.5 db is normal. Those topologies offer a maximum noise spec of -127 db EIN using a low ratio 1/2 design. Low noise transistor trans-amp topologies offer much better noise performance, up to -133 db EIN at 50 ohms. THD is also lower as low frequency transformer THD is avoided.
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Kai

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Re: Any Starter Mics with Vintage Sound?
« Reply #22 on: November 23, 2014, 09:07:19 am »

Low noise transistor trans-amp topologies offer much better noise performance, up to -133 db EIN at 50 ohms.
I've yet to see a real world (not theoretical) mic amp with -133 dB Equivalent Input Noise (RMS, unweighted) coupled to a 50 Ohms source.
BTW: 50 Ohms does make less sense than 200 Ohms, representing a dynamic mic.
When a condenser mic is connected, the mic's internal amplifier's noise is the dominant noise source anyway.
BTE: 2.5 dB insertion loss of the transformer is a far from an ideal design. There are designs with 5K input impedance (almost no loss) and still 26 dB (1:40) step up ratio, e.g. in the Mindprint DTC.

To come back closer too the oiginal question - in usual setups all these technical parameters are of minor importance.
In my opinion you cannot judge a mic's sound on measurements.
The frequency response gives you an idea of the "voicing" of the mic.
Most other measurable parameters are hardly, if at all, correlating to a specific sound.
Some, like max. SPL or directivity, can still be interesting to pre-judge if a mic will work OK in a specific situation.
Finally a simple A/B(/C/D) test with the candidates will usually show immedeately which one is better for the job to be done.
And then in comes experience - good technicians know what works, giving a good starting point for possible improvements.

SM57 works (in this price range)!
Sennheiser sometimes, sometimes not, but not the ones for 150 bucks.
My 2 cent.

Regards
Kai
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Jim Williams

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Re: Any Starter Mics with Vintage Sound?
« Reply #23 on: November 23, 2014, 10:58:01 am »

I've yet to see a real world (not theoretical) mic amp with -133 dB Equivalent Input Noise (RMS, unweighted) coupled to a 50 Ohms source.
BTW: 50 Ohms does make less sense than 200 Ohms, representing a dynamic mic.
When a condenser mi is connected, the mic's internal amplifier's noise is the dominant noise source anyway.
BTE: 2.5 dB insertion loss of the transformer is a far from an ideal design. There are designs with 5K input impedance (almost no loss) and still 26 dB (1:40) step up ratio, e.g. in the Mindprint DTC.

Regards
Kai

Most transformer coupled mic designs use a 150 ohm impedance, Europeans selected 200 ohms. Many transistor output mics are 50 ohms, some less. In that regard mic amp EIN specs at 50 ohms are useful. Some transistor mics have extremely low self noise around 3~4 db, couple that with a low noise mic amp and all the noises heard are random air movements, not electronic hiss.

150 ohms source impedance will give you a -129.6 db EIN, not too bad, better than can be done with a transformer like a JT-16 Jensen at 1/2 ratios. Run that at 50 ohms and it degrades as the noise matching of the transformer is lost. Bill Whitlock and Dean Jensen have AES papers on this subject if any readers want to delve deeper into that subject.

As to real world results, yes there are designs that achieve -133 db EIN at 50 ohms, The Audio Upgrades High Speed Mic preamp does -136 db with a shorted input, -133 db EIN unweighted that shows the true noise contribution of that design. All the noise that is heard are source contibutions from the transducer, the microphone. Transformers are not used as they would degrade those noise specs and severly decrease bandwidth and slew rates while adding low frequency THD.

Audio Precision measured THD is .0005%, IMD is 1.5 ppm, bandwidth is 30 mhz, slew rate is 2000V/us, output current is 110 ma, input impedance 4.5k ohms. It is an all current-feedback design that holds it's 30 mhz bandwidth even at +60 db of gain, all other voltage feedback mic amp designs will show a decreasing bandwidth with increasing gain.
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Kai

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Re: Any Starter Mics with Vintage Sound?
« Reply #24 on: November 27, 2014, 02:59:34 am »

...The Audio Upgrades High Speed Mic preamp does -136 db with a shorted input....holds it's 30 mhz bandwidth even at +60 db of gain
These specs are astronomic!
To come back to earth and closer to the topic - noise isn't too much of a problem today.
To have an advantage of such an, probably expensive, micamp you need:
- A very quiet room (no outside noise creeping in, no aircondition).
- The use of an dynamic or ribbon mic (the mentioned extreme low noise transitored mic's usually have a very high output, so the micamp isn't taxed too much).
- A very quiet source, otherwise you wouldn't need enough gain to make noise come into play.


Let's see what contributes to a good sound (in a given room with a certain artist):

The selection of a proper mic and good positioning of it, once you've done that you're 20% there.
Another 20% comes from the processing: EQ, compression, reverb etc., whatever is necessary.
Further 35% you get from working with the artist, giving him or her an inspiring headphone mix, give him the right feedback on his performance etc. etc. ... the whole story of conducting a recording.
14% you get from choosing the best takes and parts out of several runs.
Oops - only 1% left for the mic-amp  ;D

Depending on the performer and musical style the percentages may be distributed a bit different - plus - your milage may vary.
But in fact the artistic work is about half of the story.

Best regards
Kai
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polypals

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Re: Any Starter Mics with Vintage Sound?
« Reply #25 on: November 30, 2014, 07:48:34 am »


........BTE: 2.5 dB insertion loss of the transformer is a far from an ideal design. There are designs with 5K input impedance (almost no loss) and still 26 dB (1:40) step up ratio, e.g. in the Mindprint DTC.


Regards
Kai

If my memory serves me right 26 dB gain means 1:20 ratio.

Best noise figures I have met were 126 dB for state of the art preamps with stepup transformer.

These figures are of less importance recording music where we can count on relative high output from mikes. The SPL helps quite a lot.
I am not in the business of recording ants pissing against cotton.
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Kai

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Re: Any Starter Mics with Vintage Sound?
« Reply #26 on: December 01, 2014, 11:17:48 am »

If my memory serves me right 26 dB gain means 1:20 ratio.
You're right, Mindprint DTC has a transformer specially developed and made for them by Haufe. If I recall right it has a ratio of 1:20 (a gain of 26 dB), while maintaining very high input impedance (5K) and extremly broad frequency response (5 Hz-127 kHz).
Those guys at Haufe are real specialists!
See:
http://mindprint.de/cms.php?scr=show&tab=prod_anhang&id=7&r=p

Next time I service one of my units I'll take the time to measure the real values.

Regards
Kai
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polypals

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Re: Any Starter Mics with Vintage Sound?
« Reply #27 on: December 25, 2014, 05:19:09 pm »

A transformer does not have an input impedance, it simply converts the impedance it sees on one side to the other side according to the ratio of the transformer.

An input impedance of 5k is not the figure I would expect for optimimum noise figures.
It means the input impedance of the circuit following the transformer with step up ratio of 20 needs to be 1 Mohm.
I must admit I do not follow modern solid state developments but this does not look like an easy figure to achieve with minimum noise in mind.

Given the system of minimal load on sources as used in European professional audio 2 Kohm input impedance would be a more apropriate value.
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Kai

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Re: Any Starter Mics with Vintage Sound?
« Reply #28 on: January 04, 2015, 07:25:23 am »

A transformer does not have an input impedance, it simply converts the impedance it sees on one side to the other side according to the ratio of the transformer.
Yes and no.
A transformer is designed to work within a certain range of source and load impedances.
Outside of this range, specially at higher source or lower load impedance, frequency respose and sometimes even LF distortion figures suffer.

Otherwise you're right, the transformer even "transforms" the load and source impedance in the 2nd potence of it's ratio:
E.g. a 1:3 transformer transforms the connected impedance by a factor or 9 into the step up-, by 1/9 into step down direction.

An input impedance of 5k is not the figure I would expect for optimimum noise figures.
It means the input impedance of the circuit following the transformer with step up ratio of 20 needs to be 1 Mohm...
I works very well, I'll provide my own measurements ASAP.
As explained above the 1MOhm isn't the impedance the active electronic is shunted, but the much lower impedance that results from source impedance transformation.
The whole design was developed with by Mindprint in close collaboration with Haufe, who build this special transformer that is constructed much more complicated then usual.

The idea of this 5K input was to avoid damping of impedance peaks that can be found on dynamic mics, and I can say it works.
An Shure SM58 e.g. sounds brighter, more open on a DTC compared to any micamp I know.

Regards
Kai
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polypals

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Re: Any Starter Mics with Vintage Sound?
« Reply #29 on: January 04, 2015, 08:01:52 pm »

Kai,

5000x20x20 equals 2 Mohm load at the secundary of the transformer.
(You state the input impedance is 5Kohm.)

It follows the input impedance of the electronics is 2 Mohm.
Distortion does not vary as a function of the source impedance for low frequencies.
It is most of all dependend on power and frequency.
Power is low as long as the load of the source is ten times higher than the source.

I designed quite a number of inputstages as a young engineer.
The basics for good designs have not changed, components have but they are still based on laws of nature.

Input transformers are not rocket science with all due respect for Haufe.
By far the best input transformers I ever got my hands on were made by Studer.
These were used in the much improved green consoles designed by Polygram in the seventies.
Green followed the black generation that suffered from serious problems.
These green mixers were installed at Wisseloord studios in 1976.
They were superceded by SSL.
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