Low input from Sennheiser md421

lagartija

New member
Hey everyone,
I'm a newbie and just recently have acquired focusrite 2i2 and a used Sennheiser md421-n. Also, I have a copy of shure sm57 or 58 (gls es57).

I wanted to check whether md421 works ok (since this is a vintage mic and a new buy). This mic has Kleintuchel (din with 3 pins) connector, so I have to make a new cable (with DIN female and male XLR connector). The first time I got it wrong and there was a ground hum. On the second time, I think I got it right, as the sound was very clear and there was no noise. The source was just me talking rubbish ☺️

The only problem is that the input from md421 is low, compered to GLS (I use different standard xlr-xlr cable with GLS). I swapped the wires in pin (-) and (+), but that did not change much. I have to turn the gain on 2i2 for about 80-90% in order to match GLS (about 30% of the gain).

Is there a way to verify whether the md421 is ok? If it is not I would like to return it to the seller.

Thanks for any help. I really appreciate it.
 
I would expect most dynamic microphones to need most AI gains to be at 80% full gain or more (SM7b !).

That of course depends how you are testing them! "Mary had" at a foot or touching grill? Acoustic guitar at a foot? Ac git is generally not a practical proposition with any dynamic and bog S pre amp. But!

The specs for those mics are weird! The modern, XLR 421 seems to have a sensitivity of around -55dBV/Pa, rather better than a proper 57 at -58dBV. Mind you that 3dB difference would probably not be noticed in normal use and is quite close to acceptable tolerance. That GLS on the other hand is SAID to have a sensitivity of just -72dBV (they don't give the SPL) and that WOULD be very noticeable and make the mic pretty useless IMHO for other than a real screamer.

Bottom line then. If you can get acceptable levels and low enough noise, it ain't broke, weird but not broke!

Dave.
 
I would expect most dynamic microphones to need most AI gains to be at 80% full gain or more (SM7b !).

That of course depends how you are testing them! "Mary had" at a foot or touching grill? Acoustic guitar at a foot? Ac git is generally not a practical proposition with any dynamic and bog S pre amp. But!

The specs for those mics are weird! The modern, XLR 421 seems to have a sensitivity of around -55dBV/Pa, rather better than a proper 57 at -58dBV. Mind you that 3dB difference would probably not be noticed in normal use and is quite close to acceptable tolerance. That GLS on the other hand is SAID to have a sensitivity of just -72dBV (they don't give the SPL) and that WOULD be very noticeable and make the mic pretty useless IMHO for other than a real screamer.

Bottom line then. If you can get acceptable levels and low enough noise, it ain't broke, weird but not broke!

Dave.

Except for line two in your reply Dave, that was the most clear (in all languages) post I think I ever saw you post! LOL!


I can't offer much to the OP other than if it works, then it works. If it doesn't, well... Every microphone is different. Some need added gain to get it working well. I only have one Modern MD421. And oddly I use it for a ride cymbal mic. Not the usual, but it works. Actually the friggen mount for the broken mic clip was more than I payed for the mic itself...That was a shit design from the start!
 
I'm pretty sure most of those dynamic mics benefit from a preamp, prior to the interface. Cloudlifter is one I hear about. I had that issue with a sm58. I've also considered picking up a SM7b, so I looked into this awhile ago.
[MENTION=43272]Steenamaroo[/MENTION] might know more. If not, sorry Paul. :) We just discussed this a bit back.
 
Yeah, I think the md421 is hotter than some others but I'd still expect to be riding the gain high on most budget AIs.

Usually if there's a problem or a fault you lose bass as well as volume. The most common thing to go wrong with these big dynamics is for the whole coil and diaphragm to shift slightly, allowing the coil to rub.

Usually, if that happens, it's very obvious. Output would be very tinny and weak.

I have a pair of old kleintuchel 421n microphones myself. Lovely microphones. :)
 
Yeah, I think the md421 is hotter than some others but I'd still expect to be riding the gain high on most budget AIs.

Usually if there's a problem or a fault you lose bass as well as volume. The most common thing to go wrong with these big dynamics is for the whole coil and diaphragm to shift slightly, allowing the coil to rub.

Usually, if that happens, it's very obvious. Output would be very tinny and weak.

I have a pair of old kleintuchel 421n microphones myself. Lovely microphones. :)

And to add, I purchased two MD421's. The diaphragm was toast on one of them. It went in the trash as it was more expensive to fix than I wanted to upgrade to from it.

And yes, the 421 seems to have about the same output as an SM57. It does not need extra gain like a SM7b might. Just a decent signal to it.
 
Except for line two in your reply Dave, that was the most clear (in all languages) post I think I ever saw you post! LOL!


I can't offer much to the OP other than if it works, then it works. If it doesn't, well... Every microphone is different. Some need added gain to get it working well. I only have one Modern MD421. And oddly I use it for a ride cymbal mic. Not the usual, but it works. Actually the friggen mount for the broken mic clip was more than I payed for the mic itself...That was a shit design from the start!

"Damned with feint praise!" I cannot bloody win! That whole post would have baffled the guy with the noise! Even after I tried to explain in the simplest terms possible about earthing and how he might not be so!

I do not see what is at all obscure about the second line?

This HR game IS technical. I try to give accurate, straight answers WITHOUT, in the first instance, insulting the intelligence of the questioner. When said person does not understand a concept they invariably make some feeble joke, either slanted to me or themselves. They then give up, place back of hand metaphorically to forehead and say "oh! can't be doing with this!" Why?

I have plenty of time, I am willing and able to break down any response I give UNTIL the OP has a better grasp of the problem (might just save some expensive kit or, in the case of "noise man" save a life!).

I just don't get it? How did people get through school without application? If they "can't understand diagrams" how did they get around the country?(before Sat Navs).

This might be a "sound byte world" but electronics and sound recording takes a little longer to grasp.

An' another thing! Whenever you hear a truly virtuosic performance on any instrument that is the result of not just HOURS of practice but a big chunk of a lifetime. You just HAVE to do the work!

Dave.
 
This often repeater comment of get a cloudlifter plus the old mic topic made me remember something. With my old ferrograph and the sm57, unbalanced, jack plug connection direct toferrograph input - I could record birdsong outside my window. I used it as a wild track for a theatre show,meet in the countryside. I don't remember hiss being a problem at all. Where has this notion that dynamics are low output devices come from? 1970s preamps could not have been quieter than today's? Sm7 is also now commonly called a quiet mic, yet for decades has been connected to technically inferior than today's gear in broadcast and film? If something was boomable, as sm7s often were, how come we didn't get piles of hiss? If today's superior preamps need improving to use them, something suggests that modern preamps get their superior performance by having lower gain than the old ones?
 
This often repeater comment of get a cloudlifter plus the old mic topic made me remember something. With my old ferrograph and the sm57, unbalanced, jack plug connection direct toferrograph input - I could record birdsong outside my window. I used it as a wild track for a theatre show,meet in the countryside. I don't remember hiss being a problem at all. Where has this notion that dynamics are low output devices come from? 1970s preamps could not have been quieter than today's? Sm7 is also now commonly called a quiet mic, yet for decades has been connected to technically inferior than today's gear in broadcast and film? If something was boomable, as sm7s often were, how come we didn't get piles of hiss? If today's superior preamps need improving to use them, something suggests that modern preamps get their superior performance by having lower gain than the old ones?

Yay verily! I have some answers Rob but they are a bit technical so many here had better fortify themselves with THREE Weetabix (or just go and read the Beano for a bit).

"Oil be bek!"

Dave.
 
Phew! This is quite a convoluted story, garnering is as it does "expectations" bandwidths and psycho-acoustics. But let us, in the words of the song from that gagging movie, "Start at the very beginning"?

The mic input on the Ferrograph recorder. ASAICT Rob the Series 4 had an input traff and although I cannot find a ratio specc' for it I suspect it was like the "Wearite" accessory transformer, about 1:16? That is a noise free gain boost of 24dB! The input sensitivity (for "full" tape flux as they put it) was 3mV or -48dBu or -50dBV so a 57 at -58dBV should have easily given meter reading around -6 to -8dB below peak recoding level.

The signal to noise ratio of the S4 was -50dB (ref 3%thd?) so the noise contributions of the mic amp and tape were about comparable and that is with a pretty "domestic" mic pre using a PENTODE! In the pro audio and film world triode pre amps using DC heating (built one) and really expensive input transformers could easily be made that were 12dB more sensitive than the Ferro's and 10dB or better for noise.
The historical fact is that transformerless solid state pre amps could not compete for noise with traffs and triodes until very recently and most still have way worse headroom!

"Expectations". Peeps listen to CD and even the better MP3 stuff and then find they cannot get the same results with gear costing 1/10,000th the money. But in fact if they were to learn a bit more and possible be more selective in their purchases they COULD get very good results from a modest setup....

HOW many time have "we" had to tell noobs NOT to slam everything to 0dBFS! If you crank the system to get those levels you WILL bring up noise from pre amps which are, as I have shown above, little better than the Ferrograph S4's, if as good!

Lots more to say but I shall stop now and (IF anyone is still there!) deal with individual points?

Rob. Your Ferri' and mic seemed to be the Hi Z combination? Typically HZ mics were "50kOhms" so assuming a 150 Ohm capsule (they are not but we cannot know) that is a boost of 25dB and puts easily enough juice into that Pentode's grid. Note to that such mics were regularly plugged into guitar amps? We never had "noise" problem except when the landlord of the pub shouted "turn that fekker down!"
 
Thanks for all the answers! I also think that these mics just require more gain, although thanks to my newbism I was not sure if it's normal. Also, i checked the specs of 2i2 -gain range is -4dB to +46dB which, as I understand, is not very much. Based on your answers I understand that an external mic pre with at least 60dB of gain would be more suitable (TBH 2i2 is also fine for me given that even when using 80%-85% of the gain range the signal is clear).
 
Not quite - it was a Series 7 a 722HD, and the mic inputs were 600 Ohm (from memory, and was a good match to the new fangled SM57. I just don't remember noise ever really being a problem.
 
Not quite - it was a Series 7 a 722HD, and the mic inputs were 600 Ohm (from memory, and was a good match to the new fangled SM57. I just don't remember noise ever really being a problem.

Yes, IIRC the mic pre on the 7 was the very common DC coupled pair of low noise Silicon transistors. This could give a decent noise performance when applied to tape. I have similar inputs on my Teac A3440 and son got very acceptable results with various cheapo dynamics....For tape!

Trouble is, these days interfaces have a basic noise floor better than -100dBFS (and if yours doesn't Mr Newb you have bought a crock!) and such a pre amp would look pretty bad.

Expectations again!

Dave.
 
:facepalm: lol ok, ok, let's calm down. everything's ok.

I am perfectly calm. I have also had a guy with a hum problem on another forum where it turned out his amplifier definitely was NOT earthed!

There use to be something of an epidemic of singers and guitarists getting electrocuted. In this country at least that is now very, very rare due in part to the widespread use of RCDs*. The rise and rise of home recording could see the figures rising again.

"Ignorance" is certainly NOT "bliss" when it comes to electricity.

*And, if you don't know what one of those is FEKKING WELL find out!

Dave.
 
Rob, some data!
Sorry you have to suffer my croaking. I no longer have an SM57, gave it to son. The mic is a Prodipe TT1 with big foam gag on it and I am brushing it with lips. The Teac A3440 was hitting 0vu and bit over. Mic into unbalanced recorder input via adaptor (picks up hum a treat!) .

The tape is Ampex 406 and the machine was not lined up for it (Mr Beats might know how far out it might be?) but replay was a dB or two hotter than record on the meter so I might need a bit higher bias?

Before the tape moves the replay amp noise is -56dBu and the tape noise makes that worse to -50dB. About right for a non-optimized f-off tape recorder of its vintage?

That recording was then fed to line in 3 of my NI KA6 and peaked to -12dBFS. Tape noise was -51dBFS and, big thump, "OFF" noise dropped to -63dBFS and is mainly 50Hz hum from the 4mtr unbalanced lead draped across the room.

My conclusion is, the setup makes acceptable recoding but nothing really good enough in this digital world?

Dave.
 

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I'm not sure on that Dave - in this digital age, so few actually use anything like the range available, the old 'good' specs still hold up. In fact, the only real need for expanded good noise performance is in stripped down music with maybe a voice and an acoustic guitar where the range goes pppp to ffff, which is a rare song. So much music now is busy 100% of the time, so unless we're talking about a piece recorded in a cathedral with a two hundred voice choir and organ that starts with one solo singer singing very quietly - the noise floor isn't an issue - is it?
 
I'm not sure on that Dave - in this digital age, so few actually use anything like the range available, the old 'good' specs still hold up. In fact, the only real need for expanded good noise performance is in stripped down music with maybe a voice and an acoustic guitar where the range goes pppp to ffff, which is a rare song. So much music now is busy 100% of the time, so unless we're talking about a piece recorded in a cathedral with a two hundred voice choir and organ that starts with one solo singer singing very quietly - the noise floor isn't an issue - is it?

Yes. And no! "Expectation" Again, the newb bangs a '57 into a ~$100 interface and sees a pretty feeble reading on the meter for say 50% gain advance. They then crank the gain and wonder why the noise id bad RELATIVE to a "No Signal Condition" but as you say, 99% of the time is does not matter because the environment will be "noisier" than the electronics.

This is the condition we find with tape, no matter how good the mic amp, tape (and my test has shown even replay amp) noise dominates. Give a guy with an 80-8 a Grace M102 and he is STILL no better off! Even with Dolby. (yes, I know DBX gives a higher DRange but it was never liked over here because of the side effects. Ok for "pop" I guess)

The most demanding recording situation is Voice Overs (for noise that is) but even here a decent capacitor mic and most AIs of the F'rite camp or my KA6 are good enough. Borderline perhaps with a 7b but even there a Home Bod is unlikely to have a quiet enough place for the electronics to matter?

Most of my 50 odd years of audio experience were in LISTENING to records, cassettes and FM stereo and most of that to small forces and classical music. Even the very best sources were only just tolerable. I can still remember my very first CD experience. Quad 405 driving some Big M Castle Acoustics. Bat out of Hell. From a silky, silent background came this fabulous, crystal clear sound! From then on it was ***k vinyl!

GOTS to get me one of these!

Dave.
 
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