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Rode NTK tube & warming-up tests
Old 24th November 2007
  #1
soulstudios
Guest
Wink Rode NTK tube & warming-up tests

Thought about posting this in low end theory, frankly what people consider low end here, makes me cackle with glee! Give me a four track and a $30 mic- that's low end.

Seeing as how there's always this debate about ntk's and their quality (or lack thereof), and the effects of the tube replacements therein, and warmup times.
I thought I would conduct my own small unreliable test in the matter and see the results for myself.
Set up:
I have two Rode NTK's, 20 digits apart on the production line (**014 & **034 respectively), both with different tubes.
Rode Tube 1 is a no-name affair, with a diamond 'j' on the bottom and 95-4 on the side (clues anyone?).
Rode Tube 2 is a russian military-grade 6h23N-EB (basically a more rugged sovtek).

I set them up in the following configuration, along with a shure sm58 as a control group.

rode tube 1 <--1cm--> shure <--1cm--> rode tube 2,
with each mic facing directly forwards at head height.

Now, I think my stereo isn't really clean enough to be a good judge of character for the mics, so I took to singing into them
myself. The idea was to sing directly into the middle of the setup, recording all three at once -
that way, you can easily tell if there was any difference between the two rodes.

The second test (far less scientific) was to sing the same tune into the same configuration after an hour of warmup time -
as some of you know, most modern tube mics usually don't sound much different after a warm-up period, however the rode ntk's are
purported to buck this trend. I myself concur with this fact, though I'd never tried to properly test it.

The second test has obvious problems, the first and foremost of which being that the second performance will not be the same as
the first - voice may be better, worse, etc. The second problem is that room temperature can change and affect the sound.
This being gearslutz however- I would ask you to ignore the performance, and focus on the sound of the mike itself,
using the shure to determine any significant performance difference that would affect the overall sound (basically, as the control group).
Nobody here's an idiot (well, I speak for myself) - and I'll be the first to admit how flakey this test is.

Nevermind. Here's the process:

Test one: record two melodies singing.
Wait hour.
Test two: record same two melodies.
Take all recordings and resample & dither down from 24/96 to 16/44, mono.

Here's the recordings in flac format:

No warmup, tube 1, tune 1
No warmup, tube 2, tune 1
No warmup, shure, tune 1
No warmup, tube 1, tune 2
No warmup, tube 2, tune 2
No warmup, shure, tune 2
Warmup, tube 1, tune 1
Warmup, tube 2, tune 1
Warmup, shure, tune 1
Warmup, tube 1, tune 2
Warmup, tube 2, tune 2
Warmup, shure, tune 2

Obviously the warmup won't have any affect on the shure - it's the control.

My findings (by no means definitive): the second tube is much better, smoother, and less bright, or tinny. After a warmup time it loses the bright high end and sounds a bit more 'tube'-ey!
Depending on what I was recording I would either warmup or not warmup, but I would definitely choose the tube 2 for most things...
having said that, they still sound like Rode ntk's, and the shure points that out, obliquely!
Feel free to draw your own conclusions or do your own (preferably better) tests.

All recordings were made through a motu 896hd, using the onboard (flavourless yet clean) mic preamps.
Anybody wants to question my choice in equipment, please go somewhere else. There's a reason why it's
gearslutz and not gearsnobs Criticise the test all you like though-
Cheers,
[email protected]
Old 24th November 2007
  #2
Lives for gear
 

Hey thanks for the post. I owned an NTK and got rid of it, not because I did not like the sound, but because it had no head room. I ran my NTK through an Apogee Ensembles pre and had a female singer hit a high note and the mic sounded like crap. It was fine in her alto range but as soon as she went up the mic started to distort like crazy.
But I do love the sound of that mic when it is used on the right source I love it on acoustic guitars and bright voices in a not so high range. If I could find that sound with high head room I would be all over it. In your test did you notice any change in head room from tube to tube?
Thanks, Scott
Old 24th November 2007
  #3
SRS
Lives for gear
 
SRS's Avatar
 

I have 2 NTKs... I like them for some things. I use them for drum overheads often and not a problem with the SPL handling. They go up to (I think) 158 db SPL. You mighta had a tube or mic problem with the one that couldn't handle the female vox. Cannot imagine it distorting cause of SPL. Maybe she was forcing air into the mic at that pitch???

I have standard tubes in mine btw.
Old 24th November 2007
  #4
soulstudios
Guest
Quote:
Originally Posted by sctt_stone View Post
Hey thanks for the post. I owned an NTK and got rid of it, not because I did not like the sound, but because it had no head room. I ran my NTK through an Apogee Ensembles pre and had a female singer hit a high note and the mic sounded like crap. It was fine in her alto range but as soon as she went up the mic started to distort like crazy.
But I do love the sound of that mic when it is used on the right source I love it on acoustic guitars and bright voices in a not so high range. If I could find that sound with high head room I would be all over it. In your test did you notice any change in head room from tube to tube?
Thanks, Scott
Not as yet - the second test (post-warmup) sounds more dynamic and less 'in-yo-face' to me, but I don't recall either having problems with distortion-
I've got a reasonable range and in the past I've tried all sorts of levels of vocals (high falsetto to deep bass) without a hitch-
however, I'm no soprano- I can't test that high-
I will say that I've recorded very high violin into it without issue, though.
I would second that suggestion that you either had a faulty diaphragm, or more likely a tube with issues (microphonics maybe).
[email protected]
Old 25th November 2007
  #5
Gear Nut
 

Have you guys had any luck with swapping tubes? Most people report that it makes very little difference which makes me wonder how instrumental the tube circuit actually is.
Old 25th November 2007
  #6
soulstudios
Guest
Quote:
Originally Posted by dantheman65 View Post
Have you guys had any luck with swapping tubes? Most people report that it makes very little difference which makes me wonder how instrumental the tube circuit actually is.

Read the above test. Listening to the samples will tell you what you need to know.
Old 29th November 2007
  #7
Gear Addict
 
BluegrassDan's Avatar
I have the Rode K2.

I have done LOTS of tube swapping in it, and I've toured all over the country and Japan with the mic. Recorded a LOT.

Here's the deal with tubes:

Stock Russian tubes: Sound okay. Not very 3D. However, they are consistant

NOS tubes ---- this is the FUN part!....they really do change the attitude of this mic!!!.....

Mullard: (1960s gold pinned version) Sound DEEP, with a shimmer on the top end. AWESOME sound!

Amperex: (1960s USA and Holland versions) Basically sound LARGE. Big 3D effect. Tight transients and NICE sound!

Siemens or Telefunken: (1960s Germany) These are pretty neutral (not to be confused with dull). REALLY tight bass and extended top end. GREAT sound!



It really depends on the source as to what tube you should try. If you want an example, listen to clips from my latest live album. My vocal is through my K2 with a NOS 1960s Siemens E188CC tube! See if you like it: Welcome to DansMusicOnline - The Gospel Way, Daniel Boner
Old 30th November 2007
  #8
soulstudios
Guest
Quote:
Originally Posted by BluegrassDan View Post
I have the Rode K2.

I have done LOTS of tube swapping in it, and I've toured all over the country and Japan with the mic. Recorded a LOT.

Here's the deal with tubes:

Stock Russian tubes: Sound okay. Not very 3D. However, they are consistant

NOS tubes ---- this is the FUN part!....they really do change the attitude of this mic!!!.....

Mullard: (1960s gold pinned version) Sound DEEP, with a shimmer on the top end. AWESOME sound!

Amperex: (1960s USA and Holland versions) Basically sound LARGE. Big 3D effect. Tight transients and NICE sound!

Siemens or Telefunken: (1960s Germany) These are pretty neutral (not to be confused with dull). REALLY tight bass and extended top end. GREAT sound!

Thanks BluegrassDan, any idea what the Electro-Harmonix 6922 sounds like (Ijust ordered a pair)? Also, any clue as to what the diamond with a J in the middle signifies for the unknown tube in my setup?
Thanks,
[email protected]

Last edited by soulstudios; 30th November 2007 at 12:18 AM.. Reason: stuff
Old 30th November 2007
  #9
Gear Addict
 
BluegrassDan's Avatar
Hey Soul

Electro Harmonix is a Russian tube. As a matter of fact (from what I understand), Electro Harmonix provides tubes for other Russian brands - like Sovtek - which they relabel. These tubes are about like all Russian tubes. Their sound is not BAD - but it is also not very flattering or 3D, not very punchy, not tremedously warm, not really "airy". However, the good thing about them is that you can find them easily and for a cheap price. They are also quite consistant and I always keep a few lying around as spares.

If the two tubes you have in the K2 came from the factory stock, they are probably both some sort of rebranded Electro Harmonix tube.

HOWEVER - if you're talking about a diamond, stamped in the glass, in the bottom of the tube (between the pins), you might have a Telefunken. [follow THIS link: http://natubes.com/data/images/product/large_166.gif ]BEWARE...there are some Chinese tubes being made right now that are fake copies of Telefunken tubes.

A GREAT resource is 6DJ8 Tubes From Brent Jessee Recording . Brent Jesse is very knowledgable and will talk to you on the phone, answering your questions if you need. The more you read about tubes you'll find some cool tips. Example: Some late 60s Siemens E188CC tubes (will fit your NTK or K2) were relabeled as RCA for distribution. The ONLY difference is that the RCA can be found on Ebay for $45 and the Siemens for $145!!!

Tube swapping is REALLY fun. You can totally change the sound of the mic and learn a lot in the process!
Old 1st December 2007
  #10
Lives for gear
 
JoeyM's Avatar
BluegrassDan thanks a lot for the info - I registerd here just to reply.

I bought my K2 a year ago and it's the best mic I own. NOW I feel educated to get some NOS tubes (I'll start with Amperex as per your description).

Because it's likely the best mic I'll have for a long time, I've tried other ways to make sure the sound is the best possible, like switching popscreens. I have a Shure Popper Stopper with double screens and that was taking away from the sound - after trying every material around I settled on one of those horrible looking green 3M scrubbies, those rectangle cleaning pads, carefully stretched out a little. Ugly, yes, but all the highs seem unnafected yet it offers 95% Plosive protection compared to the Shure. To each his own you know.

My niece sings through it and the K2 even with stock tube is pretty incredible, takes EQ real nice.

Other than that, any thoughts on the "proper" warmup time for the K2?

Maybe I'm foolish but I've been just turning it on and waiting a minute, like I've been doing woth tube guitar amps my whole life.

Thanks again Dan! And if you're gospel then throw a prayer my way man!

Joey
Old 2nd December 2007
  #11
soulstudios
Guest
Quote:
Originally Posted by BluegrassDan View Post
Hey Soul

Electro Harmonix is a Russian tube. As a matter of fact (from what I understand), Electro Harmonix provides tubes for other Russian brands - like Sovtek - which they relabel. These tubes are about like all Russian tubes. Their sound is not BAD - but it is also not very flattering or 3D, not very punchy, not tremedously warm, not really "airy". However, the good thing about them is that you can find them easily and for a cheap price. They are also quite consistant and I always keep a few lying around as spares.

If the two tubes you have in the K2 came from the factory stock, they are probably both some sort of rebranded Electro Harmonix tube.

HOWEVER - if you're talking about a diamond, stamped in the glass, in the bottom of the tube (between the pins), you might have a Telefunken. [follow THIS link: http://natubes.com/data/images/product/large_166.gif ]BEWARE...there are some Chinese tubes being made right now that are fake copies of Telefunken tubes.

A GREAT resource is 6DJ8 Tubes From Brent Jessee Recording . Brent Jesse is very knowledgable and will talk to you on the phone, answering your questions if you need. The more you read about tubes you'll find some cool tips. Example: Some late 60s Siemens E188CC tubes (will fit your NTK or K2) were relabeled as RCA for distribution. The ONLY difference is that the RCA can be found on Ebay for $45 and the Siemens for $145!!!

Tube swapping is REALLY fun. You can totally change the sound of the mic and learn a lot in the process!

Personally I think it's possibly more about the combination of tube & mic, than it is about the tube itself. I don't think any monophonic mic sounds '3d', and really you want to pick the right tube to compensate for shortcomings in your mic 's design- I'm picking up a copy of EHG's on someone else's recommendations for this specific mic- I'll let you know how they go. Thanks for the info on the telefunken Dan - although that's the tube that sounds the worst - I haven't checked to see whether it's a chinese fake yet.
Cheers,
[email protected]
Old 2nd December 2007
  #12
Gear Nut
 

Anybody know a reputable online dealer for tubes? I'm keen to pick up a few different types and have a play. Preferably ones that ship internationally.
Old 2nd December 2007
  #13
soulstudios
Guest
Quote:
Originally Posted by dantheman65 View Post
Anybody know a reputable online dealer for tubes? I'm keen to pick up a few different types and have a play. Preferably ones that ship internationally.
Australian company: Electronic Valve and Tube Company is where I've gotten mine.
Ordered last week.
Old 4th December 2007
  #14
Gear Addict
 
BluegrassDan's Avatar
The descriptions above are based on comparison between the tubes themselves in many different types of audio gear. Although very subjective, there is an audible difference between a Mullard 6922 tube and a Telefunken - the Mullard a deeper "colored" tube, and the Telefunken more neutral. If the tube you have is indeed a Telefunken, then it makes sence that you would observe the Russian tube to have less highs. Telefunken tubes (as I mentioned earlier) have extended top end.

But there is no tube that is "better". It's all a matter of taste and flavor. If "X" person is singing, what will help capture their voice accurately and put their vocal in the right area of the mix? Perhaps putting an Amperex tube in an NTK or K2 is the thing. Perhaps using a Royer ribbon mic is the thing? Maybe a U87? Maybe a FET U47?

From my experience, changing from a $20 Russian tube to a $50-$150 NOS vintage tube (of any brand) has the ability to turn the K2/NTK into a mic comparable to mics in the $2,000+ range.

The 3D soundstage that I'm talking about is not a stereo "image" thing. It's like the sound you get from old tube pres, and Neves. Just a LARGE sound. Very dynamic and full of texture that is absent in cheaper gear.

If I'm recording, I let the tube warm up for at least an hour. If I'm doing a few sessions I'll leave it on for days at a time. A hot tube will have maximum potentional for electron flow. It may take 40 minutes or more to reach a constant temperature.
Old 4th December 2007
  #15
soulstudios
Guest
Quote:
Originally Posted by BluegrassDan View Post
But there is no tube that is "better". It's all a matter of taste and flavor. If "X" person is singing, what will help capture their voice accurately and put their vocal in the right area of the mix? Perhaps putting an Amperex tube in an NTK or K2 is the thing. Perhaps using a Royer ribbon mic is the thing? Maybe a U87? Maybe a FET U47?
... thanks for the recording 101. Duh.


Quote:
Originally Posted by BluegrassDan View Post
The 3D soundstage that I'm talking about is not a stereo "image" thing. It's like the sound you get from old tube pres, and Neves. Just a LARGE sound. Very dynamic and full of texture that is absent in cheaper gear.
I wish people would describe things in terms of actual audio terminology- like, 'timbre', 'dynamics' and 'detail'- okay, I get that. "large" = fairly subjective, useless term. "3D" - again. Not hassling you personally, a pet hate.


Quote:
Originally Posted by BluegrassDan View Post
If I'm recording, I let the tube warm up for at least an hour. If I'm doing a few sessions I'll leave it on for days at a time. A hot tube will have maximum potentional for electron flow. It may take 40 minutes or more to reach a constant temperature.
As I understand it, most modern tube mics do not exhibit much if any difference after warmup - the NTK (can't speak for the K2) bucks this trend a little, but not by much, as can be heard. From my experience, about half an hour is adequate.
Onto the next test.
Cheers-
[email protected]
Old 6th December 2007
  #16
Gear Addict
 
BluegrassDan's Avatar
Soul,

I wonder if the warmup time is more directly related to the tube, rather than the "modern" mic itself.

I noticed while comparing tubes a while back that different tubes warm up differently - particulalry their early warm up. One that I remember would start to make sound about 10 seconds after turning it on, then after about a minute I would hear a sizzle and the gain would increase by probably 10db.

The current tube I'm using won't even start to make sound until about 40 seconds after turning it on. Then slowly the sound changes for another few minutes.
Old 6th December 2007
  #17
soulstudios
Guest
Quote:
Originally Posted by BluegrassDan View Post
Soul,

I wonder if the warmup time is more directly related to the tube, rather than the "modern" mic itself.

I noticed while comparing tubes a while back that different tubes warm up differently - particulalry their early warm up. One that I remember would start to make sound about 10 seconds after turning it on, then after about a minute I would hear a sizzle and the gain would increase by probably 10db.

The current tube I'm using won't even start to make sound until about 40 seconds after turning it on. Then slowly the sound changes for another few minutes.

You may very well be right - but then, it still comes down to what tube modern mic manufacturers select for their product - and this is influenced by the fact (I imagine) that they're going to get both reviewers and amateur musicians who are just going to plug the thing in and expect it to deliver it's best sound after one or two minutes.
It's my feeling that their selection of tubes would tend towards the ones which colour the least over time.
Cheers,
[email protected]
Old 8th December 2007
  #18
Lives for gear
 
JoeyM's Avatar
Are we in agreement the K2's tube is an impedance converter and not a gain stage?

If I didn't also buy an NT2a I'd never grasp how exact those mics sound, the K2 and NT2a. At least with female vocals in my case.

My neice did two takes of Cheryl Crow's Always on Your Side and every syllable we either destructively cut out the less nice ones, or if the vocals were both good I left them in for doubling.

Recorded through an RME Fireface 800 and into Nuendo @ 88.2 khz -

I can not for the life of me tell a difference in the K2 against the NT2a.

They both sound very nice and I'm glad I bought those two mics.

---edit update---
The room sound is warmer and rounder with a K2 than the coldness (useable and EQ-able coldness) with the NT2a, but lead vocals in a mix? I cannot find the least bit of difference.
Old 22nd January 2008
  #19
Lives for gear
 

Interesting test...thanks for doing this. I am also a bit motivated to try a different tube in my NTK. My NTK has actually been sitting in it's case without being recruited for duty for some time now. I just this past week pulled it out and tried recording some acoustic guitar with it for the first time. Set the mic up, got the sound piping into the monitors/cans and we were both, like, WOW!!...that sounds great! Perhaps it's just THIS guitar that's a great match (a nice old 60's Gibson SJ), but have heard that the NTK excels on acoustic guitar. Guess I won't be selling it now (as I had been considering). Coincidentally, the mic had been warming up for about an hour and a half or so.
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