Korby Kat replacement tube. Anyone?

[Bill@WelcomeHome]

I have a couple of Korby mics, and my 251 sounds like a 251... I auditioned them side by side. Have you spoken to Tracy about this? I would not assume that it was a tube issue without getting his opinion, and (at least when I was dealing with him) he takes pride in his products.

That said, since replacing tubes makes such a big difference in things like guitar amps, why not try to change too a better tube to see what the effect is? The question becomes, what better tube?

[feck]

I put a NOS 67 Mullard in my KAT 4 and it really took the mic to another level. I definitely recommend experimenting with it.

[GYang]

NOS Telefunken did improvement for me, but it took me a while, before I've found it. Be patient in searching for NOS tubes.

[Aith]

Really interested in this one too

[hoop]

I replaced my Korby tube with a GE NOS 5 star - it was like getting a new mic.

The electro-harmonix that was in there is not a great tube.

[JVP]

So... I found a couple of NOS GE 5 star GL-6072's for my Korby's. I've had them in there for a couple of days now tracking a couple of different singers and acoustic guitars. The new tubes fix all of the issues I was having. What a difference! The harsh bite is gone. Now the mic has a sweeter, open high end. Lows are similar. The mid range is much fuller and more detailed. Vocals sit better in the mix without eq now. I'm a happy camper!

One thing that I was surprised by is that now, with the 6072 5 star installed, the mic has more headroom. It is quite a bit more dynamic. I noticed, especially on acoustic guitar, that it can handle more spl before the tube starts to saturate. For me, that's a good thing.

I hope this helps anyone in the future. I was worried that I would spend the money on a NOS tube and there would only be a subtle difference. I can assure you that it's not subtle at all. It still sounds like the same mic. Just now, it has much better characteristics. Highly recommended!

[hoop]

Yes!!

I had forgotten that I put in 6072s. Not subtle.

Made the mic much more useable, from a headroom perspective.

[steins]

I replaced the Korby tube with a NOS 12AX7 Telefunken Diamond Bottom. It didn't made a huge difference, but it sounds a little bit sweeter in the top end. I'm not sure, but I have a feeling that the headroom has actually decreased. I have to test it again, it's been a while since I used it.

Actually, I'm about to send the Korby in for tuning. Has anyone of you done this? I'm not sure what kind of words I should use to describe what I want to be done.. 'Less hars and more sweetness' could mean different things to different people. After reading this thread, I think I will be trying a NOS GE 5 star GL-6072 first.

Stein Tore

[JVP]

I wouldn't send the mic in without trying the 6072 5 star first. I actually tried a Telefunken diamond bottom 12ax7 in the Korby as well. It was terrible. I bought the Telefunken for a different price of gear, but tried it in the Korby for fun. 12ax7's break up too quick. They belong in guitar amps not vocal mics! If you are hearing the same harsh, top end bite that I was hearing, the 6072 will fix it

[steins]

Originally Posted by JVP

I wouldn't send the mic in without trying the 6072 5 star first. I actually tried a Telefunken diamond bottom 12ax7 in the Korby as well. It was terrible. I bought the Telefunken for a different price of gear, but tried it in the Korby for fun. 12ax7's break up too quick. They belong in guitar amps not vocal mics! If you are hearing the same harsh, top end bite that I was hearing, the 6072 will fix it

Thanks! I will try that. It was actually a Korby KAT owner that recommended the NOS Telefunken 12ax7 to me, but you confirm what my ears are telling me. I've tried searching for a 6072, but there seems to be many variations, and I do not consider myself as a tube expert. Would one of these do:

https://www.tubeworld.com/6072.htm#6072ge

or this:

VINTAGE ANTIQUE GE 5 STAR 6072 RADIO STEREO AUDIO AMPLIFIER TUBES 12AY7 | eBay

Stein Tore

[JVP]

As long as its a NOS GE 6072 5 star, you will be fine. I don't know for sure but the GL-6072 (5 star), 6072 (5 star) and 6072a (5 star) are all pretty much the same tube. Someone please chime in if I'm wrong. At least, any of these tubes will kick ass in your Korby!!

The pair on eBay are the right ones but I think the price will get pretty high at the end of the auction.

[steins]

Originally Posted by JVP

As long as its a NOS GE 6072 5 star, you will be fine. I don't know for sure but the GL-6072 (5 star), 6072 (5 star) and 6072a (5 star) are all pretty much the same tube. Someone please chime in if I'm wrong. At least, any of these tubes will kick ass in your Korby!!

The pair on eBay are the right ones but I think the price will get pretty high at the end of the auction.

Thanks again, I didn't know the difference between the 6072 and the 6072A, but it seems the 6072A is required in some circuits that require tubes with controlled heater warmup. Otherwise, the tubes are the same. Time to pull out the credit card .

Stein Tore

[Bill@WelcomeHome]

Interesting. Mine, a very early model, has a JAN 5703wb. My Empyrean microphone (an early custom-built Korby based on a U-47) uses an Gold Areo 12ax... can't say that I ever heard of 'Gold Areo' but I'm not a follower of tube manufacturers.

[midnightsun]

Originally Posted by JVP

I have a pair of Korby Kat 251 mics. I have used them moderately over the last 4 years but am not too impressed by them overall compared to other mics I own. They seem to have a harsh breakup in the high end.

It seems that the tube is most likely the culprit. So my question is, is there any one out there that has swapped the stock Russian EH tube with something else and is noticed a significant improvement? I would like to get a pair of GE 5 star 6072's but it's an expensive experiment!

I would prefer not to sell these, but if the right tube can save the day...

Is your pair of mics matched? Do they sound identical? Try swooping capsules from one mic to the other. Does this make a difference. The nice thing about having a matched pair is that you can try different tubes and have an immediate comparison. My Korby KAT pair is matched along with my capsules. They are dead on. For stereo micing, Blumlein, XY, etc I have the best results with the 67 or the 12 because I can vary the polar patterns which adds tremendous flexibility. I realize that I am not responding directly to the tube issue rather I am addressing the point that you are less than satisfied with the sounds you are getting and are looking for reasons. Could it be that you have grown tired of a sound you once liked? Sometimes the enemy of good is "better".

[JVP]

I do have a matched pair of Korby 251's. When I bought my NOS GE 5 Star's, I only replaced one so I could compare. Like posted previously, I much prefer the GE tube over the EH stock tube.

As far as getting bored of it's sound, I was never really excited about the mic to begin with. I admit, I bought them based off of hype from people I trust. Perhaps they had better stock tubes in theirs. I found with mine, originally, that the vocals recorded through the "EH tubed" Korby's never sat right in the mix. Just a bit too much bite in the upper mids and low headroom. My belief is that with the right vocal mic, the vocal should sit in the track with no eq (until the mix anyway). I have all of the other flavors of vocal mics but needed something on the bright side hence the 251 capsule. I wanted a stereo pair for drum duties.

I have recorded several vocals with the new "GE tubed" Korby. When a singer needed a brighter sounding mic, the Korby is really coming through now. Especially on pop vocals. No more bite. It's smoother and more detailed sounding.

[Bill@WelcomeHome]

Originally Posted by JVP

I do have a matched pair of Korby 251's....I was never really excited about the mic to begin with. ....

Well, as I said before I was not trying to get a 'Korby', I was looking for an accurate 251 emulation, and I had a 251 beside the Korby to compare, which it did favorably. And mine did not come with an EH tube. I'm curious as to the choice to put EH tubes in a costly mic though... I take them out of guitar amps ASAP. (shrug.)

I was told by a designer friend of mine that he is surprised that the tube type (manufacturer) makes such a difference in a mic, because of how a tube is used in a mic. I did not press him for details, but he did assure me that an investment in an expensive tube would be offset by the life expectancy one would have for the tube as the tube is not employed as it would be in most other electronic gear. So at least those GEs should last many years!

[midnightsun]

Originally Posted by JVP

I do have a matched pair of Korby 251's. When I bought my NOS GE 5 Star's, I only replaced one so I could compare. Like posted previously, I much prefer the GE tube over the EH stock tube.

As far as getting bored of it's sound, I was never really excited about the mic to begin with. I admit, I bought them based off of hype from people I trust. Perhaps they had better stock tubes in theirs. I found with mine, originally, that the vocals recorded through the "EH tubed" Korby's never sat right in the mix. Just a bit too much bite in the upper mids and low headroom. My belief is that with the right vocal mic, the vocal should sit in the track with no eq (until the mix anyway). I have all of the other flavors of vocal mics but needed something on the bright side hence the 251 capsule. I wanted a stereo pair for drum duties.

I have recorded several vocals with the new "GE tubed" Korby. When a singer needed a brighter sounding mic, the Korby is really coming through now. Especially on pop vocals. No more bite. It's smoother and more detailed sounding.

I am glad that you are happier with the KAT 251 with the GE tube and that it is coming through. The investment that you have in the pair should delight you rather than be so so. For me the KAT 67 and KAT 12 are my first choice for drum overheads. For the most part I use the KAT 251 on some vocals.

[steins]

Originally Posted by JVP

As long as its a NOS GE 6072 5 star, you will be fine. I don't know for sure but the GL-6072 (5 star), 6072 (5 star) and 6072a (5 star) are all pretty much the same tube. Someone please chime in if I'm wrong. At least, any of these tubes will kick ass in your Korby!!

The pair on eBay are the right ones but I think the price will get pretty high at the end of the auction.

I finally got to try the NOS GE 6072A 5 star in my Korby, and I have to say the difference is huge. Harsness is gone, and the headroom is much improved. I recorded a female singer yesterday using the 251 head. The result was warm with a smooth top end, and without the previous harsness that had troubled me before when using either the stock tube or a Telefunken Diamond NOS.

Stein Tore

[kingsley]

I have tried the telefunken and a mullard 10m in my kat 4. The tele is about the top end .... maybe a little sharp on some vox. The mullard is about the rich mids.... still detailed but without the extended top end.....smoooth I have been enjoying the mullard lately. Maybe someday i will try the 5 star.

[BradD]

I just picked up a NOS GE JAN 6072a to try out in my Korby and then realized it does not say "5 star." Is this the right tube for the job, or do I need the 5 star? Thanks.

[popmann]

Last I heard, if you called The Mic Shop, his brother was working there and knows how to service the old mics they made.

[kidvybes]

Originally Posted by BradD

I just picked up a NOS GE JAN 6072a to try out in my Korby and then realized it does not say "5 star." Is this the right tube for the job, or do I need the 5 star? Thanks.

...the JAN (Joint Army Navy) is the military/industrial version of the same tube...you're good...

Sent from my SPH-M820 using Tapatalk

[BradD]

Excellent. Thanks.

[yztzzxga]

it was a tube issue without getting his opinion