sE ICIS tube swap

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sE ICIS tube swap

Postby Malcolm Boyce » Tue May 01, 2012 10:37 pm

So, I've been meaning for a while to change the tube in this mic and I finally just got around to doing it. Not being the first owner there is no way for me to be able to judge if the thing was still performing like new, which I guess is a good question for Al... Would a tube of this kind go "bad" in a relatively new microphone with reasonable use and care? Anyway, not to get too sidetracked...

The tube I removed is the original sE badged ECC83A and replaced it with Al's suggestion of a Ruby 12AX7AC5 HG+. The original configuration was always satisfying as a colour microphone, specifically for voice, but definitely suffered from a fairly substantial noise floor. I was curious, being not super familiar with the ins and outs of tube qualities in a setting of this kind, what I might find simply trying a replacement.

I haven't had a chance to do much with this new tube installed, but immediately noticeable is the substantially lower noise floor, which is something I was hoping for from a bare minimum standpoint. With a little bit of voice work, the extreme top end seems to be more open, with a dip in the upper mids seeming more pronounced with this new tube. More time with different voices will definitely help me asses if the overall sound is more complementary to what i am looking for, but just being that much quieter, with nothing else as a drawback, is enough for this to be a winning combination.

I will keep you all posted as to what I find as I go along with this.
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Re: sE ICIS tube swap

Postby Mathieu Benoit » Wed May 02, 2012 9:37 am

We had (still have I guess) an Apex 460 tube microphone. At first it was not a very good mic, it was fine for my demo purposes but my ear wasn't really developed back then and I wasn't recording anything mission critical anyways. The noise floor wasn't something I could really notice back then since again I was still pretty green. When Alain replaced the stock tube with some super expensive telefunken tube the noise floor dropped significantly. The 460 is very mod friendly too and at some point Alain was going to rebuild the whole thing but then we got the the Lawson and the 460 hasn't left that shelf ever since.
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Re: sE ICIS tube swap

Postby Alain Benoit » Wed May 02, 2012 11:50 am

Glad that you finally got around to doing that Malcolm, I know you've been talking about it for a while.
The noise floor difference does not surprise me neither does the apparent HF extension.
The upper mid dip I have not noticed in any other circuitry, it may just be the tube letting you hear that particular microphone's tailoring more easily.
As far as a tube aging with any kind of haste, that really depends on the support circuitry that the tube is a part of, if it's a good design it really should not age very fast at all.
The ICIS I did not really like when we tried it here but that was with the original tube, it seemed if I remember, to have a shrillness to it that was quite displeasing.

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Mathieu Benoit wrote:We had (still have I guess) an Apex 460 tube microphone. At first it was not a very good mic, it was fine for my demo purposes but my ear wasn't really developed back then and I wasn't recording anything mission critical anyways. The noise floor wasn't something I could really notice back then since again I was still pretty green. When Alain replaced the stock tube with some super expensive telefunken tube the noise floor dropped significantly. The 460 is very mod friendly too and at some point Alain was going to rebuild the whole thing but then we got the the Lawson and the 460 hasn't left that shelf ever since.


I may still someday replace the diaphragm in it.

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Re: sE ICIS tube swap

Postby Malcolm Boyce » Thu May 10, 2012 12:08 am

Alain Benoit wrote:...The upper mid dip I have not noticed in any other circuitry, it may just be the tube letting you hear that particular microphone's tailoring more easily.

.....The ICIS I did not really like when we tried it here but that was with the original tube, it seemed if I remember, to have a shrillness to it that was quite displeasing.
The lack of forwardness in the upper mids is a character that I hear in this mic and it just seems more obvious with this new tube. In comparison, If feels like there's a smearing of the HF content with the original valve.

The "shrillness" would certainly be an issue with the wrong kind of source. There is a HF rise that would be nasty in a lot of cases, but with the right voice it's a very nice combination.
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Re: sE ICIS tube swap

Postby Alain Benoit » Thu May 10, 2012 12:12 am

If I remember correctly the source was a male competition choral singer.

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