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I like the RCA 408a gold pin and quiet Jan Phillips 6028 .
The Pillip/Jan tubes are clear at the top where the rca is a bit thicker .
  The  GE tubes Ive tried were similar to the rca .
every WE tube Ive tried is too noisy .

 
wolcott said:
I like the RCA 408a gold pin and quiet Jan Phillips 6028 .
The Pillip/Jan tubes are clear at the top where the rca is a bit thicker .
  The  GE tubes Ive tried were similar to the rca .
every WE tube Ive tried is too noisy .
Click to expand...

Yes I bet they are! I like most RCA NOS product, but man they are hard to find these days. I had one pair of the GE branded tubes that had gold pins too but darned if I can remember where I got them, and I can find no reference to what appear to be a premium version anywhere. Unless the GE 5 Star catalog I have is just too old?  Those GE's sound awesome and quiet, they are in my MK-U47 build.

Its sad that as far as I can tell the WE tubes out there are just all not up to the task. Even the pairs I have found that make the initial burn in cut have started to show sonic artifacts down the road and have had to be replaced. I had one pair that sounded great but only lasted 6 months. The JAN Philips are easier to find a working set up to the task but I don't like the sound and they are still rather noisy IMO

Please everyone keep in mind here this is just one person testing their tube stock from multiple sources. No knock on the tube vendors out there but a lot of the tubes in the NOS market may have already not made the cut elsewhere. For example the only other place that I know the 408a tube is used is in the HiFi world for dedicated headphone amps.

EDIT: I have finally had some consistent luck with the WE Tubes. It seems that the USA large logo tube usually is fine but the European small logo tends to be not of the same quality and are far noisier.
 
Whatever happened to the MK47 PSU kit in the offing with the voltmeter?...Looked so promising but it's not in the 939Store yet...

Did I miss something or is this a dead thred?

Thx,

Mike
 
I just put together the Zayance Power Supply. Should the B+ be adjusted to 105vdc while in omni or cardoid? I notice there's a difference of about 6vdc depending on the position of the pattern switch.

Thanks  :)
 
OK, I get it. When using the 2.4K dummy load to set the voltage to 105, the relay on the mic is out of circuit when switched to pattern, so it reads an extra 6v. Once you plug the mic in, the voltage reads the same in both pattern switch positions.

I used the Beesneez K7 capsule in this build. No problems other than the capsule holder came with a stripped thread. For now, I've got it mounted with a single screw.

The mic is quiet and sounds great in cardioid . I'm not liking the omni yet, but I suspect that will change when using a different pre and experimenting with mic positioning.  (Edit: This is through a Groove Tubes brick, which is nowhere near my favorite vocal mic pre. I'll try it through some other pres later today as I have a session with a male rock singer that I suspect this mic will sound really good on. )

I'm considering ordering the Thiersch blue line in order to do a comparison. Has anyone compared it to the Beesneez K7 yet?
 
Hey dudes, I mounted my capsule and tested out my mk47 tonight and there were some issues. I stuck it in front of my acoustic and it was pretty noisy. Like constantly fuzzy. There's signal coming through and it sounded good, but if I hit my acoustic slightly hard it would distort in a funny way and the bass would wash everything out and sound kind of feedbacky. Anyone have an idea of what might be going on? I appreciate any suggestions. Thanks!
 
Timh said:
Hey dudes, I mounted my capsule and tested out my mk47 tonight and there were some issues. I stuck it in front of my acoustic and it was pretty noisy. Like constantly fuzzy. There's signal coming through and it sounded good, but if I hit my acoustic slightly hard it would distort in a funny way and the bass would wash everything out and sound kind of feedbacky. Anyone have an idea of what might be going on? I appreciate any suggestions. Thanks!
Click to expand...

What is the capsule you are using? The symptoms you are describing could be the capsule or the capsule connections and or something with the tubes. Does this situation vary with pattern selected? Have you tried other tubes? Make sure your High Impedance section is clean of flux. Have you tried breathing on the capsule like you would fog your glasses to clean them, I know this sounds funny but it is a really good test to see if your capsule is compromised.
 
Pip said:
What is the capsule you are using? The symptoms you are describing could be the capsule or the capsule connections and or something with the tubes. Does this situation vary with pattern selected? Have you tried other tubes? Make sure your High Impedance section is clean of flux. Have you tried breathing on the capsule like you would fog your glasses to clean them, I know this sounds funny but it is a really good test to see if your capsule is compromised.
Click to expand...

Good to know. The capsule is the Eric Heiserman HK47. It's probably the way I installed the capsule. It's my first mic build and I didn't really know what I was doing. I'll have to take some pictures today and maybe it'll be obvious to you where I went wrong.

New question: Must I solder the wires from the capsule to the leads on the bottom of the glass tubes? I soldered the wires from the capsule to the leads before they enter the glass tubes.
 
A quick performance update on my MK47.  The WE 408a tubes worked well for almost 2 years but the noise floor crept to the point of being unbearable. Today I installed a pair of GE 408a tubes and the noise floor is now way-way down, about the same as my Shure SM7b. After burn in I should be able to use mic again!

Now I'm just waiting for updates on Max's PVC M7 capsule. Could be an alternative to my current Beezneez M7.
 

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Hi,

i build a second 47 microphone. for the psu i search the triad choke, but I can not find it....sold out everywhere here in europe.
but i've find  a Hammond 157H Choke can i use this as alternative? almost the same values, until dc-resistance triad have 500 ohms, hammond have 408 ohms, is this a problem?

thanks
 
Hi Folks,

I fired up my MK47 for the first time the other night with a chinese k67 just to be safe.  I sounded great, i left the tubes to burn in for 24 hours or so and the mic was performing brilliantly, quiet, larger than life with HUGE low end, Loved it.

Having installed my BeesNeez M7 the mic is much noise floor is much higher.  Should I expect less output from an M7?
 
burglar said:
Hi Folks,

I fired up my MK47 for the first time the other night with a chinese k67 just to be safe.  I sounded great, i left the tubes to burn in for 24 hours or so and the mic was performing brilliantly, quiet, larger than life with HUGE low end, Loved it.

Having installed my BeesNeez M7 the mic is much noise floor is much higher.  Should I expect less output from an M7?
Click to expand...

Re soldered the capsule connections and cleaned the hi z section and the mic is super quiet now.  Very pleased.  There is however, less low end than i was expecting in this mic.  It sounds great but I'm wondering if I can get it slightly thicker by swapping the Jan Philips tubes?

Will I get this from GE's?  Which WE 408a's should I look at for good noise performance as I've read that some are better than others?
 
burglar said:
Re soldered the capsule connections and cleaned the hi z section and the mic is super quiet now.  Very pleased.  There is however, less low end than i was expecting in this mic.  It sounds great but I'm wondering if I can get it slightly thicker by swapping the Jan Philips tubes?

Will I get this from GE's?  Which WE 408a's should I look at for good noise performance as I've read that some are better than others?
Click to expand...

Probably not. Using same tube type from  different manufacturer shouldn't change low end response.
There were statements over the web, that u47 with 408a have less low end than with VF14.
First what you could check is the plate voltage after 100k resistor. In original unit it should be circa 34V.
Output capacitor at least 1uF, grid resistor 100M or higher.
 
What differences are people experiencing with WE, GE or RCA tubes as opposed to Jan Philips?
 
burglar said:
burglar said:
Hi Folks,

I fired up my MK47 for the first time the other night with a chinese k67 just to be safe.  I sounded great, i left the tubes to burn in for 24 hours or so and the mic was performing brilliantly, quiet, larger than life with HUGE low end, Loved it.

Having installed my BeesNeez M7 the mic is much noise floor is much higher.  Should I expect less output from an M7?
Click to expand...

Re soldered the capsule connections and cleaned the hi z section and the mic is super quiet now.  Very pleased.  There is however, less low end than i was expecting in this mic.  It sounds great but I'm wondering if I can get it slightly thicker by swapping the Jan Philips tubes?

Will I get this from GE's?  Which WE 408a's should I look at for good noise performance as I've read that some are better than others?
Click to expand...
They all sound different and the Phillips are reportedly some of the brighter/thinner sounding options.  As far as noise goes, 408a/6028 in general are just not great in terms of noise and one must make an effort in order to find pieces that are quiet enough for a mic.  I haven't gathered that there is any specific type of WE that is better than others though I've had a number of people tell me that they've had better luck with WE in general than with other brands.  Others have not.  I've had WE batches where people reported nearly every tube being usable, with others it was as low as 50%.  They production date/style had nothing to do with the success rate.  It's going to vary from tube to tube and there's no easy route here, unfortunately. 
 
Thanks for your input there Bowie.  I have x10 Jan Philips and the first pair are performing incredibly well with regard to noise.  I can barely find the noise floor.  Whilst the top end is very smooth and flattering, I do feel there could be a little more low end but i've only recorded my spoken word.  Do you have any 408a other than philips currently?
 
burglar said:
Thanks for your input there Bowie.  I have x10 Jan Philips and the first pair are performing incredibly well with regard to noise.  I can barely find the noise floor.  Whilst the top end is very smooth and flattering, I do feel there could be a little more low end but i've only recorded my spoken word.  Do you have any 408a other than philips currently?
Click to expand...
Hi, I have never had the Phillips and I try to avoid carrying 6028/408a's in general but I'll occasionally pick up a batch of the WE because they have garnered the most positive feedback.  It makes sense as WE was highly respected as a tube builder.  Everyone will have different experiences.  I've spoken with a few dozen MK47 builders and the most common email I get is requesting an alternative to the Phillips 6028 because nearly every one they tried was noisy/microphonic.  As your experience testifies though, everyone will have a different experience.  A friend of mine made a strong effort to find a specific brand that was better than the others but his conclusion ended up being that they are all noisy, with some being more tolerable than others.  I haven't screened thousands of these like I have with 12A_7s and 6072s so I am only able to pass along info from people who have shared their 408a/6028 experiences with me.  These threads will help but just remember that people are having vastly different experiences with these tubes so there is no one solution.  Just keep trying and you should land some good ones that satisfy both tone and noise requirements.  Fortunately, they're not expensive tubes.
 

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