|
Post by ChaseUTB on May 8, 2017 22:22:13 GMT -6
This is a huge bummer. Hope he can find the tubes, at least for mine. Haha Good luck man hope you get lucky and a great build... if you do go for this go for the Thiersch capsule ( I prefer blue line ) ( pvc membrane )
|
|
|
Post by Guitar on May 9, 2017 13:13:08 GMT -6
There must be some kind of poetic justice that a U47 clone has as many problems with tube sourcing as the aging originals. Some kind of haunted circuit.
|
|
|
Post by drbill on May 9, 2017 13:46:14 GMT -6
Tubes are weird. Especially in the 2000's. I believe the reality is that the tubes spec'd for these mics were never designed for audio circuits, and using them in audio circuits - especially mics - places undo demands on them. When guys like Dan and Scott have to go thru dozens and dozens of tubes to find workable ones - only to find out a couple weeks later that they crap out then...... If I knew how difficult it was going to be to get a workable MK47, I never would have bought one. I cross my fingers every time I use it now. The memories of lightning storms and ocean waves of noise haunt me.... Crackle, pop, swish, boom. It's not just a high noise floor - it was intermittent modulating noise. I wish Stam and all the buyers the BEST!!!
|
|
|
Post by svart on May 9, 2017 14:26:26 GMT -6
Wow, all you guys having issues with tubes.. I bought two tubes off Ebay, put them in the mic, and never had any issues with noise. I didn't even burn them in before doing a session. Quiet and lush. Use the mic all the time with no problems at all.
That being said, I did just wire the parts to a hacked up PCB without regard to layout or anything.
I tend to think that with so many having issues with tubes, that there might be an issue with the design that renders all but a few tubes noisy.. So what's the noise? White/hiss? Rushing?
|
|
|
Post by jeremygillespie on May 9, 2017 14:47:13 GMT -6
I've shot out the AMI build against two of our real 47's. Not even close. Not the same ballpark. The general idea is there, but in all honesty, not something I'd spend money on. Which capsule and output transformer did you use? I assume the K47 Classic capsule offered by AMI and the BV08? Thanks Full AMI U47 kit, with all components needed, BV8Classic transformer, K47Classic capsule, NOS Telefunken EF800 tube, 47TSA Noval tube socket, Binder connector, made in USA 47RP-PSU , Accusound AT7 made in the USA cable, 47Box, 47 shock mount.
|
|
|
Post by drbill on May 9, 2017 15:03:00 GMT -6
Not low level "hiss". Pops. Crackling, Rushing waves, Lightning storms. All kinda crap that fades in and out at random. Usually at the worst opportune moment. Low level "hiss" I could deal with, but not this stuff. Made the mic unusable - followed by beautiful lushness - followed by unuseable, etc.. I pretty sure the spec sheet on these mics says "not to be used in microphones". At least that what someone once told me.
|
|
|
Post by svart on May 9, 2017 15:24:04 GMT -6
Not low level "hiss". Pops. Crackling, Rushing waves, Lightning storms. All kinda crap that fades in and out at random. Usually at the worst opportune moment. Low level "hiss" I could deal with, but not this stuff. Made the mic unusable - followed by beautiful lushness - followed by unuseable, etc.. I pretty sure the spec sheet on these mics says "not to be used in microphones". At least that what someone once told me. That's a good starting place to determine what the problem is. That could be a few things. One of the biggest issues is leftover flux on the high impedance pins of the tubes, even down into the connectors as the flux/rosin runs down the lugs. That will certainly create crackles and pops. The grid stopper resistor should be low noise, so metal film. Also, being dirty with flux can cause noise here too. I cleaned everything (but the capsule) with acetone until there was no residue left on anything. Maybe this helped, I don't know. I also lightly sanded the pins on the tubes as they were slightly tarnished. I'll try a test. I'll buy some random cheap 408A/6028 tubes off ebay again and see what happens. If I get silence, I'll see if I can track down what might give me the noises you describe.
|
|
|
Post by drbill on May 9, 2017 16:15:01 GMT -6
Not low level "hiss". Pops. Crackling, Rushing waves, Lightning storms. All kinda crap that fades in and out at random. Usually at the worst opportune moment. Low level "hiss" I could deal with, but not this stuff. Made the mic unusable - followed by beautiful lushness - followed by unuseable, etc.. I pretty sure the spec sheet on these mics says "not to be used in microphones". At least that what someone once told me. That's a good starting place to determine what the problem is. That could be a few things. One of the biggest issues is leftover flux on the high impedance pins of the tubes, even down into the connectors as the flux/rosin runs down the lugs. That will certainly create crackles and pops. The grid stopper resistor should be low noise, so metal film. Also, being dirty with flux can cause noise here too. I cleaned everything (but the capsule) with acetone until there was no residue left on anything. Maybe this helped, I don't know. I also lightly sanded the pins on the tubes as they were slightly tarnished. I'll try a test. I'll buy some random cheap 408A/6028 tubes off ebay again and see what happens. If I get silence, I'll see if I can track down what might give me the noises you describe. Thanks, but no need. Dan D is a very experienced mic builder, and he went thru well over a hundred tubes to find suitable ones. He cleaned everything well, built well, etc.. The problem is in the tubes themselves as is evidenced by the number he had to sort through to get keepers - from Bowie and from other sources as well - multiple brands. And this was not only on my mic, but Scott Leibers, Dans pair and on several mics he built for others. I've got things working now (or should I say Dan got it working), and only hope it stays working, cause the tubes themselves tend to go wanky even after extensive testing and use for quite awhile. I've got some spares from England as well. Hopefully won't need to use em.
|
|
|
Post by rowmat on May 9, 2017 16:26:51 GMT -6
The Telefunken EF12 seems to be a commonly used alternative to the VF14 in U47 clones. Our Flea 47 uses an EF12 and sounds great. There seems to be several EF12's on eBay most of the time.
|
|
|
Post by indiehouse on May 9, 2017 17:16:23 GMT -6
Man, I had no idea this mic was so finicky. Giving me pause.
|
|
|
Post by sll on May 9, 2017 17:40:55 GMT -6
Not low level "hiss". Pops. Crackling, Rushing waves, Lightning storms. All kinda crap that fades in and out at random. Usually at the worst opportune moment. Low level "hiss" I could deal with, but not this stuff. Made the mic unusable - followed by beautiful lushness - followed by unuseable, etc.. I pretty sure the spec sheet on these mics says "not to be used in microphones". At least that what someone once told me. That's a good starting place to determine what the problem is. That could be a few things. One of the biggest issues is leftover flux on the high impedance pins of the tubes, even down into the connectors as the flux/rosin runs down the lugs. That will certainly create crackles and pops. The grid stopper resistor should be low noise, so metal film. Also, being dirty with flux can cause noise here too. I cleaned everything (but the capsule) with acetone until there was no residue left on anything. Maybe this helped, I don't know. I also lightly sanded the pins on the tubes as they were slightly tarnished. I'll try a test. I'll buy some random cheap 408A/6028 tubes off ebay again and see what happens. If I get silence, I'll see if I can track down what might give me the noises you describe. Did all that. Sanded pins with 1000 grit sandpaper, cleaned them with contact cleaner, alcohol, and carbo-sol. Cleaned all flux off PCB with carbo-sol. All resistors replaced with metal film. Finally found a pair of tubes that are quiet (no crackle and sputter). White noise level is a little high on them so this mic can't be used for a quiet acoustic source. If you found 2 good tubes right off the bat, you should buy a lottery ticket as well.
|
|
|
Post by svart on May 9, 2017 18:05:50 GMT -6
That's a good starting place to determine what the problem is. That could be a few things. One of the biggest issues is leftover flux on the high impedance pins of the tubes, even down into the connectors as the flux/rosin runs down the lugs. That will certainly create crackles and pops. The grid stopper resistor should be low noise, so metal film. Also, being dirty with flux can cause noise here too. I cleaned everything (but the capsule) with acetone until there was no residue left on anything. Maybe this helped, I don't know. I also lightly sanded the pins on the tubes as they were slightly tarnished. I'll try a test. I'll buy some random cheap 408A/6028 tubes off ebay again and see what happens. If I get silence, I'll see if I can track down what might give me the noises you describe. Did all that. Sanded pins with 1000 grit sandpaper, cleaned them with contact cleaner, alcohol, and carbo-sol. Cleaned all flux off PCB with carbo-sol. All resistors replaced with metal film. Finally found a pair of tubes that are quiet (no crackle and sputter). White noise level is a little high on them so this mic can't be used for a quiet acoustic source. If you found 2 good tubes right off the bat, you should buy a lottery ticket as well. I'm an engineer.. I don't believe in coincidence in electronics!
|
|
|
Post by drbill on May 9, 2017 18:12:12 GMT -6
As they say in the studio trenches, **** - I mean "coincidence" - happens. When you've got two guys as good as Scott and Dan, believe it. In studios I've encountered things that defy belief or description. Do you believe in voodoo???
|
|
|
Post by sll on May 9, 2017 18:22:50 GMT -6
Did all that. Sanded pins with 1000 grit sandpaper, cleaned them with contact cleaner, alcohol, and carbo-sol. Cleaned all flux off PCB with carbo-sol. All resistors replaced with metal film. Finally found a pair of tubes that are quiet (no crackle and sputter). White noise level is a little high on them so this mic can't be used for a quiet acoustic source. If you found 2 good tubes right off the bat, you should buy a lottery ticket as well. I'm an engineer.. I don't believe in coincidence in electronics! There's no coincidence. The tubes are not suitable for microphones.
|
|
|
Post by wiz on May 9, 2017 18:26:32 GMT -6
I would love it if you could do some investigating svart I will even kick in for the tubes cheers Wiz
|
|
|
Post by kcatthedog on May 9, 2017 18:30:52 GMT -6
Not second guessing any of the statements here but there are lots of people around the world using this 2 tube design in 47 mikes. I have read that people worked hard to get good tubes but I don't often read that people are not using their mikes due to the tubes ?
Are you saying there is something inherently wrong with the 408 tube design: its quiescence ?
|
|
|
Post by svart on May 9, 2017 18:36:27 GMT -6
I'm an engineer.. I don't believe in coincidence in electronics! There's no coincidence. The tubes are not suitable for microphones. The two in my mic beg to differ!
|
|
ericn
Temp
Balance Engineer
Posts: 14,934
|
Post by ericn on May 9, 2017 18:48:00 GMT -6
There's no coincidence. The tubes are not suitable for microphones. The two in my mic beg to differ! No but as an engineer you have to understand that your personal experience counts as a sample of 1 and the total insigncance of 1 ! Now I'm also sure a fair number who have built it are more tolerable to noise than Dan Scott and Bill! I also wonder if Oliver / TAB had a stock of good tubes!
|
|
|
Post by svart on May 9, 2017 18:52:56 GMT -6
I would love it if you could do some investigating svart I will even kick in for the tubes cheers Wiz Ok. I bought another WE408A set on Ebay. We'll soon see!
|
|
|
Post by dandeurloo on May 9, 2017 19:35:09 GMT -6
I'm an engineer.. I don't believe in coincidence in electronics! There's no coincidence. The tubes are not suitable for microphones. The tube data sheet even says that. But no one seems to read those. Haha
|
|
ericn
Temp
Balance Engineer
Posts: 14,934
|
Post by ericn on May 9, 2017 19:39:51 GMT -6
There's no coincidence. The tubes are not suitable for microphones. The tube data sheet even says that. But no one seems to read those. Haha You expect people to read?
|
|
|
Post by svart on May 9, 2017 19:44:31 GMT -6
There's no coincidence. The tubes are not suitable for microphones. The tube data sheet even says that. But no one seems to read those. Haha Do you always do what you're told? Lol.
|
|
|
Post by drbill on May 9, 2017 19:44:41 GMT -6
"The tube data sheet even says that. But no one seems to read those. Haha" ^^^^ Quoted for reality. Bottom line - they CAN work. My mic works great. Now. But only because of DAN!, and probably Scott too, as I know they went through the trials and tribulations together - and only because of dogged persistence in getting a pair of tubes that work well and in tracking down and redesigning parts of the build.
|
|
|
Post by svart on May 9, 2017 19:49:46 GMT -6
There's no coincidence. The tubes are not suitable for microphones. The tube data sheet even says that. But no one seems to read those. Haha Data sheet explicitly says that it is suitable if (filament) microphonics is not a concern. www.westernelectric.com/spec_sheets/408A.pdfFirst page, last sentence in the Description section. Guess nobody reads those, indeed.
|
|
|
Post by dandeurloo on May 9, 2017 19:58:48 GMT -6
The two in my mic beg to differ! Now I'm also sure a fair number who have built it are more tolerable to noise than Dan Scott and Bill! I wonder about this as well. Compared to any vintage tube mic I've used or my other clones, the noise floor is still much higher even with the lower noise tubes I've found. If I was recording drums or a rock band it wouldn't really matter. But on a vocal in a acoustic track the noise floor of the tubes is to high to use. Since the last few records I've done have been mostly acoustic music these mics haven't been used at all.
|
|