ericn
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Balance Engineer
Posts: 14,934
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Post by ericn on May 14, 2017 14:50:46 GMT -6
Is it not about time for an admin to split this thread into two? nah to much fun ! Chris can come off like a dick, but he knows his shit as well as Dan & Scott ! If you get to know him in person you realize he just comes across a little hard in print, and who else has stories of Sewer Robots! As JK said , sometimes there are no absolutes in this we can get along and disagree, if we can't we're screwed in more than just tubes!
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Post by wiz on May 14, 2017 17:23:27 GMT -6
I think everyone cut everyone some slack, and respect.. technical and otherwise.
Pretty good chance here to get to the bottom of something that seems to have plagued a lot of people...why the 408a is not performing well in every mic.
So, lets amicably follow the path... anyone got a noisy pair of tubes ? send em to Cris, let him send you the ones he just tried... then we can see where the issue is...
Wouldnt that be a wonderful outcome?
cheers
Wiz
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Post by kcatthedog on May 14, 2017 18:21:14 GMT -6
svartI have max's mk-u47 build and the original tubes that it comes with. I found they never got quiet so didn't use them. How about I send them ? If I am understanding your comments above correctly ? My build is stock with the Thiersch blue cap. thx.
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Post by sll on May 14, 2017 18:53:18 GMT -6
It would be great if svart found something that myself and others have missed. It still does not explain why I had to go through 50-60 tubes to find a few pairs that were useable. If something was wrong with my build, no pairs of tubes would end up being quiet. Meaning the problem would follow the mic regardless of what was put into it.
I do find some of the tone of this thread to be reminiscent of GS. Makes me feel like I should take a break from this forum.
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Post by Guitar on May 14, 2017 18:58:09 GMT -6
Nah, I wouldn't worry about it.
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Post by illacov on May 14, 2017 20:12:35 GMT -6
I'm moreso curious to see if the great mystery has been solved somehow.
I remember when the ART Pro VLA was supposedly a dead end for mods and upgrades besides opamps and tubes for years and then I switched the Vactrol out. The entire unit was transformed. It escapes me why a component swap like that wasn't first on everyone's list but I sketched out the remainder of the mod with JJ and it literally turned what was once just a so so device into a gorgeous sounding tool for very little money.
If Svart is onto something, my tone is not meant to be confrontational it's more the pure curiosity and intrigue behind what he may have discovered. You know it's things like this that make these community-ish builds special. For all we know it could be a better grid resistor value or the way the PSU is calibrated. Better filtering caps in the PSU like films...yes films instead of electrolytics. This was from a guy I really respected. He built some really impressive mics so I'd defer to him anyway. Anyhoo. Popcorn popping!!
Thanks -L.
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Post by ragan on May 14, 2017 23:22:42 GMT -6
I must have missed some posts or something. I didn't see anything remotely dickish from svart.
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Post by kcatthedog on May 15, 2017 5:32:29 GMT -6
I'm with you Ragan. Frankly, Svart's fingernail knows more about t electronics than I do, so I read his comments carefully. Like illacov says implicitly above, there are so many possible vagaries to gear, that there is always the possibility some tech nerd like svart ( I say that most respectfully , could have figured something out or have a different experience. I have bought nothing but quality name nos brand tubes, even have a second pair of eriksonns with one fine: one noisy as shit :go figure All other tubes supplied tested from the British source have been fine, so I leave them in and the mike alone.
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Post by jin167 on May 15, 2017 6:08:51 GMT -6
It's just like church people getting really mad when physicists and engineers point out the fact that some of the phenomena in the bible are not physically possible and should be interpreted in a symbolic manner. Sometimes simply stating a fact can rub people the wrong way.
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Post by Johnkenn on May 15, 2017 6:29:56 GMT -6
It would be great if svart found something that myself and others have missed. It still does not explain why I had to go through 50-60 tubes to find a few pairs that were useable. If something was wrong with my build, no pairs of tubes would end up being quiet. Meaning the problem would follow the mic regardless of what was put into it. I do find some of the tone of this thread to be reminiscent of GS. Makes me feel like I should take a break from this forum. Really, dude?
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ericn
Temp
Balance Engineer
Posts: 14,934
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Post by ericn on May 15, 2017 6:34:40 GMT -6
It would be great if svart found something that myself and others have missed. It still does not explain why I had to go through 50-60 tubes to find a few pairs that were useable. If something was wrong with my build, no pairs of tubes would end up being quiet. Meaning the problem would follow the mic regardless of what was put into it. I do find some of the tone of this thread to be reminiscent of GS. Makes me feel like I should take a break from this forum. Really, dude? It's called an olive branch and yeah if Chris can find what Dan & Scott can't hey we call it science, so often fresh eyes see the solution!
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Post by Johnkenn on May 15, 2017 6:35:43 GMT -6
That was soooo passive aggressive.
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ericn
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Balance Engineer
Posts: 14,934
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Post by ericn on May 15, 2017 6:36:55 GMT -6
That was soooo passive aggressive. Sorry ! It was meant to be sarcasticly passive!
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Post by Johnkenn on May 15, 2017 6:50:00 GMT -6
That was soooo passive aggressive. Sorry ! It was meant to be sarcasticly passive! I'm talking about Scott's post.
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ericn
Temp
Balance Engineer
Posts: 14,934
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Post by ericn on May 15, 2017 6:55:14 GMT -6
Sorry ! It was meant to be sarcasticly passive! I'm talking about Scott's post. Ah well what can I say I woke up with a big head, or at least one that felt big!
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Post by kcatthedog on May 15, 2017 8:03:36 GMT -6
I was wondering if we could now focus on confirming if we have a solution to the 408 mystery !
Many of us have invested a chunk o change in this 47 power model,am very interested to know if there is a solution offing ?
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Post by sll on May 15, 2017 8:06:16 GMT -6
Sorry ! It was meant to be sarcasticly passive! I'm talking about Scott's post. Perhaps it was. I apologize for that. However, I felt that svart was implying that I didn't know what I was talking about. That there couldn't possibly be any issues with these tubes. My experience was completely different. I've built a few microphones and other high impedance devices in my time. I know where the trouble areas can occur. This boiled down to the tubes for me. Maybe I was expecting them to perform better than they did? They are certainly not as quiet as an EF86 or 6072.
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Post by Johnkenn on May 15, 2017 8:17:30 GMT -6
I'm talking about Scott's post. Perhaps it was. I apologize for that. However, I felt that svart was implying that I didn't know what I was talking about. That there couldn't possibly be any issues with these tubes. My experience was completely different. I've built a few microphones and other high impedance devices in my time. I know where the trouble areas can occur. This boiled down to the tubes for me. Maybe I was expecting them to perform better than they did? They are certainly not as quiet as an EF86 or 6072. No - I get it...I thought Svart was being condescending and yes, I posted that up above. I had the MK47 MkII for a hot minute and I think I had some noise issues too...although the RCA gold pin 408s seemed to work much better. There's no doubt you know what you're doing and I would hate for you to not contribute here just because of a post.
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Post by EmRR on May 15, 2017 8:37:02 GMT -6
Tangent...reminds me of the WE 417A tube, which by most measures should be an outstanding vey low noise preamp tube, one of the very few that might couple to a mic output directly without a transformer, yet reports from some solid commercial tube amp designers indicate they are good for a number of months before becoming noisy. High transconductance makes oscillation-free design more challenging.
It would be good to see some exchange of files/tubes/dialog between svart and others, see if any new data presents.
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Post by sll on May 15, 2017 8:40:04 GMT -6
Perhaps it was. I apologize for that. However, I felt that svart was implying that I didn't know what I was talking about. That there couldn't possibly be any issues with these tubes. My experience was completely different. I've built a few microphones and other high impedance devices in my time. I know where the trouble areas can occur. This boiled down to the tubes for me. Maybe I was expecting them to perform better than they did? They are certainly not as quiet as an EF86 or 6072. No - I get it...I thought Svart was being condescending and yes, I posted that up above. I had the MK47 MkII for a hot minute and I think I had some noise issues too...although the RCA gold pin 408s seemed to work much better. There's no doubt you know what you're doing and I would hate for you to not contribute here just because of a post. Thanks John. I probably should have cooled off a bit before posting that response in the first place. I would really like to make that mic quiet as I think it sounds really good. Just can't get past the noise. Drum overheads, electric gtr cabinet, great. Maybe one pass as a vocal mic in a dense track? Otherwise, I just couldn't use it. If I get more time, I'll have to put mine back together and do more testing. I got so frustrated with it, it's in pieces in a box right now. It would be great if we could move forward with this thread to find a solution to the problems some of us are having with this mic.
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Post by jcoutu1 on May 15, 2017 9:09:16 GMT -6
I'm interested in hearing more about the PCB's/Projects/Etc. My understanding is that there is an MK-47 and an MKU-47 right? The two mics are the same dual tube layout, but the MKU-47 features the fancy headbasket/pattern switching from Flea right? Are there other differences between these mics? Do they use the same PCB? Also, both of these are Max designs? Where does the Dany PCB fit in? Stam is using a PCB from Dany, not Max right? svart, did you make your own PCB, or were you using one of these? When I ordered this thing, I was thinking it was the same mic that tonycamphd (wish he was back around, honestly) built for Johnkenn, but with a Heiserman cap and without the fancy metalwork. Is this actually a different design?
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Post by ragan on May 15, 2017 9:17:15 GMT -6
It's just like church people getting really mad when physicists and engineers point out the fact that some of the phenomena in the bible are not physically possible and should be interpreted in a symbolic manner. Sometimes simply stating a fact can rub people the wrong way. Just as a point of fact, religious claims are not "such and such miraculous thing happened and we think that makes perfect sense within the laws of physics". If the alleged "miracle" were thought to jive with what we know to be the normal laws of physics, it would immediately cease to be "miraculous". May seem like a small quibble, but it's a really common oversight and makes for unproductive, confused dialog. Religion and science ask two fundamentally different questions. It's like looking at a baseball game. One is asking "what are the rules of this game?" and the other is asking "why is all this stuff here?" The religious claims may of course be wrong, but if one is going to refute them, they should at least refute the actual claim, not a straw man version. "The virgin birth is impossible because science" isn't a valid refutation because the claim was never "a virgin had a baby in the normal course of human biology". The claim has always been "a virgin had a baby because a power who is not bound by the natural, physical world intervened and made it happen". You can certainly validly say "well I don't think there is such a power" and then you're refuting the actual claim. Granted, it's a philosophical refutation and not a scientific one, but there's nothing wrong with that. The person saying "I believe in God" isn't making a scientific claim and neither is the person saying "there's no God". Science would never say "I don't have evidence for X and therefore it can't exist". It stops at the "no evidence" part because of its own fundamental rules. Anyway. I don't get remotely emotional about it but I know it can be a hot button thing for some people, on either side. But, to me, it's a massively important distinction to make clear.
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Post by svart on May 15, 2017 9:21:53 GMT -6
I'm talking about Scott's post. Perhaps it was. I apologize for that. However, I felt that svart was implying that I didn't know what I was talking about. That there couldn't possibly be any issues with these tubes. My experience was completely different. I've built a few microphones and other high impedance devices in my time. I know where the trouble areas can occur. This boiled down to the tubes for me. Maybe I was expecting them to perform better than they did? They are certainly not as quiet as an EF86 or 6072. I'm sorry you thought that. It was not my intention. I'm an engineer, so I'm not real good with the whole communication thing. :\ What I was trying to say is that it seems like the design in general teeters on the edge of stability and with different builds some choices in parts can inadvertently push the system into complete instability. Since tubes are a very loose tolerance device, you're going to have a huge spread of operating conditions, and therefor a huge chance for some tubes to work perfectly well, while others don't work at all. This bell curve can move around depending on the builder's choices. It seems that in your case I think the system is on one end of the curve, so that selection of tubes is necessary to find ones with the right operating attributes to fit the stability of the system. Other folks have had very little trouble with random tubes, which shows that the system has a very large spread of stability. I wasn't trying to point fingers at you personally, just using your experience as a data point in the larger discussion. I still think that needing to select tubes for stability is a symptom of an overall design issue, but the great variation in different builds makes it hard to pinpoint a specific difference that makes things work (or not work). I think that with some experimentation and troubleshooting we could likely bring the success rate with random tubes to much higher level. Currently I think that maybe the bias point of the plate might be iffy depending on B+ and heater currents. The U47 doesn't use a cathode bypass cap, so the AC signal will vary on the cathode and could cause instability here. I'll have to disassemble my mic to see, but I think I ended up using something like 25R in place of the 29R, and then adjusted the B+ until I got a good operating point. In at least *one* Neumann schematic, they show a 68R and 29R in parallel, which would equal ~21R. This in itself could add stability to the design if some tubes had higher GBW sending them off into oscillation.
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Post by svart on May 15, 2017 9:25:09 GMT -6
I'm interested in hearing more about the PCB's/Projects/Etc. My understanding is that there is an MK-47 and an MKU-47 right? The two mics are the same dual tube layout, but the MKU-47 features the fancy headbasket/pattern switching from Flea right? Are there other differences between these mics? Do they use the same PCB? Also, both of these are Max designs? Where does the Dany PCB fit in? Stam is using a PCB from Dany, not Max right? svart , did you make your own PCB, or were you using one of these? When I ordered this thing, I was thinking it was the same mic that tonycamphd (wish he was back around, honestly) built for Johnkenn , but with a Heiserman cap and without the fancy metalwork. Is this actually a different design? I initially bought a PCB (don't remember who from, but it's blue), but had to abandon a straight build due to the smaller mic body I used. I cut up the PCB and mainly used it to hold the tubes and a few resistors. The rest is either zip-tied or bolted to the metalwork.
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Post by kcatthedog on May 15, 2017 9:26:45 GMT -6
I'm interested in hearing more about the PCB's/Projects/Etc. My understanding is that there is an MK-47 and an MKU-47 right? The two mics are the same dual tube layout, but the MKU-47 features the fancy headbasket/pattern switching from Flea right? Are there other differences between these mics? Do they use the same PCB? Also, both of these are Max designs? Where does the Dany PCB fit in? Stam is using a PCB from Dany, not Max right? svart , did you make your own PCB, or were you using one of these? When I ordered this thing, I was thinking it was the same mic that tonycamphd (wish he was back around, honestly) built for Johnkenn , but with a Heiserman cap and without the fancy metalwork. Is this actually a different design? I could stand to be corrected but I don't think the Stam/danny mike is the same as max's 47, like Tony had at first or the follow up mk-u47. It seems to me based on the pics that the psu's are different, as well. Why does the Stam psu have a tube in it ? Is it following the neumann schematic exaclty ? I ask only because I think Max's does ? Not implying there is anything wrong with the Stam 47 mike: just curious to understand the differences.
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