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Post by Vincent R. on Dec 18, 2016 9:45:03 GMT -6
I'm not sure if this was discussed on another post, but this is something new to me. What specifications should I be looking for when replacing a tube for a microphone or preamp? It's great that so many sellers include the ratings and such, but I just don't know what any of it means. Is there a good site or article somewhere that could educate me on this topic?
Thanks, Vincent
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Post by tasteliketape on Dec 18, 2016 9:52:26 GMT -6
low noise and microphonics . The member "Bowie " sells tubes and great resource .
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Post by Johnkenn on Dec 18, 2016 10:02:39 GMT -6
bowie can guide you to the best NOS alternative for whatever you need. He was dead on about the GE and Mullard for my 251 (I'm gonna be one of those guys and officially pretend like a I have a 251 from now on...not an Upton 251)
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Post by jcoutu1 on Dec 18, 2016 10:08:15 GMT -6
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Post by chasmanian on Dec 18, 2016 10:26:43 GMT -6
talk to bowie, for sure.
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ericn
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Post by ericn on Dec 18, 2016 11:29:07 GMT -6
Another + for Bowie, or you can spend more time and money and not be anywhere near as happy!
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Post by kcatthedog on Dec 18, 2016 11:50:40 GMT -6
yup all good tube roads lead to bowie !
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Post by ben on Dec 18, 2016 15:37:07 GMT -6
+1. I've gotten a few nos tubes from bowie and they've all been top notch.
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Post by drbill on Dec 18, 2016 15:53:41 GMT -6
So we should be looking towards bowie then? Seriously, he's the man. The tube man.
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Post by bowie on Dec 18, 2016 15:59:21 GMT -6
Thank you all for the kind words. It's truly humbling to have such support. Tube selection is a tricky thing. People tend to think of them a bulbs, that they're either "good" or "bad", but there are many, many factors at play. Rather than just recommending specific types, I'll try to give a general primer that gives a bit of a "bigger picture" view of tubes and tube selection.
NOS vs Modern; Tubes are something of a novelty today compared to times when they were powered the world, and governments were putting serious money into tube development. Countries like Russia and China (which produce the majority of tubes today) never caught up with the US and Europe when it came to tube technology, nor did they inherit the techniques used. It would seem simple enough to reverse engineer such things in today's day and age but, with little R&D budget for tubes now, the quality is lacking these days. Not just the designs, but the labor, materials, and the fact that environmental regulations have changed the game a bit too. This translates into things like a much shorter lifespan, diminished bandwidth, smearing of tone, less detail, poor saturation characteristics, etc. Modern tubes can sound just fine so don't take this as a flat-out dismissal. But, quality has changed. Just buying NOS isn't an easy solution either though. Prices are escalating every year while good ones get cherry picked and bad ones are re-circulated into the market. Not all "NOS" brands were good to begin with. There are plenty of mediocre vintage tubes. And, noise and other issues plague vintage and modern tubes alike. There are times when buying NOS is preferable, and there are plenty of situations when it makes sense to go with modern production instead. Just two examples; if your high-end mic takes a 12AT7, it completely makes sense to get a good NOS piece. If your low-end guitar amp needs EL34s, I highly recommend modern options as NOS EL34s have become painfully expensive and most of what is left out there is used or B-stock.
Criteria; Even seemingly identical tubes from the same batch can vary in "strength" (including how they bias at various voltages), noise (hiss, hum, crackle, microphonics, etc), tone, health (gas, cathode leaks, etc), and certain other behaviors. It's helpful to know what the circuit requires. For instance, let's take an amp. An expensive, low noise selected British Mullard 12AX7 might sound beautiful in an input stage. But, if it's not balanced, it could be a poor choice for the phase inverter stage of the same amp, and would be a big waste of money. Likewise, a great tube selected for the phase inverter might be too noisy for the input stage. In pro-audio, our biggest struggle with tubes is noise. You'll see tubes advertised as "low noise", but keep in mind that the major consumers of tubes are casual guitarists and home stereo enthusiasts. Their gear usually doesn't have anywhere near the same noise sensitivity as something like a mic and they aren't seriously compressing, EQing, and amplifying the signal several times in a row through mixing and mastering. A tube that's severely noisy in a mic might sound dead-quiet in a Fender Champ. This can be problematic for the audio engineer who is buying tubes as the standards for "low noise", as defined by most tube dealers, falls far short of what the engineer might need and dealers usually don't have the equipment to detect low level noises. You may have heard mic techs saying they went through something like 10 tubes to find an ideal one. I recall a conversation with a major mic manufacturer who asked me about 6072 selection. He had acquired several hundred from a supplier and was shocked that this "microphone tube" (as it's often called) had such a low yield. In most cases, low level tube noise is normal and the tubes are useable in most gear. Certain types of gear, more specifically, certain portions of those circuits, just require a very careful selection of tubes.
Testing; I've tested thousands of tubes and the longer I do it, the more complicated it seems to get as I'm always finding other ways in which a tube can go wrong. I miss the days of blissful ignorance when I would stick a tube in the tester and it would tell me how strong, and/or noisy a tube was. I quickly found that the results somehow weren't translating in application. Unfortunately, the vintage units that make up 99% of the testers out there do a poor job at determining tube strength, matching, noise, etc. If you have the technical savvy, you can test the tubes in the actual circuit (the gear) but that's a bit beyond what most engineers are willing or able to do for each tube change. Good testers, that will run the tubes at real-world voltages and meter it accurately, will run several hundred dollars. Even then, you'll find many quirks in each tester that make them untrustworthy in certain areas. At nearly $3k, you can get a digital Amplitrex tester that you can program to test at the bias points you will see in-circuit, it runs the only decent gas and leak test I've ever seen, and will give very accurate testing and matching. But, you still have to have to know how to interpret the results. It has quirks of it's own. It can't detect low-level noise that's relevant in pro-audio. Can't check the quality of tone. And, you can't get around the fact that tubes do not start at "100%" and go down to zero. Determining strength and life requires a lot of experience with various types and brands (as well as some educated guessowrk). To complicate things, tubes change as they burn in initially. They may drift in strength, become quieter, noisier, the tone changes, etc. I've seen perfectly matched pairs drift to being terribly matched after just a few hours. Also, tone can vary as well, even when the tubes look identical. I don't say these things to dissuade people from getting into testing their own tubes. I think it can be fascinating, and a lot of fun. The above are just some of the things I deal with on a day to day basis when screening tubes for pro-audio applications.
Acquiring; Full disclosure; I deal in tubes. But, I will make every effort to give you unbiased advice here and people can feel free to speak up if they disagree. The 3 main ways of buying tubes will be to either; 1) find or buy untested/minimally tested and do the screening yourself, 2) get them from a dealer who has done normal level testing and see if they are satisfactory in your gear, 3) get them from a gear tech who screens them in the actual gear or something similar. The price of the tubes tends to go up as you travel from option 1 to option 3, though it never ceases to amaze me the number of high-priced/minimally tested tubes out there too. The reason this all isn't easier is that most dealers have no interest in setting up the type of equipment required to screen tubes for pro-audio use. It's much easier to do normal testing and deal with returns than spend the money and time on screening. It's hard to stay profitable when you require a lot of equipment and have low product yield (as my wife frequently reminds me).
If I can answer any questions, just let me know. I love sharing information on forums but I don't feel right about self-promoting on them so if anyone wants to inquire about specific brand recommendations or about buying tubes, please email me at ProAudioTubes at aol.com instead. -Christian "Bowie" Whitmore
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Post by tasteliketape on Dec 18, 2016 16:25:13 GMT -6
I sent my neumann m582 to Korby years ago for service,they tried so many tubes in it that didn't meet low noise requirements that there vender at that time wouldn't send them anymore . They called me to ask what to do . I called Bowie bought three tubes and sent to Korby . Was told by Korby it was the quietest tube they ever delt with. CALL BOWIE
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Post by chasmanian on Dec 18, 2016 16:31:59 GMT -6
yup all good tube roads lead to bowie ! I agree, man. extremely happy with all purchases from bowie. highly recommend giving him a call.
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Post by kcatthedog on Dec 18, 2016 18:38:32 GMT -6
Johnkenn,
can you make bowie's great little essay a sticky ?
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Post by johneppstein on Dec 19, 2016 0:22:54 GMT -6
I'm not sure if this was discussed on another post, but this is something new to me. What specifications should I be looking for when replacing a tube for a microphone or preamp? It's great that so many sellers include the ratings and such, but I just don't know what any of it means. Is there a good site or article somewhere that could educate me on this topic? Thanks, Vincent "Specifications"? Seriously? Printed specs don't mean much. Essentially, the printed "specs" you see for any brand of a specific type will be pretty much the same. You need to talk to people and find out what they think of specific brands of any given type. There's a lot of opinion, so you need to figure out who you can trust. Or spend a lot of money trying things out to find out what YOU like. And even within one specific brand and model there can be a fair amount of variation, so you need to know and trust your dealer. Bowie has a very good rep.
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Post by Vincent R. on Dec 19, 2016 7:52:22 GMT -6
"Specifications"? Seriously? Printed specs don't mean much. Essentially, the printed "specs" you see for any brand of a specific type will be pretty much the same. You need to talk to people and find out what they think of specific brands of any given type. There's a lot of opinion, so you need to figure out who you can trust. Or spend a lot of money trying things out to find out what YOU like. And even within one specific brand and model there can be a fair amount of variation, so you need to know and trust your dealer. Bowie has a very good rep. As I said in the beginning of the post, I really don't know what I'm looking for. I kept come across ratings for many NOS tubes and had no idea what any of it meant. Looks like the correct answer is to find a good dealer and utilize their knowledge to find what you're looking for. Bowie's explanation above is extremely helpful.
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Post by Ward on Dec 19, 2016 8:40:00 GMT -6
I'm not sure if this was discussed on another post, but this is something new to me. What specifications should I be looking for when replacing a tube for a microphone or preamp? It's great that so many sellers include the ratings and such, but I just don't know what any of it means. Is there a good site or article somewhere that could educate me on this topic? Thanks, Vincent "Specifications"? Seriously? Printed specs don't mean much. Essentially, the printed "specs" you see for any brand of a specific type will be pretty much the same. You need to talk to people and find out what they think of specific brands of any given type. There's a lot of opinion, so you need to figure out who you can trust. Or spend a lot of money trying things out to find out what YOU like. And even within one specific brand and model there can be a fair amount of variation, so you need to know and trust your dealer. Bowie has a very good rep. Hang on now, johneppstein. There could be very good reasons for someone looking for specs. The poster might not be quite as familiar with tubes as you (or I) might be . . . perhaps the poster might also not be certain of the exact tube type he needs. I can remember being a nubile at tubes/valves and thinking every 12--7 slot could easily be filled with a 12ax7. I wasn't familiar with the differences between T U W X and Y variants. Someone might also not be completely familiar with the 6027 type and looking for some sort of variant options. Ward
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Post by johneppstein on Dec 19, 2016 12:07:29 GMT -6
"Specifications"? Seriously? Printed specs don't mean much. Essentially, the printed "specs" you see for any brand of a specific type will be pretty much the same. You need to talk to people and find out what they think of specific brands of any given type. There's a lot of opinion, so you need to figure out who you can trust. Or spend a lot of money trying things out to find out what YOU like. And even within one specific brand and model there can be a fair amount of variation, so you need to know and trust your dealer. Bowie has a very good rep. Hang on now, johneppstein . There could be very good reasons for someone looking for specs. The poster might not be quite as familiar with tubes as you (or I) might be . . . perhaps the poster might also not be certain of the exact tube type he needs. I can remember being a nubile at tubes/valves and thinking every 12--7 slot could easily be filled with a 12ax7. I wasn't familiar with the differences between T U W X and Y variants. Someone might also not be completely familiar with the 6027 type and looking for some sort of variant options. Ward Well, the thing is that the spec sheet for a given tube type is going to be the same from pretty much any manufacturer because the specs are standardized. Essentially they're of interest to someone designing gear but useless to sombody trying to figure out which tube of a given type might be best to use in somebody's mic or preamp, as there's really nothing ion the specs that tells you what the tube sounds like. There's not even any noise spec, no spec for microphonics, and certainly no spec for sound quality. The question was And the answer to that is "spec sheets aren't useful for that" unless he's looking to change the performance of the circuit and even then they're not all that useful with the exception of the rated gain and the pinout. There's nothing in the spec sheet to indicate wheter a GE might be better than an RCA or a Sylvania, or that a NOS tube might or might not sound better than a new one from Russia or China. And in such matters, "better" is often a moving target. Talking to a guy like Bowie is a lot more illuminating than poring over a bunch of essentially identical spec sheets. BTW, didn't you mean "6072"? A 6027 is a pulse magnetron - not real useful for audio.
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ericn
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Post by ericn on Dec 19, 2016 19:00:13 GMT -6
Hang on now, johneppstein . There could be very good reasons for someone looking for specs. The poster might not be quite as familiar with tubes as you (or I) might be . . . perhaps the poster might also not be certain of the exact tube type he needs. I can remember being a nubile at tubes/valves and thinking every 12--7 slot could easily be filled with a 12ax7. I wasn't familiar with the differences between T U W X and Y variants. Someone might also not be completely familiar with the 6027 type and looking for some sort of variant options. Ward Well, the thing is that the spec sheet for a given tube type is going to be the same from pretty much any manufacturer because the specs are standardized. Essentially they're of interest to someone designing gear but useless to sombody trying to figure out which tube of a given type might be best to use in somebody's mic or preamp, as there's really nothing ion the specs that tells you what the tube sounds like. There's not even any noise spec, no spec for microphonics, and certainly no spec for sound quality. The question was And the answer to that is "spec sheets aren't useful for that" unless he's looking to change the performance of the circuit and even then they're not all that useful with the exception of the rated gain and the pinout. There's nothing in the spec sheet to indicate wheter a GE might be better than an RCA or a Sylvania, or that a NOS tube might or might not sound better than a new one from Russia or China. And in such matters, "better" is often a moving target. Talking to a guy like Bowie is a lot more illuminating than poring over a bunch of essentially identical spec sheets. BTW, didn't you mean "6072"? A 6027 is a pulse magnetron - not real useful for audio. Yeah the sheet is great for telling what you need! BUT like anything you might find on the net be carful I have seen a number of new resources and "edited " editions of old stuff with stupid errors So check your sources ! Or just F'ing get a hold of Bowie!!
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Post by Ward on Dec 19, 2016 19:27:53 GMT -6
BTW, didn't you mean "6072"? A 6027 is a pulse magnetron - not real useful for audio. umm, well yes, I have just demonstrated I type too fast and miss typos! LOL
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Post by johneppstein on Dec 20, 2016 2:22:11 GMT -6
BTW, didn't you mean "6072"? A 6027 is a pulse magnetron - not real useful for audio. umm, well yes, I have just demonstrated I type too fast and miss typos! LOL Yeah, me too - in my case not really speed, but my guitar picking fingernails cause problems. I spend as much proofreading as I do typing and even so have to keep going back and fixing stuff - that's why you'll rarely see one of my posts that hasn't been edited several times.
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Post by EmRR on Dec 20, 2016 8:49:29 GMT -6
autocorrect is the worst
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Post by svart on Dec 20, 2016 9:41:36 GMT -6
I'mma be that guy..
I tried multiple tubes in my mics and amps.. NOS.. New manufacture.. Unused.. Broken in.. Different brands, you name it.
Honestly they didn't sound all that different, even ones that are supposedly notorious for being noisy were pretty quiet. I ended up using JJ tubes for most preamp applications in the mics and amps in the studio and haven't had much trouble at all.
Some have been microphonic, but that's usually a tube-to-tube thing, rather than a brand or model thing.
This also doesn't account for break up. This is where I find tubes can be drastically different in tone, during stress.
Also, power tubes seemed to make a much greater difference in overall tone in amps than preamp tubes did when you don't consider breakup.
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Post by Johnkenn on Dec 20, 2016 11:00:27 GMT -6
I certainly noticed a difference in the different tube in my Upton...and I heard it in the MK47II I had...but say - like my sta-level...I'm really not sure I hear a difference in my NOS GE 5* 6386 and the JJ 6386
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Post by johneppstein on Dec 20, 2016 23:01:49 GMT -6
I don't post from my phone. Ever. I have computers for that.
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Post by Quint on Dec 20, 2016 23:13:08 GMT -6
Here's my question to Mr. Bowie (glad you joined the forum). Who is your apprentice that you are training that I can contact when you decide to hang it up and retire? You obviously are THE tube authority and I hugely respect that. I've been meaning to get a hold of you to buy a few tubes. But what am I gonna do when people with your knowledge go away?
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