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Dirty-South Blues Harp forum: wail on! >
6v6 power tubes
6v6 power tubes
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528hemi
311 posts
Sep 22, 2012
4:42 PM
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I have 2 6v6 tubes in my magnatone. Class AB push pull
1 tube test pretty strong the other passes but not as strong. Would say it is acceptable but not much more.
Will putting in 2 fresh tubes boost the output where I would really notice a big difference?
528hemi
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LSC
305 posts
Sep 22, 2012
6:01 PM
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Depends on your ears. Also depends on the tubes and to a certain degree the competence of the amp tech. The new tubes will require the amp be biased. I usually have an amp gone through and serviced at the same time. Most guys charge a minimum bench fee and it doesn't take an hour to bias an amp. Might as well get your money's worth.
There is much debate as to the value of NOS tubes over contemporary brands. Modern tubes that I've tried and found to be the best are JJ and TAD. Having said that I am absolutely sold on NOS tubes. They simply sound better to me in a very noticeable way. Consensus is they are also more reliable and last longer which makes them a better value in the long run.
For any American amp power tubes NOS RCA are my favorites. Most people think the blackplate version are the ultimate and I would agree. But they are expensive. You see crazy asking prices, but shopping around will show you don't have to take out a bank loan. The grey plates are somewhat cheaper and run a close 2nd. There are also brands that are RCA but labeled something else. They tend to be a bit less.
There are various versions of the 6V6, most all of which I believe would work with the Magnatone but some will better than others. Pretty easy to find out. I'm sure you'll get some of the techie guys on this forum to way in. There is also a Magnatone specialist site that most likely has that information.
Just do a bit of research and you'll find all kinds of stuff. Do be aware that some of the forums you'll come across will have all kinds of opinions and it can get confusing after a while. Just make your own choice between modern or vintage and how much you want to pay.
BTW, I may have a pair of barely used JJ 6v6s for sale soon.
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LSC
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Joe_L
2065 posts
Sep 22, 2012
6:13 PM
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Buy a pair of JJ's 6V6's from eurotubes.com. they are cheap and good. I've got them in my Champ clone and the Double Trouble. They sound great.
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Last Edited by on Sep 22, 2012 6:21 PM
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Joey Anchors
5 posts
Sep 22, 2012
6:12 PM
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I agree about the JJ's. I have a pair of them in my amp and they sound huge!
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"The dirtier the better"
~Joey
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bloozefish
50 posts
Sep 23, 2012
7:14 AM
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I'm pretty sure that the Maggie is cathode biased, so a rebias is not necessary with an output tube change. Check out the Yahoo Magnatone-Valco group....lots of folks with outstanding experience with Maggies.
Just an opinion, but I think matched pairs of tubes are largely hype. I 'spect others will chime in here with their experiences.
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5F6H
1379 posts
Sep 23, 2012
9:46 AM
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Bloozefish "Just an opinion, but I think matched pairs of tubes are largely hype. I 'spect others will chime in here with their experiences."
Matched tubes are simply tubes that match by idle bias current (vendors usually quote transconductance too, but I have never heard of anyone who could hear a match/mismatch based on transconductance alone)...beyond that they don't even have to come from the same manufacturer. Within +/-15% is what most tube vendors would call "matched", you are lucky if a vendor can match to the milliamp, but some do.
Most people can hear the difference between a perfect match & significant mismatch (some amps, like Kendrick & Peavey deliberately mismatch the push-pull output to create a certain character, this can be done various ways by circuitry, or simply by mismatching power tubes' bias - making sure not to cook the hotter tube). Whether you prefer a match, or a mismatch depends on what you are shooting for tonally.
It makes sense with fixed bias amps to buy matched pairs so that, to get a good average, one tube is not greatly over ideal dissipation. If you are not running the amp in the "normal/hot" zone this becomes less of an issue technically and more of a tonal preference.
Amp power ratings usually assume a substantial match, as this will give best clean power...but not everyone wants best clean power! ;-)
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bloozefish
51 posts
Sep 24, 2012
10:31 AM
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5F6H,
many thanks for the schooling. What you say makes perfect sense for a fixed-bias circuit, especially if you want a cleaner platform for pedals, etc.
My experience was in comparing matched pairs w/ unmatched (but good and tested in a SE amp) pairs in a cathode-bias amp...the unmatched pair sounded warmer to my ears, but indeed less clean.
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Rockerduck
33 posts
Sep 24, 2012
1:41 PM
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A JJ "S" 6V6 is a louder, more 6l6 type tube. It will need to be biased higher and requires more plate voltage and it is hard to kill. If you want to just put in some Ruby 6V6 tubes, I doubt the bias will need to be changed. The plate voltage will likely match up and stay within the 70% dissipation of the tube wattage.
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5F6H
1381 posts
Sep 24, 2012
2:24 PM
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JJ6V6 don't need to be biased any hotter than any other 14W 6V6 type tube, it's sturdy but it's still a 14W 6V6. In cathode biased amps the bias is largely set by the cathode resistor, there is some variation between tubes, even of the same brand, but not enough usually for a specific brand of tube to be obsolete. Cathode-biased, push-pull amps, especially 50's & 60's amps usually run their 6V6s at well over 70% dissipation, often more like 90-110%. 70% is more in line with fixed bias dissipations.
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tmf714
1277 posts
Sep 24, 2012
2:51 PM
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Review Notes
By John Templeton
JJ 6V6S - In addition to JJ’s other robust line of power tubes, a 6V6 is being produced that is extremely good. There is no longer a need to search out expensive NOS that have been picked over for 20 years. While there is a market for the NOS product, you are no longer required to buy NOS in order to get really great results.
For about 6 months I have been torture testing the JJ 6V6 in guitar amplifiers. That not only includes using them, but putting them in real life working situations. They have been subject to rough handling, over biasing and under biasing in amps with plate voltages ranging from 380 – 475 VDC. The tubes would not die and the matching on them drifted less than 2 ma over the life of the test. That’s about six months of continuous use and abuse.
How do they sound? That’s probably the most important question and a very easy one to answer. These tubes sound great, period. They do clean with smooth clear high end. On the other end of the spectrum big fat bass notes that are well defined having a piano like quality are produced. Crank up the gain and you will get everything from a nice crunch to all out screaming distortion. And not just mush, but a very controllable, musical distortion. A well tuned amp running the JJ 6V6 and getting a good strong signal from your guitar may make you want to cash in your old TS808. One rig that was used as a tester consisted of a ‘66 Deluxe Reverb fitted with a Celestion Vintage 30. The JJ’s were put in with a plate voltage of 440 volts and biased at about 80% of their rated output. This would kill many tubes (and had in the past). A current production Les Paul Standard was plugged in and the resulting sound could only be described as “crazy”. Just about any genre of music from blues, jazz to classic rock was obtained.
If you are a guitar picker with a love for tone you owe it to yourself to try a set of these outstanding tubes.
A. F. BEAM PENTODE
Base: OCTAL
Uf = 6,3 V
If = ca 0,5 A
Typical
characteristic: Class A1
singl tube Push-Pull
Ua = 250 V 250 V
Ug2 = 250 V 250 V
Ug1 = -12,5 V -15 V
Ia = 45 mA 70 mA
Ig2 = 5 mA 13 mA
Ra = 50 k? -
Ra-a = - 10 k?
N = 4,5 W 10W
Limiting values:
Triode Pentode
Ua = 450 V 500 V
Ug2 = 450 V 450 V
Wa = 10 W 14 W
Grid No 1 Circuit Resistence
Fixed Bias 0,1 M? 0,1 M?
Self Bias 0,5 M? 0,5 M?
Capacitances:
Cg1 = 9 pF
Ca = 8,5 pF
Ca/g1 = 0,7 pF
Substitutes: 5871, 6AY5, 6P6C, 6V6G,
6V6GT, 6V6GTA, 6V6GTY, 6V6Y, 7184,
CV509, CV510, CV511, OSW3106, VT107,
VT227, WT2100082, WTT123, 7408
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Joey Anchors
8 posts
Sep 24, 2012
3:28 PM
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I am loving my JJ 6V6's :D
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"The dirtier the better"
~Joey
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