| Author | Message | ||
| Greg Williams (gwmn) Username: gwmn Registered: 08-2013 |
Well I just got through trying some new JJ 6CA7, double getters, in my 210-65, 12AX7 driver. Tried the bias at 19,22 and 25 and they sounded thin and brittle on all three. I put my old Sylvania, single getter, 6CA7's back in. World of difference. Smooth and musical compared to what I would call, very harsh. I did try different 12AX7's also with the new JJ's with the same results. I don't know what they were after with these tubes, but they are not similar to the old Sylvania's in my opinion. (I know..... that's expecting too much) Had similar results with some early 2000's winged C's. I need to find something close so maybe I'll try the JJ EL34's as I've heard some decent feedback on these. Just had high hopes for these JJ 6CA7's. One of my Sylvania's is weak and works great on the low setting but runs away in bias on the high. New tubes bias fine. Darn!! | ||
| Mike Kaus (mm210) Username: mm210 Registered: 05-2006 |
I know that the JJ tubes are historically tough. You might try warming them up even more. You MIGHT contact Bob at Eurotubes(don't know where you bought them) and ask HIM how hot they can run. I know he likes to torture stuff to death but you have to use his advice with a grain of salt. I would try them at 30 and even higher. they SAY they will 50mA but that is at something like 400V. Warm them up a little and see if it changes the sound. Here's the link to the 6CA7 data sheet. http://www.thetubestore.com/lib/thetubes tore/JJ-6CA7.pdf Mike. | ||
| Greg Williams (gwmn) Username: gwmn Registered: 08-2013 |
Thanks Mike, I'll call him tomorrow. I bought these from them. | ||
| Steve Kennedy (admin) Username: admin Registered: 03-2002 |
You might try the JJ E34L tube. It is sort of like having a tube that is between the 6CA7 and and EL34. I believe this is the JJ tube that Bob at EuroTubes suggests for the Music Man amps because it withstands the higher plate voltage better. Steve | ||
| Greg Williams (gwmn) Username: gwmn Registered: 08-2013 |
I've been eyeing up the L's and if the 6CA7's won't cooperate that's what I'll try. Only other option is to search for Sylvania's, though the stock has been picked over quite a few times already. One thing I forgot to mention that was kind of strange. The tremolo cycle with the JJ 6CA7's would fade completely in and out on 3 or more, as compared to the Sylvania's, which would sound the way it should. | ||
| Lars Verholt (lmv) Username: lmv Registered: 11-2009 |
Winged =C= EL-34 is another great option (albeit somewhat expensive). As I've said on this forum before, the premium 'cryo' version, in my opinion, is like paying extra for whitewalls on your tires. You may feel good about paying extra but it doesn't actually do anything ;o) Cheers, Lars Verholt | ||
| Greg Williams (gwmn) Username: gwmn Registered: 08-2013 |
I tried warming the bias up on the JJ 6CA7's and they won't adjust above 28, after 20 min, bias pot maxed. Maybe they'll work for clay pigeons. | ||
| Mike Kaus (mm210) Username: mm210 Registered: 05-2006 |
You CAN get them to go hotter. You just need to REDUCE the amount of - voltage going to the bias adjust pot. This will allow you to INCREASE the amount of current going through the tubes. Maybe put another 5K resistor in front of the bias pot to decrease the available control grid voltage. Mike | ||
| Greg Williams (gwmn) Username: gwmn Registered: 08-2013 |
Thanks Mike, I've got some 1/2w CC 5K's around here somewhere. By the way, I am retaining all of this usable knowledge you are passing along for future reference. By the time we're 90 I won't have to bug you anymore. | ||
| Greg Williams (gwmn) Username: gwmn Registered: 08-2013 |
Just talked to Eurotubes, Bob wasn't there until tomorrow, but the one I did speak with said not to go above 28. Hogwash! Got my helmet on headed for 30 plus!! I guess I better put the resistor in first. Only had a 4.7k | ||
| Mike Kaus (mm210) Username: mm210 Registered: 05-2006 |
I just looked up the actual 6CA7 tables and they work out to around what he said so MAYBE he was right. I figured the 6CA7's would take more than that. Stick with his suggestion. Mike. | ||
| Mike Kaus (mm210) Username: mm210 Registered: 05-2006 |
The more i look at that, I think MAYBE you should add the 5k or so AFTER the pot. THAT way it shouldn't muck up the voltage downstream that it needs for the +and- voltage for the IC's. Not that I think that it will make THAT much difference but it will effect the voltage before it dumps into the 100K dropping resistor. I'm just thinkin' here...... Gawd, it's hell to get old! Mike. | ||
| Greg Williams (gwmn) Username: gwmn Registered: 08-2013 |
I'll try that Mike, thanks. But first I need to wait on my probably foolish purchase of a pretty closely matched, (I hope), Sylvania 6CA7 to the one good one I have. Paid $55, it's a single getter like mine that looks good on paper. Wish "my" aging brain would let go of the tone obsession a little with this amp, but ever since I've heard it with these old Sylvania's it's hard to get it out of my head. I go just a little overboard with that sometimes. I just finished up a tweed champ build from scratch, (not a big fan of kits or sticking to the schem.), and I wore out screws,wire and turrets from changing things around so much, but found what I was after........I think. Thanks again Mike. | ||
| Greg Williams (gwmn) Username: gwmn Registered: 08-2013 |
Got my Sylvania 6CA7 and it worked out great. (A little prayer involved) Biased at 22 on both and it sounds wonerful - wonerful. Thanks again for all the help. |
Tue, 03/25/2014 - 09:54
#1
JJ 6CA7 comparison
E34L.....definitely the tube to use, was recommended by a tech about twelve years ago and it's made for Music Man amps.
Just curious if anybody
Just curious if anybody actually ordered and is using the new JJ 6CA7's. We've talked about it here but has it been tested yet? I haven't needed any MM tubes for a while so I sure haven't ordered any! Mike.
Is it a minor thing to
Is it a minor thing to convert from 6L6 tubes? I read somewhere that there is a pinout difference between the tubes. Mine is an 80's model, but was curious how it would sound with 6CA7's.
I was close to it ..
Hey Mike,
I was close to getting them when I ordered tubes yesterday - does that count?. In the end I ordered a set of Tung Sol reissue EL34 for my 65 112 Reverb and JJ 6L6 for the RD-50 110.
Will report on both sets when I get around to testing them.
PS - the reasons I didn't order my usual =C= tubes were:
1. Expensive! (especially considering the current exchange rate of the Canadian Lira)
2. Is it just me or does it make sense that whichever specimens are left in stock aren't getting better, only worse?
3. Did I mention, expensive?
Cheers,
Lars Verholt
I wouldn't even CONSIDER
I wouldn't even CONSIDER ordering "C"s anymore because of the cost AND you're right-you'd be getting leftovers. If I was playing more (ANY?), I'[d think about ordering a quad of 6CS7's just for giggle but I'm afraid my playing days are coming to a close here soon. Just no work for an old guitar player! I would get more work if I wanted to go back to playing bass but while fun, gets boring full time. Been there-survived that. Honestly, my main gigging amp lately has been the little vox NT15 (small box). 15 watts tube and with the way things have quieted down in the music worl, it's been plenty. My MM just stays down in the recording area. Mike.
JJ E34L
I have used MM amps for nearly 40 years,and for the last 15 years have only used JJ E34Ls They hold up to the high voltage very well. These amps need to be biased on high power mode,and bias set at around 21ma per valve. I use a 1975 MM 2x12 65. Only use on low power and it sings. Also have had 2x 130 combo,s in the past,and same settings.
Ordered JJ 6CA7s
A bit over a year ago (see above) I ordered Tung Sol reissue EL34s for my 65 112. I played two shows with them and always felt it was too dirty on the low setting and lacked punch on the hi setting. Eventually I also got a bad hum which I first thought to be something else entirely - these were almost brand new tubes, right? After many trials and swapping in older tubes (some of which had become unstable and needed to be forwarded to the bin) I found out that it was indeed the Tung Sols humming - at least that's my theory that I'm sticking to at the moment :o|
After reading Mike '210' Kaus' suggestion I ordered a set of JJ 6CA7 'fat boy' and I will report back on how they stack up.
As a sorta funny side note: I have avoided Chinese made tubes because I was afraid that they would be too prone to fail and take my precious MM amp out. My HD130R head came with Peavey branded tubes and has sounded fine to me - still does. When I last had this amp apart to fix something (documented in another post) I found out that these tubes are marked 'made in China' - I had thought that if nothing else, Peavey tubes would be Sovtek rebrands like everything else. Ya learn something new every day!
Sincerely
Lars Verholt
PS - thank you for all the clicks on the Facebook video of my band last week, my dashboard shows an 18,000% (yep 18 thousand) increase in videos watched over the previous week.
DAMN-I'm glad somebody
DAMN-I'm glad somebody ordered a set of those. I'm not playing anymore but really like to at least PRETEND to keep up. I'll be glad to hear what they sound like. Just curious Lars-where'd you get them? I hear horror stories about JJ's sometimes but they always seem to come from other places than Eurotubes. I don't have any failures with the Euro guys and have practically no failures with them . Just curious-not trying to steer anybody. Mike.
CE Distribution
I get my tubes mostly from the wholesaler CE Distribution in AZ. You have to run a business in the field of audio to buy from them. I think their retail outlet is tubesandmore.com .
Cheers,
Lars Verholt
Speaking of keeping up..
Mike, when did you last update the firmware in your amp? LOL!
WHICH ONE! Actually, the
WHICH ONE! Actually, the MM just got used to record some stuff. I have had the same set of JJ E34L's in there for years. THAT'S why i was wondering. Normally, 6CA7's are a little cleaner than E's and if need be, I could see my way into getting a pair to play with. Almost all the jobs I played up until my sort of retirement were done with the little Vox. But you never know when you're going to have to do an outdoor thing where you need some balls. Hell, I've still got the twin down there but I'm too damned old to pick it up! Mike.
All that's needed is a tax number!
My tech friend forced me to set up an account with CE before he left for greener pastures. Good folks, decent deals, and they are handling Eminence speakers now. I had a federal tax number for my auto repair business, so that allows me to order from them.