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Post by craggin on Dec 2, 2005 20:23:16 GMT -5
Well, it isn't the end of the world...but I was checking my tubes and noticed that the plastic centerpiece on the bottom of one of the tubes was broken. (It actually came completely off.) I don't know how long it was like that, but the tube is still intact with no leaks, etc.
Just to be on the safe side, I'm going to run it on half power...which two tubes are engaged when running the amp that way, the inner 2, correct?
The tube in question is the furthest EL34 from the input jack. Granted, the tube is still in tact and the prongs are in the correct sockets (I tested them and lined them up correctly) but I just want to be safe...
Any input...am I cool? Thanks.
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Post by Hacksaw on Dec 2, 2005 20:27:25 GMT -5
Ya, I am alsost 100% sure inner 2 tubes.. ( all amps I have ran across so far run that way when switched half). I am pretty sure splawn followed the standard A/B push pull config on these amps.
broken tube socket key guide?? I havent seen that one "yet", hope I dont, thats one of those things you dont know about until its too late usually. Nice catch!
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Post by craggin on Dec 2, 2005 20:33:48 GMT -5
Thanks Hacksaw...yep, it was the tube socket key. It broke off very cleanly...don't know how long it had been like that. I looked it over VERY thoroughly and noticed that there was no damage to the glass in the tube, so it was still sealed. I basically lined up the tube socket key with the tube and socket and figured out which pins went where and then installed the tube. I briefly powered up the amp and noticed the tube was getting juice and glowing fine, the went to standby and switched to half power. Looks like I'm in the market for some new tubes...hmmm, what shall I try...
Suggestions anyone (other than the obvious stock tubes)? I love trying new things. LOL!!!
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Post by jimbax on Dec 2, 2005 20:40:01 GMT -5
Dang Russian Tubes!!!! Communist Engineering!!!!
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Post by Hacksaw on Dec 2, 2005 20:46:10 GMT -5
mullards are hard to beat. though the russians make awesome tubes.. I only used the Svetlana's, or JJ's in every amp other than the splawn. I mainly ran Svetlanas 90% of all El34 amps.
LOL "dang Russian tubes" :-) mybe we send them some USA clay ??
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Post by craggin on Dec 2, 2005 23:23:45 GMT -5
I would agree that in the Quick Rod, the Mullards are hard to beat. In my JCM800 and Road King, I used SED's, Svetlana's, Ruby's, and a few NOS tubes. I really liked the Siemens 6CA7's a lot in the Marshall...but something tells me the Splawn's plate voltage might be pushing them too hard. I'll either get the Mullards or maybe try either the Ruby's or SED's.
The Quick Rod puts out a lot of "thump", something tells me I don't want a tube with a big bottom end as it could be overkill.
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Post by craggin on Dec 2, 2005 23:48:40 GMT -5
I should add, that the Svetlana's I used were the old ones.
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Post by Hacksaw on Dec 2, 2005 23:52:23 GMT -5
The svetlanas will handle the high voltages. bogner uses the Svetlana just because of the higher voltage. and recommend that only those tube brand be used.
I used JJ, and other tubes in my other amps.. I came back to the svet's and JJ's. let us know what you try if you change it up. as I havent tried anything but the Mullards in the splawn. I do have 6 sets of svetlanas, as I might try em one day.
What do you use to set your bias with? I use a Weber Biasrite Octal IV 2+2
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Post by craggin on Dec 3, 2005 0:10:48 GMT -5
Hacksaw, I use a Weber BR-AH with the VI option as I have a voltmeter. I'm leaning toward the SED Winged C's...but I saw a quad of Ei 6CA7's in a local shop not too long ago. The price was right on them, but I've heard people either swear by them or swear at them. :-)
As for the Bias Rite...aren't they sweet?
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Post by craggin on Dec 5, 2005 11:41:04 GMT -5
Okay...had a bear of a time trying to locate a matched quad of ANY brand of EL34's...let alone Mullards. Guitar Center had GT's and Mesa's...but I really prefer dealing with local shops as much as possible. Well, I sort of had my heart set on trying a quad of SED Winged "C" EL34's as they are the old Svetlana's. My last attempt was at a fairly large local shop in town and they were busy!!! (I rolled in there around 11:00 in the morning...I had rehearsal at 3:00)
The salesperson said "all I've got are these tubes that were sent to us...not even sure what brand they are". I pull one of the tubes, lo and behold, they've got that nice little silk screen "winged C" stamp on them. Only problem, they were a "loose" lot, not screened as a matched set. (There were about 12 of them.) So I visually inspect them and look at the various stamps on them and find 4 that are the same. I figure I'll take my chances and hope that they're all close enough. After getting home and installing them, I check and see they're all drawing 495v of plate current...cool, how about the cathode current? Well, unfortunately, they weren't a perfectly matched quad, but they all fell in a range of between 29.4mV to 33mV. (Two of them were EXACTLY 31.4mV) I figure that'll do for know.
Now, practice time comes and I figure the worst that'll happen is that a tube fails and I'll blow a fuse...it never happened, they worked perfectly. The SED's are a VERY nice alternative to the Mullards...very, very nice. I won't say they "smoked" the Mullards because I only played through them at volume for a few hours and I can't stand when people give glowing reviews after about 10 minutes of playing something. (Other than a QuickRod...that only took about 20 seconds...lol!!!)
The SED's have a very extended, smooth mid-range with a nice bottom end. The bottom end was more noticeable...it wasn't really better or worse...just "different". Not really deeper, either...just different. (I can't really put my finger on it.) The highs were pretty chimey, nice and musical, the way I really like them. The mids were fairly complex and had that old Marshall "snarl" to them.
For those not familiar with SED's, JSC Svetlana is a Russian company that owns and operates the Svetlana factory in St. Petersburg, Russia, which has been making vacuum tubes for almost a century. These tubes have been known in the United States as Svetlana brand tubes and have had the "S" logo and/or the logo (a Cyrillic S) on them. Because of a change in ownership of the former American distributor, JSC Svetlana recently lost its ability to sell vacuum tubes bearing the "Svetlana" name, while maintaining the ability to sell the tubes bearing the logo in the United States and Canada.
If you dig the Svetlana's that came in old Marshalls, you might want to give these a go.
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Post by jimbax on Dec 5, 2005 12:02:45 GMT -5
I had a Quad of NOS Mullards in my 'Guytron' amp a few years ago....cost major bank! and were a bit 'flat' and less power/volume than the Svetlana E34Ls...I was dissapointed until I ebayed them for the same amount I paid for em the Svetlana's are more 'vocal' but they are much 'noisier' too....I had 'Don Butler' in LA reBias the dang thang for me...something about high voltage step-up transformers, open circuitry, sweaty clumsy hands etc...I have already been shocked by a Marshall cap that had been setting 'off' for a few minutes.....ZZZZAAAAAPPP!
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Post by Hacksaw on Dec 5, 2005 12:09:03 GMT -5
Very Cool report!! Glad to know it wasnt a big change but a subtle one. The bias sounds pretty close enough for me. I dont mind a few ma differances. I have been told up to 4 or 5 ma is normal. Did you by chance check the factory mullards for ma ?? I would be curious how tolerant the bias is from factory. I havent checked mine yet, havent has the cover off except to install the tubes when I got the amp.
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Post by craggin on Dec 5, 2005 12:28:22 GMT -5
Thanks!!
Hacksaw, I did check the stock Mullards...3 were very tight, all around 30mV, but the 4th was around 36!!!! (I'm assuming there was a slight gas leak or something.) True, the difference between the SED's and stock Mullards was pretty subtle, like different shades of your favorite Levi's...know what I mean?
jimbax, those caps are pretty scary. I NEVER put both hands inside an amp...ever because you just never know. There was a thread on The Gear Page a while back written by a tech who recently got zapped by the caps as well (he said his hands were very sweaty)...and that's a guy who does it for a living. I always keep one eye on the caps whenever I bias my amp as there's something about having close to 500 volts running through my body that just doesn't seem right. For kicks, I sometimes watch my voltmeter and see how long it takes for power to drain from the tubes...that often takes more time than you'd think. Caps are a different beast in that they can store juice for a VERY long time.
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Post by Hacksaw on Dec 5, 2005 12:41:54 GMT -5
Craggin, yeaup I know what ya mean!! thats interesting.. I will have to try this too one day. just to see if the shade is more " cool". it does sound like the one tube was a little off. thanks for the reports!!
LOL... yes those amps have a bite!! when I was building the JTM45 I got bit.. hehe.. had a chassis ground issue.. yea it happens.. I told the wife if anything went wrong to call 911, and if I was still being electricuted, to knock me off with a board or something,, then I reiterated,, ONLY IF i am being electricuted.. LOL she was ready to help more than usual.
glad it didnt get me on my ring.. would of lost a important finger. remember to take those off!
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Post by craggin on Dec 5, 2005 12:46:18 GMT -5
glad it didnt get me on my ring.. would of lost a important finger. remember to take those off! GREAT point...I often forget that...
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