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Post by Hacksaw on Dec 5, 2005 13:15:30 GMT -5
Can you tell if the SED's are breaking up sooner that the mullards?
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Post by craggin on Dec 5, 2005 13:45:38 GMT -5
Can you tell if the SED's are breaking up sooner that the mullards? THAT'S IT!!!! Remember when I said I couldn't put my finger on the bottom end...it was the breakup!!! It didn't have as big of a bottom end (very close, but not quite) as the Mullards, but it stayed tighter longer into breakup. That's the best way I can describe it. The mids were a bit more complex and broke up at about the same levels, but gave me slightly better harmonics and crunch with a little more punch. Granted, my amp was purchased used so I don't know how many hours were on the Mullards...I should've mentioned that from the start. I notice I keep using the words "slightly" and "close" because the two brands are actually pretty similar on tone to my ears. We recorded the rehearsal and I really noticed a bigger difference on the leads. Check it out, the other guitarist just retubed his 5150...he plays it through a traditional Recto 4x12, I play through a Buzzbomb 2x12...my lead tone was soooooo much better than his. On rhythm, I loved the saturation the new tubes gave me...not too much, not too little...just right.
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Post by Hacksaw on Dec 5, 2005 15:43:34 GMT -5
Wow! thats interesting! I have never ran mullards before so this is very intersting. I like the Svetlanas cause they are durable ( as far as tubes go) and sound very good. I am now running them in my jtm45 and they break up real nice. ( talk about harmonic over tones!) Thats good they are very close in sound. I cant wait to try them myself.
The used amp thing,, what you loose is the actual punch when they are older. I have ran the same tubes for years (3-5 years and no failures) and liked the lack of punch at times. really smoothed things up. ( great for softer ballad stuff).
Just curious, did you bring down the bias and see if all the tubes would bias at the same level?
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Post by craggin on Dec 5, 2005 16:17:41 GMT -5
Good point (again), no...maybe I should try that and see what happens. I don't have a 'scope so I rely on the bias rite with the "70% rule" to help me bias. The problem with that is sometimes even at 70% you still get crossover distortion in some heads. My JCM800 got it using Siemens 6CA7's until I ran the bias (a tech had a scope where we checked it) up around 80% of max plate dissipation...that was kind of stupid of me because it isn't advised to even use those tubes in amps drawing over 450v...this JCM was drawing almost 500. Running the tubes that hot was probably asking for trouble...but what the heck...it sounded GREAT!! (But stupid loud LOL!!)
...back to the Quick Rod...
I know that the general rule of thumb is to bias at around 70% of plate dissipation, and that most QR's are biased around 30mA which is around 60% of plate dissipation...so I was reluctant to bias it cooler. I probably shouldn't get too anal about that because as long as the amp sounds good, who cares where its biased as long as it isn't too hot...right? Many boutique amp builders find that their circuits sound better biased a little cooler. (and I'm not referring to Mesa's, etc.) I'll give it a try and see what happens...thanks for the tip!!!
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Post by Hacksaw on Dec 5, 2005 16:35:29 GMT -5
I have been reading a lot on tubes and biasing.. since I been building amps.. ( ok just two so far! haha) granted I am no expert, and scott splawn is the all expert !! I seen lots of refferences to biasing tubes where there is one control for all four tubes, to bring bias to where all the tubes are even matched in ma. this also depends on the tube draw within each tube. I have had afew amps that I have worked on. that ended up being like that. the original crate blue voodoo was one. bias went down to 26ma and all tubes where even. it sounded good ( for a crate with jj tubes.) the original ma draw from factory was 25. Yeaup,, I called them and asked about the proper place for bias.. they said 40ma. sounded terrible ( strange I thought) with 465v of plate. haha.. ya just never know where a amp may end up liking the bias. since there is only one bias control. the scope showed a small notch at the cross over.. but I considered that acceptable. ( sometimes they actually sound better with tad bit). interesting that some Expert guitar guys will actually bias by ear. I havent tried that yet!! hahah.. I know I would blow up something!! LOL!!
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Post by craggin on Dec 6, 2005 10:49:36 GMT -5
Hacksaw...lowering the bias did help bring the odd tube closer to the rest...but I wasn't crazy by the tone so I put it back. I have an online source that does a killer job (best I've ever seen) of matching quads...usually less than .2 mA between all of them, so I may order a quad from them and use the current tubes as backups. With the price I paid, I can easily afford to do this. (The local shop had no idea what they had and charged me a very little sum of money for the tubes...whew.)
I'm with you...I couldn't just bias by ear alone...that would be dangerous!!! LOL!!!!
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Post by jimbax on Dec 6, 2005 11:02:58 GMT -5
FWIW....when Don Butler biases my amps he scopes it and electronically biases and then plugs a guitar in and makes 'tone' adjustments...the amp never ends up where the mfg suggests the bias should be...he has good ears too...we try out different brands of tubes to hear the sonic differences...I will give up a little sound/tone for RELIABILITY...but would prefer BOTH!!!
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Post by craggin on Dec 6, 2005 11:16:07 GMT -5
...I will give up a little sound/tone for RELIABILITY...but would prefer BOTH!!! Isn't that the truth!!!
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Post by jimbax on Dec 6, 2005 11:33:20 GMT -5
Oh, BTW, I found that the QR does NOT like NOS preamp tubes (not the ones I typically like in my other amps anyway...) I tried: (12ax7 or ECC83) Mullards, JAN Philips, Valvo, and Telefunken smooth and rib..the jj12ax7s has more gain and sac in this amp...
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Post by Hacksaw on Dec 6, 2005 11:59:32 GMT -5
Running these amps at 60-70% should give both! ( I think thats where they are! wasnt that right craggin?:-) ) hey Craggin, I use Bob at www.eurotubes.com great support and very good matched JJ tubes, stands behind them. always answer emails. ( and I asked a lot!) Dunno where I am going to get mullards. nokidding jimbax? doesnt like the other preamp tubes huh.. Wow I wouldnt have thought. Thanks for that info!!
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Post by craggin on Dec 6, 2005 12:08:47 GMT -5
Hey, funny you mention the preamp tubes...I found something fairly similar. The only NOS tubes my QR liked is an RFT in V1...the JJ's really do sound awesome in it.
Hacksaw...yes, Scott sends these out biased right in between 60-70% (at least that's where mine tested).
Bob at Eurotubes is excellent as a source!!!
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Post by Hacksaw on Dec 6, 2005 12:16:21 GMT -5
I would test the bias in mine and see where the bias is, IF i could stop playing it long enough! LOL!!
you guys just saved me from time testing pre amp tubes. THANKS
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Post by craggin on Dec 9, 2005 10:56:43 GMT -5
Okay...I decided to get another quad of SED "Winged C" EL34's that were supposed to be extremely tightly matched and use the "closely matched" quad as a backup. I installed them yesterday and tested them...they were PERFECTLY matched. The Mullards that come stock are biased around 30mA, but I decided to juice the SED's a bit more and see what happens. 70% of max dissipation would be around 35mA, so I thought that would be a good starting point...WOW, the amp got warmer sounding and punchier. I decided to follow Jimbax's lead and let my ear do the walking. I didn't check the voltmeter for this experiment...I just went by my ear. When it was all said and done, it sounded better up over 33mA with these tubes. (That might not be the same with the stock Mullards.) They just seemed more complex with some really sweet, complex mids...it was like they got bigger or broader sounding.
For all you old Marshall lovers out there (and I'm one of them), if you have the old Svetlana tubes laying around from the St. Petersburg factory...they're the same tubes...throw 'em in and see what'chya think.
If anyone's interested, I tested several preamp tubes...NOS and current production. The only NOS tube I really liked in V1 was an RFT...sounded great in the OD channels, but my clean tone suffered a little bit (stress the word little). That didn't bother me too much...but if others rely on the clean...stick with the JJ's. I've got the JJecc83s and ec803 to compare..the clean channel liked the 803 the most where the JJecc83s was the best all around tube in all 3 positions. My head didn't care for the EH12ax7 in V1 at all. The Sovtek, Chinese 9th generation, and GT 7025 all sounded mediocre at best. I will say, the new Ruby 7025ss sounded pretty sweet in V1, but with the RFT in V1, the 803 in V2, and the Ruby in V3...I was really pleased. One other NOS tube worth mentioning was a Seimens...pretty nice tube. Any other NOS tubes I tried just didn't seem to do much for me.
If I didn't happen to have so many preamp tubes laying around, the JJecc83s would be THE tube I'd go to. I probably wouldn't spend the extra money NOS tubes cost for the marginal (and I mean marginal) increase in perceived tone.
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Post by jimbax on Dec 9, 2005 12:31:46 GMT -5
Okay...I decided to get another quad of SED "Winged C" EL34's that were supposed to be extremely tightly matched and use the "closely matched" quad as a backup. I installed them yesterday and tested them...they were PERFECTLY matched. The Mullards that come stock are biased around 30mA, but I decided to juice the SED's a bit more and see what happens. 70% of max dissipation would be around 35mA, so I thought that would be a good starting point...WOW, the amp got warmer sounding and punchier. I decided to follow Jimbax's lead and let my ear do the walking. I didn't check the voltmeter for this experiment...I just went by my ear. When it was all said and done, it sounded better up over 33mA with these tubes. (That might not be the same with the stock Mullards.) They just seemed more complex with some really sweet, complex mids...it was like they got bigger or broader sounding. For all you old Marshall lovers out there (and I'm one of them), if you have the old Svetlana tubes laying around from the St. Petersburg factory...they're the same tubes...throw 'em in and see what'chya think. If anyone's interested, I tested several preamp tubes...NOS and current production. The only NOS tube I really liked in V1 was an RFT...sounded great in the OD channels, but my clean tone suffered a little bit (stress the word little). That didn't bother me too much...but if others rely on the clean...stick with the JJ's. I've got the JJecc83s and ec803 to compare..the clean channel liked the 803 the most where the JJecc83s was the best all around tube in all 3 positions. My head didn't care for the EH12ax7 in V1 at all. The Sovtek, Chinese 9th generation, and GT 7025 all sounded mediocre at best. I will say, the new Ruby 7025ss sounded pretty sweet in V1, but with the RFT in V1, the 803 in V2, and the Ruby in V3...I was really pleased. One other NOS tube worth mentioning was a Seimens...pretty nice tube. Any other NOS tubes I tried just didn't seem to do much for me. If I didn't happen to have so many preamp tubes laying around, the JJecc83s would be THE tube I'd go to. I probably wouldn't spend the extra money NOS tubes cost for the marginal (and I mean marginal) increase in perceived tone. hey, on the QR which preamp tubes are which (from left te right) ?
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Post by DonaldDemon on Dec 9, 2005 12:35:32 GMT -5
I can attest to the JJ's being the best preamp tube as well. I tried a few different types of tubes but it seemed to make the tone suffer rather than help it. I really thought my NOS Philipps/Hiwatt ecc83's would sound great because they worked miracles in my Rivera but they just made my Pro Mod sound flat and took away its nutz. It just goes to show how differently voiced amps can be. I also tried some Sovtek LP's, EH12ax7, GT Mullard reissues 12ax7 (another one I thought would sound killer), and some NOS chinese ecc83's and again the JJecc83's won hands down. That's great to know because that means less money I have to spend when it comes time to change them! Hacksaw, I have also dealt with Bob at Eurotubes and he knows his stuff and is super helpful. I wouldn't go to anyone else.
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