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#1
Posted to rec.audio.tubes
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EH 7591s - Experience in favor of NOS tubes
Over a year ago I bought a quad of EH 7591As (not the repinned 6L6, but the
supposed 7591 exact replacement). I estimate that I have less than 1000 hours on the quad (installed in a Japanese receiver). The bias had been carefully set. The amp had always been run on low volumes and the plates were never red. By accident I tapped the back side of the receiver with an antenna that weighed about 1 oz. and shorted out one of the 7591s. Fortunately, it was protected by a 10 ohm cathode resistor. That gave me the "opportunity" to recheck the tubes. In addition to the cathode-shorted tube, 2 of the 4 had very low emissions - far below the 5600 minimum value stated on the Hickok 539B's roller. People on this NG claim that many of the Russian tubes are good, but my experience with too many of them has been bad. This quad of EH 7591s obviously sucks, but so have small signal Sovtek 12AX7s and the like, which seem to have incredibly reduced cathode emissions after a year or so. Some Eico (Westinghouse) 7591s that are over 40 years old are cranking right along with great emissions. Are the Svetlana Winged C series any better of the long term? Anyone else? Jon |
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#2
Posted to rec.audio.tubes
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EH 7591s - Experience in favor of NOS tubes
"Jon Yaeger" wrote in message ... Over a year ago I bought a quad of EH 7591As (not the repinned 6L6, but the supposed 7591 exact replacement). I estimate that I have less than 1000 hours on the quad (installed in a Japanese receiver). The bias had been carefully set. The amp had always been run on low volumes and the plates were never red. By accident I tapped the back side of the receiver with an antenna that weighed about 1 oz. and shorted out one of the 7591s. Fortunately, it was protected by a 10 ohm cathode resistor. That gave me the "opportunity" to recheck the tubes. In addition to the cathode-shorted tube, 2 of the 4 had very low emissions - far below the 5600 minimum value stated on the Hickok 539B's roller. People on this NG claim that many of the Russian tubes are good, but my experience with too many of them has been bad. This quad of EH 7591s obviously sucks, but so have small signal Sovtek 12AX7s and the like, which seem to have incredibly reduced cathode emissions after a year or so. Some Eico (Westinghouse) 7591s that are over 40 years old are cranking right along with great emissions. Are the Svetlana Winged C series any better of the long term? Anyone else? Jon Hi Jon, I've used SED's (6550, KT88, EL34) for quite a few years and have been very pleased. Something I wasn't with other Russian / Chinese tubes; admittedly, that was back in the mid 90's. It's not to say I haven't blown up an SED but from an emission standpoint, they were / are pretty solid. I have a set of EH 7868's from Triode Electronics in my S-8000 for about the same amount of time you stated for the EH 7591's. I may pull & test 'em to see how they are doing. I seem to recall a Glass Audio article regarding the 7591 and their short comings. According to the article, the G2 alignment of the 91's (and the 7868 I assume) is the weak point. Failures mostly due to burned G2 grid wires. I've always suspected the grid wire quality in current tubes to be less than that of good NOS, would explain a lot. SED at one time was going to make a 91 but I believe went after the triode market instead. Pity. MarkS |
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#3
Posted to rec.audio.tubes
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EH 7591s - Experience in favor of NOS tubes
Jon Yaeger said:
Over a year ago I bought a quad of EH 7591As (not the repinned 6L6, but the supposed 7591 exact replacement). I estimate that I have less than 1000 hours on the quad (installed in a Japanese receiver). The bias had been carefully set. The amp had always been run on low volumes and the plates were never red. By accident I tapped the back side of the receiver with an antenna that weighed about 1 oz. and shorted out one of the 7591s. Fortunately, it was protected by a 10 ohm cathode resistor. That gave me the "opportunity" to recheck the tubes. In addition to the cathode-shorted tube, 2 of the 4 had very low emissions - far below the 5600 minimum value stated on the Hickok 539B's roller. People on this NG claim that many of the Russian tubes are good, but my experience with too many of them has been bad. This quad of EH 7591s obviously sucks, but so have small signal Sovtek 12AX7s and the like, which seem to have incredibly reduced cathode emissions after a year or so. Some Eico (Westinghouse) 7591s that are over 40 years old are cranking right along with great emissions. Are the Svetlana Winged C series any better of the long term? Anyone else? Dunno about the EH, but I bought a quad of JJ 7591A about 2 years ago for a client with a Mac 230 amp, he uses it daily and the tubes are still as good as they were on the day I installed them. He recently asked me to check them on my AVO tester, hence the knowledge ;-) They sound good as well (plus, they fit under the hood, unlike the EHs!) Mind you, the Macs are class B designs though, so how they would perform when constantly pushed to their limits in a class A amp I couldn't tell. -- "Due knot trussed yore spell chequer two fined awl miss steaks." |
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#4
Posted to rec.audio.tubes
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EH 7591s - Experience in favor of NOS tubes
Jon Yaeger wrote:
People on this NG claim that many of the Russian tubes are good, but my experience with too many of them has been bad. This quad of EH 7591s obviously sucks, but so have small signal Sovtek 12AX7s and the like, which seem to have incredibly reduced cathode emissions after a year or so. I think you have to be careful about making generalizations about any given brand or origin of tube based on an anecdotal experience. I've seen strings of dud tubes from about any manufacturer you want to name (and, yes, I once got a box of AT&T WE300B's where 3 of them had loose pieces of glass inside). EH has sold like thousands of 7591's, so obviously they don't all suck. It was only a few years ago that there were practically no 7591's available at all, and people were crying for someone, anyone, to make some. Some Eico (Westinghouse) 7591s that are over 40 years old are cranking right along with great emissions. The age doesn't mean anything. I have a 1950 Zenith clock radio with its original tubes that works fine, but it only works for about 2 minutes per day. I'm more impressed with the Telechron clock that's 56 years old and still runs 24 hours a day. Are the Svetlana Winged C series any better of the long term? They don't make 7591's. -- Ned Carlson SW side of Chicago, USA www.tubezone.net |
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#6
Posted to rec.audio.tubes
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EH 7591s - Experience in favor of NOS tubes
Hey Jon,
I use winged C 6550's pretty much exclusively in guitar & bass amps because they're more rugged and can handle really high voltages and dissipations, and the musicians who own amps that use them know that and demand winged C's. The same musicians demand EH 12AX7's in the front end of their amps because they think they're quieter than other brands. I'm not so sure they're right about that, but I give them what they want. I have to pretest them for noise in order to have really quiet tubes for the input stages. And I don't do that for free, I charge double for 12AX7's that are tested quiet. But what I charge is still cheaper than the bull**** companies like Ruby and Groove Tubes charge for their supposedly hand tested Chinese crap. Don't get me started... ;-) If you've experienced loss of emission in EH 12AX7's, I'd suggest you check the equipment, because something is wrong and it's not the tubes. Plugging a 12AX7 into a stage meant for a 12AU7 or 12AT7 will eventually destroy the tube, because it's not designed to handle the much higher current the AU and AT are built for. EH tubes may become noisy or microphonic over time - in guitar amps, they are subject to a lot of physical abuse from vibration, but they do not lose their emission in a properly working circuit. And Sovtec/EH tubes last as long as anyone else's, IME. For amps designed for 5881's or EL34's, Sovtec/EH tubes work just fine. And I've found their matched tube sets to actually be and stay matched over the last few years. That's a distinct improvement compared to the old days... Lord Valve is a good resource regarding which tubes work best in which guitar & bass amps, and why. You can find him over at Alt.Guitar.Amps. Sign up to be spammed by him and he'll email you a very informative set of catalogs every few months. He'd probably appreciate it if you bought a tube or few from him. I have, and have also referred some of my customers to him for help when they're on the road. No complaints so far, but YMMV. Regards, Fred "Jon Yaeger" wrote in message ... in article , Ned Carlson at wrote on 10/28/06 3:26 AM: Jon Yaeger wrote: People on this NG claim that many of the Russian tubes are good, but my experience with too many of them has been bad. This quad of EH 7591s obviously sucks, but so have small signal Sovtek 12AX7s and the like, which seem to have incredibly reduced cathode emissions after a year or so. I think you have to be careful about making generalizations about any given brand or origin of tube based on an anecdotal experience. *** Of course, you are (logically) correct. However, I am not going to continue to make a personal investment in these tubes to find out if others they have made are good. *** I was trying to do an informal survey to see what other's "anecdotal" experiences with Russian tubes were like. You don't mention YOUR experience in your reply. Too bad - I respect your opinion. I've seen strings of dud tubes from about any manufacturer you want to name (and, yes, I once got a box of AT&T WE300B's where 3 of them had loose pieces of glass inside). *** No doubt. EH has sold like thousands of 7591's, so obviously they don't all suck. *** This is not necessarily true. Quantity sold does not equate to quality, especially if it takes a period of time for the problem(s) to surface. It was only a few years ago that there were practically no 7591's available at all, and people were crying for someone, anyone, to make some. *** Agreed. Some Eico (Westinghouse) 7591s that are over 40 years old are cranking right along with great emissions. The age doesn't mean anything. I have a 1950 Zenith clock radio with its original tubes that works fine, but it only works for about 2 minutes per day. I'm more impressed with the Telechron clock that's 56 years old and still runs 24 hours a day. *** Point well taken. Let me pose an unrelated question, Ned. How much tube gear do you own that you use frequently, and what brands of tubes do you use? Are the Svetlana Winged C series any better of the long term? They don't make 7591's. *** I know. I was considering the Svets for a different project and wanted to see if anyone had any long-term experience with them. Cheers & best regards, Jon |
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#7
Posted to rec.audio.tubes
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EH 7591s - Experience in favor of NOS tubes
Phread wrote: Hey Jon, I use winged C 6550's pretty much exclusively in guitar & bass amps because they're more rugged and can handle really high voltages and dissipations, and the musicians who own amps that use them know that and demand winged C's. The same musicians demand EH 12AX7's in the front end of their amps because they think they're quieter than other brands. I'm not so sure they're right about that, but I give them what they want. I have to pretest them for noise in order to have really quiet tubes for the input stages. And I don't do that for free, I charge double for 12AX7's that are tested quiet. But what I charge is still cheaper than the bull**** companies like Ruby and Groove Tubes charge for their supposedly hand tested Chinese crap. Don't get me started... ;-) If you've experienced loss of emission in EH 12AX7's, I'd suggest you check the equipment, because something is wrong and it's not the tubes. Plugging a 12AX7 into a stage meant for a 12AU7 or 12AT7 will eventually destroy the tube, because it's not designed to handle the much higher current the AU and AT are built for. EH tubes may become noisy or microphonic over time - in guitar amps, they are subject to a lot of physical abuse from vibration, but they do not lose their emission in a properly working circuit. And Sovtec/EH tubes last as long as anyone else's, IME. For amps designed for 5881's or EL34's, Sovtec/EH tubes work just fine. And I've found their matched tube sets to actually be and stay matched over the last few years. That's a distinct improvement compared to the old days... Lord Valve is a good resource regarding which tubes work best in which guitar & bass amps, and why. You can find him over at Alt.Guitar.Amps. Sign up to be spammed by him and he'll email you a very informative set of catalogs every few months. He'd probably appreciate it if you bought a tube or few from him. I have, and have also referred some of my customers to him for help when they're on the road. No complaints so far, but YMMV. Regards, Fred Hey, thanks for the plug. I don't post to alt.guitar.amps any more - it's turned into a complete sea of leftist homosexual filth. If you want to read about penises and feces, AGA is the place to go. For guitar amps, I don't know where to send ya. Try e-mailing me. ;-) Lord Valve Expert VISIT MY WEBSITE: http://www.nebsnow.com/LordValve I specialize in top quality HAND SELECTED NOS and current-production vacuum tubes for guitar and bass amps. Good prices, fast service. Authorized dealer for QSC amps, Sovtek/Electro-Harmonix, Behringer, Hammond-Suzuki, Leslie, Rolls, Weber VST, etc.! - Partial Client List - * Derek Trucks (Allman Brothers Band/Derek Trucks Band) * * Meatloaf * Catherine Wheel * Yo La Tengo * Let's Go Bowling * * Kofi Burbridge (DTB) * Tod Smallie (DTB) * Susan Tedeschi * * Roy Pritts (former head, Audio Engineering Society) * * Rob Hyckys (guitarist for Commander Cody) * Waky Amps * * Jamie McLean (guitarist for the Dirty Dozen Brass Band) * * John Pierce (bassist for Huey Lewis and the News) * * Rob Eaton (guitarist for Dark Star Orchestra) * * Detroit Frank DuMont (guitarist, Frank DuMont and the Drivin' Wheels) * * Coco Montoya * Clint Black * Bill McKay * Mojo Watson * Dick Dale * * Fleetwood Mac * Tyrin Benoit * Eugene Fodor * Dale Bruning * * Komet Amplification * Dr. Z * Maven Peal * Blockhead Amps * * Jim Kelley * Balls Amplification * Roccaforte Amplifiers * * Gerhart Amplification * Aiken Amplification * Germino Amplification * * Lots More * NBS Electronics, 230 South Broadway, Denver, CO 80209-1510 Phone orders/tech support after 1:30 PM Denver time at 303-778-1156 - Our 25th Year - VISA - MASTERCARD - PAYPAL - DISCOVER "It ain't braggin', if ya can do it." - Dizzy Dean |
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#8
Posted to rec.audio.tubes
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EH 7591s - Experience in favor of NOS tubes - Thanks, Fred
in article , Phread at
wrote on 10/28/06 11:07 PM: Hey Jon, I use winged C 6550's pretty much exclusively in guitar & bass amps because they're more rugged and can handle really high voltages and dissipations, and the musicians who own amps that use them know that and demand winged C's. The same musicians demand EH 12AX7's in the front end of their amps because they think they're quieter than other brands. I'm not so sure they're right about that, but I give them what they want. I have to pretest them for noise in order to have really quiet tubes for the input stages. And I don't do that for free, I charge double for 12AX7's that are tested quiet. But what I charge is still cheaper than the bull**** companies like Ruby and Groove Tubes charge for their supposedly hand tested Chinese crap. Don't get me started... ;-) If you've experienced loss of emission in EH 12AX7's, I'd suggest you check the equipment, because something is wrong and it's not the tubes. Plugging a 12AX7 into a stage meant for a 12AU7 or 12AT7 will eventually destroy the tube, because it's not designed to handle the much higher current the AU and AT are built for. EH tubes may become noisy or microphonic over time - in guitar amps, they are subject to a lot of physical abuse from vibration, but they do not lose their emission in a properly working circuit. And Sovtec/EH tubes last as long as anyone else's, IME. For amps designed for 5881's or EL34's, Sovtec/EH tubes work just fine. And I've found their matched tube sets to actually be and stay matched over the last few years. That's a distinct improvement compared to the old days... Lord Valve is a good resource regarding which tubes work best in which guitar & bass amps, and why. You can find him over at Alt.Guitar.Amps. Sign up to be spammed by him and he'll email you a very informative set of catalogs every few months. He'd probably appreciate it if you bought a tube or few from him. I have, and have also referred some of my customers to him for help when they're on the road. No complaints so far, but YMMV. Regards, Fred "Jon Yaeger" wrote in message ... in article , Ned Carlson at wrote on 10/28/06 3:26 AM: Jon Yaeger wrote: People on this NG claim that many of the Russian tubes are good, but my experience with too many of them has been bad. This quad of EH 7591s obviously sucks, but so have small signal Sovtek 12AX7s and the like, which seem to have incredibly reduced cathode emissions after a year or so. I think you have to be careful about making generalizations about any given brand or origin of tube based on an anecdotal experience. *** Of course, you are (logically) correct. However, I am not going to continue to make a personal investment in these tubes to find out if others they have made are good. *** I was trying to do an informal survey to see what other's "anecdotal" experiences with Russian tubes were like. You don't mention YOUR experience in your reply. Too bad - I respect your opinion. I've seen strings of dud tubes from about any manufacturer you want to name (and, yes, I once got a box of AT&T WE300B's where 3 of them had loose pieces of glass inside). *** No doubt. EH has sold like thousands of 7591's, so obviously they don't all suck. *** This is not necessarily true. Quantity sold does not equate to quality, especially if it takes a period of time for the problem(s) to surface. It was only a few years ago that there were practically no 7591's available at all, and people were crying for someone, anyone, to make some. *** Agreed. Some Eico (Westinghouse) 7591s that are over 40 years old are cranking right along with great emissions. The age doesn't mean anything. I have a 1950 Zenith clock radio with its original tubes that works fine, but it only works for about 2 minutes per day. I'm more impressed with the Telechron clock that's 56 years old and still runs 24 hours a day. *** Point well taken. Let me pose an unrelated question, Ned. How much tube gear do you own that you use frequently, and what brands of tubes do you use? Are the Svetlana Winged C series any better of the long term? They don't make 7591's. *** I know. I was considering the Svets for a different project and wanted to see if anyone had any long-term experience with them. Cheers & best regards, Jon Fred, Thanks for your helpful reply. Jon |
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#9
Posted to rec.audio.tubes
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EH 7591s - Experience in favor of NOS tubes
Jon Yaeger wrote:
*** I was trying to do an informal survey to see what other's "anecdotal" experiences with Russian tubes were like. You don't mention YOUR experience in your reply. Too bad - I respect your opinion. I've sold quite a few and the return/complaint rate was not out of line, if it was, I would've quit selling them. I quit selling other tubes when I got too many complaints, eg: I quit selling JJ KT88's, but apparently they've fixed their quality control problems since then. Note that many complaints , like yours , turn up when the tubes are way out of warranty, but I hear about it nonetheless. I would say that the JJ 7591 test hotter than the EH, and it's nice that they have a smaller bulb, but people have had problems with those too. (they may be fine, now, that was a while ago) Like any new models of anything, it may take awhile to work the bugs out, and keeping up quality control on high Gm output tubes is a bitch. US companies had problems with both 7591 and 8417, this is not just a Russian or Slovak problem. Still, I have to point out that anecdotes ain't statistics until you accumulate a big bunch of them. It's way too easy for one person's one-off experience to get spread around and color the opinions of lots of people even if the statistical evidence doesn't back up the negative publicity. *** This is not necessarily true. Quantity sold does not equate to quality, especially if it takes a period of time for the problem(s) to surface. Returns cost money. Lots of money. Every returned dud tube wipes out the profit on ten good ones. If even 10% of those tubes were duds, even after 1000 hours, somebody would be raising hell about it. *** Point well taken. Let me pose an unrelated question, Ned. How much tube gear do you own that you use frequently, and what brands of tubes do you use? Well, other than my clock radio, I've been using my $99 homebrew SE 5 watt/channel a lot. I also own a Sherwood S5000-II and a Dynaco ST35. Frankly, I don't pay a lot of attention to what brands of tubes I put in my stuff, so long as they work OK, usually I get tubes from inventory I can't sell, like tubes with glass rattles. People who design tube gear should assume that the enduser is going to plug in whatever crap they have lying around, back in the bad old days, people used to pick their tubes from whatever was in the bin under the tube tester at Walgreens. -- Ned Carlson SW side of Chicago, USA www.tubezone.net |
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#10
Posted to rec.audio.tubes
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EH 7591s - Experience in favor of NOS tubes
I've sent you (3) e-mails asking for price / availability on the Svets, but
have yet to receive the benefit or courtesy of a reply. Guess you must be really busy, or just not that interested in selling tubes. Jon From: Lord Valve Organization: EarthLink Inc. -- http://www.EarthLink.net Newsgroups: rec.audio.tubes Date: Sun, 29 Oct 2006 13:09:15 GMT Subject: EH 7591s - Experience in favor of NOS tubes Hey, thanks for the plug. I don't post to alt.guitar.amps any more - it's turned into a complete sea of leftist homosexual filth. If you want to read about penises and feces, AGA is the place to go. For guitar amps, I don't know where to send ya. Try e-mailing me. ;-) Lord Valve Expert |
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#11
Posted to rec.audio.tubes
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EH 7591s - Experience in favor of NOS tubes
Lord Valve wrote: Phread wrote: Hey Jon, I use winged C 6550's pretty much exclusively in guitar & bass amps because they're more rugged and can handle really high voltages and dissipations, and the musicians who own amps that use them know that and demand winged C's. The same musicians demand EH 12AX7's in the front end of their amps because they think they're quieter than other brands. I'm not so sure they're right about that, but I give them what they want. I have to pretest them for noise in order to have really quiet tubes for the input stages. And I don't do that for free, I charge double for 12AX7's that are tested quiet. But what I charge is still cheaper than the bull**** companies like Ruby and Groove Tubes charge for their supposedly hand tested Chinese crap. Don't get me started... ;-) If you've experienced loss of emission in EH 12AX7's, I'd suggest you check the equipment, because something is wrong and it's not the tubes. Plugging a 12AX7 into a stage meant for a 12AU7 or 12AT7 will eventually destroy the tube, because it's not designed to handle the much higher current the AU and AT are built for. EH tubes may become noisy or microphonic over time - in guitar amps, they are subject to a lot of physical abuse from vibration, but they do not lose their emission in a properly working circuit. And Sovtec/EH tubes last as long as anyone else's, IME. For amps designed for 5881's or EL34's, Sovtec/EH tubes work just fine. And I've found their matched tube sets to actually be and stay matched over the last few years. That's a distinct improvement compared to the old days... Lord Valve is a good resource regarding which tubes work best in which guitar & bass amps, and why. You can find him over at Alt.Guitar.Amps. Sign up to be spammed by him and he'll email you a very informative set of catalogs every few months. He'd probably appreciate it if you bought a tube or few from him. I have, and have also referred some of my customers to him for help when they're on the road. No complaints so far, but YMMV. Regards, Fred Hey, thanks for the plug. I don't post to alt.guitar.amps any more - it's turned into a complete sea of leftist homosexual filth. You're talking about Claudette. But he's a right-winger. If you want to read about penises and feces That pretty much sums up your sex life, doesn't it, Willie? You lost, Willie. GET OVER IT!  --E |
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