more info on my new Univox head
Question:
I have a list of the tubes in my new/old Univox amp head I recently bought on ebay. I’m in hopes someone more knowlegeable than I can give me an idea what the wattage on this head would be. The seller thought it to be a 30 watter, but if its athe U-1221 head I think it is, an old Univox catalog says it is a 50 watter. The head sounds fantastic, but seems much lower in power than these figures would indicate. My Blues Junior seems more powerful. I don’t think its the speaker cab I got with it-it has two ten incj Jensens, and old ones at that, since the cab is a converted old Univov combo amp. Now I removed the back of the amp, and sure enough, when I got some good lighting in there, the tube numbers are stamped in the metal frame the tubes mount on. Here are yhe numers from left to right: 7591, 7591, 12AX7, 12AU7, 12AX7, 6AN8, 12AX7, for a total of seven tubes. Now this amp has both reverb and tremolo, so I don’t know if a tube or two might be used to power them or not? I may take it to my friend for retubing, but due to a $600.00 vet bill on my adopted ex-racing Greyhound, it may be a few weeks. Thanks for any comments on this great sounding amp. Jon Neet
Response:
– Hide quoted text — Show quoted text -> I have a list of the tubes in my new/old Univox amp head I recently >bought on ebay. I’m in hopes someone more knowlegeable than I can give >me an idea what the wattage on this head would be. The seller thought >it to be a 30 watter, but if its athe U-1221 head I think it is, an old >Univox catalog says it is a 50 watter. The head sounds fantastic, but >seems much lower in power than these figures would indicate. My Blues >Junior seems more powerful. I don’t think its the speaker cab I got >with it-it has two ten incj Jensens, and old ones at that, since the >cab is a converted old Univov combo amp. > Now I removed the back of the amp, and sure enough, when I got some >good lighting in there, the tube numbers are stamped in the metal frame >the tubes mount on. Here are yhe numers from left to right: 7591, 7591, >12AX7, 12AU7, 12AX7, 6AN8, 12AX7, for a total of seven tubes. Now this >amp has both reverb and tremolo, so I don’t know if a tube or two might >be used to power them or not? > I may take it to my friend for retubing, but due to a $600.00 vet >bill on my adopted ex-racing Greyhound, it may be a few weeks. > Thanks for any comments on this great sounding amp. > Jon Neet
Congrats on the amp and best wishes for the Greyhound. I assume you’ve been to http://www.univox.org/amps/uniamp.html to gather what info they have, and been to http://forums.univox.org/forum.asp?FORUM_ID=3 … to post any questions you might have? Got pics? -Scott McKnight
Response:
- Hide quoted text — Show quoted text – > I have a list of the tubes in my new/old Univox amp head I recently > bought on ebay. I’m in hopes someone more knowlegeable than I can give > me an idea what the wattage on this head would be. The seller thought > it to be a 30 watter, but if its athe U-1221 head I think it is, an old > Univox catalog says it is a 50 watter. The head sounds fantastic, but > seems much lower in power than these figures would indicate. My Blues > Junior seems more powerful. I don’t think its the speaker cab I got > with it-it has two ten incj Jensens, and old ones at that, since the > cab is a converted old Univov combo amp. > Now I removed the back of the amp, and sure enough, when I got some > good lighting in there, the tube numbers are stamped in the metal frame > the tubes mount on. Here are yhe numers from left to right: 7591, 7591, > 12AX7, 12AU7, 12AX7, 6AN8, 12AX7, for a total of seven tubes. Now this > amp has both reverb and tremolo, so I don’t know if a tube or two might > be used to power them or not? > I may take it to my friend for retubing, but due to a $600.00 vet > bill on my adopted ex-racing Greyhound, it may be a few weeks. > Thanks for any comments on this great sounding amp. > Jon Neet
Jon, I haven’t checked Tim Patton’s Univox site, but I doubt they were pushing 50 watts from a pair of 7591 power tubes. 25-35 watts is more likely for those. Nice sounding tubes though, when running right. I’d think it should be *at least* on par with the BJ volume- wise. Perhaps the power tubes have many playing hours on them and are tired? Try it with the BJ speaker, or the BJ with the Univox cab for a more fair comparison of the two. I suspect the 50 watt model that you reference is a 2-6L6 version. Also, some amp designs run the whole preamp signal in series thorough the reverb and trem circuitry, instead of as a parallel circuit; and it causes considerable loss of tone and gain. I’m not saying yours is like that, but I found that case in an old Sunn Solarus head, and rigged in a bypass switch around the reverb/trem circuit for lead playing. The amp came alive!!! Anyways, despite some folks opinion that the Japanese parts and construction technique in the Univox amps is not the best, I’ve heard them set up to sound really great! Good luck with the amp and the Greyhound. Regards, John King
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Thanks for the replys. I have been to the Univox website, and thats where I think I id’d my amp-in one of the old catalogs.At least, I found a head that looks just like mine with all the controls and inputs line up exactly the sameIn that catalog they stated that that particular amp was 50 watts.But I also remember reading somewhere that some of the old amp makers wouldn’t give the power rating in watts rms, but in "music power" (or some such), which translated to less power than the more standandized watts rms rating(?). I suppose theres the possibility that there is an impedance miss match between m head and cabinet also, since, as I think I stated above, the cab is a converted old Univox combo with two tens. I might add that this cabinet is light as a feather and sounds rell nice. I’ve tried it with a couple of other amps, and it aleays improved the sound. There is a vibration, but I traced it to some loose rivets that mount the handle. The main thing is everything on the amp works, and I like the sound. Jon
Response:
– Hide quoted text — Show quoted text -> I have a list of the tubes in my new/old Univox amp head I recently >bought on ebay. I’m in hopes someone more knowlegeable than I can give >me an idea what the wattage on this head would be. The seller thought >it to be a 30 watter, but if its athe U-1221 head I think it is, an old >Univox catalog says it is a 50 watter. The head sounds fantastic, but >seems much lower in power than these figures would indicate. My Blues >Junior seems more powerful. I don’t think its the speaker cab I got >with it-it has two ten incj Jensens, and old ones at that, since the >cab is a converted old Univov combo amp. > Now I removed the back of the amp, and sure enough, when I got some >good lighting in there, the tube numbers are stamped in the metal frame >the tubes mount on. Here are yhe numers from left to right: 7591, 7591, >12AX7, 12AU7, 12AX7, 6AN8, 12AX7, for a total of seven tubes. Now this >amp has both reverb and tremolo, so I don’t know if a tube or two might >be used to power them or not? > I may take it to my friend for retubing, but due to a $600.00 vet >bill on my adopted ex-racing Greyhound, it may be a few weeks. > Thanks for any comments on this great sounding amp. > Jon Neet
Hi Jon, Congrats on the Univox. A U4100b was my first amp. According to this: http://www.freeinfosociety.com/electronics/schematics/audio/univox122… it’s supposed to have 6L6CGs in it. You’re sure they’re not 7581s? Good luck with the hound. -DC
Response:
>Jon, I haven’t checked Tim Patton’s Univox site, but I doubt they >were pushing 50 watts from a pair of 7591 power tubes. 25-35 watts >is more likely for those.
http://tdsl.duncanamps.com/show.php?des=7591A 45w AB1 different basing. That said, I also have a 2 X 7868 amp (McGohan) that’s 20W. They are good sounding tubes, but his amp is supposed to have 6L6GCs in it, by the looks of things (see my re: to the OP). I don’t recall Univox using the 7591, but I may be wrong. -DC
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Your comment about an impedance mismatch got me thinking. Uni’s typically had multiple taps on the xformer. Once you’ve retubed and checked the wiring, that should be next. How are the speakers wired -series or parallel? Are you getting 4 ohms or 16 ohms? You can rewire to the tranny for either, and it’s easy to do. Also, check the schematics on the Univox site for the original tube complement. I forget exactly where it is, but there’s a pretty good set of drawings for most of their amps somewhere on the site. Hope the dog is OK. We spend WAY too much on our pets too. Chuck
Response:
Your comment about an impedance mismatch got me thinking. Uni’s typically had multiple taps on the xformer. Once you’ve retubed and checked the wiring, that should be next. How are the speakers wired -series or parallel? Are you getting 4 ohms or 16 ohms? You can rewire to the tranny for either, and it’s easy to do. Also, check the schematics on the Univox site for the original tube complement. I forget exactly where it is, but there’s a pretty good set of drawings for most of their amps somewhere on the site. Chuck
Response:
John King, tied to the tracks, said: … > Jon, I haven’t checked Tim Patton’s Univox site, but I doubt they > were pushing 50 watts from a pair of 7591 power tubes. 25-35 watts > is more likely for those.
RCA shows anywhere from 25 to 45 watts, depending on the circuit parameters. AT 1% – 2% distortion. With higher distortion, they should easily put out over 50 watts in the right circuit. SO either number (30 or 50) seems quite possible to me. Then again, I haven’t messed with these tubes. I’m just going by the book. 8^/ > Nice sounding tubes though, when running > right. I’d think it should be *at least* on par with the BJ volume- > wise. Perhaps the power tubes have many playing hours on them and > are tired? Try it with the BJ speaker, or the BJ with the Univox > cab for a more fair comparison of the two.
Agreed. -Miles
Response:
- Hide quoted text — Show quoted text ->Jon, I haven’t checked Tim Patton’s Univox site, but I doubt they >were pushing 50 watts from a pair of 7591 power tubes. 25-35 watts >is more likely for those. > http://tdsl.duncanamps.com/show.php?des=7591A > 45w AB1 > different basing. That said, I also have a 2 X 7868 amp (McGohan) > that’s 20W. They are good sounding tubes, but his amp is supposed to > have 6L6GCs in it, by the looks of things (see my re: to the OP). I > don’t recall Univox using the 7591, but I may be wrong. > -DC
I know that a pair of 7591 is *capable* of more than the 25-35 watts I suggested, but I also still stand by my statement: "25-35 watts is more likely for those." That is my experience with 7591 powered *guitar amps*. Same as a pair of 6L6 tubes which can be pushed to 65+ watts, yet are typically run at lower power; often in the 35-50 watt range. Like you, I don’t specifically recall a 7591 head amp in the Univox line, but I do know that they had 2x 6L6 and 4x 6L6 heads that were pretty common. I seem to recall that some of their combo amps used an unusual tube compliment. John King
Response:
John King, tied to the tracks, said: … > Same as a pair of 6L6 tubes which can be pushed to 65+ watts, > yet are typically run at lower power; often in the 35-50 > watt range.
Typical except for Peavey, who loved to push them to 65 watts per pair. Did MusicMan make 6L6 amps?
Response:
>Your comment about an impedance mismatch got me thinking. Uni’s >typically had multiple taps on the xformer. Once you’ve retubed and >checked the wiring, that should be next. How are the speakers wired >-series or parallel? Are you getting 4 ohms or 16 ohms? You can rewire >to the tranny for either, and it’s easy to do. Also, check the >schematics on the Univox site for the original tube complement. I >forget exactly where it is, but there’s a pretty good set of drawings >for most of their amps somewhere on the site. Hope the dog is OK. We >spend WAY too much on our pets too. >Chuck
The schem for this one says 16 ohm output with an unused 8 ohm tap. -DC
Response:
>John King, tied to the tracks, said: >… > Same as a pair of 6L6 tubes which can be pushed to 65+ watts, > yet are typically run at lower power; often in the 35-50 > watt range. >Typical except for Peavey, who loved to push them >to 65 watts per pair. >Did MusicMan make 6L6 amps?
Yes, I believe so. Mine had 6CA7s, but toward the end they were using 6L6s, too. -DC
Response:
> John King, tied to the tracks, said: > … >Same as a pair of 6L6 tubes which can be pushed to 65+ watts, >yet are typically run at lower power; often in the 35-50 >watt range. > Typical except for Peavey, who loved to push them > to 65 watts per pair. > Did MusicMan make 6L6 amps?
Yup, I’ve had Peavey amps that made 50 watts and/or 65 watts from a pair of 6L6 power tubes (Classic hybrid, and Encore all-tube respectively). I’ve also got that old 1950s Gibson GA-77 that only makes about 25-30 watts from its pair of 6L6… And I’ve liked every one for different reasons. Kind of strange, but the later 1980s Classic hybrid had considerable clean headroom before breakup, the old 1970s Classic broke up fairly early. The Encore doesn’t seem to have a great deal of headroom considering its power rating. And of course, the old Gibson’s specialty is the sag laden, overdriven ‘brown’ sound. Bright and clean just isn’t it’s thing at all. Having had many amps that got such different sounds from a pair of 6L6 tubes is what made me realize a long time ago; that, while certain tubes may lean towards a particular tone, the surrounding circuits can affect the output dramatically. IOW, there is no *one* 6L6 (or any other tube) "sound" etched in stone. John King
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I don’t know about numbers manufactured but in real life experience I’ve seen as many 7591 Univoxes as any other power tube. -Scott
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"I suppose theres the possibility that there is an impedance miss match between m head and cabinet also, since, as I think I stated above, the cab is a converted old Univox combo with two tens." …Or that there’s something that needs fixin’. Needs a cap job maybe? "I might add that this cabinet is light as a feather and sounds rell nice. I’ve tried it with a couple of other amps, and it aleays improved the sound." I’ll bet you’re diggin’ on the sound of the old Jensens. -Scott
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Yes, I’m loving the cabinet with the old Jensen speakers. I’ve tried several other amps I have, and that cabinet improved the sound in every case. The reason I’ve been thinking the head isn’t getting full power is that in my bedroom, where I do most of my playing, I can turn in all the way up without blowing my eardrums out.Many people have said that even a 30 watt tube amp, is way louder than a 30 watt ss amp. A Peavey Classic 30 is known to be very loud, ands a Blues Junior is way loud for a 15 watt amp.My Blues Junior does seem more potent, but I’ll have to play them side by side I guess to really be sure. I stopped by Guitar Center yesterday, as I had some time on my hands, and tried out the new Epiphone Valve Junior, and the other 5 watt all tube amp. These amps are quite good for $119.00, ands $220.00 respectiveley. I hooked up my Electar Tube 10 to my Univox 2×10 cabinet, and it really came alive.The Tube 10, and the more exspensive Epiphone 5 watter, by the way, both have a standby switch. Jon Neet
Response:
> The schem for this one says 16 ohm output with an unused 8 ohm tap. > -DC
There ya go -if he’s running the amp at 16 and the speakers at 4, it might sound kinda grim. Chuck
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> I don’t know about numbers manufactured but in real life experience > I’ve seen as many 7591 Univoxes as any other power tube. > -Scott
Combo amps I presume? I haven’t watched them a great deal. Last one I really looked at was on a trip to Joplin Mo. "See" them on eBay all the time, of course, but not much around here for some reason. John King
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- Hide quoted text — Show quoted text – > Yes, I’m loving the cabinet with the old Jensen speakers. I’ve tried > several other amps I have, and that cabinet improved the sound in every > case. > The reason I’ve been thinking the head isn’t getting full power is > that in my bedroom, where I do most of my playing, I can turn in all > the way up without blowing my eardrums out.Many people have said that > even a 30 watt tube amp, is way louder than a 30 watt ss amp. A Peavey > Classic 30 is known to be very loud, ands a Blues Junior is way loud > for a 15 watt amp.My Blues Junior does seem more potent, but I’ll have > to play them side by side I guess to really be sure. > I stopped by Guitar Center yesterday, as I had some time on my > hands, and tried out the new Epiphone Valve Junior, and the other 5 > watt all tube amp. These amps are quite good for $119.00, ands $220.00 > respectiveley. I hooked up my Electar Tube 10 to my Univox 2×10 > cabinet, and it really came alive.The Tube 10, and the more exspensive > Epiphone 5 watter, by the way, both have a standby switch. > Jon Neet
I have a bit of preference for the tone of some old Jensen speakers. I’d like very much to demo some of those new Epiphone amps too. And the new Gibson GA-20 and GA-40, when they show up in local showrooms: http://gibson.com/Products/Amplifiers/Gibson%20Amplifiers/ John King
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>> I don’t know about numbers manufactured but in real life experience > I’ve seen as many 7591 Univoxes as any other power tube. > -Scott >Combo amps I presume?
The ones that I’ve seen in person have mostly been combos, though I know they made one head that matches the description of the OP’s amp. FWIW I have a Lafayette (Univox) bass amp – 2×6L6 head with a 1×15" cab (Jensen C15N). Sounds pretty good pushed by a Blues Driver. -Scott
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