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Topic: Fender Twin Reverb "Ultraliner" transformer ?'s |
Brandon Schafer
From:
Indiana, USA
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Posted 7 Mar 2013 3:30 pm |
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Hello! Has anyone out there had great luck with using a Fender Twin Reverb with the ultralinear transformer for pedal steel? I just got one for a really low price. I've got visions of putting it in a head box and using it with an 8 ohm JBL K130. But, I know that Twin Reverbs usually are looking for a 4 ohm load. I've heard rumors that the "external speaker" jack accesses an 8 ohm tap on the ultralinear models. But, I have no idea if this is true or not. Honestly, it seems counterintuitive when Twins start out with a 4 ohm load. But, maybe you amp gurus can help me out with some info.
If anyone out there has had success with this formula, let me know or chime in if you more technically minded folk have any insight! Thanks!!! |
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Tim Marcus
From:
San Francisco, CA
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Posted 7 Mar 2013 3:49 pm
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if its this one:
http://www.thevintagesound.com/ffg/schem/twin_reverb_sf_135_schem.jpg
there is only the 4 ohm tap shown.
I used to have one of these - and it only had a 4ohm output.
The ultralinear Twin is a beast of an amp - it is very loud, very clean, and burns through tubes like none other. I think it sounds great with steel.
Also, I am not sure what the power rating of that JBL is. You may want to check on that. The Twin has 135W !! It will absolutely destroy a 75W JBL speaker.
A Twin from the 60's, was 85W and could match that JBL speaker better. Its worth taking a look at it.
If you add in a screen supply, and re-wire the amp to be 85W and not ultralinear anymore you can probably get away with that JBL if in fact it is rated under 135W
hope that helps you out
_________________
Milkmansound.com |
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Bill A. Moore
From:
Silver City, New Mexico, USA
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Brandon Schafer
From:
Indiana, USA
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Posted 7 Mar 2013 4:03 pm
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Great! Well, the K130 is a 125 watt speaker as I remember it. Mine is a fresh recone, so I'm not too frightened by the power the UL delivers.
I don't think I understand how you wire the screen supply to make the UL transformer version to be an "old school" 85 watter. But, maybe my local tech might know how to do it. I already am going to have him remove the master volume from the circuit.
Since the Vibrosonic was built on the same chassis and used an 8 ohm speaker, I was hoping there'd be a good way to make this amp happy with an 8 ohm load. I was guessing Fender wouldn't bother to put a different transformer in such a low sales volume amp as the Vibosonic when so many Twin chassis were bound to be floating around the factory.
Wish I had the cake for a Milkman, Tim. Maybe someday. But, this is going to have to be my tube amp "fix" for my steel for now. I really have high hopes for getting a respectable sound out of it.  |
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Tim Marcus
From:
San Francisco, CA
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Posted 7 Mar 2013 4:03 pm
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right - if you look at where it says "vibrosonic only" it shows how to wire it as 8R
missed that
you want to check the power rating of the speaker first
also, the SICA Neo speaker comes in either 4 or 8 ohms, and can candle 250W in case you need to go there
you will get a great sound out of that amp! That was my main gigging amp before I started building Milkman amps - big low end, deep reverb - and LOUD 
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Milkmansound.com |
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Brandon Schafer
From:
Indiana, USA
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Posted 7 Mar 2013 4:08 pm
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| Tim, do you think this amp would "eat" less tubes if it was wired up to take 6550's? Or is that just crazy talk and too much investment into a amp not worth a whole lot? |
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Tim Marcus
From:
San Francisco, CA
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Posted 7 Mar 2013 8:24 pm
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I think the ultralinear output is tough on 6L6s. Not sure how 6550s would take it because I never tried them.
The 500V plate voltage would certainly suit a pair of 6550 tubes - however, you would need to at least update the bias supply to compensate for them. As is, the bias supply has a "balancing" adjustment - but what you really want is a bias voltage adjustment like the old 60's Fenders had. That will allow you to bias the output tubes properly and will reduce consumption of either tube type.
Mine ate tubes because it was squeezing a lot of power from tubes which were running very cold. When I changed the bias supply it sounded a lot better - I never got around to changing it to normal output. I sold it to a friend of mine after gutting it and turning it into a bass amp. Its now a bass amp up in seattle and kicking ass to this day.
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Milkmansound.com |
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James Morehead
From:
Prague, Oklahoma, USA - R.I.P.
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Posted 7 Mar 2013 9:08 pm
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I've run the ultralinear twin as well as the vibrosonic ultralinear. Neither did not "eat" tubes--infact, I never had a tube failure period. But as Tim indicates, those amps were biased cold. Warm them up, and those amps came alive. I also always use the old Jan Philips ^L^ GC tubes, never the new "throw-away junk tubes" that you get today. I maybe was lucky, but really, if they are set up, serviced and biased right, they are rock solid amps.
Also JBL speakers are not created equal. K series are more robust that D-F series, which were more robust than D series--all alnicos. The K 130-8, sometimes labeled "D130F with black frame and orange magnet" was one of the stock peakers used in the Vibrosonic. Steel players, by the way they use the power for sustain, did well with the JBL K130(D130F).
If you use a single K130-8 with your twin, you will lose maybe 30% power and will not harm the amp or the speaker, and you will likely not hear the difference. And with a 135w Twin, you should still have all the volume you need. I play through a 100w twinand have never wished for more power.
There is a difference with the extension speaker jack in an ultralinear amp that is different than the earlier 100w or 85 w Twins. Do your research about that, before you leap.
I loved the power and tone of the ultralinear amps, but I didn't like the reverb circuit as well as I did the 100 watt twins--they seemed more lush and warmer to me.
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"Good judgement comes from experience, and a lot of that comes from bad judgement"~old cowboy proverb.
shobud@windstream.net |
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Stephen Cowell
From:
Round Rock, Texas, USA
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Posted 7 Mar 2013 9:46 pm
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The only way to know about the transformer taps is to open the amp and look... I have a PA135, the schem shows only one tap, but inside it has both. Frankly I don't trust the funky jack-switching scheme so I'll be converting it to bring both taps out the output jacks, one four, one eight.
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New FB Page: Lap Steel Licks And Stuff: https://www.facebook.com/groups/195394851800329 |
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Gary Lee Gimble
From:
Fredericksburg, VA.
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Brandon Schafer
From:
Indiana, USA
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Posted 8 Mar 2013 2:30 pm
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Wow! Thank you all for your input on this. Really helpful info! I think I'm going to stay with 6L6's for now. But, when it needs retubed, I may consider the further mods required for 6550's. We'll see.
Yeah, I agree the reverb circuit seems a bit cold to my ears too, but the price I got this thing for, I really couldn't complain about that too much. I am open to any suggestions on how to improve it. I guess, just use the schematic to rewire it closer to an older 85 watt Twin Reverb circuit and copy that (not sure if that'd work, but it's a thought).
I am just thrilled that the 6 string guitar community doesn't like these amps very much. It's all that much more interesting to me to take something that doesn't work as well for their tastes (I've read a lot of ugly comments on the web about the UL amps) and turn it into a cool sounding "clean machine" for a pedal steel application.  |
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Brett Lanier
From:
Madison, TN
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