Tubes for Twin

David Cook · Post by **David Cook** » 30 May 2016 1:32 pm

I saw the sacred steel Lee brothers at the Florida Folk Festival this weekend and the pedal steel player( I think his name was Chris) was talking to me about his tube amps. I have a blackface 85 watt Twin that doesn't quite cut it with a loud rock band. He suggested putting a 12AU7 int the 1st preamp hole for clean tone. He also suggested changing something with the power tubes but I can't remember what he said. I am looking for a cleaner tone with less breakup. He said that I might have to turn the volume up.

thanks

Cartwright Thompson · Post by **Cartwright Thompson** » 30 May 2016 1:47 pm

I think a 12AU7 is a little extreme, try a 12AY7.
If a twin reverb doesn't cut it, there is something wrong with the equation.

Walter Killam · Post by **Walter Killam** » 30 May 2016 5:39 pm

Get a matched quartet of hard/blue 6L6 tubes for more clean volume. That said if you can't keep up with ANY Twin, you may be in the wrong band

John Billings · Post by **John Billings** » 30 May 2016 7:51 pm

Get Mullard EL37s for the power tubes,

Paul Sutherland · Post by **Paul Sutherland** » 30 May 2016 8:02 pm

You might want to look up the gain structure of various preamp tubes. I'm no expert, but it's my understanding that a 12AU7 has significantly less gain than a 12AX7, so it drives the power tubes significantly less, which means a cleaner tone, but less volume. A properly adjusted twin using 12AX7 preamp tubes is plenty clean. My Twin sounds it's best when it's running on 8 or above on the volume, but I usually can't set it that high. It sounds fabulous in the 8 plus range.

A don't know anything about changing power tubes to increase the volume from a twin. But the efficiency of the speakers can make a difference. A highly efficient set of JBLs or Altecs can make the amp sound significantly louder than one using the stock Jensens, etc.

Dave Meis · Post by **Dave Meis** » 30 May 2016 9:30 pm

Never tried the EL 37's, but running 7581 A's (the 'A' is important!) in my UL twin, and liking them. They're a 35 watt tube. I'd go with a 5751 in the pre-amp .. I've had noise problems with AT's and AY's in V1, but you may not.

Taming the knobs with a lower gain value tube makes it little easier to find the sweet spot, and having a master volume keeps it there! Somehow I can't imagine a twin not being enough..

John Billings · Post by **John Billings** » 30 May 2016 10:43 pm

I have a bunch of 7591A tubes. Are they a plug in replacement? Doesn't really matter as I have a new Dr. Z Surgical Steel that blows the Twin outa the water. Split Twin with Rick Johnson cabs for sale soon. It's a great amp, but cant compete with the Dr. Z.

Dave Meis · Post by **Dave Meis** » 30 May 2016 11:12 pm

John.. don't know much about the 7591A's.. I think they were used in Ampegs and Macs. I went with the 7581A's for the high plate voltage in the UL twins, and the fact the they were direct replacements for the 6L6 GC's..just bias and go.

John Billings · Post by **John Billings** » 30 May 2016 11:32 pm

Dave,
The best tube replacements for 6L6s that I've ever found are Mullard EL37s. But break out your wallet!

David Cook · Post by **David Cook** » 31 May 2016 8:25 am

Maybe it's the speaker(Telonics neo 15inch) the blackface Twin gets plenty loud enough but it doesn't stay clean. Someone once said that plugging into the attenuated 2nd channel is the same as changing to an AY or AU. Should I unplug the V1 because I don't need the normal channel? Would this help the cleanest

Dave Meis · Post by **Dave Meis** » 31 May 2016 9:26 am

If it were me (and it's not, but I've been there), I'd put in a new set of high power tubes in the power section, bias them 'cool', and go from there. Bias is important to keeping it clean, and tubes wear out. Most amps are set up for 'guitar' players,and they don't want that 'clean', but for steel, it's important. Send the chassis to a tech if you're not familiar with doing the work, and tell them what you want..clean, clean, clean! They can help you if they know what you want. Hope this helps.
edit to add: removing the tube in V1 would probably 'warm up' the amp, and may not be what you want.. try it and see.. it's free!

Mike Neer · Post by **Mike Neer** » 31 May 2016 9:31 am

Man, I just bought a100 watt Twin Reverb with K120s over the weekend for $500. What an amp for steel, and what load to bear! Fortunately, it's staying put in my studio.

Dave Meis · Post by **Dave Meis** » 31 May 2016 10:13 am

John Billings wrote:Dave,
The best tube replacements for 6L6s that I've ever found are Mullard EL37s. But break out your wallet!

Wowzeer!! Checked out some of those on line.. I'd have to get a second mortgage or sell my guitar.

John Billings · Post by **John Billings** » 31 May 2016 10:50 am

Dave,
Years ago I bought a 1952 Fender Pro Amp for $125. It came with 2 EL37s! What a cool amp!

Dave Meis · Post by **Dave Meis** » 31 May 2016 11:32 am

For a $125, it MUST have been a few year ago!

I've scored some good pre-amp and power tubes over the years in old amps..old GE and RCA 6L6's, and a guy gave me a bag of RCA clear top 12AU7's in original boxes out of an organ he was 're-cycling' for someone, but I haven't found much use for those. Never anything like Mullards or Telefunkens..but..I'll give you $130 and pay half the shipping on that '52!

John Billings · Post by **John Billings** » 31 May 2016 1:22 pm

Organs are good sources for tubes. Hammond used primo tubes! Amperex EL84s, etc. Keep an eye out for Fifties Hi Fi units. Good tubes abd a lot had Jensen speakers.

Donny Hinson · Post by **Donny Hinson** » 1 Jun 2016 6:30 am

The problem with the B/F design is, by the time you dial in some tones for a pedal steel, almost half of the output is gone. A lower gain preamp tube will reduce the distortion, but it also reduces the total power available. The result is a cleaner tone that isn't as loud. Sonetimes that works, and sometimes it doesn't.

Patrick Rusert · Post by **Patrick Rusert** » 1 Jun 2016 7:32 am

David Cook wrote:Maybe it's the speaker(Telonics neo 15inch) the blackface Twin gets plenty loud enough but it doesn't stay clean. Someone once said that plugging into the attenuated 2nd channel is the same as changing to an AY or AU. Should I unplug the V1 because I don't need the normal channel? Would this help the cleanest

What's your normal master volume setting? I've noticed that if you have a hot pickup and/or an active volume pedal, it can be very easy to overdrive the first gain stage on almost any amps, but Fenders in particular. Especially if you've gotten into the habit of playing on the upper range of the volume pedal's throw.

This might have been what the sacred steeler was getting at when he said to turn the master volume up.

John Billings · Post by **John Billings** » 1 Jun 2016 10:37 am

Donny,
That's something that Dr. Z has dealt with in his new Surgical Steel amp.Instead of using a 12AX7 or similar tube, He;s using an EF86 in the preamp to drive the KT88s. It really handles the higher output of steel pickups and effects much better. I'm really loving the amp.

Donny Hinson · Post by **Donny Hinson** » 1 Jun 2016 4:31 pm

Patrick Rusert wrote: What's your normal master volume setting? I've noticed that if you have a hot pickup and/or an active volume pedal, it can be very easy to overdrive the first gain stage on almost any amps, but Fenders in particular. Especially if you've gotten into the habit of playing on the upper range of the volume pedal's throw.

This might have been what the sacred steeler was getting at when he said to turn the master volume up.

Very true, Patrick! The master should always be "dimed" if you want the cleanest signal. In addition to different tubes, you can also (as a designer or repairman) lower the plate voltage, or change the tubes bias to reduce the gain of a stage.

David Cook · Post by **David Cook** » 1 Jun 2016 5:24 pm

I am using a 60"s blackface Twin with no master volume. I am using a Shobud Professional with a Hilton pedal. I usually run the Twin on 3 or so so I think i could stand a loss in some voltme

Matthew Dawson · Post by **Matthew Dawson** » 1 Jun 2016 6:14 pm

What speaker is in the Twin? You could spend upwards of $300 on NOS 6L6GCs which may or may not (likely not) be well matched or get high efficiency speakers like JBLs or the new Telonics. DO NOT attempt to substitute a 7591 for a 6L6. This will break the tube and/or the amp. The 7581 in a pin-compatible 6L6 replacement. The 7591 is not.

Dave Meis · Post by **Dave Meis** » 4 Jun 2016 10:34 am

John Billings.. sent you an e-mail.

John Billings · Post by **John Billings** » 4 Jun 2016 11:27 am

Dave,
I didn't get it. Try a Forum PM.
JB

Dave Meis · Post by **Dave Meis** » 4 Jun 2016 2:49 pm

John...PM sent. Thanks! Dave

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