Blackfaced Twin running 4x6V6's good for steel?

Benjamin Wolfram · From: Victoria, Australia

Found a potential amp, a blackfaced Twin running on four 6V6s with a couple of Jensen C12 type speakers in it...going to check it out but just wanted to see if there would be any reason why 6V6s might not be as good for pedal steel. Still big headroom etc. etc. so I'm assuming it would still be great Smile

Tim Marcus · From: San Francisco, CA

Wonder how they worked around the output impedance mismatch on that one. Are they 8 ohm speakers? What's the total load?

6V6 tubes sound great - they generally have lower power than the 6L6. They have a different impedance though, so the output of the amp will not be 4 ohms any longer.

The breakup on 6V6's is a lot sweeter than the 6L's. You probably won't want to break the amp up with steel, but if you do it might be nice.
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Benjamin Wolfram · From: Victoria, Australia

Well then since I am predominantly a regular six string guitarist that would probably work very well for me.

I think it's got a Vintage 30 clone and a C12 clone in it which are really more "guitar" speakers but it's probably an 8ohm output if it's been modded like that, no idea though.

Description says it kind of sounds like a souped up Deluxe.

Might try and swap out the speakers for a single 15" if I get it.

Tony Prior · From: Charlotte NC

Theoretically speaking, the impedance mismatch may not be as big a deal as the plate voltage. The Twin is most likely pushing above +450 for the 6L6 DC, 6L6's are made for this. 6V6's however are generally known to be able to handle less plate voltage, more so around +400, but the Deluxe Reverbs run in the +430 range pushing the heck out of the poor 6V6's. So much for that RCA tube reference guide! . Now you have pushed them even farther. My take is the 6V6 will degrade in performance and talk about running hot !

For Steel Guitar clean, go back to the 6L6 x4...but I think you already know that.

Back in the olden days with the Bassman and BMaster heads, we didn't give it much thought, we stuck in 6V6's when we needed a tube because that's what we had ! Rock and Roll didn't suffer...the show went on...
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David Mason · From: Cambridge, MD, USA

It seems like since the internet got up enough steam to de-volve into jillions of specific websites, there's been a lot more to worry about when attempting to play some music. I don't think we blow up any less stuff than before, but we're a lot better educated about it when we do.

Tim Marcus · From: San Francisco, CA

I've been able to push the new production 6V6's really really hard without a problem - I don't think you need to worry about blowing anything up even with the high plate voltage

however, the impedance thing matters on a tone level. If you want nice low end articulation, its nice when the numbers add up

but yeah - you'll be fine don't worry about it!
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Dave Mudgett · From: Central Pennsylvania and Gallatin, Tennessee

Is this a 60s blackface Twin or a later SF with a blackface plate or a reissue? I think 450VDC or so is probably about normal for a 60s blackface Twin - that's pushing it for a set of 6V6's. But some later Twin Reverbs are pushing near 500VDC on the B+: 470-490 is not unusual at all on some I've had. I would not put any 6V6 in that situation, not even a NOS one, much less the newer production. It's one thing being OK while trying it out in a store or as a short-term emergency sub (if you make sure the bias is in the right range). But I think night after night, year after year of hard use (pedal steel or hard rockin' guitar is hard use, IMO) are likely to take their toll.

Deluxe Reverbs definitely push 6V6's pretty hard - 420-430 VDC with a design center of 350VDC. I've had newer production 6V6's poof on me, in fact one incident took out an output transformer - it took me a long time to find a period-correct replacement. But a good NOS 6V6 should be able to handle 420-430 if you don't bias it real hot. So I would check out anything over 430 very carefully. Bias is important if you're pushing the tube, I strongly suggest you check that out carefully.

The amp you're looking at may have a lower B+. One can change the power transformer or filtering circuit to give a lower plate voltage. I would check out that and the bias before I did anything else with that amp. If the power transformer is changed to be suitable for 6V6, you probably wouldn't want to go to 6L6. But if it's still honkin' a high plate voltage, you might want to think twice about what to do.

Impedance matching is important, but a bit off isn't a big deal on a stout Fender output transformer in good shape. It does affect the tone, no doubt, but as long as it's not hitting the OT with an abnormally heavy flyback voltage, that's a matter of taste which you should be able to discern by listening. Like Tim, I prefer mine matched as closely as possible, but I know guys who prefer 2-10" 8Ohm speakers in a Deluxe and it works OK for them.

My $0.02, YMMV.

Benjamin Wolfram · From: Victoria, Australia

The description says this:

originally a Silverface master volume amp that has been converted to Blackface specs, rewired with sprague orange drops by amp guru Allan Kelly. Complete with Blackface faceplate installed, running on 4 6V6's sounds more like a souped up Deluxe Reverb putting about 80watts

Whatever has been done has been done by a proper amp tech/guru type so I'd have to assume it's been done with everything in mind but I'll be curious to check it all out anyway, I'm sure I can give the amp guy who did it a call.

Tony Prior · From: Charlotte NC

Orange drops ? Well right there is a indicator. Typically amp guru's are chasing down the original BLUE Molded caps ( Mallory I believe ) which were used back in the day. Not sure how you claim to BF a master volume amp while it is still active.. Regardless it's most likely still a great amp...Maybe the face plate is what they are referring to.

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Benjamin Wolfram · From: Victoria, Australia

Really? So what it's not even a proper Blackface job is it? I thought the orange drops were a good cap or are they typically used in Marshalls or something else?

Tony Prior · From: Charlotte NC

OD's are good caps, but they do not have the same preamp tone as the original Blue Mallory caps in the tone stack.

Rebuilding an amp is one thing,calling it Blackfaced is quite another.

Marshal amps have a totally different tone stack than Fenders. Not to be compared.

" My 66 Corvette had a 327, I rebuilt it with a 350.. it's exactly the same "

Buying Fender amps, especially Vintage amps is an education, the unaware buyer can get hurt in a hurry. There are plenty of stock SF Twins out there, I would suggest getting one in the 68 thru 71 range, forget about the Blackfacing thing. Or just get that 65 RI Twin, it's a fine amp.

t
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Benjamin Wolfram · From: Victoria, Australia

Apparently this Twin is in great shape but the 6V6's mean that it's putting out 40-50 watts as opposed to the usual 80. Does anyone think this would be a problem and it wouldn't have the clean headroom I need for steel because it's less watts or because it's a Twin (as opposed to a 40 watt Bassman) it still won't break up very easily?

This info came from the amp tech himself who worked on the amp.

Dave Mudgett · From: Central Pennsylvania and Gallatin, Tennessee

Benjamin, that makes more sense. I was trying to figure out how you'd get more than 40-50 watts out of 4-6V6 tubes.

On the volume - it depends on how loud and clean you need to be. I can generally get by with a 50-watt Fender tube amp, but then again most people I play with these days don't have a scorching stage volume.

On the tone - if it sounds good, it is good. Only you can judge that for yourself. If it were me, I'd want to know, exactly

1. What version of the Twin Reverb it was originally.
2. What was done to it, in full detail, including any transformer and circuit changes.

My main concern would be whether or not the tubes are being pushed way outside their limits and if the amp is stable. Otherwise, again - if it sounds good, it is good.

Randy Gilliam · From: San Antonio, Texas, USA

Tony i Have a Mint 68 Twin Serial number 11866. AB 763, How Many Watts are These?. I Had 2 Jensen 12in Speakers Special Sesign Out Of a Reissue 65 Twin Installed, and all the caps and resistors Checked and replaced the Weak Ones. I Have only Played it at Home So Far. When My Back heals up I Will Try It. I Bought it a Month ago.Are The Original Speakers Worth anything, I Have one Only.Thanks Randy Gilliam. Question

Tony Prior · From: Charlotte NC

Randy, interesting question with regard to TWIN output power. The AB763 is known to have the "better" tone stack, as this circuit dates back to July 1963. I believe the next circuit was AC568 making that May 1968. Ok power, here's the deal. All of the TWINS, Showmans, Dual Showmans etc were based on the 85 watt circuit, no master volume. all the way up to and including 1971. 1972 introduced the master volume and bragged on 100 watts. The thing here is that somewhere along the line 69 or so, Fender also claimed 100 watts for these same circuits, with..uhh..no changes ! 85 watts became 100 watts with no power circuit changes. If you look this up in WikiPedia this is stated as well.

Now here is my theory...way back 1963 when Fender was rating amps who the heck knows what AC power they had in the building, maybe they based the math on 110 volts AC and achieved 85 watts. Fast forward to the end of the decade, Marshall, Vox, Mesa etc were bragging on 100 watts, Fender was still stuck at 85..but wait...enter the new math. I suspect they used a new equation to calculate output wattage going with the rating of the power transformer which was probably 125 VAC or more. So using 125 VAC as the AC reference gives them a higher output rating, so now we have 100 watts. Always keep in mind that we went from 85 to 100 watts ( 15%) with NO circuit change ! Good trick. The only legitimate way to increase the rated power was with a new equation, now known as "the new math". So is my 71 Twin 85 watts or 100 watts ? The answer is "YES".

That's my theory and I'm sticking to it. Smile

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Emmons L-II , Fender Telecasters, B-Benders , Eastman Mandolin ,
Pro Tools 12 on WIN 7 !
jobless- but not homeless- now retired 9 years

CURRENT MUSIC TRACKS AT > https://tprior2241.wixsite.com/website

Randy Gilliam · From: San Antonio, Texas, USA

This ons has the aluminum picture frame around the Grill Cloth, Does Not Have a Master Volume, I cant wait to try it on a Gig. Thanks Tony, Randy G. Very Happy

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