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Topic: NAD - 67 Dual Showman |
Tim Whitlock
From:
Colorado, USA
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Posted 9 Feb 2015 3:22 pm |
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Fate unexpectedly dropped this little gem in my lap. It is a 1967 Fender Dual Showman top. There are just a couple of small nicks in the tolex, otherwise it's in very good condition.
This one definitely has that vintage blackface magic. Although it is essentially the same AB763 circuit, somehow it sounds worlds apart from my Twin Reverb. The vibrato is especially nice and buttery smooth. I'll have to ask my tech if he can figure out why. Also the way the tone controls interface seems smoother and not so drastic as on the Twin. The Twin seems to have spots on the tone controls where it jumps from mud to shrill with very little middle ground. The sweet spot is much wider with the Showman.
My Mustang III has been a dependable lightweight workhorse, but I think it's going downstairs for a while, while I honeymoon with this beauty.
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Tom Wolverton
From:
Carpinteria, CA
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Posted 9 Feb 2015 3:52 pm
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Tim, what kind of speaker are you running with it?
_________________
To write with a broken pencil is pointless. |
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Tom Gorr
From:
Three Hills, Alberta
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Posted 9 Feb 2015 4:39 pm
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| Seems to me I saw some used reissues in a music store.. are the reissues any good? |
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Jack Hanson
From:
San Luis Valley, USA
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Posted 9 Feb 2015 5:05 pm
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Fantastic amp. If it's stock, the output transformer wants to see a 4-ohm load. Hook it up to a BW 1501-4 and you'll be in tonal nirvana.
Careful with a JBL. They're easily blown up by Showman and Dual Showman amps. (Please don't ask why I know.) |
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Tim Whitlock
From:
Colorado, USA
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Posted 9 Feb 2015 5:31 pm
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| Currently I'm running it through a 2x12 cabinet I built. It's loaded with two Standel ceramic 12" speakers and sounds pretty great. I plan to build a compact 1x15 cab and use a Jensen or Eminence neodymium speaker. |
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Gary Cosden
From:
Florida, USA
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Posted 10 Feb 2015 9:10 am
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| I have the same amp. Ken Fox worked it over for me about 5 years ago. I tried it with 1 BW1501-4 as well as 2 12" Weber Michigans and 2 12" Eminence CRs (my favorite) and it sounds killer. After 5 years I could use some new power tubes but I have to say this amp is hard to beat. |
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Cartwright Thompson
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Posted 10 Feb 2015 12:29 pm
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| I had one of those and I wish I never sold it. I ran it with two GE 6550's (beef up the screen resistors and re bias) into an 8 ohm D-130. Probably put out about 70 watts. Plenty of power and superb sound, especially with a blackface reverb unit. |
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Bob Hoffnar
From:
Austin, Tx
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Posted 10 Feb 2015 1:58 pm
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| Tom Gorr wrote: |
| Seems to me I saw some used reissues in a music store.. are the reissues any good? |
The reissues are not related in any way (other than cosmetic) to the older Fender amps. In my experience new Fenders are crap.
Tim,
Those blackface Showmans are great amps. My 66 sounded better than any twin also and I don't know why either.
It was my favorite amp until I bought a Milkman 85 head.
I use a THD 2x12" cab with old orange back JBL D120's. I often play pretty freakin loud, sometimes with extreme distortion
(Durham Crazy Horse), and I have not blown a speaker yet.
Those showmans are golden for recording. You can run speaker cable to the iso booth and keep your tone. Also they are easier to hump to gigs than a twin with the weight split.
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Bob |
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Tom Wolverton
From:
Carpinteria, CA
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Posted 11 Feb 2015 8:11 am
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One other nice thing about a Showman head is when you play a gig on a flimsy stage, like at a festival or street fair. There is no spring reverb to crash on you when the stage vibrates too much. And reverb pedals have gotten so darn good. I still love a built in spring reverb best, but there certainly are times when it is a liability.
I run my head thru a K-130 or Telonics neo 15. I blew up a D-130F. I won't be running those anymore. : )
_________________
To write with a broken pencil is pointless. |
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Stephen Cowell
From:
Round Rock, Texas, USA
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Posted 11 Feb 2015 10:31 pm
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In the Fender amp reverb circuit there's a 'pinch point' for the signal... it all has to go through a big resistor, bypassed by a tiny capacitor... this is what you get away from when you use a non-reverb Fender. Small changes to the resistor and capacitor have large effects on the signal's frequency response, and it's a well-known fact that the more (and bigger) resistors your signal goes through, the more it degrades.
Here's the schematic:
http://schematicheaven.net/fenderamps/twin_reverb_ab763_schem.pdf
Note the 3.3meg/10pF network... that's the tone suck part of it. It's necessary to prevent reverb feedbacking into itself... saved Fender a buffer stage.
_________________
Too much junk to list... always getting more. |
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Tim Whitlock
From:
Colorado, USA
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Posted 12 Feb 2015 2:35 pm
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So the missing reverb circuit could be the tonal difference I am hearing?
I wasn't really looking for another amp but the Showman was offered as trade for a piece of gear I no longer needed and it was too good to pass up. This creates a dilemma. I would sell my Twin Reverb but it was custom built for me by a friend. The Showman sounds incredibly good but I don't need two 85 watt tube amps. Decisions... |
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Tom Wolverton
From:
Carpinteria, CA
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Posted 12 Feb 2015 3:19 pm
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| Tim Whitlock wrote: |
| ... but I don't need two 85 watt tube amps. Decisions... |
Life is short. Keep 'em both and enjoy them.
_________________
To write with a broken pencil is pointless. |
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Chris Bauer
From:
Nashville, TN USA
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Posted 19 Jun 2015 3:56 pm
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| Any reason a Dual Showman could/would/should care if you use one speaker out or both? Plus - even more of a novice question here - I assume that it wants to see no more than an 8 ohm load total and not per speaker jack, yes? (So, two 8 ohms speakers in parallel in one jack should be okay but if using both outputs, should each speaker be 4 ohm or could they both be 8 ohm?) |
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Jerry Hedge
From:
Norwood Ohio U.S.A.
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Posted 19 Jun 2015 6:27 pm
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| For optimum performance from a Dual Showman, both speakers should be 8 ohm. The output transformer is wound for 4 ohms, there isn't an 8 ohm tap. |
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Chris Bauer
From:
Nashville, TN USA
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Posted 19 Jun 2015 6:56 pm
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But would you use an 8 ohm in each output? I guess a part of my under-informed question is if the outputs are fully independent. (I assume not since there's only one OPT.)
For the electronically challenged among us, could one of you post one and two output multiple speaker configurations that would work appropriately for amps wanting to see either four or eight ohms? (I know, I know. I should know this stuff by now but I don't...)
Last edited by Chris Bauer on 19 Jun 2015 7:33 pm; edited 1 time in total |
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Stephen Cowell
From:
Round Rock, Texas, USA
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Posted 19 Jun 2015 7:32 pm
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Fender amps have paralleled output jacks... so normally, it would not matter which output you used, or both at the same time... *but*...
The normal output has a shorting contact! If you only plug into 'ext' you won't get much... and you can fry your OT in the process. They do this because the amp will last longer into a short than into an open... didn't help me with my learning experience, though... I burned one up learning this in my youth.
So use the Normal one first, then Ext.
_________________
Too much junk to list... always getting more. |
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Chris Bauer
From:
Nashville, TN USA
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Posted 19 Jun 2015 7:38 pm
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| Thanks, Stephen. And I assume that when an amp is looking for a 4 ohm load, you need to max out at 4 ohms per output and, likewise, when it's looking for an 8 ohm load, you need to top out at 8 ohms per output, yes? (But that, at least ideally, when looking for 4 or 8 ohms, the combination really should be 4 or 8 ohms respectively. Have I finally got that right?) |
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Godfrey Arthur
From:
3rd Rock
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Posted 19 Jun 2015 8:58 pm
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You'll get a fuller tone out of 4 ohms but you could use an 8 ohm, it will just be less loud.
If a JBL, the E series will handle load better than the older D series, but the E-130 15 incher is an 8 ohm speaker, rated for 300 watts max, 150 watts nominal. The SPL on the E-130 is 105db so the speaker will sound loud by that rating.
Depending on your proposed use, less volume may not be a problem if you want a certain speaker's tone.
JBL E-130 8 ohms.
BUT, if you're wanting dual speakers, then two 8 ohm speakers wired in parallel will bring the impedance to 4 ohms on the money!
_________________
ShoBud The Pro 1
YES it's my REAL NAME!
Ezekiel 33:7 |
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Cartwright Thompson
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Posted 20 Jun 2015 1:36 am
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| When you remove two power tubes, either the outside or inside pair, you cut the power output in half. Still plenty of power ( especially through an efficient speaker like a d-130) and the OT will want to "see" 8ohms instead of 4. |
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Stephen Cowell
From:
Round Rock, Texas, USA
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Posted 20 Jun 2015 8:18 am
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| Chris Bauer wrote: |
| Thanks, Stephen. And I assume that when an amp is looking for a 4 ohm load, you need to max out at 4 ohms per output and, likewise, when it's looking for an 8 ohm load, you need to top out at 8 ohms per output, yes? (But that, at least ideally, when looking for 4 or 8 ohms, the combination really should be 4 or 8 ohms respectively. Have I finally got that right?) |
Sorry... I wasn't clear. There are not separate outputs... the jacks are connected together. When it says 4ohms, that's the total connected. Since they're in parallel, you have to divide by two when you connect two equal impedances... so two 8ohm loads, one to each jack, gives the amp 4ohms. Two 4ohm loads give the amp 2ohms, which it will tolerate unless you drive it too hard... same for two 16ohms, which gives you 8ohms. Running at 2 heats up the transformer... running at 8 brings the possibility of arc'ing a socket or transformer... running it at 16ohms will kill it quickly.
So when you use one jack, use the Normal one...then use the Ext one for more speaker. Try to keep the combined load at 4ohms for longest service of your tubes and amp. Tube amps need to be adjusted when the big (output) tubes are replaced... find a good tube amp tech in your area. Buy your output tubes from him if you want warranty on them.
_________________
Too much junk to list... always getting more. |
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Chris Bauer
From:
Nashville, TN USA
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Posted 20 Jun 2015 9:21 am
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| Thanks, Stephen. Exactly what I was looking for. It's what I thought to be true but, given my long and storied history of total electronic ineptitude, I wanted to actually be sure. |
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Tony Prior
From:
Charlotte NC
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Posted 21 Jun 2015 1:49 am
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I also have a 67 Showman head, with a 4 ohm date correct OT which makes it a Dual Showman I suppose. It's the only vintage Fender amp I have left and I can't part with it. The normal channel, although it just has Volume , Treble and Bass, (no mid control) , is the best Fender Normal channel tone I have ever owned ! And I can't say why !
This one was a mess when I acquired it and required new tolex. It's like brand new now, but was restored and with new E-Caps.
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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 |
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