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 Post subject: Bassman question for Arjay
PostPosted: Fri May 06, 2011 8:35 am 
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Okay, finally started working on this beast. Pretty clean. Below are some photos. I do have the back panel but removed it for the photos. Chrome hardware is pretty clean.

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Already has a grounded cable although the ground prong is broken off the plug, I can replace that easy enough. It looks as though the "ground/polarity" switch has been jumperred and I believe the death cap is already gone. But maybe not...
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If all of this looks correct, then all I should need to do is install an new 15amp plug on the power cord and let 'er rip. If you want to look at the full size photos, try here: http://www.flickr.com/photos/ar_photog/

I still need to open the speaker cab and check the old speakers. Thankfully, the back comes off. :)

Art


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 Post subject: Re: Bassman question for Arjay
PostPosted: Fri May 06, 2011 9:42 am 
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Looks like it's all there -- except for that wonky set-up for the bias cap. I'd ditch that pair of IC's in favor of a single 100/100 (either Sprague or F&T). Have you inspected the filters under the doghouse?

Arjay

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 Post subject: Re: Bassman question for Arjay
PostPosted: Fri May 06, 2011 9:53 am 
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Here's the way I wire a new cord with a 3 prong plug....the hot going through the fuse.
http://www.theguitarfiles.com/guitarfile644.html


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 Post subject: Re: Bassman question for Arjay
PostPosted: Fri May 06, 2011 10:28 am 
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Rebelsoul wrote:
Here's the way I wire a new cord with a 3 prong plug....the hot going through the fuse.
http://www.theguitarfiles.com/guitarfile644.html

Yeah, I noticed the fuse was not on the hot side. Guess the original owner didn't want to make too many changes.

Art


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 Post subject: Re: Bassman question for Arjay
PostPosted: Fri May 06, 2011 10:35 am 
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Retroverbial wrote:
Looks like it's all there -- except for that wonky set-up for the bias cap. I'd ditch that pair of IC's in favor of a single 100/100 (either Sprague or F&T). Have you inspected the filters under the doghouse?

Arjay


Waiting until I get back to FL to pull the doghouse. Probably install a new AC plug this weekend. And pull the back off of the speaker cab and get some model numbers off of the spkr frames. That's a 71 model and I forgot to take a photo of the info plate on that. But it is a Model "VT Bassman 15" vertical with thumbscrews to mount the head.

Thanks,
Art


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 Post subject: Re: Bassman question for Arjay
PostPosted: Fri May 06, 2011 11:33 am 
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Art1 wrote:
Rebelsoul wrote:
Here's the way I wire a new cord with a 3 prong plug....the hot going through the fuse.
http://www.theguitarfiles.com/guitarfile644.html

Yeah, I noticed the fuse was not on the hot side. Guess the original owner didn't want to make too many changes.

Art

I know that most vintage Fenders are not rewired to that diagram,at least the ones I have,I have had to change..... and people I know that don't make those changes,and usually it's not an issue,but knowing how unsure you can be of the safety of where you're plugging into,having two legs that can carry current attached to the fuse and fuse holder is risky.
The link explains that well,and I'm sure other people will disagree.


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 Post subject: Re: Bassman question for Arjay
PostPosted: Fri May 06, 2011 12:32 pm 
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At any rate, there are some cracks in the baffle near the mounting screws of the bottom speaker. (that explains the vibration noise.) So this will be the perfect time to replace that particle board with the real deal. (plywood.) The original speakers are functional but could sound better. 40 years old, what can one expect? Looks like CBS was not using batting inside these enclosures. So, for for a minimal amount of $ everything will be up to snuff. For a couple of bills more, I can replace the speakers.

Something like 37 screws, time I invested in a cordless screwdriver. :lol:


Art


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 Post subject: Re: Bassman question for Arjay
PostPosted: Fri May 06, 2011 2:50 pm 
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Leo NEVER used plywood for baffle boards in any of the piggy-back amps with sealed enclosures, even when ply was still used in the early '60s brownface combos, and with good reason.

He discovered when using plywood at both the front and rear of his prototype bass-reflex cabs that this material caused unexpected (and quite audible) vibrational noises whenever the speakers were pushed hard.

Thus Fender's switch to MDF, which was later extended to include the entire line of amps merely to simplify the factory's ordering and inventory process of materials.

Arjay

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 Post subject: Re: Bassman question for Arjay
PostPosted: Fri May 06, 2011 3:18 pm 
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Retroverbial wrote:
Leo NEVER used plywood for baffle boards in any of the piggy-back amps with sealed enclosures, even when ply was still used in the early '60s brownface combos, and with good reason.

He discovered when using plywood at both the front and rear of his prototype bass-reflex cabs that this material caused unexpected (and quite audible) vibrational noises whenever the speakers were pushed hard.

Thus Fender's switch to MDF, which was later extended to include the entire line of amps merely to simplify the factory's ordering and inventory process of materials.

Arjay



Then I should probably use 1/2 MTF (I think that is the particle board) ??? But not sheathing material? I know you have rebuilt many of these cabinets and value your opinion.

Thanks,
Art


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 Post subject: Re: Bassman question for Arjay
PostPosted: Sat May 07, 2011 2:03 am 
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It would make sense that MDF would not transfer as much vibration,seems to be a pretty dead piece of material...never thought of it since I only have combo amps...learn something new everyday.


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 Post subject: Re: Bassman question for Arjay
PostPosted: Sat May 07, 2011 2:26 am 
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Sonically, MDF is relatively inert. But it does in fact transfer sub-sonic energy to a cabinet case quite well, which accounts for the legendary resonance of all pine-board Fender enclosures (whether combo or bass-reflex).

When I restored a '65 Fender Showman cab two summers ago I was fully prepared to replace anything that seemed wonky, including the baffle board since the enclosure had suffered some minor water damage to the bottom. But the OEM baffle board was still in excellent shape, requiring only a new felt anti-chafing strip in the center (this material insulates the cloth from the center grill frame plank to prevent abrasion of the cloth and to minimize cloth "sag" in the middle of the baffle). And this MDF was nearly forty-five years old, with some thirty pounds worth of magnetic alnico alloy mounted to it for the lion's share of its life.

Leo knew what he was doing.

HTH

Arjay

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"Here's why reliability is job one: A great sounding amp that breaks down goes from being a favorite piece of gear to a useless piece of crap in less time than it takes to read this sentence." -- BRUCE ZINKY


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 Post subject: Re: Bassman question for Arjay
PostPosted: Sat May 07, 2011 8:42 am 
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I couldn't resist. I plugged the little Champion 600 into the 2x15 cab. Awesome tone out of that little amp with 40 year old speakers. Very nice overdrive. Surprising how loud a 5 watt amp can be. 8) I think I am going to keep the stock speakers until they finally die.


Art


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 Post subject: Re: Bassman question for Arjay
PostPosted: Sat May 07, 2011 9:31 am 
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I often connect my '68 Bronco to the Dual Showman cabinet for that very vibe. It's awesome!

Have you cracked the Bassman enclosure open to ascertain the speaker type yet?

Arjay

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"Here's why reliability is job one: A great sounding amp that breaks down goes from being a favorite piece of gear to a useless piece of crap in less time than it takes to read this sentence." -- BRUCE ZINKY


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 Post subject: Re: Bassman question for Arjay
PostPosted: Sat May 07, 2011 10:37 am 
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They are Fender branded but I didn't write down the chassis numbers :( I ain't taking all those screws off again this weekend. :lol:

Art


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 Post subject: Re: Bassman question for Arjay
PostPosted: Sat May 07, 2011 11:14 am 
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Art, meet my bested friend. I get the long extension screwdriver head and good set of drill bits (I use Bosch). Life becomes so much easier. Like the skies open up. :)


http://www.amazon.com/dp/B000MPP558/ref ... B000MPP558


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