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Post subject: Re: Fender 60's Blackface Bassman Restoration
Posted: Wed Dec 11, 2013 11:22 pm
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" One more thing, how do I tell if the amp is biased properly? "

It's hard to tell if the amp is biased properly, just by listening to it. Unless the amp is far off recommended bias point. Too cold = sterile tone, sometimes with oddball overtones. Too hot = early overdrive (in the volume range), "red plating" of overheated tubes, and/or amp running much too hot.

The amp tech that R&R's your amp should also adjust the bias, for whatever 6L6GC's you decide to use. This will not only give you primo tone, but longer tube life.


As for the buzzing in NORMAL channel--- the input tube (1st half of V3) of the NORMAL channel is unique to that channel. Could be bad contact (need contact cleaner) or bad tube. Tube is third from right, looking at the back of the amp. Either a 7025 or 12AX7.


http://www.webphix.com/schematic%20heav ... _schem.pdf



Good luck! A very sweet amp! All Blue Molded coupling caps. Don't let anyone replace them --- unless they are leaking DC.


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Post subject: Re: Fender 60's Blackface Bassman Restoration
Posted: Thu Dec 12, 2013 1:16 am
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Yeah, WF !!! If you know how to discharge the amp..... cleaning all of the pots, input jacks, and tube sockets may very well get the guy quieter. The channels are seperate, from each other, until they meet at the phase inverter tube(V4) and proceed through the power amp section. It could very well be that the normal channel input jacks(or pots) are dirty. The input jacks need to have the shorting connections working. You'll see these as an extra tongue, on each input jack. It's a simple, spring type of mechanism. But the connection must be good! And of course, Beemer nailed the bias scenario!!! In a way, you don't want to mess with the amp's synergy(stability). So maybe, just clean up what you have. JMO, Art

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Post subject: Re: Fender 60's Blackface Bassman Restoration
Posted: Thu Dec 12, 2013 2:47 pm
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aclempoppi wrote:
It could very well be that the normal channel input jacks(or pots) are dirty. The input jacks need to have the shorting connections working. You'll see these as an extra tongue, on each input jack. It's a simple, spring type of mechanism. But the connection must be good!


+1

An "open" input jack could very well be the reason for the spurious buzz emanating from an unused channel. Best to check each of them statically with a DVM to ensure the contacts of the jacks are closed when no plug is inserted.

Arjay

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Post subject: Re: Fender 60's Blackface Bassman Restoration
Posted: Thu Dec 12, 2013 4:42 pm
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Image

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Does this screw mean anything to anyone? I found it inside the cabinet.
Image

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Last edited by wferguson on Thu Dec 12, 2013 6:29 pm, edited 1 time in total.

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Post subject: Re: Fender 60's Blackface Bassman Restoration
Posted: Thu Dec 12, 2013 6:12 pm
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Definitely not bass guitar speakers. Not really guitar speakers either. And it looks as if the cab's baffle board has been replaced by one fabricated from half-inch plywood (likely to better support the weight of 30 lbs worth of alnico alloy contained within those D130's).

That wayward screw is entirely spurious -- it belongs nowhere on a vintage Fender amp.

Arjay

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Post subject: Re: Fender 60's Blackface Bassman Restoration
Posted: Thu Dec 12, 2013 6:31 pm
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A quick search pulled up that these speakers are from the 1950's. What would be the best replacement? Try to find the original factory speakers or buy a newer type? Thanks for all the help and info Arjay.

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Post subject: Re: Fender 60's Blackface Bassman Restoration
Posted: Thu Dec 12, 2013 6:48 pm
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Those are pretty darn good speakers. How do they sound? Maybe just re-cone them. I have a D130F ("F" is just for Fender, I believe) in my Pro and I would NOT sub any other speaker. It's a tone monster.

The D140 or D140F is the 15-inch bass instrument speaker by JBL. AFAIK.

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Post subject: Re: Fender 60's Blackface Bassman Restoration
Posted: Thu Dec 12, 2013 6:54 pm
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If I were to get a vintage correct baffle board made would it be able to hold the two speakers, or would it collapse like Arjay said?

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Post subject: Re: Fender 60's Blackface Bassman Restoration
Posted: Thu Dec 12, 2013 8:42 pm
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If you plan to keep those speakers in it, you're prolly better off with the plywood than MDF. Whomever originally performed the mod seems to have known what they were doing.

I've just realized that this is not a Bassman cab at all. What you have is a Showman 15 enclosure which has been converted from a single fifteen (with tone-ring baffle board) to a 2 x 15 configuration. The giveaway clues are the rear panel with the support slats glued to the inside and the mis-orientation of the grill-cloth weave.

Arjay

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Post subject: Re: Fender 60's Blackface Bassman Restoration
Posted: Fri Dec 13, 2013 4:31 pm
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Or could it be a dual showman cab?

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Post subject: Re: Fender 60's Blackface Bassman Restoration
Posted: Fri Dec 13, 2013 6:48 pm
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wferguson wrote:
Or could it be a dual showman cab?


No. Dual Showman enclosures did not have those support slats I mentioned on the rear panel. They were used solely on the tone-ring cabs......1 x 10 (first-year piggyback Tremolux), 1 x 12 (early Bassman piggyback, first-year piggyback Bandmaster, and Showman 12) and 1 x 15 (Showman 15).

Arjay

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Post subject: Re: Fender 60's Blackface Bassman Restoration
Posted: Tue Dec 17, 2013 11:12 am
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I was wondering how that bassman head fit so nicely on top of the upturned cabinet... A 2x12 is 21" tall vs a 24" tall showman cabinet. Makes sense now...

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Post subject: Re: Fender 60's Blackface Bassman Restoration
Posted: Tue Dec 17, 2013 12:21 pm
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Barely_Oakely wrote:
I was wondering how that bassman head fit so nicely on top of the upturned cabinet... A 2x12 is 21" tall vs a 24" tall showman cabinet. Makes sense now...


+1

At the outset I assumed the cab was one of those transitional big-box Bassmans (26"W x 39"H x 11½"D made only in 1966) but when I spotted the support slats on the inside of the rear panel and saw that the grill cloth weave was oriented to the horizontal instead of the vertical I finally put it all together. The clincher was the plywood baffle and the center partition that did not completely span the interior of the box. The non-original lumber seems to be pretty well aged so I'd assume that the conversion occurred quite some time ago.

Arjay

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