A piece of history--1963 Bassman

[rfgordon]

I got this late 1963 blonde Fender Bassman head in for a recap from a local studio. It is alleged to have been owned by James Brown at one time.

It was bone stock--NEVER been serviced! All I did was replace the electrolytics, and it rocks!

[jelle]

Cool amp. Even without the JB connection.

Death cap?

[rfgordon]

The client wanted it returned as original as possible, so he wanted the death cap and original cord left on.

[Bob-I]

The client wanted it returned as original as possible, so he wanted the death cap and original cord left on.

Dude's brave.

[benoit]

Dude's crazy.

True.

[morcey2]

Dude's crazy.

True.

No kidding.

Every amp I get in with a 2-prong cord and/or death cap gets a 3-prong and the death-cap removed if the owner wants me to work on it. It's easy enough to hang on to all the parts and put them back if a collector wants to buy it, but it isn't worth the liability involved for me to even touch it without that. I even throw that in for free.

If they don't want it, I won't work on it.

Matt

[Bob-I]

If they don't want it, I won't work on it.

Matt

Good policy Matt. The last person to service that amp before the electrocution will be the one named in the lawsuit.

[rfgordon]

I came up with a safety solution in this case, since I really didn't want to return a potentially unsafe amp.

This chassis uses a SS rectifier, so the rectifier tube socket hole has a cover on it. I soldered an eye to the end of a length of wire, attached it to the chassis with one of the screws holding that cover. I then zip-tied the wire down the length of the power cord and installed a new, three-prong plug on the end.

So now the amp is grounded AND still has the stock cord. It looks a bit aggie-engineered, but it's an instantly removable mod, should he want to sell the amp.

[Tonegeek]

I got this late 1963 blonde Fender Bassman head in for a recap from a local studio. It is alleged to have been owned by James Brown at one time.

It was bone stock--NEVER been serviced! All I did was replace the electrolytics, and it rocks!

I have one exactly like that one but in black tolex - its a '64. I think it is the 6G6b circuit. The clean sound (Normal channel) on that amp is my favorite of all the amps I have ever owned. It rocks when cranked too. To me, the presence control is what makes that amp so special.

[greiswig]

To me, the presence control is what makes that amp so special.

What's special about it? I looked on schematicheaven, and I can't make out the component values.

[Tonegeek]

To me, the presence control is what makes that amp so special.

What's special about it? I looked on schematicheaven, and I can't make out the component values.

I was referring more to the specialness of the sound and useability of the control (as in my mind opposed to the more prevalent DEEP switch) rather than the actual values.

The actual values in the feedback circuit, and presence control are:
56k feedback resistor from the speaker terminal
4k7 PI tail resistor
25k pot (wired as a variable resistor) in series with .1 cap across the tail resistor

Marshall uses this same arrangement a good bit so in that sense it is not so special. Sure sounds good though...

[MBD115]

I'll tell you what, thats about the cleanest layout I've seen in a Fender amp. Most Fenders I've looked in are a mess in there. That one looks pretty good!!!

Thanks for the pics

[M Fowler]

I've never found old Fender Bassmans, Tremolux, Deluxes or others of that type to be a mess. The newest SF started getting funky.

Mark

[Structo]

I noticed that too.
Post CBS takeover, they must have fired all the old amp builders and hired new ones.
They also must have got a good deal on wire too because they sure used a lot of it in the silverface amps.

Looks like hay wire in most of them.

You also find a few pig tails in there in an effort to kill oscillations.
They wouldn't dare try good lead dressing to cure it.

[img1920]http://mytubeaudio.files.wordpress.com/ ... mg8783.jpg[/img]

[alanp]

Pardon the newb question, but what was the original reason for the capacitors hanging off the mains AC in?

(Not to mention no earth wire in the original design, but I'm chalking that up to American power plugs.)