1967 "Fender" Double Bassmaster Custom Amp

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xtian
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1967 "Fender" Double Bassmaster Custom Amp

Post by xtian »

Double Bassmaster Custom Amp!

I traded for it. Guy said his military uncle picked it up overseas. Search Google for "Double Bassmaster Custom Amp". There are no hits. Not even with "Double Bassmaster". This amp is an odd duck.

Components are nice. Schumacher PT (1966), Stackpole pots (1966), Mallory eCaps and brown molded tone caps. And the lead dress is lovely--look at those ground busses.

The aluminum chassis screams hand made. Look at those pine end caps. Hand stamped with serial CMS126.

Circuit looks like Bassman AA864.

Came with a HUGE 2x15 speaker cab.

More details after I have a chance to fire it up.
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Last edited by xtian on Tue Feb 14, 2017 8:47 pm, edited 1 time in total.
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more photos

Post by xtian »

more photos
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xtian
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Re: 1967 "Fender" Double Bassmaster Custom Amp

Post by xtian »

Powered up, and all functions good! Played just a bit with bias set lowest possible, seeing if any bugs. Seems fit as a fiddle, pretty decent for a 50-year-old!
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Re: 1967 "Fender" Double Bassmaster Custom Amp

Post by dcribbs1412 »

Nice!
Is there a Dumble or any signature somewhere? :D

D
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xtian
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Re: 1967 "Fender" Double Bassmaster Custom Amp

Post by xtian »

No signatures, initials, dates, or quality control stickers. 8)
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Re: 1967 "Fender" Double Bassmaster Custom Amp

Post by ToneMerc »

xtian wrote:Double Bassmaster Custom Amp!

I traded for it. Guy said his military uncle picked it up overseas. Search Google for "Double Bassmaster Custom Amp". There are no hits. Not even with "Double Bassmaster". This amp is an odd duck.

Components are nice. Schumacher PT (1966), Stackpole pots (1966), Mallory eCaps and brown molded tone caps. And the lead dress is lovely--look at those ground busses.

The aluminum chassis screams hand made. Look at those pine end caps. Hand stamped with serial CMS126.

Circuit looks like Bassman AA864.

Came with a HUGE 2x15 speaker cab.

More details after I have a chance to fire it up.
Vietnam era "serviceman" knock off amp maybe.

TM
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M Fowler
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Re: 1967 "Fender" Double Bassmaster Custom Amp

Post by M Fowler »

Yes there have been a few others posted on forums as well, this one looks the best of all the ones I have seen.
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Post by Stevem »

There was a Twin reverb like this in Vintage guitar Mag some 2 or 3 years ago and if I recall right it was made in either Japan or the Philipeens!
When I die, I want to go like my Grandfather did, peacefully in his sleep.
Not screaming like the passengers in his car!😊

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Re: 1967 "Fender" Double Bassmaster Custom Amp

Post by xtian »

The circuit in this amp is very close to AA864, except for this part of the Bass channel, between the Volume pot and next gain stage.

Must be tone shaping? I mean, I recognize the 1n || 470K as a treble peaker, then we've got the .05u coupling cap and 1M grid reference. But what about that .25u cap and 4K7?
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Re: 1967 "Fender" Double Bassmaster Custom Amp

Post by pompeiisneaks »

I think that's just a two stage filter, if they're in series it's called a second-order high pass filter, this is just two coupled high pass filters, no? I think you could see that it's likely notching two separate frequencies in a fixed way.

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Re: 1967 "Fender" Double Bassmaster Custom Amp

Post by xtian »

Had a chance to check out the 2x15, 4-ohm cab that came with. Sounds awesome! Four-inch aluminum dust caps...wonder what speakers are hiding in there. But there are five THOUSAND screws holding the back panel in pace...

Aw, heck. You know I'll open it up.
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Re: 1967 "Fender" Double Bassmaster Custom Amp

Post by xtian »

Just for my records, some date codes:

pots are Stackpole: 304-6504 and 304-6635

PT is Schumacher: 18P154A, 606 620
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Post by Stevem »

4" dust caps to me speak of a 328 manufacturer code I will guess!
When I die, I want to go like my Grandfather did, peacefully in his sleep.
Not screaming like the passengers in his car!😊

Cutting out a man's tongue does not mean he’s a liar, but it does show that you fear the truth he might speak about you!
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Re: 1967 "Fender" Double Bassmaster Custom Amp

Post by xtian »

40 screws later, I had the back off the 2x15 cabinet.

Back of magnets marked:

U 2015
67 7451

Paper cone marked with: W5556

(Plus bonus sticker with 9955 Woodruff)

So...can we get a manufacturer code out of that?
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Re: 1967 "Fender" Double Bassmaster Custom Amp

Post by xtian »

I think the OT was NEVER wired properly!

First, I took note of the three output taps, typical of 4/8/16-ohm secondaries. The yellow and orange ones were connected to the Speaker and External jacks, and the green one was connected to the NFB circuit only. Weird.

So I disconnected all OT leads and tested the turns ratios, and my suspicions are confirmed. Yellow is for a 16-ohm load, reflecting 1728 ohms on primary. Orange is 8-ohm/1752, and green is 4-ohm/2080.

So I rewired with 4 and 8-ohm output jacks, and tied off the 16-ohm tap for now.

Now I'm working on replacing the 50-year-old 'lytics. Some of the old tubes were really weak, too, so this should be a whole new machine shortly.
I build and repair tube amps. http://amps.monkeymatic.com
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