Wednesday, February 25, 2015

West Fillmore amplifier, ultra rare! BEAST!

  Got to restore this crazy piece of hippy history, a West Fillmore 200 watt bass amp. Rare as hens teeth!


I like this amp. It's stupid simple under the hood:





And it has the biggest output transformer I've ever seen on a bass amp! Bigger than an SVT:



Output transformer is ultra-linear and built by the legendary Dynaco. I wonder if they ever used this in a high fidelity amplifier? I'd love to see it.

Amp was blowing fuses. Fortunately it was a simple re-cap job. Transformers are okay. I added a bias pot and some bleeder resistors as well so it now bleeds off those massive filter caps when the amp is off.

Speaking of which, NO USER SERVICEABLE PARTS INSIDE! This baby has 575 volts running around in there. Leave it to the pros to work on. It'll put a massive hurt on you if you slip.

Circuit is pretty primitive by todays standards. It's basically just a big ol' Fender Bassman 100 circuit, just with way more power. Nothing fancy, just plug in your passive pickup loaded bass and enjoy some real warmth and depth in your sound.

Can't help but wonder if there is a way to make a recording of all the bands over the years are locked inside this beast. I don't know anything about this brand but it seems like perhaps it was built for the Fillmore West? Could be dead wrong about that. But either way, this amp makes me wanna play a Fender Rhodes!

JB










I like this amp. It's stupid simple under the hood:

8 comments:

  1. thanks for this post. I have a West Grande I bought in 1994. Still my favorite bass amp. Used to have the matching 2-12 EV SRO cabinet, but got stolen 15 yrs ago. Would you happen to have schematics for the Grande and Fillmore? I'd like to build a Fillmore clone.

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    1. That's awesome! I'd love to see someone do it. I loved Mel's bass tone. The only drawback to me is that They are at least as heavy as an SVT & with both trannies on one end! A "real man's" amp. What specifically did you like about the Grande? Is this 100 watt model enough power to play live?

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    2. Very late reply! I found a schematic by Googling it. Let's see if this link works:

      http://i.imgur.com/cslInIU.jpg

      https://www.reddit.com/r/tubeamp/comments/4abe38/west_amplifiers_fillmore_schematic/

      It appears the Grande is similar, just with a smaller transformer and 2 output tubes. Hope this helps! J

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  2. Fender Bassman huh? I had a vintage 70's Bassman 100, but I thought the West was supposedly built like a Sunn, which was also based on a Dynaco circuit............

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  3. Nope! Look up the schematic. 12AT7 driver / phase inverter rather than 6AN8 like Sunn or Dynaco. Thanks for chiming in! J

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  4. Thanks for responding, Jeff. Does this effect the response of the amp? One thing I didn't like about Sunns is the fast, stiff, immediate response, although I LOVE the deep thick low end. Are West similar in feel? Also, The Sunn 2000S & West Fillmore were both stock w 4 KT88's. Yet there was supposedly a big difference in power. How do the 2 amps compare? Thanks

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    1. Hmmm, I wrote this so long ago that my memory is foggy. I do seem to recall it being not as refined as a Sunn Model T or a 2000S, but definitely with a thick low end. Power wise they were similar. Rated at around 200 watts I believe it only really did around 150w. Of course with real KT-88 tubes it may get to 200. Unfortunately I didn't record notes when I had it! It was definitely exciting as I had never seen one and probably will never see another and I don't really work on the big amps any more. I know it belongs to a studio and they use it for bass and occasional keyboards.

      Funny thing is the more research I do about these, the more I realize they may have been intended for use as a guitar amp! Not unusual as Park had their 150 and Marshall had their Major. Different times! Permanent hearing damage required to play rock n' roll!

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  5. Interesting. I just love vintage tube amps, especially the ones with huge bottom end. From reading about what Dave West said about how he got the ideas to make them, what you've said & other research, with my VERY limited knowledge re:amps, I'm thinking Sunn power circuit w Fender preamp circuit. Thanks for the schematic. I'm sure it will be helpful to some who want to try & build one, but I'm "electronically illiterate, LOL!

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