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Post subject: NAD - Non Fender
Posted: Mon Apr 08, 2013 4:56 pm
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Just bought a Bogen Challenger CHA-33 that I'll be converting to a guitar amp head over the next few weeks - should be fun. Pictures coming shortly.

Apparently these old PA amps may be a fun place to start tinkering - many are under $250 - how many pre 1965 amps can you say that about? Of course, I know there will need to be parts updated, etc. but should be a fun experiment. Looking forward to driving the Tremolux cab with it this summer!

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'59? Bogen Challenger CHA-33, '65 Bandmaster, '65 Tremolux, 65 Showman;
'74 SF Princeton; '77 SF Princeton Reverb; Dr. Z Mini Z

Our band: http://www.facebook.com/thetoysband


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Post subject: Re: NAD - Non Fender
Posted: Tue Apr 09, 2013 9:18 pm
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here's an image:

Image

33 watts, 6L6, dual tube rectifiers, made around 1958. Can't wait to get it and take more "before" pictures.

Suggestions?

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'59? Bogen Challenger CHA-33, '65 Bandmaster, '65 Tremolux, 65 Showman;
'74 SF Princeton; '77 SF Princeton Reverb; Dr. Z Mini Z

Our band: http://www.facebook.com/thetoysband


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Post subject: Re: NAD - Non Fender
Posted: Wed Apr 10, 2013 5:23 am
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The architect in me is showing...... but I love the perforated metal and the "Challenger" logo design.


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Post subject: Re: NAD - Non Fender
Posted: Wed Apr 10, 2013 6:07 am
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Me too - it's super clean for its age. More pics as I get it and as my friend who overhauled my Showman updates this.

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'59? Bogen Challenger CHA-33, '65 Bandmaster, '65 Tremolux, 65 Showman;
'74 SF Princeton; '77 SF Princeton Reverb; Dr. Z Mini Z

Our band: http://www.facebook.com/thetoysband


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Post subject: Re: NAD - Non Fender
Posted: Tue Apr 23, 2013 9:50 pm
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Just arrived today from eBay - 6L6GB x 2, mine is the single 5U4GB rectifier, 33 watts. may turn the Phono control into a master volume.

Flickr photo set link:
http://www.flickr.com/photos/67163340@N03/sets/72157633312616843/

More to come! If someone has the schematic for the later model here that has the 1 5U4GB rectifier instead of the 2x 5Y3GT, that would be great. I've been combing through google (and Bogen) and can only find the earlier 2 rectifier model. Agree that there will need to be some modding to make this work for guitar, but have heard some good examples on YouTube. Tweed Deluxe would be a nice sound and would go well with some clean BF Fenders...!

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'59? Bogen Challenger CHA-33, '65 Bandmaster, '65 Tremolux, 65 Showman;
'74 SF Princeton; '77 SF Princeton Reverb; Dr. Z Mini Z

Our band: http://www.facebook.com/thetoysband


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Post subject: Re: NAD - Non Fender
Posted: Wed Apr 24, 2013 5:41 am
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Aspiring Musician
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Yikes on the delivered package looks like it was a prop in an old American Tourister commercial.

These types of projects are just freaking cool. The local shop owner has been doing the same with some of his older audio equipment. I've only done the re-purposing of old movie/pa speakers, which only involves adding the proper input jack.

I look the inventory tag.

Looking forward to the finished product.


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Post subject: Re: NAD - Non Fender
Posted: Wed Apr 24, 2013 7:51 am
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I'm talking to the seller Sunday to walk through powering it up to ensure none of the tubes were damaged in transit - nothing broken, but just in case as they were all NOS Bogen labeled Mullards or RCAs. He had already replaced the filter cap cans, so there may be less to get this up and running (he was using it as a guitar amp).

Before modding the inputs, anyone know where I can get that kind of mic connector to make a 1/4" adapter?

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'59? Bogen Challenger CHA-33, '65 Bandmaster, '65 Tremolux, 65 Showman;
'74 SF Princeton; '77 SF Princeton Reverb; Dr. Z Mini Z

Our band: http://www.facebook.com/thetoysband


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Post subject: Re: NAD - Non Fender
Posted: Mon Apr 29, 2013 2:23 pm
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Just wired up a cheap guitar cable to an Switchcraft F-type connector and some speaker wire to a Carvin cab to the common and 8 ohm terminals in the back.

Sounds very nice! the impedance is slightly off for instrument vs. microphone, but nothing a few values can't change. tubes are all healthy and both mic inputs work great. Same with treble and bass response - will need to be tweaked for guitar. Still stunned that after the box arrived looking like a prop from an American Tourister ad that it works, but it's a testament to 1950/60's build quality.

Will probably look into making the "phono" pot into a master volume, either pre or post phase inverter. I know the Dr. Z amps are post phase inverter; is there a difference in the sound or benefit one way or another?

thanks!

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'59? Bogen Challenger CHA-33, '65 Bandmaster, '65 Tremolux, 65 Showman;
'74 SF Princeton; '77 SF Princeton Reverb; Dr. Z Mini Z

Our band: http://www.facebook.com/thetoysband


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Profile
Post subject: Re: NAD - Non Fender
Posted: Sat May 04, 2013 4:36 pm
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Those old Bogen PAs were tough boxes. Should be a fun project. I think at one point in time, every public school in the country had at least one Bogen or RCA PA. Usually a multi-channel for the auditorium and single channel for the gym.

It's ok non-Fender. Leo started out fixing PA amps. :D

Art


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Post subject: Re: NAD - Non Fender
Posted: Sat May 04, 2013 7:19 pm
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nedorama,

Amp is in great shape. Esp for a PA amp.

Just an FYI... those are Russian made (Reflector or Kaluga) 6L6GB's. The solid saucer-shaped getter rings are a trademark of all Russian made tubes. They are usually good tubes, if you keep the plate voltage under 425VDC and the output around 19 watts per tube.

The rectifier is an RCA 5U4GB.

Be interesting to see the guts. The last Bogen I redid had truly point-to-point circuitry.

Good luck with the amp!


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