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Post subject: Can anyone help me date this Bassman 10?
Posted: Sat Sep 10, 2011 10:52 am
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I have a friend who has a Bassman 10 Silverface and we'd like to know what year it is but have been searching online for a good while with no luck.

The number stamped on the chasis is A904483. It runs, from left to right, 2 6L6GC tubes, 1 12AT7 and 2 7025's

Also, another question we had was that on this amp, for some reason, the ON switch changes function sometimes. Like sometimes you flip it up to turn it on and sometimes you will have to flip it down, which isn't consistent.

Also, the 6L6GC tubes are pretty old and he would like to get new ones. We were looking at the Ruby tubes on Mucisians Friend. Would these work good with this amp? He uses it to play the Bass.

Any help will be truly appreciated!


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Post subject: Re: Can anyone help me date this Bassman 10?
Posted: Sat Sep 10, 2011 11:59 am
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The date range on that style amp is 1967 to 1983. In your serial number, the A+9 = 1979.

[ verify here: http://www.superiormusic.com/page195.htm ] and scroll down to the 1970 to 1989 chart.

The tubes that you have mentioned are excellent for the purpose because they are made for music amplifier use and have more sturdy internal element mounting locations than the same tubes used for older TV or radio chassis. From personal experience in the late 1960's, in order to produce the best quality sound, the 6L6GT's should probably be replaced as a matched pair. These pairs are tested for nearly identical electronic signal processing and is the best way to go in a dual tube output stage.

The Tung-Sol brand 6L6GT's are not as pricey as some and do an excellent job... check here:

http://www.vacuumtube.com/guitartubes.htm


The on/off switch situation sounds as if the slide switch itself is hanging up the contacts internally due to years of wear plus contact arcing and pitting. If the contacts hang up and you slide the switch the other way, the vibration of that plastic button being moved may work the contacts loose and make it seem like the switch works both ways. If I remember correctly, it is only a single pole single throw slide switch, and it should be replaced with one capable of handling 15 amps. The other possibility is that someone replaced it already with a single pole double throw - center off - style switch and wired it so CENTER position is off and both throws are hot. Inspect it to see what's in there but UNPLUG IT and wait 30 minutes for the power supply filter capacitors to discharge. There's upward of 350 volts DC in that amp and it isn't friendly to those who have never worked on tube circuits before.

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Post subject: Re: Can anyone help me date this Bassman 10?
Posted: Sat Sep 10, 2011 11:52 pm
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The Bassman 10 uses a pair of SP/ST Carling toggle switches located on the amp's rear panel (one for "standby", one for "on")......

Image

These switches are typically rated for 4A-125V/2A-250V and can be easily found on Ebay for less than $10. It sounds like the contacts within the amp's original switch are pitted from age and use and ready for replacement. Consideration should be given to replacing them both since they're likely the same age and probably both just as tired. As PD mentioned, use caution working in and around an exposed chassis and discharge the filter, bias, and "death" caps before proceeding (the death cap should in fact be removed altogether for safety's sake -- with a 3-conductor grounded power cable installed, the cap is totally redundant).

Best of luck, HTH

Arjay

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Post subject: Re: Can anyone help me date this Bassman 10?
Posted: Sun Sep 11, 2011 1:16 am
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Thank you SO much guys. Lots of great info.

Will order the tubes and switch but we're gonna have an expert replace the switch so it doesn't turn into a sour experience.


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Post subject: Re: Can anyone help me date this Bassman 10?
Posted: Mon Sep 12, 2011 5:16 am
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Retroverbial wrote:
The Bassman 10 uses a pair of SP/ST Carling toggle switches located on the amp's rear panel (one for "standby", one for "on")......

These switches are typically rated for 4A-125V/2A-250V and can be easily found on Ebay for less than $10. It sounds like the contacts within the amp's original switch are pitted from age and use and ready for replacement. Consideration should be given to replacing them both since they're likely the same age and probably both just as tired. As PD mentioned, use caution working in and around an exposed chassis and discharge the filter, bias, and "death" caps before proceeding (the death cap should in fact be removed altogether for safety's sake -- with a 3-conductor grounded power cable installed, the cap is totally redundant).

Best of luck, HTH

Arjay



Arjay - good to see a photo in detail in your post. It's been awhile since I saw one up close and the last one I saw about 20 years ago actually had the standby switch on the back (to power the tube heaters without B+ to the tubes, if I remember correctly) and the main on/off switch had been moved to the front panel by someone. I suggested 15 amp contact ratings because the heavy duty switches are physically almost the same size as the 4 amp version, but the heavy contacts inside would not be affected as much by the initial power surge into the transformer, bridge rectifier and filter capacitor circuit and contact pitting might not be a problem with heavier rated switches.

Thanks again for the photo - brings back memories of the days playing in cold venues and warming our hands on the back of the amps between sets...LOL...

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Post subject: Re: Can anyone help me date this Bassman 10?
Posted: Mon Sep 12, 2011 11:43 pm
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Here is the correct switch for your amp......

http://www.ebay.com/itm/Fender-SPST-Tog ... 19c8d1a0ff

HTH

Arjay

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"Here's why reliability is job one: A great sounding amp that breaks down goes from being a favorite piece of gear to a useless piece of crap in less time than it takes to read this sentence." -- BRUCE ZINKY


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