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Post subject: My Musicmaster Bass Amp Hums...
Posted: Fri Jan 03, 2014 10:07 pm
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I have a 1970 Fender Musicmaster Bass amp that I've been working on. I received it from another gentleman who had trouble with it. I got it to work but the internals have been heavily modified. It sounds good now but I don't like how loud the buzz gets when the amp is cranked up. Currently, you don't have to turn the volume much past 2 and the hum is pretty bad. It gets worst the more you turn the brightness on the treble knob. Is there something I can add to quiet it down? This is what the seller told me when I bought the amp...

"I replaced the filter caps with Illinois Capacitor electrolytics, the poly caps with Spragues, and the ceramic coupling cap with a .022mfd Sprague. The original value of the ceramic coupling cap was .01 and I read that increasing that value gives the amp a little more bottom end."

Attached are some pictures. Please scroll through.
http://www.flickr.com/photos/99856663@N04/11745245783/


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Post subject: Re: My Musicmaster Bass Amp Hums...
Posted: Sat Jan 04, 2014 1:52 am
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" I replaced the filter caps with Illinois Capacitor electrolytics. "


Sometimes, brand new caps fail. I've had several new ones fail recently. I believe that many IC caps and several Sprague ATOM's are now made in China. The tolerances and voltage ratings of some Chinese parts are optimistic, at best.


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Post subject: Re: My Musicmaster Bass Amp Hums...
Posted: Sat Jan 04, 2014 12:04 pm
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Thanks, I'll look into that. I am hoping it's not the transformers. I'd actually like to sell the amp.


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Post subject: Re: My Musicmaster Bass Amp Hums...
Posted: Sun Jan 05, 2014 3:37 am
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Wiring is poor , heater wires must be twisted, many bad wiring dress to fix/ clean , sure this will induce hum . Also check if input shortening jacks have good contact to ground with no guitar cable in.

Is the photo , I see a burn resistor close to the output transformer ? On the terminal lug

About filter caps just read what is residual AC , if good they are ok , if not replace them.


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Post subject: Re: My Musicmaster Bass Amp Hums...
Posted: Sun Jan 05, 2014 7:49 am
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I didn't see the attached photos:

http://www.flickr.com/photos/99856663@N04/11745245783/

I do not think that this is an original Fender made amp circuit. As Stratele described, this is one of the craziest layouts I've seen. Linear setup of components on a terminal strip is a sure way to get EMF interactions.

One of the resistors on this strip looks cooked (one next to the metal oxide--- looks like a 220-ohm, 2% tolerance). And not sure what that screw and nut on the 8-pin socket is all about (middle socket). Sockets are not US made variety. Orange Drops are not stock.

This looks like one of those "Gabby Industry" Fender clones. What is the history of this amp?


Thanks!


Last edited by BMW2002Ti on Sun Jan 05, 2014 8:46 am, edited 2 times in total.

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Post subject: Re: My Musicmaster Bass Amp Hums...
Posted: Sun Jan 05, 2014 8:26 am
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BMW2002Ti wrote:
I didn't see the attached photos:

http://www.flickr.com/photos/99856663@N04/11745245783/

I do not think that this is an original Fender made amp circuit. As Stratele described, this is one of the craziest layouts I've seen. Linear setup of components on a terminal strip is a sure way to get EMF interactions.

One of the resistors on this strip looks cooked (one next to the metal oxide--- looks like a 220-ohm, 2% tolerance). And not sure what that screw and nut on the 9-pin socket is all about (middle socket). Sockets are not US made variety. Orange Drops are not stock.

This looks like one of those "Gabby Industry" Fender clones. Whagt is the history of this amp?


Thanks!


+100

It is not a fender product , japan made IMO


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Post subject: Re: My Musicmaster Bass Amp Hums...
Posted: Sun Jan 05, 2014 9:33 am
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stratele52 wrote:
It is not a fender product , japan made IMO


Japanese pride would not allow them to produce such an absolute piece of crap such as that.

Likely, made in the Philippines.

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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Post subject: Re: My Musicmaster Bass Amp Hums...
Posted: Sun Jan 05, 2014 9:42 am
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Retroverbial wrote:
stratele52 wrote:
It is not a fender product , japan made IMO


Japanese pride would not allow them to produce such an absolute piece of crap such as that.

Likely, made in the Philippines.

Arjay


In those years there are all Japan made Guitar and amp like Teisco guitars .....

I see few of those Japan made amp in '60 and '70 .I never heard about Philippines tubes amp

Sears sold them on the name of Beltone

But I may be wrong !


Last edited by stratele52 on Sun Jan 05, 2014 9:45 am, edited 1 time in total.

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Post subject: Re: My Musicmaster Bass Amp Hums...
Posted: Sun Jan 05, 2014 9:44 am
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Got any pics?

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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Post subject: Re: My Musicmaster Bass Amp Hums...
Posted: Sun Jan 05, 2014 9:52 am
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Stratele, I think Teisco, Japan made some fairly ok products. I've seen some amps --- all point-to-point with good components. They remind me of some of the early Sansui and Luxman audio gear. Good stuff, really.

And some ppl seek their guitars.

http://i217.photobucket.com/albums/cc23 ... enback.jpg

http://i217.photobucket.com/albums/cc23 ... 10/ptp.jpg


Teisco fan site:

http://www.larryjohnmcnally.com/Teisco/


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Post subject: Re: My Musicmaster Bass Amp Hums...
Posted: Sun Jan 05, 2014 10:02 am
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+1


vintageguitaramps.blogspot.ca/2010/09/teisco-10-tube-amp.html


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Post subject: Re: My Musicmaster Bass Amp Hums...
Posted: Sun Jan 05, 2014 10:18 am
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Stratele, those are Matsushita made caps (see the "three-stone creed" manufacturer's code?). Before the company became Panasonic, worldwide. Some of their electrolytic caps are very good. Their oil-in-paper (the era of this amp) had shorter life expectancy when compared to US made caps. But, were known for nice vintage, warm midrange tone.

All those nice wire-wound resistors! Nice!

Thanks, for link.


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Post subject: Re: My Musicmaster Bass Amp Hums...
Posted: Sun Jan 12, 2014 5:33 pm
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I found the problem. It was the input jacks. I knew it.


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Post subject: Re: My Musicmaster Bass Amp Hums...
Posted: Sun Jan 12, 2014 9:14 pm
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Glad the fix was an easy one.

Many years of happiness! :D


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Post subject: Re: My Musicmaster Bass Amp Hums...
Posted: Tue Feb 11, 2014 10:55 pm
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Wow is that the early model that did not have 6v6 tubes? My 6v6 amp has a board layout like most Fender amps not that PTP mess. You said it was heavy modified I guess so. Glad you got it fixed.


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