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Post subject: Fender Bassman Reissue Problems
Posted: Sun Jan 23, 2011 7:16 am
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Location: Kalamazoo, MI
Hello again,
I have a 94' Bassman reissue. I bought it off eBay and of course the seller said the amp worked perfectly. Well it doesn't....
I like to work on amps and guitars and have some experience, but am not an electrical engineer.

Whats happening is the amp sounds like multiple speakers are blown. There is a rattling buzzing sound coming from the amp, and my first thought was speakers. I replaced the two lower speakers with Celestion Vin 30's, but could not get a second pair to fit in the top two speaker mountings because there is just not enough room for them. The amp is almost design to fit around those top two speakers... But I did at one point replace all 4 speakers but left the amp loose, sitting on a towel on the two upper speakers. The sound overall improved, but there was still a rattling sound coming from someplace. It' sounds like a fuzzy distorted speaker or speakers....

Anyway, I tried unplugging, one at a time, the two top speakers. At this point it sounds as if 3 of the bassmans speakers are blown. But i'm wondering if it could be something else? I don't have another amp to try the speakers in.

Is there anything I could check in the bassmans circuit that might be causing this fuzzy sounding distortion? The volume is only at 2 and the problem only occurs when I strike an open low "E" string. So it could be a resonance I suppose causing the sound.
I'm just having a hard time believing speakers may be blown? Heck, maybe it's just the cabinet itself rattling? It's very frustrating trying to run down exactly where the fuzz/rattling is coming from.
I did try replacing all the tubes as well.

Also, will it harm the amp if I unplug individual or pairs of speakers (always leaving at least one plugged in of course) while I am trouble shooting?

Any advice from the technically minded would be greatly appreciated.

Thanks!!
-Chris


Last edited by ctyoung on Sun Jan 23, 2011 8:42 am, edited 1 time in total.

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Post subject: Re: Fender Bassman Reissue Problems
Posted: Sun Jan 23, 2011 7:27 am
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get a multi meter and check the resistance on the speakers... you will see if the speekers are blown if the ohmage is different to the rating on the speaker...

if you open up the amp, check for anything thats been burnt out, lose solder joints, if the speakers are blown then that amp must have been driven very hard or it was plugged into the wrong voltage or something...

check the earth of the amp, you can also use a multi meter for this, the earth on the plug should be connected to the chassis of the amp, so test for this...

also have you checked the valves? are they the right valves for the unit?

as long as you have some resistance on the amp it wont cause too much damage... even so, when you are swapping out speakers, dont keep the amp on for too long with speakers missing... it wont damage it initially but will eventually cause some damage if you use it for any long period of time...

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Post subject: Re: Fender Bassman Reissue Problems
Posted: Sun Jan 23, 2011 8:52 am
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Hi And thank you for your help. :-)
Each speaker measures almost exactly the same resistance. Just under 6 ohms each (disconnected).
The tubes are 6L6's and the preamp and phase tubes are 12ax7's. The rectifier tube is a 5AR4.
I have tried replacing all the tubes, one at a time. The amp is well grounded.
After carefully checking the circuit boards and all components, everything "looks" okay.

The speakers are nice and tight and the cushion/ring on the face of the speakers looks prefect.
At this point, I'm really leaning towards the lacquered tweed cabinet. Nothing appears to be loose, but maybe the board the speakers are mounted on is rattling/buzzing cause the lacquer is hard? I'm gonna remove that and check it out.

Any other ideas?

Thank you!
-Chris


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Post subject: Re: Fender Bassman Reissue Problems
Posted: Sun Jan 23, 2011 8:54 am
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Are you talking about a 4x10 bassman combo? Vintage 30's are the wrong speaker...


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Post subject: Re: Fender Bassman Reissue Problems
Posted: Sun Jan 23, 2011 9:13 am
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randini wrote:
Are you talking about a 4x10 bassman combo? Vintage 30's are the wrong speaker...



Yes.
The are the celestion GL10 vin 30's which are a 10" speaker 8ohm speaker. It's just the magnets are to wide to be used on the top of the cab.


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Post subject: Re: Fender Bassman Reissue Problems
Posted: Sun Jan 23, 2011 9:20 am
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Oh ok, I have some of those in a 4x10 combo myself. 2 of those with 2 vintage alnico 10's.


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Post subject: Re: Fender Bassman Reissue Problems
Posted: Sun Jan 23, 2011 11:17 am
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Well, I took the speaker baffle out and checked for anything that might be vibrating. Nothing....
I then took out all 4 speakers and tested each one in a little Line 6 spider amp. All the speakers were blown except for one.
That was pretty disheartening....
I mean come on Fender. A 40 watt amp that was originally supposed to be a bass amp, and with 4 speakers? Yet a guitar player was able to blow the speakers with a Tele? What's not right with that picture....

Thanks guys for your help.
:-)
-Chris


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Post subject: Re: Fender Bassman Reissue Problems
Posted: Sun Jan 23, 2011 11:31 am
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Dang....I've got 2 of the 10" vintage 30's in my Music Man 4x10 and it's 130 watts...how in the world did the amp take out the speakers? Transformer? Ohm mismatch?


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Post subject: Re: Fender Bassman Reissue Problems
Posted: Sun Jan 23, 2011 12:25 pm
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The Celestions were not blown, I was talking about the stock Fender speakers. The Celestions are awesome in the amp, but I can't get 4 of them in it. The magnets are two wide and they won't fit behind the amps chassis. So the best I can do is put two of them in the amp in the bottom and just deal with one blown speaker up top behind the chassis.
I decided to just put all the original speakers back in the amp and sell it cheap on eBay. I mention in the add that 3 of the speakers are blown....


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Post subject: Re: Fender Bassman Reissue Problems
Posted: Sun Jan 23, 2011 11:45 pm
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sounds strange... if the amp had been run that hard then the speakers blowing up might have caused some damage to the transformers... which is likely what you are experiencing now... id suggest taking it to a tech and checking the board... otherwise... ppl can sell sand on ebay so... a bassman should sell...

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Post subject: Re: Fender Bassman Reissue Problems
Posted: Sun Jan 23, 2011 11:52 pm
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da rok wrote:
if the amp had been run that hard then the speakers blowing up might have caused some damage to the transformers.


I concur. Some rump-swab deliberately abused that amp.

Sad......

Arjay

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Post subject: Re: Fender Bassman Reissue Problems
Posted: Mon Jan 24, 2011 4:28 pm
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once i had some sound that seems alike with what you've described. the only difference - i have a hrdlx II. we played at some stadium around 12:00 AM in front of the sun. the solder joint has gone loose due to heat during our last song. sounded like a blown speaker to my ears onstage. came back home, opened the amp and saw hanging capacitor with no solder. look for smth similar there.


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