TahoeMike00
194 posts
Aug 16, 2013
3:12 PM
|
I have a '91 RI, as to which I am not the original owner, with blue frame Alnico speakers in it. I had it listed on ebay, but it was pointed out to me (by none other than Sonny Jr.) that something was amiss with the way the speakers were wired. In short, there are only 2 wires going to each speaker, he says it's supposed to be 2 pair (4 wires) to each speaker with spade lugs. Mine are soldered. Do you think these speakers were installed after original issue? Or just re-wired for whatever reason? (The "8 OHM trans" Dymo label makes me wonder too)
I have since pulled the listing until I figure out what is up.
Hopefully this picture insert works:
----------
The more I learn about harmonica, the more I learn how much more there is to learn.
Last Edited by TahoeMike00 on Aug 16, 2013 4:39 PM
|
Rick Davis
2231 posts
Aug 16, 2013
3:36 PM
|
Here is my 1991 Bassman RI. When I got it the speakers and wiring were stock. I replaced the bottom two speakers with the Lil Buddys, but did not change the wiring.
The Bassman should have four 8 ohm speakers but the amp is expecting to see 2 ohms, so the label on your amp is confusing.
----------
-Little Rick Davis
The Blues Harp Amps Blog
The Mile High Blues Society
Tip Jar
Last Edited by Rick Davis on Aug 16, 2013 3:43 PM
|
1847
982 posts
Aug 16, 2013
3:37 PM
|
speakers connect to the chassis by way of 4 separate speaker inputs.
the bassman is wired in parallel
each speaker gets tow wires each
----------
master po
i get a lot of request when i play
"but i play anyway"
Last Edited by 1847 on Aug 16, 2013 3:37 PM
|
1847
983 posts
Aug 16, 2013
3:40 PM
|
rick did you add the L bracket ?
----------
master po
i get a lot of request when i play
"but i play anyway"
|
Rick Davis
2232 posts
Aug 16, 2013
3:42 PM
|
1847, Yes, Bruce Collins did the work on the amp.
----------
-Little Rick Davis
The Blues Harp Amps Blog
The Mile High Blues Society
Tip Jar
|
Rick Davis
2233 posts
Aug 16, 2013
3:46 PM
|
TahoeMike, you definitely have a different speaker wiring harness. Do you have a photo showing what the other end of the speaker wires connect to? Does it look like what you see in the photo of my amp?
----------
-Little Rick Davis
The Blues Harp Amps Blog
The Mile High Blues Society
Tip Jar
Last Edited by Rick Davis on Aug 16, 2013 3:47 PM
|
Rick Davis
2234 posts
Aug 16, 2013
3:49 PM
|
I think I get it..... The label might mean the amp has a replacement OT that drives 8 ohms instead of 2. The speakers are wired in series-parallel to get an 8-ohm load. Does that seem right?
----------
-Little Rick Davis
The Blues Harp Amps Blog
The Mile High Blues Society
Tip Jar
Last Edited by Rick Davis on Aug 16, 2013 3:50 PM
|
1847
984 posts
Aug 16, 2013
3:57 PM
|
i have the same bracket installed
----------
master po
i get a lot of request when i play
"but i play anyway"
|
TahoeMike00
195 posts
Aug 16, 2013
4:28 PM
|
Here are a few more pics:
Interesting that there is a (orange) wire that is labeled 2 OHMS, but it is taped off and not connected to anything.
----------
The more I learn about harmonica, the more I learn how much more there is to learn.
Last Edited by TahoeMike00 on Aug 16, 2013 4:30 PM
|
Rick Davis
2235 posts
Aug 16, 2013
4:39 PM
|
Yep, a replacement transformer wired for 8 ohms. That is odd. Not sure why they didn't use the 2 ohm tap and the standard speaker wiring.
If I saw this on eBay I'd pass on it. It looks kind of like a hack job.
BTW, I think what Sonny Jr. meant was there should be four individual pairs of speaker leads coming out of the chassis, as you can see in the photo of my amp.
----------
-Little Rick Davis
The Blues Harp Amps Blog
The Mile High Blues Society
Tip Jar
|
TahoeMike00
196 posts
Aug 16, 2013
5:26 PM
|
Well, frack. It does to appear to have been "reworked" - do you think it would be worth it to rework and get it back to the original wiring setup?
Any resources of schematics or wiring diagrams available for reference?
----------
The more I learn about harmonica, the more I learn how much more there is to learn.
|
tmf714
1896 posts
Aug 16, 2013
5:51 PM
|
Here is the schematic-
http://support.fender.com/schematics/guitar_amplifiers/59_Bassman_schematic.pdf
|
Rick Davis
2236 posts
Aug 16, 2013
8:21 PM
|
1847, I may be mistaken about that L bracket. I looked at pictures of 91 Bassman RI and some had the bracket. It might be a stock feature.
----------
-Little Rick Davis
The Blues Harp Amps Blog
The Mile High Blues Society
Tip Jar
|
jimr
54 posts
Aug 17, 2013
6:19 AM
|
The market inscription on the chassis suggests there may be an additional unused 2 ohm tap. Look behind the chassis for a coiled wire.
Parallel wiring can be executed without 4 separate speaker wires as follows. One opt lead goes to all the positive speaker terminals sequentially. The other lead goes to all the negative terminals. This is how most boutique Bassman clones are wired.
|
arnenym
175 posts
Aug 17, 2013
7:42 AM
|
Don't worry. The speakers is wired serial/parellell to match a 8 ohm output transformer. If it sound good keep it as it is.
If you want to try parallell speakers, just swap the orange and black/white wire on the speaker jack. Then rewire the speaker to all parallell.
http://cie-wc.edu/Series_Parallel_9_14.pdf
Last Edited by arnenym on Aug 17, 2013 7:45 AM
|
TahoeMike00
198 posts
Aug 18, 2013
10:59 AM
|
Thanks everyone for the replies and schematic links.
@arnenym - thanks for the link to the .pdf on speaker wiring, very helpful.
----------
The more I learn about harmonica, the more I learn how much more there is to learn.
|
timeistight
1324 posts
Aug 18, 2013
11:17 AM
|
"If you want to try parallell speakers, just swap the orange and black/white wire on the speaker jack. Then rewire the speaker to all parallell."
Wouldn't it be dangerous to wire a 2 ohm load to an 8 ohm transformer tap?
Last Edited by timeistight on Aug 18, 2013 11:31 AM
|
arnenym
177 posts
Aug 19, 2013
6:18 AM
|
It is very dangerous to wire a 2 ohm load to 8 ohm transformer tap.
If youre not sure the orange is a 2 ohm Transformer tap - Don't do it.
I see what they have wrote on the chassie and i presume it is a black/White wire sitting on the + connection on the speaker jack.
And the orange marked with 2 ohms.
If you're sure that is correct.
-Put it where the Black/white is now.
And tape the Black/White.
|
