Kenwood ka1400 vintage 1974 a question

bigtuna

bigtuna

Well-Known Member
This little amp is truly amazing. , crystal clear sound, but. The old style speaker connector "machine screws" . And I was using bare wire, yes... a no no , one wire pulled off shorted out the b side of the a and b speaker selector. Now my question there's 3 fuses on the inside would one possibly be for this. Or would it likely be a fried output transistors, any thoughts. Thank you all. Oh the a side still works fine I'd still like to xix the b side, and I'm making new speaker wires with proper connectors
 

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The situation is a bit unclear to me.

A and B represent positions of the speaker switch, not channels. A is for one pair of speakers, and B is for a second pair of speakers. The A terminals have two pairs of connections...R+, R-, L+, L-. Same for the B terminals.

When you say the A side is working fine, do you mean that you have a pair of speakers connected to the A terminals (Left and Right)?

BTW, this amp puts A and B in series. Were you using only one pair of speakers, with one connected to A and one to B? With selector set to A+B?
 
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OK on the a position there is a place for a left and right speaker, also on the b position there is a place for a left and a right speaker, , I was using the b position now the b side is fried, no sound, the a side sound is working 100%, both speakers.
 
Yes I have ran them on a and be , previously worked fine on a+b. But now only a works on a + b
 
bigtuna said:
Yes I have ran them on a and be , previously worked fine on a+b. But now only a works on a + b
Click to expand...
I'm still confused. You say that it previously worked on a+b, but now only works on a+b. So what is the problem?

If the amp is operating correctly, these are the possible scenarios:
  1. One pair of speakers connected to the A terminals, speaker selector in A position In this scenario, speakers will play correctly. Note that if the selector is in the B position or A+B position, the speakers will not play.
  2. Two pairs of speakers, with one pair connected to the A terminals and one pair connected to the B terminals:
  • Selector on A - the A speakers play
  • Selector on B - the B speakers play
  • Selector on A+B - both pairs of speakers play
3. One pair of speakers, connected to the B terminals. This will work only when selector is set to B.​
​
The fact that the amp is working fine with a pair of speakers connected to the A terminals tells you that there is not a problem with your output transistors.

This amp will work with the selector in the A+B position only when speakers are connected to both the A and B terminals. This is because, as I mentioned previously, this amp places your speakers in series when the selector is in the A+B position. Many kenwood amps and receivers are designed this way. Less common with the other mainstream brands.

The amp was designed this way to protect it from low-impedance loads. The downside is that running two pairs of speakers in series will compromise sound quality (unless all four speakers are the same make and model), and it reduces maximum output of the amp by half. Reducing the maximum output reduces headroom (power available for transient peaks in the music), thereby increasing the likelihood of clipping distortion unless you are running very sensitive speakers.
 
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I had a speaker wire come off and shorted out the B side. I don't know how else to explain it, but a buddy has just messaged me saying that the three fuses one for the main power one for the A side and one for the B side. Now I know where to look when.i go in there. , should be a no Brainerd, ill let you know, but thank you for the quick reply
 
Oh yes also I know it has to have a speaker connected to a and a speaker hooked up to b as well, yes I was running it that way when it shorted out. , so after this I hooked up both speakers to a and yes it works fine, on the a side,
 
Crimp some spade lugs on the ends of your speaker wires. Save yourself grief!

Your speakers are left and right, not A and B. A and B are PAIRS of left and right speakers. if you have indeed shorted one side (left or right) it's likely you blew the output transistors unless this is a cap coupled amp. Don't have a schematic handy to see if you have speaker protection fuses.
 
Kwade... yes I have hooked them up and ran them all 3 ways you are talking about, both speakers on a both on b and one on a and one on b. All 3 modes worked flawlessly until one of the speaker wires came off and shorted on one of the p connectors.
 
HPMguy said:
Crimp some spade lugs on the ends of your speaker wires. Save yourself grief!

Your speakers are left and right, not A and B. A and B are PAIRS of left and right speakers. if you have indeed shorted one side (left or right) it's likely you blew the output transistors unless this is a cap coupled amp. Don't have a schematic handy to see if you have speaker protection fuses.
Click to expand...

OP says it is working fine with speakers connected to the A terminals, which eliminates blown outputs as a problem.
 
Would almost have to be a switch problem if they don't both work on B then.

If this amp puts the speakers in series for right and left when set to A+B, you must have a speaker connected to both A and B terminals, otherwise neither side is connected
 
Working 100% now. A B AND A AND B

THANK YOU ALL , just pulled every fuse , blew out all the dust,
 
HPMguy said:
Would almost have to be a switch problem if they don't both work on B then.

If this amp puts the speakers in series for right and left when set to A+B, you must have a speaker connected to both A and B terminals, otherwise neither side is connected
Click to expand...
As mentioned above, it does put A and B in series.
 
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