60wpc Kenwood Underpowered?

RedbowTies88

Well-Known Member
Hi guys, I recently picked up a Kenwood Ka-601 local for $25. It was in desperate need of a cleaning and some Deoxit but other then that, one broken switch post, and ALL FOUR nuts holding down the transformer coming loose it was in good shape.

The problem is it just seems way underpowered for a 60 watt amp. The Kenwood with the volume knob at 3o'clock is about equal to my SX-750 at 12o'clock and my Sansui 7070 at around 11o'clock.

Does that seem normal? I'm afraid to go any post that position for fear of clipping the amp and damaging my speakers. The only other concern I had was that I can't tell if the DC coupling switch is working. IT doesn't seem to have an effect on the sound. Should there be a drastic or at least noticeable change when it's on?

Thanks.
 
That's not really power, per se, but is a lack a of gain. That is to say this it isn't amplifying as ti should be. On the other side of the situation the volume control position isn't really an indication of the power either. It could simply be that the amp's sensitivity is lower and requires more gain for the specified power output.

The only way to know is to verify its performance with a scope, simulated load and signal generator. Now, if there is DC on the output, this can be verified with a multimeter set to VDC and testing the output when the amp is idling.
 
If it works like some other coupling switches, about all it does is remove a capacitor between the input jacks and the amplifier circuits. I'm not really a fan of this since it would allow for a poorly behaved preamp to cause some problems.
 
That's not really power, per se, but is a lack a of gain. That is to say this it isn't amplifying as ti should be. On the other side of the situation the volume control position isn't really an indication of the power either. It could simply be that the amp's sensitivity is lower and requires more gain for the specified power output.

The only way to know is to verify its performance with a scope, simulated load and signal generator. Now, if there is DC on the output, this can be verified with a multimeter set to VDC and testing the output when the amp is idling.

Ok good to know, perhaps it just requires more use of the volume pot to get to the needed level. I have about a dozen vintage receiver but this is my first integrated amp from that era. Perhaps it's just supposed to be that way.

If it works like some other coupling switches, about all it does is remove a capacitor between the input jacks and the amplifier circuits. I'm not really a fan of this since it would allow for a poorly behaved preamp to cause some problems.

Should there be any kind of change in volume or sound though? I guess features sell amps but if the difference isn't even noticeable by someone with better then average ears then why bother?
 
Whatever speakers the OP has, KA-601 is as good as SX-750 or Sansui 7070 to power them. Possibly better.

As far as volume control goes, it is supposed to be that way.

Input sensitivity (line):
Kenwood KA-601 - 200mV
Pioneer SX-750, Sansui 7070 - 150mV

This alone means that even if you had exactly the same circuits in all three amps from the input on, you would have to turn the volume knob more on the amp that has 200mV input sensitivity. And volume pot curves vary too. Some pots have most gain from 7 to 10 o'clock, some (and that's better for normal use) from 12 to 3 o'clock.

If you have two 60 WPC amps one with input sensitivity 150 mV the other with 200 mV, the 150 mV amp will get to it's rated power faster. And then it will start clipping. If you use a 2xxx series Marantz with a CDP and a loud CD, it will be at full power with volume pot at 1-2 o'clock. You can go louder, but the sound will be distorted and ultimately you will blow your amp, speakers, or both. If you use an amp with same power but different input sensitivity, the top amount of clean power you get out of it will be the same, but it will be at a different volume pot position.


DC coupling switch should not have a drastic effect on sound. Whether it would be noticeable at all depends on the rest of your system and on your source material. It should be audible on very good speakers or headphones, on average ones, not so much. And the difference, if any, should be mostly in accuracy, clarity, detail and soundstage, not in tonal balance and volume.
 
Quick question....

Is the attenuator switch (right of the volume control) working, and what position is it?
 
I haven't dug up the manual but 60 watts (or the amp overall amperage in watts) is probably the peak out spike for the amp..

It's not a barn stormer..
 
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