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Not enough bass for AR3 from Nikko Alpha 220

guiller

guiller

Toscaninichus Australis
My Nikko Alpha 220, a fine sounding power amplifier otherwise, does not get the best bass out of my AR-3's. I've tried other, more powerful amplifiers (the Nikko is rated at 120 wpc in 8 ohms) and the bass is tighter, cleaner. I first thought that the Nikko was not powerful enough. Then I tried a Nikko Alpha II (with the same power rating) and the bass was there! Now I suspect that the Alpha 220 is somehow cutting down the bass, In the rear, there is a switch that commutes between direct and capacitor coupling speaker output. I've never tried the direct output for fear of having a DC component in my speakers. Would it be reasonable to suspect that replacing that coupling capacitor could restore the cutoff bass ? I have a service manual at home and could check the type and rating of the coupling capacitor.

Thanks in advance for any comments or ideas.
 
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I think it would be more reasonable to put the switch to DC mode, do a quick DC offset check and if OK, see if that restores the missing bass.

If the bass comes back wouldn't that give more creedence to the coupling cap theory?
 
whoaru99 said:
I think it would be more reasonable to put the switch to DC mode, do a quick DC offset check and if OK, see if that restores the missing bass.

If the bass comes back wouldn't that give more creedence to the coupling cap theory?
Click to expand...

Thanks for the suggestion: therefore, I understand that if the offset values are within the limits quoted in the service manual, it should be "safe"(!!??) to bypass the coupling capacitor, right? BTW, is my hypothesis reasonable? I could not think of any other factors that could degrade an amp into a high-pass filtering device, but I'm pretty sure there are many!
 
Well, I switched the amp into "direct coupling" mode and the bass is now much better than before! Although I still think that the Alpha II sounds better, now the bass provided by the Alpha 220 is good enough for the AR-3's. I cannot avoid getting amazed by the bass produced by those speakers! So, I guess that from now on I'll set the switch permanently into direct coupling. I hope this is not too risky for the speakers. Is this what people with similar amps (i.e., with a switch that allows for direct output coupling) do?
 
back in the day (well...last year) i picked up an Alpha 440 and thought the bass was somewhat anemic. i discovered the DC switch and flipped it over. might've helped a little but not much. glad it made a noticeable difference for you!
 
guiller said:
Well, I switched the amp into "direct coupling" mode and the bass is now much better than before! Although I still think that the Alpha II sounds better, now the bass provided by the Alpha 220 is good enough for the AR-3's. I cannot avoid getting amazed by the bass produced by those speakers! So, I guess that from now on I'll set the switch permanently into direct coupling. I hope this is not too risky for the speakers. Is this what people with similar amps (i.e., with a switch that allows for direct output coupling) do?
Click to expand...

If this makes a big difference, then I'd suggest there is something wrong with the coupling cap, or what ever is bypassed by the switch.

Normally, DC coupling switches only impact VERY low frequencies, perhaps even single digit frequencies. I'm not familiar with AR-3s, but regardless, I'd be highly skeptical of any meaningful bass down that low.
 
whoaru99 said:
If this makes a big difference, then I'd suggest there is something wrong with the coupling cap, or what ever is bypassed by the switch.

Normally, DC coupling switches only impact VERY low frequencies, perhaps even single digit frequencies. I'm not familiar with AR-3s, but regardless, I'd be highly skeptical of any meaningful bass down that low.
Click to expand...

I agree: the design of the capacitor coupled output probably intends it to act as a subsonic filer (as you implied, it could even have a cutoff frequency of the order of a few hertz, or maybe up to 10 Hz). I could only imagine that components specs drifting with time could have risen that value up into the audible region. This would explain what I've heard. On the other hand, I should take away those coupling capacitors, measure their capacitance and eventually replace them. This is a unit from the late 70's.

Many thanks for your insight.
 
Have one with a Jbl L7 pair, i got a very nice bass response... Pre beta 20 and eq-1 with +6db eq gain enabled the bass response increments awfuly, even with my linn nexus ls250 bass is pretty nice! Did a bass test with the ls250 and surprise they reproduce from 28hz!
 
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