It happened to me that I got a Harman Kardon HK 3270RDS stereo receiver into my greedy measurements fingers. The service manual is dated as of 2004 so the unit should be some 15 years old, the owner however thought that it was older which could certainly be true: I found a price of € 450 in 2000-2002 here.
The receiver has some nice features:
Well, we found out soon enough that nothing was broken and the receiver worked without flaws (later my colleague found out that a cable was broken). So with some time left I did a few quick measurements of the preamplifier (I have no proper load yet for measuring the power amp). They were done in a hurry so excuse the different frequency scales please.
Specs are as follows:
Performance is dominated by hum and power supply noise.
Since most CD players emit 2VRMS a redid the test with a 2VRMS sinus and reduced the volume such that the preamp output was at 1VRMS as before:
Unfortunately now harmonic distortion dominates (hum and noise are a bit lower though which is good).
REW offers a multitone test with 16 sinus signals:
I think we have seen worse.
Finally measurement of IMD (CCIF: 19 + 20 kHz sinus):
IMD is not that bad - we see also the power supply stuff to the left.
My colleague had to leave so I could not measure more. So far as I can see the receiver made a reasonable impression to me. No highend of course but nothing broken either.
The receiver has some nice features:
- preamp in and power amp out (bridged by external connection)
- subwoofer out (but no highpass in the stereo outputs)
- loudness control
- balance and tone controls
Well, we found out soon enough that nothing was broken and the receiver worked without flaws (later my colleague found out that a cable was broken). So with some time left I did a few quick measurements of the preamplifier (I have no proper load yet for measuring the power amp). They were done in a hurry so excuse the different frequency scales please.
Specs are as follows:
- Power at 0.08% THD (20 Hz to 20 kHz), both channels driven: 70W @ 8 Ohm and 95W @ 4 Ohm
- THD @ 65W and 8 Ohm, CD input: <= 0.05% nominal at 20 Hz, 1 and 20 kHz
- IMD @ 50W and 8 Ohm: <= 0.05% nominal
- SNR @ 70W, CD input (shorted): >= 100 dB nominal
- Input sensitivity is 200 mVRMS for all line level inputs
- Power consumption 332W (confirms the power output)
- Weight 11.2 kg
Performance is dominated by hum and power supply noise.
Since most CD players emit 2VRMS a redid the test with a 2VRMS sinus and reduced the volume such that the preamp output was at 1VRMS as before:
Unfortunately now harmonic distortion dominates (hum and noise are a bit lower though which is good).
REW offers a multitone test with 16 sinus signals:
I think we have seen worse.
Finally measurement of IMD (CCIF: 19 + 20 kHz sinus):
IMD is not that bad - we see also the power supply stuff to the left.
My colleague had to leave so I could not measure more. So far as I can see the receiver made a reasonable impression to me. No highend of course but nothing broken either.