This is a review and some measurements of the Marantz SR5000 AV receiver. The unit was about to be thrown away as it was defective and nobody wanted to fix it. I have a friend that needed a decent amplifier and didn't have the budget to buy something, so I thought that I will fix it and give it to him for free. To my surprise, the power amplifier stage was completely blown. Out of 10 final transistors, 7 were blown and many other smaller signal ones as well. As I build amplifiers and other electronics, I had many parts "on stock" so apart from an odd transistor type that I had to get of Aliexpress (genuine parts, of course 
), I had most of the parts in house. After many hours of work and frustration, I managed to fix it and I figured out it is a good opportunity to measure it and post it here. As a side note, even three (out of five) power resistors (0.22ohm) present on the output stage, where fried. These are thick metal stripes internally 
. The device came straight from Japan so it needs 110Vac so I used a 230Vac to 110Vac transformer to power it up.
The unit has the classical AV receiver looks and it was new in the early 2000's. On the back, we have the usual connections and no HDMI as it wasn't standard in the early 2000s.
The FM radio is pretty useless in Romania as it is dedicated to Japan and it goes from 76 MHz to 90 Mhz. I was able to tune one or two stations but that is it. The unit has a built in DAC with optical and coax inputs. I didn't test the internal DAC. If I have the time, I will look at it's performance later.
I use my QA401 analyzer for these measurements and I used an 8OHM resistive load.
I will start with the usual 1kHz test tone at 5W:
I have to say that I'm pretty happy with the performance. The stuff at 50Hz and it's harmonics might be due to the test setup as I was able to decrease these quite a bit. Nevertheless, the figures remained pretty much the same. We have a THD of -87dB and a SINAD of around -80dB. I measure both the only remaining original channel and the ones I repaired and all measure pretty much the same.
Next I had a look at the multitone:
We have -80 to -90dBs of distortion free signal. Not bad!
The device does have tone controls and below we see the frequency response with these in the middle, so in theory no effect.
We see that it's not 100% flat. We have 1 to 2dBs variations depending on frequency, with some extra bass and attenuated lower mids. This can be corrected by the means of the potentiometers but this is the "flat" option. Below we see what maxing bass and treble does to the FR.
We have roughly 10dBs of amplification for both the low and the high end.
Looking at IMD we see good performance with IMD artefacts at around -80dBs:
I tried doing an output power vs THD graph but I got stuck in the QA software and was not able to get correct results. Instead, I went as high as I could go until distorsion jumpped.
That is almost 77W and THD+N remaine well controlled at -81dB. This is pretty good in my view.
The spec of the device lists 70W per channel and a THD of 0.09% and I measuted 77W, a THD of 0.0049% and a THD+N of 0.01%. This is considerably better than the spec, so this is a good surprise.
The listening impressions were pretty good as well. The sound is OK, as seen from the measurements, and I think it will make for a great amplifier for my friend. Did it make any sense repairing it? No, probabbly not as it needed many high power transistors and many hours of my time. Commercially it did not make any sense to repair but in this particulat case, it made sense as it will be used by a firend of mine for many yeas to come (hopefully).
), I had most of the parts in house. After many hours of work and frustration, I managed to fix it and I figured out it is a good opportunity to measure it and post it here. As a side note, even three (out of five) power resistors (0.22ohm) present on the output stage, where fried. These are thick metal stripes internally . The device came straight from Japan so it needs 110Vac so I used a 230Vac to 110Vac transformer to power it up.The unit has the classical AV receiver looks and it was new in the early 2000's. On the back, we have the usual connections and no HDMI as it wasn't standard in the early 2000s.
The FM radio is pretty useless in Romania as it is dedicated to Japan and it goes from 76 MHz to 90 Mhz. I was able to tune one or two stations but that is it. The unit has a built in DAC with optical and coax inputs. I didn't test the internal DAC. If I have the time, I will look at it's performance later.
I use my QA401 analyzer for these measurements and I used an 8OHM resistive load.
I will start with the usual 1kHz test tone at 5W:
I have to say that I'm pretty happy with the performance. The stuff at 50Hz and it's harmonics might be due to the test setup as I was able to decrease these quite a bit. Nevertheless, the figures remained pretty much the same. We have a THD of -87dB and a SINAD of around -80dB. I measure both the only remaining original channel and the ones I repaired and all measure pretty much the same.
Next I had a look at the multitone:
We have -80 to -90dBs of distortion free signal. Not bad!
The device does have tone controls and below we see the frequency response with these in the middle, so in theory no effect.
We see that it's not 100% flat. We have 1 to 2dBs variations depending on frequency, with some extra bass and attenuated lower mids. This can be corrected by the means of the potentiometers but this is the "flat" option. Below we see what maxing bass and treble does to the FR.
We have roughly 10dBs of amplification for both the low and the high end.
Looking at IMD we see good performance with IMD artefacts at around -80dBs:
I tried doing an output power vs THD graph but I got stuck in the QA software and was not able to get correct results. Instead, I went as high as I could go until distorsion jumpped.
That is almost 77W and THD+N remaine well controlled at -81dB. This is pretty good in my view.
The spec of the device lists 70W per channel and a THD of 0.09% and I measuted 77W, a THD of 0.0049% and a THD+N of 0.01%. This is considerably better than the spec, so this is a good surprise.
The listening impressions were pretty good as well. The sound is OK, as seen from the measurements, and I think it will make for a great amplifier for my friend. Did it make any sense repairing it? No, probabbly not as it needed many high power transistors and many hours of my time. Commercially it did not make any sense to repair but in this particulat case, it made sense as it will be used by a firend of mine for many yeas to come (hopefully).
