Mitsubishi DA-P20 Preamplifier Measurements

[tomtoo]

I dunno, the emerald green seems a bit overwhelming and is clashing with the deep red of the frequency display. This is not an easy one, and the stock choice of moderately bright warm white may be hard to beat, but what about, say, a nice amber?
View attachment 449682
('Shop for illustration purposes.)

BTW, this is another analog tuner with a grid-locked oscillator, like some Pioneers of the time. The high selectivity and low phase noise of a mechanically-tuned frontend (and I imagine nice weighted flywheel tuning at that) with the frequency stability of a PLL synthesizer.

Indeed. Yamaha, Technics and Sansui akso had very nice gear at the time, as did Kenwood (even if their "Age of Plastic" designs were a bit eccentric). Same for their music, actually. (Japanese instrument makers became as good as they were for a reason.)

That time i was 14-15 and crazy about hifi magazines. So much Marantz, Accuphase, Hitachi. Mitsubishi was not the typical player in this game (in germany). But very nice.

 

[jdg78]

Mitsubishi was noted for automotive in my book until now .
Thanks for widening my range of knowledge.

Pretty sure they also used to make TVs and VCRs back in the day. I remember my friend had a Mitsubishi VCR deck and I was always amazed at how much faster it would rewind the video cassette. This is back when you had to rewind the cassette before returning it to the rental store or else you’d get a penalty.

 

[MAB]

I dunno, the emerald green seems a bit overwhelming and is clashing with the deep red of the frequency display. This is not an easy one, and the stock choice of moderately bright warm white may be hard to beat, but what about, say, a nice amber?
View attachment 449682
('Shop for illustration purposes.)

I got the picture with the emerald green LED off the internet. I actually have a DA-F20, I kept the amber color.

BTW, this is another analog tuner with a grid-locked oscillator, like some Pioneers of the time. The high selectivity and low phase noise of a mechanically-tuned frontend (and I imagine nice weighted flywheel tuning at that) with the frequency stability of a PLL synthesizer.

Yes, the flywheel is very satisfying. It is a great tuner, for the few FM stations still interesting to me... I used to own the smaller matching amp and VU meters, but the amp was fragile so I sold the pair. The tuner and the preamp have been very reliable.

Indeed. Yamaha, Technics and Sansui akso had very nice gear at the time, as did Kenwood (even if their "Age of Plastic" designs were a bit eccentric). Same for their music, actually. (Japanese instrument makers became as good as they were for a reason.)

 

[AndreaT]

Yes! It brings back memories! There was an Italian magazine, Stereoplay, that tested electronics with measurements. The Mitsubishi amp and preamp tested well and I dreamt often (back then) about it, since their prices were totally outside my finances. It is now good to see that my dreams were not misplaced on the wrong rig!

 

[Yevhen]

Sweeping input voltage at unity gain results in the following output THD and THD+N:

I think it's bagging for the refresreshed electrolytic caps. This should reduce the 60Hz hum and it's harmonics

 

[AdrianusG]

Mitsubishi was noted for automotive in my book until now .
Thanks for widening my range of knowledge.

Yeah they made, and still make a lot of stuff, sadly no Audio equipment anymore AFAIK

 

[DSJR]

Not bad for 45 years old and it still looks the business.

You know, I now feel desperately sad that in the UK by the early 80s, I believe none of this ever found its way over here, as featureless Naim had taken over the lower high-end market with their carefully composed storyline, and boutique US brands such as Threshold (in the days before Krell and ARC here) and out there Electrocompaniet were making inroads to the more wealthy clients.

We had the Pioneer Spec pre and power amp to try and were against it right from the start (all about 'specs, not about music and look at all those knobs and switches!!!). I feel really terrible and full of guilt now, but it's all part of the learning curve and I admit I was very young then...

Mitsubishi made some nice tellies in Scotland I seem to recall. Cubic style as was the trend back then and the 20" we had, lasted well as a second TV until herself demanded a new slim flat panel type. I hated scrapping a still working TV but it joined the pile of CRT TVs being swapped for flat types around fifteen years ago... I forgot about their generally excellent range of VCRs as well...

 

[Mart68]

You know, I now feel desperately sad that in the UK by the early 80s, I believe none of this ever found its way over here, as featureless Naim had taken over the lower high-end market with their carefully composed storyline, and boutique US brands such as Threshold (in the days before Krell and ARC here) and out there Electrocompaniet were making inroads to the more wealthy clients.

We had the Pioneer Spec pre and power amp to try and were against it right from the start (all about 'specs, not about music and look at all those knobs and switches!!!). I feel really terrible and full of guilt now, but it's all part of the learning curve and I admit I was very young then...

Mitsubishi made some nice tellies in Scotland I seem to recall. Cubic style as was the trend back then and the 20" we had, lasted well as a second TV until herself demanded a new slim flat panel type. I hated scrapping a still working TV but it joined the pile of CRT TVs being swapped for flat types around fifteen years ago...

In '86 I almost bought the Mitsubishi X10 with the vertical turntable, it was heavily discounted.

Mitsubishi X10 Vertical Music Centre - Open Ear Audio - Melbourne's premium speaker, turntable and audio equipment design and repair workshop.

openearaudio.com

In the end went for a more conventional Aiwa unit. Regret that as the Mitsubishi was considerably superior in every respect, but I was 17 and knew nothing. That's the only time I can ever recall seeing any Mitsubishi audio product on sale in the UK.

Happily I did not have the money for Naim or even Rega so all my early equipment was Japanese; although, like you, I assumed the expensive UK stuff had to be 'better'.

 

[EJ3]

Funny, cassette decks were okay for cars and Walkmen, but they really were a pretty flawed delivery system for home audio. I was suprised that even the Nakamichi Dragon did not perform very well as tested here. That was the pinnacle of cassette technology.

That Nakamichi Dragon was no where near up to par.
Except for in the looks department.

 

[EJ3]

You know, I now feel desperately sad that in the UK by the early 80s, I believe none of this ever found its way over here, as featureless Naim had taken over the lower high-end market with their carefully composed storyline, and boutique US brands such as Threshold (in the days before Krell and ARC here) and out there Electrocompaniet were making inroads to the more wealthy clients.

We had the Pioneer Spec pre and power amp to try and were against it right from the start (all about 'specs, not about music and look at all those knobs and switches!!!). I feel really terrible and full of guilt now, but it's all part of the learning curve and I admit I was very young then...

Mitsubishi made some nice tellies in Scotland I seem to recall. Cubic style as was the trend back then and the 20" we had, lasted well as a second TV until herself demanded a new slim flat panel type. I hated scrapping a still working TV but it joined the pile of CRT TVs being swapped for flat types around fifteen years ago... I forgot about their generally excellent range of VCRs as well...

Funny, the only place that I have ever seen Threshold was at a place called British/American Sound. I lusted after it for many years (the display one had a clear top so you could see the electronics). Never got one, though.

 

[AnalogSteph]

I think it's bagging for the refresreshed electrolytic caps. This should reduce the 60Hz hum and it's harmonics

I dunno... the dominant harmonics seem to be H3, H5 and the fundamental, with the even orders you'd expect from a bridge rectifier (i.e. 120 Hz harmonics) trailing behind. The fundamental may be down to leakage current, but H3 and H5? And yes, I checked, only bridge rectifiers in this one. If the measurement setup passes the null / sniff test (H3 and H5 famously being those not cancelled out by a balanced input), it may be time to look at the mains wiring inside the device and which high-impedance nodes might benefit from some extra shielding.

BTW, the heck is this MC prepre?

Surely this would not be an inverting amplifier with a 10 ohm input impedance? Well, I'll be... it's right there in the specs, 10 ohms. I guess with MC carts being mostly resistive, you can pull it off, but wouldn't that be a bit less than ideal from a noise perspective?

I see someone discovered the "power transistors for low rbb'" trick a long time ago... but of course there's no rbb' data for either 2SD467 or 2SB561 out there, so without having some on hand nobody knows how suited they really are.

 

[DSJR]

Funny, the only place that I have ever seen Threshold was at a place called British/American Sound. I lusted after it for many years (the display one had a clear top so you could see the electronics). Never got one, though.

I believe the Threshold circuit morphed into the rather nice (and surprisingly cheap at the time compared to Krell, CJ, ARC and so on) Nakamichi PA 5 and 7 amps, which in series 1 form, had a couple of 'backward wired' caps I gather, due to a mis-read of the circuit. I understand the mklI versions corrected this and as mk1's would be drifted well off an dover heating etc. (because of this?) as a US pal's PA7 was when he bought it used, the correction is done as part of a very expensive service (he was happy to pay over $1500 to have it sorted, updated and broght back to full working order). It's a lovely powerful thing when working right and I had a PA5mk2 for a while until the dreaded valves tempted me to the dark side, (disastrously as it happened - never again ). These now >35 year old Nak amps and preamps seem to fetch at least as much as their new price today (PA7 was £2250 or so in 1989 or thereabouts and a Krell KSA80 was four grand or more)..

 

[Tovarich007]

Not bad for 45 years old and it still looks the business.

The seventies and eighties were japanese hifi Golden Age. Their companies knew how to design and build good, beautiful and reliable components.
I'm not surprised this preamp can still compete yet with good contemporary items.
Too bad for the power amp. My guess it should be good too.

 

[oldsysop]

Those were good amps, not today's Class D junk.

 

[tomtoo]

Those were good amps, not today's Class D junk.

.
15xmore expensive, 15xbigger, 15xmore heavy. But ok also 15xbetter looking

 

[formdissolve]

The font on the spec sheet gives me such nostalgia. Seems like almost every major Japanese brand used that font on their spec sheets and manuals!

 

[Eyexlr8]

This was my first preamp and amp . Soon after moved to Audire components but those never looked as good as these did

 

[DSJR]

The font on the spec sheet gives me such nostalgia. Seems like almost every major Japanese brand used that font on their spec sheets and manuals!

...And one of the main demo tracks played when I started in all this in 1974, was the track 'Halleluwah!' from master-copy of the album in your avatar picture I still love the album to this day...

 

[SegaCD]

1) No way I would blanket recap the unit as he did. The practice of blanket replacement of components actually introduces unreliability for either zero or (at best) random improvement.

I highly disagree with this statement. I repair electronics as a serious hobby and for others not for profit (except for maybe selling on eBay to get more tools and/or equipment to fix for myself and others). I am also an engineer that works for a major electronics company.
I see a lot of people state this idea of "capacitors good unless bad" but this a broad generalization. For audio equipment, that statement is more tolerable, but I work on computer equipment, video hardware, and other equipment which has high-frequency clocks, RF, etc or complex filtering. Capacitors don't always fail catastrophically. Their characteristics can change in a whole slew of ways that your capacitance and ESR meters won't tell you. As the electrolytic dries out, capacitors can get more sensitive to internal temperature or can have out-of-spec variance in ESR over a much larger range of frequencies (most ESR meters will only check at one low frequency like 1kHz). Capacitors at the end of life may also read in spec at lower voltages but short as voltage/charge increases (ESR meters again mostly test at a safe low voltage). This can also be a big problem in circuits with AC (e.g. amplifiers). You have all these non-linear and/or difficult to measure effects which can cascade into big problems with tolerance stack-up.
Capacitors are the only passives to have implied expiration dates on their white papers (with defined shelf life and hours of working life at a given temperature) and they should be considered consumables. (Yes, there are self-healing capabilities, but wet electrolytic capacitors may have some very mild chemical reactions after time either with the air or with the internals of the capacitors, especially with low-ESR caps which tend to have corrosive/water-based electrolytes. This damage is irreversible.)

I consider any device over 30 years old in need of a electrolytic capacitor replacement. They should have a shotgun replacement at the very least in the power supply with targeted replacement of capacitors where ripple and filtering is important and in locations where the devices in-line would be sensitive to complete failure of the capacitor. I personally try to recap devices top-to-bottom of that age if I intend to use it regularly or need it to be reliable. Otherwise, your hardware will suffer from various issues and require regular maintenance for potentially difficult-to-diagnose faults.

Why would unreliability be introduced into the hardware if you're using known-good, fresh components? Unreliability is always introduced as components age, and capacitors and other battery-likes objectively age first.

 

[MAB]

I highly disagree with this statement. I repair electronics as a serious hobby and for others not for profit (except for maybe selling on eBay to get more tools and/or equipment to fix for myself and others). I am also an engineer that works for a major electronics company.
I see a lot of people state this idea of "capacitors good unless bad" but this a broad generalization. For audio equipment, that statement is more tolerable, but I work on computer equipment, video hardware, and other equipment which has high-frequency clocks, RF, etc or complex filtering. Capacitors don't always fail catastrophically. Their characteristics can change in a whole slew of ways that your capacitance and ESR meters won't tell you. As the electrolytic dries out, capacitors can get more sensitive to internal temperature or can have out-of-spec variance in ESR over a much larger range of frequencies (most ESR meters will only check at one low frequency like 1kHz). Capacitors at the end of life may also read in spec at lower voltages but short as voltage/charge increases (ESR meters again mostly test at a safe low voltage). This can also be a big problem in circuits with AC (e.g. amplifiers). You have all these non-linear and/or difficult to measure effects which can cascade into big problems with tolerance stack-up.
Capacitors are the only passives to have implied expiration dates on their white papers (with defined shelf life and hours of working life at a given temperature) and they should be considered consumables. (Yes, there are self-healing capabilities, but wet electrolytic capacitors may have some very mild chemical reactions after time either with the air or with the internals of the capacitors, especially with low-ESR caps which tend to have corrosive/water-based electrolytes. This damage is irreversible.)

I consider any device over 30 years old in need of a electrolytic capacitor replacement. They should have a shotgun replacement at the very least in the power supply with targeted replacement of capacitors where ripple and filtering is important and in locations where the devices in-line would be sensitive to complete failure of the capacitor. I personally try to recap devices top-to-bottom of that age if I intend to use it regularly or need it to be reliable. Otherwise, your hardware will suffer from various issues and require regular maintenance for potentially difficult-to-diagnose faults.

Why would unreliability be introduced into the hardware if you're using known-good, fresh components? Unreliability is always introduced as components age, and capacitors and other battery-likes objectively age first.

Blanket recap is a bad practice because of the bathtub curve.
Early Life Fails in electrolytic capacitors is quite high, much higher than end of life fails.
If it was lower, and the rework is done flawlessly, then replacement makes sense if you have the time and money.