A Pioneer SX-950 born in 1976:
(tl;dr at the ------- before the pictures)
It was my dad's, I got it from him when I weighed just a bit more than it did and I used it as my main amplifier for the better part of 20 years.
It was rated 85WPC into 8 ohms, 110W into 4, but, like a lot of vintage gear, was much more powerful than that. But doubly so, because this thing was not just regular grade awesome, it was next level --- it could shove 43 volts from 20Hz to 200Hz into a subwoofer I made with a 6 ohm dual voice coil driver. Since 6 ohms means 4-5 ohms, let's be conservative and say 4.8 ohms - 43 volts makes just shy of four-hundred watts per channel - 400W x2!!!!
And we can't forget the transients! Easily 250W into 8 ohms. SX-950 has two 63V 22,000uf caps with extremely low ESR. How do I know extremely? I never measured, but size was the giveaway! (about as wide as an 8oz pop can, and an inch and a half taller). All power amp related components had wires wrapped around the leads about 6-10 times, extremely tightly! I love seeing such craftsmanship. Oh, last thing: stable down to below 2 ohms (probably 1.3-1.4ish), though not listed anywhere.
OK, now that you know how awesome the beautiful machine pictured above is (I mean, how could you not want to know? Wouldn't it be nice if these were the kinds of amps you could buy today walking into a major retailer?! I certainly think so!
Onto the issue: SX-950 had a 16 gauge aluminum power cord (lol mid 70s...), which was terminated into a non-polarized plug.
The entire time I used it, I never had a ground loop problem that could be solved by reversing the polarity of the plug.
...Not that there were many issues - problems were extremely rare. One thing that did happen, though, when the receiver wasn't plugged in right (I never paid attention and this might've happened all the time, but, knowing what I know, I doubt it), if you ran the back of your finger along the bezel around the glass covered AM/FM dial, you could feel the 60Hz power in the form of 120Hz buzzing in your finger, more intensely in your forearm, and about half way up your arm to a little past your elbow. It was great! Like being electrocuted without the pain.
So, like I said, never any issues with playback. Also never had anything break or malfunction from what I assume must have been some pretty serious voltage differentials between components at times. (Thankfully its input impedance (and the impedance of other components) were all something between 10 and 20k)
I also have a Pioneer RT-707, an excellent reel-to-reel which uses 1/4 inch tape at 3.75 or 7.5 IPS.
Oh, I forget the model number, but I also had their best (of two) equalizers from 1980 - the last silver-faced brushed aluminum model before all the manufacturers switched to the cheap black plastic crap that defined the 80s. Don't get me wrong, some stuff looked good, and some even still does. But you can't argue it wasn't a downgrade...
Anyway, both units had inputs and outputs (hooked up to "play" and "record" on the receiver) which I hooked up to Tape 1 and Tape 2.
Neither of these devices' power cables are polarized either. And the entire time, none had issues (with themselves or with other gear hooked up over the years, including computers and TVs). Unfortunately, pretty recently, my RT-707 finally begun exhibiting symptoms you'd expect it to have begun exhibiting a couple decades ago, not at nearly 48 years old. It's not horrible and I have a workaround to fix it, but a couple of its caps need replacing. Since the electrolytics are basically 50 years old now (they could be if they were ordered in '74, which is easily possible...), and the unit has been off for almost a year, it's probably best to do them all. Only a couple really really really need doing for performance issues, it's just going to be sooo much work when I have to...
So... all this stuff worked together and with other stuff that didn't have polarized plugs (and did..), including sensitive stuff, and only a couple times ever did I run into issues that needed fixing. And they could always be fixed (just never by reversing polarity of the power plug, like I said).
-------
In more recent news (and also related) I got myself a Topping LA90 Discrete - another class AB amplifier that's similar in some ways, but quite different in others. One of the biggest differences is probably the power supply, SX-950 being internal linear: unregulated, LA90 Discrete being external switch mode: regulated.
LA90 Discrete's external PSU also came with a non-polarized plug on its detachable wire. Before I remembered what I wrote above, I got pretty concerned about it, but now I'm not as concerned.
Not that I'm not conerned - I'm still a little concerned...
Does anyone know what potential issues could arise if the side of the SMPS that [I assume] was likely designed to be neutral, gets live (and v.v.)?
Reason being, I need to be careful with my LA90 Discrete - China is far away and I have a feeling that in the not-too-distant future, bad things are going to happen there, and when they do, the warranty I have could be pretty useless. Obviously yes I do care about the people living there, but music is my favourite and I care about it too. I'm not too concerned about it breaking my other stuff I connect to it, though it'd suck if one of my matched woofers got blown and I needed to replace both of them. Or tweeters. Or DAC or interface or etc.
Here's some pictures I took of my LA90 Discrete:
This is the part that goes into the wall. Both pegs are the same width
This hideous thing is on the SMPS itself - it's the female end of the other end of the power cable (the wall end of which is pictured above).
This is the top part of the SMPS sticker - the only informative part. As you can see, it's not too informative.
Technically these aren't of the LA90 Discrete, but its power supply / cord.
Thoughts on non-polarized amps?
-Regulated make a difference?
-SMPS make a difference?
(tl;dr at the ------- before the pictures)
It was my dad's, I got it from him when I weighed just a bit more than it did and I used it as my main amplifier for the better part of 20 years.
It was rated 85WPC into 8 ohms, 110W into 4, but, like a lot of vintage gear, was much more powerful than that. But doubly so, because this thing was not just regular grade awesome, it was next level --- it could shove 43 volts from 20Hz to 200Hz into a subwoofer I made with a 6 ohm dual voice coil driver. Since 6 ohms means 4-5 ohms, let's be conservative and say 4.8 ohms - 43 volts makes just shy of four-hundred watts per channel - 400W x2!!!!
And we can't forget the transients! Easily 250W into 8 ohms. SX-950 has two 63V 22,000uf caps with extremely low ESR. How do I know extremely? I never measured, but size was the giveaway! (about as wide as an 8oz pop can, and an inch and a half taller). All power amp related components had wires wrapped around the leads about 6-10 times, extremely tightly! I love seeing such craftsmanship. Oh, last thing: stable down to below 2 ohms (probably 1.3-1.4ish), though not listed anywhere.
OK, now that you know how awesome the beautiful machine pictured above is (I mean, how could you not want to know? Wouldn't it be nice if these were the kinds of amps you could buy today walking into a major retailer?! I certainly think so!
Onto the issue: SX-950 had a 16 gauge aluminum power cord (lol mid 70s...), which was terminated into a non-polarized plug.
The entire time I used it, I never had a ground loop problem that could be solved by reversing the polarity of the plug.
...Not that there were many issues - problems were extremely rare. One thing that did happen, though, when the receiver wasn't plugged in right (I never paid attention and this might've happened all the time, but, knowing what I know, I doubt it), if you ran the back of your finger along the bezel around the glass covered AM/FM dial, you could feel the 60Hz power in the form of 120Hz buzzing in your finger, more intensely in your forearm, and about half way up your arm to a little past your elbow. It was great! Like being electrocuted without the pain.
So, like I said, never any issues with playback. Also never had anything break or malfunction from what I assume must have been some pretty serious voltage differentials between components at times. (Thankfully its input impedance (and the impedance of other components) were all something between 10 and 20k)
I also have a Pioneer RT-707, an excellent reel-to-reel which uses 1/4 inch tape at 3.75 or 7.5 IPS.
Oh, I forget the model number, but I also had their best (of two) equalizers from 1980 - the last silver-faced brushed aluminum model before all the manufacturers switched to the cheap black plastic crap that defined the 80s. Don't get me wrong, some stuff looked good, and some even still does. But you can't argue it wasn't a downgrade...
Anyway, both units had inputs and outputs (hooked up to "play" and "record" on the receiver) which I hooked up to Tape 1 and Tape 2.
Neither of these devices' power cables are polarized either. And the entire time, none had issues (with themselves or with other gear hooked up over the years, including computers and TVs). Unfortunately, pretty recently, my RT-707 finally begun exhibiting symptoms you'd expect it to have begun exhibiting a couple decades ago, not at nearly 48 years old. It's not horrible and I have a workaround to fix it, but a couple of its caps need replacing. Since the electrolytics are basically 50 years old now (they could be if they were ordered in '74, which is easily possible...), and the unit has been off for almost a year, it's probably best to do them all. Only a couple really really really need doing for performance issues, it's just going to be sooo much work when I have to...
So... all this stuff worked together and with other stuff that didn't have polarized plugs (and did..), including sensitive stuff, and only a couple times ever did I run into issues that needed fixing. And they could always be fixed (just never by reversing polarity of the power plug, like I said).
-------
In more recent news (and also related) I got myself a Topping LA90 Discrete - another class AB amplifier that's similar in some ways, but quite different in others. One of the biggest differences is probably the power supply, SX-950 being internal linear: unregulated, LA90 Discrete being external switch mode: regulated.
LA90 Discrete's external PSU also came with a non-polarized plug on its detachable wire. Before I remembered what I wrote above, I got pretty concerned about it, but now I'm not as concerned.
Not that I'm not conerned - I'm still a little concerned...
Does anyone know what potential issues could arise if the side of the SMPS that [I assume] was likely designed to be neutral, gets live (and v.v.)?
Reason being, I need to be careful with my LA90 Discrete - China is far away and I have a feeling that in the not-too-distant future, bad things are going to happen there, and when they do, the warranty I have could be pretty useless. Obviously yes I do care about the people living there, but music is my favourite and I care about it too. I'm not too concerned about it breaking my other stuff I connect to it, though it'd suck if one of my matched woofers got blown and I needed to replace both of them. Or tweeters. Or DAC or interface or etc.
Here's some pictures I took of my LA90 Discrete:
This is the part that goes into the wall. Both pegs are the same width
This hideous thing is on the SMPS itself - it's the female end of the other end of the power cable (the wall end of which is pictured above).
This is the top part of the SMPS sticker - the only informative part. As you can see, it's not too informative.
Technically these aren't of the LA90 Discrete, but its power supply / cord.
Thoughts on non-polarized amps?
-Regulated make a difference?
-SMPS make a difference?
