Realistic 42-2101A Review (Vintage Phono Stage)

[LTig]

The C14 may be electrolytic cap. But I am not sure though. Shown here in the center
LINK

C14 in the pic looks certainly like an elcap, but C14 in the schematics is 0.0047uF (=4.7 nF) and is definitely no elcap.

I had a japanese Phono preamp. Bought just for fun. It sounded good. The schematic came with single page literature. Please see below pic.
View attachment 107856
Can you tell
1) In power supply Is 220 ohms resistor in series bleeder resistor ? Shouldn't it be parallel to cap and different value ?
2) does RIAA schematic look like if it is okayishly well made ? or any mods you can suggest ?
3) Parallel resistor+caps at bottom in center of schematic are for equalization ?
Thanks and regards.

Answers to your questions:

1. It's not a bleeder resistor, it creates a 1st order low pass filter (f3 = 1.5 Hz) together the 470uF elcap, to reduce power supply ripple.
2. It looks like a typical RIAA circuit, but the values of the resistors hint to being from E12 series so probably (a) not 1% precise and (b) not close enough to the theoretically required values. Standard in quality preamps are 1% precision resistors from E96 series, and even then one would use two E96 resistors either in series or in parallel to come closer to theoretically calculated values.
   I might try to calculate the frequency response but only for the case of infinite open loop gain. The AN360 datasheet however reveals that it's not an operational amplifier, far from it, so the assumption of sufficient open loop gain at higher frequencies may be wrong, resulting in deviation from real response.
3. yes.

 

[Frank Dernie]

When I returned he saw it was made in Japan. He had me ride back and get a refund and complain to the owner (whom he knew) about selling Jap junk. He wasn't going to risk installing a junk faucet that could leak again and cost him more money. He was not amused when years later I purchased a Honda Accord.

This is common amongst WW2 veterans from the Pacific front.
My "uncle", a close family friend I called "uncle", had worked on the Burmah railway as a POW. I won't repeat his opinions in this day and age but his son bought a little Sony radio with the proceeds of his paper round. When his Dad saw it he took it into the garage, put it on his workbench, and smashed it into small pieces with a hammer.
He then refunded him and explained that would be the fate of anything Japanese brought into his house.
It had nothing to do with quality for him.
Time is a great healer, thankfully.

 

[Frank Dernie]

Nice to see a phono stage with an effective subsonic filter to remove the spurious rubbish.
That on its own makes it better than many on sale today.

 

[ThatM1key]

I bet the Realistic sa-150 would beat the realistic pre amp. sa-150 has a switchable cartridge section and even jacks for speaker. I'll be it, only 1 watt at 8 ohms. They both go around the same price on ebay. I would pick the one with more options.

 

[StefaanE]

Time is a great healer, thankfully.

My Dad (who lived in Antwerp during WW2, and vividly remembered the V1 and V2 bombings, got quite anxious at the idea of a united Germany back in 1991. He really believed they would revert to the ways of the third reich.

 

[Hiten]

It's not a bleeder resistor, it creates a 1st order low pass filter (f3 = 1.5 Hz) together the 470uF elcap, to reduce power supply ripple.

Thanks LTig.
Just for testing purpose I had replaced 470uf Capacitor with 1000uf capacitor. Because I didn't had 470uf with me. However this was only for testing purpose. What would be the outcome of 1000uf capacitor in place of 470uf ? A little higher low pass ?
Regards.

 

[SIY]

What would be the outcome of 1000uf capacitor in place of 470uf ? A little higher low pass ?
Regards.

Almost nothing. Power up very slightly slower since that doubles the time constant, which is a non-critical value. To put in a caveat, electrolytics tend to have wide tolerances, and usually skewed higher. So it isn't like this is crazy different than stock.

 

[anmpr1]

I call BS on this. Making and importing from somewhere else is just cheaper (and you’ve gotten used to that) but only because you don’t care about impact on that somewhere - human exploitation, environment exploitation, tax evasion, etc.

That is pretty much what I implied. There is nothing BS about it. In the context of audio, David Hafler once said that, at least temporarily, outsourcing is great for the consumer, but bad for the worker. And once the worker no longer has a job, what good is a cheap product to him if he cannot afford it?

 

[anmpr1]

And all over the world. And they were PC pioneers.

What killed that was Tandy's commitment to proprietary architecture/software. It's the same thing that killed IBM PS/2. The Microchannel bus. I had a Tandy 2000. Very nice machine in the context of the era, but it soon became incompatible with anything else. In a few years it was an expensive box taking up space in a closet.

RS stores were originally geared to the do it yourself hobbyist. It was a place where you could buy replacement electronic parts. But with throw-away electronic stuff no one needed that. You might go in for a battery, or a fuse. Maybe... until stuff began to be made without fuses. They got in to cell phones and radio controlled toy cars. By then it was over for the operation.

 

[LTig]

I might try to calculate the frequency response but only for the case of infinite open loop gain. The AN360 datasheet however reveals that it's not an operational amplifier, far from it, so the assumption of sufficient open loop gain at higher frequencies may be wrong, resulting in deviation from real response.

Done. Since this is not for the device tested in this thread but for the japanese phono preamp the remainder is behind the spoiler.

Spoiler: Simulated frequency response of japanese phono preamplifier

The plots shown below are created using gnuplot with the attached command script. Just run gnuplot from the command line:
gnuplot japanese_preamplifier.txt
Beware that the calculated frequency response is based on infinite loop gain which is not the case.

 

[LTig]

Thanks LTig.
Just for testing purpose I had replaced 470uf Capacitor with 1000uf capacitor. Because I didn't had 470uf with me. However this was only for testing purpose. What would be the outcome of 1000uf capacitor in place of 470uf ? A little higher low pass ?
Regards.

No, f3 will be halved (lower).

 

[StefaanE]

What killed that was Tandy's commitment to proprietary architecture/software. It's the same thing that killed IBM PS/2. The Microchannel bus.

For a while, they were one of the standard architectures. People made clones of the TRS-80 (remember the Lobo?), and provided alternatives to TRSDOS (remember LDOS?). The real problem was that the machine had no bus, and that the Z80 was a dead end. The Microchannel bus was expensive and wasn’t compatible with the PC bus, and by the time IBM launched it, they no longer had the clout to impose a new architecture. Plus the PC bus was good enough until it was replaced by consensus in an industry no longer dominated by IBM...

 

[mhardy6647]

Huh.

I guess I have to turn in my vinylista card for being completely unaware that there was a cult around these things...

Maybe it's time to send Amir some cult following SUTs?

Cinemag, anyone?

Pick a weird thing (any weird thing). Google. Find a cult.
Pro tip: you might wanna turn "Safe Search" on if you try this.

Back on(ish) topic:
https://audiokarma.org/forums/index.php?threads/check-out-this-cool-little-phono-pre.173388/
https://www.audioasylum.com/cgi/t.mpl?f=vinyl&m=131175
https://forums.nasioc.com/forums/showthread.php?t=649488 (it's a Subaru Impreza forum?!)

here's one you can spend $95 for (this is the battery-powered morph, which I suppose is felt to be superior )
https://www.ebay.com/itm/Realistic-...521800?hash=item4b7bdb6048:g:JvMAAOSwocFe6SOW
... or the full Monty for 200 smackers (US)
https://www.ebay.com/itm/Realistic-...675322?hash=item2cfff2fbfa:g:gvIAAOSws11eA9y8

 

[anmpr1]

For a while, they were one of the standard architectures.

I think it would be better to say that there wasn't any clear standard when it all began to take off, but soon a standard evolved. And that left both Tandy and IBM (their PC line) out of the running (IBM took longer to give up, simply because they were IBM). The scene changed rapidly. Back then if you wanted a PC you'd go to a stand alone PC store. Tandy had their business oriented stores. Compaq and some of the others I recall.

When things did become 'standardized' it was all off the shelf commoditization. You'd go to the newsstand and buy an copy of Computer Shopper--all ten thousand pages of it, each issue. Like the NYC phone book! Build or upgrade what you had. Or buy from Zeos (or one of the many other mail order assemblers), more or less made to order. Then you had to decide: Do I want Word Perfect, Ami Pro, or MS Word? Got to have Lotus 123, for sure! dBASE. And a screen saver with flying toasters.

How times have changed!

 

[mhardy6647]

I think it would be better to say that there wasn't any clear standard when it all began to take off, but soon a standard evolved. And that left both Tandy and IBM (their PC line) out of the running (IBM took longer to give up, simply because they were IBM). The scene changed rapidly. Back then if you wanted a PC you'd go to a stand alone PC store. Tandy had their business oriented stores. Compaq and some of the others I recall.

When things did become 'standardized' it was all off the shelf commoditization. You'd go to the newsstand and buy an copy of Computer Shopper--all ten thousand pages of it, each issue. Like the NYC phone book! Build or upgrade what you had. Or buy from Zeos (or one of the many other mail order assemblers), more or less made to order. Then you had to decide: Do I want Word Perfect, Ami Pro, or MS Word? Got to have Lotus 123, for sure! dBASE. And a screen saver with flying toasters.

How times have changed!

1) don't forget the S-100 bus

2) flying toasters are the best, man! Brave little toaster(s).

... but I digress.

 

[anmpr1]

2) flying toasters are the best, man! Brave little toaster(s). ... but I digress.

I'd forgotten about that. Imagine, if you will, the irony of a 'politically radical' musical group singing about 'the revolution' ("free minds, free bodies, free dope, free music...") taking a software company to court over copyright infringement! You can't make that stuff up.

 

[mhardy6647]

I'd forgotten about that. Imagine, if you will, the irony of a 'politically radical' musical group singing about 'the revolution' ("free minds, free bodies, free dope, free music...") taking a software company to court over copyright infringement! You can't make that stuff up.

View attachment 107969

Yeppers.

 

[pjug]

The best thing about Radio Shack was that they had stores even in smallest towns. So if you needed something, you could drive and get it. Even today that would be a good resource to have. Shame they closed up.

I think I've posted this before, but also great were the quirky folks staffing these stores. And these stores existing as a nice fit for employment of these people. Maybe Best Buy Geek Squad has taken over that role?

 

[Hiten]

Done. Since this is not for the device tested in this thread but for the japanese phono preamp the remainder is behind the spoiler.

Thanks a lot LTig. I am newbie But I presume response deviation to be +/-3dB. And in actual preamp; if tested it may be not that severe. But still not a quality preamp. Nice to know these things.
Regards.

 

[AudioTodd]

A competitor, Kirchman. Later started a company that had a product that interfaced with JHA, had a contract with them for years. Good company.

Quite familiar with them! Out of the blue, every bank officer of every "small" bank got a big orange binder of regulatory compliance materials in the mail from them and nobody knew who they were or why they were sent it!! I don't know how it worked out for them, but it sure got them on the map and people loved that binder while it was still current.

My Dad made a nice bundle on JKHY - their headquarters was about 45 minutes from the house I grew up in. He unfortunately sold my IPO stake for me at a loss - I often asked him if he was SURE it was MY 3,000 shares he sold and not HIS 3,000 shares that "he" still had...