Realistic 42-2101A Review (Vintage Phono Stage)

[abdo123]

Probably input capacitor / resistor ?
Just curious though.
regards

resistors are probably fine, but all the electrolytic capacitors are way off their values, no doubt.

and the capacitors determine how accurate the filters are.

 

[SKBubba]

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.

This. In my younger days, no new hi-fi setup was done until a trip to Radio Shack for a cable, adapter, power strip, or something. My wife joked about it. In my early career of mainframe bank software development, no on-site implementation was finished without a trip to Radio Shack for an RS-232 cable, null modem adapter, breakout box, or something. Later on it was that one more ethernet or printer cable you needed. You could always find a Radio Shack, even in rural Alabama, Mississippi or South Georgia. Good times. Now, you might get lucky for something basic at the local Walmart which are ubiquitous. Anyway, thanks for the memories.

 

[LTig]

Can we safely say that 40 year old preamp didn't required replacng capacitors ? OR replacing them would have changed any measurements ?
Thanks for the review.
Regards.

I don't think so. The measurements show that it's fully on spec. Even the power supply noise shows higher mains noise (60 and 180 Hz components) than ps ripple (120 and 240 Hz components) so the big cap in the ps seems to be fine. The input elcap sees too low AC voltage, the output elcap lies within the feedback loop. The RIAA circuit has no elcaps.

 

[LTig]

To me this is thousand times more informative and interesting test than the thousanth dac or 2-way speaker test!

But where is the RIAA correction? https://en.wikipedia.org/wiki/RIAA_equalization

C12, C14, R18 and R20 for one channel (numbers -1 for the other).

 

[mhardy6647]

It happens

source: https://icouldbeahero.blogspot.com/2018/05/24.html
(my son's photoblog)

DSC_7455 (2) by Mark Hardy, on Flickr

On topic
@amirm THANK YOU for testing one of the "Little Rat" phono preamps! As you may know, these things have developed a latter day cult-like following, and there are folks selling tarted-up versions for crazy money on (e.g.) eBAY. I have been perversely interested in minimalist MM phonp preamps for... a while... there are (presumably) much better transistors available today than the presumably very cheap ones spec'd in these cheap little preamps (e.g.). Then again, I do tend to be a less is more kinda guy, when it comes to hifi reproduction hardware (at least).

Looks like they had a good intention there with the rumble filter, cutting out the low frequencies. Alas, that is causing that peaking so may make the sound bass heavy.

Given the amplifier and loudspeaker hardware of the time, and to which these preamps would be attached -- the bump is probably a feature (whether intentional or not).

 

[MerlinGS]

Given the amplifier and loudspeaker hardware of the time, and to which these preamps would be attached -- the bump is probably a feature (whether intentional or not).

That's exactly what crossed my mind when I saw that. A couple of decades back I purchased a couple of Chase RLC 1 preamps really cheap (I think ~$20 each, sale was mentioned in the old basslist, they were new and included a remote). The preamp had a pretty nice bump around 30Hz-40Hz, which I'm sure was purposely added. I added a couple of capacitors to one of the units and its frequency response seemed to be flat after that. Depending on purpose I could choose with which preamp to play.

PS I have noticed a couple of people mention the RLC 1 was passive, but my experience suggests otherwise.

 

[SmackDaddies]

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.

We became the disposable society. Back in the 70's you still had electronic repair shops in virtually every community also, even small ones.

 

[AlexF]

When the average citizen cannot afford items that are made in their own country, it is telling. Or when items cannot be made in their own country because the very cost of manufacture prices them out of reach of the average citizen.

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.

 

[murraycamp]

no new hi-fi setup was done until a trip to Radio Shack

Preach. I miss the Shack. I always have weird electronic projects (telescope drivers, aquarium lighting controllers, etc.) and I would get stuck, go up there and those guys would help me out - usually with less than $10 in parts. Now, I have to ask you bozos for help. RIP RS.

 

[mrmoizy]

The unit was made in August 1981, so it's nearly 40 years old. The 2101A came in late 1979 and ran for many years, although IIRC, the later ones came out of Taiwan.

Here's the specs:
View attachment 107707
And the schematic:
View attachment 107708

The overload spec seems to be spot on at 1%/100mV.

That hand-drawn circuit layout! Epic.

 

[Blumlein 88]

I am of an age where I remember Japan as a super cheap supplier of tatty copies, a bit like the image China is ascending from now.
In the UK when I was an apprentice "japped" was slang for making a bodged copy.
How things have changed, the epitome of quality engineering most can't afford now!

My Dad needed an outdoor faucet to replace a leaky old one when I was about 10 years old. He had me ride my bike the few miles to the hardware store and get one. 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.

 

[AudioTodd]

This. In my younger days, no new hi-fi setup was done until a trip to Radio Shack for a cable, adapter, power strip, or something. My wife joked about it. In my early career of mainframe bank software development, no on-site implementation was finished without a trip to Radio Shack for an RS-232 cable, null modem adapter, breakout box, or something. Later on it was that one more ethernet or printer cable you needed. You could always find a Radio Shack, even in rural Alabama, Mississippi or South Georgia. Good times. Now, you might get lucky for something basic at the local Walmart which are ubiquitous. Anyway, thanks for the memories.

Mind saying who you worked for? We were, in a different life, early customers of jack henry and associates, inc. (I think all of the name was lowercase back some few decades or so ago if I remember correctly. My Nephew actually works for them now).

 

[StefaanE]

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.

And all over the world. And they were PC pioneers. I bought a TRS-80 (affectionately known as Trash-80) Model 2 with 16K RAM, monitor, cassette deck and cassette-based assembler back in early 1979, from a Radio Shack store in a suburb of Antwerp, Belgium. It cost me about two months worth of wages, but was much more of a "real" computer than the COSMAC ELF with its 256 bytes of RAM, and super-sophisticated toggle-switch program entry I'd assembled myself.

 

[LTig]

My Dad needed an outdoor faucet to replace a leaky old one when I was about 10 years old. He had me ride my bike the few miles to the hardware store and get one. 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.

But I bet the Honda was the better choice regarding reliability, fuel consumption and price.

 

[SKBubba]

Mind saying who you worked for? We were, in a different life, early customers of jack henry and associates, inc. (I think all of the name was lowercase back some few decades or so ago if I remember correctly. My Nephew actually works for them now).

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

 

[Hiten]

I don't think so. The measurements show that it's fully on spec. Even the power supply noise shows higher mains noise (60 and 180 Hz components) than ps ripple (120 and 240 Hz components) so the big cap in the ps seems to be fine. The input elcap sees too low AC voltage, the output elcap lies within the feedback loop. The RIAA circuit has no elcaps.

The C14 may be electrolytic cap. But I am not sure though. Shown here in the center
LINK
- - - - - - - - - - - - - -
I had a japanese Phono preamp. Bought just for fun. It sounded good. The schematic came with single page literature. Please see below pic.

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.

 

[milosz]

This is probably all anyone needs for vinyl. Vinyl has such a poor S/N ratio, output of a cartridge tracing a groove has loads of THD in general.

The heroic $20,000 multi-chassis phono stages are really great, though. Great at separating people from their cash.

( Keep in mind that I am being facetious before you comment in anger. Nearly pure snark, yes- but with more truth than the vinylphiles I know would ever admit. )

 

[watchnerd]

As you may know, these things have developed a latter day cult-like following, and there are folks selling tarted-up versions for crazy money on (e.g.) eBAY.

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?

 

[SIY]

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

Having the volume control at the output is a serious error. The output impedance will vary with frequency, and at the halfway volume point, the output impedance will be 12k or so, way too high.

 

[Hiten]

hi,
the module didn't came with any volume control. It was simple assembled board with no casing. It had turret type terminals to connect PS, Input and output. Dont know how these were meant to be connected to any system. I tested it with aux in of an amplifier. Which I guess would have been having volume control at same point.
Any solutions ?
thx & regds.