Realistic Stereo 24

[chadwick404]

Hi - does anybody have any literature or info/opinions on this amp? I just bought one from ebay, it is my first foray into tubes, and although I know it is low power, I have often found, especially for vintage, that Realistic units are often way under rated. I am hoping this is the case here. I seek "great sound" (duh) at a lower investment than some of the stuff I've seen float around (yikes). I have a variety of quality and efficient, new or vintage speakers to use with the amp, and intend to have the unit thoroughly inspected/bring-to-spec by a local respected stereo guy.

But I'd like anyone else's thoughts...worth putting some bucks into? Good circuit design? Waste of time? A manual would be most welcome...!! Thanks folks...

Chad

Yamaha Cr-1020 and CR-2040
Realistic Nova 8Bs
Athena model somethings - very nice
Boston Acoustics Micro 90s and 90c - excellent for the money, they pair well with athenas and i've heard few speaker matchings that did as well
Integra 8.3 Receiver - solid performer, clean sound
Onkyo Integra TH-SV919 THX - sweet sound - heavy as hell
Bunch of other misc...but I do say my stuff holds its own with any similar power range...

 

[Eli Duttman]

Google doesn't turn up a schematic. However, it seems the unit employs the 6BQ5/EL84. Look inside and jot down the tube complement. Unless the O/P trafos are complete garbage (unlikely) the unit should be worth refurbishing. If you're very lucky, NICE Hashimotos are present and not refurbing is criminal.

Contact R/S to see if they can provide a schematic.

 

[kevinkr]

I had a Realistic Stereo 24A which sounded very good actually, and used 6BM8s in the output stages and a couple of 12AX7A in the phono section. No idea what happened to it. Lost sometime over the last 10yrs..

Based on more recent experience with a Realistic Stereodyne 40, JJ electrolytic caps might just slot neatly into the amp as replacement caps for the power supplies.

The coupling caps in these amps are good sounding, but incredibly leaky paper things that must be replaced if the amp is to be reliable.

Don't know who made the OPTs in these amps, but they are tiny - and perform way, way better than they should. Rumors abound that the cores are actually something special like permalloy. Can't really confirm, but the lams are very thin and there are a great many of them.

There are sams for all of these amplifiers.

 

[chadwick404]

Thanks

Thanks for the replies, guys. I appreciate it. What's a "sam"?

I will post more info once I get it and have a chance to inspect - should come home early next week.

I'll hope for the better transformers - the pictures, too me, seemed like some heavy iron, but I really have no good idea. My older Yamahas and an Onkyo have some serious iron in them, but of course they are geared for different duties.

More comments are welcome, especially from any current owners.

Cheers.

 

[chadwick404]

Thanks for all the replies - what is a "sams"?

 

[chadwick404]

Never mind - I figured it out. However, they (Sams) did not have a "Realistic Stereo 24" amplifier - I'll have to wait until it gets here to evaluate.

Cheers.

 

[mashaffer]

I await with interest. I have always been a fan of vintage 1970s Realistic sand but have no knowledge of their hollow state efforts.

 

[Eli Duttman]

Kevin's remarks lead me to believe that the R/S unit might be related to the Sansui 500. That receiver uses 6BM8 "finals" too and the paper in oil (PIO) coupling caps. employed are notorious for leaking. Those caps. should be replaced by Soviet surplus K40s.

When the unit arrives, definitely take a look and jot the tube complement down. Under no circumstances should the unit be plugged in. A variac is needed to slowly ramp the voltage applied up. The filter caps. need reforming, at a minimum, and rate to require replacement.

 

[chadwick404]

Thanks Eli, that is quite interesting. As I stated, I happen to think many items of Realistic vintage are a bit underrated...my local stereo tech is actually well versed on stereo matters. I will run your thoughts past him.

I actually considered Sansui 111 (I think that is the model)...I have high regard for much of Sansui older equipment - but the prices were more than I wished to devote. So I am hopeful the R/S piece is a "copy" or very good original design of contemporary items.

Anybody ever check out Radio Shack Catalogs ? The older catalogs show Realistic selling Mcintosh, Bogen, Lafayette, Scott and Stromberg-Carlson, among several others - surely they had to compete with those brands at some level, too.

Best regards and thanks for the input.

 

[chadwick404]

Well, I can't tell what transformers it has; nor much about the design. Of course, I am an industrial engineer, not electrical. It has a bias control on the back, I think - it is labeled "hum balance"...?

Still, it looks solid and quality, overall...thoughts? I am taking it to my tech guy for a good overhaul...the receiver below it is a 40/T I will revamp eventually.

 

[chadwick404]

I forgot to write down the tubes - seemed to be three types, total: 4 of one type, 2 of another, one final type. 7 total, I think. I'll get the numbers later this week. Cheers.

 

[chadwick404]

Eli, how do I tell if what type of transformers are in it?

 

[Eli Duttman]

Eli, how do I tell if what type of transformers are in it?

Post a photo of all 3 trafos and get some feedback from this site's "iron" experts (not me). I'm guessing the leftmost trafo in the image already posted is the power trafo, but let's be sure.

 

[chadwick404]

OK: 4 x 6BM8, 2 x 12AX7, 1 x 6CA4. How do I determine the maker of the transformers?

 

[Eli Duttman]

The 6CA4 is the B+ rectifier. The 6BM8 is a small signal triode and a power pentode in a single envelope. The likely 6BM8 topology is common cathode voltage amplifier DC coupled to a "concertina" phase splitter and on to PP "finals". Finally, the 12AX7 triodes are used in the phono section (1 tube/channel).

Do you see anything that looks like SS rectification, which would be used in a DC heater supply for the phono section. In a bottom of the line unit, like this model, expect AC heating in the phono section, which is undesirable, but can be made to function tolerably well. Buy a pair of phono grade Sovtek 12AX7LPS tubes from Jim McShane, as part of the restoration. The 'LPS has a spiral wound, hum bucking heater, that can easily be the difference between a listenable phono section and an unbearable state of affairs.

 

[chadwick404]

"Bottom of the line unit" - oh my - you are not inspiring much hope here. Is it worth more money (after my lovely ebay purchase price)?

I've since read up a bit on the 6BM8 tubes, and support tubes; it seems they are well regarded in many older Japanese topologies. But maybe not in this particular amp...? I am much more interested in a high quality sound than any sort of real power. I have some excellent solid state stuff that can rock all I desire, old and new.

I toyed with buying an old Sansui tube amp - maybe I should?

Although I have an old Garrad I may hook up, my main playing would probably be from an MP3 player. Will this be a problem?

 

[kevinkr]

"Bottom of the line unit" - oh my - you are not inspiring much hope here. Is it worth more money (after my lovely ebay purchase price)?

<snip>

Although I have an old Garrad I may hook up, my main playing would probably be from an MP3 player. Will this be a problem?

It's not the bottom of the line Radio Shack unit from that era, but about the middle of the range, and can sound great - in fact it is one of the best sounding stereo amps in the early Realistic line up. I had one in an office system and it was very pleased overall with its performance. It had a very warm liquid midrange, overall smooth vintage sound, and what could be described as slightly flabby bass probably due to the old electrolytics in the supply, and very nice extended highs. It imaged very well. Very synergistic with the Paradigm Atoms I paired it with. (I never heard them sound better frankly)

The transformers are proprietary to Technical Apparatus, Inc., not sure who the OEM for those transformers were - it could have been Hashimoto, or anyone else for that matter. (You'll not find out by looking at them, and do not disassemble unless necessary as they can be fragile from age.) They are of sufficiently good quality to justify doing a restoration on this amplifier. The phono stage is relatively mediocre by today's standards, but will suffice for casual use.

 

[kevinkr]

Post a photo of all 3 trafos and get some feedback from this site's "iron" experts (not me). I'm guessing the leftmost trafo in the image already posted is the power trafo, but let's be sure.

It is.. As noted there is little or no reliable information on these transformers, but they are just fine performers as I noted in my previous post. This amp is worth R-e-S-t-O-r-I-n-G..
There is a SAM Photofacts for this amplifier IIRC.

 

[chadwick404]

Thanks Kevin - I do intend to restore. Do you happen to have a manual or other shareable documents on the unit?

 

[kevinkr]

Thanks Kevin - I do intend to restore. Do you happen to have a manual or other shareable documents on the unit?

Good to hear, unfortunately I no longer have any of the documentation as it was lost along with the unit in question.

You may be able to find scans of the Sams on eBay for very little money.