Rohde & Schwarz HS86 mains AC voltage stabilizer

ID: 287559
Rohde & Schwarz HS86 mains AC voltage stabilizer 
12.May.12 10:32
27

Allan So (HK)
Articles: 15
Count of Thanks: 12

Dear Seniors, Editors and fellow Radiophiles,

I am posting pictures of this rare Rohde & Schwarz HS86 mains AC voltage stabilizer, please feel free to use in RadioMuseum liberally.

The only specifications I know: input 190-230VAC, output 220VAC +/-0.2%, 500VA max, tubes--one EL34, one diode D1,8/1,2

Soundwise: very stable rock-solid soundstage, extremely dark background, without slightest dynamic compression.

The steel cage must be removed during operation, otherwise it vibrates (induced by the transformers) with a loud audible hum.

Prost!

Allan

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 2
Create Model 
12.May.12 11:54
27 from 5789

Michael Watterson (IRL)
Editor
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If you click on Create New Model on the Home page you can fill in the form. Afterwards the photos can be uploaded to the Model Page

I'm confused by your comment

Soundwise: very stable rock-solid soundstage, extremely dark background, without slightest dynamic compression.

It's not an amplifier, just industrial voltage regulator for perhaps test equipment in a 19" rack.

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 3
HS86 
12.May.12 11:58
29 from 5789

Allan So (HK)
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Sorry for the confusion, I connect this to my Rohde & Schwarz BN1508 and two 300B integrated amplifiers, the comparison was made with/without the HS86, cheers!

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 4
Blind Test? 
12.May.12 12:07
36 from 5789

Michael Watterson (IRL)
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If you do the test 100 times and have someone behind a curtain change over so you don't know, can you tell (with the Regulator on all the time and a dummy equvilent load so it makes same amount of noise)?

Lovely photos.

 

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 5
Blind test and photo 
12.May.12 12:19
40 from 5789

Allan So (HK)
Articles: 15
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I think so, the filament of the EC81 in the BN1508 is not regulated, and this is crucial for the HF-Teil.

On the other hand, this depends on how bad the mains quality is, which means daytime and weekday give more prominent results (than weekend and night time).

Thanks for the comment on the photos, they are taken with natural overcast light but with shadows, cropped and sharpened a bit.

Cheers!

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 6
EC81 
12.May.12 14:22
66 from 5789

Michael Watterson (IRL)
Editor
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Is it this VHF set?

Is the EC81 on the RF or IF? In which case some +/- 10% mains variation only makes a small change in sensitivity. If it's an Oscillator, no audio effect at all.

If it is in Audio part of circuit then it will only make a change in gain, less change than changing the tube or aging. If there is negative feedback even less change.

Get a number of listeners and your self and do a "blind"* test for an hour with the power changed over many times. Sometimes just momentarily interupted as if changed over, but remaining on the same power.

A second test is to use a "Variac" and measure the performance of the radio objecctively with a test signal and test measurements, not subjectively at variation of 5.7 to 6.9V filament voltage, the normal mains and Regulated supply. To be really sure the person taking the readings should just be told to take a set of measurements and should not know which of the three supplies is used or the filament voltage. The other person (with supplies out of sight) numbers the voltage settings (and measures filament volts on regular mains, variac and regulator) and just tells the first person when to take measurements. Afterwards the filament voltages can be matched to the readings.

Actually I have worked in the BBC, Audio/ Video facilities company doing design and interest in HiFi since 1970s. But I don''t understand "Soundwise: very stable rock-solid soundstage, extremely dark background, without slightest dynamic compression." Can you explain these terms to me and how I would hear these differences on my Saba Meersburg Automatic, Yaesu VR500, Schneider "Romance FM"  Yaesu FT717ND, Sony ICF2001D, Siemens, AEG super bimby luxus 1461 or on any of my modern HiFi?

(*Arranged that the listeners can't know which power is used and can't see the person changing over supply).

 

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 7
Blind test and difference in sound 
12.May.12 17:47
96 from 5789

Allan So (HK)
Articles: 15
Count of Thanks: 10

I know many "audiophiles" who cannot tell the difference between two out-of-phase left and right channel speakers, I also know audiophiles who can accurately tell when different types of fuses are swapped, in double blind tests.

I am not experienced in audio at all, not in studio facilities, I just go to live concerts in various parts of the world, and to various jazz clubs as well.

The answer is simple, live music in concert hall tells us way more than any single piece of glorious equipment.

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