What do those Tone Presets really look like? - Tube Radio Restoration Back to Basics part 7

[@DavidTipton101]

I missed a video... great explanation Manuel and now it has a name, psychological loudness or psychoacoustics, nice conversation starter 👍🙂

[@electronicsoldandnew]

😊 I’d like to see the reaction

[@randomsteve4288]

One of the things that the tone shape buttons do, which is lost in this experiment, is that they introduce not only attenuation but also phase shift within a the spectrum. This in turn will interact with the filters placed around the speaker and tweeters and with the positioning of the speakers in the cabinet it will eventually create an audible spacial illusion of sound distribuition. This was taken to a max by Graetz on their Super 3D HiFi radios which even used a horn speaker resonating into tubing to create spatial sound illusion. Similar methods of tone shaping with phase shift networks in an effort to create pseudo stereo from mono, were revived in the 80s and discussed in length by (among others) Elektor hobby electronics magazine and also used in some stereo TV as "pseudo stereo" option (among others Grundig CUC 720 and Schneider Chassis TV1)

[@electronicsoldandnew]

👍

[@petersdelucaaa2vg306]

Manuel. Good timing. I’m doing the tone shaping section of a Blaupunkt Verona that I am restoring now. This helps me better understand things. Great demonstration on the computer.

[@electronicsoldandnew]

👍 good luck with your Verona

[@josephmagedanz4070]

Wow...I have so much that I still need to learn! Thank you very much for taking the time and effort to explain all of this and to make these videos. Much appreciated!

[@electronicsoldandnew]

My pleasure

[@JonRig]

Great video, as always. The tone shaping that they did on these radios is really fascinating. It's why, to this day, they sound so good!! I am assuming your workroom must smell like a distillery after a good cleaning session!!! 😂

[@electronicsoldandnew]

Can’t tell. Too drunk to notice 😊

[@ralphj4012]

Interesting. Not sure if you can change the vertical scale on visual analyser, the buttons seem to be introducing roughly a 3dB change, which would certainly be audible. Love how just a cleaning exercise can change a socket (2:40) into a plug (11:08), ho, ho.

[@electronicsoldandnew]

Cleaning performs miracles 😊

[@deepblueskyshine]

Loudness compensation is not a psychological but rather physiological phenomenon: as mentioned our hearing of very high and very low frequencies is less sensitive than to the range of frequencies our voices and our simple musical instruments produce, so much so that listening to quiet relaxing level of music recorded at much louder levels highs and lows drop below hearing threshold and sound losses its richness. It is also good to remember that loudness perception is about the sound pressure at the eardrums, but the volume pot, tone compensation circuits and switches affect electric signal amplification and how the resulting electrical power is transfered into sound pressure by the loudspeakers and the many paths the sound travels to a pair of ears are several different stories.

[@electronicsoldandnew]

👍

[@Indiestereographer]

The absolute simplest and best substance for cleaning "finger fat" off knobs and buttons is a concentrated mix of washing up liquid and water, use an old toothbrush, it's fast and cleans brilliantly. Application of isopropyl alcohol can easily alter these old plastics, print and finishes, I've been doing this for years with fast and perfect results.

[@electronicsoldandnew]

👍

[@tubeDude48]

Did I miss-read your reading at 15:00? It looked like you were in ohms, rather then reading that CAP in Capacitance. At 23:40, could be the 470K CAP being off so much in value is effecting those small changes, when they could be more pronounced? Those Germans, as you said), did a hell of a job at creating this part of the circuit! And your explanation of this part of the circuit has been excellent!

[@electronicsoldandnew]

I wasn’t reading anything at that point. Just eyeballing the cap connections

[@tubeDude48]

@@electronicsoldandnew - OK, but I though you were reading across the CAP for a value. Oh well, my mistake.

[@BobAndersson]

Thanks Manuel, great job! I suspect you spent a great many hours collating all those various plots into that slick presentation. Am I the only one who came to these radios as a neophyte expecting the bass and treble controls to be able to significantly boost their part of the audio spectrum as well as attenuate it? 🤣 But that's how they mostly seemed to do it back in the day and I'm used to it now. I was a tad confused by the Orchester button though - isn't it just acting to mechanically cancel the other selections, Bass excepted of course. I didn't notice it in the schematic.

[@electronicsoldandnew]

You’re probably right. I didn’t check the actual effect of all the buttons

[@donhall2759]

Very helpful to use the spectrum analyzer for this! I can't help but notice the brick wall at 10khz; was that the bandwidth of your test signal or the audio response of the receiver? I would have expected a more extended response, especially on the phono input, with the quality tweeters included on this set. Also, I wonder if the preset tone switches have different effects at different settings of the volume control.

[@electronicsoldandnew]

That’s the upper limit that I set for the sweep as mentioned in the video.

[@mackfisher4487]

Manuel, you may have convinced me to purchase an airbrush paint sprayer system. I don't think you've shown in detail how well it cleans in this episode the piano keys is a great illustration. I may have to give up chopsticks.

[@electronicsoldandnew]

😊 I always keep a few chopsticks in reserve 😊

[@daveturner5305]

Manuel is the apparent 10k cut off a limitation of the software? I would have thought that the frequencies above 10k would be relevant especially for orchestra based music, particularly for FM. I do appreciate that the spread is limited due to the horizontal scale though.

[@electronicsoldandnew]

Yes, the rather precarious connections were giving me strange oscillations at higher frequencies, so I limited the span.

[@daveturner5305]

@@electronicsoldandnew Perhaps you could repeat the test, or a similar one, once the restore is complete. Regards dave

[@electronicsoldandnew]

It’s not the radio, it’s the fact that I’m reading from the power tube itself.

[@TheEmbeddedHobbyist]

I stick to IPA as we have to buy ethanol in the UK as Mentholated spirits which might leave a purple stain on things. it has a purple dye added to try and put people off from drinking it.

[@electronicsoldandnew]

Yes, I remember that from South Africa.

[@DavidSmith-zx7wz]

Can I ask where the chassis stands come from?

[@electronicsoldandnew]

Made it myself

[@ricardoaliasdelatorre6836]

Nice video Manuel, a quick course about slope filtering and its dB/Hz features.By the way I agree with @fotoralf, why not test it till 15Khz?.(for the next time..) cause audio from FM radio has more process & enhancement.

[@electronicsoldandnew]

When you put a probe at the anode if the power tube (especially when the probe is sort of DIY), oscillations can happen, and they did in this case at frequencies closer to the 20kHz

[@ricardoaliasdelatorre6836]

👍ok, Manuel , has all the sense, testing the power tube not blowing it in a "open system " without NFB

[@fotoralf]

Why not measure up to 15 or even 18 kHz? FM radio normally carries audio frequencies up to 15 kHz and the radio's audio stages certainly go that high.

[@DavidSmith-zx7wz]

With this kind of content, your subscriber rate should be up to about 100K to 200K at least!! I don't understand?

[@electronicsoldandnew]

That doesn’t really bother me. The important thing is that someone like you is one of the subscribers 👍 Also, with huge numbers of subs comes a huge number of rather unpleasant interactions, which we’ve verbally managed to avoid on this channel so far.

[@DavidSmith-zx7wz]

@@electronicsoldandnew Well for me, the way you explain every little detail and how it works what it does is very nice for someone that is still learning. Thanks for what you do!

[@electronicsoldandnew]

Pleasure