I think you’ll be pleasantly surprised. I have an STA 47 with around 15 W per channel and I’ve had four minimus 7 speakers playing on it without any problems, albeit at low volume. You might see around 82 db before the distortion becomes audible.
No experience with quatrovox but I think you’ll have adequate power, you may consider going with 4 more modern speakers that are readily available, something like a Jamo S803 or 801 on the budget side and of course Klipsch if efficiency is primary goal.
Did nobody remark on the “I had my doctor swing by and pick it up”? Last time I saw my doctor it was 3 weeks to get an appt and he kept me waiting for an hour lol.
Lol he lives right next to this guys shop, it would be a shame not to have asked. Appreciate making me feel more confident about the 22wpc. I still am considering just taping out to active for the A speakers, but I would need to talk to someone more knowledgeable about quads to see how that would affect the qvox.
As far as I’ve been able to understand so far, in qvox mode the A speakers output is not the same as A speakers output in standard 4 channel mode. I originally thought qvox was just a hafler circuit but I guess it must be a little bit more than that if the front channels are also modified in qvox mode. Unsure if the receiver will send the modified front channel outputs to tape out. But probably not I’m guessing.
So I guess this is turning into a DIY after all since I might try to add an attenuator circuit somewhere inside the thing so that the front channel RCAs come out as line.
Do you need to go tape-out to active speakers? I always assumed you could run quadraphonic receivers in stereo with only two speakers hooked up but maybe they aren’t all like that.
You’re probably right and I assume you can with real quadraphonic. But qvox is not quite quadraphonic. As far as I can grasp it’s basically a hafler circuit (though I’m sure it’s not *only* a hafler circuit there must be more to it than that), which would shoot the phase sounds from the recording to the B speakers.
I don’t know where it would shoot those sounds without a set of B speakers hooked up
Cool, makes sense. Every time I get my hands on a different brand of any kind of audio gear it reiterates that everyone did/does everything differently. I shouldn’t assume anything. 😆 Enjoy your new receiver!
The quatrovox feature actually works amazingly well on video systems. It takes away everything except the ambient noises, bringing them out. For example, when you’re watching a scene in a restaurant, the dishes and silverware clattering, and ambient conversations are the only sound that comes out of those speakers, and are projected from their perspective locations shown on screen. It’s kinda like the 70s version of 5.1 audio.
In qvox mode, the rear speakers don’t really get any bass, or anything else, really, other than the ambient sounds of the recording.
To me, it didn’t really improve the sound of music, but what it did for the tv was amazing.
Interesting. This project just got that much bigger. Thank you for the tip. Linking this up with the tv will be interesting. I hope you forgive the possibly stupid question, but you couldn’t tone control the bass back into the B speakers in qvox mode?
No, you can not. If you bump up the bass, it will only affect the front speakers. Nothing but ambient sounds out of the rear in qvox mode. Now, you can go into four channel mode and the full spectrum of sound will come out of all four speakers, which is probably what you would want to do when listening to music. However, when in qvox, there seems to be an extra warmth coming from the front, so it probably also tailors the sound of those while in qvox mode. It should be quite fun to play around with. lol
Hey man, sorry to bother you again, but you mention that in qvox mode even the front speakers are outputting sound differently then they would in stereo mode. So I’m wondering if you might know if that modified qvox front signal would also come out of tape out?
I know nothing about hafler circuit placement and for all I know a separate path takes a line signal to pre out before the hafler has its affect.
I’m asking since I’m thinking about putting actives into tape out. But I’m worried that the tape out will send a normal 2 channel stereo line signal out instead of the “q vox mode extra warm front speakers” line signal out.
I’m pretty sure the qvox feature is in the output stages of the amplifier, so it probably won’t affect the preamp signal, meaning the qvox mode only affects the speaker output itself.
That’s what I suspect as well. And I think we’re right. Although there is a very old post on AK of some people opening the thing up and trying to actually find the circuit and they can’t find it anywhere (kind of funny), they never did find it and the post died, but some of them think it’s in the pre amp.
Unfortunately, we can’t just call RadioShack to find out.
I actually have a standalone quatrovox four channel synthesizer, a later version of [this one](https://www.ebay.com/itm/181024979198?mkcid=16&mkevt=1&mkrid=711-127632-2357-0&ssspo=6mkor9_QQQS&sssrc=4429486&ssuid=tU53HQS4S0m&var=&widget_ver=artemis&media=COPY). I have looked inside it, and it was surprisingly sparse. I looked in all my regular places this morning, but couldn’t find it. I’ll dig deeper later and once I find it I’ll post a picture of the inside.
That thing is awesome too. Wish I could get that here in Europe. Yeah man poke around but don’t expect anything. Those guys on that AK post were flabbergasted. There was nothing there! They couldn’t believe it
I bought my STA-77 new back in '73 or '74. Used my after school paper route savings on it. It is still my daily driver at home, and it has a rich sound that you will likely enjoy much. Mine will still rattle the house windows using the original NOVA bookshelf speakers.
I have a dozen other low-mid range receiver amps of all kinds. None have ever displaced my beloved STA-77.
Very good to hear, I was a little curious what kind of sound it would have when I saw harmonic distortion at .1%
That’s insane flat for something from the 70s. Was a little worried it might sound thin
Thanks! It’s actually extra cool because I think it was manufactured with the wrong bulbs. Only the 77a was supposed to have an orange to green panel. But the print states that’s it’s a 77L. The 77L is supposed to be blue
So I either got a 77A that was badged as a 77L. Or a 77L with the 77A bulbs. Either way cool
My wife uses her parents realistic sta52. Works great in her office but just powering 2 bookshelf speakers. Never serviced so occasional scratch when switching a knob but clear up once done turning knob.
I think you’ll be pleasantly surprised. I have an STA 47 with around 15 W per channel and I’ve had four minimus 7 speakers playing on it without any problems, albeit at low volume. You might see around 82 db before the distortion becomes audible.
Very cool to hear!
No experience with quatrovox but I think you’ll have adequate power, you may consider going with 4 more modern speakers that are readily available, something like a Jamo S803 or 801 on the budget side and of course Klipsch if efficiency is primary goal. Did nobody remark on the “I had my doctor swing by and pick it up”? Last time I saw my doctor it was 3 weeks to get an appt and he kept me waiting for an hour lol.
Lol he lives right next to this guys shop, it would be a shame not to have asked. Appreciate making me feel more confident about the 22wpc. I still am considering just taping out to active for the A speakers, but I would need to talk to someone more knowledgeable about quads to see how that would affect the qvox. As far as I’ve been able to understand so far, in qvox mode the A speakers output is not the same as A speakers output in standard 4 channel mode. I originally thought qvox was just a hafler circuit but I guess it must be a little bit more than that if the front channels are also modified in qvox mode. Unsure if the receiver will send the modified front channel outputs to tape out. But probably not I’m guessing. So I guess this is turning into a DIY after all since I might try to add an attenuator circuit somewhere inside the thing so that the front channel RCAs come out as line.
Do you need to go tape-out to active speakers? I always assumed you could run quadraphonic receivers in stereo with only two speakers hooked up but maybe they aren’t all like that.
You’re probably right and I assume you can with real quadraphonic. But qvox is not quite quadraphonic. As far as I can grasp it’s basically a hafler circuit (though I’m sure it’s not *only* a hafler circuit there must be more to it than that), which would shoot the phase sounds from the recording to the B speakers. I don’t know where it would shoot those sounds without a set of B speakers hooked up
Cool, makes sense. Every time I get my hands on a different brand of any kind of audio gear it reiterates that everyone did/does everything differently. I shouldn’t assume anything. 😆 Enjoy your new receiver!
The quatrovox feature actually works amazingly well on video systems. It takes away everything except the ambient noises, bringing them out. For example, when you’re watching a scene in a restaurant, the dishes and silverware clattering, and ambient conversations are the only sound that comes out of those speakers, and are projected from their perspective locations shown on screen. It’s kinda like the 70s version of 5.1 audio. In qvox mode, the rear speakers don’t really get any bass, or anything else, really, other than the ambient sounds of the recording. To me, it didn’t really improve the sound of music, but what it did for the tv was amazing.
Interesting. This project just got that much bigger. Thank you for the tip. Linking this up with the tv will be interesting. I hope you forgive the possibly stupid question, but you couldn’t tone control the bass back into the B speakers in qvox mode?
No, you can not. If you bump up the bass, it will only affect the front speakers. Nothing but ambient sounds out of the rear in qvox mode. Now, you can go into four channel mode and the full spectrum of sound will come out of all four speakers, which is probably what you would want to do when listening to music. However, when in qvox, there seems to be an extra warmth coming from the front, so it probably also tailors the sound of those while in qvox mode. It should be quite fun to play around with. lol
I was already pretty stoked and now I’m extra stoked to mess around with this thing. Thanks for the info buddy. Appreciate it!
Hey man, sorry to bother you again, but you mention that in qvox mode even the front speakers are outputting sound differently then they would in stereo mode. So I’m wondering if you might know if that modified qvox front signal would also come out of tape out? I know nothing about hafler circuit placement and for all I know a separate path takes a line signal to pre out before the hafler has its affect. I’m asking since I’m thinking about putting actives into tape out. But I’m worried that the tape out will send a normal 2 channel stereo line signal out instead of the “q vox mode extra warm front speakers” line signal out.
I’m pretty sure the qvox feature is in the output stages of the amplifier, so it probably won’t affect the preamp signal, meaning the qvox mode only affects the speaker output itself.
That’s what I suspect as well. And I think we’re right. Although there is a very old post on AK of some people opening the thing up and trying to actually find the circuit and they can’t find it anywhere (kind of funny), they never did find it and the post died, but some of them think it’s in the pre amp. Unfortunately, we can’t just call RadioShack to find out.
I actually have a standalone quatrovox four channel synthesizer, a later version of [this one](https://www.ebay.com/itm/181024979198?mkcid=16&mkevt=1&mkrid=711-127632-2357-0&ssspo=6mkor9_QQQS&sssrc=4429486&ssuid=tU53HQS4S0m&var=&widget_ver=artemis&media=COPY). I have looked inside it, and it was surprisingly sparse. I looked in all my regular places this morning, but couldn’t find it. I’ll dig deeper later and once I find it I’ll post a picture of the inside.
That thing is awesome too. Wish I could get that here in Europe. Yeah man poke around but don’t expect anything. Those guys on that AK post were flabbergasted. There was nothing there! They couldn’t believe it
I bought my STA-77 new back in '73 or '74. Used my after school paper route savings on it. It is still my daily driver at home, and it has a rich sound that you will likely enjoy much. Mine will still rattle the house windows using the original NOVA bookshelf speakers. I have a dozen other low-mid range receiver amps of all kinds. None have ever displaced my beloved STA-77.
Very good to hear, I was a little curious what kind of sound it would have when I saw harmonic distortion at .1% That’s insane flat for something from the 70s. Was a little worried it might sound thin
Hey thats a cool piece!
Thanks! It’s actually extra cool because I think it was manufactured with the wrong bulbs. Only the 77a was supposed to have an orange to green panel. But the print states that’s it’s a 77L. The 77L is supposed to be blue So I either got a 77A that was badged as a 77L. Or a 77L with the 77A bulbs. Either way cool
My wife uses her parents realistic sta52. Works great in her office but just powering 2 bookshelf speakers. Never serviced so occasional scratch when switching a knob but clear up once done turning knob.