Hi, semi newb here. I bought a pioneer 4 channel receiver mod # QX-747. It plays but some outputs don't work correctly, all knobs are very scratchy or plane not working? I did some research and at the least it probably needs all new caps at over $75 for parts and a tone of hours. I was going to try deoxit to see if that improves the general workings somewhat but haven't opened it up yet.
Is the sound from this old amp when new worth the effort? Nostalgia be damned, it's about sound quality, although it is rather cool looking front with a target like thing that lights up about the quadrophonic output?
Or????? I was thinking about gutting the boards and using maybe the power supply, heatsinks? Not sure what it is but it weighs a tone. And building say a gain clone or something to fit inside of it? Maybe, hopefully a budget clone from China of a respectable design of some sort? If it exists? Thinking N Pass clone, Naim clone, or?? Don't want to go much over the $100 US mark. I have built several tpa3116, 8932, and a few other amp modules but looking for better sound. There is something I don't care for sound wise with each of the previous class d amps I made, usually a little shouty? Admittedly I have not tried any mods, just stock boards.
So, what do you think? Fix, or gut the sucker? Anyone know what the power supply is inside this thing? The front and case is in pretty good shape with all the knobs. I paid $5 in garage sale so not in too deep. Which amp module would you use and why? Thanks for all replies. I humbly apologize if I posted in wrong forum. I picked it because I was thinking LM 3886?
Is the sound from this old amp when new worth the effort? Nostalgia be damned, it's about sound quality, although it is rather cool looking front with a target like thing that lights up about the quadrophonic output?
Or????? I was thinking about gutting the boards and using maybe the power supply, heatsinks? Not sure what it is but it weighs a tone. And building say a gain clone or something to fit inside of it? Maybe, hopefully a budget clone from China of a respectable design of some sort? If it exists? Thinking N Pass clone, Naim clone, or?? Don't want to go much over the $100 US mark. I have built several tpa3116, 8932, and a few other amp modules but looking for better sound. There is something I don't care for sound wise with each of the previous class d amps I made, usually a little shouty? Admittedly I have not tried any mods, just stock boards.
So, what do you think? Fix, or gut the sucker? Anyone know what the power supply is inside this thing? The front and case is in pretty good shape with all the knobs. I paid $5 in garage sale so not in too deep. Which amp module would you use and why? Thanks for all replies. I humbly apologize if I posted in wrong forum. I picked it because I was thinking LM 3886?
I don't know (or at least remember) that model, but none of that vintage of Pioneer receiver ever got me excited. I think you'd find that deoxit on all the switches and controls will do wonders for the scratchies and the intermittents -- I remember Pioneers around then used some really junky toggle switches which went intermittent after only a few years from new -- get some deoxit on their contacts (not always easy) and they will go for a few more (I used to be a repair tech back in the day).
If you were to use its carcass as a base for building new inside, which modules or designs to use will depend on the power supply voltages (assuming you'd be keeping that). The most likely caps to need replacing would unfortunately be the big power supply filter caps (they're about the only ones that really get stressed), but you can probably find a usable type replacement at a decent price on ebay -- electrolytics have gotten more compact since that amp was made (you do NOT want "new old stock"/NOS). Other caps might have gotten leaky or changed capacitance, but less likely I think.
If I were doing it, I'd probably put in some Hypex or ICEpower modules, but since you don't seem to like class D, maybe some LM3886? Assuming the supply voltage is appropriate.
If you were to use its carcass as a base for building new inside, which modules or designs to use will depend on the power supply voltages (assuming you'd be keeping that). The most likely caps to need replacing would unfortunately be the big power supply filter caps (they're about the only ones that really get stressed), but you can probably find a usable type replacement at a decent price on ebay -- electrolytics have gotten more compact since that amp was made (you do NOT want "new old stock"/NOS). Other caps might have gotten leaky or changed capacitance, but less likely I think.
If I were doing it, I'd probably put in some Hypex or ICEpower modules, but since you don't seem to like class D, maybe some LM3886? Assuming the supply voltage is appropriate.
Didn't say I didn't like class D but I see how u could deduce that from my post. I like them OK, was just hoping for better. It's hard to decide because I've not heard anything else. I have want-to-build-itis. It's a disease I am afflicted with! Been lurking for some time now, dreaming of the Pass labs, Elliot sound, etal, amps and their wonderful praises. But alas, the budget won't allow it. That's why I use cheap Chinese class D and have enjoyed their easy implementation into quick easy projects. I even have a little two tube pre that I like in front of the 3116. I was just hoping someone would say, yah, use the chassis and PS of the old receiver and get a couple of ???????Insert good budget modules, and u have a true audiophile/ hi-fi setup? Your post is very informative and gets me thinking I might just try cleaning contacts,pots,etc and checking the big power caps if bulging or leaking and give a listen? I did like the old marantz and Harmon Kardin stuff of the same era? Around 1970's I think? Thanks for your input
Just checked the ice power and hypex modules on eBay. Which do u like, I tend toward the ice power as the one I checked has ps built in, just add AC power and inputs. But the bang olefson name trips an unobtanium switch in my head from my past. Those things were very sexy, sounded great, and they cost more than my first two or three cars!
So, no interest. I purchased two boards, the TPA 7498 and the TPA 7498E with look alike mean well clone power supplies. Might be a month, but will give it a go and compare to 3116, 3118, 8932, 2497, and Pepsi 2024a+ amp modules
I am interested as I have a couple of old receivers which could benefit from an upgrade.
Thanks,
Robert
Thanks,
Robert
I would leave it stock, but fix it up, re-cap at some point in time, change some bjts that are known problems. deoxit the switches, fader lube the controls. there is a lot more info at audiokarma, check out the pioneer forum. hifiengine has the manuals.
I have a qx-9900, wonderful looking piece of gear from the past. that is what I will doing to mine.
I have a qx-9900, wonderful looking piece of gear from the past. that is what I will doing to mine.
Thanks rsavas
So how is the sound quality? I like the retro look. Especially since all the lights work. But the previous poster never like the sound? Would you have a link to more info on repairing this amp? Would be a cool winter project? Thanks for input.
So how is the sound quality? I like the retro look. Especially since all the lights work. But the previous poster never like the sound? Would you have a link to more info on repairing this amp? Would be a cool winter project? Thanks for input.
Everyone has their opinions. Sure the amps are older designs, of course they can be improved upon if that is what you want to do. Like I said go to audiokarma.com/pioneer. I my self have not investigated all the posts for this model. If you post on AK I can answer all your ?'s, so others have the same insight. We can get a BOM together if you want to refrib the unit.
Wow!
That is an offer I can't refuse! I did go to audio karma but forgot my password, so as soon as I reset I will be there! Thanks! A ton
That is an offer I can't refuse! I did go to audio karma but forgot my password, so as soon as I reset I will be there! Thanks! A ton
See you there.
BTW, TPA3116 and these other TI class D amps all have floating outputs.
Most class AB amps reference ground, the speaker jacks are hard wired to ground. Big job to isolate the grounds. Not something I suggest you do.
BTW, TPA3116 and these other TI class D amps all have floating outputs.
Most class AB amps reference ground, the speaker jacks are hard wired to ground. Big job to isolate the grounds. Not something I suggest you do.
Thanks, you have answered my original post to a T. I will, with esteemed guidance attempt to revive the 1970's player. I was born 1960 so I grew of age in the 70's, and this tech was good stuff back then, so was I, lol. I am not done yet and neither should this vintage equipment. Thanks again rsvas
I am 1 year older. I remember me and my bro going over to the rich uncles place, he bought his kids the quad pioneer setup. not sure if it was the qx-949 or the one you have. we were blown away when they played pink floyd in quad, so much so that when we got the funds together we bought our first pioneer stereo, a sx-950. both of us worked all summer at $2.65/hr to buy the gear, still have it today, still rocks the house down. 🙂
Haha, memories! I remember in college my roommate had Bose 301's don't remember the head unit? But Pink Floyd's song with choppers had me looking out the window for them. Was just after the botched rescue of Americans from the Iran affair! I think I was helped by some redbud! Oops. All signed up at audio karma and downloaded the manuals from audio engine. Thanks, tournament winner!
Ahhh yes! Not the exotics of today. But was good, cheap, 5 fingers!!!!! Don't forget $20 Mexican, memories light the corners of my mind
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