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Jul 24, 2017 12:12:47 GMT
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Would a 42 year old Quadraphonic amplifier repair be of interest to anyone here? It’s got a lot of retro style with wood veneer, brushed aluminium and that designed with a straight edge sharpness. It’s also got that retro charm of an overly complex design coupled with out the box mechanical operation fused together to deliver a failed format of sound delivery. It’s a Quadraphonic amplifier which, if your are not in the know, is THE superior sound format that could have made Stereo systems redundant. It delivers not just the left and right channels of Stereo but two additional channels for Front and Back, this delivers a fully immersive sound output. These systems were really proto-surround sound. The complexity, price probably and format probably kept the format from flourishing. As well as 4 channel CD-4 quadrophony dics it can play SQ discs, which appear to be another format of Quadraphonic encoding. Normal Stereo inputs can be played as 2 channel or also expanded to 4 channel AMBIO which appear to be the poor man’s quadraphonic format. Volume and Tone levels are indicated using fluorescent tape stuck to rubber bands that are wound back and forward by a motor. Radio tuner indication is provided by the same rubber band and tape arrangement but this time actuated with fishing like would back and forward either manually or automatically. I’m having a look at for a relative who has owned the system since new. The problem was explained as that it wouldn’t turn on anymore with the Standby button or remote. It had already been partially dismantled when I first saw it so when I got the unit to work on I rebuilt it with the small pile of screws it came with. There was some additional damage to the internals and I was a few screws short but found suitable replacements in my spares stash. When plugged in the unit did appear to be totally dead, with no lights or sound output or even transformer hum produced. I switched it off and took the covers off it again to try and assess the problem. As it was totally dead the plan of attack was to follow the electrical supply into the unit until I find a fault. Also as there was no schematic I needed to “learn” the layout of the machine and I find this method good for that. My first main concern was with the 1970 spec power supply. The unit takes 240V into the metal chassis (with metal buttons) with no earth connection to the unit at all. I guess this was the norm in 1975, but deaths by faulty electrical equipment were probably pretty common also. To make matters worse the master power switch had exposed terminals and was loosely rattling inside the metal enclosure in a tight space between the power transformer and a bit of shielding. This was an electric shock waiting to happen! 240V (protected with a 13Amp fuse) sits across the solder joints on the switch mounted on the chassis. The switch was loose when I first got the unit and the mains cable tie down was missing! The Power transformer and other conditioning parts were all buried under a shield and other circuit boards. I carefully moved the radio tuner circuitry out the way and found a power smoothing capacitor. This still held 12V so needed discharging before I did anymore prodding around. I used a larger resistor with shielded legs to slowly discharge it. As access was so tight I used my insulated test leads to attach to the capacitor terminals without shorting to anything else. Accessing the power smoothing capacitor terminals wasn't so easy. Discharging the capacitor via the test leads and the resistor at the multimeter. With the capacitor discharged I could move it to gain access to a shield mounting screw, allowing me to remove the shielding from the power transformer. The unit is so tightly packed together access is very fiddly at best. This didn’t reveal anything exciting except the routing of the power wires from the power switch. These ran straight to the voltage selector (I guess I could have figured that out really). The voltage selector cover was removed to reveal 8 terminals, one of the Power Transformer wires had a very black solder joint that I first thought was just dirt in the solder when the joint was made. When I moved the whole voltage selector switch though this joint just snapped apart! That would definitely be a problem! Sorry, a bit out of focus! Voltage selector is the black circular switch that went through the bottom of the chassis. The boards are all soldered together so you can't just unplug a board and remove it. Makes things even more fiddly! Broken joint highlighted though very difficult to see. I soldered this joint back up and put everything back together to see if it was the cause of the issue. As there is no wiggle room for any of the circuitry inside the unit I felt it was best not to power it up without every thing securely in its place. This should avoid any accidental shorts or touching anything live. Plugged in and switched on and we now have power! I did a quick test with headphones and the FM tuner and I got sound although I couldn’t tune a radio station as there was no ariel. There was a lot of missing indicators, including the power LED but at least it turns on! Boom (figurative) we now have power! More to follow, still to sort the indicators and sockets.
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Jul 24, 2017 14:24:28 GMT
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I rememeber back in 1988, I was a porter for a Sofa delivery firm. We had a nice new 3 piece to deliver to a lovely elderly couple in Basingstoke. Whilst bringing it in to the lounge, they had one of these on a special B&O stand - I cracked them up because I asked which one played the organ! Look at it! Awesome piece of kit that you needed a 2nd mortgage no doubt to buy back then.
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96 E320 W210 Wafter - on 18" split Mono's - Sold :-( 10 Kia Ceed Sportwagon - Our new daily 03 Import Forester STi - Sold 98 W140 CL500 AMG - Brutal weekend bruiser! Sold :-( 99 E240 S210 Barge - Now sold 02 Accord 2.0SE - wife's old daily - gone in PX 88 P100 2.9efi Custom - Sold
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zipgun
Part of things
Posts: 109
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Jul 24, 2017 16:49:09 GMT
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Why won't my HH100 amp work anymore then, clever clogs ? At least it lights up pretty pretty green!
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Last Edit: Jul 24, 2017 16:50:34 GMT by zipgun
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Jul 24, 2017 17:16:44 GMT
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Why won't my HH100 amp work anymore then, clever clogs ? At least it lights up pretty pretty green! Lolz, I started out fixing 80's guitar amps. Often its just something obvious like a broken wire or loose multi-pin plug. Amplifiers usually store lethal voltages when switched off though so not always safe to work on.
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zipgun
Part of things
Posts: 109
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Jul 24, 2017 17:59:08 GMT
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About 30 years ago it didn't work and i guess that was something simple ,because the local telly man only charged 4 quid to fix it ! Being left in the shed for the last 20 years probably is the problem now.
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Jul 24, 2017 19:23:09 GMT
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Cutting edge stuff back then and extremely expensive...... good fix!
Most stuff of that era is fixable as no wacky, irreplaceable integrated circuit chips, though finding modern equivalents to 30 year old transistors can be a bit challenging sometimes.
Rarely any dangerous voltages stored in a transistor amplifier once unplugged from the mains - internal working voltages aren't generally more than about 40v unless it's a really powerful one. Valve amplifier or CRT TV though - different story - great care needed.
Nick
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1967 Triumph Vitesse convertible (old friend) 1996 Audi A6 2.5 TDI Avant (still durability testing) 1972 GT6 Mk3 (Restored after loong rest & getting the hang of being a car again)
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Jul 25, 2017 12:50:39 GMT
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Surely the superior sound format is the one that recreates the performance in the way it should be heard. In regards to music that is stereo as all the performers are infront of you. Ok, with quadraphonic you could have an easier time recreating the ambience of the room, but room echo isnt what I want to be hearing. Vast majority of music is better in sterei or mono. If quadraphonic was the way to go, we would still be using it. Maybe if more performers than experimental artists like pink Floyd were creating immersive soundscapes then it would have a home. Didnt The Who have a crack with it to? I'm still in for watching you pull it apart and fix it though
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Jul 25, 2017 16:03:35 GMT
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Update 2: Now that I know it can power up I’m going commit a heinous crime against keeping things original, even though this is a fairly rare and collectible beast. Lowering springs and sexy alloys wait no, 3 wire flex and chassis earth connection, because I like to stay alive. Not a performance enhancing mod but makes me feel a little happier! Cable clamp/grommet also added to that flex going through the chassis. With that out of the way I now want to hear the thing make some noise out of the speaker outputs but the 2 Front Left and Right sockets are broken. To access the backs of the sockets to repair them you have to first move the volume and tone indicators, then loosen the output capacitors before you can gain access to loosen off the speaker jack plate screws. Again it’s a bit hairy as everything is soldered together with no plugs to remove things completely. Undo two screws and the volume and tone displays flip up. Talk about little details that make you smile..... that yellow, red, blue wiring under the indicators is well smart! Backs of the sockets can be see here, the rectangular hole is for the missing Aux socket. The speaker sockets are standard 2 pin din jobs. I don’t have any din plugs or sockets spare so had to order a new socket. While waiting on that to arrive I soldered a temporary set of wires to the backs of the Front Left and Right sockets and ran them back out the chassis through the missing 2 Channel Aux plug. I was struggling for a set of 4 matched speaker cabs, annoyingly enough I’d recently binned 2 pairs of old cabs that I’d hoarded for years. The closest thing I had was an old Marshall 4x12 Cab. I added tails the the backs of this socket and the other Front one as I did have any din plugs handy. I wasn't sure what this board was for, it appears to have a tiny speaker that pokes out the chassis. It turns out it is the receiver for the Ultrasonic remote control. Four nearly matching Celestion speakers from the mid 80's, top two are "keyboard" voiced apparently, bottom two are probably the originals, one has a torn cone for extra retro rasp. I popped the back off the Marshall and tagged on some tails to each speaker to give me 4 separate speakers to plug into the amp. The amp wants 4 ohm impedance speakers but unfortunately the Celestions in the Marshall are 16 ohm. As far as I’m aware this shouldn’t damage the transistor power amp in this machine but it will limit the level of sound output. I rigged up my phone to give me a line out which I had to plug into the Tape 4 Channel input as the 2 Channel aux plug was missing. So powered up and some Metallica input I raised the volume level….. and got no noise at all….. Wired up ready for the test drive... After much checking I found I got stereo through the Front Right and Left Headphone output but nothing else, not even a hiss or a pop out the main speakers. I put this down to the power section being totally rubber ducked. But even with that diagnosis I would have expected at least a hiss or crackle out the speakers. Time to consult the internet, I thought I’d try and at least get some schematics if this was going to get serious.
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Jul 25, 2017 16:16:11 GMT
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Surely the superior sound format is the one that recreates the performance in the way it should be heard. In regards to music that is stereo as all the performers are infront of you. Ok, with quadraphonic you could have an easier time recreating the ambience of the room, but room echo isnt what I want to be hearing. Vast majority of music is better in sterei or mono. If quadraphonic was the way to go, we would still be using it. Maybe if more performers than experimental artists like pink Floyd were creating immersive soundscapes then it would have a home. Didnt The Who have a crack with it to? I'm still in for watching you pull it apart and fix it though I agree with the Stereo vs Quadraphonic argument, it's not really adding anything that the general listener wants anyway. We have surround sound these days but on one has started releasing music in 7.1 format (happy to be corrected on this). It's also like the failed uptake of digital radio, that was thought to be a dead cert after the digital television revolution but it turned out people don't really mind the odd his or crackle when they are purely listening to something.
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MiataMark
Club Retro Rides Member
Posts: 2,954
Club RR Member Number: 29
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Quadraphonic Hi-fi RepairMiataMark
@garra
Club Retro Rides Member 29
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Jul 25, 2017 17:30:03 GMT
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It's also like the failed uptake of digital radio, that was thought to be a dead cert after the digital television revolution but it turned out people don't really mind the odd his or crackle when they are purely listening to something. DAB is a different though as the quality is worse than FM as it's so compressed (or so I believe as I don't actually have a DAB set). In terms of quadraphonic, it was a fad and current surround sound is driven more by cinema sound than HiFi. I do remember wiring speakers up in a hafler configuration to get pseudo quadraphonic from stereo. Great to see the effort going into this, B&O where always the pinnacle of design (if not sound quality). One day I must restore/mod my original NAD 3020 amplifier although it's still doing sterling service connected to the PC. Hafler circuit.
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1990 Mazda MX-52012 BMW 118i (170bhp) - white appliance 2011 Land Rover Freelander 2 TD4 2003 Land Rover Discovery II TD52007 Alfa Romeo 159 Sportwagon JTDm
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Jul 25, 2017 18:28:55 GMT
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Agreed, FM is capable of better sound quality than DAB. wasnt the lack of uptake with dab due to the uk's lack of available space? We were/are? Using a different type of dab to everyone else and don't have enough room.
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Jul 25, 2017 19:35:58 GMT
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Ah fair doo's, I've not heard a DAB set either to be honest, I remember them being advertised as being "clearer" than analogue radio though. I remember hearing a radio interview with some business whizz/entrepreneur type who had invested heavily in DAB radio thinking it to be a gold mine as everyone ditched their analogue sets for digital like they did for TV receivers. Nae luck! Here's another wee update: Ordered some new Lamps from Rapid electronics, the little jiffy bag with the label has the actual parts in it, this jiffy bag was in the bubble wrap bag, which was in the larger jiffy bag, which was wrapped in the paper padding, which was in the box... Packaging probably cost more than the 20 lamps!
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Surely the superior sound format is the one that recreates the performance in the way it should be heard. In regards to music that is stereo as all the performers are infront of you. Ok, with quadraphonic you could have an easier time recreating the ambience of the room, but room echo isnt what I want to be hearing. Vast majority of music is better in sterei or mono. If quadraphonic was the way to go, we would still be using it. Maybe if more performers than experimental artists like pink Floyd were creating immersive soundscapes then it would have a home. Didnt The Who have a crack with it to? I'm still in for watching you pull it apart and fix it though But that also presupposes that the stereo studio mix is the right sound, it's not what you would hear if you went to a concert. Surround / quadrophonic / ambisonic sound should give you a more immersive feeling when used right. This is especially true for things like classical music, where it is as much to do with the interaction of the instruments and the room, as it is the people playing them.
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MiataMark
Club Retro Rides Member
Posts: 2,954
Club RR Member Number: 29
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Quadraphonic Hi-fi RepairMiataMark
@garra
Club Retro Rides Member 29
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For true reproduction of a live performance, what you need is binaural recording and headphones...
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1990 Mazda MX-52012 BMW 118i (170bhp) - white appliance 2011 Land Rover Freelander 2 TD4 2003 Land Rover Discovery II TD52007 Alfa Romeo 159 Sportwagon JTDm
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For true reproduction of a live performance, what you need is binaural recording and headphones... with individualised HRTFs for true localisation.
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MiataMark
Club Retro Rides Member
Posts: 2,954
Club RR Member Number: 29
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Quadraphonic Hi-fi RepairMiataMark
@garra
Club Retro Rides Member 29
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For true reproduction of a live performance, what you need is binaural recording and headphones... with individualised HRTFs for true localisation. Just looked that up, still confused! Does it allow you to play a binaural recording through speakers or is it to 'individualise' binaural recordings for playback? I'm worried about my 'cone of confusion' now.
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1990 Mazda MX-52012 BMW 118i (170bhp) - white appliance 2011 Land Rover Freelander 2 TD4 2003 Land Rover Discovery II TD52007 Alfa Romeo 159 Sportwagon JTDm
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Head Related Transfer Functions measure the effect of your head shape, outer ear (pinna) and ear canal on the sound from a given direction. Binaural recordings tend to use either a dummy head with a generic set of ears, or a multichannel microphone array convolved with generic transfer functions. This means that whilst it might sound good to some people, to others the localisation will be miles off. Individual measured HRTFs take that out, and make things work for your ears. For the best localisation I would go with custom measured HRTFs, and in-canal headphones... Things get more complex from here on it
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Jul 26, 2017 15:16:34 GMT
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Surely the superior sound format is the one that recreates the performance in the way it should be heard. In regards to music that is stereo as all the performers are infront of you. Ok, with quadraphonic you could have an easier time recreating the ambience of the room, but room echo isnt what I want to be hearing. Vast majority of music is better in sterei or mono. If quadraphonic was the way to go, we would still be using it. Maybe if more performers than experimental artists like pink Floyd were creating immersive soundscapes then it would have a home. Didnt The Who have a crack with it to? I'm still in for watching you pull it apart and fix it though But that also presupposes that the stereo studio mix is the right sound, it's not what you would hear if you went to a concert. Surround / quadrophonic / ambisonic sound should give you a more immersive feeling when used right. This is especially true for things like classical music, where it is as much to do with the interaction of the instruments and the room, as it is the people playing them. Stereo mix is a a mess of a subject. Some times the stereo is purely for effect and was always intended as such, sometimes they are trying to force a false image, sometimes they are trying to preserve the original soundscape. Sometimes I just want to hear exactly what the audio mixer intended, sometimes your trying to ignore that to imagine what might have been. Its a mess. I have some great records that bypass the lot by being double mic recordings cut direct to disc with no master tape. They are amazing! Personally, I'm not one for imersive sound. I cant stand wearing headphones/earphones and dislike surround sound. I have just settled in the philosophy of just trying to reproduce exactly whats on the disc, good or bad. Unfortunately that renders half my records unlistenable! (I'm also not interested in any kind of sound correction or tone alteration). However, when everything is right, its very much worth the grief. Sonetimes I wish I could bring myself to just have all the music I wish on digital files and have a system that allows a passable reproduction of everything.
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Jul 27, 2017 19:28:17 GMT
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Update 3: Always read the instructions I tried to find some free schematics online but the best I could get were illegible and in German (probably Danish actually, I can’t read either though so moot point). There also appears to have been a much more popular 2 Channel version of the Beomaster 6000 as I kept finding files relating to it. Unfortunately it appears to be a completely different machine. I found places where could pay for a schematic but I was sceptical that these would be any better to the free one’s as the files listed were the same name and size to what I had already found. (been caught out with this before too) I did find an operator’s manual. This turned up to be more useful than any wiring diagrams anyway, containing information on the different quadraphonic formats and more importantly how to actually use the amplifier. I liked this statement in manual: Maybe I should get the B & O dealer out to help...... So a recurring thing I noticed in the manual was that after you select you input like “Aux 2” or “Tape 4” you then select the speakers you want to play through by setting either Front speakers “On” and/or Rear speakers “On” and then setting the Stereo, Ambio or Quadraphonic delivery. I’d been skim reading through the manual before this sunk in…... I hadn’t actually turned on any of the speaker when I tested the unit. Oops! Who knew there were ON/OFF buttons for the speakers!! "FRONT" and "REAR" buttons turn the output to the speakers on or off. I went straight back out to the shed and fired the amp back up, this time switching the front speakers ON. With that we now have sound output!!!! The manual explained that with a Stereo input by turning on the Rear speakers and then using the “Stereo” or “Ambio” buttons I could play back using all four speakers. This fired up all four of the Marshalls speakers with that lovely well rounded, bassy but crystal clear vintage HiFi tone. Now that I’m happy the beast is alive I’ll tackle some of the other more cosmetic/mechanical defects: 3 x missing rubber feet 8 x indicator lamps blown Power LED indicator intermittent operation?? FM tuner wheel shaft bent FM display indicator lamp supply wires snapped FM tuner cord snapped FM tuner indicators not latching on Broken socket - Aux 2 Channel Broken socket - Front Right Speaker Broken wood trim Aluminium front switching panel is isolated from chassis and not earthed
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You lost me after the opening paragraph, but I'm still enjoying the tale!
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