I'm considering getting some second-hand amps for use in an actively crossed system. Attenuation will be at source (i.e. any amp volume control would remain set high) so I'm particularly keen that they're fairly low noise. I could consider AVRs, but IMO the ideal contenders would be power amps (or integrated amps with a by-passable pre-stage); most seem to have a SNR around 115dB or better.
I am tempted by used models from NAD such as the C326BEE, which can be got for about £200 here. But even though not massively old (15years?) they seem to have quite a lot of reliability issues being tackled on diyAydio. Things like protection circuits, overheating zeners, and electrolytics placed close to hot parts. Some Rotel power amps like the RB-970BX appear to have better build quality, and so might be more suited to maintaining as they age. For similar money they're already quite a lot older to begin with, though.
So i'm now wondering if the second-hand route is sensible, or likely to incur frequent and ongoing maintenance problems. I'm up to replacing old capacitors, though probably not skilled enough to diagnose any tricky faults that might develop. But (obviously) I'm no expert so wondered what more informed people on here think about this - plain daft, better choices etc?
Thanks, Kev
I am tempted by used models from NAD such as the C326BEE, which can be got for about £200 here. But even though not massively old (15years?) they seem to have quite a lot of reliability issues being tackled on diyAydio. Things like protection circuits, overheating zeners, and electrolytics placed close to hot parts. Some Rotel power amps like the RB-970BX appear to have better build quality, and so might be more suited to maintaining as they age. For similar money they're already quite a lot older to begin with, though.
So i'm now wondering if the second-hand route is sensible, or likely to incur frequent and ongoing maintenance problems. I'm up to replacing old capacitors, though probably not skilled enough to diagnose any tricky faults that might develop. But (obviously) I'm no expert so wondered what more informed people on here think about this - plain daft, better choices etc?
Thanks, Kev
The stereo I had growing up was an early/mid 1970s B&O integrated amp/turntable. By the late 1980s the transistor in the Vbe multiplier failed. I swapped it out and the amp came back to life. That stereo ended up at my grandfather's where it saw regular use until 1998 when he died. So at least my experience with 'vintage' amps has been pretty good.
My dad was deep into the B&O systems, in particular those of the late 70s and early 80s. His last B&O system ran for 30+ years before he sold it.
I'm not suggesting there's anything special about the B&O circuits. In fact, there isn't. I'm just using it as an example of a discrete, vintage amp that - at least based on my personal experience - seemed to last about forever.
If you go the 'vintage' route be mindful of custom ICs. If the amp has some custom module in it, it'll be a pain to repair. Discrete amps and amps based on standard opamps and chip amps can be repaired as long as you can get parts. I wouldn't worry too much about failures, but at the same time all electronics will fail eventually. It's probably more important to buy an amp that's been treated well, i.e., one that's been kept dry and at room temperature year round. Not one that's had water/humidity damage or some sort of critter infestation.
Tom
My dad was deep into the B&O systems, in particular those of the late 70s and early 80s. His last B&O system ran for 30+ years before he sold it.
I'm not suggesting there's anything special about the B&O circuits. In fact, there isn't. I'm just using it as an example of a discrete, vintage amp that - at least based on my personal experience - seemed to last about forever.
If you go the 'vintage' route be mindful of custom ICs. If the amp has some custom module in it, it'll be a pain to repair. Discrete amps and amps based on standard opamps and chip amps can be repaired as long as you can get parts. I wouldn't worry too much about failures, but at the same time all electronics will fail eventually. It's probably more important to buy an amp that's been treated well, i.e., one that's been kept dry and at room temperature year round. Not one that's had water/humidity damage or some sort of critter infestation.
Tom
Thanks Tom, that sounds like very reasoned thinking, and encouraging, too. Though yes, of course one could be unlucky with any bit of kit - even new stuff that is slightly out of warranty.
Probably (and as usual) I'm therefore also being too analytical about it. If I buy something that I actually like, then I will actually enjoy owning it and take some satisfaction in keeping it running. Happily I'm old enough to have lusted after amps that are still very decently specified and yet are now old and cheap, so there is a head-start.
Thanks again, Kev.
Probably (and as usual) I'm therefore also being too analytical about it. If I buy something that I actually like, then I will actually enjoy owning it and take some satisfaction in keeping it running. Happily I'm old enough to have lusted after amps that are still very decently specified and yet are now old and cheap, so there is a head-start.
Thanks again, Kev.
Yes, probably. But without increasing the budget they would be quite compromised - either in their sonic performance or be relatively fragile desktop types (and probably class-D which I personally wouldn't have much chance of repairing). Which doesn't exclude the possibility; there are compromises in any choice.
In the past I've built my own, a few average attempts to go solo and some quite successful ones using other people's designs and PCBs. They were satisfying to do, but didn't have the performance of good commercial amps and also took a long time, which I am short of at the moment. So that isn't the most tempting option, currently.
I suppose an other option would be to increase the budget and go for good/midrange nearly-new options. Doable but only with many days of (extra) overtime at work, so it would need to achieve quite substantial benefit.
In the past I've built my own, a few average attempts to go solo and some quite successful ones using other people's designs and PCBs. They were satisfying to do, but didn't have the performance of good commercial amps and also took a long time, which I am short of at the moment. So that isn't the most tempting option, currently.
I suppose an other option would be to increase the budget and go for good/midrange nearly-new options. Doable but only with many days of (extra) overtime at work, so it would need to achieve quite substantial benefit.
So what would be the total budget and how many amplifiers are you aiming at? Also - would these need to be of identical model or can they be different (tweeters do not need as much power as woofers)?
I'm intending to get two stereo amps. And yes, one reason for preferring stereo amps is so that different powers can be used for the different drivers. Though as well as a traditional 2-way tweeter/woofer combo, I'm also wanting them to power upper and mid in a 3-way and lastly a 2-way woofer-assisted-wideband arrangement (i.e. they need flexibility).
For the upper/wideband drivers, an amp of say 35w or more (into 8ohms) would be fine; I'd like a bit more but probably above 60w would start to seem excessive. The amp for the woofer/midbass would be quite a lot more powerful, due to wanting scope for DSP - if it has lots of dynamic headroom then 50W might do, but more would be preferred; essentially i'd like about 120W clean peaks for music. But nothing really OTT; they'll be stacked and I much prefer lower profile cases.
As for budget, finances are a bit tight but I don't want to arbitrarily set a value - since too cheap may be a false economy, whilst after a point one sees diminishing returns; part of why I posted, really. FWIW my baseline (with old but very good amps) is around £400 for the pair; after that it is about the benefits of spending more (which may be numerous). Just vaguely, things start to seem expensive by around £600, much more than that and I'd need to be very persuaded that it was worthwhile.
For the upper/wideband drivers, an amp of say 35w or more (into 8ohms) would be fine; I'd like a bit more but probably above 60w would start to seem excessive. The amp for the woofer/midbass would be quite a lot more powerful, due to wanting scope for DSP - if it has lots of dynamic headroom then 50W might do, but more would be preferred; essentially i'd like about 120W clean peaks for music. But nothing really OTT; they'll be stacked and I much prefer lower profile cases.
As for budget, finances are a bit tight but I don't want to arbitrarily set a value - since too cheap may be a false economy, whilst after a point one sees diminishing returns; part of why I posted, really. FWIW my baseline (with old but very good amps) is around £400 for the pair; after that it is about the benefits of spending more (which may be numerous). Just vaguely, things start to seem expensive by around £600, much more than that and I'd need to be very persuaded that it was worthwhile.
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45 quid buys me a 80W/ch Mosfet amp, with FM / USB / Bluetooth module, brand new.
Smaller outputs start about 9 GBP.
You can build from new, old parts and build quality can be issues, it seems B & O used cheap capacitors in their overly expensive sets.
Some had STKs, same as Kenwood sets priced at 20% of their prices...
Anyway, they have stopped making audio systems, as have many others.
I would prefer the classic Japanese sets , except Denon, Yamaha and Onkyo.
Much better in terms of materials used, and fairly simple circuits.
If you are not in a hurry, keep that in mind.
Oh, and check out Class D modules, the prices seem very low.
Smaller outputs start about 9 GBP.
You can build from new, old parts and build quality can be issues, it seems B & O used cheap capacitors in their overly expensive sets.
Some had STKs, same as Kenwood sets priced at 20% of their prices...
Anyway, they have stopped making audio systems, as have many others.
I would prefer the classic Japanese sets , except Denon, Yamaha and Onkyo.
Much better in terms of materials used, and fairly simple circuits.
If you are not in a hurry, keep that in mind.
Oh, and check out Class D modules, the prices seem very low.
For vintage amps, I suggested to start with products that were highly regards and popular. For exemple, the Hafler DH 200 and the Dynaco ST 70 have so much follower that it is very easy to repair or maintain.
OP is in UK, the makes mentioned above may not have sold as much as say NAD, Quad or Japanese.
That is another constraint, you have to consider what is available for sale, and at what price.
That is another constraint, you have to consider what is available for sale, and at what price.
One option that comes to mind are the Rotel RMB multi-channel power amplifiers. They seem to be available in 3, 5 and 6 channel versions - both used and also new ones. Taking the route of two 3-channel amplifiers would provide full channel separation (power transformer per channel) and option to upgrade to 3-way speakers.
Thanks, yes those might be possibilities. The ones i looked at reached a similar price to separate power amps, but they aren't so common; it might be just a case of waiting until they come up at the right price.
WRT the above: yes, some brands are/were popular in limited parts of the world, so are both hard to get and cost more here. A similar story for less common higher end models from any brand. But I'm not specifically wanting old classic or sought-after models, I'm simply after good (audio) specifications and build quality on a budget; used amps are just one possibility for saving money 'if' I could maintain them (hence the OP).
In fact as time goes on i'm starting to think of buying new (or nearly new) for the smaller amp and just going second-hand for the bigger one, which is where the bigger savings are needed.
WRT the above: yes, some brands are/were popular in limited parts of the world, so are both hard to get and cost more here. A similar story for less common higher end models from any brand. But I'm not specifically wanting old classic or sought-after models, I'm simply after good (audio) specifications and build quality on a budget; used amps are just one possibility for saving money 'if' I could maintain them (hence the OP).
In fact as time goes on i'm starting to think of buying new (or nearly new) for the smaller amp and just going second-hand for the bigger one, which is where the bigger savings are needed.
You must have selected a poor design to build or did something wrong in the build process. Most DIY amplifiers actually outperform commercial built offerings due to less constraints required for mass production. They do take up a lot of time though. Power supply and mechanical design are where a lot of DIY amps fall short.
Hmm, that is interesting @jwilhelm. If true then the DIY route is still a possibility, and would certainly address my concerns of build quality and maintainability. Though I'd be relying a lot on other people's designs, since I have insufficient skill of my own.
In fact, I already have the expensive components somewhere (big torroids, bigger heatsinks, mosfets, PCBs etc) for building a few of Rod Elliotts ESP P101 amps. As I understand it, these are designed to be approachable by the average DIYer rather than being the last word in complexity, but are supposed to still perform very well. Possibly with simplicity might come reduced risk of noise and hiss; a key requirement of mine, since for my intended use it would be much easier to hear than many other mild imperfections.
I'd have to seriously change my timescale for getting things up and running, but I have some old amps that would tide me over.
In the UK, leak tube amp enjoy a very good reputation. Also Mission Cyrus I and II are still highly regards. Radford is another name that came in mind.
I like roadworthy Class AB PA amps. Road dogs have tired electrolytic capacitors, dirty heat sinks, dodgy volume pots or input output connectors. All usually available. Fans may need to be replaced. I've found input resistors ($.002 ea) blown by some dingbat plugging a 75 watt guitar amp in the mike jack. I've had to replace my amp fleet, since the burglar carried off the music room set, the performance set, and the TV room set all in 9/20. I've donated some to churches. I've repaired Peavey 2 ea PV-4c, PV-1.3k, 2 ea CS800s, M-2600 (no fan or DC protection),3 ea MMA-875t ( mono mixer) 2 ea MMA-8150 (mono mixer) QSC CX300 (no volume knobs, screwdriver slots) . There was some availability problem of the J174 jfet for Peavey but they are back in production. CA3080 IC's are not available but are waay forward of the usual blowup areas, the output transistors, drivers, predrivers, and VI limiters. MMA-875/150 make sure you get an input board for RCA jacks, the screw terminal inputs only work on telephone circuits. MMA's have no fan but have to sit flat to cool.
Crown is generally repairable, although the ODEP circuit has a custom resistance network that doesn't usually fail, but if it does requires a kluge board of a dozen resistors. Crown has a MA-180 MA280 line for monaural use too. Stay away from Crown DC300, beautiful case and stellar reputation for 1970 but designed to produce DC on actuators which speakers do not tolerate. One DC adjust pot wiper disconnect can ruin a $200 bass driver.
So what wattage do you need? Different for bass & treble? Note many of the Peavey PA amps the fan runs slowly if the heat sink is cold, so not a problem if amp is behind a couch or record rack. The QSC fan was really noisy but it was designed for announcements in warehouses.
Note post #9, I have a dynaco ST70, which I've put about 20000 hours on. It was really nice sounding for 1961, pretty good for 1970 when I bought it, and totally outclassed by all the amps listed previously. 1% HD unless you change the driver board. The best triple 12ax7 driver board is out of production. My driver board is the original dynaco 7199 tube one, which tube is a total unicorn these days. The output tubes are 6CA7 (subst EL34), and of the 8 modern replacements I've bought, 7 were good. Note ST70 runs so hot electrolytic capacitor life is about 5000 hours. Ive had four sets in it since 1970, and don't run it because of this and the 300 w draw.
Crown is generally repairable, although the ODEP circuit has a custom resistance network that doesn't usually fail, but if it does requires a kluge board of a dozen resistors. Crown has a MA-180 MA280 line for monaural use too. Stay away from Crown DC300, beautiful case and stellar reputation for 1970 but designed to produce DC on actuators which speakers do not tolerate. One DC adjust pot wiper disconnect can ruin a $200 bass driver.
So what wattage do you need? Different for bass & treble? Note many of the Peavey PA amps the fan runs slowly if the heat sink is cold, so not a problem if amp is behind a couch or record rack. The QSC fan was really noisy but it was designed for announcements in warehouses.
Note post #9, I have a dynaco ST70, which I've put about 20000 hours on. It was really nice sounding for 1961, pretty good for 1970 when I bought it, and totally outclassed by all the amps listed previously. 1% HD unless you change the driver board. The best triple 12ax7 driver board is out of production. My driver board is the original dynaco 7199 tube one, which tube is a total unicorn these days. The output tubes are 6CA7 (subst EL34), and of the 8 modern replacements I've bought, 7 were good. Note ST70 runs so hot electrolytic capacitor life is about 5000 hours. Ive had four sets in it since 1970, and don't run it because of this and the 300 w draw.
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Thanks,
I'm not really into tubes so the Leak amp wouldn't be on my shortlist, but I remember how desirable the mission cyrus amps were. They look a bit strange IMO but had a great reputation here. There aren't large numbers around the second hand market, compared to some brands, but sufficient to find a decent one.
Yes, PA amps can be superb value for money, I have a Behringer A500 that was used for subwoofer duties, and I hear the newer A800 is much better still. I like that most have balanced inputs by default, as well. But unfortunately they aren't entirely suitable for my purpose here, being designed for massively more power than I could ever take advantage of rather than some of the subtleties that I would like for the application (such as extremely low noise).
I'm not really into tubes so the Leak amp wouldn't be on my shortlist, but I remember how desirable the mission cyrus amps were. They look a bit strange IMO but had a great reputation here. There aren't large numbers around the second hand market, compared to some brands, but sufficient to find a decent one.
Yes, PA amps can be superb value for money, I have a Behringer A500 that was used for subwoofer duties, and I hear the newer A800 is much better still. I like that most have balanced inputs by default, as well. But unfortunately they aren't entirely suitable for my purpose here, being designed for massively more power than I could ever take advantage of rather than some of the subtleties that I would like for the application (such as extremely low noise).
Behringer service manuals and schematics are copywrited, and not available. Period. Peavey Crown & QSC schematics are all over the internet. Peavey there is even a crossover list around of semiconductor in-house part numbers to industry part numbers.
MA-2600 is stereo 75 w/ch, MMA-875t is mono 75 w/ch (one pair output transistors) MA-180 is 80 w/ch. I've bought the MMA-875t as low as $20 each plus freight working, and the PV-4c with blown up outputs for the same price. A CS800s with blown input resistors was $100 and is the best sounding of the lot. In Europe people have repaired Swedish and HK PA mono warehouse amps they got for coins at a flea market or boot sale. The output transformer warehouse amps usually have provides cheap & totally reliable speaker protection, but rolls off below 50 hz.
I listen to classical music a lot at 1 Vav, or `1/8 watt. However volume peaks of 70 db can require 50 or 70 watts for a second or two. I do use 2 way speakers with a passive crossover which can produce 110 db or so at full volume in my music room.
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Having recently purchased a fine looking and sounding Quad 303 power amp (an itch that needed scratching) I would suggest that a couple of these would fit the bill at c.£250 to £350 each. They are sensitive (input wise), cool running, and still very well supported, e.g. AmpLabs, Dada Electronics, and even the UK based Quad service team, or DIY because all the documentation is available online. The sound is somewhere between my valve amp and my Hypex Ncore class D amp. Hope this helps.