Hi All,
I need some opinons from all you experts. I have a 1972 Beomaster 3000 system which is incredibly beautiful to look at but I think it's time to refit it. I've repaired numerous components over the years but I can't live with the intermittent faults, noise and drop outs it suffers from. Also, every time I change components, the traces break becuase they are corroded. It'd be easier to just get a new amp but I don't want this system to just sit unused.
I'm not sentimental about analog amps and I think the class D projects I've bult for boom boxes, garage amps etc. sound much better.
So what I want to do is refit it - keeping the FM/AM tuner board, which works fine, and replacing the preamp and power amps with class D. I also thought putting in a computer PSU could supply all the voltages it needs. I'm not an electronics expert but fairly skilled with a soldering iron and audio builds in general.
What are your opinions about the best pre-made boards to buy for the amp and pre-amp (I need a preamp for my turntable)? The power amp needs to be around 50 W (RMS) per channel for my purposes. I'd also fit a blutooth module. The boards need to have analog pots that I can rewire to the existing slider controls on the front panel (Vol, Bass, Treble).
Thanks!
Theo
I need some opinons from all you experts. I have a 1972 Beomaster 3000 system which is incredibly beautiful to look at but I think it's time to refit it. I've repaired numerous components over the years but I can't live with the intermittent faults, noise and drop outs it suffers from. Also, every time I change components, the traces break becuase they are corroded. It'd be easier to just get a new amp but I don't want this system to just sit unused.
I'm not sentimental about analog amps and I think the class D projects I've bult for boom boxes, garage amps etc. sound much better.
So what I want to do is refit it - keeping the FM/AM tuner board, which works fine, and replacing the preamp and power amps with class D. I also thought putting in a computer PSU could supply all the voltages it needs. I'm not an electronics expert but fairly skilled with a soldering iron and audio builds in general.
What are your opinions about the best pre-made boards to buy for the amp and pre-amp (I need a preamp for my turntable)? The power amp needs to be around 50 W (RMS) per channel for my purposes. I'd also fit a blutooth module. The boards need to have analog pots that I can rewire to the existing slider controls on the front panel (Vol, Bass, Treble).
Thanks!
Theo
Quite a while ago, an, at that time reputable German Audio Magazine, tested expensive Phono pre-amps. The clear winner was a high quality DIYS phono PCB, that was planted directly into the record player, connected to the magnet with the shortest wire possible. The raw-power supply (rectification and first buffer cap´s) was placed out of the player.
If you find some high grade phono pre, maybe from Pass Labs or else, this would be a very interesting option.
The amplified phono signal can be handled like any line source and is much less prone to beeing disturbed.
Maybe not an idea for anyone, but sure an interesting option.
If you find some high grade phono pre, maybe from Pass Labs or else, this would be a very interesting option.
The amplified phono signal can be handled like any line source and is much less prone to beeing disturbed.
Maybe not an idea for anyone, but sure an interesting option.
Hi, thanks for the advice. I had thought of putting the preamp in the turntable, I will see how It goes. I don't have a big budget so I ordered one of the Chinese little bears. I plan to keep its power supply separate now. The Beomaster amp runs off 32V I think, but I am not keeping the power supply.. it has a lot of hum, probably due to its age. I already changed the caps and rectifier on it, which blew a few years ago. I have a 20V laptop PSU that I will try out. Waiting for the preamp to arrive at the moment.
I picked up a Technics SA250 amp yesterday to use as a stop gap, but actually pretty impressed by it, although I think the bass is a bit 'flat'.
Theo
I picked up a Technics SA250 amp yesterday to use as a stop gap, but actually pretty impressed by it, although I think the bass is a bit 'flat'.
Theo
Since I tried some very cheap Alibaba / eBay SMPS boards, I´m cured of using these old laptop junk. You never know how it does with audio.
You get these in any voltage and they are remarkable silent.
Example:
DuoWeiSi 36V 250W 7A Switching Power Supply Board Audio Power Supply AC DC Isolated Power Module 220 to 36V-in 3D Printer Parts & Accessories from Computer & Office on Aliexpress.com | Alibaba Group
AC-DC 100V-265V Bis 36V 5A Schaltnetzteil Adapter Switching Power Supply SMPS K1 | eBay
You get these in any voltage and they are remarkable silent.
Example:
DuoWeiSi 36V 250W 7A Switching Power Supply Board Audio Power Supply AC DC Isolated Power Module 220 to 36V-in 3D Printer Parts & Accessories from Computer & Office on Aliexpress.com | Alibaba Group
AC-DC 100V-265V Bis 36V 5A Schaltnetzteil Adapter Switching Power Supply SMPS K1 | eBay
The ebay ones may "sound" better, but as for safety and EMC I would trust and old laptop-adapter much, much more.
Not saying that the ones you show are dangerous, just saying that its very hard to tell without proper (destructive) testing or analysis.
Kind regards TroelsM
What about these? Just as bad?
DC 5V-24V Universal Regulated Switching Power Supply 1A-60A 10W-480W LED 3D PSU | eBay
DC 5V-24V Universal Regulated Switching Power Supply 1A-60A 10W-480W LED 3D PSU | eBay
Sorry, but I don´t know. As I see it, it comes down to trust. Do you trust HP, Lenovo and their QA-dept. more than a ebay-seller?
Again: maybe the ebay-PSU's are perfectly fine, but how would you know?
I bought many parts from ebay, but never anything that connects to mains power.
TroelsM
Hi TroelsM, have you ever read the fine print on your holy brand brick?
HP or Lenovo buy their SMPS´s from some Chinese Manufacturer for less than a $ and put a label on it. These bricks sure meet the demands of a Laptop. Some work well with a D-amp, others not.
These cheap power modules linked here,from Ali or ebay, are produced in the millions. The design is proven, probably stolen from the US and works very well with D-amps. They have a lot more power than the usual laptop brick which ends at 90 watt.
The world has choosen to use medium-tech equipment from the yellow man for reasons of cost.
Sure some Danish high ender can ignore the fakt and be sentimental with brand names, but many here want the most for their money and look for proven low cost alternatives. Like the rest of the world. When the big manufacturers buy in China, why should I buy expensive? Just to waste money and in the end get the same China stuff, relabeled?
HP or Lenovo buy their SMPS´s from some Chinese Manufacturer for less than a $ and put a label on it. These bricks sure meet the demands of a Laptop. Some work well with a D-amp, others not.
These cheap power modules linked here,from Ali or ebay, are produced in the millions. The design is proven, probably stolen from the US and works very well with D-amps. They have a lot more power than the usual laptop brick which ends at 90 watt.
The world has choosen to use medium-tech equipment from the yellow man for reasons of cost.
Sure some Danish high ender can ignore the fakt and be sentimental with brand names, but many here want the most for their money and look for proven low cost alternatives. Like the rest of the world. When the big manufacturers buy in China, why should I buy expensive? Just to waste money and in the end get the same China stuff, relabeled?
@tallnutt
these you linked will work just the same. They are more refined, as you can adjust output with most of them, maybe +-5%. The metal case makes them safer to touch and keeps the EMI inside.
As the D-amp always radiates some kind of high frequency dirt, it should be put in a screening container (case) anyhow. So the finished amp will be protected from touching and radio emission. The naked modules are much smaller, so some will prefer them.
If you experiment a lot and use your DIYS amps open for quite some time, to test (no kids and animals!), you might be happier with such a SMPS in a case. DIYS is "decide it your self".
these you linked will work just the same. They are more refined, as you can adjust output with most of them, maybe +-5%. The metal case makes them safer to touch and keeps the EMI inside.
As the D-amp always radiates some kind of high frequency dirt, it should be put in a screening container (case) anyhow. So the finished amp will be protected from touching and radio emission. The naked modules are much smaller, so some will prefer them.
If you experiment a lot and use your DIYS amps open for quite some time, to test (no kids and animals!), you might be happier with such a SMPS in a case. DIYS is "decide it your self".
Are you refering to me?
. Yes I'm sentimental about the B&O stuff, but by no means high-end. I would prefer the low cost alternative anyday. If you look at my old posts youll see that I have done an active speaker with and old laptop-brick-psu. I used an ebay boost-regulator to get the voltage from 19V to 34V to fit the ebay classD. ( Btw: the boost-regulator was unstable and had to be modifed to work.)
El-cheapo active LOUDspeaker
High end...
Yes, most likely the mains-powered PSU's from ebay are perfectly fine, but you dont know.... - if Lenovo, Dell or HP made a PSU that were dangerous I think we would have heard about it.
Please note that I have expressed nothing about sound-quality or whether one PSU would work better than the other. I only talked about safety.
Its up to the individual DIY'er and please do as you like. - but mains voltage can and will kill you if you are having a bad day.
Kind regards TroelsM
Edit: My old trusted kitchen-radio for the last 15 years have been a Beomaster 3000. Works perfect and I love it, but if the amp failed beyond repair, I would consider classD from ebay.
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Did you ever try touching the mains line with your hand, while standing in a ditch on a concrete floor, with wet shoes? You learn the hard way that mains voltage is not good for your health and may be your last experience ever. Did this in a garage where the landlord had done the electricity by him self and accidentally exchanged the black and green/yellow wires in a connector. So earth was alive... which is what the Amazonas should be, but not the case of a lamp.
I honestly hope that anyone here has a degree in electric engineering, but that might not be the case with some. The EU is trying all it can do to prohibit building or repairing anyone from anything. Even today, practically you are not allowed to DIYS any electric device, car or any installation in a building. Even a single chassis passive loudspeaker has to be EMI tested, if you give it to your daughter or best friend.
I love posts where people are concerned about safety. In a few years we will be only allowed to buy Chinese appliances, with our hands tied behind our backs. Then, everything will be safe. Brave new world.
So the Beomaster has to be carefully taken to the recycling facility, not refited, you are right. That would be much more safe and create new work space in China.
I honestly hope that anyone here has a degree in electric engineering, but that might not be the case with some. The EU is trying all it can do to prohibit building or repairing anyone from anything. Even today, practically you are not allowed to DIYS any electric device, car or any installation in a building. Even a single chassis passive loudspeaker has to be EMI tested, if you give it to your daughter or best friend.
I love posts where people are concerned about safety. In a few years we will be only allowed to buy Chinese appliances, with our hands tied behind our backs. Then, everything will be safe. Brave new world.
So the Beomaster has to be carefully taken to the recycling facility, not refited, you are right. That would be much more safe and create new work space in China.
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