Well, you see, at least up until a few years ago, the "big boys" (ie. HP, Dell, Lenovo) got their laptop bricks OEM'd at one of a very short list of companies, like Delta, LiteOn, Astec etc. who are arguably at the top of their game in this particular field.
And yes, i would personally trust them infinitely more than some random no-name featherweight near-empty-box you get for 2$ brand new off Aliexpress or whatever. Which, in addition to being EMI hell, may well also be potential death-traps...
And while it's true that damn near everything is indeed made in China nowadays, it also depends WHOM it's made FOR - and thus, who and how well / stringently handles the quality control
How often have you heard of stock (ie. NOT aftermarket / 3rd party) laptop chargers catching fire, hmm? :roll: Not all that often, would be my guess.
And yes, i would personally trust them infinitely more than some random no-name featherweight near-empty-box you get for 2$ brand new off Aliexpress or whatever. Which, in addition to being EMI hell, may well also be potential death-traps...
And while it's true that damn near everything is indeed made in China nowadays, it also depends WHOM it's made FOR - and thus, who and how well / stringently handles the quality control
How often have you heard of stock (ie. NOT aftermarket / 3rd party) laptop chargers catching fire, hmm? :roll: Not all that often, would be my guess.
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Safety is always a subject! Please take not all of my post too serious.
The metal cased SMPS from China are safer to handle than the naked ones, but for newbies with electricity the laptop power brick is the safest alternative. I think we all agree on that.
Batteries like LiPo can be dangerous, because of very high current, which can easily melt metal.
The metal cased SMPS from China are safer to handle than the naked ones, but for newbies with electricity the laptop power brick is the safest alternative. I think we all agree on that.
Batteries like LiPo can be dangerous, because of very high current, which can easily melt metal.
@Khron
I see anything from China very critical, as they have not the slightest sense of responsibility for what they sell. If you come from a culture of product piracy, this is no wonder.
But maybe you buy one of these SMPS and have a look at the build quality. They are really worth a try, run cold and radiation seems to be normal, if you put them into a closed metal housing. This is the only way to use them responsible. The minimum distances, a usual problem with Chinese power supplies, are VDE standard.
Please consider how many of these are build, sure the ones we buy are only a fraction of the numbers which go for OEM use. It is something I would call professional quality, not death traps. Sometimes even a Chinese dealer can not make a part he sells worse than it is. Would be more expensive to build sub industry standard than just deliver what is made to agree with European rules. You are right, there are still Eastern 230V products around, no one should use, but not these.
Off course you have to know how to use them! But that is the same with a kitchen knife.
I see anything from China very critical, as they have not the slightest sense of responsibility for what they sell. If you come from a culture of product piracy, this is no wonder.
But maybe you buy one of these SMPS and have a look at the build quality. They are really worth a try, run cold and radiation seems to be normal, if you put them into a closed metal housing. This is the only way to use them responsible. The minimum distances, a usual problem with Chinese power supplies, are VDE standard.
Please consider how many of these are build, sure the ones we buy are only a fraction of the numbers which go for OEM use. It is something I would call professional quality, not death traps. Sometimes even a Chinese dealer can not make a part he sells worse than it is. Would be more expensive to build sub industry standard than just deliver what is made to agree with European rules. You are right, there are still Eastern 230V products around, no one should use, but not these.
Off course you have to know how to use them! But that is the same with a kitchen knife.
I got the little bear chinese preamp today.. works fine, no nouse that I can detect at medium volume.
Now I need to get a stereo amp with treble / bass controls (that I can wire to existing sliders). I was going to use my 2.1 board but have realised it gives no bass control. I could use a 2.1 or 4.1, but it must have a way to control bass and treble in the stereo channel with separate pots.
Anyone please have any ideas for <$100???
Thanks.
Now I need to get a stereo amp with treble / bass controls (that I can wire to existing sliders). I was going to use my 2.1 board but have realised it gives no bass control. I could use a 2.1 or 4.1, but it must have a way to control bass and treble in the stereo channel with separate pots.
Anyone please have any ideas for <$100???
Thanks.
Can´t you use the bass slider pot to adjust the .1 volume? Depends on the way you want to use it when it´s finished. 2.1 or 2.0?
I have a comparable project with an old Yamaha CA-V1 integrated amp.
https://www.hifiengine.com/images/model/yamaha_ca-v1.jpg
The amplifier will be a unity with new build 2-way speakers. In the end I will only use the passive input selector and the power switch from the old amp. It will drive each chassis with a single amp, so 4 channels. No electronics inside the "active" loudspeakers at all.
For x-over I found the DSP from 3e-audio in the version with 3 separate pots for bass tremble and volume. Maybe have a look, this could fit for you too.
I´m going to combine it with a motorized pot, which will give me on/off and volume control over a remote. I don´t need more (old man).
I will see how to match these parts...
Maybe use the DSP as a volume /tremble /bass control if this is an option for you. You can program at which frequency it will work, a huge advantage over a fixed version and even fix room related problems. No need to use all 4 outputs.
It has symmetrical outputs and you can easily convert any cheap D-amp for such an input. Just look for the two input capacitors each channel has, lift one leg of each and you are there, symmetrical in. I will use two TDA7498e modules, one per side, which sound very good, even unmodified, with two out of the box SMPS.
ADAU1701-2In4Out | 3e Audio
The quality of the DSP is very good and 4 times the value of the Sure DSP at least. 38US$ inc. P&P fast delivery, took about a week China-Germany.
The programming is not that comfortable as expensive DSP´s, but since the ADAU 1701 is used so much, there is help to be found anywhere. Need a 4$ programmer to make it complete.
I have a comparable project with an old Yamaha CA-V1 integrated amp.
https://www.hifiengine.com/images/model/yamaha_ca-v1.jpg
The amplifier will be a unity with new build 2-way speakers. In the end I will only use the passive input selector and the power switch from the old amp. It will drive each chassis with a single amp, so 4 channels. No electronics inside the "active" loudspeakers at all.
For x-over I found the DSP from 3e-audio in the version with 3 separate pots for bass tremble and volume. Maybe have a look, this could fit for you too.
I´m going to combine it with a motorized pot, which will give me on/off and volume control over a remote. I don´t need more (old man).
I will see how to match these parts...
Maybe use the DSP as a volume /tremble /bass control if this is an option for you. You can program at which frequency it will work, a huge advantage over a fixed version and even fix room related problems. No need to use all 4 outputs.
It has symmetrical outputs and you can easily convert any cheap D-amp for such an input. Just look for the two input capacitors each channel has, lift one leg of each and you are there, symmetrical in. I will use two TDA7498e modules, one per side, which sound very good, even unmodified, with two out of the box SMPS.
ADAU1701-2In4Out | 3e Audio
The quality of the DSP is very good and 4 times the value of the Sure DSP at least. 38US$ inc. P&P fast delivery, took about a week China-Germany.
The programming is not that comfortable as expensive DSP´s, but since the ADAU 1701 is used so much, there is help to be found anywhere. Need a 4$ programmer to make it complete.
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Thanks gor the info Turbowatch. I will not use the bass channel because I have powered stereo speakers that don't need it, so I need bass control on the stereo. I hadn't thought of a dsp, but I have no idea how to use symmetrical outputs. Do you have a link to the amps you used with that dsp?
The DSP´s
boards based on the ADAU1701 are usually programmed by a software called Sigma Studio. It is free, you can download it. No cost to try. Maybe do that and load one of the DSP files into it. So you can see how it works. You can use a ready made file, change the values or add elements. It´s graphical and for some might be very easy to use. Depends only on you, how you get along with it. The finished file is then loaded to the DSP via a small interface. Like using these three pots for volume ect.
You also can use it with the DSP connected, while listening, to use equalizers, x-over or whatever you want, to match to your loudspeakers. This would be a chain of "computer-interface-DSP-amp-loudspeaker". The input to the DSP comes from your pre-amp.
In your case, the 3e-audio DSP, which got the pot´s already in hardware, would simply be used as a tremble/ bass/ volume stage. You use only two in- and outputs. You can program it as you like once and leave it as it is without interface etc.
Maybe have a look at the internet pages, weather you could make friends with such a device. Sound is very good, you find this DSP chip in many expensive active speakers today.
In my opinion the only way to go today, since the price is so affordable. There is hardly any audio that does not profit from such a device, even the the simplest full range speaker can get rid of the passive correction and sound better.
boards based on the ADAU1701 are usually programmed by a software called Sigma Studio. It is free, you can download it. No cost to try. Maybe do that and load one of the DSP files into it. So you can see how it works. You can use a ready made file, change the values or add elements. It´s graphical and for some might be very easy to use. Depends only on you, how you get along with it. The finished file is then loaded to the DSP via a small interface. Like using these three pots for volume ect.
You also can use it with the DSP connected, while listening, to use equalizers, x-over or whatever you want, to match to your loudspeakers. This would be a chain of "computer-interface-DSP-amp-loudspeaker". The input to the DSP comes from your pre-amp.
In your case, the 3e-audio DSP, which got the pot´s already in hardware, would simply be used as a tremble/ bass/ volume stage. You use only two in- and outputs. You can program it as you like once and leave it as it is without interface etc.
Maybe have a look at the internet pages, weather you could make friends with such a device. Sound is very good, you find this DSP chip in many expensive active speakers today.
In my opinion the only way to go today, since the price is so affordable. There is hardly any audio that does not profit from such a device, even the the simplest full range speaker can get rid of the passive correction and sound better.
The amp:
Usually the cheap D-amp modules we use are finished with asymmetric inputs.
The chips hardly all have symmetrical input in native form.
On most modules you can access the "pure" input by tapping into the input caps, directly before the Chip, ignoring the other parts on the board. This will be an advantage in most cases, I think.
If you take, as an example, this board with the TDA7498e, you see 4 red caps in a row betwwen the RCA and volume pot. One side goes to the input circuit and the other one to the legs of the D-chip. You need the caps connected to the chip only. Just removing the caps and re-positioning them, gives you the input you need for the symmetric output of the 3e-audio DSP.
An advantage is the broken ground connection, preventing hum.
If you are still unsure which amp to use, the pictured board is really nice. Two points: 1. the fan did never start while using it, even at 34°C in summer.
2. be sure to get the "e" version, the quite similar looking 7498 is not made for the lower, usual 4 ohm loads, so it will not drive any speaker.
It sounds quite as nice as the TDA3116, but while, with larger speakers, the smaller one lacks some authority with bass, while the 7498e deliveres. Something like 10US$ more might not make a difference for most here.
Maybe go the most easy way and buy one of 3e´s amp, they are very good as far as I could read. Even more $...
Usually the cheap D-amp modules we use are finished with asymmetric inputs.
The chips hardly all have symmetrical input in native form.
On most modules you can access the "pure" input by tapping into the input caps, directly before the Chip, ignoring the other parts on the board. This will be an advantage in most cases, I think.
If you take, as an example, this board with the TDA7498e, you see 4 red caps in a row betwwen the RCA and volume pot. One side goes to the input circuit and the other one to the legs of the D-chip. You need the caps connected to the chip only. Just removing the caps and re-positioning them, gives you the input you need for the symmetric output of the 3e-audio DSP.
An advantage is the broken ground connection, preventing hum.
If you are still unsure which amp to use, the pictured board is really nice. Two points: 1. the fan did never start while using it, even at 34°C in summer.
2. be sure to get the "e" version, the quite similar looking 7498 is not made for the lower, usual 4 ohm loads, so it will not drive any speaker.
It sounds quite as nice as the TDA3116, but while, with larger speakers, the smaller one lacks some authority with bass, while the 7498e deliveres. Something like 10US$ more might not make a difference for most here.
Maybe go the most easy way and buy one of 3e´s amp, they are very good as far as I could read. Even more $...
Attachments
The amp in the above configuration is 100% dead silent. It is only a test build up. Use a cordless drill to do the wires like that. It is really important, as it keeps a lot of noise in the wire and away from the amp. Dont´s use left overs from the garbage can. For final installation I use simple house installation, solid copper wires, stripped of the outer insulation and drilled. It will stay the way you put it and has quite some serious diameter. Signal connections may be screened 2-pole wire with the screen only connected at one side (the sending device) or drilled, wire of smaller diameter, as well.
DSP
As you can see it is fresh from the box. I have to figure out if you can program any pot to act as signal source for the DSP. I hope so, as it is programmable
If not I have to do some serious modding to the remote.
This is DIYS: You plan, collect, try, learn and sincerely hope to finally find the time to put it all together...
Found this at Sure Adau 1701 external Potentiometer - Q&A - SigmaDSP Processors and SigmaStudio Development Tool - EngineerZone
You might get an idea how this DSP stuff works. As I wrote, you do not need to use it more than once...
As you can see it is fresh from the box. I have to figure out if you can program any pot to act as signal source for the DSP. I hope so, as it is programmable
If not I have to do some serious modding to the remote.
This is DIYS: You plan, collect, try, learn and sincerely hope to finally find the time to put it all together...
Found this at Sure Adau 1701 external Potentiometer - Q&A - SigmaDSP Processors and SigmaStudio Development Tool - EngineerZone
You might get an idea how this DSP stuff works. As I wrote, you do not need to use it more than once...
Attachments
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Thanks for the great explanation! That definitely looks like the setup for me. Just two more questions.. are the pots on the DSP single or dual gang? And what will you do about having a volume pot on the DSP and on the amp? Can the amp pot be set permanently so that only one controls the volume?
Hi,
here is a link for the 3e amp (the smallest available at time) TPA3251 2x140W 2Ch Class D Audio Amplifier | eBay US$70
Your question is a bit tricky. In theory you can do as you wrote, but this would degrade the sound quality.
See, if you play a CD, at the output you get full resolution audio and can control it analog. No problem. But here things are different: You take analog and convert it to digital, which is done best with full signal strength, just a little before clipping. If you lower volume, you take less steps on the digital ladder. So your analog stages should always run at full distortion free level, like 2 volt rms, to stay near to the 100dB dynamic of the analog to digital converter.
What you can do best:
Remove the volume pot from the new board and connect your pot (slider). This slider will in most cases be logarithmic, not linear.
I would, maybe, parallel both sliders or use the one in best condition. Now they control an AD converter, not the signal!
Then, you have to change the pot-block in the Sigma Studio software, so it accepts a table for the sliders values. Should have been done before by someone, maybe we find an example somewhere.
No problem to measure the slider.
As far as I have seen, you can cut the PCB with the pots in parts, which makes installation more convenient.
This digital level volume control has the huge advantage you do not loose resolution of the ADC which take your 2 volt signal to process it in digital form.
If you listen at low or moderate volume and control it analog before the signal enters the DSP, you only use a fraction of the converters steps which cover 100dB in the ADAU1701 input. This is important, as the DSP is not sampling at 196kHz, but conservative 44 or so, which is absolutely OK for CD audio quality and human ears. The sense of higher than 44kHz digital audio can be questioned, if the CD resolution it is used right.
(The more expensive 196kHz chips are only useful for professional application, where you constantly loose resolution while mixing recorded sounds for example. You can not hear 80kHz audio!)
OK, hope I got it right.
here is a link for the 3e amp (the smallest available at time) TPA3251 2x140W 2Ch Class D Audio Amplifier | eBay US$70
Your question is a bit tricky. In theory you can do as you wrote, but this would degrade the sound quality.
See, if you play a CD, at the output you get full resolution audio and can control it analog. No problem. But here things are different: You take analog and convert it to digital, which is done best with full signal strength, just a little before clipping. If you lower volume, you take less steps on the digital ladder. So your analog stages should always run at full distortion free level, like 2 volt rms, to stay near to the 100dB dynamic of the analog to digital converter.
What you can do best:
Remove the volume pot from the new board and connect your pot (slider). This slider will in most cases be logarithmic, not linear.
I would, maybe, parallel both sliders or use the one in best condition. Now they control an AD converter, not the signal!
Then, you have to change the pot-block in the Sigma Studio software, so it accepts a table for the sliders values. Should have been done before by someone, maybe we find an example somewhere.
No problem to measure the slider.
As far as I have seen, you can cut the PCB with the pots in parts, which makes installation more convenient.
This digital level volume control has the huge advantage you do not loose resolution of the ADC which take your 2 volt signal to process it in digital form.
If you listen at low or moderate volume and control it analog before the signal enters the DSP, you only use a fraction of the converters steps which cover 100dB in the ADAU1701 input. This is important, as the DSP is not sampling at 196kHz, but conservative 44 or so, which is absolutely OK for CD audio quality and human ears. The sense of higher than 44kHz digital audio can be questioned, if the CD resolution it is used right.
(The more expensive 196kHz chips are only useful for professional application, where you constantly loose resolution while mixing recorded sounds for example. You can not hear 80kHz audio!)
OK, hope I got it right.
I just figured out which Beomaster 3000 you got. Nice. If it is in good optical condition, this is a very interesting object to modernize. Design is by Jacob Jensen.
I do not know the internals, but the inputs can be adjusted trough holes in the bottom. This could be a very useful feature to match different sources to the digital level.
The B&O stuff I know was always made with clear to define sub modules. If this is the same with yours, you might be able to use the analog "line in" whith the balance stage and remove most of the rest. Add your pre amp and go digital from there. This way you should inklude the tuner as well. Think about shielding it in metal before it is to late, as it could pick up noise. The FM band is sensible for some harmonics of digital stuff and SMPS.
If you become more comfortable with the DSP software, you could use some of the switches the B&O has for their original functions, but in the digital domain, if they are not too complicated, as the CPU and memory of the DSP have limits.
As I wrote, I had my fingers in some old B&O stuff. As beautiful it was designed, as impossible to repair where these beauties after ages in damp basements. The B&O service in Germany was not willing or able to repair them, as we found out on some occasions. Schematics? Impossible, top secret.
So, for many years, you could find them at the monthly garbage collection, together with old sofas in the better parts of my home town.
I think it is a sacrilege not to modern-digiti-lize it.
PS the 3e-audio amp that goes with the DSP for most is the best high end D-amp chip at time.
I do not know the internals, but the inputs can be adjusted trough holes in the bottom. This could be a very useful feature to match different sources to the digital level.
The B&O stuff I know was always made with clear to define sub modules. If this is the same with yours, you might be able to use the analog "line in" whith the balance stage and remove most of the rest. Add your pre amp and go digital from there. This way you should inklude the tuner as well. Think about shielding it in metal before it is to late, as it could pick up noise. The FM band is sensible for some harmonics of digital stuff and SMPS.
If you become more comfortable with the DSP software, you could use some of the switches the B&O has for their original functions, but in the digital domain, if they are not too complicated, as the CPU and memory of the DSP have limits.
As I wrote, I had my fingers in some old B&O stuff. As beautiful it was designed, as impossible to repair where these beauties after ages in damp basements. The B&O service in Germany was not willing or able to repair them, as we found out on some occasions. Schematics? Impossible, top secret.
So, for many years, you could find them at the monthly garbage collection, together with old sofas in the better parts of my home town.
I think it is a sacrilege not to modern-digiti-lize it.
PS the 3e-audio amp that goes with the DSP for most is the best high end D-amp chip at time.
Just read your post again: The little Bear is a phono pre amp, so it has to be integrated between RCA input and source selector, but best would be in the turntable, away from all high frequency stuff. The MM signals are very weak, MC even weaker.
Maybe you can go from the selector to the balance pot and then into the DSP, but it could be better to have a buffer stage in front of the balance. Maybe post some picture of the internals of the Beo? Such a buffer stage is nothing complicated or expensive, just a small PCB, but it needs clean PS.
Maybe you can go from the selector to the balance pot and then into the DSP, but it could be better to have a buffer stage in front of the balance. Maybe post some picture of the internals of the Beo? Such a buffer stage is nothing complicated or expensive, just a small PCB, but it needs clean PS.
I have a buddy that did that on his table — a jFET heas amp right at the headshell.
dave
There are quite some uncommon options with record players.
Many years ago I had a symmetric MM-pre, as the signal of the cartridge is symmetric in the beginning, eliminating any ground problems. Then the amplified signal left the player with line level, asymmetric as the rest ot the chain.
The pre-amp PCB was just under the tone arm base and the tiny wires went directly into the first stage of it. Worked well for years until I gave the phono away.
I never understood why this concept was not used commercially. Any professional microphone with XLR shows how to do it right. Most probably, when the industry moved from cristal pick up´s to moving magnet, someone decided to put the pre outside, to make the player universal and that was left as is was.
Even as it is none sens to sent this millivolt, micro ampere signal un-amplified through a asymmetric cable, where the screen is also one pole of the connection. Even more stupid to do this with MC signals, that are even weaker.
If you think about it, it is quite amazing how well such a technically imperfect system can sound.
If you have to add a phono-pre-amp to the system anyway, there is the option to do it better in DIYS Hifi and at least move the phono module where it belongs, into the player. Just keep the transformer out of the player, as it might induce noise into the chassis.
To build the first amp stage into the head shell is taking the idea even further, like a electret microphone capsule. Should work well with tone arms on the heavier side. Usually there should be enough room for two small FET´s and maybe an additional wire for the voltage feed if you think about it.
As most of the HIFI business has always been about easy money for the industry through a mass market, they sold what was produced cheapest, not what was best. Anyone who opens up average, commercial HIFI of the pre CD age today, will be amazed how such cheap junk could be sold to the masses so expensive, since PCB boards could be made mostly automated. Only very few manufacturers cared for what was inside. As long as it sold, the less was the better.
I myself, as a juvenile did not build amps by my own because i could, but because really high quality was so expensive at that time. Commercial amps of the 80´s where weak or sounded awful.
The technical optimum was left to the small high end sector and most of it moved to CD at a point when the record disk and pick up´s where about to reach their highest evolution stage. So no one thought about innovations for a dying system.
Many years ago I had a symmetric MM-pre, as the signal of the cartridge is symmetric in the beginning, eliminating any ground problems. Then the amplified signal left the player with line level, asymmetric as the rest ot the chain.
The pre-amp PCB was just under the tone arm base and the tiny wires went directly into the first stage of it. Worked well for years until I gave the phono away.
I never understood why this concept was not used commercially. Any professional microphone with XLR shows how to do it right. Most probably, when the industry moved from cristal pick up´s to moving magnet, someone decided to put the pre outside, to make the player universal and that was left as is was.
Even as it is none sens to sent this millivolt, micro ampere signal un-amplified through a asymmetric cable, where the screen is also one pole of the connection. Even more stupid to do this with MC signals, that are even weaker.
If you think about it, it is quite amazing how well such a technically imperfect system can sound.
If you have to add a phono-pre-amp to the system anyway, there is the option to do it better in DIYS Hifi and at least move the phono module where it belongs, into the player. Just keep the transformer out of the player, as it might induce noise into the chassis.
To build the first amp stage into the head shell is taking the idea even further, like a electret microphone capsule. Should work well with tone arms on the heavier side. Usually there should be enough room for two small FET´s and maybe an additional wire for the voltage feed if you think about it.
As most of the HIFI business has always been about easy money for the industry through a mass market, they sold what was produced cheapest, not what was best. Anyone who opens up average, commercial HIFI of the pre CD age today, will be amazed how such cheap junk could be sold to the masses so expensive, since PCB boards could be made mostly automated. Only very few manufacturers cared for what was inside. As long as it sold, the less was the better.
I myself, as a juvenile did not build amps by my own because i could, but because really high quality was so expensive at that time. Commercial amps of the 80´s where weak or sounded awful.
The technical optimum was left to the small high end sector and most of it moved to CD at a point when the record disk and pick up´s where about to reach their highest evolution stage. So no one thought about innovations for a dying system.
Thanks Turbowatch. The preamp module in the B&O was noisy and had distortion problems.. probably the transistors... But the radio section is good and I have worked out how to power it, so I am keeping that in (there was a full schematic in an envelope taped inside the case). The little bear makes no noise, even inside the B&O so I will keep it in there, inside its metal case. I was thinking of adapting some of the switches and the DSP will give a lot of options.. so all the switches will work.
I'm not sure I understand your answer to the pot question.. The power amp pot wil be replaced by my volume slider? But I don't understand what to do with the DSP volume pot.
Thanks.
I'm not sure I understand your answer to the pot question.. The power amp pot wil be replaced by my volume slider? But I don't understand what to do with the DSP volume pot.
Thanks.
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