I was wondering another thing about class-D modules.
For volume control, we're attenuating the input signal.
But since the transistors in the power output always pulse at full-on, full-off, wouldn't it be possible to decrease or increase this voltage in order to control volume?
That way, volume would be totally disconnected from the input signal?
Yves
For volume control, we're attenuating the input signal.
But since the transistors in the power output always pulse at full-on, full-off, wouldn't it be possible to decrease or increase this voltage in order to control volume?
That way, volume would be totally disconnected from the input signal?
Yves
Hi,
I think a better option would be either gut it totally and use it for parts. This way you don't have any unknown/mystery circuitry to contend with like that dual rectifier jobby you posted earlier, which I can't begin to understand either.
Or, sell it and put that money towards better parts where all parameters are better known. Does it have a toroid for the PSU? What's the regulation factor, or VA, it's likely to be on the poor side being an OEM amp.
Give your modules half a chance at working properly, if you should screw up with your method you're not only out an amp but a few modules as well.
It is very likely your own home built supply would be far better than that amp uses, if you do your homework on it. In the end you'll have more options to build on it with, or at least tweaking to find that perfect sound will be far simpler, as well as troubleshooting in general.
Also the amps were said to sound better operating from a voltage closer to their rated spec, if you're not worried about power you can easily use UCD180's as well.
It wouldn't hurt a single bit to use a bigger transformer if you want to power multiple modules off one transformer. How clean do you want it to play at higher power output?
The ideal rectifiers are probably HEXFRED based, for their ultra fast and soft recovery characteristics. It has been said you dont' need additional bypass caps with them, due to their soft recovery, most use them with it anyway, I would do the same. They are very expensive though.
Within these forums you'll find all the information you need to do the job right.
See chrisb03's posts here for an excellent example of a no compromise implementation. Cost is of course the limiting factor, you can at least decide on what areas the pennies will get pinched, and possibly leave options open to upgrade later on.
Please note, so far everyone who's replied has advised against doing it the way you've mentioned, don't be too quick to dismiss this advice.
Good luck.
Chris
I think a better option would be either gut it totally and use it for parts. This way you don't have any unknown/mystery circuitry to contend with like that dual rectifier jobby you posted earlier, which I can't begin to understand either.
Or, sell it and put that money towards better parts where all parameters are better known. Does it have a toroid for the PSU? What's the regulation factor, or VA, it's likely to be on the poor side being an OEM amp.
Give your modules half a chance at working properly, if you should screw up with your method you're not only out an amp but a few modules as well.
It is very likely your own home built supply would be far better than that amp uses, if you do your homework on it. In the end you'll have more options to build on it with, or at least tweaking to find that perfect sound will be far simpler, as well as troubleshooting in general.
Also the amps were said to sound better operating from a voltage closer to their rated spec, if you're not worried about power you can easily use UCD180's as well.
It wouldn't hurt a single bit to use a bigger transformer if you want to power multiple modules off one transformer. How clean do you want it to play at higher power output?
The ideal rectifiers are probably HEXFRED based, for their ultra fast and soft recovery characteristics. It has been said you dont' need additional bypass caps with them, due to their soft recovery, most use them with it anyway, I would do the same. They are very expensive though.
Within these forums you'll find all the information you need to do the job right.
See chrisb03's posts here for an excellent example of a no compromise implementation. Cost is of course the limiting factor, you can at least decide on what areas the pennies will get pinched, and possibly leave options open to upgrade later on.
Please note, so far everyone who's replied has advised against doing it the way you've mentioned, don't be too quick to dismiss this advice.
Good luck.
Chris
Yves Smolders said:
I believe it's possibly with some types of class-d amps, like open loop non feedback types, but it isn't with this one! I dont think that's easily done (efficiently) unless you're using some sort of switching supply anyway, which isn't the optimal or easiest way of doing things.
Regards
Thanks classd4sure,
I'm not dismissing any input - I wouldn't be posting here if I didn't appreciate the feedback...
Oh, admins, if i'm going off-topic here, please slap my wrists 😀
I'm not going to trash the A2 because it was one model under the flagship at the time, and I couldn't possibly replace it at the moment.
So I'll probably have a go at an external 2 channel UcD amp, it'll cost me a bit in parts, but a healthy 2*200W amp costs 1000 euro's at a minimum anyway (a Rotel for example), it'll be cheaper in DIY, AND I'll have that nice "I built this" feeling as I listen to my improved stereo
I'm not going to compromise on the amp, even when I don't go to ear-bleeding levels, there's the psychological effect of having a near-perfect amp, you just *know* it's not breaking a sweat.
So I'll probably go overkill on the toroidals, use the HEXFREDs as you mentioned and find some super quality caps. That I can handle; the soft-start circuit is tricky for a layman...
Thanks for the input!!
I'm not dismissing any input - I wouldn't be posting here if I didn't appreciate the feedback...
Oh, admins, if i'm going off-topic here, please slap my wrists 😀
I'm not going to trash the A2 because it was one model under the flagship at the time, and I couldn't possibly replace it at the moment.
So I'll probably have a go at an external 2 channel UcD amp, it'll cost me a bit in parts, but a healthy 2*200W amp costs 1000 euro's at a minimum anyway (a Rotel for example), it'll be cheaper in DIY, AND I'll have that nice "I built this" feeling as I listen to my improved stereo
I'm not going to compromise on the amp, even when I don't go to ear-bleeding levels, there's the psychological effect of having a near-perfect amp, you just *know* it's not breaking a sweat.
So I'll probably go overkill on the toroidals, use the HEXFREDs as you mentioned and find some super quality caps. That I can handle; the soft-start circuit is tricky for a layman...
Thanks for the input!!
I was worried you might be like me where all warnings against would push you to do it more 😀
Sounds like a great plan now. I understand the point about the soft start circuit, but you have some options available to you there as well.
Start here:
http://www.diyaudio.com/forums/showthread.php?threadid=44515
You might not want to use HEXFRED's once you see the price of them, regular cheapies should work great as well, properly bypassed like you'd be doing anyway. The real nice thing about the cheapies is that you can fasten them down to the chassis and dont' need to make a PCB for them! Once again be sure to see chrisb03's amp 🙂
Cheers
It looks great too. Very nice.
About the new inductor, does the fact that it's a ribbon play any part in lowering emissions? I ask because I was surprised to see it isn't fully encased as the previous one was. Certainly the extra cooling will be a help.
Thanks.
About the new inductor, does the fact that it's a ribbon play any part in lowering emissions? I ask because I was surprised to see it isn't fully encased as the previous one was. Certainly the extra cooling will be a help.
Thanks.
Shouls I worry about this? Found in the document posted by Jan-Peter in the 180 thread:
I sure wouldn't like to see N804's go up in flames!
How to add DC protection?
I sure wouldn't like to see N804's go up in flames!
How to add DC protection?
Yves Smolders said:Shouls I worry about this? Found in the document posted by Jan-Peter in the 180 thread:
I sure wouldn't like to see N804's go up in flames!
How to add DC protection?
Well, ...... probably only the woofer would burn out, but I guess that is bad enough 🙂
It would indeed be nice if there would be some of the shelf DC protection. I don't want to put a relay in between speaker and amp. Somewhere in one of the UcD threads, I think Jan-Peter or Bruno suggested to put a relay in the powerlines just before the UcD module to cut off the power to the module in case of a DC failure. So we need a circuit that detects DC and drives a relay when it detects DC to shut off the power to the module. Is there something available on the market that does this for lazy DIYers that don't want to develop it themselves? I plan not realy to use it since I only have the amps on when I listen to them, so if something is wrong I'll notice. My speakers are DIY so replacing a burned out driver would not be so expensive as having a N804 repaired.
Regards
Gertjan
noises
Hi,
When I turn on my UcD400's after I turn on everything else, there is almost no sound. When I leave it on and turn off and on the prepro (Linn 5103), there is a lot more noise (clicks). Is this normal?
Frans
Hi,
When I turn on my UcD400's after I turn on everything else, there is almost no sound. When I leave it on and turn off and on the prepro (Linn 5103), there is a lot more noise (clicks). Is this normal?
Frans
I've seen recommendations to use fast blow fuses inline with expensive speakers... OK they might blow on loud passages but no killer DC will ever reach them?
I have desinged a fast, sensitive DC protection in addtion to power on delay. This design is incorporated in the QRO pcb and is not a stand-alone unit.
I have been thinking of making this as a single pcb. Anybody interested?
The idea is 4th order Tjebushev filter at 7 Hz, fullwave rectification (simlified version) and DC level at 1.6 volts. Used opamps LM324 or similar. Output is "open collector" for driving speaker relay.
This protection was made for a 180/300 watt power amp.
I have been thinking of making this as a single pcb. Anybody interested?
The idea is 4th order Tjebushev filter at 7 Hz, fullwave rectification (simlified version) and DC level at 1.6 volts. Used opamps LM324 or similar. Output is "open collector" for driving speaker relay.
This protection was made for a 180/300 watt power amp.
Hi
Fast blows, hmmm, I use 3 amp slow blows in mine. They degrade from constant heating/cooling cycles and oxidize, become resistive, basically if you drive it hard sound quality takes a mean dive. Solution, replace often if driven hard, ... use bigger fuses yet. Then again if you size them to protect against a DC short like that of a blown output stage they'd probably last alot longer without degrading. I think mine are kind of sized as clipping detectors, they came with 2amp fast blows? It is alot easier and cheaper than trying to do it with relays though. Yeah, a beefy fast blow makes more sense.
Cheers
Fast blows, hmmm, I use 3 amp slow blows in mine. They degrade from constant heating/cooling cycles and oxidize, become resistive, basically if you drive it hard sound quality takes a mean dive. Solution, replace often if driven hard, ... use bigger fuses yet. Then again if you size them to protect against a DC short like that of a blown output stage they'd probably last alot longer without degrading. I think mine are kind of sized as clipping detectors, they came with 2amp fast blows? It is alot easier and cheaper than trying to do it with relays though. Yeah, a beefy fast blow makes more sense.
Cheers
To my knowledge from these forums, not from proper use, they are well designed, but hey, freak things happen. It's entirely up to you, I'm not sure if anyone has actually employed DC protection with them or not. OEM guys likely do though.
If you don't give them passive cooling by bolting them to a nice fat aluminum plate, the mosfets will overheat and fry. The case also needs to be well vented, no fans required though.
Regards
If you don't give them passive cooling by bolting them to a nice fat aluminum plate, the mosfets will overheat and fry. The case also needs to be well vented, no fans required though.
Regards
I knew this shouldn't have been my first DIY project 🙄
Those large toroidals and caps thingies I can handle, but those little tiny things on PCB's...
Oh well, I ordered 2 UcD400's so I'll just *have* to build them!
My worries are that this circuit could influence channel separation - could this happen?
Those large toroidals and caps thingies I can handle, but those little tiny things on PCB's...
Oh well, I ordered 2 UcD400's so I'll just *have* to build them!
My worries are that this circuit could influence channel separation - could this happen?
Re: noises
Hello Frans,
The problem is not with the UcD but with the Linn I guess. When the UcDs are on and you turn on/off the preamp, the preamp outputs probably produce some clicks or some DC at the output that will be just amplified by the UcD 400. The UcD modules themself behave extremely well when turning the on and off.
Best regards
Gertjan
FransDHT said:
Hello Frans,
The problem is not with the UcD but with the Linn I guess. When the UcDs are on and you turn on/off the preamp, the preamp outputs probably produce some clicks or some DC at the output that will be just amplified by the UcD 400. The UcD modules themself behave extremely well when turning the on and off.
Best regards
Gertjan
Re: Re: noises
Hi,
I was thinking the same. I'd think other amps with similar input stages are likely to amplify this signal as well. That's a quick and easy test you can try to help ease your mind.
Maybe you can work out a way to control the module via some sort of remote line from the pre amp?
Regards
ghemink said:
Hi,
I was thinking the same. I'd think other amps with similar input stages are likely to amplify this signal as well. That's a quick and easy test you can try to help ease your mind.
Maybe you can work out a way to control the module via some sort of remote line from the pre amp?
Regards