@ewildgoose,
Seems you are a convert. Are you using this room correction for 2 channel audio or for 5.1?
I'd love to do this as well, the high-end receivers all seem to have room correction these days.
Problem is, using PC, you need an extra A/D and D/A stage that has to sound very good - what audio card are you using?
For 2 channel I suppose it's possible to keep the first part in the digital domain (Cd digital out->PC dig in-) but can't be done for 5.1 I think?
Thanks for all your input ewildgoose!
Yves
Seems you are a convert. Are you using this room correction for 2 channel audio or for 5.1?
I'd love to do this as well, the high-end receivers all seem to have room correction these days.
Problem is, using PC, you need an extra A/D and D/A stage that has to sound very good - what audio card are you using?
For 2 channel I suppose it's possible to keep the first part in the digital domain (Cd digital out->PC dig in-) but can't be done for 5.1 I think?
Thanks for all your input ewildgoose!
Yves
Regarding the speaker ground lead: is it essential to attach this to the terminal on the UCD400 module instead of the normal practice of attaching it to the centre tap of the smoothing caps as on linear amps as I noticed 2 fine circuit traces coming off near the speaker out terminals; something to do with the feedback?
Is the practice of referencing the main circuitry to ground by using ground lift resistors at the input sockets,which gives superb hum free performance with my present AUDIO SYNTHESIS modules, acceptable with the UCD modules?
Curious,
Bob Lewis
Is the practice of referencing the main circuitry to ground by using ground lift resistors at the input sockets,which gives superb hum free performance with my present AUDIO SYNTHESIS modules, acceptable with the UCD modules?
Curious,
Bob Lewis
I asked this to Jan-Peter - I had found a DC protection circuit on the net, but it had a common ground.
Jan-Peter told me not to bring the grounds together because of the feed-back circuit.
He also told me not to connect the signal (input) ground together with the power ground, as it would degrade sound quality.
Jan-Peter told me not to bring the grounds together because of the feed-back circuit.
He also told me not to connect the signal (input) ground together with the power ground, as it would degrade sound quality.
I am using it for both 2 channel and 5.1. I do all my decoding on the PC. I use Mythtv (www.mythtv.org) as my media player and everything pops up on the TV or LCD control panel like a set top box. I get tv timeshifting, music, video, dvd, weather, games and more through this system.
The processing is done using filters in Brutefir. I only have 4 surround speakers and two subwoofers (a kind of 4.2 setup), so I use some stuff in brutefir to downmix the 5.1 signal. Bass is done simply by putting everything into stereo on the front speakers and then applying my favourite crossover to extract the bass (currently 120Hz with a steep filter). Bass speakers are very large 15" Tempests in an IB based setup.
As I said though. When you are shoving 5-10dB of correction into the system you are potentially going to see clipping with only a few watts of real signal. So you need a pretty decent amp which isn't going to show this until it really hits it's limit. The digital amps seem somewhat better at this than some analogue amps. In particular I have both Zappulse and UCD400 and both seem to work extremely well (versus my Meridian 557 power amp)
Ed
The processing is done using filters in Brutefir. I only have 4 surround speakers and two subwoofers (a kind of 4.2 setup), so I use some stuff in brutefir to downmix the 5.1 signal. Bass is done simply by putting everything into stereo on the front speakers and then applying my favourite crossover to extract the bass (currently 120Hz with a steep filter). Bass speakers are very large 15" Tempests in an IB based setup.
As I said though. When you are shoving 5-10dB of correction into the system you are potentially going to see clipping with only a few watts of real signal. So you need a pretty decent amp which isn't going to show this until it really hits it's limit. The digital amps seem somewhat better at this than some analogue amps. In particular I have both Zappulse and UCD400 and both seem to work extremely well (versus my Meridian 557 power amp)
Ed
Yep, I use it with a passive pre (as you can see if you read back about 9 messages!).
I have a cheapo maplins variable attenuator that I took apart to make a multichannel attenuator. Tracking is poor, but the end result sounds extremely decent. I also have an 8 way DACT pot which will be used later.
In my case I loose 6dB of gain due to my wiring setup, but still there is plenty of gain (for me). Basically work out what gain you need and ask Jan-Peter nicely and he will build it for you.
I doubt most people need anything other than a passive pre with CD output (which has pretty high output levels)
I have a cheapo maplins variable attenuator that I took apart to make a multichannel attenuator. Tracking is poor, but the end result sounds extremely decent. I also have an 8 way DACT pot which will be used later.
In my case I loose 6dB of gain due to my wiring setup, but still there is plenty of gain (for me). Basically work out what gain you need and ask Jan-Peter nicely and he will build it for you.
I doubt most people need anything other than a passive pre with CD output (which has pretty high output levels)
An externally hosted image should be here but it was not working when we last tested it.
is this a good setup, this will be just a temporary setup while i'm waiting for an electrician to install a 20A (115VAC) circuit in my room, i only have a single 15A (115VAC) circuit right now. then i'll install another 800VA transformer for a true dual mono power supply.
i didn't include fuses in the schematics just for simplicity and my schematic program doesn't have a transformer with dual secondary, that's why i just connected 2 single output transformer just to have a graphical diagram.
i want to know if this setup will work and doesn't have any danger due to the parallel connection of the two pairs of bridge rectifiers? or should i do this in a different way?
thanks for the help,
onixuser
Hi,
I've been thinking about this very thing recently.
I believe this is exactly what Bruno had in mind with respect to his previously discussed comment about not using dual rectifiers because it invites serious hum issues (a post which I've tripped over earlier today). Seems to make sense looking at it, the rectifiers wont' be identical..... etc.
So it wasn't really directed toward using the dual rectifier approach per se.
I think what you'd want to do here is to delete your second pair of rectifiers and caps, and just double the capacitance value to drive another channel with, or equivalently move the caps over to the other bank and just ditch the extra two rectifiers.
Best Regards,
Chris
I've been thinking about this very thing recently.
I believe this is exactly what Bruno had in mind with respect to his previously discussed comment about not using dual rectifiers because it invites serious hum issues (a post which I've tripped over earlier today). Seems to make sense looking at it, the rectifiers wont' be identical..... etc.
So it wasn't really directed toward using the dual rectifier approach per se.
I think what you'd want to do here is to delete your second pair of rectifiers and caps, and just double the capacitance value to drive another channel with, or equivalently move the caps over to the other bank and just ditch the extra two rectifiers.
Best Regards,
Chris
What was bruno actually saying:
A) Use a single rectifier bridge (4 diodes) into a single set of rails (and drive 2 UcD's)
or
B) use a dual rectifier bridge (8 diodes) into a single set of rails (and drive 2 UcD's)?
The drawing we've seen here is extreme, but I was thinking option A.
So Bruno thinks we shouldn't do this?
What is the right way then for stereo?
Single rectifier Bridge into a single set of rails?
A) Use a single rectifier bridge (4 diodes) into a single set of rails (and drive 2 UcD's)
or
B) use a dual rectifier bridge (8 diodes) into a single set of rails (and drive 2 UcD's)?
The drawing we've seen here is extreme, but I was thinking option A.
So Bruno thinks we shouldn't do this?
What is the right way then for stereo?
Single rectifier Bridge into a single set of rails?
He was saying not to use two rectifiers feeding two sets of caps like you see above (below?) for two channels, and either go dual mono (two transformers) or use a single rectifier, but that was in context to the question, so I don't believe it rules out the commonly seen and respected dual rectifier method.
So with that, my current interpretation would be that you can use dual rectifiers (4 diodes per secondary) as shown on both TNT audio PSU design pages or the other "Zero distortion" equivalent guide, but dont' use either a single or a dual rectifier config to drive a second set of rails off the same transformer like you see above or you'll likely wind up with some mean hum.
So with that, my current interpretation would be that you can use dual rectifiers (4 diodes per secondary) as shown on both TNT audio PSU design pages or the other "Zero distortion" equivalent guide, but dont' use either a single or a dual rectifier config to drive a second set of rails off the same transformer like you see above or you'll likely wind up with some mean hum.
No problem.
I felt I should post that since I'm the guilty party for having brought the dual rectifier method into question regarding Bruno's comment on insidious hum.
I spent awhile searching for the post in question at the time and just couldn't find it (could have taken weeks). I tripped over it today though so I realized the context of what was said, and with the schematic posted just now I thought it was a good time to correct myself.
I think I would also try the same, as far as we know there are only advantages and the one disadvantage is the cost of a few extra dollars which isn't a big deal.
Regards
I felt I should post that since I'm the guilty party for having brought the dual rectifier method into question regarding Bruno's comment on insidious hum.
I spent awhile searching for the post in question at the time and just couldn't find it (could have taken weeks). I tripped over it today though so I realized the context of what was said, and with the schematic posted just now I thought it was a good time to correct myself.
I think I would also try the same, as far as we know there are only advantages and the one disadvantage is the cost of a few extra dollars which isn't a big deal.
Regards
thanks for the help, what i'll do is just disconnect the second pair of BR and the caps bank, temporarily, the first 54400uF bank of caps shld be enough to drive (2) UcD400.
so if i understand this correctly just connect the (+), (-), (GND) of the (2) UcD module in parallel to the (+), (-), (GND) outputs of the powersupply?
onixuser
so if i understand this correctly just connect the (+), (-), (GND) of the (2) UcD module in parallel to the (+), (-), (GND) outputs of the powersupply?
onixuser
Hi,
Some distance between the modules is a very good thing though, so don't place them on top of each other just to keep the wires short. If you use a respectable gauge and make the runs as straight as possible (no spare wire all coiled up and shoved inside) you can place a module on either side of the case with the supply in between. The further you seperate the modules the better.
BTW I hadn't even realized the amount of capacitance you were going to use, you're right, just one of those banks is lots for two modules probably even for a couple of two ohm loads.
Cheers
Some distance between the modules is a very good thing though, so don't place them on top of each other just to keep the wires short. If you use a respectable gauge and make the runs as straight as possible (no spare wire all coiled up and shoved inside) you can place a module on either side of the case with the supply in between. The further you seperate the modules the better.
BTW I hadn't even realized the amount of capacitance you were going to use, you're right, just one of those banks is lots for two modules probably even for a couple of two ohm loads.
Cheers
Has anybody compared the sound of the two versions of the UcD400 (with and without the AD opamp)?
I'm planning to build a 6-channel amp and I would like to save some money if I could.
Is the sound improvement (because I assume that there are no other changes) worth the additional cost? Any suggestions?
I'm planning to build a 6-channel amp and I would like to save some money if I could.
Is the sound improvement (because I assume that there are no other changes) worth the additional cost? Any suggestions?
Yves, the price doesn't seem to be a valid indicator nowadays...
I don't want to start a major war on this, but the price/value ratio in Hi-Fi (and even more in Hi End) isall over the place: just think about the cables/inteconnects, capacitors, etc.
I just need some sound (no pun intended) advice over the sound of the UcD with or without the darn opamps...
I don't want to start a major war on this, but the price/value ratio in Hi-Fi (and even more in Hi End) isall over the place: just think about the cables/inteconnects, capacitors, etc.
I just need some sound (no pun intended) advice over the sound of the UcD with or without the darn opamps...
The price Vs quality has run away but in this case these aren't "trick" parts with a non magnetic carved maple wood IC case, they're simply op amps.
Why the leap in cost? Hell if I know but that's what they cost. The AD is the better op amp, but it is 20X more costly and not everyone will care for that, so the cheaper and still very high quality opa134 is used with an option to upgrade, how nice is that.
If you pay the extra dime, you _will_ have a better sound.
Why not compare the data sheets for the two of them and you should be able to spot why in one of the graphs.
I'd imagine the opa134 would still provide a very high quality sound or it wouldnt' be used, so don't think it will sound like garbage unless you go for the upgrade, but if you can afford it, go for the AD, unless you only plan on making a subwoofer out of it, then forget it.
Why the leap in cost? Hell if I know but that's what they cost. The AD is the better op amp, but it is 20X more costly and not everyone will care for that, so the cheaper and still very high quality opa134 is used with an option to upgrade, how nice is that.
If you pay the extra dime, you _will_ have a better sound.
Why not compare the data sheets for the two of them and you should be able to spot why in one of the graphs.
I'd imagine the opa134 would still provide a very high quality sound or it wouldnt' be used, so don't think it will sound like garbage unless you go for the upgrade, but if you can afford it, go for the AD, unless you only plan on making a subwoofer out of it, then forget it.