Please Help!
I want to build a seven channel UCD 400 but it is my understanding that you can only use the Hypex HG power supply for stereo use
so what is the best solution? I was thinking of making two four channel amps using four ucd400 modules with two power supplies and transformers i was thinking of basically making 2 dual stereo amps, do you think this will work?
I want to build a seven channel UCD 400 but it is my understanding that you can only use the Hypex HG power supply for stereo use
so what is the best solution? I was thinking of making two four channel amps using four ucd400 modules with two power supplies and transformers i was thinking of basically making 2 dual stereo amps, do you think this will work?
You can power as many modules as you like from a single powersupply. However, if you are intending to drive the thing hard and want better quality then as with all things the more powersupply you give it the better it will sound...
It would be perfectly possible to build a beefy single supply to power all your channels. Or you could build three power supplies (one front left, one front right and one for the rest) for a fairly high quality design with lower quality on th surround
Good luck
Ed W
It would be perfectly possible to build a beefy single supply to power all your channels. Or you could build three power supplies (one front left, one front right and one for the rest) for a fairly high quality design with lower quality on th surround
Good luck
Ed W
Dact is quite expensive.
I don't need motorized volume control - I'll have a nice receiver for normal operations (surround, easy listening) and will go with the passive volume coupled to the (modified?) DVD player for pure stereo. That's fixing the volume, sitting down and enjoy high end sound
So no different boxes, it'll only add to the complexity and adding cables/cable length - I guess there won't be too much noise from UcD's and the PS - I have them in a test setup now, an open case, with really bad signal cables (even bare wire parts in the signal wire) and it sounds sweeter than ever.
If it fails, I can still go with a seperate case
I don't need motorized volume control - I'll have a nice receiver for normal operations (surround, easy listening) and will go with the passive volume coupled to the (modified?) DVD player for pure stereo. That's fixing the volume, sitting down and enjoy high end sound
So no different boxes, it'll only add to the complexity and adding cables/cable length - I guess there won't be too much noise from UcD's and the PS - I have them in a test setup now, an open case, with really bad signal cables (even bare wire parts in the signal wire) and it sounds sweeter than ever.
If it fails, I can still go with a seperate case
@Carlos:
You'll need one PS per 2 channels I'm afraid - the DC detection circuit is for 2 modules only. You could of course get 3, and hook up the centre channel to the 2 side surrounds or back surrounds - you won't have DC control on that channel, but PS-wise it would work - surrounds don't go heavy on the available juice, but the centre channel does in surround mode. If its all 8 ohms, low power, don't worry about it. 40.000uF on tap is more than your regular 7.1 receiver has for all channels (Pioneer Elite for example, 2x 15.000uF for all channels, and that's class B!)
I'd even use standard PS for everything except the stereo channels.
Your stereo won't be affected by it.
So I recommend 2x stereo and 1x3 channel, using 3 toroids and 3 PS. Just don't use DC protection for centre channel, or add velleman K4701 B for the centre (passive DC protection, might fail, but something is better than nothing) - I hope I got the velleman model right. Use stereo for L & R, the second stereo for LS and RS, and the 3 channel for back surrounds and centre.
Even more pricedropping: If your surrounds and centre are "small" devices on your receiver/pre, and they are 8 ohms, you might get along with UcD180's, or use UcD400's on surround/centre with smaller toroids. Oversize for stereo just to feel good! - Bruno & JP claim 500VA per 2 channels will rock your world, certainly for 8 ohm speakers.
Alternative: you might consider using an extra PS (the low cost one) for the centre (if it's a small speaker, with 80hz high pass, it won't need too much power anyway) - I think it's overkill though.
You'll need one PS per 2 channels I'm afraid - the DC detection circuit is for 2 modules only. You could of course get 3, and hook up the centre channel to the 2 side surrounds or back surrounds - you won't have DC control on that channel, but PS-wise it would work - surrounds don't go heavy on the available juice, but the centre channel does in surround mode. If its all 8 ohms, low power, don't worry about it. 40.000uF on tap is more than your regular 7.1 receiver has for all channels (Pioneer Elite for example, 2x 15.000uF for all channels, and that's class B!)
I'd even use standard PS for everything except the stereo channels.
Your stereo won't be affected by it.
So I recommend 2x stereo and 1x3 channel, using 3 toroids and 3 PS. Just don't use DC protection for centre channel, or add velleman K4701 B for the centre (passive DC protection, might fail, but something is better than nothing) - I hope I got the velleman model right. Use stereo for L & R, the second stereo for LS and RS, and the 3 channel for back surrounds and centre.
Even more pricedropping: If your surrounds and centre are "small" devices on your receiver/pre, and they are 8 ohms, you might get along with UcD180's, or use UcD400's on surround/centre with smaller toroids. Oversize for stereo just to feel good!
- Bruno & JP claim 500VA per 2 channels will rock your world, certainly for 8 ohm speakers. Alternative: you might consider using an extra PS (the low cost one) for the centre (if it's a small speaker, with 80hz high pass, it won't need too much power anyway) - I think it's overkill though.
This Forum Rocks!!!!!!
I have never had so many responses so fast, Thank you!
Here is what i am going to do 3 toroids as recommended 2 power supply hg's from hypex and 1 standard supply for the center channel (center is already set to 80 hz) so as per Yves post I should be alright. any recommendations on the right size toroid's for this configuration. Also thank you all for your input
Cheers, Carlos
I have never had so many responses so fast, Thank you!
Here is what i am going to do 3 toroids as recommended 2 power supply hg's from hypex and 1 standard supply for the center channel (center is already set to 80 hz) so as per Yves post I should be alright. any recommendations on the right size toroid's for this configuration. Also thank you all for your input
Cheers, Carlos
Carlos,
3x500VA should be enough.
I'd take 800VA for the L&R stereo, 500VA for LS and RS, and finally 500VA for the 2 back surround channels plus centre.
Take 40v secondaries if you power lines are flaky (overvoltage on the grid) or 42v for maximum performance!
You might get away with smaller toroids than 500VA, but only if you won't push it to the max - the price difference below 500VA is only small. Above 650VA price (and size) seems to rise quite rapidly
Don't forget softstarts!
Yves
3x500VA should be enough.
I'd take 800VA for the L&R stereo, 500VA for LS and RS, and finally 500VA for the 2 back surround channels plus centre.
Take 40v secondaries if you power lines are flaky (overvoltage on the grid) or 42v for maximum performance!
You might get away with smaller toroids than 500VA, but only if you won't push it to the max - the price difference below 500VA is only small. Above 650VA price (and size) seems to rise quite rapidly
Don't forget softstarts!
Yves
A question of volume
Yves,
Yes the DACT is expensive. I have been using it as there was not a worthy competitor. Now with the availability of the inexpensive ladder types this will change, unless they are just too big to fit. Sound quality should not be a problem as the signal only passes through a single Dale resistor in getting to the output.
I would recommend the 10k version as your DVD player will not have any trouble driving it and less resistance in line with the signal is always good if what is driving it does’t care. To keep noise pick up low the control should be mounted in the amp box and connected with twisted shielded cable. The output of the volume control is much higher impedance than the signal source so much more prone to noise pick up. If you are using bare separate wires you should at least twist them together in +/- signal pairs and keep them away from other wiring that carries high current. Twisting the leads together will cause induced noise to enter both wires almost identically therefore mostly canceling out.
As for noise pickup it is usually in two forms, electrostatic or electromagnetic. (The third way is with a direct connection, don’t overlook this!) This translates to either capacitive coupled or transformer coupled. With lower input impedance, as with a 10k volume control, the capacitive coupled noise sees a heavier load so will induce less voltage. Conversely, the transformer induced noise will enter a higher signal current so will be a lesser percentage. With the 10k control the signal current will be 5-10 times higher so the induced noise will be that much smaller in proportion. This is a very significant reduction and is worth while!
If the noise is high frequency the only effective means to reduce it are distance and shielding. Shielding can be in the form of ferrite beads on the wire pairs. This actually builds a transformer of a single turn with each wire causing equal canceling currents to be formed. There has been more than one design saved with a single ferrite bead.
Hope this helps your understanding of what is going on with this very simple volume control system. Nothing is simple when you get into it!
Roger
Yves Smolders said:Dact is quite expensive.
I don't need motorized volume control - I'll have a nice receiver for normal operations (surround, easy listening) and will go with the passive volume coupled to the (modified?) DVD player for pure stereo. That's fixing the volume, sitting down and enjoy high end sound
So no different boxes, it'll only add to the complexity and adding cables/cable length - I guess there won't be too much noise from UcD's and the PS - I have them in a test setup now, an open case, with really bad signal cables (even bare wire parts in the signal wire) and it sounds sweeter than ever.
If it fails, I can still go with a seperate case
Yves,
Yes the DACT is expensive. I have been using it as there was not a worthy competitor. Now with the availability of the inexpensive ladder types this will change, unless they are just too big to fit. Sound quality should not be a problem as the signal only passes through a single Dale resistor in getting to the output.
I would recommend the 10k version as your DVD player will not have any trouble driving it and less resistance in line with the signal is always good if what is driving it does’t care. To keep noise pick up low the control should be mounted in the amp box and connected with twisted shielded cable. The output of the volume control is much higher impedance than the signal source so much more prone to noise pick up. If you are using bare separate wires you should at least twist them together in +/- signal pairs and keep them away from other wiring that carries high current. Twisting the leads together will cause induced noise to enter both wires almost identically therefore mostly canceling out.
As for noise pickup it is usually in two forms, electrostatic or electromagnetic. (The third way is with a direct connection, don’t overlook this!) This translates to either capacitive coupled or transformer coupled. With lower input impedance, as with a 10k volume control, the capacitive coupled noise sees a heavier load so will induce less voltage. Conversely, the transformer induced noise will enter a higher signal current so will be a lesser percentage. With the 10k control the signal current will be 5-10 times higher so the induced noise will be that much smaller in proportion. This is a very significant reduction and is worth while!
If the noise is high frequency the only effective means to reduce it are distance and shielding. Shielding can be in the form of ferrite beads on the wire pairs. This actually builds a transformer of a single turn with each wire causing equal canceling currents to be formed. There has been more than one design saved with a single ferrite bead.
Hope this helps your understanding of what is going on with this very simple volume control system. Nothing is simple when you get into it!
Roger
Revision 1
Ok I think I figured it out, I have a 2 ch ucd 400 kit on the way from Ken at digitalandanalouguediy. so i just need five more channels, so here we go again, now the 5 ch amp will only be used for the center and the surrounds and i will use the stereo amp for my mains so i could use the same PS configuration and then 3x 500 va transformers, also where can i get soft starts? Any one know of a company that makes a big chassis
Cheers, Carlos
PS, hey moderator how long am i under review for?
Ok I think I figured it out, I have a 2 ch ucd 400 kit on the way from Ken at digitalandanalouguediy. so i just need five more channels, so here we go again, now the 5 ch amp will only be used for the center and the surrounds and i will use the stereo amp for my mains so i could use the same PS configuration and then 3x 500 va transformers, also where can i get soft starts? Any one know of a company that makes a big chassis
Cheers, Carlos
PS, hey moderator how long am i under review for?
Roger,
Thanks for the story on noise pickup - I knew the basics about twisting cables (from my computer engineer background, network cabling and such) but it's good to read about it in such detail, and specific for audio.
I'll keep it in mind. First I want my 2 channel amp completed in a nice case, then i'll go further to improve my stereo-only listening using the switch and volume control.
Carlos,
I'm in Europe, so I got my things from Hypex direct. Got the UcD's and my PS from them, I'll get their softstart (due in about a month) from them as well (alternative is lcaudio) - only the transformer will be from somewhere else.
Thanks for the story on noise pickup - I knew the basics about twisting cables (from my computer engineer background, network cabling and such) but it's good to read about it in such detail, and specific for audio.
I'll keep it in mind. First I want my 2 channel amp completed in a nice case, then i'll go further to improve my stereo-only listening using the switch and volume control.
Carlos,
I'm in Europe, so I got my things from Hypex direct. Got the UcD's and my PS from them, I'll get their softstart (due in about a month) from them as well (alternative is lcaudio) - only the transformer will be from somewhere else.
Sorry if this is not the right thread, but now that you are talking about input and volume pot. optimal connections, I would like to ask something:
My amplifier board also has balanced inputs. I want to leave the option in the chassis to enter with unbalanced RCA or balanced XLR sources, so both connectors will be mounted.
For unbalanced, it is still good to run the cable from the module to the connector/s with the three lines (+, - and GND), and then join GND and - AT the input connector. But then, I ruin the - input for the XLR connector. How can I solve this?
Perhaps the only way is to run three wires to the XLR connector and then only the positive and GND to the RCA. But then, when entering with an unbalanced source, there will be more noise, as the - input is floating.
How is that solved in commercial amps?
Best regards,
Pierre
My amplifier board also has balanced inputs. I want to leave the option in the chassis to enter with unbalanced RCA or balanced XLR sources, so both connectors will be mounted.
For unbalanced, it is still good to run the cable from the module to the connector/s with the three lines (+, - and GND), and then join GND and - AT the input connector. But then, I ruin the - input for the XLR connector. How can I solve this?
Perhaps the only way is to run three wires to the XLR connector and then only the positive and GND to the RCA. But then, when entering with an unbalanced source, there will be more noise, as the - input is floating.
How is that solved in commercial amps?
Best regards,
Pierre
Pierre said:
My guess would be to use a switch to connect the - input to GND close to the input connectors in case RCA input is used. You could use some dummy XLR connector with the - input and GND pin shorted when you use RCA input, I think this was mentioned somewhere here before as well.
Best regards
Gertjan
There is a wiring diagram for this on the LCAudio site I think. Also it was mentioned in either this thread or the UCD180 thread recently. Basically I think the key was to add a large resistor between the two ground lines?
You should have no problem wiring them both up though. Sorry I can't point you directly at the reference now.
You should have no problem wiring them both up though. Sorry I can't point you directly at the reference now.
the Firstwatt F1 by Nelson pass does sort of what you want. There's a thread in the amps/passlabs section with a link to the service manual.
I think he wires the rca in parallel with the xlr connector like this: RCA+ to HOT, RCA- to COLD. When using the RCA connectors he shorts the GND on the xlr connector to COLD with a fixed piece of wire.
It defeats the purpose of the balanced connection but hey, you'll still be able to use it single-ended.
-- edit --
found it: this one, page 4 not that is a lot of help but you'll get the idea.
I think he wires the rca in parallel with the xlr connector like this: RCA+ to HOT, RCA- to COLD. When using the RCA connectors he shorts the GND on the xlr connector to COLD with a fixed piece of wire.
It defeats the purpose of the balanced connection but hey, you'll still be able to use it single-ended.
-- edit --
found it: this one, page 4 not that is a lot of help but you'll get the idea.
No this will be no problem. However use only a star wiring (all wires seperate from the power supply to the both amplifiers). And connect only one amplifier to the chassis ground. Connect only the both symmetrical input wires from the second to the first amp, the shield can be floating.
Regards,
Jan-Peter
OPA627 replacements
It was asked on other formums, and I never saw an answer. So you remove the dual 5532 or OPA2134, and somehow you sick in an OPA627. I'm told that is a single OPamp, with only 4 legs. so do you then uh take a pair and run them both back to back? Can someone educate me before I do something stupid? If you have to get an adapter, in case these are 8 legged chips, then gotta ask further what to do here. Thanks for the help guys.
Ray
It was asked on other formums, and I never saw an answer. So you remove the dual 5532 or OPA2134, and somehow you sick in an OPA627. I'm told that is a single OPamp, with only 4 legs. so do you then uh take a pair and run them both back to back? Can someone educate me before I do something stupid? If you have to get an adapter, in case these are 8 legged chips, then gotta ask further what to do here. Thanks for the help guys.
Ray