[orientalexpress]

i like Ted ideal  ,bridging with 4-ncor and 2 powersupply or 4-ncor and 4 supply?my speakers need alot powers..


lapsan

[hifial]

Yea, I will bridge or bi-amp, not sure yet what I will do. Some think I will be better off bi-amping (me) (my speakers are B&W 802D and can be bi-amp/wire) and others bridging with bi-wire (me). Well not just me but that is why I still have not made up my mind. If I have the funds I might do both, bridge four mono blocks. The B&W love power. They love to be bi-wired. So bridged and bi-amped, the Holy Grail!!   

[jtwrace]

Yea, I will bridge or bi-amp, not sure yet what I will do. Some think I will be better off bi-amping (me) (my speakers are B&W 802D and can be bi-amp/wire) and others bridging with bi-wire (me). Well not just me but that is why I still have not made up my mind. If I have the funds I might do both, bridge four mono blocks. The B&W love power. They love to be bi-wired. So bridged and bi-amped, the Holy Grail!!   

Where are you located?  Also, what's your system consist of?

[ted_b]

Anybody know how the Ncore modules bridge?  Are they reversible (say I have it done, then not solved a problem, could they be unbridged and retrofitted into a stereo config...new back panel or addtl binding post/XLR holes).

[TomS]

Anybody know how the Ncore modules bridge?  Are they reversible (say I have it done, then not solved a problem, could they be unbridged and retrofitted into a stereo config...new back panel or addtl binding post/XLR holes).

No there is no need for it to be "permanent". I haven't seen specific instructions for NCore but Hypex says it is the same as for the UcD series.
So, for a typical balanced connection, bridge tied load (BTL):
* hot(+) signal to amp module A hot(+) input and to amp module B cold(-) input
* cold(-) signal to amp module A cold(-) input and to amp module B hot(+) input
* connect the speaker load between the two positive amp outputs. Typically amp A would be the + side, amp B the - side. They recommend a 47nf cap across the output in that case. Note that NO output grounds (-) are connected.

Here is the wording from the Hypex UcD400 FAQ just for reference. I don't know how the impedance/current protection limitations would specifically apply to the NCore 400/SMPS600. The data sheet does rate them to 580w at 2 ohm loads (for 4 ohms bridged operation, with suitable power supply). I would also be sure the offset is properly adjusted in both.

UcD bridging

Q: I need double the power in an 8Ohm load than a UcD amplifier can produce. Is there some way I can bridge two, for example, UcD400’s?

A: You need to drive one of the modules 180 degrees out of phase by simply swapping the negative and positive input signal wires. Tie the loudspeaker between both positive loudspeaker outputs of the amplifiers and connect a 47n/200V capacitor across the loudspeaker terminals at the amplifiers’ side. This set-up is most applicable for 8 Ohm loads since each amplifier ‘sees’ 4 Ohms with an 8 Ohm load attached. A 4 Ohm load might trigger the current protection leaving you with not nearly as much power as you might have expected.

[hifial]

Where are you located?  Also, what's your system consist of?

Hi Jason. I am located just outside NYC, near Giants Stadium, in Nutley, NJ. I had a chance to hear your Ncore at Dan/letitroll98, Barry/barry-nj, Paul/occam and Martin/mjosef brought them to my house for three hours. Besides Martin, Barry and three members of one of the two audiophile clubs I belong to also came by and heard them. Unfortunately my system was in flux so not quit ideal. Only stock power cabling and no bi-wiring speaker cable for the B&W 802D (they love bi-wiring). No acoustical treatments and my B&W placement was a little off (they are spiked, so not easy to move). Because it was last minute I had to make due. Short version NO NOISE!! Did I say NO NOISE!! But it needs the right setup to be at its best. More in the "listening impressions" ASAP. 

My system consists of B&W 802D (first series), PS Audio Perfect Wave Transport, DAC MK II and Bridge. Transport is connected to the DAC by HDMI I2S and Bridge is hard wired by Ethernet. The DAC is true balanced and I use balanced cables to the amp, Nuforce Reference 18 mono blocks. Cables are Synergistic Research Galileo Universal Speaker and Interconnect Cells with Basik cables. Power Conditioning is Synergistic Research Tesla PowerCell 10 SE MK II with Tesla Se Precision power cord. Vibration control is Finite Elemente Cerapuc. My rack is Salamander. Music is CD and High Res downloads. I bi-wire to the B&W 802D. 

Holy Grail I: 4 NC1200 as 4 mono blocks bi-amping the B&W. (maybe bridged, 8!) if there was a way to do OEM.
Holy Grail II: 8 NC400 Bridged as 4 mono blocks bi-amping the B&W.
Holy Grail III: 4 NC400 as 4 mono blocks bi-amping the B&W.
Holy Grail IV: 4 NC400 Bridged as 2 mono blocks bi-wiring the bi-amping.

Well first I have to sell my Nuforce Ref 18s. Any takers? I will use the time to research and decide what number to go with (assuming I do not think of another choice).
 
Thanks for the tour.
 

[ted_b]

Has anyone actually seen power specs for the bridged Ncores?  I have a 3 day old email into Hypex but nothing yet. 

[kevinh]

I believe the specs aree 600w/8ohms. 1200W/4ohms. No rating for 2 ohms

[hifial]

I believe that it is +/-1800W/2ohms and you are right on the 4 and 8  ohms.

[mgalusha]

I'd be very leery about running them bridged with a 2ohm load, each amp would only see 1ohm and the Hypex data sheet doesn't rate them for that.

Also, with 2 x SMPS600 power supplies, only 1200W is available.

[kevinh]

I'd be very leery about running them bridged with a 2ohm load, each amp would only see 1ohm and the Hypex data sheet doesn't rate them for that.

Also, with 2 x SMPS600 power supplies, only 1200W is available.

It's just a matter of knowing the impedance of the speakers being used and if the impedance dips to what frequencies that happens at.

If you are looking at an electrostatic for example the low impedance is at higher frequencies where there isn't a lot of energy so the current shouldn't be an issue.

[ted_b]

I'd be very leery about running them bridged with a 2ohm load, each amp would only see 1ohm and the Hypex data sheet doesn't rate them for that.

Also, with 2 x SMPS600 power supplies, only 1200W is available.

Mike, do you mean 1 SMPS600 per chassis (2 modules) ?  Is 1 PS per chassis recommended, regardless, or would you do 2?

[TomS]

Mike, do you mean 1 SMPS600 per chassis (2 modules) ?  Is 1 PS per chassis recommended, regardless, or would you do 2?

A single SMPS600 can source ~600 watts for music, so for 1200w you'd need a couple of them.

[hifial]

Just got the following replies on DIY.

     #4254
Juhleren is offline Juhleren  Denmark
diyAudio Member
 
Join Date: Mar 2011
   
Quote:
Originally Posted by hifial View Post
In bridged mode the NC400 puts out 600w/8ohms-1200w/4ohms and what in 2ohms?

In bridged mode how many power supplies (smps) do you use or can use per bridged modules mono blocks?

If bridged, can the NC400 drive a 2ohm load?

.
Al, If you bridge NCORE´s you should theoretically get 2x(what one can do in 4ohm) in 8ohm = 800W/8ohm. (twice the voltage swing and twice the current)

In a 4 ohm load you begin to hit the current limits as you now get twice of what it can do in 2 ohm = 1200W/4ohm.

In a 2 ohm load you are definitely hitting the current limits as each module can deliver 24 A and therefore each "only" swing 24 V into the 1 ohm they "see". That should give you roughly 24*24 = 576 W RMS and 1152 W Peak for the bridged amp.

Under such conditions I would give those amps as much current capacity as they can eat, so minimum a SMPS600 each. You could also consider to feed two NOCRE´s on a SMPS1200 which should save you some money...

This means that you should only benefit power-wise in above 2ohm loads where you get a whopping 1200 W RMS in 4ohm and 800 W RMS in 8 ohm.

Whether there should be any SQ differences has yet to be reported. But if you should try to bridge, then please report your findings

cheers,

waltzingbear is offline waltzingbear  United States
diyAudio Member
 
Join Date: Nov 2005
Location: Portland. Oregon
   
Quote:
Originally Posted by hifial View Post
I have heard them with the B&W 802D. They are my speakers and a set of Ncore NC400 mono blocks that were loaned to me. I never said they sound strained or clipping when I have had more power and or the Ncore.
didn't mean to imply that. If you really want to know whats going on, measure the voltage being delivered to the speaker with a peak reading meter. The ones I am familiar with are the Fluke189 or 289.

With the ncore and other amps as long as you are within the voltage limits of the amp, you actually have more power for control of the speaker without bridging. The current capability is halved with bridging, and this is the area a lot of speakers "care" about. Doubling of the output impedance also goes along with this, which will double frequency response errors due to output impedance / load interaction. The way I see it, bridging is less power to the speaker, for most of the time.

If a designer was to build symetrical (ie bridging) operation into the design and incorporate the real world current needs of speakers into the design, that might be very interesting as a real (designed) push-pull system has many interesting features.

I have tried bridging independent amps in the past, was never satisfied with the results.

Alan

From Alan's post I have less interest in bridging the Ncore. Current is important to me just as much as watts. Unless someone can give me an over riding benefit, I am not bridging them. Any thoughts?

Al.

[hifial]

hifial is online now hifial  United States
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Join Date: Feb 2011
Location: New Jersey, USA
   
Quote:
Originally Posted by Juhleren View Post
Alan I would believe too that bridging wouldn´t be a necessity for most well designed speakers driven with NCORE.

That said, and I suspect that we have been over this before, but bridging should not half the current capabilities of an amp, unless you run into other problems such as stability issues... We probably agree that with bridging each amp only sees one half of the load. But at the same time each amp also only needs to do half the work voltage-wise which means that they have to deliver exactly the same amount of current for the same total output to the speaker.

Effectively this means that where one amp would limit due to current capabilities it still will when bridging (same output potential) and where it would limit due to voltage swing you´ll get twice the potential swing of voltage.

Remember that both amps contributes hence their increased current output only occurs when you also have increased output power. The impedance of the speaker still follows Ohm´s law...

I understand that you don´t like what bridging does in the cases that you have tried it, but have you tried it with NOCRE´s?
That would still be interesting to try as the increased potential voltage swing possible could materialize into audible gains...

cheers,

AH! And the plot thickens. I guess I (we at AC) need to investigate this further. If I buy larger chassis for them and put in single mods and have room to bridge at a later date if I find out it would be worth it might be a way to go.

[kevinh]

Wonder of the SMPS 600 is regulated differently than the SMPS 1200?

Since the NC 400 has up to a +-75 V PS capability sounds like you could use a couple of smps 1200.

BTW the NC1200 has a +-100 V max rating.

[hifial]

And the plot thickens.

Al.


Juhleren is online now Juhleren  Denmark
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Join Date: Mar 2011
   
Quote:
Originally Posted by waltzingbear View Post
Maybe I'm missing something here, but we can't have it both ways.

If the amp sees half the load, say 1.7 ohms instead of 3.4 ohms, it will potentially become current starved before the single amp configuration at the same volume level. Its not that the amp is any less capable when bridged, its that it sees half the load value. I'm not concerned with the voltage limiting, until someone measures and says they have peaks exceeding +/- 65V longer than 2 sec, I don't think voltage clipping is an issue.

Current is what I am referring to. The Ncore is rated into 2 ohms, how much below that I do not know. But we already see it sagging at 2 ohms. Current limiting is irrespective of voltage level (until we get to SOA concerns, which are negligible in class D amps)

Hence my comment that a single amp is better at delivering the power to the speaker within its voltage range. Yes, this is less than peak power with bridged amps, but I don't care about peak power, I care about current delivery in the area of concern, during the time it is below the voltage limitations of the single amp.

Does that make my view point clear?

Cheers,
Alan
Yes, you do seem to only look at one amp (one half of the bridge) and not the bridge as a whole (being one amp on the "hot side" and one on the "cold side" of the speaker).
One amp (one side) sees only 1,7R of 3,4R total but also only delivers half the voltage swing (for the same output power and current as a non-bridged amp would).

That means that a bridged amp can deliver as much power and current, but at only half of the voltage swing seen from each "amp" in the bridge.

Together they deliver the same total voltage swing and the same total current as a non-bridged amp would. The bridged config can´t deliver more current, but then it doesn´t have to either.

Lets take a quick n´dirty math example to make my point more clear:

non-bridged:

3.4R x 24A = 81.6V peak (this would in practice result in clipping due to the max 65 to 72V supply limitations, but if we overlook this we would end up with-> 81,6*24 = 1958.4 W peak and 979,2 W RMS both at 3,4R)

Bridged:
only one module:
1.7R x 24A = 40.8 V peak

both modules in the bridge will then deliver: 2 x 40,8V = 81,6 V peak
One module delivers +40.8V and the other -40.8V = total voltage potential on the terminals being the 81,6V

This then provides the 1958,4 W peak and 979,2 W RMS well within the voltage limits of 65 to 72 V per module

In comparison one module with one smps600 should according to the +/-65V "only" be able to deliver 65/3.4R = 19.12A which gives 19,12 x 65 = 1242,6 W peak and 621,3 W RMS @ 3.4R

The bridge is according to the math more powerful in a 3.4R load.

The point at which the bridge is only equally powerful to the non-bridge is in a 65V/24A = 2.7R load.

Hope that helped

cheers,

[ted_b]

I received an email reply from Jan-Peter at Hypex.  I asked him, also, whether the briding causes a halving of current??

Ted,

No this is not true. The maximum current in bridging stays exact the same, with two amps you will have double the output voltage and exact the same output current. Please note that you need to use two SMPS600 if you go for bridging.

Regards,

Jan-Peter

[jtwrace]

Please note that you need to use two SMPS600 if you go for bridging.

Is he saying that you would need two SMPS600's for each pair of NC400's?

[Barry_NJ]

The Power Supply question is an interesting one...

The SMPS600 specs out as...
ELECTRICAL FEATURES:
- High Line Input Voltage: 180-264 Vac
- Low Line Input Voltage: 90-132 Vac
- Output Voltage: 2x65Vdc
- Max. Output power: 650W
- Max. Output power: 600W @20Hz
- Switching Frequency: 100kHz

and the SMPS1200A700 specs out as...
ELECTRICAL FEATURES:
- High Line Input Voltage: 180-264Vac
- Low Line Input Voltage: 90-132Vac
- Output Voltage: 2x85Vdc
- Max. Output power: 1500W
- Max. Output power: 1200W @20Hz
- Switching Frequency: 100kHz

and the SMPS1200A400 specs out as...
ELECTRICAL FEATURES:
- High Line Input Voltage: 190-250Vac
- Low Line Input Voltage: 95-130Vac
- Output Voltage: 2x64Vdc
- Max. Output power: 1500W
- Max. Output power: 1200W @20Hz
- Switching Frequency: 100kHz

So it would seem as though the SMPS1200A400 has an "Output Voltage" that matches the SMPS600, but the SMPS1200A700 has "High Line Input Voltage" and "Low Line Input Voltage' that match the SMPS600, and both offer double the "Max. Output power". I wonder if one of these power supply modules would work nicely with 2 bridged NCORE amplifier modules(?) Having heard the dead quiet provided by the SMPS600 I'd be a bit affraid of messing with something that really works.