Modifing a Crestron 16x60 amp to make it bridgeable

[CharlieLaub]

Hello to all. I apologize for the stupid questions. 1) How do two channels of 60W produce not 120W but 200W? Did someone measure the actual power output ???
2) It is important not only power but also current. Does the current increase with such a connection in parallel and how does the Damping Factor change.
3) Maybe I misunderstood the modding scheme, but is it possible to put an already amplified signal from the preamp to the amplifier input?
4) I did not find the amplifier circuit, as well as the detailed photos of the transformer. There are two versions of international and usa. International is rated for 220V, American for 120V. Is it possible to remake the American version for the European?

The amps produces 60W into 8 Ohms. When you bridge two channels into an 8 Ohm load, each channels has a 4 Ohm load on it. The amp is rated at 90W into 4 Ohms, so it is not a stretch to see how two 90W channels can reach 200W when used together. If you do not grasp these concepts then do not attempt!

 

[Michael Bean]

Hello to all. I apologize for the stupid questions. 1) How do two channels of 60W produce not 120W but 200W? Did someone measure the actual power output ???
2) It is important not only power but also current. Does the current increase with such a connection in parallel and how does the Damping Factor change.
3) Maybe I misunderstood the modding scheme, but is it possible to put an already amplified signal from the preamp to the amplifier input?
4) I did not find the amplifier circuit, as well as the detailed photos of the transformer. There are two versions of international and usa. International is rated for 220V, American for 120V. Is it possible to remake the American version for the European?

1) The power output calculation is: Volts squared divided by the load resistance (or impedance).
So in the case of a 60 watt amp and a presumed load of eight ohms: (22 * 22) / 8 = 60.5 watts. When you implement a bridge-tied load the voltage across the load is (theoretically) doubled, so: (44 * 44) / 8 = 242 watts. But the fact that all amps have limited output current capabilities, the delivered power is usually less than theory would suggest.

2) Damping factor in a BLT will be half that of an equivalent single ended amp.

3) I'm not familiar with the equipment discussed so I can't comment.

4) The power transformer must have dual primary windings, usually two 120 VAC that can be wired in series or parallel to accommodate different mains voltages.

Mike

 

[GermanTwinov]

1) The power output calculation is: Volts squared divided by the load resistance (or impedance).
So in the case of a 60 watt amp and a presumed load of eight ohms: (22 * 22) / 8 = 60.5 watts. When you implement a bridge-tied load the voltage across the load is (theoretically) doubled, so: (44 * 44) / 8 = 242 watts. But the fact that all amps have limited output current capabilities, the delivered power is usually less than theory would suggest.

2) Damping factor in a BLT will be half that of an equivalent single ended amp.

3) I'm not familiar with the equipment discussed so I can't comment.

4) The power transformer must have dual primary windings, usually two 120 VAC that can be wired in series or parallel to accommodate different mains voltages.

Mike

Thanks for the detailed answers, Mike!

 

[Dennis F]

Hi all,

I've recently procured a CNAMPXI-12X60 (230v version) and wanted to change the control circuit in a similar fashion as others in this thread. Changing this in mine was easy as it was just ensuring a 24v output on an internal connector.

Conveniently enough the positive side is already connected. All that was left to do was to couple the ground. You can see the relevant bits and bobs in attached images.

Thank again for this thread! Triggered me to buy one of these amps and so far it's great

 

[Oaklandraiders]

I would not keep posting your phone number...

I will first assume that you have figured out how to use this amp as a power amp. try to answer them.

Hi, 1st post go easy on me !
I think I've got it but to confirm, I buy a 24v power supply, cut off the end adaptor, get a phoenix connector and then on the back of amp, one goes to 24v, one to G ? Which wire is which ?

Then the amp will work as a regular power amp ?
Can I bridge without doing any soldering etc
4ohm speakers

Thanks

 

[AllenB]

If you get yourself a meter (eg. a DMM) , you can discover the polarity of your supply.

 

[robertfoo]

Bridging the Crestron CNAMP Power Amp

Wait a minute, I just remembered that my receiver has XLR outputs. DUH! So could I just use the above mentioned XLR breakout cable to convert the output to dual RCA's - one with a hot pin, the other cold?

I have an Oppo BDP-105 which has an XPR stereo out on the back. I am interested to know if you had this working.


I am not a electrical engineer by ant stretch, but am pretty good at DYI electronics, I can make up an XLR/RCA splitter but not sure of the Hot and Cold wiring and to which RCA inputs they would go to on the power amp. It seems so obvious but I just don't want to risk blowing up my amp.


I am not 100 sure of the connections of the output side of the power amp as well. ie: am I to wire the two +hot outputs together and don't wire the two cold (assume they are common). If I wire two channels that 2 x 60 = 120! That is L/R or is it four channels Ch1/2 L+L, R+R Ch3/4 L+L R+R.


Diagrams will help.


Am I making sense?


Regards.

 

[niterida]

Can I use these for the RCA to Balanced RCA requirement for bridging ?

Unbalanced to Balanced Output Stereo Converter Board Low distortion DRV134PA x2 | eBay

Or is it easy (and cheap) enough to do the internal bridging as per the initial post ?

 

[niterida]

Can I use these for the RCA to Balanced RCA requirement for bridging ?

Unbalanced to Balanced Output Stereo Converter Board Low distortion DRV134PA x2 | eBay

Or is it easy (and cheap) enough to do the internal bridging as per the initial post ?

Ignore that - I figured out a way I can use my MiniDSPs instead

 

[robertfoo]

Btw in australia jacar electronics have the right sized pheonix connector for the 24v adapter.

 

[Spilgrim]

Does anyone know if Whirlwind LM2B can be used instead of Henry Engineering The Matchbox HD?

 

[HexFET]

FWIW, I have successfuly used the Radio Design Labs (RDL) fp-ubc series depending on how many unbalanced-balanced channels you want to bridge.

As the FP-UBC are 24-vdc powered, I just use the Crestron CNPWS-75 power-supply to "activate" the CNAMPX and power the balance converter.

neil

https://www.ebay.com/sch/i.html?_fr...t=0&LH_TitleDesc=0&_odkw=rdl+fp-ubc&_osacat=0

https://www.ebay.com/sch/i.html?_fr...89.m570.l1313&_nkw=CRESTRON+CNPWS-75&_sacat=0