Parasound HCA-1500A power amp output specs

GATOR3000

My Parasound HCA-1500A power amp output specs are as follows:

Continuous Power Output:
205 Watts RMS x 2 into 8 ohms
315 Watts RMS x 2 into 4 ohms

Continuous Power Output – Mono (Bridged):
630 Watts RMS x 1 onto 8 ohms

My question is about operating the amp bridged.

For example, if you are powering Rti8 speaker (rated at 8 ohms) I understand the 630 Watts into 8 ohms (bridged) power output.

What is the power output if one is powering Lsi15 speaker (rated at 4 ohms)? Would the power output double to 630 Watts x 2 = 1260 Watts into 4 ohms? This doesn't look right! Please help thanks.


Gator

steveinaz

Can't run the HCA at 4ohms/bridged. Parasound states this in the manual.

AndyGwis

That seems to be the norm with most amps. Bridged is only advised and rated for 8ohm speaks. Anything lower and you might be in for some trouble.

jdhdiggs

Besides, looking at the unbridged mode, that amp can't "double down" at 8 Ohms anyways. I would bet your max wattage would be 630W regardless...

BTW: Why on earth would 315W not be enough?

GATOR3000

jdhdiggs wrote:

BTW: Why on earth would 315W not be enough?

I didn't imply 315 Watts is not enough. I was just not clear if one can run the amp bridged with 4 ohm rated speakers. Now I understand. Thanks for the clarification guys.

Gator

disneyjoe7

In bridged mode an amp see a 8ohm load as 4ohm, this is why an amp not spec'd for 2ohm load can't run 4ohm load bridged.

GATOR3000

steveinaz wrote:

Can't run the HCA at 4ohms/bridged. Parasound states this in the manual.

steveinaz,

I looked at the pdf manual on Parasound web site. In the bridged mode each channel of the amp “sees” only half of the speaker’s impedance. For a 4 ohms speaker, the impedance would be only 2 ohms per channel.

I didn’t get the amp with manual. I did download pdf manual now.

Thanks bro.

Gator

dkg999

If the Rti8's can be bi-amped, I would use the 1500's in a vertical bi-amp configuration. This is similar to using each amp bridged, however you use one channel for the mid/tweeter and one channel for the lower/woofer.

GATOR3000

dkg999 wrote:

If the Rti8's can be bi-amped, I would use the 1500's in a vertical bi-amp configuration. This is similar to using each amp bridged, however you use one channel for the mid/tweeter and one channel for the lower/woofer.

That means I would need 2 1500's to run 2 RTi8's in bi-amped mode.

jdhdiggs

dkg999 wrote:

If the Rti8's can be bi-amped, I would use the 1500's in a vertical bi-amp configuration. This is similar to using each amp bridged, however you use one channel for the mid/tweeter and one channel for the lower/woofer.

Why? Why not have all the power transistors available to the entire speaker? Why break the power reserves in half?

Remember, woofers are typically less efficient than tweeters and each octave drop in frequency requires a doubling of power to maintain the same dB level. The end result is that the tweeter section represents an insignificant load compared to the woofer sections. What you have done in bi-amping is effectively freed up you tweeters load from the woofers giving the woofers an extra watt or so in extra power. The tweeter section will only load the upper amp with maybe 2W at screaming dB levels. Bridging them, he gains >400W.

In this case he should absolutely bridge the amps if he wants more power, not bi-amp. Better case: sell both amps for an even better one.

jdhdiggs

GATOR3000 wrote:

That means I would need 2 1500's to run 2 RTi8's in bi-amped mode.

Yup, double the cost for what amounts to about 2-10W (MAX) of extra power in real terms.

dkg999

I can't argue with your logic, however I use two HCA-1500's vertically bi-amped to run my Magnepan 1.6QR. I experimented with horizontal bi-amping, and using one amp to power both speakers. The vertical bi-amping really made the Magnepan's come alive. I did it at the suggestion of a Parasound tech who gave me an equally plausible sounding explanation as to why you should always vertically bi-amp with the HCA series of Parasound amps. All I know is that it worked the best. Your mileage may vary!

jdhdiggs

Maybe the HCA do something different, I know some Carver amps ratchet up the distortion in bridged mode. I still think one amp for double the price would be the better option. Go grab a pair of JC-1's!

For your maggies, go get a line level crossover and take out the external X-over and then write me a thank you note.

dkg999

You are correct, the external cross-over would be an improvement. I am just not ready to take that jump yet. I just added a Rogue Audio Magnum 66 pre I got from Russman, and it made a nice improvement over the Audcom 110 I was using. I'm really happy with the system at them moment. I need to get moved to a new place and then I won't have the Maggies boxed in with other furniture, and then I can evaluate where I want to go with them. I have looked at the external cross-overs, and haven't been able to get a solid opinion base on which one to purchase if I did want to play with one. Any thoughts? Doug.

jdhdiggs

For $25 delivered, not much risk... I'm using a 500Hz high pass on my knights and nothing on the adcoms. I could probably add a 1.5 kHz low pass to the adcom but I don't think that the tweeter signal is pulling too much of the 400+ Watts available.

Check the x-over for the 1.6 QR (600Hz?) In that case a 500Hz one would be just fine. The next step down is 150Hz I think (Parts express line level x-over). The 150 would still eliminate a huge amount of load off the amp.

dkg999

Thanks, I'll take a look at those options! Doug.

jdhdiggs

Oh yeah, and since your speakers are 4Ohm, you wouldn't want to mono those amps for the reasons above.

dkg999

I agree! I was cautioned about that by the same Parasound tech. The Maggies seem to be a little challenging for amps to handle according to a lot of what I have read. I do like the sound of the Parasound amps when used with the 1.6's.