Does anyone bi-amp with multichannel amp?

[sjcguy]

Have anyone used multi-channel amplifier to bi-amp speakers? The setup is to use 4 out of 5 multi channel amp instead of two 2ch-amp? does it sound weird?
thanks
tran

 

[Seth=L]

It won't sound any different unless the output limitations in 4 channel vs. 2 channel have changed. If the amplifier is like most multichannel amplifiers then all channels get their power from the central power supply. Also, most multichannel amplifiers have robust output stages of equal value dedicated to each channel that are capable of delivering large quantities of power exceeding the ACD rating.

A real improvement would be possible with the addition of an active crossover and bypassing the speaker's passive crossover entirely. Bi-amping is required if you intend to run an active crossover. I doubt a significant audible change will occur with bi-amping alone.

 

[walter duque]

You can check it out and try it. Nothing to loose but a litte time. I did it but I ended up going back to normal. Passive bi-amping I didn't notice any change. What amp and speakers do you have?

 

[sjcguy]

I have two pairs of Polk RT16. For HT, I have Sony STR-DA5ES + HK PA5800.
I am looking for a new amp for my 2ch music setup. Either UPA-2 or UPA-5 ( bi-amping).
Any way I just reserved a UPA-2 to take advantage of free shipping but i don't know if it's applied to UPA-2 since it's back order.
tran

 

[PENG]

I have two pairs of Polk RT16. For HT, I have Sony STR-DA5ES + HK PA5800.

5ES? You mean one of those rare 21 kg (46.2 lbs) 6 channel AVR that has a Sony ES brand transformer instead of the later model's (4ES) Bando transformer? Since you mentioned it, are you planning on using its preamp to work with the UPA-2 for stereo? If so, I doubt you will gain much as the 5ES will likely give you almost as much power if the power supply has to feed only 2 RT16 that are 8 ohms nominal and 90 dB sensitivity. The XPA would be a better match if you want to fully satisfy those big towers under any circumstances.

 

[sjcguy]

Yes, it's the one that was highly praised by Sony community. For unknown reason, I felt the sound was so thin when playing 2ch music and it's better when I added the HK PA5800 to power front and center channel. Probably I will do a A/B comparison again to see whether I need the HK amp. XPA-2 is definitely out of question, to big and too much judging from my setup and the time I have for it. I am not be able to decide between old amp from local craigslist or new amp with warranty. If I buy emotiva, I will pick one of these: UPA-2, XPA-5 or XPA-3. One crazy idea is that to buy XPA-3/5 to use 2 ch only and i can later move to power my HT.
tran

 

[AcuDefTechGuy]

Most of us have bi-amped and tri-amped in the past.

Most of us find that it makes very little difference, if any difference at all.

Most of us find that the amps/pre-amps also make very little difference in Direct modes (EQ, Tones, DSP bypassed).

It is the speakers and the placement of them that make the biggest difference.

 

[sjcguy]

I did a quick A/B test today: sony STR-DA5ES vs HK PA5800 to power the polk RT16. W/O the amp, the music sounded hash and the bass was very weak. But when I sent the pre-out from the Sony to the HK amp and kept the same volume setting, the music became alive and opened up and louder. I could tell the high notes from different instrument, vocal sounded so sweet and warm and it didn't irritate the ears. I am surprised that the highly praised Sony ES sounds that bad or the HK PA5800 was overlooked. My wife didn't know and care what I was doing but she could tell which one sound better. I am convinced I need an amp for my 2ch setup.
tran

 

[bandphan]

I did a quick A/B test today: sony STR-DA5ES vs HK PA5800 to power the polk RT16. W/O the amp, the music sounded hash and the bass was very weak. But when I sent the pre-out from the Sony to the HK amp and kept the same volume setting, the music became alive and opened up and louder. I could tell the high notes from different instrument, vocal sounded so sweet and warm and it didn't irritate the ears. I am surprised that the highly praised Sony ES sounds that bad or the HK PA5800 was overlooked. My wife didn't know and care what I was doing but she could tell which one sound better. I am convinced I need an amp for my 2ch setup.
tran

Unfortunately your method doesnt yield a true result. The units need to be level matched, not just with volume, and your wife would need to switch between the two so you wouldnt know which was which. If you do decide to go with a separate amp, as mentioned move into the 2-300wpc range. Crown is upgrading their XLS line and you can get the 202 for $149 free shipping the 402 $199. (200wpc and 300wpc into 8 ohms)

 

[sjcguy]

when I played the music w.o the amp, i turned the volume to the level I normally listen. But with the amp, It was more dynamic, wider and live.
The receiver is rated 110W/ch and the HK PA5800 is rated 80W/ch. How come the volume is louder with the amp?

 

[bandphan]

when I played the music w.o the amp, i turned the volume to the level I normally listen. But with the amp, It was more dynamic, wider and live.
The receiver is rated 110W/ch and the HK PA5800 is rated 80W/ch. How come the volume is louder with the amp?

Manufactures' specs are to be taken with a grain of salt. You need credible 3rd party measurements to check. As for loudness, level matching is essential as the output voltage of the pre outs to the HK may be different.

 

[AcuDefTechGuy]

How come the volume is louder with the amp?

Because the voltage gain on the external amp is higher.

For example, the voltage gain on the receiver's amp may be 28dB, but the voltage gain on the external amp may be 32dB.

 

[Seth=L]

Does anyone here seriously think the STR-DA5ES can outperform the PA5800 in output? Did someone take silly pills this morning?

The PA5800 has pairs of 10,000uF capacitors dedicated to each channel, totaling 100,000uF, paired with a large toroidal transformer easily 650va or more. H/K always gives their ratings as ACD typically with very low THD. It's also more stable into difficult loads than the Sony.

 

[AcuDefTechGuy]

Does anyone here seriously think the STR-DA5ES can outperform the PA5800 in output? Did someone take silly pills this morning?

I would never buy a Sony receiver.

When Sony says it is 100WPC, it will probably measure 20WPC from 20Hz-20kHz all channels driven.

 

[bandphan]

Did someone take silly pills this morning?

I did
That model Sony was pretty descent.

 

[Seth=L]

I did
That model Sony was pretty descent.

I'm not doubting the Sony STR-DA5ES is decent, it's an excellent receiver to be sure. That said, it's a receiver therefore it cannot be considered equal to a power amplifier of this class in relation to its output capabilities. I think this is a fair assessment. Compare the filter capacitance of 30,000uF to the PA5800's 100,000uF and include the factor of the larger transformer who's sole duty is to deliver power for amplification only. Also take into consideration the heavy duty heatsinks fitted with 4 high power transistors per channel versus two on the Sony. The transistors on the Sony are excellent quality, don't get me wrong, but I'm willing to bet the quality of those found in the H/K are similar and also more numerous.

 

[bandphan]

^ agreed

 

[PENG]

^ agreed

Me too, but I suspect his findings may indicate there is something wrong with that Sony. The 5ES has a decent transformer. I know so because I have removed the inferior (to the 5ES) Bando transformer from the 4ES a couple of times. That thing alone probably weighed 8 lbs and the 4ES weighed 21 kg as a whole soak and wet. The 5ES weighs about the same with 1 channel less. I thought you guys like to deduce power from weight, no, not this time? Mind you I did feel the 6 to 8 lbs lighter 3805 that replaced my 4ES had more power; and I never did feel weights mean a whole lot myself. It meant somethiing, but only to a point.

Further, as Seth himself said something about using multichannel amp for 2 channel applications earlier, here we are talking about a decent power supply in the 6 channel 5ES having to power only 2 channels, not ACD. The OP said he was listening in 2 channel and it sounded thin. Well I certainly did not share that experience with the 4ES (again, inferior to the 5ES) as my 87 dB sensitivity tower speakers did fine with it way back then.

I repeat, I agree with Seth's comments about the comparison between the two and have no doubt the HK is much more powerful, but I admit I am somewhat skeptical about the OP's findings. Of course I believe him, but I can't help but wonder if something else may be at play.

 

[Seth=L]

The 5ES weighs about the same with 1 channel less.

Oh come on, that's easy.

Well, we could make put in a larger VA transformer for the extra channel and put more fins on the heatsink

Why?

So the receiver can still meet a similar multichannel demand.

Actually, it won't make much of a difference. We'll just fit two more transistors on the heatsink and use the same size power supply. The two channel performance will be virtually the same as before, and that surround back channel won't get used much anyway, much like the surrounds

Point taken, we won't change anything accept for the space between transistors and their connections to the board.

Mystery solved.

 

[PENG]

Does anyone here seriously think the STR-DA5ES can outperform the PA5800 in output? Did someone take silly pills this morning?

The PA5800 has pairs of 10,000uF capacitors dedicated to each channel, totaling 100,000uF, paired with a large toroidal transformer easily 650va or more. H/K always gives their ratings as ACD typically with very low THD. It's also more stable into difficult loads than the Sony.

This is taken from the PA5800 manual:

Weight: 30 lbs/27.3 kg
120VAC, 50 Hz / 60 Hz
340 watts, maximum

Nothing makes sense?? 30 lbs=13.6 kg not 27.3 kg and 340W max would not correspond to/imply a 650VA transformer. Of course, you may be right and HK website may be wrong (seriously). FYI I did a copy and paste so there is no typo.

Don't forget in 2 channel, the Sony has the whole P/S including the capacitors all used for the 2 channel whereas according to you data, the HK's are for each individual channel.

Regardless I still believe the PA5800 is much more powerful than the 5ES but without seeing some detailed specs (what's on the manual is not clear enough for me) it is just my guess. If you read this review, the HK may not be as great as you think it is though.

http://www.hometheaterhifi.com/volume_10_2/outlaw-audio-7100-power-amplifier-6-2003.html