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Home theater with stereo amps- experiment done

AV Cables

Amarendra

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Hi,

As discussed earlier on the forum I managed to experiment with a stereo amp based HT set up. The people at Norge Audio in Mumbai (Mr Laxman) were kind enough to let me carry my PC to their workshop. They connected the analog outs of the motherboard to 3 different amps (model 4242). These amps were connected to varying bookshelf speakers. One large book shelf speaker was used as a subwoofer since there wasn't one on hand. For surrounds we used the smallish Norge Nano speaker set.

Once connected we tried multiple sound clips from movies such as- The Book of Eli, Avatar, Star Trek, Bajirao Mastani, Lord of the Rings, THX demo, a demo disc from DTS etc.

Initially all speakers were kept in the front which was causing some muddying of sound but once separated, the surround effects were surprisingly sharp and accurate.

When playing Avatar, i experienced a sound-field which was phenomenally large and loud. The amps were brimming with energy and even minor details in the track such as the rustling of leaves received adequate attention and power.

Bajirao Mastani's initial court scene where Bajirao presents his candidature to the court is my favorite since it offers a lot to test- ample dialogues, followed by silence then the scene where the bow is stretched and then the applause.
The amps gave a feeling that I was watching the movie in a movie hall. Such was the scale and power.
The "mastani" song played phenomenally well.

However while playing a demo from pirates of the carribean, the experience wasn't so immersive and felt a bit disjointed.

The Norge people attributed this to three things- one is the lack of proper matching of speakers, their placement and the absence of a certain mpc or mpx circuit which it seems is present in AVRs which gives it the ability to deliver crystal clear sound. However they mentioned that the sound could be improved with software or proper placement of speakers.

Barring the above I was tempted to buy the 4242 amps to build my HT with Wharfedale speakers.

Some of the pros and cons:

+ Ample power and headroom for all channels
+ plenty of flexibility
+ no headaches of HDMI board replacement/ repairs (quite common these days)
+ price
+ ability to swap amps as per liking
+ cheap repairs if required

- Not a neat solution (one box types)
- No audyssey/ YPAO/ MCACC
- all amps were running at 12 o clock volume (weak pc signal ?)
- no remote
- lack of whatever filter that these ppl were talking about
- slightly accentuated higher frequencies

Can some of you with technical/ engineering background shed some light on this ? Can the sound signature be improved with software adjustments?

Thanks
 

newlash09

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Hi amarendra....

Thanks for the nice write up. Interesting experiment indeed. You almost had a Pre+Power combo there.

All the main stream AVR's from consumer brands ( Marantz, Yamaha, pioneer etc ) quote the power of their AVR in 2 channel mode. So my Marantz SR 6011, is quoted as 110W x 2ch @ 8 ohms ( 0.08% distortion ), same is again quoted as 150W x 2 ch @ 6 ohms (0.7 % distortion at 1 KHz ). So for marketing purpose they print it as a 9.2 channel AVR with 150W. But if a particular movie track is played, where all channels have sound output, you'd be surprised to know that the same Marantz will struggle to pump out even 35 W per channel. And also bear in mind that the Marantz's distortion increases to a whopping 10% at 6 ohms, when played to output 220 W into even a single channel. So, even these brawny looking AVR's are brittle in the sound department. And it is always advisable to use high sensitivity speakers with AVR's.

The Norge 4242's you used, have a clean 35W per channel into 8 ohms with dynamic head room to spare. So they are not deficient in power compared to the beasty AVR's.

And coming to why it sounded different is :

1) A bookshelf speaker was used in place of a proper sub-woofer. So deep bass was missed out on.

2) There was no room correction in place, to adjust for room gain.

3) The norge's have a frequency response of 45 hz to 20 kHz. So they are weak in the low end. So, Iam not surprised that you found the system bright. And as per the Norge's specs, they are indeed bass lean.

If you like to use Norge 4242's for home theatre purpose. We need to add room correction and subwoofer integration into the mix. So, any used AVR with pre-outs and room correction can be used for this. And in m opinion, with all low end duties being passed to a sub, the norge amps will open up further. And you should have a stellar HT setup. All the best :)
 

MaSh

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Excellent experiment. I am sure with some more fine tuning and correct placement and levelling of speakers, the sound can be improved by a lot.

Also which software did you use to play the content? What was the output from pc? You could try adding a multi channel preamp which can take a digital input.

MaSh



Sent from my Redmi Note 3 using Tapatalk
 

Amarendra

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Noted your points but these HT pre- amps cost a lot which will defeat the purpose.
 

elangoas

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These amps were connected to varying bookshelf speakers. One large book shelf speaker was used as a subwoofer since there wasn't one on hand. For surrounds we used the smallish Norge Nano speaker set.

Am only thinking of the possibilities and not dissuading you from pursuing your experiment..

Hope they had used 3 x 3.5mm to dual RCA to split the outputs as 6 different inputs to stereo amplifier..

Without a dedicated LFE out (Pre-amp out), movie experience would be limited, IMO..But in your case, i think it is not LFE out, but Analogue out..This would be critical part for movie experience?

Does your soundcard have any settings for LFE..

Also level matching speakers (75db SPL) is important from your listening position, which you could do it with external SPL meter.. I believe this will be a challenge as you are using stereo amplifier..If you increase volume to match level for a speaker, it will also proportionately increase the volume of the other speaker connected..
 

sdk

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Hi,

This is a fine way of running a future proof home theatre setup. I used to run my setup with 3 Cosmic amps and a bunch of full range towers and bookshelves for years. A little tweaking with volume, tone and balance controls will give you a very pleasing and balanced surround effect. I also used a 12" active sub with this setup. You can also do room correction via the Realtek software. The only disadvantage was that i could not play DTS music via this setup.

I would recommend the Norge Concerto Gold 1000 amps instead of any of the other models that they have. I also prefer their 8 ohm models of speakers rather than 4 ohms ones. This way it gives you flexibility to connect them to other amps too.
 

Amarendra

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Thanks sdk, I won't be using norge speakers. My speakers would be as follows:
Fronts: wharfedale 220
Center: wharfedale 220c
Rear: wharfedale 210
Sub: wharfedale d10
 

shibashis

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If this is a path you are considering perhaps it is prudent to incorporate a quality sound card on your PC, either internal or USB.

I have thought of something similar but I would go with an old non-HDMI receiver which you can get for cheap and feed the output from PC/Sound card to the 5.1 or 7.1 input of the receiver. Let the PC side handle all the processing and mixing and the amp can do its job of just pure amplification. A better solution in my opinion, cost-effective as well I would assume.
 
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