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Old 19th February 2014, 16:09   #2086
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Default re: The Home Theater thread

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Originally Posted by NetfreakBombay View Post
... if AVR cannot power all channels to full power "concurrently", this should not have any impact, I.e. amplifier should not clip the audio.
'Clipping' is not the only impact. What Navin and ::CMS:: are pointing out is incorrect amplification resulting from power supply limitations - resulting in incorrect realism. The human ear is extremely sensitive and can detect infinitesimal differences. Whereas for some lack of realism is intolerable, for rest of us (and that includes me) ignorance is bliss till we get to feel the differences the first time!

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... Just a guess, each of these speakers might be capable of drawing 80 - 150 Watts at moderate loudness, it that in the right ballpark?) ...
Speakers don't "draw" power (they cannot on their own modify their own characteristics drawing less or more power) - power is "pushed" through them by the amp. That is where amp regulation, damping etc. are issues in being able to push the right amount of power at all times.

All speakers ratings, like Power, are "limitations" (not "desirable capabilities") declared by the manufacturer - beyond which either reproduction fidelity or component health is not guaranteed.
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Old 19th February 2014, 17:17   #2087
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Default re: The Home Theater thread

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Originally Posted by DerAlte View Post
pointing out is incorrect amplification resulting from power supply limitations - resulting in incorrect realism.
Can you mention that in technical terms? I.e. what can cause incorrect amplification even when AVR is being used within rated power consumption.

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Originally Posted by DerAlte View Post
Speakers don't "draw" power ..... - power is "pushed" through them by the amp. That is where amp regulation, damping etc. are issues in being able to push the right amount of power at all times.
I think that is not the case. Speaker models have different impedance curves.

Amount of current that flows through the audio cables+speaker will change depending on speaker. I.e. with

1. Same amplifier
2. Same input signal
3. Same volume setting in amplifier

Change in speaker will change impedance and thus will change amount of RMS power drawn.

Just like connecting a 10k ohm resister to a cell will draw very little power. But connecting a wire will draw enough power to cause a fire.

Last edited by NetfreakBombay : 19th February 2014 at 17:18.
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Old 19th February 2014, 17:54   #2088
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Default re: The Home Theater thread

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Originally Posted by NetfreakBombay View Post
Can you mention that in technical terms? I.e. what can cause incorrect amplification even when AVR is being used within rated power consumption. ...
* "being used within rated power consumption" is a simplistic assumption - you need decent instrumentation to prove this - it is a non-trivial issue. Think simultaneous peak demand by the FL & FR channels, with very low signal on, say, RR
* We are talking of different amplifiers working off of the same PS rail
* "Incorrect amplification": In instantaneous terms, current driven through the speaker depends, ultimately, on the power supply rail voltage (would need you to look at an amplifier circuit final stage to relate to this) - gain and speaker impedance are constant in this time window

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Originally Posted by NetfreakBombay View Post
... I think that is not the case. Speaker models have different impedance curves. ...
Alas, we are not talking of the same things here! Yes, it is all (almost) simple Ohm's law here, but you seem to be giving basic principles in electronic circuits a go-by!!!

EDIT: I think we are taking the thread away from it's intended direction of "Which ...?" to "How ...?" - we are severely OT here

Last edited by DerAlte : 19th February 2014 at 18:01.
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Old 19th February 2014, 18:11   #2089
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Default re: The Home Theater thread

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Originally Posted by DerAlte View Post
simultaneous peak demand by the FL & FR channels, with very low signal on, say, RR
That was the point of analysing Audio in BR discs. Sound recordings seem to ensure that not all channels peak at the same time.


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Originally Posted by DerAlte View Post
Alas, we are not talking of the same things here!
Sorry, did not get it. I think power-draw has a very specific technical meaning and it is a measurable quantity.

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Originally Posted by DerAlte View Post
you seem to be giving basic principles in electronic circuits a go-by!!!
Can you help me with an example of such principle in case of power draw?

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Originally Posted by DerAlte View Post
EDIT: I think we are taking the thread away from it's intended direction of "Which ...?" to "How ...?" - we are severely OT here
Forking this thread might help, if there is interest in the topic.
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Old 19th February 2014, 19:02   #2090
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Default re: The Home Theater thread

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Originally Posted by NetfreakBombay View Post
That was the point of analysing Audio in BR discs. Sound recordings seem to ensure that not all channels peak at the same time. ...
You are viewing information at a zoomed out level (minutes, hours). For this, you need to zoom in, say, to 10ms level (x axis units) - as close to analyzing an 'instant' as possible. The signals look different then.

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Originally Posted by NetfreakBombay View Post
... Can you help me with an example of such principle in case of power draw? ...
Elementary electrical principles!

One needs a voltage source to force a current through a passive element like a resistor or inductor. A capacitor can be a source or a passive component based on circuit and signal conditions. Passive elements don't have any control over how much current flows through them - the voltage source has to modulate that. A lamp cannot influence that - the external power source has to drive a current through it. A dimmer is a variable voltage source. The lamp will produce whatever light it can produce based on the voltage presented - that is why voltage fluctuation shows up as fluctuation of illumination.

Ditto for speakers. The voltage source, amp in this case, 'draws' power from the PSU, and - based on the signal demand - presents a variable voltage across the speaker, which causes proportional current to be 'pushed' through the speaker coil, which causes the voice coil to dance in the magnetic field of the speaker magnet, which moves the cone, which ... produces sound.

Now, if the PS rail voltage dips, less of current is forced through the speaker, producing a weaker sound, so on and so forth!
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Old 19th February 2014, 22:15   #2091
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Default re: The Home Theater thread

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Originally Posted by DerAlte View Post
You are viewing information at a zoomed out level (minutes, hours). For this, you need to zoom in, say, to 10ms level (x axis units) - as close to analyzing an 'instant' as possible. The signals look different then.
That pattern repeats at even most granular level, for example when a helicopter is flying sound "sweeps" across channels and it can clearly be seen in waveforms too.

One of the examples I posted was at second level, this is part of that zoomed in at microsecond level.

The Home Theater thread-dark_knight_catching_crane_ms.png

Quote:
Originally Posted by DerAlte View Post
Ditto for speakers. The voltage source, amp in this case, 'draws' power from the PSU, and - based on the signal demand - presents a variable voltage across the speaker, which causes proportional current to be 'pushed' through the speaker coil, which causes the voice coil to dance in the magnetic field of the speaker magnet, which moves the cone, which ... produces sound.

Now, if the PS rail voltage dips, less of current is forced through the speaker, producing a weaker sound, so on and so forth!
Thats why I said different speakers will "draw" different amount of current because of difference in impedance. Voltage (wave of voltage) that is produced by amplifier is governed by Signal and Volume knob and not by speakers.

If an Naveen's spakers are connected to an AVR those might draw more power if impedance is lower. That was my question to Navin, how much power is drawn by his speakers.
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Old 20th February 2014, 10:17   #2092
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Default re: The Home Theater thread

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Originally Posted by NetfreakBombay View Post
I am certain a 210 Watt AVR will be running for cover if paired with your custom speakers.

Such speakers are rated for 60 - 100 W each, and not all channels are driven at the same time by audio sources.
Thanks NetFreak, I have been doing this for almost 4 decades, every few years i get an itch to build something different. I am a sick old man. The bedroom speakers are very heavy so much so we needed a air cusion mobility system (I have imported one of these http://www.airsled.com/appliance.htm) to help me move the speakers around.

The power handling ability of a speaker has little bearing on the AVR. What is more important is the speaker's sensitivity (my living room speakers were tested in room to be in almost 90db/1W between 200Hz and 10khz, single channel driven), the woofer's Xmax (in a HT it is the subwoofer), and the speaker's response in room (which is why the room is such an integral part of the system).

Since speaker's impedance (reactive and resistive components of a speaker) varies over it's frequency range the ability of an AVR to deliver consisent power into varying impedances is more important. A simple 2 way bass reflex speaker's imepdance may vary from as high as 20 ohms at port resonance to as low as 3-4 ohms in Fb and around the crossover frequnecy. see image in link below
http://www.claudionegro.com/sw/swimp...diffusore1.jpg

Now there are methods that allow one to flatten the impedance and make it more resistive (hence more efficient) which is what I have done. Some are common such as RC networks in parallel with the tweeter to flatten out the rising impedance due to the inductive nature of the a tweeter's voice coil, others are more complex such as LCR traps and LR tanks; the later are also used for baffle step compensation. As crossovers get more complex they also become more expensive but again we digress.

Coming back to the issue on hand, with low power AVRs it makes more sense to get speakers of moderate sensitivity (we can/will get to the realtion between sensitivity and other parameters in a seperate discussion) say "87db-92db/1W from 200-10khz single channel in-room". Sadly few manufacturers specficy their sensivity rating accuately and all attempts to establish standards have failed.

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Originally Posted by ::CMS:: View Post
Yes, it does make a big difference.
Boy you got a lot of boxes! Maybe it's time to invest in a multi-channel power amp? I have a pair of 2-channel power amps that are rated to deliver 200W rms (1200VA R-core transformer, 120,000uf of stiffening caps, and the old Metal Can Hitachi MOSFETs). Each amp weighs about 34 kgs. Maybe you should build 5 channels. I can send over the schematic.

Last edited by navin : 20th February 2014 at 11:28.
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Old 20th February 2014, 15:00   #2093
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Default re: The Home Theater thread

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Maybe it's time to invest in a multi-channel power amp?
, yes lot of boxes, but all on a rack (like the way it looks on a rack). My setup is slightly different, its for both music and HT. I am using the same front speakers and power amp for 2 channel music and HT. Only the preamps are switched based on the requirement.

So for music :
Source (Music PC) >> 2Channel PreAmp >> PowerAmp >> FL/FR Speakers

and for HT:
Source (HTPC) >> HD Pre-Processor >> PowerAmp >> FL/FR Speakers + Onkyo 606 (Center channel), planning for a Monoblock later + Onkyo HT320 (surrounds)

so that, I get both the flavours of 2channel and Multichannel and I need to switch-on all the boxes only for HT (except the 2 channel pre). This is difficult to achieve in a single multi-channel amplifier. Moreover, I tried several multichannel amps, I am yet to hear a good one than my 2 channel poweramp, esp for music. Moreover, I am planning to TriAmp my FL/FR with PASS LAB's Class A F5 Turbo PowerAmps (only for music).

Following is the setup:

2Channel :

- MusicPC \ HTPC (MultiBoot)
- Yamamoto YDA01 DAC kit (http://www.6moons.com/audioreviews/yamamoto7/dac.html), Beresford Caiman DAC (till the other build is complete)
- Acoustic Portrait PM1 Tube PreAmp
- QUAD 909 PowerAmp
- ATC SCM40 speakers (http://www.stereophile.com/content/f...ment-59-page-2)

MultiChannel:

- Emotiva UMC-1 HD Pre-Processor
- Onkyo 606 amp (center ch) + Onkyo HT320 amp (surrounds)
- Behringer Feedback Destroyer Pro DSP 1124P (for my TappedHorn subwoofer)

All together 9 metal boxes and 2 more to come

Last edited by ::CMS:: : 20th February 2014 at 15:06.
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Old 21st February 2014, 13:53   #2094
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Default re: The Home Theater thread

Going a bit old style these days.
I need suggestion in getting a Vintage Nakamichi 680zx cassete deck.This will not be played everyday, but mostly once a week / month.
I am also looking to purchase a turntable.Is it okay if i go with belt drive rather than direct drive?
Can you guys please give me some inputs.Thank you.
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Old 21st February 2014, 14:11   #2095
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I need suggestion in getting a Vintage Nakamichi 680zx cassete deck.This will not be played everyday, but mostly once a week / month.
Few of these seem to be available on ebay in US :

http://www.vintagecassette.com/nakamichi/680zx/forsale
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Old 21st February 2014, 14:16   #2096
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Few of these seem to be available on ebay in US :

http://www.vintagecassette.com/nakamichi/680zx/forsale
I have one near my place, which I can actually see.The issue with EBAY, I dont know what I am purchasing.
Moreover the guy is asking an equivalent of INR 17600.
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Old 21st February 2014, 14:24   #2097
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I have one near my place, which I can actually see..
Yes, ebay is not useful in that case. You will have yo pay customs in addition to shipping.
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Old 21st February 2014, 14:55   #2098
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Vintage Nakamichi 680zx cassete deck
Its a good choice, provided the condition is good. If you can stretch a little bit, try their Dragon series with microprocessor controlled azimuth correction aka Nakamichi Automatic Azimuth Correction (NAAC) for the best sound reproduction or any RX range like RX505 or 1000Zxx series.

Quote:
belt drive rather than direct drive?
For an entry level TT, I prefer a Direct Drive over a belt drive. Once you go higher up better designed belt drives are there. Technics SL1200 is one example of a good direct drive TT. I am using a Technics Direct Drive TT, but in the process of revamping it with upgraded Tonearm and cartridge with solid plinth and similar design as islolated belt drive TTs.

Last edited by ::CMS:: : 21st February 2014 at 14:59.
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Old 21st February 2014, 20:02   #2099
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Originally Posted by NetfreakBombay View Post
Yes, ebay is not useful in that case. You will have yo pay customs in addition to shipping.
Yes,And after all the hassles,if I get a LEMON,I will be done for.

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Its a good choice, provided the condition is good. If you can stretch a little bit, try their Dragon series with microprocessor controlled azimuth correction aka Nakamichi Automatic Azimuth Correction (NAAC) for the best sound reproduction or any RX range like RX505 or 1000Zxx series.

For an entry level TT, I prefer a Direct Drive over a belt drive. Once you go higher up better designed belt drives are there. Technics SL1200 is one example of a good direct drive TT. I am using a Technics Direct Drive TT, but in the process of revamping it with upgraded Tonearm and cartridge with solid plinth and similar design as islolated belt drive TTs.
In the earlier section if you would have seen, I had a Dragon which I gifted to my dad, because he brought one among the first Nakamichis into the state in 75-76 ,I think and that was a Nakamichi 500 -Dual Tracer.He still has it along with a BX-2 and the Dragon.
Now since I dont have a deck and all the tapes are getting covered in dust -I was debating between, Nakamichi,Revox or Tandberg.The latter 2 are almost impossible to find other than in ebay.

Personally I prefer a direct drive fully automated over a Belt drive.It is sad Technics discontinued the 1200 in 2010 and I cant find any brand new ones anywhere.I have an option between a brand new,last decde built DUAL belt drive OR a brand new Denon DP29F also belt driven.Both costs the same.
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Old 21st February 2014, 22:02   #2100
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Default re: The Home Theater thread

Dear FMs,

So far I was quite happy with my Creative Inspire speakers, but I want to start building a budget home theater setup. I am a total novice in this and my knowledge is very limited. Initially, I am looking for an AVR and a pair of front speakers. Budget for both is Rs. 50,000/-. I am looking at an entry level AVR at ~Rs. 25,000/- and front speakers pair for ~Rs. 25,000 to 30,000/-. I want a 5.1 capable setup but initially I am going only for the fronts. Later on I may add a sub or center. While being ready for a 5.1 setup for some movies, the AVR will be primarily used for music and HDTV channels. Since, music is primary usage, I have shortlisted the below AVRs.

Marantz NR1403
Pioneer VSX-523-K
sony STR-DH540
Yamaha RX-V375

I am looking at either of the following speakers:
Wharfedale Diamond 10.2 bookshelves
Polk Audio TSX330T floorstanders

My music listening preferences are warm, groovy, deep, good sound stage, immersive, tight/deep bass but not booming. The system will be placed in living room which is L-shaped with dining hall, and where the system is, the hall is 15 x 10 sq ft. This is an apartment, hence roof-crashing loudness or floor shaking bass are not needed. Just an immersive music experience all around me. I like to sit and spend time in front of the system to listen to music and lose myself in the experience.

I haven't demoed any of the above given options - only collected literature about them. For musicality, I believe, Marantz and Yamaha will go well with Wharfedale. However, I am inclined towards the Pioneer VSX-523-K as this is said to be bright sound signature and will complement Wharfdale well.

My questions are:
1. Which above given AVR will match the given set of speakers, musically as well as power/ohms specifications? (Especially, VSX-523-K which has higher wattage pairing with Wharfedale having less)
2. Will Polk TSX330T floorstander better than Wharfedale musically speaking?
3. Where in Chennai can I demo/buy these equipment?

Thanks,
murillo.
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