I need a high end amp for home theatre/music - diyAudio
Go Back   Home > Forums > Amplifiers > Solid State

Solid State Talk all about solid state amplification.

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 27th February 2003, 12:08 PM   #1
diyAudio Member
 
Join Date: Nov 2002
Location: Bangalore, India
Default I need a high end amp for home theatre/music

Hello,

I plan to build bi-amped two way speakers(for home theatre as well as stereo music). Towards that I am looking at using TDA7294 based design. Can anyone throw some light on the sonic abilities of this chip. Or can anyone suggest me a better amp. I have dropped TDA1514, since somewhere i read the quality is not too good. Since I will have to make 10 amps(For 5 channels), I would not like to go for discrete design. My preference in music is pop/rock but as I said I will also use the amp for Dolby Digital/DTS in home theatre setup. I am not looking for high power but a high end amp. Tweeter would be 8 ohms and Woofer would be 4 ohms(two 2 ohm units in series).

Thanks in advance.
__________________
Audio enthusiast/hobbyist
  Reply With Quote
Old 27th February 2003, 12:24 PM   #2
sangram is offline sangram  India
diyAudio Member
 
Join Date: Sep 2002
Location: India
7294 is not high end. No Way. Nada. Good, solid sound, very very good, but not high end. I myself love the sound of the chips but since I cannot get BG/FC, Vishays etc, I find discrete designs outperform the chipamps.

Some people have good experience with gainclones - LM 3875 based but I also hear the 7294 is at least as good as the LM 3875. That is pure hearsay, look up the board for both those chips.

And for non-discrete design, these are about as good as it gets. However you might have a bit of a nightmare with the chassis, PSU, etc. How are you planning to put all of it together? As one amp, or multiple chassis feeding off one preamp?

That said, you can look at a 7294 for the woofer and a lower powered amp for the mid/high units (or high, if you're planning two-way) - 20 watts from an LM 3875 or TDA 2040 should be good... Even a set of smaller discrete amps may be the ticket here.

Even if you look at a 70 watts per channel x 5 channel, that is about 350 watts of biamped power - as per estimates that should be as good as 700 watts of regular power, as someone may have you believe. You will need about 1 kilowatt of power to run the darned thing. And airconditioning - you will be losing quite a few watts as heat. Transformers? How are you going to configure the setup?

Maybe you can look at smaller, more efficient amps for surround channels? You will by this approach get a powerful but not high end system - the opposite of your design goal...

Unless, of course you look at things like Peter Daniel's Gainclone. I have a feeling the actual chip is the lowest-cost component of the whole system.
  Reply With Quote
Old 4th March 2003, 12:34 PM   #3
diyAudio Member
 
Join Date: Nov 2002
Location: Bangalore, India
Default Clarifications provided

Initially I will go for main speakers and main amps. Later I would repeat the same for centre and rear sets. All the speakers would be biamped with identical drivers.
I do not intend to go for different amps for main speakers and surround because of the sonic differences between different amps. Same goes for different amps for tweeeter/woofer. If it is 7294 for the woofer, it has to be another 7294 for the tweeter. The amps are going to be in speaker boxes so each box will have its independent power supply. What is 'Peter Daniel's Gainclone'. Is it some kind of reference. Please provide me suitable links. I am probably looking at drivers from peerless or high end monitor drivers from partsexpress (They have a low cost high end monitor kit). I probably will be using same drivers and not the whole kit
__________________
Audio enthusiast/hobbyist
  Reply With Quote
Old 5th March 2003, 05:14 AM   #4
sangram is offline sangram  India
diyAudio Member
 
Join Date: Sep 2002
Location: India
Look on the board for a post called 'This is not just another gainclone', started by Peter Daniel...
  Reply With Quote
Old 5th March 2003, 06:15 AM   #5
argo is offline argo  Estonia
diyAudio Member
 
Join Date: Feb 2001
Location: Estonia
I have tried both chips - LM3875 and TDA7293 (higher voltage brother of 7294)- LM inverted, TDA non-inverted.
Whether amps based on these chips qualify for hi-end or not, depends on multitude of variables, like passive parts used, power supply capacity, chassis construction etc and ultimately how much time and money you have spent on them.
But seriously, sound of some correctly made chip amps can be as good as of some discrete amps and certainly enough for Home Theatre. For HT I would prefer 7294 or 7293 because of their higher power output and more solid overall performance. For sub you can even bridge two chips. As you planning to put the amps in speaker boxes and this means long interconnects between amps and preamp, I wouldn’t recommend inverted topology.

argo
  Reply With Quote
Old 5th March 2003, 12:36 PM   #6
sangram is offline sangram  India
diyAudio Member
 
Join Date: Sep 2002
Location: India
Quote:
Originally posted by argo
As you planning to put the amps in speaker boxes and this means long interconnects between amps and preamp, I wouldn’t recommend inverted topology.

Good point.
Quote:
Originally posted by goldyrathore
I do not intend to go for different amps for main speakers and surround because of the sonic differences between different amps. Same goes for different amps for tweeeter/woofer. If it is 7294 for the woofer, it has to be another 7294 for the tweeter.
Just be careful of the volume you put into a tweeter, you will have to attenuate it to about 50% or so from the woofer volume, and that itself will somewhat change the sonic character of the amp - at a given volume, the woofer 7294 wil be working harder and the tweeter will be more relaxed, so there will be a sonic difference there too, though I concede, not as much as between different ICs, or between IC and discrete...

The 7294 is a very tough amp, as long as you ensure you heatsink it well, and play safe - the temptation of using 4 ohms at +-35 volt rails is high, and in my case, has resulted in the death of one of my chips.

I am now using one of them in a small homebrewed practice amp for my bass guitarist, and it gets into the act admirably, and is able to deliver tons and tons of low, deep bass without even getting warm... Highly recommended. I have not tried the 3875, but the 1875 is an amazing little beast. Sonically almost as good as a 7294, but only if you're not pushing the chip too hard...
  Reply With Quote
Old 6th March 2003, 12:33 PM   #7
diyAudio Member
 
Join Date: Nov 2002
Location: Bangalore, India
Default Different volume levels can be tackled

Hi Sangram,

Since I am going to use 8 ohm tweeter and 4 ohms woofer the volume of both the amps should be same in theory. In practice they would be different due to the higher sensitivity(typically tweeters have higher sensitivity than woofers) of the tweeter. I think that can be solved by having a parallel resistor with the tweeter. That would also damp the tweeter's impedance curve. There are no passive crossovers where the resistor can interfere with. I know there is no use having more power and then wasting in a resistor.
I agree, all this suggests that a lower power amp should be used for the tweeter but I really can't experiment with all combination of amps to find which amps sonically mate well. My method is more predictable. Kindly give suggestions.
__________________
Audio enthusiast/hobbyist
  Reply With Quote
Old 6th March 2003, 06:59 PM   #8
Pan is offline Pan  Sweden
diyAudio Member
 
Join Date: Sep 2002
gold,

a paralell resistor will not attenuate the tweeter without a series resistor.

You will flatten the impedance curve though, but better would be a dual resistor voltage divider.

/Peter
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
New Home Theatre Sub dark_avenger Subwoofers 11 29th December 2007 02:28 AM
DIY Home Theatre luckybob Multi-Way 4 25th May 2006 06:19 AM
Home Theatre bhg41088 Multi-Way 4 16th August 2004 01:32 PM


New To Site? Need Help?

All times are GMT. The time now is 02:48 PM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright ©1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2