Amp Upgrade

[simonsamp]

Hi folks,

I'm new here so apologies up front if I'm asking something obvious or stupid. Also feel free to direct me at the right part of the site to answer my stupid question ;-)

I currently own a Sony DAV-S800 home theatre system. This is a 5.1 system with satellite speakers rated at 50w and 6 ohm impedance (it doesn't have a 4/8 ohm switch like some amplifiers). Unfortunately, the output from the DAV-S800 for the front left speaker has stopped working. Reading around on the internet, this seems to be a common problem for which there is no real cure. I've had the system for just over four years; when I purchased it (for over £800 from an official Sony Centre) I took out an extended warranty of 3 years, to take the total warranty period to four years. So it's just out of warranty (a couple of weeks) but it won't be covered. This is why I need to buy a new AV receiver. As a small blessing, the speaker problem was also how I discovered this site, so sometimes good can come from bad.

I don't need the inbuilt DVD player of the DAV-S800 any more - nowadays I watch all my films via an xbox running Xbox Media Centre, using component output to my 43" Toshiba RPTV and optical audio output via a Toslink cable to the DAV. So basically I need a new AV receiver, ideally with a built in radio tuner (DAB digital if possible). I also have a Sky+ box and a Dreambox, both of which have optical sound output, and an SVHS vcr which has analogue sound output. So these are the devices I need to switch between.

The decoder I've been looking at is the Pioneer VSX-915S, available for £233.90 from http://www.digico.co.uk/default.asp?Detail=Yes&ModelID=703 (price includes delivery to my door). It has three optical inputs (unfortunately one of them is at the front, but it's in a cabinet anyway so not that noticable). It can also feed through component video, which may be nice. I'm thinking I could plug the Sky+, Dreambox and Xbox all into the Pioneer and have a single connection to the TV, then use the Pioneer to switch inputs. Not ideal, because I'd actually be sending RGB signals through and into a Scart input on the TV rather than the component connection (as the Sky+ box and Dreambox don't have component out), but I could live with the Xbox via RGB instead of component if I had to. Ideally it would upmix the RGB signal to a component video signal, but I guess it doesn't (is there anything that does?).

The Pioneer has 7.1 sound, which I guess I will want in future and therefore want to purchase now. The real question (apart from can someone recommend a better decoder in the same kind of price bracket) is to do with the speakers. I have cabled up the speakers for the existing 5.1 system while renovating the room. The wires are all hidden in the walls, and come out at exactly the right points for wall mounting the speakers, which are on brackets (I'm not using the floor stands that come with the DAV-S800) at exactly the right height on the walls. The four surround speakers are in the four corners of the room, and the centre speaker is in the middle of the front wall, above the Television. When wiring up the room, I also left two loose cables in the ceiling at around 40% of the side walls (nearer the rear), with the thought that if they ever come up with a 7.1 specification then I'll have cables ready for side speakers (probably in the ceiling).

So, my questions are as follows:

1) Can I use the 7.1 decoder as a 5.1 system for now, rather than purchasing and installing two extra speakers to make it 7.1?

2) The Pioneer has outputs rated at 100W and 8 ohms. Will this work with my 50W 6 ohm speakers?

3) Is the amp I'm suggesting a reasonable proposition? Or is there something similar for cheaper, or better for the same money?

4) Did anyone ever work out how to fix the DAV-SX00 left speaker problem (meaning that I don't have to upgrade yet)?

Thanks muchly for any help you can offer ;-)

-simon

 

[simonsamp]

Aha, one more thing - the DAVS-800 has a passive subwoofer. That will still work fine with the Pioneer, right?

Cheers,

-simon

 

[Buckle-meister]

...can someone recommend a better decoder in the same kind of price bracket...

I had a quick look at the specification for the Pioneer (nice piece of kit). It appears to have the full compliment of decoders. You wont find 'better' decoders on another machine; they are all standard Dolby Digital or Dts decoders which the Receiver manufacturers build into their products.

When wiring up the room, I also left two loose cables in the ceiling at around 40% of the side walls (nearer the rear), with the thought that if they ever come up with a 7.1 specification then I'll have cables ready for side speakers.

The difference between 5.1 and 7.1 is, as you know, two additional speakers. However, these 'surround-back' speakers are not placed at the sides where you indicate that you have spare runs of cabling. They are placed directly behind you, spaced slightly apart.

Can I use the 7.1 decoder as a 5.1 system for now, rather than purchasing and installing two extra speakers to make it 7.1?

Yes, this will not be a problem. Your Receiver will 'know' that you do not have the additional speakers connected and only offer you 5.1 sound. If in the future you do buy additional speakers, simply connect them up, re-calibrate, and the Reciever will offer you 7.1 sound.

The Pioneer has outputs rated at 100W and 8 ohms. Will this work with my 50W 6 ohm speakers?

I suspect so, but there are others here that are better placed to tell you one way or the other. If your speakers had been 50W 8ohm speakers, then they would definitely be ok (so long as you didn't crank your Receiver all the way up). As it stands, because they are 6ohm speakers, they are slightly more difficult to drive. But, like I said, I suspect your Receivers 100-50=50W spare capacity would be adequate.

Is the amp I'm suggesting a reasonable proposition? Or is there something similar for cheaper, or better for the same money?

Again, others will be more able to advise you on this than I. The Pioneer certainly appears to me to be ok, but I believe that Yamaha and Denon Receivers currently compete for the top spot in terms of value for money etc.

...the DAVS-800 has a passive subwoofer. That will still work fine with the Pioneer, right?

This I am not sure about. I had a quick surf, and found this showing the back (I believe) of your unit. I'm not familiar with that type of connection for a speaker. Hopefully others can clarify.

Welcome to the Forum neighbour!

Regards

 

[jaxvon]

The Pioneer is designed for use with a powered subwoofer. I'm not sure, but I think you might be able to loop the sub-out on your pioneer to an unused input (like surround back right) and use the corresponding unused amp to drive the subwoofer. Subs tend to need more power than normal speakers though, so I'm not sure that, even if this would work, how well it would perform.

 

[jcPanny]

Video conversion

Concerning your video questions, several receiver models that are slightly more expensive than the Pioneer 915 have a video conversion feature where they will take an input component, svideo, or composite video and output over a single component video cable. This conversion will not improve the quality of the video signal, but it will allow a single connection to the video display.

My Yamaha HTR-5860 is a great receiver in the $300+ price range and it has the video conversion feature.

 

[bobwood]

Don't worry about the wattage

The difference between 50 and watts is negligible. More speakers are blown out by distortion caused by underpowered amps than overpowered ones. Also the 6 ohm rating is an average. Shouldn't be a problem in any way for the amp you propose or the speakers you have.

It appears that your passive sub will also require new amplification. Most receivers don't do this, and if you use one of the rear (unused outputs) to feed it, you'll lose whatever bass control you might have (depending on which receiver you end up with.)

Hope this helps some.

Bob Wood
www.GreatHomeTheatre.com
www.woodsgoods2.blogspot.com

 

[mulester7]

The difference between 50 and watts is negligible. More speakers are blown out by distortion caused by underpowered amps than overpowered ones. Also the 6 ohm rating is an average. Shouldn't be a problem in any way for the amp you propose or the speakers you have.

It appears that your passive sub will also require new amplification. Most receivers don't do this, and if you use one of the rear (unused outputs) to feed it, you'll lose whatever bass control you might have (depending on which receiver you end up with.)

Hope this helps some.

Bob Wood
www.GreatHomeTheatre.com
www.woodsgoods2.blogspot.com

.....BobWood, the shame here, is that you have only posted 6 times.....

 

[mtrycrafts]

The difference between 50 and watts is negligible. More speakers are blown out by distortion caused by underpowered amps than overpowered ones. Also the 6 ohm rating is an average. Shouldn't be a problem in any way for the amp you propose or the speakers you have.

It appears that your passive sub will also require new amplification. Most receivers don't do this, and if you use one of the rear (unused outputs) to feed it, you'll lose whatever bass control you might have (depending on which receiver you end up with.)

Hope this helps some.

Bob Wood]

Tweeters are blown by too much power to them when an amp is driven into serious clipping. Clipping causes odd harmonics extending into the tweeters frequency range and the power of these harmonics is well beyond the tweeter's capability.

 

[mulester7]

Tweeters are blown by too much power to them when an amp is driven into serious clipping. Clipping causes odd harmonics extending into the tweeters frequency range and the power of these harmonics is well beyond the tweeter's capability.

.....interesting....very....aren't these proposed odd harmonics just another name for distortion?....so, the tweeter doesn't fry from too much "clean" power, but from odd harmonics, ok.....does that include radical pistonic movement in larger coned elements?....suspect it does.....

.....operation in the morning at 7 central....thoughts solicited.....

.....am I the only one, or did the issue here boil down to not enough watts-continuous?....watts that don't have to cost you tons....offer stands for the first return.....

 

[MDS]

Too many watts and you'll blow the tweeters too - even if there is zero distortion.

People tend to get carried away with the 'more speakers have been blown by too little power than too much' mantra. Go ahead and feed 200 wpc of clean power to your typical tweeter that can handle about 30 watts and see what happens...

 

[mtrycrafts]

.....interesting....very....aren't these proposed odd harmonics just another name for distortion?....so, the tweeter doesn't fry from too much "clean" power, but from odd harmonics, ok.....does that include radical pistonic movement in larger coned elements?....suspect it does.....

.....operation in the morning at 7 central....thoughts solicited.....

.....am I the only one, or did the issue here boil down to not enough watts-continuous?....watts that don't have to cost you tons....offer stands for the first return.....

Actually, it is not the distortion. How would the tweeter know a clean signal from a distorted one? Is it intelligent all of a sudden?

No, it is the power in those harmonics that kills the tweeter, period. At clipping, the RMS power increases to the level of peak power of the amp. After all, music is full of harmonics of all kinds, even and odd.

 

[mtrycrafts]

Go ahead and feed 200 wpc of clean power to your typical tweeter that can handle about 30 watts and see what happens...

LOL I think Smokey the Bear time there.

How would the tweeter know the difference between a clean signal and a distorted signal with power not exceeding the tweeter? If human doesn't listen and tells all it is distorted, the tweeter will not care. It is a signal of some kind. It doesn't care if it doesn't sound right

 

[mulester7]

Actually, it is not the distortion. How would the tweeter know a clean signal from a distorted one? Is it intelligent all of a sudden?

No, it is the power in those harmonics that kills the tweeter, period. At clipping, the RMS power increases to the level of peak power of the amp. After all, music is full of harmonics of all kinds, even and odd.

....then why will a 50 watt amp cranked to continuous clipping burn up 100 watt speakers?....it wasn't the power, it was the voice-coil.....