4 Ohm Speakers/Reciever Combo

[Jeff R.]

I am shopping for a new reciever and currently have all MB Quart speakers. I currently have a Harmon Kardon AVR-7000 which is a true work horse. My issue is that my front towers are 4 Ohm (QLS1030) towers and the center and rears are 6 Ohm speakers. I have looked at the ONKYO TX-SR806 and the Denon AVR-988. The issue is that Denon does not recommend using the 988 with a 4 ohm load and the SR806 has an option to place the amps into a 4 ohm selection, however is forces all channels to go to a 4 ohm output. Does anybody have any recommendations?

Thanks

Jeff

 

[3db]

I am shopping for a new reciever and currently have all MB Quart speakers. I currently have a Harmon Kardon AVR-7000 which is a true work horse. My issue is that my front towers are 4 Ohm (QLS1030) towers and the center and rears are 6 Ohm speakers. I have looked at the ONKYO TX-SR806 and the Denon AVR-988. The issue is that Denon does not recommend using the 988 with a 4 ohm load and the SR806 has an option to place the amps into a 4 ohm selection, however is forces all channels to go to a 4 ohm output. Does anybody have any recommendations?

Thanks

Jeff

If you are a minimalist and just require decodong of all the latest codecs, NAD would drive your Quarts just fine. NAD are 4 ohm stable receivers

 

[fmw]

When you say an amplifier is not 4 ohm stable, what you mean is that it is not 4 ohm stable at full output power. There is some power level below full output in which the amp can deal with a lower impedance. The little 4 ohm switch to which you refer simply reduces the maximum output power of the amplifiers to some leve that is stable at 4 ohms. The volume control can do the same thing.

Reality is that we don't use our amplifiers at full output power so almost all of them are 4 ohm stable at the levels we actually use. It is one of the reasons most home audio amplifiers are over powered for the application.

My own receiver has no power rating below 6 ohms but I've heard it drive a speaker system with impedances that dropped below 2 ohms at what I would consider loud levels - not full power, however.

Basically, a receiver is not built to do low impedances at full power. At what power will they do low impedances? Your guess is as good as mine. If you are concerned about it, then you should replace the receiver amplifiers with outboard amplifiers designed for low impedance work.

 

[phlakvest]

The onkyo 805 is certified to run at 4ohm. I'm driving 5 emotiva 4ohm speakers with mine.
I don't know how the amp in the 806 compairs in the beefyness department.

The 4ohm switch is a safety/marketing feature. I leave mine on the 6-8 ohm setting. There's a thread around here somewhere that explains the 4ohm switch. Ill try to find it.


http://www.audioholics.com/buying-guides/how-to-shop/av-receivers-buying-guide#impedance_selector

Impedance Selector Switches
This so called feature, used by some manufacturers, is designed to prevent overheating of the receiver or damage to its output transistors because of excessive current flow. The manufacturer accomplishes this in one of 2 ways: 1) Stepping down rail voltage supplied to the power amp or 2) feeding half the signal strength to a voltage divider of power resistors. Both of these methods severely limit dynamics and current capability of the power amp. This results in an audible decrease in bass capability and dynamics transient sound because the 4 ohm setting effectively increases the receiver's output impedance. Unfortunately many manufacturers put these features on their products to ease customer concerns with driving low impedance loads and for safety reasons when getting UL approvals. Note: In order to meet UL requirements, a receiver cannot be rated down to 4 ohms without having this switch onboard. Receivers without this switch are usually rated down to 6 ohms. In most cases, well designed receivers can easily handle 4 ohm loads safely and efficiently. It is highly recommend to keep the impedance switch set to 8 ohms regardless of your speakers impedance and make sure your receiver has plenty of ventilation.

What's the sensitivity on your speakers?

 

[TLS Guy]

I am shopping for a new reciever and currently have all MB Quart speakers. I currently have a Harmon Kardon AVR-7000 which is a true work horse. My issue is that my front towers are 4 Ohm (QLS1030) towers and the center and rears are 6 Ohm speakers. I have looked at the ONKYO TX-SR806 and the Denon AVR-988. The issue is that Denon does not recommend using the 988 with a 4 ohm load and the SR806 has an option to place the amps into a 4 ohm selection, however is forces all channels to go to a 4 ohm output. Does anybody have any recommendations?

Thanks

Jeff

FMW has given you some good advice. It really does depend on how hard you want to push things, to the limit or not.

The reality is that the Onkyo receiver will likely deliver half its rated power into four ohms, and if you push it, you might damage it. Remember however the difference between half power and full power is only 3db.

The problem is compounded by the fact that speakers are all over the map, and certainly I have encountered speakers that do require hefty power, the B & W 800D for one, many Dynaudio and I have to say a few of my own designs.

It has recently been proposed that speakers have an amplifier stress index, which would account for the phase problems and express equivalent impedance against frequency. Then people would have a better idea, how to judge the amplifier power required.

This topic came up recently and surfaces all the time. Here is a recent post of mine discussing the issues.

I wish there was a simple one fits all answer to your question, but there isn't, so the more you understand the issues the better.

 

[Jeff R.]

Phlakfest - Thanks - My speakers at 87 dB sensitivity. They are rather large towers if you are not familiar. They are a 4 way speaker design with tweeter, 4" and dual 6.5"s. I am pretty sure that I am going to go with the Onkyo Reciever. I am just trying to get some extra opinions on the issue.

Anybody else have some other recommendations for a reciever? I am trying to keep it under $1000.00 I actually have found the Onkyo marked down online as low as $620 which is why I am leaning toward it currently.

 

[mtrycrafts]

Phlakfest - Thanks - My speakers at 87 dB sensitivity. ...

Don't forget, the sensitivity rating on a spec sheet is for anechoic chamber condition, unless they say in room. If not, you can add 4 dB to that sensitivity for in room conditions.

 

[TLS Guy]

Phlakfest - Thanks - My speakers at 87 dB sensitivity. They are rather large towers if you are not familiar. They are a 4 way speaker design with tweeter, 4" and dual 6.5"s. I am pretty sure that I am going to go with the Onkyo Reciever. I am just trying to get some extra opinions on the issue.

Anybody else have some other recommendations for a reciever? I am trying to keep it under $1000.00 I actually have found the Onkyo marked down online as low as $620 which is why I am leaning toward it currently.

Before you buy, I would contact MB Quart and see if you can get an impedance curve out of them at least. A voltage current phase curve would also be very nice. Does it quote a minimum impedance in the literature that came with the speaker? I could find no useful information about them on their website. However a speaker configured like that is just the sort of speaker that could well present a very difficult load to an amplifier. There are a lot of drivers and multiple crossover points. It is just those sort of designs that are prone to produce the worst amplifier stress.

I would make good and sure those speakers don't cruise along at an effective two ohm impedance for a good chunk of the frequency spectrum.

 

[phlakvest]

What kind of volume are you trying to achieve?

Have you considered the 805 as opposed to the 806? http://forums.audioholics.com/forums/showthread.php?t=49396

IMHO the 805 is a slightly higher quality reciever, not to mention it has a more powerfull amp section.

It would probably stand a better chance driving those speakers than the 806.

Also, have you considered a seperate amplifier?
You can get a yamaha 663 and an emotiva xpa5 for close to $1000

 

[Jeff R.]

I will have to revisit the 805, I assumed that these two recievers were essentially the same. However in reviewing the Onkyo web site it does appear that the 805 does have a more substantial amp. Which probably explains the difference in weight between the new and the old. Can you think of any limitation for future use that the 806 would give me? I have been out of the loop on things since about 8 years ago when I purchased all my gear, so I am just now getting back in to upgrade my reciever and sub and get a Blue Ray disc. (Any reason not to use the PS3 as my Blue Ray?)

 

[Seth=L]

I will have to revisit the 805, I assumed that these two recievers were essentially the same. However in reviewing the Onkyo web site it does appear that the 805 does have a more substantial amp. Which probably explains the difference in weight between the new and the old. Can you think of any limitation for future use that the 806 would give me? I have been out of the loop on things since about 8 years ago when I purchased all my gear, so I am just now getting back in to upgrade my reciever and sub and get a Blue Ray disc. (Any reason not to use the PS3 as my Blue Ray?)

The Onkyo TX-SR805 has almost all the features they newer TX-SR806 has, but it has more power. They both use the same principle amplifier topology, only the TX-SR805 has a 20 pound advantage in combat (it's a monster receiver at 50 pounds). You can also find the TX-SR805 for cheaper, which makes it perfect.

The TX-SR805 is definitely 4 ohm stable. THX Ultra standards require that the receiver be able to drive loads as low as 3.2 ohms at reference levels in large rooms, which means it will have more than enough power to drive those speakers to excruciating levels of output (the benchtests don't lie on this guy).

I have two PS3s, I see no reason not to use the PS3 as my Blu-ray player. It can decode all HD formats internally and produces stellar PQ with Blu-rays and DVDs alike. The upscaling benchtests for the PS3 with the latest firmware compare favorably to most stand alone upscaling DVD players in the same price bracket, and far exceeding that of Blu-ray player's upscaling abilities for DVD (being $400).

Also, don't use the 4 ohm setting. If you set the receiver to 4 ohms all it does is limit power supply output current, effectively protecting retards from blowing their equipment. Which is sorta silly considering what that receiver is capable of.

3dB, not to be a naysayer or anything. But I'd be surprised if anything that NAD offers in the same price range as the Onkyo TX-SR805 will come anywhere close to comparing in terms of the power capability the TX-SR805.

 

[wire]

I am shopping for a new reciever and currently have all MB Quart speakers. I currently have a Harmon Kardon AVR-7000 which is a true work horse. My issue is that my front towers are 4 Ohm (QLS1030) towers and the center and rears are 6 Ohm speakers. I have looked at the ONKYO TX-SR806 and the Denon AVR-988. The issue is that Denon does not recommend using the 988 with a 4 ohm load and the SR806 has an option to place the amps into a 4 ohm selection, however is forces all channels to go to a 4 ohm output. Does anybody have any recommendations?

Thanks

Jeff

Those are some power pigs . Be careful , you are the one who will be putting time and money into some new tweets , if you are not careful .
87db @ 4ohms thats a heavy load for almost any reciever .
A front 2 channel amp might be a option . I would check with the MB quart or whom ever you decide to go with for a reciever .
Most here don't have the quality of speaks you have here .

 

[Jeff R.]

wire

I have been running on a HK AVR 7000 for the last 9 years and punishing the crap out of the speakers and the reciever with no issues. The HK has similar amp ratings from a wattage rating and both are capable of drawing up to 60 A. I was hoping to basically match my existing output with the Onkyo and puck up all new fancy bells and whistles. What do you think? Are they relatively comparabe from an amp stand point....

Thanks

 

[jostenmeat]

Mini-hijack: 805 gives you

-XT version of MultiEQ (at least 8x the filtering rez of vanilla MEQ)
-Burrbrown DAC (same model used in the $7k Denon AVP)
-beefy Ultra rated isolated, push-pull amp

The 806 gets you Dyn EQ/Vol.

So if you can crank it whenever you want, or have an acoustically challenged room, go 805. If sharing walls w/ neighbors, or sleeping kids, go 806.

The PS3 is the only BDP that is a video gaming console. There is no comparison, if you use that. Its a fine player. Other players might be more convenient for particular audio setting/switching, and perform better in test shootouts.... but ... well... the PS3 is a special thing.

OTOH, you can always add a secondary standalone. My friends BD drive in his PS3 died after a year, but he used it for EVERYTHING...

edit: oh, btw, I own both Onkyo and NAD.

 

[zumbo]

The Quarts are Haaaaaard to drive. Choose wisely. I use an Adcom 7605 with my 830's, sending them 175w. I light-up the clip indicators every single time I crank it.

 

[TLS Guy]

The Quarts are Haaaaaard to drive. Choose wisely. I use an Adcom 7605 with my 830's, sending them 175w. I light-up the clip indicators every single time I crank it.

I was afraid of that!

 

[wire]

wire

I have been running on a HK AVR 7000 for the last 9 years and punishing the crap out of the speakers and the reciever with no issues. The HK has similar amp ratings from a wattage rating and both are capable of drawing up to 60 A. I was hoping to basically match my existing output with the Onkyo and puck up all new fancy bells and whistles. What do you think? Are they relatively comparabe from an amp stand point....

Thanks

From my knowledge , older HK stuff had great amp sections . I like a 2 channel amp for your front speaks
( like a used from audiogone.com something like this amp http://www.audiogon.com/cgi-bin/cls.pl?ampstran&1233107448&/NAD-270 , a amp like this is going to go down to 2 ohm load ) and your receiver taking care of the rest of the speaks .

 

[Midcow2]

I second the vote on the 805

I will have to revisit the 805, I assumed that these two recievers were essentially the same. However in reviewing the Onkyo web site it does appear that the 805 does have a more substantial amp. Which probably explains the difference in weight between the new and the old. Can you think of any limitation for future use that the 806 would give me? I have been out of the loop on things since about 8 years ago when I purchased all my gear, so I am just now getting back in to upgrade my reciever and sub and get a Blue Ray disc. (Any reason not to use the PS3 as my Blue Ray?)

I second the vote to get the 805 over the 806. The 805 is a very nice high current (4 ohms supported) AVR!

The PS3 makes a great BD player; And if your primary purpose is DVDs then Sony makes a traditional controller that is a little easier to navigate than the game controller. The PS3, because of its brute software/CPU powe,r is one of fastest loading , if not the fastest BD players.

Good Luck!

MidCow2

 

[Jeff R.]

Thanks for the advice. I just purchased the 805 last night. Got a killer deal on it direct from Onkyo as a Reburb ($435) I put the extra 2 years warranty on it for the $60 to give me a safety net. $495 total with free shipping. I will see how it goes.

If I have issues I will consider adding an extra 2 channel amp to assist. Can I use a lesser amp and use it and my reciever to Bi-Amp my speakers?

 

[wire]

Thanks for the advice. I just purchased the 805 last night. Got a killer deal on it direct from Onkyo as a Reburb ($435) I put the extra 2 years warranty on it for the $60 to give me a safety net. $495 total with free shipping. I will see how it goes.

If I have issues I will consider adding an extra 2 channel amp to assist. Can I use a lesser amp and use it and my reciever to Bi-Amp my speakers?

Congrats
Look @ this Amp also http://www.audiogon.com/cgi-bin/cls.pl?ampstran&1232390896&/Adcom-GFA-555-stereo-amplifier , good price on it .