Ohm question, maybe a problem

[pewternhrata]

i have an onkyo TX-SR603X receiver, just bought a pair of martin logan montage (yes they are awesome, and sound amaizing with my B&W lcr600s3) first problem i guess is that i am underpowering these now, but mostly concerned about the 5ohm load for the logans and what my manual for onkyo says about not to use speakers under 6ohms or the auto protect may be enabled, is there anything to do about this? or is the onkyo just not gonna cut it with the logans? havent had a problem yet and everything sounds great but i also havent got a chance to sit down and watch a full movie with them yet.

 

[MDS]

It could be a problem at high volume levels, especially if those 5 ohm nominal speakers dip well below 5 ohms. But if the receiver doesn't go into auto-protect mode and shutdown or get excruciatingly hot at your normal listening levels then it will be ok. However, for low impedance hard to drive speakers you really should consider an external amp as that is one case where an external amp surely will make a difference.

 

[Seth=L]

You may be fine at lower volumes, but I would suggest upgrading the AVR soon. Have you looked at the Onkyo TX-SR805. It is a very good deal for a new receiver and can handle 4 ohm loads.

You could also try one of these.

http://www.ecost.com/detail.aspx?edp=37273512

It is older, but one solid machine. This receiver has pretty much everything you would need aside from HDMI features but has the amplifier heft to handle more difficult speakers like the Montage. The heft of this receiver alone is a pretty good indication of what it is packing. I have the RX-DP9 which is very similar (older and less features) and I love it. The RX-DP20 was JVC's flagship and probably one of the best receivers they came out with in the past 10 years maybe ever.

 

[pewternhrata]

alright this whole part is gonna be new to me, what all is involved in hooking up and setting up an external amp? brands to look for? as well as cost?

 

[Seth=L]

It could be a problem at high volume levels, especially if those 5 ohm nominal speakers dip well below 5 ohms. But if the receiver doesn't go into auto-protect mode and shutdown or get excruciatingly hot at your normal listening levels then it will be ok. However, for low impedance hard to drive speakers you really should consider an external amp as that is one case where an external amp surely will make a difference.

The TX-SR603 does not feature preouts to support an external amplifier.

 

[MDS]

The TX-SR603 does not feature preouts to support an external amplifier.

That's right and I should know better. Onkyo doesn't include pre-outs until the 7xxx models.

 

[pewternhrata]

alright well something for me to start looking onto, how much am i looking at having to spend to get a decent receiver that can power these? is around 800 gonna cut it? and of course cheaper is better haha, gonna run by the dealer tomorrow after work tomorrow and see if maybe he can work with me on something

 

[Seth=L]

alright well something for me to start looking onto, how much am i looking at having to spend to get a decent receiver that can power these? is around 800 gonna cut it? and of course cheaper is better haha, gonna run by the dealer tomorrow after work tomorrow and see if maybe he can work with me on something

If you need power I would look no further than that JVC, if you need power and the latest features you will be spending at least double that. It will take at least $800 to get the same power as the JVC. And make no mistake, the JVC is loaded with features you would likely never use.

 

[pewternhrata]

also just a side note to clarify for myself, i listen to music as well as watch movies, does that play any role in the receiver i pick out or what to look for?

 

[fmw]

I would just play the system. If the receiver goes into protection mode, then I would do something about it right away. If it doesn't, then enjoy. Reasonable volume levels, good heat dissipation and design tolerances in the receiver should allow everything to work OK. If not, then you will know there is a problem well before we do. Enjoy the new gear.

 

[jcPanny]

Receiver options

alright well something for me to start looking onto, how much am i looking at having to spend to get a decent receiver that can power these? is around 800 gonna cut it? and of course cheaper is better haha, gonna run by the dealer tomorrow after work tomorrow and see if maybe he can work with me on something

Yes, the Onkyo 805 is in the $800 price range. It is a 50 lb receiver with a very good amp stage and should be much more capable of driving the logans.

Another option would be a less expensive receiver with pre-amp outputs and a stereo amp for the mains.

 

[Seth=L]

also just a side note to clarify for myself, i listen to music as well as watch movies, does that play any role in the receiver i pick out or what to look for?

For music at what level of output? If you don't listen to music very loud it may not be a major concern. But if you like to take it to the limit at times a 50 pound receiver like the Onkyo TX-SR805 or the JVC RX-DP20 are going to sound better at higher levels. Things you will notice is less dynamic compression at the top and bottom ends.

When I used an Onkyo TX-SR502 to power a pair of PSB floorstanding speakers it was evident that the receiver was loosing power when I took it to higher levels of output (in a small room in an apartment). It also depends on the space you are trying to fill. If you have a medium to larger size room a receiver upgrade is likely to be a good idea to keep the speakers controlled for high output situations.

Just curious, does no one agree that the JVC RX-DP20 for $340 + approximately $30-40 for shipping is a good option for someone that may not need HDMI in the immediate future? It seems as though it is being ignored. Would their be a reason why it would not work well for this application? It is 4 ohm rated and I would class it as matching or very near to the Onkyo TX-SR805 in terms of amplification for a fraction of the price.

 

[pewternhrata]

was able to stop up at the dealer after work today and talked to him, he said the onkyo i have should not have a problem with the 1ohm difference, looked around at some rotel's and i liked them a lot, he also said there wouldnt be too too much of a difference all around between a mid priced denon and my current onkyo ( i know i know he just wants me to buy a 1400 rotel from him lol ) seems like he was basically saying i have a decent receiver to run them for now and when i want to upgrade i should look into something in the higher end audio, which is what i was planning on doing sometime in the next couple months. any opinions if i should get an all around receiver or try getting into the seperates with a processor and external amp?

 

[Seth=L]

was able to stop up at the dealer after work today and talked to him, he said the onkyo i have should not have a problem with the 1ohm difference, looked around at some rotel's and i liked them a lot, he also said there wouldnt be too too much of a difference all around between a mid priced denon and my current onkyo ( i know i know he just wants me to buy a 1400 rotel from him lol ) seems like he was basically saying i have a decent receiver to run them for now and when i want to upgrade i should look into something in the higher end audio, which is what i was planning on doing sometime in the next couple months. any opinions if i should get an all around receiver or try getting into the seperates with a processor and external amp?

The Rotel would offer no significant advantage over the Onkyo TX-SR805, and the TX-SR805 definitely has an advantage over the TX-SR603 in terms of power. Remember than 5 ohms is a nominal impedance rating, it will go higher or lower depending on the frequencies it plays, 5 ohms is just an average.

 

[pewternhrata]

so ive decided my budget is closer to 1k, just soo much out their and def. need something for that 5ohm load, but also something thats not gonna over power the smaller boston cr67s i have as surrounds (dont think it would be too much of a problem but i figure i would just make sure) i can get a good deal on a denon, rotel, krell, or yamaha from the dealer i always go to, krell is problably gonna be out of my price range, and would like to stay away from yamaha, i can get the Rotel RSX-1057 under 1k, Denon AVR-2807 for about $800, Denon AVR-3806 just under 1k, and the Denon AVR-2808CI for about $900, it prolly seems like im going on and on with this but it just seems like soo much to go over and like there isnt really a difference between any of them, gonna get some final prices tomorrow and hopefully get a good deal on something.

 

[Seth=L]

First, the Rotel is not the best bang for buck among the bunch, and not as up to date either.

Don't be concerned about damaging the Bostons being used as surrounds, the surround channels rarely use more than 10 watts per channel at any given moment.

If you need HDMI, the Onkyo TX-SR805 is hands down the most cost effective and also likely the most powerful and well equipped to handle low impedance loads. It is the only one of the HDMI featuring receivers that has THX Ultra cert. which guarantees certain things such as ability to drive 4 ohm loads.

As mentioned before, if you have no need for HDMI (you haven't said as far as I can see) the JVC RX-DP20 is a viable option. It too has THX Ultra II cert. and is a 50 pound receiver. The suggested retail for it in 05' was over $2000. It is certainly the best looking out of the bunch, save maybe the Rotel. If you did get the JVC you would have enough spare money to invest in speakers, perhaps to get a matching center to go with the Logans, or a subwoofer upgrade. Speaker and room acoustic upgrades will get you much further in terms of upgrading SQ vs. amplification and other mid-front end components.