2 channel amplifier, ohms, and bi-wiring question

sponger

I'm considering ditching the sub and putting the monitor 70s on full-range duty with an external amp. The amp I'm looking at has speaker-level inputs, so my receiver lacking pre-outs is not a problem. Here's the amp:

http://www.russound.com/product_detail.php?i=3248

1.) It says it does 225W/ chann at 4 ohms and 150 / chann at 8 ohms. Each channel has A/B terminals to make for a bi-wiring configuration, and I initially thought that a standard bi-wiring arrangement (i.e., A to A and B to B for each channel) with the 8 ohm monitor 70s would result in a total of 150 watts going to each tower, with half of the 150 going to the mids and the other half going to the tweeter.

But I read on some forum or another that a standard bi-wiring arrangement will half the ohm load for the amp, meaning that each channel would be producing its 4 ohm rating when connected to 8 ohm towers. I'm not able to find that link again, but is that true?

2.) If not, would it be possible to bridge the A and B terminals of each channel of the amp to make that 4 ohms per channel happen? The manual illustrates only a mono bridging configuration.

Drenis

That is full of wrong.

You need a pre-amp or AVR with pre-outs. I would flip both for a better pre/AVR pending your needs.

sponger

The amp has speaker-level inputs. The manual clearly states "A speaker-level input can be connected and assigned as either the primary or secondary source." These are the same type of speaker-level inputs found on, say, the average subwoofer amp. I understand that the vast, overwhelming majority of stereo amps or any full range amps for that matter do not have speaker-level inputs, but this amp is an exception to that rule.

Drenis

Then have at 'er.

I'm out on this one.

sponger

You don't want to answer my question and take advantage of the opportunity to school a newb on basic HT principles? My naivety is waiting.

chumlie

I would suggest you contact their support center and repeat your question to them.

sponger

chumlie wrote: »

I would suggest you contact their support center and repeat your question to them.

This question would apply to all 2 channel amplifiers with A B channels for bi-wiring, which is a feature that most 2 channel home audio amps have. The only thing that makes this amp and thus this question unique is the speaker-level inputs, which isn't relevant anyway.

ravaneli

you have only two channels, dude. There is nothing to bridge. A and B are alternatives, they cannot be used simultaneously.

Biwiring uses a single channel going to both pairs of posts on the speaker. It does NOT change the impedance.

Also you may want to know that biwiring is totally worthless anyway. Just wire them the normal way and they should sound great with that amp. There are no gimmicks to be done with your setup.

sponger

ravaneli wrote: »

you have only two channels, dude. There is nothing to bridge. A and B are alternatives, they cannot be used simultaneously.

Biwiring uses a single channel going to both pairs of posts on the speaker. It does NOT change the impedance.

Also you may want to know that biwiring is totally worthless anyway. Just wire them the normal way and they should sound great with that amp. There are no gimmicks to be done with your setup.

The manual states the following:

"Speaker selector - select speaker pair A (main) or speaker pair B (auxiliary) for
audio output. You can use speakers A and B together, as long as the speakers
are at a minimum 8-ohm impedance."

But I'm beginning to get the notion that what that paragraph is saying and what I'm interpreting from it are two completely different things. I had high hopes that there would be a way to extract the 4 ohm output with these 8 ohm speakers, but reality is finally starting to set in. I guess the loss in damping factor from the ohm reduction would not be worth the extra power output anyway?

Thanks for the reply. It is much appreciated.

tonyb

Sponger,

Lets review your gear first. You have M70's up front, these are some of the easiest speakers to drive and do not require tons of power to sound good. Your receiver is on the entry level side as with the sub. Nothing wrong with all that, but adding an amp should not be the first thing on your list of gear to look for.

My suggestion is to first think about what you don't like about your system, a budget you have to work with, and we can go from there. You can get a better bang for your buck by going used from Audiogon, Craigslist, or our own FM.

sponger

tonyb wrote: »

Sponger,

Lets review your gear first. You have M70's up front, these are some of the easiest speakers to drive and do not require tons of power to sound good. Your receiver is on the entry level side as with the sub. Nothing wrong with all that, but adding an amp should not be the first thing on your list of gear to look for.

My suggestion is to first think about what you don't like about your system, a budget you have to work with, and we can go from there. You can get a better bang for your buck by going used from Audiogon, Craigslist, or our own FM.

I'm actually very satisfied with this set-up. But, two things. 1.) Rarely use the sub. Full range, the 70s make all the bass I really need. 2.) As great as they already sound, there's a consensus that they could sound even better with more power.

So, with those two things in mind, I've narrowed it down to simply needing more power for the 70s so they can run at full range to their fullest potential. With speaker-level inputs, this amp seems to be the end-all solution for my humble needs.

tonyb

Then get a receiver with pre-outs, add an amp if you want, but personally I would get a beefier receiver with preouts and upgrade the speakers to the RTIA series before adding an amp.

I say this, because that upgrade bug always is nipping at your heels. Preouts give you more flexability in the amps you use which is key. It won't be long before you want those big 4 ohm towers that you came across at a good price. Happens to all of us. Thing is, you need gear that offers you flexability to the upside. Good luck to you on your journey.

nguyendot

1) Not having preouts IS a problem if you plan on using an external amplifier. If you want good sound, then speaker-level inputs should never enter your train of thought. It's going to sound like crap, look like crap, and you'll be the laughing stock of the forums. But hey, if you like it...I suppose whatever. Speaker level inputs never, ever sound as good as line level because the signal is not nearly as clean.

2) All the A/B switch on that amp does is gives you a hardware splitter/switch inside the amp. Nothing more, nothing less.

sponger

Well then I guess there's no other option besides feeding the upgrade monster. The thing is that I want to stick with Denon because of the Audyssey calibration. Yammies seems to be more versatile in a lower price bracket, but pretty much all the forum mining I've done turns up opinions that rank the YPAO calibration beneath all others.

It's $1,200 right now for a Denon receiver with component audio outputs. $649 is the entry fee for a receiver with "multi-zone" pre-outs, which I guess would work for the front L/R channels?

ravaneli

in reality you only need FL and FR preouts.

go to accessories4less

Great deals, you can get a great quality refurb for 300-400

tonyb

Go used, your money will buy more quality per buck. You can get a nice receiver from Denon or Pioneer a couple years old in the sub 600 buck area.

sponger

Thanks for the suggestions. Didn't even know about accessories4less. I had been looking at dakmart only for refurbished HT gear.

Not sure if it really matters, but hdmi 1.4a and 3d pass thru seem to be missing from receivers that are more than a year old with a few exceptions here and there. Crutchfield has the Marantz SR6006 for $799, which is $200 cheaper than the "clearance" price at the local audiophile store. With that receiver producing a rated 110W/chann, and with Marantz tending to be underrated from what I've read, I'm hoping it will circumvent the need for external amplification. 75W/chann with these towers doesn't sound bad at all, so I figure 30W more could only sound better. Plus it's a Marantz.

ravaneli

I have the SR5006 which has the same amplifier inside and it's a great unit. Even marantz overstates their watts though. How can a 650 W power consumption feed 7 x 110W ? The unit would create energy out of thin air : )
However that unit allows you to use the power from the rear two channels towards the front - biamping. Lot's of opinions about this. In 2.0 biamping definitely outputs more power than the front two channels alone. However 100 W to woofers + 100W to mids and tweeters (even if it is 100W) is not the same like a single channel feeding 200W. I would still biamp them because it certainly doesn't hurt.
I bought my 5006 for accessories4less. The unit was packed and looked and still works like brand new. I would not hesitate to buy from them again.
At the end of the day no conventional receiver will power to full potential these towers. Too bad a4l doesn't sell nice amps. I would get a cheap receiver with preouts from them and get some amp later..

Drenis

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