Rotel RX 602

[pull225]

Hi all,

I'm looking at a 1976 wooden 602 that is in mint condition. I don't know anything about this unit and hope someone can shed some light on the power rating please. I have some old Magneplanars but i don't think this unit would have enough power to run them with a turntable? I could set it up as a separate system to run a CD player in my garage. It is selling for $125 and I love the look of it.

Thanks!

[srb]

Whether the RX-602 might have enough power to drive the Mangeplanars has less to do with whether a turntable or a CD is your source (other than a turntable needs phono preamplification and equalization, either provided by the amplifier or receiver having phono inputs, or if not, with an external phono preamp) and more to do with the power output and power supply of the amplifier.

The RX-602 does have phono inputs, so you would not need an external phono preamp.

Magneplanars are generally 4 ohm nominal impedance and relatively low sensitivity in the 86dB range, and benefit from powerful amplifiers with good current capability. The RX-602 is rated at 35W/ch @ 8 ohms. It is able to drive 4 ohm loads, and although the power at 4 ohms is not specified, a reasonable guess might be in the 50W to 55W/ch range.

It would depend on the volume level of listening, your distance from the speakers and the size of the room. For moderate levels in a small room it may work fine, but I have no doubt the Magneplanars would also benefit from additional power.

Steve

[wkhanna]

Terrific advice.

Thank you, Steve

[pull225]

Steve,

Thanks for the great input and you got me thinking about what is the correct power to run the Magneplanars? My current set up is an HK receiver AVR 3600 7.1- Channel A/V Receiver with 80 watts times two at 8 ohms. I thought that the Rotel may have had more but you help clarified.

Can you provide some basic guidance on what to look for in an amp for my speakers? My room is 16’ x 16’ with 9’ ceilings. I prefer a moderate level of volume and am looking to add a subwoofer to help the Magneplanars with some bass.

Thank you.

[srb]

What model of Magneplanars do you have? What is your listening distance from the speakers?

When you mention "what to look for in an amp for my speakers", are you talking about an additional 2 channel power amp connected to the preamp outputs of the HK versus a more powerful receiver?

Steve

[pull225]

My speakers are old - late 80s - MG-Ics. I could dig out the manual and provide specs. My listening distance is 10' - 12'. My thought was an additional amp hookup to the preamp outputs.

[srb]

I don't think I was too far off, from what I could find the MG-Ic appears to be 5 Ohms with 85dB sensitivity, if the specs in this chart are accurate. http://www.integracoustics.com/MUG/M.../speakers.html

Using a handy SPL Calculator for ballpark calculations (http://myhometheater.homestead.com/splcalculator.html), it would indicate that with an 80 watt amplifier driving 85dB speakers you could expect peak output of ~ 96dB at a distance of 11 feet. I don't know how much more power the HK AVR 3600 might output at 5 Ohms, but it would be a bit more.

If you add a subwoofer and high pass the Magneplanars at ~ 80Hz, you would be able to get a little more volume and/or dynamic range from them and not tax the receiver amplifier as much.

What is your budget for a subwoofer? Perhaps the best plan of attack would be to first add a subwoofer and see how the existing receiver + sub works for you in your room. You might be satisified with the sound. If you decide you want to add an amplifier for even better control and dynamics, there are a number of ~ 125W @ 8 Ohm / 200W @ 4 Ohm power amplifiers that you can find used in the $350 - $400 range, such as a Rotel RB-1070, Parasound 2125, ATI 1202, Audio Refinement Multi-2, etc. and you can find older models for even less.

Steve

[pull225]

I checked the manual and you are correct. Purely resistive, 5 ohms at any frequency. I think a good next step would be to buy a sub and see how everything sounds. I was looking at SVS PB1000 10-inch 300 Watt Powered Subwoofer at $499. I didn't want to spend that much but am fine if it gets the job done. My head was spinning just to get to a point where I could pick a sub. Way too many choices...

[srb]

I was looking at SVS PB1000 10-inch 300 Watt Powered Subwoofer at $499. I didn't want to spend that much but am fine if it gets the job done. My head was spinning just to get to a point where I could pick a sub. Way too many choices...

For the same $499 you may also want to consider the SVS SB-1000, a 12" sealed version. While the ported PB-1000 may have a little more output and reach a bit lower for home theater use (the sealed SB-1000 goes down to 24Hz vs 19Hz for the ported PB-1000), I prefer sealed subwoofers for music, and feel they offer a tighter, more accurate bass.

Steve

[wkhanna]

SVS & HSU have both earned respect as being V good values.

[pull225]

I just order the SB-1000. I will report back once I have it hooked up.

Thanks!!!

[srb]

Congratulations!

Some people use two, three or four subwoofers to equalize and smooth out bass peaks and nulls in the room. Not that I'm recommending that for you, but a single subwoofer might even take a little more experimentation to find the best location in the room.

Then you will need to dial it in, experimenting a bit with sub crossover frequency on the AVR (60Hz or 80Hz - doesn't appear the AVR 3600 has crossover frequencies in between), the relative volume level of the sub and maybe even the phase adjustment on the sub itself.

So I would be interested in your initial assessment when you first get it setup, and then it's likely you can further improve upon it with a little tweaking until you find the best settings and sub location (within your physical sub placement limitations) for your setup.

Enjoy!

Steve

[pull225]

Hello, I'm back with an update. I have the SVS SB-1000 12" sealed version installed and the system definitely benefits with the added bass. But, I am still not getting the output to my Magneplanars. I have to stand 2 feet from them to hear any output above what the center channel puts out.

I have the front Magneplanars crossover set to Large, center set to 60 Hz, and Sub at 80 Hz. I have the levels on the MPs at 10 db and the center and SW are at 0 db.

Any suggestions on next steps? I’m not sure what changes I can make to the crossovers that would help with the output to the MPs.

Thanks.

[srb]

HK only specifies power ratings at 8Ω and the back panel of the receiver says "Speakers 8Ω". Perhaps it is having trouble driving multiple speakers with the fronts being 5Ω.

To start with, I would try setting the Magneplanar fronts to "Small" with a crossover of 60Hz to reduce the power requirements.

According to HK, the speaker level numerical settings are in dB and you have the fronts set to +10dB and the center to 0dB. You don't mention what your center speaker is, but I'm guessing its sensitivity is not greater than 95dB and likely even less (the Magneplanars are ~ 85dB). But for some reason they're obviously still not level matched, so I would try to further reduce the level of the center speaker, as I am assuming it is possible to reduce the level downward from zero to a maximum setting of -10dB as well.

Although an SPL meter is preferable, you should be able to get the levels close enough by ear with the built in test tones.

Steve

[pull225]

Ok, I set the MPs to 60Hz and I turned down the center channel to -10dB. This is better!

The center is a Klipsch, but I don't know anything else about it because I can't find a model number.

I picked up a meter at radio shack and need to figure out how to use it...