Combining two channel and surround (1 Viewer)

[macfan]

Greetings all, I'm an audiophile about to upgrade to surround. I currently have some vintage McIntosh stereo equipment (a 35 yr old classic 200 watt per channel MC2205 power amp, with a 1 year old MC220 tube preamp, etc.) driving two JM Lab Cobalt 826 tower speakers and a matching Cobalt SW800 sub. Maintaining my ability to use the Mac equipment for two channel music is very important to me.

I'm currently awaiting delivery of an Onkyo TXSR875 and JM Lab Cobalt center channel speaker. I have already have the Cobalt 806 bookshelf speakers sitting in my closet, which will be ideal rear speakers for the surround system. The five Cobalt speakers with the matching sub is actually ideal for surround. What I'm being told is, while using surround, I can have the Onkyo drive the center and the rears, while letting the Mac drive the front towers and the sub. So in essence I'll be maximizing the system's potential by incorporating both amps, and still be able to listen to two channel when I choose.

Does this sound right? Thanks in advance for your input.

Ed

 

[Selden Ball]

It not only sounds right, but it should sound great!

The actual connections might be a little tricky. It looks like hat model of Onkyo has preamp inputs and outputs, so that part's OK.

Some stereo preamps have a unity-gain HT bypass to make them easy to use as part of a multichannel audio system. I dunno if yours does.

 

[macfan]

Well, the equipment is in, but I can't get it to work yet. From the Onkyo, I'm connecting from preamp out to two inputs (Tape) on the McIntosh C220 preamp, which is connected to the Mac power amp, which is sending signals to the two front speakers. The Mac preamp is connected to the (self-powered) sub. Two channel music is of course working great, but when I turn on the Onkyo and listen to the TV, right now I get no sound of the fronts and the sub. My sense is the Mac pre is not receiving a signal from the Onkyo TXSR875.

If I must surrender, I can always just devote all 5 JM Labs speakers to the Onkyo, but then I'd have to use different speakers for two channel, which I'm trying to avoid.

Anyone have any experience with such a setup? I'll confess I ran out of gas last night and didn't spend much time with the Onkyo setup. The manual kind of sucks, and it devotes one third of a page to "connecting to another amp."

 

[Selden Ball]

How is your TV's audio connected to the Onkyo?

I would expect that connection to be either red/white analog cables or digital audio (usually optical).
If you're using a digital connection, you may need to associate that digital input with the TV section of the receiver.

(An HDMI cable between the receiver and the TV only carries audio and video signals from the receiver to the TV. Only control signals go from the TV to the receiver over HDMI.)

Some tests I'd do:

Connect the CD player to the tape inputs on the McIntosh preamp to make sure that input doesn't have a problem.

Connect the CD player to the CD input on the receiver, and connect the receiver's "monitor" or "tape" outputs to the CD input of your McIntosh preamp. That would test the cables and verify that at least some of the electronics in the receiver is working as it should. (And you could hear just how much distortion is introduced by the Onkyo.)

Connect the other Onkyo preamp outputs to the CD input on the preamp, just to hear if any audio at all is getting through the receiver to the McIntosh preamp.

 

[macfan]

Thanks Selden, from the Onkyo, I only have HDMI out from the Onkyo to one of the HDMI inputs on the Sony XBR. My impression is, while using surround, the TV is really only a monitor, and the Onkyo is passing, or processing video to the tv, while sending audio to the various speakers. All inputs on the McIntosh preamp are sound, and interconnects are extensively upgraded. I'm hoping it's merely an initial setup issue with the processor. The guys that sold me the Onkyo and the center channel will be on the phone with me this evening to guide me through the setup process.

Wish me luck.

 

[Selden Ball]

Ed,

If you're using an external cable or satellite box to get your TV stations, then it needs to have its own audio and video connection (HDMI or otherwise) to the receiver, and that's where the sound will be coming from. However, if you're using the TV's internal tuner to get over-the-air or cable stations, then you need a separate audio connection from the TV back to the receiver.

Have fun!

 

[macfan]

Yes, I have HDMI coming in to the receiver from DirecTV High Def DVR.

For the last couple of years I've had "surround" through a Yamaha YSP-4100(?) sound bar, so conceptually, as far as inputs and such, I've got a handle on it. What's got me whacked is the communication between the Onkyo and the McIntosh beast. I'm just wondering if it's do-able.

I'm getting sound to the center channel, and I've yet to hook up the rears. I'll do that tonight.

Maybe if I have a couple of beers it'll make more sense.

 

[Selden Ball]

ed,

Best of luck!

I have no personal experience with Onkyo receivers, so I can only help in a generic sense. (I use a Marantz AV8003 pre/pro.) The Onkyo manual just says you can connect its preamp outputs to any external amp.

Certainly if you get sound from the center speaker, audio is getting to the receiver. I guess the next question is why nothing is getting from the receiver's preamp outputs to the McIntosh.

It certainly should be do-able: line level outputs are line level outputs, no matter if they're coming directly from a player or a preamp output of a receiver.

 

[macfan]

Thanks Selden, I got it up and running. My problem was I wasn't giving the Mac preamp enough volume. When I listen to two channel, it's REALLY loud at around 35 on the digital volume readout, so I was afraid to turn it up beyond that. It works fine when I turn it up to around 55 or 60 (it will go up to 100). I notice a very slight hum through the two front speakers when the audio through the Onkyo goes silent, so I think some balancing will be required.

Now I'm confused about the sub. They told me to connect from preamp out labeled "sub" to the LFE input on the sub, but it's making a humming sound instead of producing bass. That's odd...it works fine when playing two channel (it's also connected to the Mac preamp outputs). More communication with the vendor tomorrow.

Is it all gonna be worth it?

Thanks for listening.

 

[Selden Ball]

ed,

It's good to know you've got it almost working!

The most common cause of hum is using different phases of incoming power.
Are you using different wall outlets for the receiver and for your McIntosh and amps?
It's easiest if you can use a single wall outlet with a multi-outlet power strip so all of the incoming power connections are at the same potential at the equipment (cable box, receiver, players, TV, preamp and amps).

However, grounding of the incoming TV cable is especially problematic and is a common cause of low level hum. You might want to try to get the cable company to do a better job of that where the cable enters the house. If necessary, isolation transformers are available which go inline between the cable and its decoder box.

You don't need to connect the sub to the receiver. Leave it connected to your fronts as you always have. You don't need to compromise your existing 2.1 speaker configuration.

Instead, configure the receiver for no subwoofer but with full range fronts. The receiver will properly fold movie LFE audio into the two front channels. The other channels' low frequencies (below whatever crossover frequency is set in the receiver} will also be sent to the front channels. As a result, all of the lowest frequencies will be sent to the front channels and will wind up coming from the sub. Low frequencies that are above whatever crossover you're currently using between the sub and your fronts will come from your front speakers. LFE audio extends up to about 120Hz, so your fronts' woofers will be getting somewhat more of a workout than in the past, especially if you watch many action movies.

 

[Selden Ball]

duplicate post deleted.

 

[macfan]

Hey Selden, thanks so much, you're absolutely right. With this setup, the key is to tell the Onkyo there is no sub, not connect from pre-out and let the McIntosh do it's thing. They had told me to hook up from Onkyo to LFE, I guess out of habit. Big sigh of relief here. I have a pretty pricey sub, and really wanted it to work with surround.

As for the slight hum, I'm going to experiment with outlets. I can't plug the Mac and the Onkyo into the same outlet, but possibly if I get them all into similar purge protectors (at this early stage they're kind of scattered around haphazardly) it'll make a difference.

I suspect that I need to get a better balance for the fronts between the Onkyo and the Mac. Possibly if I adjust the volume setting for the fronts in the setup menu, I won't have to Mac pre set to such a high level for balance. Does that make sense?

Thanks again for your help.

Ed

 

[Selden Ball]

Ed,

Your plan for the power sounds (reads?) fine to me.

Since your McIntosh doesn't have a unity-gain pass-through, I'd suggest deciding on a specific volume level setting to be used whenever you use it with the Onkyo. Then run the Audyssey equalization setup in the Onkyo. It'll optimize the relative volume levels that the Onkyo will use for all of your speakers. You can adjust them afterward if necessary.

The Audyssey instructions in the manuals provided with most receivers are sketchy at best. Detailed instructions with explanations are available on the AVS forum site in the Audyssey thread at
http://www.avsforum.com/avs-vb/showthread.php?t=795421

Along with lots of other advice, it includes these links:

The Audyssey homepage: http://www.audyssey.com/

The types of Audyssey in different receivers:
http://www.audyssey.com/technology/multEQ_products.html

The Audyssey FAQ: http://www.audyssey.com/faq/index.html

The Audyssey setup guide:
http://www.avsforum.com/avs-vb/showthread.php?p=14456895#post14456895

 

[macfan]

Selden, I did adjust volume settings for the fronts on the Onkyo UP while turning the Mac DOWN, and that did the trick. No more hum.

I haven't run the Audyssey setup yet. I've been so busy grinding on this other stuff i forgot about it. Thanks for the links.

As for now, I'm thrilled. I have surround, with the amps working in combo, and can effortlessly switch to two channel for music. Maybe now my family can start to enjoy this fine new toy.

Thanks again for your help, and have a great weekend.

Ed

 

[Selden Ball]

Ed,

You're very welcome.

Keep warm!

 

[macfan]

Hey Selden, I've listened to the system with movies, music and tv and it sounds outstanding. The sub sounds very active as well.

I've also done some reading up on the LFE input, which I am not using. The Onkyo is set to full range on the fronts, so the sub is working actively with the Mac, and it's very involved with the movie action and effects, or so it seems. As I understand it, the LFE is simply meant to feed all low frequency signal to the sub, and nothing else. So in theory the sub will pick up the low frequency effects not being sent to the fronts, center and rears according to the crossover set in the receiver's speaker setup menu. Since I have the fronts set to full range, the sub is picking up the low frequencies from that channel. But it is not picking up the lows sent to the center and the back speakers.

So, do you think I'm missing some bass effects in Dolby Digital by not utilizing LFE? For what it's worth, we watched Transformers 2 (crappy movie, but great effects) and it's hard to imagine the system much better. But you know how we roll with this kind of thing....I want all I can get.

Ed

 

[Selden Ball]

Ed,

Did you verify
a. that the receiver's subwoofer output is disabled
b. that the crossover frequency is set to a reasonably high frequency in the receiver and
c. that the center and surround speakers are set to "small" in the receiver?

In principle, those three settings in combination should cause all of the low frequencies from the center and surrounds to be redirected to the fronts.

If you've run Audyssey, it often leaves all speakers set to "full range", so that the receiver's bass management crossover frequency is ignored. Changing the speaker settings to small and (if you need to) raising the crossover frequency won't affect the room/speaker equalization response curves that Audyssey has generated. (Lowering the crossover frequency does cause problems, though, and usually will cause Audyssey to be disabled.)

Some receivers implement separate crossover frequency settings for the different speakers, while some have only a single common setting. Without reading the manual, I'm not sure which your receiver implements.

 

[macfan]

You can set separate equalizer settings for each channel. Is that the same as crossover settings?

 

[Selden Ball]

They're not the same, although they do interact with one another.

Equalization is the process of matching of a speaker's frequency response to the room's acoustics so that you hear a more accurate sound at all frequencies.

Frequencies below a channel's crossover frequency get redirected from the original channel to the subwoofer channel (if enabled) or to a full-range front channel.

I'm in the process of trying to download a manual for your receiver, although it's going really, really slowly.

 

[Selden Ball]

The speaker settings I've been trying to describe are documented on page 86 of the manual. They're in menu #1 "speaker settings" of the "speaker setup" menu.

Set subwoofer to "No." Fronts automatically get set to Full Range.

Apparently you can set either "full range" or the value of the "crossover frequency" for the other speakers. (Other models of receivers don't always handle it that way.) The example of 100Hz is a reasonable place to start. You may need to use higher or lower values depending on the frequency ranges of the center and surround speakers you have.

The LFE low pass filter should be set to its maximum (i.e. effectively disabled).
Note that LFE is not synonymous with subwoofer. The LFE channel is a special sound effects channel included with most movies. It contains low frequency sound effects which can go as high as 120 Hz. Properly mixed multichannel music discs don't include an LFE.

The "equalizer settings" menu provides access to a 7 band equalizer. You can use these manual settings as an alternative to automated Audyssey equalization. However, Audyssey makes adjustments to the audio in many more frequency bands than the manual equalizer provides access to and optimizes the sound quality over a broad area.

I hope this helps a little.