Sub Pre-out = is it that important? (1 Viewer)

[Rich Moorehead]

im looking to get the Denon DRA-685 stereo receiver but it has no sub pre-out and i want to get a sub.what other ways can i hook the sub up? and will it compromise performance of the sub at all? by the way, the sub is a HSU vtf-2. thanks guys.

 

[BobAZ]

I'm not familiar with that sub, does it have IN/OUT terminals to connect speaker wire? If so then run speaker wire from Rcvr L/R Out -> Sub -> L/R main spkrs.

 

[Rich Moorehead]

but does doing that compromise performance?

 

[JamesHl]

I assume since you're getting a sub, the speakers that you have don't have good bass response, so you should probably also consider getting a high pass filter.

I don't think it should affect the sound quality too much, but I don't have a lot of experience in these matters, either.

 

[Bob McElfresh]

Well as long as you are only going for 2-channel music - you can get away with it. You can always run speaker wire to the sub, let the sub strip off the sounds it wants, then more speaker wire to your L/R speakers.


But... good AV receivers with Dolby Digital, 5.1 outputs are available for $300. Why do you want a stereo-only receiver?

 

[Rich Moorehead]

you get the most bang for your buck with a 2 channel. instead of paying to power 5 or 6 speakers, you can get a very powerful receiver to power 2 speakers for cheap. say denon for instance, their dra-685 is 100x2 and i can get it for 300$. if i were to get a denon surround receiver that powers 100 to each channel it would be like 800$ or more.

 

[BrianEK]

as Bob said you can pick up some good surround sound recievers for a similar price and there can be some advantages to them as well. what's nice about 5.1 capable recievers is first of all they have the subwoofer pre-out you were looking for. As well as if you don't mind putting in the extra speakers it makes music much better. You can put many recievers in an "All channel stereo" mode where you will hear stereo sound from all speakers in the setup, and it fills the room with much more sound since it is coming from all directions instead of only 2 l/r speakers. (I found this ideal for myself when listening to music on my 6.1 system.) They also have the appropriate jacks for hooking up high resolution audio players like SACD and DVD-Audio. If you are mainly using the reciever for music this can be nice because this year SACD and DVD-Audio have grown in popularity and i'm sure at some point all recording artists will be recording in a high resolution format. these two formats have twice the resolution of a normal cd and many are in 5.1 surround sound, and it's the most unbelievably clear thing I have ever heard! Also one thing to remember when your shopping for a reciever, don't just look at wattage because it can be misleading. For example some recievers like Harman Kardon or Onkyo are "high current" recievers that list wattage differently. for example the HK AVR525, that retails $999 only has 75watts/channel, but because it is high current, that is a constant wattage you get per channel. whereas non high current recievers list wattage as dynamic, meaning the maximum power the reciever can output at any given point in time. Just so you know. But those are the advantages of a 5.1 capable reciever but you will most likely spend more money on one. It all comes down to what you want to do with the reciever, if all you want to do is 2 speakers and the above advantages don't sound like it's worth the extra cash, go for the 2 channel reciever. hope this helps a little.

 

[Brian Fellmeth]

As well as if you don't mind putting in the extra speakers it makes music much better.

This statement is argueable. A well set up 2 channel system sounds MUCH better than a surround setup with a stereo source. Having sound comming from all over the place completely destroys the 3 dimensional soundstage that exists when stereo is done right.

As to your original question- does performance suffer if the sub is fed by other than a sub out- no simple answer to that. Look at your goal- the sub gets the deepest bass and smoothly transitions to your stereo mains somewhere between 50 and 100 Hz (depending on the bass cababilities of your mains). So 2 things have to happen. The signal to the sub has to have high frequencies stripped off and the signal to you mains needs the deep bass stripped off. There are many ways to do this. The separation can take place at the line level (before amplification) or at the speaker wire level. A HT receiver does it at the line level and in fact does it in the digital domain. So what you are really asking is- can I do as well or better separating my signal than the line level digital crossover in a typical HT receiver.

Using a stereo receiver, you always have the option of sending the full range output to the Hsu, then use the speaker level outs on the Hsu to your mains. When you do this, the Hsu converts the signal back to line level, applies its onboard crossover to strip off the high frequencies, then reamplify the signal and send on to the sub driver. It then applies a very rudimentary high pass crossover to the signal that appears at the speaker out leads for the mains- probably just a cap in series with the signal. This works fine, but getting a smooth transition will invlove some luck.

Probably better is to make the division at the line level. This is only possible if your denon gives you access to the line level signal ("pre outs"). Sometimes these exist as jacks that are jumpered to the amp section with curved bars that can be removed. If you can get your hands on the line level signal, then it can be split without consequence and used to feed the Hsu's RCA in jacks where the signal is filtered (low passed) and amplified. The messy down conversion from speaker level to line level is avoided which is good. But you have no way to strip low frequency from the signal to the mains which is bad (you lose one of the benefits of a sub- unburdoning the mains of even trying to produce deep bass). Some subwoofers have line level high pass filters for this purpose, but the VTF-2 is not among them. As noted above, it does have a speaker level high pass, but this is a rudimentary low slope filter that I would not allow to mangle my main signals. You can kill the low frequencies relatively cheaply with passive line level filters (ACI, audioc.com has them).

The best option is to filter the line level signal properly with an active device that creates both low passed (for the sub) and high passed (for the mains) signals such as the Paradygm X-30 which will set you back about $120 used. Or you can build your own for about $80 in parts.

Bet the HT receiver option is looking better.....