Adding a Sub to complement full range speakers, need advice

[CoolBeans]

Hello everyone. Been lurking around these forums for a while and finally bit the bullet and created and account to ask for help. I will try to explain my situation the best I can, so I'm apologizing in advance if this gets a little long.

I got a vintage set of amp and tower speakers which holds sentimental value. I'm sure it is nowhere near 'high end' in audiophile standards, but I am very pleased with the sound for the most part. The amp in question is the Pioneer SA-610 and the speakers driven by it are a pair of Pioneer CS-656. I use them for both music and movies, basically any kind of multimedia. I also don't really like very loud sound, I never really turn the knob above 1/4th.

My only complaint here being the bass. Anything bellow 100hz starts getting lowered in volume, while at 65hz and bellow the imbalance really gets noticeable. I also ran some tests, and it looks like they can only reproduce sounds as low as 34hz, anything bellow is completely lost. The 'loudness' switch on the amp seems to alleviate the volume differences in the mid-sub range, but sound becomes a little too fake and 'boomy' while the deeper bass is still playing too low (or doesn't exist at all).

So, I decided I need to complement my setup with an independent sub, ideally kicking in at 100hz and bellow. But here is where I'm starting to get a little confused as to how to make this work. I would like to keep my tower speakers at full range, meaning I don't want to introduce any crossover cut-off for them. Is it possible to have a sub with - possibly - its own crossover control (active?) so it will only receive certain frequencies, leaving the other two speakers perform the same as they are now and not introducing more stress to the amp? Also, since this amp only has the good old stereo speaker connections, could I somehow connect the sub on the same outputs, using some sort of a Y-split gimmick, again without affecting the tower speakers? Finally, what sub would you recommend that would play nice paired with this setup? I'm not looking on anything really high end, just something that would fill the gaps of my current system and blend in without overpowering the rest.

Sorry if this is too long to read. I'm not very knowledgeable so I tried to be as specific as I can. Any advice would be really appreciated!

 

[shadyJ]

There are several things you can do here. You can get a subwoofer that accepts speaker level inputs, meaning you can connect the speaker wire to it. Some subs have speaker level inputs and outputs, so you can go from the sub back out to the speakers. Some subs only have a speaker level inputs, so your amp will need another set of outputs. If your pre-amp has an open set of pre-pouts, you can just run those to the sub, or you could use Y-splitters like you describe, and route the signal to the sub that way.

If I were you, I would filter out the bass from the speaker, so I encourage you to use a crossover. If your speakers are starting to lose it below 100 Hz, they probably can't drive bass frequencies that well. That means they are very likely generating a good amount of distortion, and this distorted sound will stretch across a broader spectrum of frequencies than just the bass. Using a crossover with a high pass filter might be able to significantly clean up the sound. You might look into something like this, if not a modern AVR with pre-outs for your amp.

Some good brands: Outlaw Audio, Hsu Research, Rythmik Audio, SVS, Monoprice Monolith.

 

[CoolBeans]

There are several things you can do here<...>

Hello and thank you very much for your advice. You are right, crossover is probably my best bet since there would be no reason to let the speakers overlap with the sub. Passing them through the sub itself and splitting the frequencies sounds like a tidier approach.

I've done some research and I found a sub that might work for this (although I'll have to check again now that you suggested those brands [edit: Ouch, those are too expensive]): "Magnat Supreme Sub 301A". It claims it can go as low as 16hz which should pair nicely with this amp that supposedly can go as low as 15hz. It also has both speaker level ins and outs. Here's a picture I found online:

Do you think this would be a good option? Would passing the speakers through it affect the sound quality in a negative way?

Also, one more question if you're still with me. I'm not quite sure how the independent volume knob on the sub works. Does it work together with the amp? Meaning, if I set it to a certain level, would it still scale when I raise the volume on the amp itself, or would I have to constantly tweak it to match the rest of the sounds? (Sorry, I'm a newbie)

 

[shadyJ]

You are in the UK or Europe I take it?

Passing the speaker wire through the speaker level inputs and outputs will not do anything significant to the signal. Don't worry about that. The only problem with that is it creates a lot of wiring, so potential for a spaghetti mess.

The volume knob on the sub will boost the signal that the sub receives. The volume knob on the amp will boost the signal that is sent to the sub, so you can increase it wither way.

By the way, no way that sub is seriously digging down to 16 Hz. That is a clearly exaggerated spec. It should still get plenty deep for music though. I wouldn't be surprised if that 16 Hz spec was at -10 dB or something like that.

 

[lovinthehd]

Ideally you set the gain (volume) on the sub's amp initially to match up to the level of your speakers (assuming you're using the speaker level inputs/outputs), then leave it alone and use the volume on your receiver so sub/speakers are controlled with the single volume knob. I'd agree 16hz is a bit of a fantastic claim for that sub....

 

[CoolBeans]

Yes, I live in Europe. That 16hz is probably there for marketing purposes, I agree, since I have now looked up much more expensive and higher end subs that don't claim to go as low.

The wiring is not an issue, I work in IT and I'm very skilled when it comes to cable management In the end it will all look nice and tidy. I only hope there is no interference.

I'm a bit confused about the gain/volume knob. I thought it is supposed to only tweak the volume of the sub itself, not the whole signal. But since speakers will be passing through it, the latter does make sense.

Edit: I'm trying to figure if this sub actually cuts off the lows from the speakers with its crossover setting or if it's there just to configure when the sub kicks in...

 

[lovinthehd]

When using the speaker level inputs the sub's amp only takes a signal, really doesn't have a lot to do with the normal amp/speaker relationship. The gain adjustment on a sub is to adjust the sensitivity of the sub amp, so as to match it to the input level (whether a line level input, as pre-out voltage varies with pre-amp), or the speaker-level input it's taking signal from.

The sub you mention seems only to have a low pass filter, your speakers will still get a full signal, you'll be limited to trying to blend the speaker's native roll off to the sub's. There are some subs that offer in their circuitry a high pass filter for the speakers, sometimes only line level, sometimes speaker level, but generally a feature that's not found on the majority of subs it seems to me....

 

[CoolBeans]

Alright, I think now I understand everything. If needed, I can always add a separate filter between the sub and the speakers I guess.

Thank you both for taking the time to help me with this, much appreciated!

 

[lovinthehd]

Well a modern avr would be easier in a few ways if you need any other reason to change up....you could read something on why sub Schroeder frequencies and room interaction are important, that's always fun Maybe this one https://www.soundandvision.com/content/schroeder-frequency-show-and-tell-part-1

 

[CoolBeans]

Well a modern avr would be easier in a few ways if you need any other reason to change up....you could read something on why sub Schroeder frequencies and room interaction are important, that's always fun Maybe this one https://www.soundandvision.com/content/schroeder-frequency-show-and-tell-part-1

Hehe I realize that, but I would very much like to keep this one as it once belonged to a family member that passed away, and frankly apart from these limitations I quite like the sound Plus I use Plex to locally stream from a computer so there is no need to connect any other video related devices to the amp other than the TV itself (which is also set to PCM so it doesn't compress the sound). Trying to marry old school with modern hehe.

Edit: Very interesting read nonetheless

 

[lovinthehd]

Just what works for ya, sentimentally or technically or both