Subwoofer Options - SX-838

[Smack2k]

I have ok bookshelf speakers with my SX-838 (due to available space). They are JBL 2500's. I wanted to know if there were any options to add a subwoofer, powered or non-powered, to the system? I'm not sure where one would be connected in the back.

Your advice and assistance is greatly appreciated.

 

[OCNJsquatch]

I have a similar question. My amp is a sansui au717 and I'm looking ta add a McIntosh subwoofer I scored cheap. I have seen diagrams using B speaker wiring to the high level input on the sub. Also heard it's possible to use RCA cables from Play out on the amp to the RCA in on the sub. I'm wondering if there's a Best way? I also have a sansui 7001 which can drive 8 speakers and could use that also. The space is a finished two car garage. And I want to make it my blasting space.

 

[QSilver]

My chose would be to use a high level low impedance input on subwoofer amp. and connect it in with the speakers. In this configuration, the sub follows the amp output. It also means once you've set it up, it'll follow your volume control on the receiver. The sub essentially becomes set and forget. Hopefully the sub amp has such an input on it. Sometimes its marked as "Low Z". This means low imedance.

 

[Bill S]

Connect your L and R speaker outputs from the receiver to the L and R input on the sub. Then connect the L and R speaker outputs from the sub to your L and R speakers. This assumes your sub has high level, speaker outputs (some dont).

 

[Bill S]

Forgive my ignorance, but you are referring to subs with 4 total speaker connections correct? Also, would it be a powered or non-powered sub?

Again, thanks for the information.

I was referring to a powered sub. There are left and right speaker level inputs from receiver to sub and L&R speaker outputs from sub to your main speakers.

 

[peterp1]

You would definitely want an active sub rather than passive (only exception would be if there is a passive sub meant to be paired with your JBL model, which there likely isn’t).

Like many of the better vintage receivers, the SX-838 actually has a preamp output that is hard-jumped to the amp input. You can remove the jumpers and replace it with a Y RCA cable, with one side of the Y feeding back to the amp and the other side feeding the active sub’s low-level left and right inputs

Alternatively, you could also feed the sub using the SX-838’s speaker outputs if the sub has high-level speaker connections. Some subs have 4 speaker connections (in and out) and some have 2 (in only) - either will work. For 2-channel music, I prefer speaker level, most people prefer line level, either will work fine.

Sub selection: Chose a sub that has separate left and right inputs, not one that has only a mono LFE input (there is no easy way to drive it with both channels with the SX-838). In most cases, a sealed sub generally has tighter response for “music only” applications. If you play really loud or want theater effects or play industrial music with deep bass content, a ported will give you a lot more output for the $ invested, but usually that isn’t needed for typical music scenarios

 

[whoaru99]

Some of your question was answered at the end of the previous post.

If the sub has only a single input (sounds like, but not fully clear), then you would need a mono summing adapter to connect the pre outs of Pioneer receiver to the single input of the sub.

Far as connecting both, it's generally never recommended to have two outputs connecting to the same input. A switch would be preferred.

 

[peterp1]

Another "I just dont know" question. Please feel free to poke fun where applicable!!

I have a Powered Sub that is hooked up to my "newer" 2001-ish 5.1 system. The sub only has a line input on it and connects to the pre-amp out on my receiver.

Can this sub be used in anyway on my Pioneer SX-838 and is it possible to split the connection going into the sub to have to connect to both receivers? Only one would be powered on at a time.

Probably a dumb question, but figured I'd ask as both receivers are in the same room (my work from home / hobby room). The Pioneer was my dads that I restored and use to play vinyl and listen to the radio.. The Kenwood 5.1 system is used for my PC's output as well as CD playing. Its been in the room for years with the Pioneer just joining in within the last year.

You could use 1 sub for both by using an inexpensive RCA switch (https://www.amazon.com/gp/product/B075XKZ1Q4/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1) that allows you to select which receiver is driving the sub at any given. You can "split" outputs with Y cable, but you can’t use a Y to "combine" two different outputs (eg the Pioneer and Kenwood receiver), which is why the RCA switch is needed.

There are still some issues. Assuming your sub has only a mono LFE input, you will only be able to drive it with either the left or right channel from the Pioneer. That sounds like a hack, and it kind of is, but it’s really a “95 percent solution” since most deep bass is centered (not panned left or right).

The bigger issue is that the sub’s crossover and level settings will need to be set differently to blend correctly with the JBLs. If your sub has external level/crossover controls, then you’d have to mark the settings with tape and manually set them when you switch. If, instead, all of the sub controls are built into the Kenwood receiver (as sometimes is the case with HTIB “all in one systems”), then you might be out of luck because the Pioneer will send it a full-range signal so that the sub will put out too much upper bass to blend with the JBLs. The sub level will also likely be off (either too high or low). You might "luck out" that a sub setting works good enough for both, but it's typically not that likely./

Depending on which sub you have, and how often you switch back and forth, it might be better to get a separate sub for the Pioneer even though it’s technically possible to share the sub between the Pioneer and the Kenwood.

 

[whoaru99]

Since sounds like you are using just a single connection to the sub, all you need is a single cable from each receiver to the switch and a single cable from the switch to the sub.

Yellow "out" to the sub.
Yellow #1 from one receiver.
Yellow #2 from the other receiver.

(Yes, I know, the yellow says video but it matters not in this case and slightly easier than keeping track of left or right on the switch connections.)

From your HT receiver it's a single sub out anyway, no worries. Plug that to Yellow #1.

From the Pioneer I, personally, would not use just one channel but it certainly won't hurt anything to try it that way from the right pre out to Yellow #2.

If the right speaker no longer works when the cable is plugged into the right pre out, you will need to add a Y splitter to bridge the pre out/main in, and provide a connection to the switch. It would be a Y cable like this style.


The male connections would go to right pre out and right main in. The female end would connect to the switch Yellow #2.

 

[peterp1]

The sub level will also likely be off (either too high or low). You might "luck out" that a sub setting works good enough for both, but it's typically not that likely.

My sub does have the controls on it, so I can look into marking them for each setup.

Now that I think about it more, it might be possible to avoid needing to change the level and crossover controls on the sub whenever you switch receivers. What you would do is start by setting the level and crossover controls on the sub based solely upon what's needed to get a perfect sub blend with the Pioneer driving the JBLs.

Once you have the sub level and crossover set for the Pioneer/JBL combo, go into the Kenwood on-screen menu and adjust the LFE level to compensate for whatever gain change you made on the physical sub. Then use the Kenwood's on-screen LFE frequency to get the correct crossover for blending with your 5.1 system. You should be able to get the level exactly correct. You could also get crossover exactly correct if the Pioneer/JBL crossover is the same frequency, or a higher frequency, than what is needed for the 5.1 system (you'd use the Kenwood on-screen LFE crossover to move the actual crossover lower).

If, on the other hand, the Pioneer/JBL crossover point is a lower frequency than what's needed for the 5.1 speakers (say 60hz Pioneer vs 80hz Kenwood), then you'd have slightly reduced bass output in that narrow 60hz to 80hz window, but it might not be very noticeable.

I suspect that if you start with tuning the sub for the Pioneer/JBL, and then compensate with the Kenwood on-screen menus as described above, you could switch receivers back and forth without ever needing to touch the sub controls.

 

[whoaru99]

You mentioned not using 1 channel on the Pioneer, but would I have any other options if the sub only has the one input?

A mono summing adapter had been mentioned earlier in the thread.

If you search the Internet for Rane's "Why not Wye?"paper, there are diagrams in it to make one using a few resistors. Else Monoprice has a mono summing adaper/converter for $30 (or something like that, anyway).

 

[whoaru99]

I tried this option and if I have only the one cable in the Pre-Amp or if I have a Y-Cable going to Pre-Amp and Main In, I'm getting no sound out of the right speaker. Once I removed the cables and put the jumper back in, the right speaker was working again.

The Y Cable was connected to the switch as well.

Post a picture of how you had it. Can't think of any reason it shouldn't work, except a connection error (or a rare occurrence of a defective Y).

 

[whoaru99]

I can get a photo but Ive checked the connections

From HT receiver to In on channel a of switch
From Sub to the Out of the switch
Y-Cable from Pre-Amp and Main In Right on Pioneer to in on channel b of switch

I can try another Y cable I guess but there were no issues on the HT side. Sub plays fine when on that channel of the switch

The Y cable is immaterial to function on the HT side (at least in how I suggested the connections), so the HT side working doesn't mean the Y cable or connections are OK on the stereo side.

A photo or sketch/drawing I think is best way to cut to the chase.

 

[whoaru99]

That should work.

If you simply remove the right ch pre/main jumper and replace it with the Y cable, with or without connection to the switch, the stereo system should still work as intended. If the R channel still is no output with the Y in place to me that suggests the Y cable is suspect.

Do you have a multimeter to test the Y cable?

EDIT: Just to be sure, the Y cable is connected like the "Y" depicted by the Right Pre Out / Power In like in the attached illustration?

 

[peterp1]

Post a picture of how you had it. Can't think of any reason it shouldn't work, except a connection error (or a rare occurrence of a defective Y).

Or if the switch was defective and shorting out the RCA -- also very unlikely to happen, but the Y definitely should work, so something must be broken.

OP should unplug the other side of the Y from the switch and test again. If still no right channel output, try the other side (that was connected to the switch) on the amp input to see if that restores the right channel. If so, one side of the Y is broken internally, if not, maybe the Y cable is internally shorted. All very rare to happen, but it's the only possibility. Agree that a picture would help.

 

[whoaru99]

Nope, not normal.

 

[whoaru99]

What about just the Y cable by itself, no connection to the switch and sub?

 

[whoaru99]

Couple more things you could try.

Leave the Y, the switch, and sub connected but unplug the HT receiver from the switch. What happens then?

Remove the switch all together and connect the sub directly to the Y. What happens then?

Did we ever hear what make and model is the sub?