To "Y", or not to "Y", that is the question! (1 Viewer)

[Pete Jennings]

I hate to rehash the age-old question of whether or not a 'Y" cable makes any difference on a sub's output, but I will.
After an exhaustive search, much online reading and a whole lot of soul searching I just bought a Velodyne SPL1200 sub from Onecall. I was originally going to choose between the SVS 20-29 PCI and the HSU VTF-3, but after Tom V. AND Dr. HSU kindly recommended placement in the same corner of my room, I realized that I couldn't comfortably fit the VTF-3 there (rear-ported), and that my understanding wife (who has been GREAT while I have been piecing together this system) REALLY didn't want the 20-29 in the corner of our great-room. So, after Onecall received another shipment of "factory re-manufactured" Velodyne SPL1200's, I figured that would be the best compromise for my situation and I pulled the trigger.
I received the sub in perfect condition, the only way you could tell it was a refurb was a slight screwdriver mark where they pried out the defective amp to replace it. I installed it in the recommended corner and calibrated it. So far I like it, I really don't think it was broken in by the previous owner before the amp failed, so it is gradually opening up for me.
I have used a spare three meter or so long RS Gold Series video cable to connect the SPL1200 to my Marantz SR-8200's only sub output. I am toying with the idea of using a "Y" splitter on the sub's stereo inputs. Onecall says Velodyne recommends it, but the only reference on Velo's website is to use it when you have auto on/off problems.
Am I right in thinking that *after* the sub is correctly calibrated, using a "Y" cable with the sub will have *no* output increase? How about increased sensitivity at lower volume levels? I have the sub temporarily plugged into the switched AC outlet on the back of my SR-8200, so I am not really concerned with the auto on/off. I will be purchasing a Panamax 5100 in a month or so, and will plug the SPL1200 into a switched outlet on the 5100 then.
I appreciate ANY information on this. When I grow up and build my next house with a media room, I WILL NOT let size dictate my choices!!!
Thanks!
Pete

 

[Sebastian]

To "Y" is the answer, unless the manual instructs otherwise.
I mean why take a chance?

 

[Pete Jennings]

Well Sebastian, I spent $15.00 on a Monster Y cable, and it did increase the output of my SPL1200 by exactly 6dB. Of course after calibration, the total output level is the same as before - 77dB. After recalibrating, my Marantz SR-8200's sub-out level had been changed from -11dB to -12dB, and the subs output level from 6 ticks to 4. I just installed it and am heading out the door to see the 10 o'clock showing of MIB2, so I won't be able to guage low volume bass response until tomorrow morning.
I hate to shell out the $13.50 for MIB2, but we have a new theater in town and I have to check out the competition!
Thanks!
Pete

 

[Adam Bluhm]

I have a JBL PB10. With the included manual it makes a point (italicized ) to say that if your receiver only has one sub out, then only one connection to L or R is necessary. It makes no difference.
I read on this forum a short while back that someone got a 6dB increase to their JBL sub by 'Y'ing it off to make the L & R connections.
At the moment I only have a single cable. It puts out plenty of bass and I'll go with what JBL tells me for now. It's not baroke, so I won't spend any more money.

 

[Bill Kane]

hi pete, welcome back
As you found, any "Y" increased dB out of the sub is just dialed back again in calibrating. Sub makers, SVS at least, tell us that AVRs sub line-out voltage and sub amp sensitivity to this input signal are well within compatibility so that, in most all cases, only one connection is needed in the sub amp L/R. It's usually explained that the L/R inputs are "summed" going to the sub amp stage, so your Y-connection is fine.
Whether you get "increased sensitivity" to bass at lower volume levels, well, I wouldn't think so. Don't our ears get less sensitive to bass at lower levels, so then listeners will boost anyway to what they find they want.
You have some bad-ass gear there and I have one other comment which I submit in good faith. That is, I've always been informed that a rcvr's rear panel AC outlets are NOT to be used for high-current applications like a 750-watt sub amplifier, but for things like VCRs, tape decks and DVDps. I tried to call up the Marantz 8200 manual to check but cud not load it. (In fact I crashed and had to Restart!)
edit: checked my Yamaha 100Wx5. Rear outlets rated max power consumption 80W.
Here's an informative and long thread on styles of rcvr sub level-sub amp settings this week featuring admin VINCE MASKEEPER
bill

 

[Binh Vu]

I just Y my sub and now its MUCH better.

 

[Phil Mays]

I removed the Y from my sub and went with single wire as I had to "borrow" the Y for another application. I think I could tell a difference. The best way to explain it was it did not seem as "full". I don't know if there were any differences at all as I have a hard time in this area of judgment. Perhaps it is the placebo effect.
Anyway I will be placing a Y back into the sub, just to feel better

 

[Pete Jennings]

Bill, I was a little leery of plugging the sub amp into the 8200's AC outlet. Your statement confirms my suspicion that I need to go ahead and move it. I have a Solus audio rack, and I have used velcro straps (from Home Depot, they look like watch bands) to attach my wiring to the back of the Solus' posts out of sight. Signal cables are run down the back left posts, and power cables (along with ONE optical cable) are run down the back right posts. It takes a little effort to re-run wiring, but I will take care of THAT potential problem before the sun gets any higher in the sky.
Your opinion is appreciated. The "Y" I am using is just a test, logic tells me that the effect will be negated by calibration. When I move the power cable to another outlet, perhaps I will need the Y anyway to increase the on/off response of the sub until I pick up a Panamax 5100 and run it off of a switched outlet.
Thanks for all the replies!
Pete

 

[Pete Jennings]

Ok, final result after an hour of so listening to my reference material? The Y cable stays. It could be the placebo effect or the result of re-calibrating the sub after I installed the Y cable, but I am now *very* happy with the output/sound of the SPL1200 in my system. It is blending so well with my B&W 602S2's that it gives me goose-bumps! (Sorry guys, it's my first sub! ) Music is very important to me, I was very apprehensive at getting a sub that wasn't musical - the SPL1200 is! The term "clean sound" is an understatement.
I will be filling out the warranty card on the SPL1200 now, my ceremonial act of saying "this sub is a keeper".
Bill, I did move the sub's powercord to the surge suppressor, and moved the DVD player's powercord to the switched outlet on the receiver. I do *not* like the DVD player plugged in this way. I am leery of losing my custom settings. I'll be OK with it until I talk my wife into the Panamax 5100 for my birthday.
Thanks again for the assistance guys, I am finally at peace.
(Sorry for all the smileys!)
Pete

 

[Adam Bluhm]

Well, I stopped by Wal*mart after church today. I picked up a $2 Phillips Y connector. If I was happy with it, I'll probably get the appropriate AR Y to accomodate all my other AR Pro Series cables, including the sub cable.
I had a nice listen to a couple of Weezer's new songs before making the Y connection (wonderful rock songs on their new album, Maladroit. ) I then threw the Y in there.
Now's the time where I need to find the best way to describe this. The sub/bass seemed to open up. It had a slight increase in dB, but that wasn't the important thing for me. I just ended up turning the vol. nob down slightly. Anyway, I was very happy with the flexibility the sub began boasting. It sounded open, full, and quick.
Y it is.

 

[Bill Kane]

Pete, thanks for the update.
Temporarily using small, strip-type surge protector for the sub is ok, but unless a storm come over, plugging it into the wall is fine, too. I dont follow your refs to need for "switched" outlets. Usually we work with what we're dealt on the receiver (I get two switched) and for a DVDp that's no different than a wall plug. BUT one wudn't plug a VCR into the rcvr outlet unless it's an ALWAYS-ON type to preserve the VCR clock.
Phil&Adam, I'm glad we are not getting into a sub cable "wire war" Many people just run RG-6 cable terminated with RCAs because for the longer sub run here it's WELL-SHIELDED from any outside radio frequency or AC wire interference. The fact that one hears a slightly more robust sound from the sub using a Y doesnt necessarily mean it's better, just louder, which isn't the same thing.
Pete, I referenced that thread because it addresses how people may experience a sub amp with AUTO ON turning off after a prolonged quiet period during a DVD track. I dont think this is very common, reading the posts. But the overall suggestion is the effort to maximize the voltage going into the sub amp by adjusting the sub amp gain control as high as possible while balancing the rcvr sub-level setting as low as possible.
Vince suggests that a sub amp control may not be a potentiometer VOLUME control but rather at full position it allows full, optimum voltage; in other words, the full voltage is the best path. In reality our rcvr sub level setting may not go low enough to match, so it's a two-handed balancing act. In real-world, most sub amps perform ok with their amp gain control halfway, but I prefer to get it higher "just in case." My SVS sub (internal) amp manual advises to start at the 3/4 position.

 

[Wayne A. Pflughaupt]

Pete,
You got some good replies to your post, but some questions were not fully answered:

Quote:

To clarify a bit, Vince says that with the majority of professional and many consumer plate amps, the gain controls function only as attenuators. In other words, they should be kept all the way up, unless the signal is so strong that it clips the inputs. As Bill noted, typically with this arrangement the receiver’s sub output will be adjusted to a low setting.
Regards,
Wayne A. Pflughaupt

 

[Arron H]

I asked Dan at Adire the "Y" question and he indicated that it really is of no benefit unless your sub gain and receiver sub settings are maxed out. If not, he indicated that that a single input is better.

 

[Phil Mays]

Placebo

 

[Pete Jennings]

Thanks Bill. I am currently using a Panamax DBS-type power strip, so I am covered fairly well. I just ran out of outlets (four) unless I use my receiver's switched outlet. I would rather have a rack-type unit for cable management purposes (personal preference). I also prefer NOT to plug my DVD player into a switched outlet (again, personal preference). My only available option currently is to use the switched outlet on the SR-8200 (the unswitched one is used by my CD jukebox, which tends to lose song titles when powered off too long).
Wayne, I follow your reasoning perfectly, that dovetails with my original suspicions. However, I will leave the Y installed, if for no other reason than to increase the amp's auto on/off performance. Velodyne does recommend this on their website.
All of this is so trivial, it just points out how picky a person I am. I am already planning my "midlife" crisis in a few years (god I'm getting old!). I get to tell my wife "Honey, would you rather me *invest* in a two channel system or buy a convertible and cruise the beach?"
Thanks again.
Pete

 

[John Garcia]

Why ask "Y"?
I have always had my sub setup with a Y configuration because the cable (Monster THX) came with a very nice little Y adapter.

 

[Mark Tranchant]

Most subs two inputs are simply mixed together, with the single input to the power amp stage being half of the left tinput plus half of the right input. This is why a Y gives you 6dB higher output with the same settings: for a processor's sub out signal of x, you get ½x without a Y but x with a Y.

This should not give any real sonic benefit: Binh, I'd like to know in what way your Y-setup is "much better" once you compensate for the 6dB.

There is one effect not yet mentioned here: sub out impedance loading. Each of the two sub inputs will have an input impedance, probably equal. If you use a Y-connector, the impedance seen by the processor's sub out circuitry will be halved: maybe 50kohm instead of 100kohm. With good design on both ends, this should not make an audible difference, but with a low input impedance sub and a badly designed sub out stage on the processor, it might.

From a theoretical standpoint, therefore, I'd go with no Y-connector. You might be tempted to put a grounding plug in the other input: with the simplest mixer designs on the sub inputs, this will have the same impedance effect as a Y but without the gain "benefit".

 

[Bill Kane]

Mark,

You might be tempted to put a grounding plug in the other input: with the simplest mixer designs on the sub inputs, this will have the same impedance effect as a Y but without the gain "benefit".

it's late for me and I am fuzzy: are you meaning this is a positive impedance effect or otherwise? Because I had one, I recently put a Cardas Cap "dust cover" on my unused sub amp RCA input. My existing calibration levels didnt seem to change, and I wasnt looking for it to do so.

bill

 

[Mark Tranchant]

Bill - depends on the circuitry. If the inputs are passively mixed before any active circuitry, then shorting one of the inputs will halve the input impedance of the other - I think. It's been a while since I did virtual grounds and the like.

Most designs have a much higher input impedance than the previous stage's output impedance, so a halving should not be a problem.

Bottom line is that if you don't hear a difference, don't worry about it. Using a Y-connector will definitely halve the effective input impedance of the sub, though.

 

[Phil Iturralde]

I use a "Y" with my Audio Source SW Fifteen and I don't for my SVS 25-31PCi - all based on their respective Owner’s Manual!
Audio Source SW Fifteen - Owner’s Manual

Quote:

Phil