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View Full Version : PS1400 Performance Series subwoofer - low output issue



Slare
01-10-2010, 08:01 PM
I recently came into a mini-batch of some Performance Series gear, part of which was a PS1400 subwoofer which was advertised as non-working.

However, the sub works, just not quite right. It produces sound using the LFE and speaker level inputs, just not nearly as loud as I would expect. The sound it produces is good, both the LFE & LE level pots work, as do the crossover switches. It's just at max output I'm getting what I'd expect from a 25 watt amplifier (and yes I do have one so I know). Think 20db below reference, similar to what a normal person might watch regular TV at. Loud for constant listening, but nowhere near loud.

The sound is not bad, the woofer is not bottoming or distorting. It is noticeably moving maybe 1/3rd of peak excursion. The indicator lights work properly showing green and red.

Is this normal? Does the PS1400's inputs have extremely low sensitivity?

The only testing I've done so far are using a t-amp to the high level inputs, and a ipod (via headphone to RCA adapter) to check the LFE input. Both produce similar output. I use the ipod method to check powered subs and it has always worked (prolly checked 50 subs this way without a problem).

Soon, I will hook another 500 watt plate amp directly to the woofer and will visually inspect the amp at the same time. But I'd like to ask for any tips.

PS - the friggin' thing is heavy. I'm thinking mine might be stuffed full of gold bars or something. I pretty much ruined my cheap ikea table just setting the thing on it. Whoops.

http://img94.imageshack.us/img94/4126/ps1400.jpg

Slare
01-11-2010, 09:01 PM
Hooked the sub up to another plate amp tonight and it is definitely the amplifier. I just find it odd that the amp seems to work 100% as it should, just with greatly reduced max power output. Can't say I've ever heard of an amp failing like that.

Regardless, after having listened to it I am just not impressed enough with it to be worth the hassle of repairing this one and finding another PS1400. I think my tastes and sense of value are better suited to getting a modern sub that can pull double duty low end and LFE. I realize this is likely a SQ sacrifice in one way or another but life is full of compromises...

Allanvh5150
01-11-2010, 10:26 PM
Hooked the sub up to another plate amp tonight and it is definitely the amplifier. I just find it odd that the amp seems to work 100% as it should, just with greatly reduced max power output. Can't say I've ever heard of an amp failing like that.

Regardless, after having listened to it I am just not impressed enough with it to be worth the hassle of repairing this one and finding another PS1400. I think my tastes and sense of value are better suited to getting a modern sub that can pull double duty low end and LFE. I realize this is likely a SQ sacrifice in one way or another but life is full of compromises...

If the amp is class G or H and the power supply is not increasing in voltage as it should, the volume may be very low. Although I have never seen this happen I suppose it could.

Allan.

Eaulive
01-12-2010, 12:10 PM
If the amp is class G or H and the power supply is not increasing in voltage as it should, the volume may be very low. Although I have never seen this happen I suppose it could.

Allan.
The supply won't affect the gain of an amplifier, instead if it does not track you get chopped waveform and distortion when the output level exceeds the supply voltage.
My best guess on this one would be something defective in the input stage or the -FB loop.

Don C
01-13-2010, 07:16 AM
The amplifier in a PS1400 is not set up the same as a typical subwoofer, there is no extra gain available in it. It's normal to run with the gain control turned all the way up, unlike a typical sub where you would usually have the gain control below half volume. It shares this trait with the older B212 subwoofer. Depending on the other components in your system, you might also have to adjust the subwoofer output to +10db at the HT processor or AV receiver to get normal output level from the PS1400, this is compensate for the "LFE bug" Do a search, there's information about this available at AVS forums and elsewhere.

Slare
01-13-2010, 02:43 PM
I've hooked an ipod up to the LFE input via 3.5mm to RCA adapter. This is what I've always used (portable, easy) to test subs. The driver gets some excursion but the volume is relatively low. I have never found this approach unable to provide a high enough input signal to max out a sub/plate amp. Usually it'll drive a plate amp into clipping at the nominal setting or a little more (12 o'clock).

I have a baby 25 watt Jensen plate amplifier and the PS1400 amp produces about that same level of sound. Not at all loud, certainly not 400 watts into a 14" driver loud. Yet I know from the other plate amp the driver is fine. Not good for deep bass but very punchy at 40-50Hz (as I somewhat expected).

Driver VC checks out at 6.2-6.3 ohms, and there is no coil rub. Seems to be the amp.

Can anyone confirm the LFE input level that is required to hit max gain? Or for that matter, the wattage into the high level inputs that are required for max gain?

rdgrimes
01-13-2010, 04:39 PM
Can anyone confirm the LFE input level that is required to hit max gain? Or for that matter, the wattage into the high level inputs that are required for max gain?
I run the LFE level at 12:00 and get "0" boost when I run auto-level setup routines with my Yamaha AVR. That means it's producing reference level LFE at "12:00". The LF level runs at "0" and actually gets rolled off a tad in the EQ. (placement issue) IOW, if you have to ask, the output is too low.

Slare
01-30-2010, 01:36 PM
For what it's worth, I just picked up a pair of PS1400's and have found that the problem really was with my ipod input testing method combined with unrealistic expectations when I had the driver hooked up to a different plate amp. I think there must be some level control in place in the amp to protect the LE14 from high LFE input - I suspect there may even be some level of subsonic filtering. Overall the LE14 is just not very capable in a LFE function. I was warned of this, I just expected a little more from it, I guess.

However in the docked configuration functioning as the bottom end of a PT800 stack, it actually functions just fine. So now I have three PS1400's. Such a mess.

I guess the lesson learned here is if you are checking a PS1400 out don't rely upon the ipod testing method to check a PS1400 unless you can do the same to a known-good unit and compare the output. It (ipod) just doesn't put out enough juice to drive the low level inputs hard enough. I'm not proud of this whole ordeal, but I have used the ipod method to check tons (and I mean tons) of other powered subs and it has always worked fine. The PS1400 amp is just an odd duck.

Oh, and btw with the regular level gain all the way up, the PS1400's continue to gain volume well past a 100 watt high level input. So it seems impossible to get max output out of the amplifier using anything less than a 100 watt amplifier. Seems logical it would be designed to take a 250w input to get max output. I am running the level input flat but wanted to check what the PS1400's were capable of. Running a typical (100w) AVR won't drive the PS1400's to full tilt!

I'm quite confident that some AVR's won't generate a high enough sub output signal to drive the PS1400 amplifier to full tilt, either. This may have been intentional somewhat to protect the LE14.