On the verge of crying - longer post

Milsivich

Here is my post from about 2 months ago:

---

I have been troubleshooting this problem for 4 months now, and I have finally established one of two things; either the MicroPRO 2000 is the biggest ripoff of all time, or I have received 3 sets of defective parts in a row.

My Setup:

Parasound NewClassic 2100 pre-amp
Parasound NewClassic 2125 amp
Pair of Polk LSi9's
MicroPRO 2000
Sony turntable
laptop (connected with HRT Music Streamer II, an offboard DAC that hooks up to the USB port)

The Problem:

At low volumes, as low as 8 out of 40, a HORRIBLE thumping noise comes out of the sub. It sounds exactly like the sub is being maxed out, only its volume level isn't even near that of the "room optimizer" setup sequence. It happens on any sort of beat or kick. This effect is extremely obvious to even untrained ears. More minute details are they even on prolonged tones there is an unevenness or a quaver about the sound, and also that the beating of the subwoofer is behind that of the speakers.

Troubleshooting:

I'll lay out everything I have tried, from the top of my system to the bottom. I tried changing the source by playing the same song from my laptop (both with my offboard DAC and a headphones jack to the "mp3 in" feature of the pre-amp) and from my turntable, no change. I tried different cables, including some really nice Monster cables. I hooked up the source directly to the sub (skipping the pre-amp). I tried hooking the sub into the "main out" instead of the "sub out." I have changed the physical location of the sub, even holding it in the air with my hands while it played.

This first MicroPRO 2000 I got I returned because of this problem. The second one I received also had the problem, at which point I personally replaced the amp and the speaker cone with new replacement parts from Polk. They all had the EXACT same problem.

The pre-amp was recently at the top of my list of possibilities, but the problem persists even when I hook the source directly to the sub. Also, other subs sound find from the same pre-amp, as do the LSi9's, which dip almost as low as the subwoofer and sound absolutely delightful.

---

Update:

Because of my troubles, the amazing Polk Audio customer support (no sarcasm here; even though this is probably the longest and worst experience I have ever had a with a product in my life, they have actually been very great) upgraded me to a MicroPRO 3000.

When I first unwrapped the box I was feeling a little bit hopeful. I turned set it up, turned it on, and hit the "room" button.... aaand nothing. I tried plugging it into a source, and nothing. At this point the whole situation was almost laughable. Because I ended up taking one of the 2000s completely apart and putting it back together (including the driver) I decided I would go ahead and try and fix it myself. Sure enough, one of the wires connecting the driver to the amp had come undone (maybe during shipping....?) so I went ahead and plugged it back in. Success! I got sound.

Well, I went ahead and ran the optimizer, and once that was done I went about "breaking it in." Because I am now completely paranoid about anything and everything that could POSSIBLY go wrong, I played the sub at very low volume levels (volume set at 5/40, system below a normal speaking level of volume) for a few days. I realize this is probably not loud enough to actually break a driver in, but whatever I was paranoid.

So, finally I decided to turn it up and hear it speak. When I say "turn it up" I mean 10/40 instead of 5/40. I put on a track with some bass and slowly turned the volume up, and wouldn't ya know at about 80dB--30% preamp volume--that same damn thumping showed up. These are volumes that even a cheap sub could handle.

Honestly, at this point I don't even know how to move forward. It seems as though I have done everything that can be done, and I have gotten all the help in the world, but there is still something horribly wrong.

Thanks for reading my wall of text. Any and all advice is welcome.

Milsivich

I got a recording of the sound. I don't have any good recording equipment, so this is just the microphone on my iPhone, which probably drops off really bad at lower frequencies. Also I was only running sound out of my sub, which is why you don't actually hear any music. The specific sound making the sub make this sound was the bass drum on a track by Augustana, a generic rock band.

Memo.m4a.zip

IRLRaceFan

I have two microPro2000's and have had similar problems, but at higher volume levels and only when playing music with a Denon AVR-989. At that time I only had one hooked up (no Y-splitter) and would get the problem with either sub, but one always had it a little worse.

I switched out the Denon with an Onkyo TX-NR1008 and now run them both (9.2 config). On occasion I get an issue, but it's usually when my daughter is playing some Hip-Hop with heavy bass at high levels.
I came to the conclusion that the Onkyo just handles bass better than the Denon; which sucks in a way, because I feel like Denon does music better overall.

Don't know if this helps at all, but I would try a different AVR or processor.



A lot of people say the microPro line is great for music. I don't really know because I've only owned Polk subs, but I suspect there's better out there. I plan to eventually try an SVS sub, but it's low on the upgrade list.

Good luck!
Shaun

dudeinaroom

I am not sure if the micro pros have on/off/auto switch, if they do and you are using it in the auto mode it could be that the signal level is not enough to kick the amp on, and kicks on when the bass hits as there is more energy in the lower audio spectrum. IF you are running it this way, try running it in the on position for a while and see if it goes away. You might end up having to turn the sub on and off for your listening sessions. I have had this problem with a sub in the past at low listening levels. Good luck

F1nut

Have you tried borrowing a different brand of sub to see if you still get the thumping noise?