9962 disappoints NO MORE!
Posted 11 June 2010 - 09:03 PM
One of the most disappointing boxes I can remember was my Prosonic PQR-9962. I expected great things but received a box that seemed to have,in effect,fake tweeters. The highs on this box sounded really flat to my ears. Given my proclivity towards excessive highs,this box ranked pretty far down on my list sonically speaking.
Having learned of the effect tweeter capacitors have on sound,I decided to experiment. Simply put,a tweeter caps rating has everything to do with the amount of sound coming from your tweeters.Before beginning my experiment,I decided to check the pair in my 9962 to see if they were any good. This box has caps with a rating of "10uf ". I replaced them with caps of the same value and the box sounded the same. Though it doesn't speak well for its designer (in my mind),this told me my boomer was performing as it was originally intended to sound.
10uf black cap came stock on the 9962
6.8uf blue cap was my first experiment
Then I replaced the 10uf caps with 6.8uf caps. To my surprise,much more seemed to be coming from the tweeters as the highs came to life. The difference was pretty significant. However,I was hearing harshness on some vocals and even experienced some actual ear pain at times. This told me the tweeters were being asked to handle too broad a frequency range for them to reproduce accurately introducing unacceptable distortion.
At this point,I had a dilemma. The tweeters with "10"s were lifeless.The tweeters with "6.8"s were obnoxious.Unfortunately,it appeared really difficult to find bipolar caps with a rating between these two values.I thought I might have to settle on one or the other. Luckily,I eventually found caps with a value of "8uf " at a website selling parts for home stereo speakers. I ordered a set of these. While waiting for them to arrive,I did some more listening to become thoroughly familiar with the boxes modified sound.
When the "8uf"s arrived,I was amused by their different appearance. The caps I was used too seeing were barrel shaped.These were a really cool orange color and a unique oval shape. I unsoldered the "6.8uf "s and soldered in the new "8uf"s. WOW!!! Now I was getting the increased presence from the tweeters without the harshness. I'm now LOVING the PQR-9962,a box I had once written off as merely a classic looking bass machine.
What is somewhat bizarre is that I've been told differently here in the forum by someone who is more educated on such issues. Supposedly I should be getting more highs from caps having higher values. I personally got into collecting blasters to find older model boomboxes which had brighter sounding highs so I don't know quite what to think of this disparity. Resolving this issue really isn't important though. The reason for my post is to tell you that I now LOVE this boomer! The Prosonic PQR-9962 sounds much different with its stock caps replaced with those of a different value. As for what values to use,I can only say do your own testing.To my ears,mine sounds much better and has a brighter more lively sound. A box I once had written off as eye candy is a favorite sounding unit now. Its output now matches its formidable classic looks!
Posted 11 June 2010 - 09:18 PM
Posted 11 June 2010 - 10:43 PM
You may be reading too much into the capacitor "value." The difference you are experiencing is almost definitely due to the improved quality of the capacitor. First off, the first 2 capacitors are bi-polar electrolytics. They are essentially (2) polarized electrolytic caps back to back. The big orange one is a much more expensive film capacitor and not a bipolar. It is also likely a much higher voltage one (my guess 100 - 250v). High voltage film caps (the best are polypropylene or Styrene) most definitely is an improvement over teeny electrolytics. You can improve performance even more with polystyrene but we are talking $20-$30 per cap. High voltage caps are known to improve the sonic quality of the signal although no one knows exactly why, there are some guesses. It is no coincidence that the M90 utilizes large film caps like the one you just installed. In fact, it is the only boombox thus far where I've seen the manufacturer willing to splurge on the cap.
Posted 12 June 2010 - 04:01 AM
Posted 12 June 2010 - 05:40 AM
I must sat I have never seen such a large capacitor of that type. I'm now tempted to look for some given what you and Norm have said. I will wait until I find some new tweeters though.
Posted 12 June 2010 - 09:43 AM
Graet job fixing her up.
Posted 12 June 2010 - 11:35 AM
If you got those film caps for a buck, you got a steal. Please share your source. Also since you seem quite interested in the audio effects of the capacitors, may I suggest you visit the following website. I found it one of the best and well written descriptions about capacitors and their effects on audio quality. Also, does an excellent job of describing ESR, etc.
For an idea of how the capacitor value affects the tweeter crossover point, see the following charts. C1 is the capacitor for 4 ohms and C2 is the capacitor for 8 ohms. Forget L1 and L2. Those are inductor values if you want to build a low pass (or both if you want bandpass) crossover.
Posted 12 June 2010 - 01:20 PM
Posted 13 June 2010 - 07:09 AM
Posted 13 June 2010 - 09:46 AM
Ok, it's not exactly that simple because what it cuts is 6db/octave using the data quoted. Use the other chart to come up with 12db/octave crossover point.
Jovie's experience seems to be the opposite but I wonder if it's due to the quality or functional condition of the capacitors.
Posted 13 June 2010 - 06:58 PM
I go on practical experience and I'm totally convinced I'm in an alternate universe on this. For another example I remember the shop putting 8uf caps in my Lasonic LPC-990 and I could barely hear the tweeters.I put a set of 4.7s in and there was definitely more sound coming from the tweets. Then I replaced them with 3.3ufs and they're really putting out sound! I have a thing for bright sound and I don't believe that less sound going to the tweeters is going to effect that....so I don't know what to think...
Master Z and Mellymelsr are saying the 9962 with stock 10uf caps has prominent highs which is also DEFINITELY not my experience... until I put in 6.8s and was knocked down by the tweeter output.I had to back these off to the 8ufs installed now just to tame the harshness of the sound. At the risk of appearing to yell,"CAN LESS SOUND FROM TWEETERS MAKE YOUR EARS HURT?" These are the honest closely scrutinized results of a person who loves bright highs and lots of sound coming from tweeters.I have a number of experiences like this so I'm beginning to think I'm nuts.
Here's a link to the caps you doubted could be had for anywhere near a buck:
http://www.speakerwo... ... /capm8.htm
I'm seeing .85 cents. Please confirm this as I have a feeling that they're really $10.00 a piece because...well... everything seems upside down in my world. I wouldn't doubt it as science and the testimonies of 3 reliable people don't reflect my real world experience with my boomboxes. Maybe I just think less is more which WOULD explain why I'm not rich...or am I and don't realize it? This is really freakin' me out!
Posted 13 June 2010 - 10:21 PM
I don't doubt your experiences. All I'm saying is when experimenting with various values, stay consistent with brand and product line and you'll get a better idea. If you were to compare a Milwaukee 1/2hp gear reduction drill, to a Craftsman 3/4" drill, and then a 1hp Black and Decker drill and your conclusion is that the lower the HP, the more powerful the drill, you might be right and wrong at the same time. But if you were to test a 1/2hp Milwaukee to a 3/4hp Milwaukee to a 1hp Milwaukee, your results might be 100% upside down once a gain. There is more to a capacitor than just the uf rating. Electrolytic caps are notorious for values that can be up to 50% off from the posted spec. Their tolerances are all over the map. Film caps have much tighter tolerances. Also, capacitors have something called ESR, which is short for Equivalent Series Resistance. It is like a resistor in series with the circuit. Obviously a low ESR cap would permit more signal strength to pass than one with a high ESR, even though the farad capacity is the same. Then there is inductance, which varies with the frequency of the signal passed. That is another curve ball.
So in short, experiment with same brand vs same brand, with the same product line, i.e. FH to FH, etc. Then your results might be more meaningful. Just my humble opinion.
Posted 14 June 2010 - 04:12 AM