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9962 disappoints NO MORE!


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#1 Jovie

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Posted 11 June 2010 - 09:03 PM

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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.

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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.

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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!

#2 redbenjoe

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Posted 11 June 2010 - 09:09 PM

nice going, jovie :thumbsup: :yes:

#3 MasterBlaster84

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Posted 11 June 2010 - 09:18 PM

Nice work Jovie your persuit paid off, way to stick with it. There may be a lesson in this for other boomers too. :hmmm:

#4 Superduper

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Posted 11 June 2010 - 10:43 PM

Jovie.

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.

#5 Jovie

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Posted 12 June 2010 - 04:01 AM

That's an interesting observation about the increased quality and is something I hadn't considered. Whatever the different effects of the cap values,all I can say is that (for what ever reason) these 8uf 100v film caps are a great match for the 9962. The highs are beautiful now.There is a big difference from the stock issues and I recommend anyone make this modification.My orange ones cost only around $1.00 a piece as I remember.

#6 gld1307

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Posted 12 June 2010 - 05:40 AM

Nice one Jovie. Really nice box too.

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.

#7 Master Z

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Posted 12 June 2010 - 09:43 AM

I'm happy you got your box straightened out. I remember all the posts regarding the 9962, you would chime in saying the sound wasn't there. I would think to myself this guy if F'ING crazy! It's one of the boxes I don't ever crank full treble. :-D
Graet job fixing her up.

#8 Superduper

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Posted 12 June 2010 - 11:35 AM

Jovie. I have noticed before that you've posted the substitution of varying capacitor "values" noting the effect of that substitution. Yet, each time, it seemed you weren't consistent with brand, size, voltage, etc when making that substitution. There are differences. Even electrolytics have varying types and characteristics. Each manufacturer has many many lines of capacitors too. For example, Nichicon has their audio grade Muse line of capacitors and Panasonic FC's are known as good ones for the audio signal path. Merely just throwing any old capacitor in there, one from Radio Shack and another from some other unknown brand may have very different results. I just think that when you are comparing capacitors, try sticking with the same brand/line/voltage for a better comparison. Otherwise it's really hit/miss and trial by error and may have no true correlation with the "value" effect.

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.

http://www.bext.com/replace.htm

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.

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#9 mellymelsr

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Posted 12 June 2010 - 01:20 PM

...great job on the 9962...but I must say that I don't turn my treble up all the way on mine either because it is very strong...and has a very balanced sound. I am glad you were able to get yours the way you like it because I love mine!...I hope you have years of enjoyment with her... :-D

#10 muto

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Posted 13 June 2010 - 07:09 AM

Offtopic: The Hitachi TRK-8190 has 1uF capasitors. Replaced them with 6,8uF and now i can hear them. Very good and cheap update if you want to activate the tweeters :).

#11 Superduper

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Posted 13 June 2010 - 09:46 AM

It actually IS relevant. Because electronics theory suggests that higher value caps will permit a greater freq range to pass to tweeters. Which is what you are hearing. The 1-uf's cut off the frequencies so soon that ALL frequencies below something like 15khz to 18khz will be cut from the signal to tweeters (can't tell, it's off the chart). Going with the 10uf's instead will allow frequencies down to 4khz to pass (4ohms) and 1.8khz (8ohms).

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.

#12 Jovie

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Posted 13 June 2010 - 06:58 PM

Superduper-When you learn as you go,you do the best you can.I believe most people just learning would assume that the ratings on caps were consistent from brand to brand even if they're not. I'll have to trust you that there is quality variances. Even so,I haven't bought any one particular brand from box to box and my results have been consistent. :huh:

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... :huh:

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? :huh: This is really freakin' me out!

#13 Superduper

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Posted 13 June 2010 - 10:21 PM

I've bought from speakerworks before -- seems to be good company. Those 8uf mylars are pretty cheap. You should stock up. I might buy some myself. 250volt ones (or higher) might even sound better. I'll see what else they have. Since shipping adds a significant amount, buying 2 cheap caps won't be cheap after you factor in shipping unless you buy enough stuff to dilute the cost. A quick check at Mouser.com for 8.2uf 100v caps shows a low of $1.60 for their cheapest ones when purchasing a minimum of 650, to a high $$ 25.12 each, minimum order of 73. But of course these are polyester and not mylar. The point is... 85cents ......it's cheap.

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.

#14 Jovie

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Posted 14 June 2010 - 04:12 AM

I had thought that boomboxes were not high fidelity enough to resolve the differences in sound quality that you would experience with different brands/materials when it comes to caps. I was once into high end stereo and burned out on it,thankfully before having spent too much money.Now I'm into shrill tinny sounding lo-fi tweeters.Some of the higher distortion ear splitting boxes I am very fond of.Go figure....