800i tweak
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ncstatesman
Posts: 145
Can someone comment on this?
This is pretty interesting:
http://www.hometheaterspot.com/cgi-bin/ubbcgi/ultimatebb.cgi?ubb=get_topic&f=85&t=000037
Here's what this guiy did:
. . . "I replace the stock xover in the 800 with the xover from the 3000 sat and the improvement was amazing. Most complaints you hear about the 800 is that the midrange is muddy so I decided to tweak it. The clarity, separation, transparency and detail were improved. The speaker is now a Tapered Cascade Array and works great. The modification does not require any permanent alteration to the speaker so no warranty issues. The only problem is that now the sound is so clear and transparent that you can really tell a bad recording from a good one. "
-in the long run, would this harm the 800i ?
This is pretty interesting:
http://www.hometheaterspot.com/cgi-bin/ubbcgi/ultimatebb.cgi?ubb=get_topic&f=85&t=000037
Here's what this guiy did:
. . . "I replace the stock xover in the 800 with the xover from the 3000 sat and the improvement was amazing. Most complaints you hear about the 800 is that the midrange is muddy so I decided to tweak it. The clarity, separation, transparency and detail were improved. The speaker is now a Tapered Cascade Array and works great. The modification does not require any permanent alteration to the speaker so no warranty issues. The only problem is that now the sound is so clear and transparent that you can really tell a bad recording from a good one. "
-in the long run, would this harm the 800i ?
Post edited by ncstatesman on
Comments
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Sounds like HUNTER. I guess he's posting on another forum. If you do a search in the archives, you'll find the very extensive thread on this topic.
Aaron -
the archives at the Spot forum? Ok.
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No, look for "your opinion please" on the "Your Opinion" forum. About 3 pages worth, last time I checked.
I did more than my fair share of "opinionating" on that thread, and I don't wish to get into it again. There's nothing wrong with trying it, if you don't mind possibly blowing the money for the crossovers: I don't see how it could harm anything. The thing is, the 800i's are a "known quantity"--a nice, good-sounding, well-engineered speaker". Unless you can obtain detailed specifications for the drivers in the 800i and in the 3000 sats, then the result of swapping crossovers is impossible to predict. Making a crossover that works is easy--Optimizing a crossover for a particular speaker system can be rather complicated. I like to think that Polk gives some thought to stuff like that.
Polk says that swapping the crossovers is a bad idea, and I can't imagine how they could justify the price difference between the RT55i's or 800i's and the 3000 satellites if the only significant difference was the crossover. Maybe they've got me snowed.
Hunter thinks it sounds good, and that's fine. I have my doubts, so I won't be trying it, but to each their own!
Jason -
I'm the one that replaced the crossovers and they do sound great. As we all know sound is a subjective opinion, that is why I posted in the opinion forum rather than the technical forum. I doubt that polk optimizes all components of a mid price speaker. If they did then it wouldn't be a mid priced speaker anymore. The 3000 xover uses better components (mylar) than the 800 xover. If you think that a speaker manufacturer optimizes all components for a given speaker all the time then check out NorthCreekMusic.com and check out the xover upgrades they have for the B&W, and NHT sub zero's, both of which are true audiophile speakers. Now you say, they have probably done extensive testing of their xover with those speakers and tuned it to be superior to the manufacturer xover. I am sure they have done extensive testing and possibly developed a better xover but by your rational this would not be possible because the manufacturer would have built the optimum xover that could not possibly be improved. Now, I don't have expensive testing equipment and extensive knowledge in electronics or frequency charting but don't you think that maybe, just maybe this could work, and if not then your only out $120.00 for a pair of xovers.
Here is a statement from Termpro:
"I've found that the crossovers packaged with some component speaker systems aren't so hot, since speaker manufacturers often throw in a device that's made of cheap components and that can lead to headaches. Using "canned" crossovers sticks you with the crossover frequency and slope chosen by the manufacturer, of course again, less flexibility."
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As I mentioned in the other thread, I think an interesting experiment would be to upgrade the current RT800i crossover with better components (mylar caps, etc.). This would retain the character of the crossover (2-way) while improving it. The question is how much improvement will you gain? Probably not as much as HUNTER's mod, but you won't lose the bass. If you're really going to go to that trouble, I would upgrade the interal wiring as well. I think the net effect of those two upgrades would be substantial. That's enough BS for me for one night.
Aaron -
Yes, it might work. Actually I'm very interested in your findings.
You're taking what I'm saying the wrong way: I'm not saying the speakers or the crossovers are perfect or can't be improved. I am saying that the crossovers in the 800i's are designed to work in the 800i's by people who know the specifications of the drivers involved. The 3000 sat. crossovers are designed for those speakers (albeit with better parts, and possibly more sophisticated tuning).
All I'm saying is that I think the drivers in the two different speakers are significantly different enough that the crossover for one speaker is going to be LESS optimized for the other, than the one that the factory installed.
I don't have extensive experience in electronics, either. You quite possibly know more about it than I do. I have dabbled in speaker building and crossover design, on a limited basis, and I'm just giving my viewpoint on the issue. Since you've actually tried the swap, you're in a better position to talk about how it sounds than I am. As you said, though, the sound is subjective, and I'm just saying that, for my $120, I'd rather try some other "tweak".
I was actually hoping someone from Polk would jump in here and offer some details about why this would, or would not be a good swap, but they may avoid this for one reason or another.
And I agree with Aaron, above, about upgrading crossover components.
Good luck with your experiment. As I said, I'm genuinely interested in what you find out. That's ALL I'm going to say about this!
Jason
"Fairwell! Peace be with you! May the forces of evil become confused on the way to your house!"--George Carlin -
Hey Jcaut,
I appreciate your opinion and your apprehension about trying the swap. I felt that it had the potential to give me a better sound more so than a higher end cable or bi-wiring for the money. I don't mean to snap when some one doubts this but I have been slammed for even attempting this, which makes no sense, so I may be on the defensive. I'm not suggesting that anyone go out and try this but If someone else had done this I would be interested in the findings. I talked to polk tech support and as I suspected they don't recommend making any changes to the speaker. If you look at the 800i cross over its not perfect for the drivers they could have used better components but then again we would be paying more for them.
Aaron,
I have not sacrificed the bass output with the new xover. I can either remove the 80Hz HPF completely or install it on a single 6.5 as I am doing now. The bass can be the same with the new xover as it was with the old if I choose. -
Sorry if I opened a can of worms . . . I need to print these threads out and study them and decide if it's worth it. I guess, part of the fun of HT is trying new tweaks and learning more about how you r system works . .
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In your current configuration your are sacrificing bass output by only using one driver for the bass. Did you notice a performance decrease with the HPF completely removed? I think you answered this question before, but I forgot. If you don't notice a degredation, then this is the way I would run them. If you do, then it's a sound quality vs. bass output tradeoff. In that case it would seem like your current configuration is the best compromise.I have not sacrificed the bass output with the new xover. I can either remove the 80Hz HPF completely or install it on a single 6.5 as I am doing now. The bass can be the same with the new xover as it was with the old if I choose.
Aaron -
Aaron,
My current configuration does limit the bass since only one of the 6.5s is running below 80Hz. I know that with the HPF completely removed the clarity is superior to the stock 800i while the bass remained the same. I have only had these tweaked for a short time and I like that I have the ability try different configurations within the same xover. I haven't had the time to do enough critical listening to evaluate the differences between them. As soon as I get some time I will post back with my findings. -
Cool. I'll be looking for the follow up. Thanks.
Aaron -
I have a question: In the 800's in stock configuration, the 6.5" drivers are wired in series, correct? I'm having trouble visualizing how the 3000 crossover would accomodate these two drivers with separate crossover points, without causing impedence issues. It can't be done if the drivers are wired in series; They function as one. Can somebody explain this to me?
Jason -
Jcaut,
You are correct the 800i 6.5s are wired in series. At high frequencies the impedance values actually increases. The xover utilizes resistors and capacitors to equalize the impedance. There are other ways to compensate for deviations within the xover design. Basically these attributes are built into the design of the xover. The 800i is a 2 way xover because the 6.5s are in series and are both producing the same frequency. The 3000 xover is a 2.5 way because the 6.5s are not wired in series and utilize similar frequencies but have different LPFs. The 3000 is not treating each of the 6.5s as true individual drivers because they share a significant overlap of frequency. A 3 way design would be used with a tweeter, midrange, and woofer that all utilize their own specific frequencies. There should be no significant effect if any with removal of the 80Hz HPF cap because it is ahead of the inductors. -
The 3000 is not treating each of the 6.5s as true individual drivers
I disagree with that. If they have different LP frequencies, then they have to be treated as individuals, regardless of whether or not there is overlap in the frequency range.
This is what I'm getting at: If the nominal impedence of a driver is a certain value, then two of them wired in series will be double that value. Actual impedence varies with frequency, as you say, but if the drivers in the 800i are wired to the crossover in series, and the nominal impedence of the speaker SYSTEM is 8 Ohms, then I would guess that each driver, taken individually would have an impedence of about 4 ohms. On the other hand, if the 3000 satellite drivers are wired to the crossover as individuals, and the nominal impedence of that speaker SYSTEM is 8 Ohms, then it to me it seems that the nominal impedence of each driver should be 8 Ohms. Now, I realize that the actual impedence of a speaker system often varies considerably from the rated value. That might be what's happening here. But, if I'm correct (and I'm not saying that I am) then when you wire the 800i drivers to the 3000 crossovers individually, the crossover points are going to be significantly different than intended. Your 80Hz HPF would become a 40Hz HPF, and so on.
It goes back to not knowing the specifications of the drivers involved. Just wondered if you had thought about it that way.
Micah...Jay...Paul..?? Someone jump in here and tell us how different, electrically, these drivers are!
Jason -
Jcaut,
You are correct I don't know the driver specs for the 3000 sats and would really like to get that information. I am making the assumption, I could be wrong as well, that the bi product of the tweak is yeilding 8 ohms and that the frequencies close. I am not to terribly worried about the ohms because by denon will handle 6 to 16 ohm speakers and has a protection circuit. I am glad you raised this question and hope that some comes forth with the information on the drivers. -
Don't forget that the RT3000p drivers are different than the RT800i drivers. I suppose they could also pose a different impedence.
Aaron -
Aaron,
I think that is what Jcaut is referring to. The question, which is a good one that I had not thought of, was that since the xover was designed for different drivers that impedance and frequency specifications may be altered. It would be great if someone would come forward with the driver specs; I doubt that Polk would release the information. I know that from speaking to polk that the rt55i and rt800i 6.5s look alike but have different part numbers so I would assume that they are different in some way. The rt3000p sat 6.5s are obviously different by looks alone to what degree these drivers are different is the question. I know the sound is better with the new xover and that my receiver can handle some variation in the Ohms but I would like to know what the Ohms and frequency of this setup is producing.
