Replacing sound proofing in cabniets

There are formula's for the very thing your wanting to do.

The best investment you could make, would be to purchase the 'The Loudspeaker Design Cookbook'.

If you line the walls of the speakers with a dampening product, that will cut down on externally transmitted cabinet vibes. But, if the speakers was designed with that taken into account, then leave it alone.

I'm surprised, but I shouldn't be,that no one here has mentioned the difference in lining the walls and using a fill of some sort in the cabinet, will have two very different out comes.

Filling the cabinet with some sort of fiber fill, depending on the amount used, will change the QTS of the speaker. Changing it dramatically is possible. The more fill used, the larger a cabinet the driver sees, thus changing the sound.

The more fill used, the higher the QTS will be. The higher the QTS, the boomier the speaker will sound, most of the time. There are a million variables, but this is the
general rule.

Whatever the cost is of the book now, it was $30 when I purchased it several years ago, will be your greatest investment. It's writen in a way that most people can understand the concepts. Not rocket science.

Good luck.

Trelja: Yes Joe, these were the Legacy's we were working on. We just got them finished tonight and are pretty happy with them. That is, considering what we started off with. They are like a completely different speaker now i.e. MUCH better sounding. They still have a "ported" sound to them, but you can't get rid of that without sealing them or using a more advanced bass alignment. This type of problem is especially hard to conceal when the designer crams TWO woofers into a box that is too small for just one of the woofers!!! All of these designs use a box that is just too darn small for the drivers being used, hence the bloated bass that lacks definition. Believe me, this is only a very small part of the problem too. I took pictures of the crossover network before and after. If i can figure out how to transfer these pics from my camera to my puter, i'll forward them over. As i mentioned in what was probably another thread, we were able to go from a total of 122 connections in the pair of crossovers down to 46 connections total!!! All of this by paying attention to how the crossover was laid out on the board. There were NO circuit changes made, so it's not like we changed the parts count in order to reduce the number of connections. Then again, i'm "preachin' to the choir" on this one, so i'll save it for a more appropriate time : )

Steveallen: Most vented designs can be drastically improved by adding damping materials internally. Very few vented designs make use of optimally sized boxes, so adding internal volume via damping material typically helps to reduce the output peak at resonance and smooth the overall response. This is because internal reflections are damped and the box appears to become "bigger", bringing the alignment closer to what the driver would optimally like to see. To top it off, this approach will typically produce increased clarity and definition due to the reduction of the aforementioned internal standing waves being reproduce and less leakage from the ports.

While i do agree with your suggestion to read this book, many people have read hundreds of books and even graduated from schools with a degree. Reading textbooks and passing tests vs knowing how to properly interpret and apply that information are two very different things. This is why we have so many speakers that sound like crap but look so good on paper. Even those that know how to talk the talk end up not knowing how to walk the walk due to a lack of understanding and experience. If this were not true, Trelja and i wouldn't have initially been impressed with what we read and saw about Legacy's, but we were. Wanting to believe and being able to believe are two different things, especially if you are honest with yourself. Sean
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Sean, excellent job on those Legacys!!!

I have absolutely no doubt in my mind that you have taken them at least two levels forward. Your diligence in reducing the number of connections in the crossover would pay enormous dividends, at least to me. You obviously know much better than I how things improved, but if I would venture to guess, I would predict the dynamics and clarity improved audibly, while also realizing gains in liquidity and smoothness at the same time. The audio Holy Grail!

Did you go with the Solen caps in this project that we have talked about in the past? If so, I know you have great sound. I think these caps really get shortchanged when it comes to how good they sound. Full sounding and smooth, again, with great detail. The BEST everyday cap out there(well, actually the thicker film SCR/AXON made on the same line is a bit better, but they're both close). And, did you give those wirewound resistors a shot, Ohmite or otherwise?

I concur with your assessment of the bass alignment. You can only get so much from a box, and that makes me realize why I have been so underwhelmed by the Legacy bass in the past. When you see that kind of artillery, you expect to be blown back. When it doesn't happen, you are left with a lot of disappointment.

I will say that my last encounter with Legacy, at a demonstration they put on locally was by far my best time with them. Again, I found the Focus and the minimonitor to be the best in the line, and even quite good in some areas where a lot of (most) audiophile speakers fall down. My biggest complaint was that the metal dome tweeter was woefully out of date, and its piercing sonics bore this out. They have addressed this since, and I would like to give them another listen.

Their headquarters, in Allentown, are only about an hour from my home, or less.

I also agree with your statements to SteveAllen. While the books(and I have the utmost respect for Dickason's Cookbook) say what they say, I had to say what I have outlined previously goes against conventional wisdom. Like you, I have found that stuffing the ported box often has the opposite effect of producing a more boomy sound. As Fried and Von Schweikert show, it actually produces a less boxy sound. I know I am going to have a bunch of people jump on me here, but I consider the bass of my Fried A/6 Line Tunnel to be superior to my buddy's Von Schweikert VR2.

I agree that we live in a free society and that we have the right to experiment with modifying speakers as much as we want, but if making a change as large as stuffing a vent hole actually IMPROVES the speaker, I contend that it's time to sell the speakers and buy something from a company/designer that actually KNOWS what they are doing! If the woofer section had been (apparently) designed so poorly, how much more well designed could the mid/high section be?!

Barry Kohan

Barry: Neither Joe or myself are encouraging anyone to "stuff" their ports so much as we are encouraging additional damping material inside the cabinet.

Having said that, most vented boxes are pieces of junk and closing the ports completely could quite possibly produce better quality, albeit less quantity of sound. As such, yes, most people would be better off with different speakers than what they have, especially given the majority of under-designed, poorly executed, over-priced products that are currently available. Like most changes in society that have taken place over the years, the public seems to desire greater quantity, even if it is at the expense of quality. As such, the designers / engineers / manufacturers have responded to those desires and given the consumers higher sensitivity and greater extension at the expense of linearity and over-all quality. There are exceptions to this generalization, but that is why they ARE exceptions and are far and few between. Sean
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