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Old 30th May 2008, 10:47 AM   #1
schro20 is offline schro20  United States
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Default stuffing Mileva: first timer step by step questions

I am getting ready to start stuffing my mileva build this weekend. I have never done my own stuffing on any loudspeaker and wonder whether there is some suggested protocol. For example, I was thinking I will start with no stuffing just to understand what the thing sounds like. Then start with some, then go from there. Question is: is there a way to do this in steps that have the most educational value in terms of learning how various parts contribute (or disturb)?
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Old 30th May 2008, 01:47 PM   #2
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I remember Dave posting a good starting point diagram for stuffing. Search the other Milvena threads. It shouldn't be to hard to find.

If memory serves, You start with stuffing the "points" and line the front and back walls to a point just below the driver.
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Old 30th May 2008, 04:32 PM   #3
chrisb is offline chrisb  Canada
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Contact Dave directly - he has a graphic recommending stuffing locations, but I can't remember if there are pictures of the last actual built pair.

If you think you'd want to play with adjusting stuffing levels, I'd recommend installing cleats & weatherstripping foam to allow for removal of the back panel. With the combination of shallow depth, small driver opening and internal bracing, this box is virtually impossible to get inside once it's fully buttoned up.
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Old 31st May 2008, 10:17 PM   #4
schro20 is offline schro20  United States
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Default stuffing instructions

Actually, I do have the drawings from Dave. I was more interested in the general question of how one might do one thing versus another to learn about the relative impact of various aspects. For example, there is felt on the walls, presumably to avoid standing waves. Then there is the polyfill. What does it do? I presume it serves a different purpose. How does one experientially learn this? What does one listen for?
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Old 2nd June 2008, 11:49 AM   #5
schro20 is offline schro20  United States
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Default no stuffing for now: what to listen for?

So I put everything together last night. I started with no stuffing at all to have some kind of a reference against which to understand the stuffing business.

First observations: there is a LOT of detail in the sound. The loudspeakers vanish pretty nicely. The sound that I hear is inbetween the speakers but not as spatially teased apart as I have heard with other speakers (my main other reference here is a pair of Linkwitz Plutos). I ran a coherent pink noise sound through both speakers. The apparent source of the sound is inbetween the speakers but not as spatially small as I had with the Plutos. What's the right stereo alignment? Right now they are free standing in the middle of the room and I experimented with my own placement relative to the speakers. I noticed that I get better "being in/near the sound" when rotating the speakers towards me, but not all the way. Also I noticed that having a triangle (base between speakers) which is not equilateral, but rather has lesser height I get better "immersion" in the sound (for lack of a better word). When I rotate the loudspeakers to point directly at me the sound is too harsh for my taste.

I tried a whole bunch of different music. One can really hear the difference between the recording qualities of the material. I listened to some Arvo Paart which was beautiful. Some nice David Sylvian as well. A test track of a standard drum set recorded, was surprisingly nice. The amount of bass is surprising, but overall the bass is definitely anemic. (I suppose that's to be expected.) I tried some Madonna (title track from her album "Music"). That definitely did not work.

I supposed I should listen for a few days before starting the stuffing, eh?

So there is felt there in different places and some polyfill in the "tip" of the Voigt pipe. What's the function of the former? What of the latter?
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Old 2nd June 2008, 04:24 PM   #6
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I think you are doing the right thing experimenting with the stuffing. I have done the same to best determine sonic advantages and dissadvantages. Enjoy the process - but don't overturn the screws. Overstuffing could reduce bass too much, understuffing could sound too boomy. But stuffing also reduces the amount of backwave against the rear of the driver which could change the sound of mids and highs. I think it's important to lightly stuff directly behind the driver to reduce this resulting in a less strained or fatiguing sound.

Ultimately for best bass you may need to add a subwoofer. That will depend on your room, your taste and requirements for deep bass. Having such a nice sounding speaker one usually wants to achieve more.

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Old 2nd June 2008, 05:27 PM   #7
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Peter sent me a direct email which was essentially post 1 & 5. Here for completness is what i sent back:

Without stuffing Mileva will have a fair amount of ripple in the lower frequencies and should sound somewhat hollow & coloured in comparison to properly stuffed.

Mileva is a quarter-wave box and as such all the higher, undesirable resonces need to be suppressed as much as possible. The polyfluff in the tips achieves much of this (and once built, it is very difficult to get the fluff in there). The wall lining around the driver also helps suppress these resonances but its primamry purpose is to reduce early reflections. The polyfluff below the driver lets you tune the speakers bass response to your room & your taste.

Never having listened to an unstuffed Mileva i can only make generalizations. It has also been a long time since i have listened to a stock set of drivers. Stock the 127 has a quite noticable peak at 7k which adds some roughness to the top that some people find particularily objectionable. They also have a higher noise floor which obsures some of the low level detail that fleshes out the music and helps provide the clues necessary to create a dramatic soundstage. The mods ameriolate the 1st quite a bit but don't entirely eliminate it, and do a very good job at increasing the downward dynamic range.

Mileva is designed to be placed in proximity with a back wall, and most often with no toe-in so that the wall acts as an extension of the baffle and the listener is off-axis. They do not throw the sound-stage of the same driver in a Fonken, which is likely down to the extremely small diffraction signature of the Fonken. We have yet to play with felt on the baffle or EnABL to see how much Mileva can be pushed towards Fonken in this respect.

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Old 2nd June 2008, 05:49 PM   #8
chrisb is offline chrisb  Canada
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with reference to above post, I think Dave's last sentence is meant to say

"we have yet to play with Felt or EnABL on the baffle to see how much Mileva can be pushed towards (the original) Fonken in this respect."



From my own extensive listening to several examples of each design in a variety of rooms/systems, IMHO there is definitely a trade-off between bass extension and weight (Mileva wins here) and imaging/bass "articulation" (Fonken). Due to the substantial difference in dimensions and profiles between these 2 designs, I suspect that while further baffle treatment could elicit some benefit for each, it's not likely to close this particular gap.

Compound the difficulties in describing or assessing these kinds of differences without an experiential reference, with system / room synergy (or lack thereof), as well as individual expectations and tastes, and things can get murky .
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