Pensil Pics, lets show 'em!

[paul burchell]

How do you tease it dave

 

[planet10]

2 hands.

Just keep pulling it apart, repeat over & over & over again.

dave

 

[Bigun]

I've used the batts before and it seems to work fine - the stuff I had was self-supporting and maintained a uniform density but had I teased into to fluff it might have gotten clumpy.

 

[planet10]

I've used the batts before and it seems to work fine - the stuff I had was self-supporting and maintained a uniform density but had I teased into to fluff it might have gotten clumpy.

Application dependent. For the Pensils, it should be well teased and fairly uniform. Also leaving it as bats means you can't change the density of the stuffing.

dave

 

[Stresss42]

Steve,

It doesn't look you have teased it at all. It is intended that you have a homogeneousfluff, not a bunch ofbats.

dave

Ok thanks Dave,

looks like them backs are coming off again ! Less dense dacron improves mid / top end ?

 

[Stresss42]

Application dependent. For the Pensils, it should be well teased and fairly uniform. Also leaving it as bats means you can't change the density of the stuffing.

dave

Would a layer of 20mm acoustic foam work - fixed to all internal surface areas instead of Dacron stuffing Dave ?
( Again, new to full range..1st build ). Thanks mate. Steve.

 

[planet10]

Acoustic foam is not all that effective.

Pluff up the dacron. Eaier if you start with poly fill as opposed to poly batting.

dave

 

[lorienblack]

For less than £20 you can buy carded, hollow fibre polyfill or toy stuffing. The improvement (SQ) over materials with less even consistency is considerable.

eBay item - 190899212947

Money well spent I promise.

 

[Stresss42]

Thanks Lorien, looking at that now...any idea what amount I should order ?

1 /2 / 5 KG for both Pencils ? Also where to put the stuffing and what
quantity. I'll PM you my system and room dims now to not draw this thread away from Pencil Pics ! Thanks again , appriciate your help. Steve.

More pics below of my build . . .

 

[lorienblack]

PC

From memory I put 500g in each of my pensil 10.3. Room 4m sqrd aprox and a well dampened room.

 

[Stresss42]

Stuffing pic from inside - room 3.5 x 7 mtrs.

Was just searching " pencil stuffing " on here, don't seem to be any
pictures / methods...I know it's room dependant so trial and error I guess
is the answer.

Getting a Dacron headache. ! Thanks again, Steve.

 

[lorienblack]

Leave a little room behind the driver, breathing space. Then spread as evenly as humanly possible throughout the rest of the box. IMO, too much and the sound becomes congested and boxy, too little and the bass becomes boomy and the soundstage suffers.

 

[Stresss42]

Thanks again for that - just ordered 2 KG : eBay item - 190899212947.

Hoping that'll be enough. Will use some of the existing Dacron glued at the base to support this new wadding.

" Too much stuffing...Sounds congested and boxy "...that sums up my current SQ. But very very impressed though, even at this early burn in stage.

All the best, Steve.

 

[Bigun]

Also leaving it as bats means you can't change the density of the stuffing.

maybe not, but it does compress and it's so much easier to remove it and reinstall it if required. Neither does it eventually fall out of any ports.

 

[planet10]

maybe not, but it does compress and it's so much easier to remove it and reinstall it if required. Neither does it eventually fall out of any ports.

Sure, if you want conveinience over performance.

dave

 

[Stresss42]

Hi all,

Just ripped out most of the wadding fitted at the back of the cabinets
held in place by the brace.

Night and day difference. Before ( with a very sensitive tinitus - suffering left ear ) the sound was very shrill - vocals were shouty, soudstage was lacking. All that remains are some 12" pieces of dacron fitted to the front and about 2" down from the bottom of the Alpairs.

Absolutely incredible difference, massive improvement.

Why's stuffing important if all the internal surfaces are very heavily bitumen damped with the best internal brace I could build ? Pictures below, very best regards, Steve.

Nb..The Alpairs will be 100Hz high passed so any boominess will hopefully be avoided ?

 

[Stresss42]

Pic of Bitumen over every internal surface . . .

Also all of the bitumen corner- joins / 90 degree angles were sealed and rounded with bitumen rubber paint.

Steve.

 

[planet10]

Why's stuffing important if all the internal surfaces are very heavily bitumen damped with the best internal brace I could build ?

All transmission lines have a fundemental 1/4 w/l resonance and a bunch of higher harmonic resonances. The fundemental improves bass extension, all the rest cause ripple in the LF response. The idea is to keep the 1st one, and eliminated all the rest. Driver offset can be used to mostly eliminate one of those, usually you try for the 1st one, a restricted terminus improves the low pass function of the line, but volume fill damping is a prime tool for reducing this ripple.

dave

 

[chrisb]

Bitumen padding is certainly one way to significantly reduce enclosure panel resonances, but that's not the only thing going on in any of the Qtr wave family (continuum) of designs.

Nice detail work on the internals, BTW

 

[planet10]

Bitumen padding is certainly one way to significantly reduce enclosure panel resonances

(Assumming bitumen padding -- you did also say paint)

Actually it can be a mixed bag. You are adding damping, which will suck up energy that can cause the panel to resonate, but you are also adding mass without stiffness which both lowers the (potential) resonance frequency and lowering the Q, which means there is more energy to excite it, and lower Q resonances are more audiable. Since it is solid you are also reducing enclosure volume, so changing the design parameters.

dave