[pol_bct]

Hi Pol , Zygadr..
Can you explain me please why one way is better than the other? Is confusing having two opposite opinions 

Hello
I have zero explaination,
this is stricly the same from an electrical pt of vue
the total surface of radiation is the same = zero gain
the total impedance is the same = same power applied
It could be very different if you put all tranducers in //
versus all transducers in serie,
but we are not talking this option, are we ?

by experience, one sounds muffled an the other sounds "open"
I did it more than one time, because I build louspeakers for friends
with 2 stacks of 25,  Fostex_FE83 wired 5x5 
but stacks of 25 transducers is a little bit more than 2x2

POL

[Æ]

Hi Pol , Zygadr..
Can you explain me please why one way is better than the other? Is confusing having two opposite opinions 

When you parallel two identical woofers you get +6dB sensitivity for the same amplifier voltage. But I kind of doubt it's the same with exciters, when they are attached to the same diaphragm. I'm kind of skeptical of Zygadr's explanation unless it was confirmed via a calibrated microphone.

[zygadr]

Grab a piece of cardboard, EPS or similar. Place one exciter on the panel and listen. Then place a second exciter, connected paralell to the first and listen again.

[pol_bct]

Grab a piece of cardboard, EPS or similar. Place one exciter on the panel and listen. Then place a second exciter, connected paralell to the first and listen again.

by doing this we will probably get above 3 dB, but not 6dB
the surface of radiation has not doubled, only the excitation power
and the question was about the electrical and acoustical
equivalence of serie+// versus //+serie, at same impedance.

POL

[Æ]

by doing this we will probably get above 3 dB, but not 6dB the surface of radiation has not doubled, only the excitation power

Yes, that is kind of what I am thinking too.

[zygadr]

Yes, that is kind of what I am thinking too.

Podium Loudspeakers use 4 exciters in their top model. The exciters used are the bolt to a frame ''high shove variety''. They are documented from specifications I have here at home which were provided to me by NXT in England as 79.6 db efficient.

When reviewed very thoroughly,(look on their website for reviews) including response curves, impedance levels etc., the Podiums measured 89db+(Podium claim 92db) sensitive (with 4 exciters, remember)

How do you explain an increase of 10db as opposed to your ''thinking'' of :  3db?????.

[pol_bct]

.....
provided to me by NXT in England as 79.6 db efficient.
.......
 the Podiums measured 89db+(Podium claim 92db) sensitive (with 4 exciters, remember)
.................
How do you explain an increase of 10db as opposed to your ''thinking'' of :  3db?????.

quite easily, probably different surfaces of radiation, different panels materials, then different young's modulus, and maybe different distances,.... you know publicity, the modern lie

as I remember, the talk was about about 4 transducers, not 2 transducers
so slightly above 3dB, lets say 4/5 dB, plus doubling to 4 motors lead us to to 4/5+3 = 7/8dB

POL

[zygadr]

Yes, agreed. That's most likely to be the real gain in db.

[tino84]

It seems that someone shipped something today from Germany..(finally)

[zygadr]

HOORAY!!!!!

[tino84]

[tino84]

yeah,monacor sounds good 

[Abelma]

[

[tino84]

I can compare with NXT

http://www.parts-express.com/pe/showdetl.cfm?Partnumber=309-148

it's soon,but it seems that Monacor have a richer sound,but a bit "closed".A little more bass (,but nothing compare to a 30cm woofer  ). still don't know if will change a bit playing.

Nxt are brighter.

A slightly difference between Ar-30 and Ar-50,not so evident at the moment (due to size,less bass and a little brighet for ar-30).

Also for NXt,so monacors are susceptible to clipping.(would ask to monacor if it's a technology limit or depending on material used)
I'm not also sure if , as for NXT, best material = thin,solid and light. I have to check it better.
Don't think if it would be the best tactile transducer,sure there are some improvements.But let them playing a little more.

I use Ikea Vika Amon

http://www.ikea.com/it/it/catalog/products/90071168/

and 2 wharfedale woofers 30cm
 

[panomaniac]

Is the Vika Amon table top hollow core?  Built like a hollow door?

[j gale]

I bought a Vika Amon to try. It's heavy but doesn't sound bad. It is like a hollow door. The frame is particle board 1" wide on the sides and about 6" wide on the ends where legs are attached. I cut 6" off each end and 1" off each side leaving just the surfaces and the cardboard core. Much lighter now and the sandwich stays together just fine. Now it sounds very good. The core material is thin and rigid. I find it an improvement over the 3 mil mahogany ply I tried which was quite good too. I would dearly like to get a hold of a honeycomb paper panel about 1/2" thick and experiment with treating it with shellac etc. My wife is very impressed with the Vika Amon now that it is cut down. The exposed edge looks OK too.

[tino84]

I'm happy you got good results as me 

I think the combination between (simil) wood and paper (and its solidity) gives these warm and rich sound even if vika amon,following numbers, would not compare to lighter materials.
I still haven't time to cut the chipboard part,but I'm happy you got also better result,it's a thing that I must do 

My opinon,vika amon is the best material I tried (and no,ikea won't pay me every time I say it  )

[tino84]

has anyone used visaton bs 76?

http://www.vergelijk.nl/luidspreker/visaton/bs_76/specs.rhtml

and any of those "bass shaker"?

http://www.ebay.de/itm/2-Stuck-Bodyshaker-Body-Bass-Shaker-NEU-100W-Neu-Unbenutzt-/270862045724?pt=DE_Lautsprecher_Martin&hash=item3f10a2d21c

http://www.ebay.de/itm/2x-PROFI-BASSSHAKER-BASS-BODY-SHAKER-BUTT-KICKER-100W-ALU-DRUCKGUs-GEHAUSE-/120784336020?pt=Lautsprecher_Selbstbau&hash=item1c1f4eb494

http://www.ebay.de/itm/Sinuslive-BassPump-BODY-SHAKER-Bass-Simulator-4-Ohm-NEU-/200582008317?pt=Lautsprecher_Selbstbau&hash=item2eb39e8dfd

are those useful to obtain audible bass (around 200hz)

[zygadr]

I bought a Vika Amon to try. It's heavy but doesn't sound bad. It is like a hollow door. The frame is particle board 1" wide on the sides and about 6" wide on the ends where legs are attached. I cut 6" off each end and 1" off each side leaving just the surfaces and the cardboard core. Much lighter now and the sandwich stays together just fine. Now it sounds very good. The core material is thin and rigid. I find it an improvement over the 3 mil mahogany ply I tried which was quite good too. I would dearly like to get a hold of a honeycomb paper panel about 1/2" thick and experiment with treating it with shellac etc. My wife is very impressed with the Vika Amon now that it is cut down. The exposed edge looks OK too.

How about some pics for us to see your ''vika amon modified panels'' j gale?

[jonners]

Looking for Nomex? Choose some wood, make your own sandwich....   http://www.madinter.com/b2c/index.php?page=pp_productos.php&tbusq=1&ref=SF-NOM&md=1