[zmyrna]

My lampizator style OB project is shaping up slowly.
At the heart of the system will be some vintage alnico wide rangers and paper cone tweeters.
I already have a pair of new old stock Isophon p203c (4 ohms).
Also on their way are a set of Seas 21TV-GV and 9TV-LG (both 4 ohm versions).
Pls see this for the Seas drivers: http://www.troelsgravesen.dk/blackcones.htm
Once all drivers are here, I will compare Seas vs Isophon mids on a test baffle using Lampizator's first order crossover (3,3 uF for tweeter, 100uF/0,39mH for mid). I might try to find an 4" open back Isophon tweeter for an all Isophon mid+tweet set.
I think both Isophon and Seas mids are about 96db efficient. I hope the cone tweeters can keep up with them. Once it is all over I might also try to dial in a pair of cheap Monacor ribbons as supertweeters.
Now the tricky bit and my questions:
For the helper bass, I am hoping to clone Lampizator's P24 or P25.
http://lampizator.eu/SPEAKERS/PROJECTS/P24/P24_monster_speakers_raal_altec_lansing.html
http://lampizator.eu/SPEAKERS/PROJECTS/P25/Greencone_Saba_Maximus_Lampizator.html
If I go P24, I am thinking of using cheap Chinese proaudio SoundLab drivers:
http://www.jpgelectronics.com/search.asp?searchbox6=Bass%20Speakers&templateid=29
The 4 way system will be: 1. cone tweeter, 2. wide ranger, 3. two 8" Soundlab woofers, and 4. 15" Soundlab woofer.
If I go three way P25 route, I am thinking of trying two Isophon p203s woofers per side as helper bass (instead of two 10" greencones).
I haven't seen anybody using these 8" drivers for bass on OB. Specifications seem to be okay though: 93db, mms 16gr, qts 0.42, fs 30hz.
p203s is very similar to p203c except for rubber surround and very high excursion. I am worried how these vintage woofers would sound as helper bass on open baffle and how well they would blend with the wide ranger. Any comments?
And please comment on my driver selection in general and which way to go: P24 or P25.
I also have a specific question on impedance matching: Lampizator seems to be using 8ohm helper bass together with 4ohm mid rangers in many of his projects. Is this usually okay or should I try to keep everything at 4 ohm? This can easily be achieved if I do my P24 clone. I can use two Soundlab 8" 8ohms parallel and a single 4ohm 15".
P25 clone is more tricky. Most p203s available are 4ohm. I can use two of these wired parallel for a total of 8ohm (would this be okay?). Or try to find 8ohm versions to give 4ohm wired in series. Please advise.

[zmyrna]

My ooops moment. I think series/parallel needs to be switched in the last paragraph.

[Æ]

Paper cone tweeters? I have never, and I mean never, ever heard a higher fidelity paper cone tweeter. Also cone tweeters are larger in diameter then dome tweeters, and because of that they start to beam at a lower frequency than dome tweeters. Here is a good example of a paper cone, found inside a $2.99 piezo tweeter.

[zmyrna]

Seas alnicos are here. The woofer turned out to be 8ohm and the tweeter 16ohm.
The previous owner was using them wired parallel with just a 2.2uF on the tweeter.
I hooked them same way. I was worried that w and t would have different efficiency,
but they seem to work fine together. A lower two way 1st order crossover will probably make an improvement.
First listening impressions:
Tweeters definitely improve the sound and add stage and airiness. They blend very well.
I also hooked an Isophon on its own to the other channel.
Surprisingly they seem to be very similar efficiency (Seas vs Isophon).
Remember that Isophon is NOS and not broken in.
Isophon sounds more colored: bit resonant like a horn. It is not a bad thing though: makes it more engaging and bigger sound stage too.
Seas is more neutral probably because of its shallower profile.
Isophon also seems to have a bigger rising response: brighter and (fakely) more detailed than Seas.
I am thinking of trying Seas and Isophon woofers with a Monacor Ribbon,
compare it to the 2 way cone tweeter set up,
and potentially try a 3 way woofer+cone tweeter+ribbon option.
Once mid-high is resolved, I will also add helping bass.
The reason of trying the paper cone tweeter is because it is probably the best option in terms of blending with the cone midrange.

[zmyrna]

more pictures

[scorpion]

Zmyrna, those Isophones look really good. Hope they sound as good as they look. 
Lampizator, I think, has been quite inspirational to a lot of people, for good reasons.
Now I would dare to venture the Neo3W as a very good alternative to augmenting your midrangers.
It can be crossed actively around 2 kHz and passively 12 dB/oct around 2.5 - 3 kHz without problems.
I have experience with the Monacor 'ribbon' magnetostatics and I am certain they fall short of the Neos.

/Erling

[zmyrna]

Thanks for the replies.
The NOS Isophons are ubercool indeed, Erling.
They came in original sealed boxes 
I hope they will sound much better when low passed just before their response starts to rise.
Neo3 was my top choice for a long time, but then I read a lot saying it does not blend well with widerangers.
I was thinking of using the original Neo3 (not the PDRW), because of its higher eff and perhaps better match for wideranger's dispersion.
For experimenting, I thought I should use the cheap Monacor ribbon. I could try it as a tweet with the wideranger (2nd order high passed around 5k), or as a supertweet on top of a 4" papercone.
If none of those worked well, my next choice would be a cheap horn like BMS 4524.
I do not want to go active because I have a strong attachment to my amplifier: a digital Tact unit.
It works like a power DAC, and adding channels would probably be impractical.

[zmyrna]

One other reason for liking the paper cone tweeter is that it is dipole.
A 3-4" cone starts to roll off gently after 10k: It could well be the best option to cover 5k-10k on an open baffle. It would be cool to have an omni tweeter dialing in after 10k. A conventional ribbon otherwise.
Or a DIY version of this:
http://www.mark-daniel.com/Pro_En.asp?ProID=8

[scorpion]

Hi Zmyrna,

The argument about Neo3W I don't buy at all. But it is perhaps a question of use of the midranger also, if HPed or not.
You have to try. But regarding the Neo3W (not PDR) it's by a far marging the best dipole tweeter I have used, back removed.
I think you should regard a normal 3-way for the Isophones as the main alternative.

/Erling

[zmyrna]

I think i will end up ordering a pair of Neo3.
Erling, where can I get them in Europe? B&G have a direct order phone line? Has anyone ordered from them?
I plan to use Lampizator P24 crossover as a starting point.
He uses a 2nd order filter on Raal around 5k.
And an earlier (3.5k) point 1st order for Isophon (because of the rising response).
I can also try my Heil tweeters on the same set up.
Standard neo3 will probably blend better crossed that high.
Can I reattach the back cover of neo3 if I like them that way more?

[scorpion]

I bought here: http://www.audiophonics.fr/tweeter-ruban-bohlender-graebener-neo3w-p-3687.html .

I think you could reattach Neo3's backcups with some glue, that's how they are attached in the first place.

/Erling

[richardcooper2k]

Hi. I have built something like lampizator speaker project 17 but with a different baffle arrangement.
I like it a lot.

The Saba midrange drivers in my speakers are 95dB sensitive. If your isophons are similar you may need to pad back the midrange with the less sensitive Neo3s.
I am using Saba tweeters which seem to be even more sensitive than the midrangers.
The combination sounds very detailed and sweet to my ears.
The high sensitivity is great for low powered SET amps like mine
I did think about trying the Neo3's.
I have had difficulty finding bass drivers sensitive enough to match the sabas
 

Erling, have you compared the Neo's with any vintage tweeters like the sabas ?

[scorpion]

No, I have not I'm afraid.

/Erling

[zmyrna]

On some webpages, neo3 is reported to be 95-96db.
Isophons are indeed slightly less eff than Sabas.
And the Seas alnicos I have are a further bit less efficient than the Isophons.
So I can make sth work with the neo3.
I lost an ebay auction for a pair of Seas tweeters (same as mine but 8ohm version) last weekend 
I will keep looking for the perfectly matched Seas drivers.
Erling, thanks for the link. Those are not very cheap. I shall give a call to B&G and see if they sell direct.

[zmyrna]

Since my last post, I have been buying more vintage Seas gear.
For 20 GBP, I purchased a pair of Sony S-2030, from late 1970s.
See this website for pictures of boxes and drivers:
http://www.audiovintage.fr/leforum/viewtopic.php?f=20&t=9071
Each box have a Seas 21F-GWS, 10F-LGS and 5TV-HFS. All 8ohms.
My initial plan is to use this speaker as a mid-treble box sitting on a separate bass box.
I am saying box, because they will look like boxes but in fact be open baffled.
First I will cut open all sides of the Sony speaker except for base and front,
leaving the 3D skeleton intact. And then I will wrap the whole thing in speaker cloth making it look like a box.
The bass boxes will be boxes but with open backs.
I will place sorbothane feet between bass box and mid-treble box for isolation.
I might replace the ferrite 21F-GWS with the alnico 21TV I have.
I would love to use the 9TV instead of the 10F, but the 9TVs I have are 16ohms.
Can this be done by changing the crossover components?

Now to the more difficult bass box:
I am now the proud owner of a total of 8 Seas 21TV-EW s.
From behind, these look exactly same as the other 21TV I have.
The difference in the front is that EWs have rubber surround and thus a much higher excursion.
The Fs is said to be 30Hz and  sensitivity at around 89db.
The mids on these things are just lovely.
The problematic bit is that EWs I have are 15ohms each.
If I wire 4 in parallel it will give me just under 4ohms on each side.
If I go 2 parallel 2 series, it will be 15ohms.
Are these resistance points workable in the crossover.
Should I try to find 4 more EWs to have 3/3 parallel/series on each side? (6 woofers on each bass box)
That would make 10ohms per side, a better load?