La petite Onken

[Eldam]

Gotto ?

yes the half moon horn with a long neck and the CD above is a "pavillon replié" with a mouth of 1 quarter meter !

It seems more logical to have a cone driver for mid bass... (>80 hz) a strong electro magnet speaker could be good if No 'Voice of Theater" ?!. maybe a 2" CD >= (400-500 hz) is a good thing if you find the good match below (Onken à la TAD like Ibre ?) but a voice, a cello, going from a 15" to a fast horn.... you need a holy crossover to match the fastness, no (it seems impossible for me as a lot of people try to setup their 2 ways high efficienty speakers the half of their own life...)

 

[SebastienL]

Hi everyone,

Eldam, don't worry about the off topic because I'm also interested in advice regarding a 3 ways high efficiency (100 dB and more?) at first. It could have been my post before the petite Onken hit me, even if it's not totally in the high efficiency for me. It could be still good and I found an impedance graph of GPA 414-8B right here on DIYaudio:

http://www.diyaudio.com/forums/multi-way/202439-standing-waves-something-else.html

It looks like the GPA never goes lower than 7.5 ohms which seems very good. The parallel Beyma SM-122N woofers of my AMA 3x100 go down to 4 ohms. This is quite a good advantage for the GPA. Maybe both speakers will appear to have almost the same sensitivity. To see...

Regarding the horn, Francis told me that he will calculate their resonnant frequency when I'll receive them and send him measures of them. Thanks Francis! I guess that after that we will talk again about the cross-over point between the 414-8B and Emilar EA 175. I heard many good comments about cross-over frequencies between 800 and 1200 Hz with the 414-8B. Still have to see about its directivity.

Have a good day,

Sébastien

 

[Eldam]

What does GP Audio advise for XO slope & Fhz crossover - 3db ? second order (12 DB) for a good match (around 1.5 octave below and above the crossover) ?

 

[4mc2]

Pour moi , les chambres de compression c'est pas tellement pour l'efficacité mais plutôt pour la rapidité ( le temps de réponse ) parce que 100 db c'est déjà très bien .... avec un ampli de 50 watts ( la puissance de l'ampli n'est pas un facteur limitatif comme avec les SE ) .

Pour le mariage du CR et du driver basse / médium d'un deux voies , ce qui me plait le plus à l'oreille c'est avec un filtre de premier ordre à 1000 ou 1200 hz ..... évidemment ça prend un mid/bass qui monte haut et en finesse ( membrane légère ) mais , c'est un compromis en attendant le 3 voies car il manquera toujours de la nuance si je compare avec le Coral .

Sébastien , avec le 414-B tu vas mieux comprendre la différence du traitement du bas-médium ....... 29 gr versus 52 gr pour le Beyma , parce que lui pour supporter les 400 watts rms il doit avoir une membrane plus lourde et une bobine plus lourde aussi avec du fil de plus fort calibre toujours à cause de la puissance .......... Le pire , c'est que tu n'as pas besoin de toute cette puissance ! ..... avec un ampli de 20 watts ! .... la seule logique de Francis , c'était à cause qu'il voulait avoir la même efficacité que le PR 100 db ..... mais à quel prix ! ( musicalement , pour le bas médium ) ............ tandis qu'avec un seul 414-B ( d'une puissance beaucoup plus près de ton ampli ) et un ampli dédier on règle le problème d'une façon plus logique pour moi .

=================================

For me, the compression chambers is not so much efficiency, but rather to the speed ( response time ) because 100 db is already very well .... with an amp 50 watts ( power amp is not a limiting factor as with the SE) .

For the welding of CR and bass / midrange driver with a two-way , what pleases me most is the ear with a first-order filter 1000 or 1200 hz ..... it takes a mid / bass that goes up and smooth (light membrane ), but it is a compromie pending 3-way as it always less nuance if I compare with Coral.

Sebastian, with the B - 414 you'll understand the difference in the treatment of low - medium ....... 29 grams versus 52 grams for the Beyma , because he to support 400 watts rms it should have a more membrane heavy and also with heavier wire gauge in voice coil always stronger because of the power .......... the worst is that you do not need all that power ! ..... With a 20 watt amp ! The only logical .... Francis , it was because he wanted to have the same efficiency PR 100 db ..... but at what cost ! ( Musically for the lower midrange ) ............ whereas with a single 414- B ( power much closer to your amp ) and amp dedicate it solves the problem of a more logical way for me .

 

[SebastienL]

What does GP Audio advise for XO slope & Fhz crossover - 3db ? second order (12 DB) for a good match (around 1.5 octave below and above the crossover) ?

Bonsoir Eldam,

I asked them but got no answer. Actually, I found that GPA doesn't offer the best "future customer" service. In the last two weeks: two emails without any answer and an exchange via eBay with not much opening...

Sébastien

 

[SebastienL]

Pour moi , les chambres de compression c'est pas tellement pour l'efficacité mais plutôt pour la rapidité ( le temps de réponse ) parce que 100 db c'est déjà très bien .... avec un ampli de 50 watts ( la puissance de l'ampli n'est pas un facteur limitatif comme avec les SE ) .

Pour le mariage du CR et du driver basse / médium d'un deux voies , ce qui me plait le plus à l'oreille c'est avec un filtre de premier ordre à 1000 ou 1200 hz ..... évidemment ça prend un mid/bass qui monte haut et en finesse ( membrane légère ) mais , c'est un compromis en attendant le 3 voies car il manquera toujours de la nuance si je compare avec le Coral .

Sébastien , avec le 414-B tu vas mieux comprendre la différence du traitement du bas-médium ....... 29 gr versus 52 gr pour le Beyma , parce que lui pour supporter les 400 watts rms il doit avoir une membrane plus lourde et une bobine plus lourde aussi avec du fil de plus fort calibre toujours à cause de la puissance .......... Le pire , c'est que tu n'as pas besoin de toute cette puissance ! ..... avec un ampli de 20 watts ! .... la seule logique de Francis , c'était à cause qu'il voulait avoir la même efficacité que le PR 100 db ..... mais à quel prix ! ( musicalement , pour le bas médium ) ............ tandis qu'avec un seul 414-B ( d'une puissance beaucoup plus près de ton ampli ) et un ampli dédier on règle le problème d'une façon plus logique pour moi

Salut Michel,

Pretty interesting what you are saying. I learn from it the difference in the mass of both woofers (Beyma and GPA). I guess that's why there is so many good comments on the 414-8B.

Regardind the "bas-médium" (low mid?), Francis talks in its books about the importance of it.

Bonne soirée,

Sébastien

 

[Eldam]

yes: the dynamic, the transcient... less distorsion at same midle volume DB than low efficienty. And more difference db level with dynamic between two notes !

We live here with very low to low efficienty (85 Db/ 6 ohms to 92 db/ 4 ohms with a 89 db/8 ohms as third system... this last always off because lake of space !)

My understanding is F. Ibre love live music and is looked for with 10 000 000 dollars on his head by him neigbours because he listen to live level classic music (for having the DB level contrast with dynamic)

4mC2 maybe would mean than a first slope is better for dynamic and matching two different drivers because slope is slow (6 dB & phase accurate) and mostly the two voices need more than 2 octaves between each side of the crossover to work together (my understanding on his answer): so walking to the marmelade speed to the light speed transition is more easy (remember Star Wars when the Falcon is hunted by the big Emperor ships ! when it accelerates : by by the medium !); Of course it'e a simplification, I'm not a designer myself and if you take some others parameters like polar response, room (good is the F Ibre book just for that !) and age of the capitain for the tweeters and the dog (who hear the tweeter)... it's far more uneasy ! So active with phase correction is your friend and a big toy for our hobby !

@ Sebastien : I think this is a brand for enthusiasts who know already the Altec world. Here we had famous brands but with the lake of dynamics & investements for new products & marketing talent they just survive despite some very good productS/ Audax (production on demand), Siare (bought by Audax), Supravox (maid on demand), Fertin (But EMS Speakers now with good focused production) :cabasse doesn't sell to diyer anymore, almost Focal (JM lab)... some others brands found niches : PHL Audio (ancient tech director of Audax) for high efficienty (pro loudspeakers : if you want a good mid PHL1020 : 10 g mms !), Davis : (works for brand and has its self speakers)... Rare are the brands who have accurate measurement : most of the time the well known of North Europe and above brands ! Great sperakers of course in GB in low efficienty... For th ehigh efficienty you know where are the goods brands (Italia, Spain, USA, GB, ...).

 

[SebastienL]

Bonjour Eldam, hi everyone,

I'm not sure I entirely understand the story with the money "...F. Ibre love live music and is looked for with 10 000 000 dollars on his head by him neigbours...". Anyway, on my side I realized that an high efficiency system add many good things to the sound at low volume. Sometimes, when I'm alone, I listen to music at normal live level but at night, it goes lower.

I agree with you regarding Audax. It was a nice discover for me last year with the PR170ZO.

À +

Sébastien

 

[Eldam]

It was a a joke : he is wanted with a big money surprime from him neighbours.. because he listen to classic music at live db level.

Very rare than the PR you have, i can not understand it is not in current production anymore ! maybe hard to use because it high Fs... hé it could be match between the Onken and a TPL150, the day you buy a tweeter above the Emilar...try the PR without the Emilar and try the TPL150 with its short horn at around 1500 hz !
Or ask to Ibre how to use the PR in a vented box to lower the XO frequency ! He knows this driver very well !

 

[DrBoar]

I think he means that the guy has a price on his head, to the tune of 10 mill...

Regarding 6 dB filter, if the drivers are flat with at least a 4 octave overlap, and you adjust the filters for impedance variation near or in those 4 octaves the high range driver still has to be able to be able to take the power and convert that to sound out two octaves below the nominal crossover frequency.

 

[Eldam]

Yes that's what i wanted to say.

And I'm not sure than the Emilar is flat to 300 hz in the hope to use a first order slope at 1200 hz for the crossover. It seems more easier for the Altec above this point.. at least for the first octave above the XO (+1 octave=2400 hz) assuming peaks or distorsion of the Altec in the second octave would be flooded enough... But it's just theory.

IMHO, many testimonies said Bass XO without active EQ for rapid test is a difficult and expensive task. I think the best for Sebastien is to follow the advice of F. Ibre who take a lot of time to share for the others and will calculate the Fs and T. factor of the Emilar horn... Step by step, purchase by purchase, the speaker will be improve : another driver, class A amp for the bass or class D plate amp with XO EQ... and so on.

 

[4mc2]

Oui bien sur que 2 octaves de chaque coté c'est mieux mais une seule pour le CD c'est mieux que rien .

Sébastien , j'ai regarder sur le site de GPA , j'ai l'impression qu'il utilise la même membrane pour le B et le C , c'est seulement l'aimant qui diffère ...... à moins d'avoir l'original , tu risque fort de ne pas avoir une membrane légère .

Mais il y a un moyen indirect d'en avoir une idée ......... une membrane légère monte haut en fréquence ............ on peut différencier entre un HP grave et un grave-médium en regardant la courbe des fréquences .


=========================================

Yes of course that 2 octaves on each side is better but only for the CD is better than nothing.

Sebastian, I look on the website of GPA, I feel it uses the same membrane for B and C, only the magnet differs ...... unless have the original, you may well not be a slight membrane.

But there is an indirect way to get an idea ......... membrane slight rises high frequency ............ we can differentiate between serious and HP bass-midrange watching the frequency curve.

 

[GM]

Actually, I found that GPA doesn't offer the best "future customer" service.

Sadly, this is true, they generally only respond to phone calls due to lack of personnel and even then only WRT shop orders AFAIK.

GM

 

[GM]

And I'm not sure than the Emilar is flat to 300 hz in the hope to use a first order slope at 1200 hz for the crossover. It seems more easier for the Altec above this point.. at least for the first octave above the XO (+1 octave=2400 hz) assuming peaks or distorsion of the Altec in the second octave would be flooded enough... But it's just theory.

I seriously doubt it unless it’s larger [and longer if for a 1” driver] than a W.E./Altec 300 Hz multi-cell or sectoral horn.

IME, for 1st order slope with Altec 1" drivers it takes a ~2400 Hz XO point with a 500 Hz 511 horn, basically turning the horn into a rising on axis wave guide [WG] with a much flatter overall response, which for many folks is a good thing since it keeps the horn from 'honking' and reduces the number of passive components in the signal path.

WRT using a larger driver to go lower, I couldn’t tolerate the 288B’s very narrow ‘sweet spot’ and somewhat lacking extreme HF in my youth, but didn’t want to lose the ‘full’/’robust’ lower mids of the 805 multi-cells, so swapped the pair out for four 511/802D horns, ‘stacking’ them two/channel and rolling off one of the drivers in each pair to have my ‘cake and eat it too’, gaining greater efficiency, slightly greater power handling due to a greater total driver piston and horn mouth area and a ‘tighter’/flatter polar response [especially in the vertical] with the better HF response of the smaller driver.

That was in 1970 though, today a single multi-cell/1.4” driver horn generally commands a [much] higher price than even four new GPA 511/802 horns, so for other than the ‘look’ of a multi-cell, I see no reason to waste the $$$ on them in a HIFI/HT app.

Ultimately though, I replaced them with very large DIY conical 90x40 WGs [visualize a little larger rectangular DSL SH50 Synergy concept horn with only a 1” driver] to get a much lower distortion, flatter polar response all the way out to 20 kHz at the expense of a ~10 dB lower system efficiency, which was still ~103 dB in room, so plenty high enough for the vast majority of HIFI/HT apps.

GM

 

[4mc2]

Very special this " DSL SH50 Synergy concept "

http://www.diyaudio.com/forums/mult...idrange-cone-bandpass-mid-unity-horn-157.html

 

[SebastienL]

Hi there,

Just to tell you that Bill from GPA told me that the GPA 414-8B has a "...minimum impedance spec of 7.1 ohms measured from 100Hz to 250 Hz free air."

It seems to concord with the measure I saw once from someone on the web.

Have a good day,

Sébastien

 

[SebastienL]

Greets!

Originally, I suggested leaving it at 155 L because the drivers you buy may have different specs and way more often than not this dictates a larger cab tuned lower to maintain a similar/same overall response slope cab alignment.

For instance, another original 414-8B’s specs would need to be ~221.5 L/~35 Hz Fb using Hiraga’s math, so between Hiraga’s driver and this other one it’s obvious that like most [all?] manufacturers, Altec played ‘fast and loose’ over time WRT what it built to keep up with the rapidly changing ‘world’ of electronics that had amp damping factors [DF] zooming up [eventually spiraling down output impedance into tiny fractions of an ohm], which required the driver+cab alignment to become the primary source of damping.

Don’t know what you mean by 1 ohm being worse than 2 ohm since the higher the resistance the more under-damped [‘loose’/’boomy’] the cab alignment becomes and why doing a proper Onken seems the way to go if an Onken is what you want, i.e. there’s nothing special about Hiraga’s alignment and arguably a poor choice overall in many [most?] apps since it doesn’t take the driver’s effective damping [Qts] into account, not to mention that to get the max bass efficiency with a high output impedance requires the cab be accurately tuned to the driver’s Fs.

Anyway, IF GPA builds yours to spec, then using an Onken calculator and adding 2 ohms of amp resistance and a ½ ohm of wiring resistance ideally requires a 180.8 L/34 Hz Fb.

To the first approximation then, ‘critically’ damping the 155 L’s vents in room should do just fine. Ideally you would do this with an impulse response, but normally just finding the point by ear where it sounds ‘tight’ and any more damping just obviously is rolling off the bass is sufficient, just be sure that the HF is disconnected during the tests.

If I use the older 414-8B’s specs though, it zooms up to 394.41 L/23.15 Hz!

In 155 L then, it will need to be either heavily stuffed [~aperiodically damped] or sealed.

GM

Hi GM, hi everyone,

I was reading again this week on the "right" charge for the driver used. On Mélaudia forum, someone talked much about it for the Onken 360L. In our case with the petite Onken, we are talking about Great Plain Audio 414-8B. As I understand from a past GM sentence, the Qts will change according to the damping factor of the amplifier combined with driver itself. But I was wondering if a software, like ARTA for example, could be set-uped to include this. Could it?

I was also wondering how do we calculated this. I know that in this thread, GM, you had refer about many possibile volume for a petite Onken using a GPA 414-8B. First, the result was 106.91L/40.14 Hz alignment. Then, regarding the amplifier damping factor of "...2 ohms plus ½ ohm of wiring resistance ideally requires a 180.8 L/34 Hz Fb".

Then, from "...original 414-8B’s specs would need to be ~221.5 L/~35 Hz or 394.41 L/23.15 Hz..." That even transcend regular Onken volume design!

Anyway, as I consider one day to biamplified, the "original" volume from M. Koïzumi still seems the way to keep.

I'm just about to receive my compression driver and horn. I'm excited.

Have a good week-end,

Sébastien

 

[GM]

Greets!

I have no knowledge of Arta, though you can add series resistance in WinISD Pro, ditto Hornresp, MJK’s MathCad software, LispCad and no doubt AkAbak and other TL/horn programs. Pretty sure Unibox and similar programs have the option.

Regardless, you can increase the driver’s [Re] and calculate the new Qes, Qts to input: mh-audio.nl - Home

The math:

Qes' = [(Rg + Re) / Re] * Qes

Where:

Re is the DC resistance of the driver
Rg is the additional impedance
Qes is the Electrical Q of the driver

Qts' the new total Q of the driver can then be found by:

Qts' = (Qes' * Qms) / (Qes' + Qms)

Where:

Qms is the Mechanical Q of the driver.

New, lower effective efficiency:

n0’ = ~ [9.6352*10^-10*Fs^3*Vas]/Qes’

SPLeff’ = ~ 112.018+10*log10[n0’]

GM

 

[SebastienL]

Hi there,

I'll be a bit off topic here, but it seems that we, as DIYers, could have a really precise speakers for our room and system (see amplifier damping factor). As I understand, companies could'nt do this so precisely. Then, how do they chose to make most of the buyers happy.

GM, thanks for your answer regarding calculations. It doesn't matter regarding it is or not for ARTA. I was just wondering how do such program integrate those calculations.

Have a good day,

Sébastien

 

[SebastienL]

Hi there,

I've just had Bill from Great Plains Audio on the phone this afternoon. I was just about to make a "mistake" and buy a 414-8C from them on eBay. We have to be carefull because the title also contain 414-8B number, pretty strange...

Anyway, Bill told me that 414-8B is the Alnico magnet version and the 414-8C is the ceramic version. From his statement, himself even doesn't heard a difference between those two and all the measures of both of them seems pretty the same. There is a price difference of about $70 from one to another (Alnico more expensive).

On my side, I think that I'll go with the Alnico. Maybe because it "could" be better and I don't want to always wonder what the Alnico might have been sounding, etc... You see.

This said, Bill is supposed to send me the technical detail of the 414-8C GPA version. They are not on their website. I'll report later.

Finally, I was a bit surprised that Bill doesn't know the petite Onken. This speaker seems to have a great place in audio history, also in the Onken large family.

A good day,

Sébastien