My 'Volks-OB' Mission Accomplished

Mr Content · « **Reply #40 on:** 8 Aug 2008, 11:58 am »

Hi Erling, great work. Hey what are your thoughts about the cone presser on the rope mounting. I am a fan of magnet mount, and I will try this rope system, but I would use a more rear tiedown method, as opposed to a side tie down method. Do you feel this would make a difference.....especially on the bass driver???? I am thinking about the rope,.....after a weeks, months... the rope may stretch...maybe, and need to be tightened? Not in any criticising this system, just thinking it out a bit more aa

Mr C

scorpion · « **Reply #41 on:** 8 Aug 2008, 12:09 pm »

Hi Nigel,

Feel free to experiment as far as you like. No border imposed by me.
Myself I think I will be going towards 'Magnet-Mount' but with a little bit different approach.

/Erling

Mr Content · « **Reply #42 on:** 8 Aug 2008, 12:34 pm »

Thanks Erling, nice to chat anyway my friend, what do they say.......more than one way to skin a cat

Mr C

Rudolf · « **Reply #43 on:** 8 Aug 2008, 12:38 pm »

Hi Erling,
thanks for trying out this reverse-mount so rapidly

So it seems at least worth a try. How it works out could be quite dependent on the individual room situation.
I had already forgotten that your special driver mounting system needs an extra effort to get into "reverse gear".

panomaniac · « **Reply #44 on:** 8 Aug 2008, 06:33 pm »

Cool flip-flop! And thanks for the Swedish quotes.*
Now you have a rear facing tweeter. =) They can be quite nice, tho should be subtle.
Maybe if you run it like this for awhile, then go back to both front facing, you may notice more of a difference.

Yes, those Obbligato caps are nice. I even used them as T-Amp input cops - very nice. But I agree that the Trends just does not have enough power to do OB bass. But it makes a great midrange driver. And the 4 ohm solution your are using is the best.

*About 20 years ago I was trying to learn Swedish, and making some progress. But in Göteborg they told me: "Learning Swedish? That's silly. Here - everyone speaks English. Everywhere else - no one speaks Swedish. Why bother?"

scorpion · « **Reply #45 on:** 9 Aug 2008, 09:31 pm »

Pano,

Yes Swedes like Danes, Nowegians, and Dutch people really master English, and we should after 9 years of it in School. Also we never had any dubbing in Film or TV, only translation text below the picture. So all know the English intonation.

However my Swedish quote was also to add some reality to my claims of the Volks-OB as a really good speaker. If my German had been a little better I should have published the design also in a German Forum because most of the parts really are German.

/Erling

bbaker6212 · « **Reply #46 on:** 7 Sep 2008, 09:38 am »

From what I can see both of these drivers, the Monocor SP-130X, and the A&D R-1524, are all but impossible to purchase in the USA. Due to shipping costs purchasing from lautsprechershop.de is around $100 for a pair of SP-130's, which more than doubles their price and begs the use of some other locally sourced driver. If I'm wrong, would someone enlighten me? I'm sure an adequate subsitute could be found for the A&D bass driver, but not for the Monocor.

-Brad-

Rudolf · « **Reply #47 on:** 7 Sep 2008, 09:02 pm »

Quote from: bbaker6212 on 7 Sep 2008, 09:38 am

I'm sure an adequate subsitute could be found for the A&D bass driver, but not for the Monocor.

-Brad-

AFAIK the SP-130X is a product of the former czech TESLA factory, now www.tvm-valmez.cz
Nearest relative from the official sales program seems to be the ARO 468K www.tvm-valmez.cz/index.php?id=110&catit=180&catg=27. The design might well stem from the 1950-60th. So you better look for some vintage drivers to get comparable specs.

Rudolf

scorpion · « **Reply #48 on:** 8 Sep 2008, 04:08 pm »

No doubt Rudolf is right that SP130X/8 is of Czech origin and that the ARO468K at least is a look-a-like. There are however some differences, the most important one would be that the voice coil former is made from paper in the Monacor unit like in the Fostex FE-series. Also frequency response seems more smooth for SP130. My design was a bit inspired by: http://www.mother-of-tone.com/index.htm . Monacor has had the unit for not longer than three years. I have altogether bought 8 units from Germany. The first pair already in 2006. In fact SP130X/8 stand comparison with the Visaton B200 when used from about 250 Hz and upwards, also look how I have damped the unit with felt and bitumen, see above.

A pair of SP130X/8 will weight 1 lb and a DHL Päckchen (little parcel) under 2 kg (4 lbs) will cost 12.90 Euro (20$) from Germany to the USA, so contact Mr Vollstädt on Spectrum Audio: http://www.spectrumaudio.de/ for a more realistic freight quotation.

As for an alternative altogether I would recommend Martin J Kings's: http://www.quarter-wave.com/OBs/OB_Design.pdf.
For the 'Volks-OB' Eminence Alpha15A is an exellent alternative. I would then use 2 SP130X/8s per baffle as in the MKII design and keep the crossover filter unchanged.

I will conclude with a distortion measurement for the 'Volks-OB' MKII at 90 dB SPL:

/Erling

scorpion · « **Reply #49 on:** 9 Sep 2008, 12:39 pm »

As a consequence of Brad's question I contacted Wolfgang Vollstädt at Spectrum Audio, Bremen, Germany, http://www.spectrumaudio.de/ , for a quotation
regarding sending SP-130X/8s to USA. May be his answer is of some general interest so I will publish some details here (even if it may be a bit aginst rules):

'
Pro forma: Rechnung - Invoice - Facture - Fattura 8253-4
shipping-, invoice-address

Erling Petersson
USA

2* Monacor SP-130X = 26.90 EUR ( in stock)
1* shipping ground ( as registered letter) = 10.05 EUR
1* 3,5% PAYPAL charge = 1.29 EUR
-----------------
total value excl.VAT = 38.24 ( 36.95 ) EUR

Only advance payment
with card to my PAYPAL account : spectrumaudio@t-online.de
go to www.paypal.com and read instruktions
I must add 3,5 % to total value for my PAYPAL charge '

So there should be possibilities of arranging favorable ground shipping to almost any place in the world, I think !

/Erling

jacozz · « **Reply #50 on:** 14 Mar 2012, 07:28 pm »

Hello Erling!
I'm also using the AD 1524 woofer, but with the tangband 1772 in OB with great results. The woofers are active, powered with Hypex plate amps crossed around 140 hz or so... The Tangbands are fullrange without any filters or XO.

My Question to you: How do you think the AD 1524 compares to your AE IB?
I feel the AD1524 is really good, but choke on really high db:s due to lack of Xmax (6mm).
My room have a node-peak around 34 HZ, and for that reason I don't feel the need for the woofer to reach lower than... 40 hz on it's own.

I'm eyeballing the new AE SPB-15 (the IB replacement). But it's pricey and I'm not sure if it's worth the price, compared to the 1524.

What do you think?

/Jacozz

Vigoon · « **Reply #51 on:** 20 Apr 2012, 06:17 pm »

I had started to build one set of Volks-OB but here came some very bad news: the Monacor SP-130X/8 are not manufactured anymore and stock have run out...I had already finished all the wood work (made of bamboo) when I got those bad news...

The one OB I finished is running wonderfully...

Do anybody has one 2x Monacor SP-130X/8 or has a suggestion for a replacement??? I was thinking about a Visaton B200 (but they are 6 Ohms) or eventually the Beyma 8AG/N

Thank you in advance for your help...

scorpion · « **Reply #52 on:** 21 Apr 2012, 07:23 am »

I am away in Australia at the moment but have thought of updating the Volks-OB to a new version because it really was a good design. Maybe http://www.spectrumaudio.de/ still have the Monacor 130/X8, if so they are worth getting, Building myself I would go with the first version with one A&D R1524 and one Monacor 130 and the corresponding crossover.

Regarding jacozz question about the A&D R1524 I am happy to say that this speaker compares extremly well with the AE IB15 soundwise. The IB15 naturally goes deeper but that is really the only difference of significance.

As I said in another thread I will post some comparison between AE IB15, A&D R1524 and Eminence Alpha15. Some research is done but I couldn't finish before I went away, so I will come back on that subject.

/Erling

jacozz · « **Reply #53 on:** 27 Apr 2012, 10:44 pm »

Hi Scorpion!
The AD 1524 is really good, probably the best budget OB-woofer option.
Of course The the AE-speakers are in a different league, but it's cost makes me hesitate.

Nah, Not worth it.
I happy with the ultra cheap German/Chinesers
The magic is in the midrange/treble. (1772).

I´m going to burn my Visaton B200:s in my fireplace.

They are really CRAP! compared to the 1772:s!

/Jacozz

jonnoshore · « **Reply #54 on:** 28 Apr 2012, 02:31 pm »

Quote from: jacozz on 27 Apr 2012, 10:44 pm

Hi Scorpion!
The AD 1524 is really good, probably the best budget OB-woofer option.
Of course The the AE-speakers are in a different league, but it's cost makes me hesitate.

Nah, Not worth it.
I happy with the ultra cheap German/Chinesers
The magic is in the midrange/treble. (1772).

I´m going to burn my Visaton B200:s in my fireplace.
They are really CRAP! compared to the 1772:s!

/Jacozz

Hi Jacozz,

Those TB 1772 look really nice!... I want to see how open baffle performs in my room before I investigate this OB stuff any further. http://www.parts-express.com/pe/showdetl.cfm?Partnumber=264-893 A little video is here too.

I have just got myself 4 Eminence Beta drive units S/H for £90 in a DIY bass speaker cab from ebay so will have all the drive units to start a volks-build(2). If the build proves to satify my ears I will hae to re-evaluate things as I have a full active Naim set up... mind your the funds this would release may enable a lovely build with some AD drivers and the TB 1772's.

John

nicoch · « **Reply #55 on:** 29 Apr 2012, 05:49 pm »

Quote from: scorpion on 21 Apr 2012, 07:23 am

As I said in another thread I will post some comparison between AE IB15, A&D R1524 and Eminence Alpha15. Some research is done but I couldn't finish before I went away, so I will come back on that subject.

/Erling

Great idea Scorpion !

LFM · « **Reply #56 on:** 30 Apr 2012, 04:44 pm »

Hello Erling. I have been following your contributions to several threads in this circle and respect your opinions very much. I have observed that you are unimpressed with the performance of the Eminence 15 in open baffle especially compared to the AE IB 15. I just read in the Yield OB thread that the Eminence can be improved greatly by modifying it to improve so called "oil canning". Would you consider performing the suggested mods to increase rigidity and then comparing before and after with measurements and listening?...Albert

scorpion · « **Reply #57 on:** 3 May 2012, 07:40 pm »

I don't really know. Some report tremendous improvment with various damping material others are totally unimpressed by such measures.
If the problem is the high Q-value of the Eminence no damping will cure that. So I think it would be better to have a woofer which is playing alright
without any tweaking from the beginning. Like for instance the A&D R1524.

/Erling

Gothover · « **Reply #58 on:** 5 May 2012, 04:56 am »

Quote from: scorpion on 3 May 2012, 07:40 pm

I don't really know. Some report tremendous improvment with various damping material others are totally unimpressed by such measures.
If the problem is the high Q-value of the Eminence no damping will cure that. So I think it would be better to have a woofer which is playing alright
without any tweaking from the beginning. Like for instance the A&D R1524.

/Erling

Scorpion makes a good point. I would love to use the A&E IB-15 however found the driver to be cost prohibitive.

I was not aware of the A&D driver, I will check it out.

The Alpha 15 is a low cost driver that can sound great, but there are certainly better drivers available, that do not require mods to get work their best.

Scorpion, I love your project, and am intrigued by your mounting. NICE...

Dave

Vigoon · « **Reply #59 on:** 9 May 2012, 09:16 pm »

Dear Scorpion, belated thanks for your hint...(got a computer problem).They are also sold out at Spectrum Audio... The Visaton BG13-P8 offer however a good replacement.
It is the first time I build an OB, but I'm already in love...Anybody ever tried the Beyma 8AGN?
http://www.toutlehautparleur.com/largebande/beyma-8agn-p-1630.html
I'm a bit afraid the back is not as open as it should for a use in ob...
The Davis 170MRP also seems promising...
http://www.toutlehautparleur.com/large-bande/davis-acoustics-170mrp-p-1711.html
I'm planning some more, retaining the bass / medium-wide range principle which is working especially well...