[ttan98]

I brought the speakers to a DIY-show in Stockholm last weekend, they made quite an impact I would say ! 

/Erling

Good for you!   and thanks for your response...

[scorpion]

It was not really good for me for that reason because this was the only OB speaker presented. That's why the overall response was so encouraging. Both bass and the fullranger spectrum was considered very good. Especially I think people were surprised by the bass response.

/Erling

[Deda]

@ scorpion

What exactly was wrong with Klang & Ton dipole design except them having bad FR units? Choice of bad bass drivers or something else?

[scorpion]

The Monacor SP-130X/8 measured so bad so they should have checked this before publishing. Monacor complained and there was a hide away correction in a later issue. In fact with good units they did simplified the crossover design. But the damage was alread done. The SP-130X/8 is really worth a better faith. I have been using 4 different SP-130X/8 units no one has had any response failure. The SP-130X/8 has for a fullranger a remarkably flat frequency response up to 20 kHz.

As my design proves they could have done better than choosing two additional Monacor bassunits for each channel inferior to the A&D 1524 thereby tripling basscost and loosing about 10 dB in efficiency by inefficient dipole design. This might be a matter of taste but as you can see my design is 40 cm (16") wide and K & T's 45 cm (18"). Their design is 50 cm (20") deep mine is 30 cm (12")

Another design feature is the rounded baffle top which will affect response badly as easily could be simulated with for instance the Edge software: http://www.tolvan.com/edge/ .

One thing that I shall add: You cannot take my design and do it any other way. I seem to have overlooked to state wall thickness. This is 18 mm (.71").
This enclosure is by itself extremly light, made from Spruce only. You have to secure elements my way. This is for the least vibration sensitivity. Still the enclosure 'sing a long' abit. But as it seems 'Mother of Tone' is perhaps more right than wrong in their assumptions. I am still more than amased by the tonal output of these speakers and they do bass. One comment from my bringing them to the DIY-show in Stockholm was a forum writing 'run out and buy' (and I suppose build this speaker).

/Erling

[SamL]

Hi Erling,

Did you manage to use passive crossover on your Volks-OB? How does it compare to Active?

Sam

[Anglo]

Hi

I have read through the thread, and if I missed it I am sorry, but where does the "patent" with blind cord get explained?

[scorpion]

I am sorry for the late reply, but after March 18th I have not been able to attach to the Audio-Circle because of a conflict between my Swedish ISP and Cogent, USA.
That's a bad state of affairs. This answer is going via my son who has another ISP with no problem. I am afraid it will be kept short.

About my 'patent' speaker mounting method. That's of course no patent but a search for a simple alternative to magnet mouting. The point is to transfer as little as possible of speaker vibrations to the baffle. I have used Venetian Blind cord attached to the back chassis legs to fasten elements to the baffle. Elements rest on a strip seal bed. It should be pretty clear from the photos in this thread and in the 'Wide Open Venetian Blind' thread how I have done. The 'Volks-OB' spruce baffle is however very light only 18 mm thick so some vibrations are still carried over. It may be that the strip seal is to frictional so I am at the moment experimenting with other materials. I have great hope in 'under floor step damper' material which I think has less friction and also isolates from vibration. Anyway I am very pleased with the performance of these speakers as they stand now. Spruce by itself may contribute positively as some argue.

Regarding the passive crossovers: A Big surprise. They don't take away anything from the active solution. They go low with exellent performance, bass units recommended, and for the highs
Obbligato capacitors from DIY Hi-Fi Supply should rank with the best there are, I think: http://www.diyhifisupply.com/diyhs_ob_caps.htm . Making possible a real high performance budget speaker.

For the moment I don't listen to any other speaker and I have both Magnepan 1.6, the B200 and Ciare CH 250 to choose instead. In fact there is a great similarity between the Volks-OB's Monacor SP130X/8, the B200 and the Ciare CH-250 in tone (strange: you could easily interchange between any of them in a stereo pair), all are very good speakers, but it is only the Monacor which doesn't need external correction. The 'Volks-Ob' as it is described here is without any doubt the most satisfying as a complete speaker even if it is a FAW (fullrange and woofer in Rudolf's terminilogy).  But I have some more projects coming up.

/Erling

[Russell Dawkins]

can't find the SP 130 X/8 on the Monacor site

similar, but not exactly.

[scorpion]

Regarding Monacor 130X/8 thats not so surprising because it is hidden long away from the fancy elements: http://www.monacor.de/typo3/index.php?id=59&act=8&act_sub=25&L=0&typ=u&hkatid=62&ukatid=882&spr=DE&brand=MO&seiten_id=25&produktliste=59
 
Hope it helps !
 
/Erling

[Russell Dawkins]

Thanks, Erling.

One question occurs to me.
I know that crossing over to the Monacor at 300Hz does help power handling, but according to the data sheet the moderate power handling and efficiency of the Monacor unit  suggests a peak loudness capability of approximately 103 dB. Can you play orchestral music at realistic levels with this speaker?

I am not talking of the 1812 Overture!

[scorpion]

Russel,

Well, 95 dB is no problem but complex music at 100 dB can be tricky.
But my main listening is in the 80 - 90 dB range.

I have in fact been contemplating putting two SP130X/8s on the baffle but that is also something which is dependent of
that I usually drive this speaker with a Trend 10.1 which is limited at 8 ohms.

/Erling

[scorpion]

I have been forwarding this speaker a bit. It now uses two SP130X/8s in parallel to further SPL and taking more power and also to be better suited to my small Trend amp with a more forgiving total impedance. The crossover is just modified for the fullrangers 4 ohm impedance. It is as earlier L-R 12 dB/octave but with values 70 uF Obbligatos and 4.4 mH and works beatifully. The 3.3 ohm resistors are taken away, the sensitivity of this setup is around 95 dB/1 watt. Playing the Manger test-record 'Musik wie von einem anderen Stern' track 15 - a Percussion group with extremly tight bassdrum parts I really need my NAD 216 SS-amp to produce 105 dB in those passages and it does move the basscones a bit. Both the Trend and a PP 30W Tube amp distorts heavily when tried to go this high.
So for bass you need power. But the good story is also that the fullrangers as set take this power without any sign of stress. The integration between the fullrangers mounted close to each other vertically is no problem. The overall sound is still way beyond expectations. 

/Erling

[fergs1]

Greetings Erling, so forgive me for being off topic but what do you use to correct the b200 (including components and their values) I tried just the 1h and 8 ohm coil and resister that a lot of people here have tried but didn't like it. Its seemed to suck a big hole out of the music. Would appreciate any advice regarding correcting the b200
                            cheers  fergs

[scorpion]

Hi fergs1,

Sorry, I have been away a couple of days. Who is fergs2 ? I think you have to live with some action for the b200. I run it totally active nowadays with a digital filter closely mimicing the pseudo 'baffle step filter' of 1mH and 8-15 ohm resistance but coming back over 10 kHz. I really noticed a drawback with passive components contra active equalizing. But that is a matter of habit and taste. Myself I am going to try an approach suggested by Graham Maynard here in OB circle of letting a similar  speaker fill in the response of the b200 under 1.5 kHz. That's an interesting ideea whose success might follow !

/Erling

[scorpion]

With regard to how this speaker actually performs I will complete with some additional notes about 'Volks-OB' MK II.

Here is the 'Volks-OB' compared to my Magnepan 1.6. These speakers are very much like each other in sound. To my ear the 'Volks-OB' wins with a bit more open and direct sound when speakers are calibrated to the same SPL. But that is mostly a matter of taste. And, yes, it as good as ....  .



Left and right speakers are mirror copies. Main baffle 44 x 16" with A&D R1524 10" up from floor middle placed. SP 130x/8s 6" in from the side and placed 33.1 and 38.6 " above floor. Picture is of the right hand speaker. Speakers are built with Spruce panels, wings not visible on this picture

As this is a 'Volks-OB' here is also the crossover characteristic and build:





Anyone should be able to build this speaker !

/Erling

[Graham Maynard]

Sorry to intrude on the 'Volks' here Erling.

Hi Fergs, 

If the choke+resistor effect is too severe, then you could try reducing the resistor value to acheive a compromise. 
Actually it might be better to fit a Zobel when you insert series components;  say 1uF and 5.6 ohms in series conected directly the the LS teminals. 
The B200 beams and disproportionately concentrates HF, so do try foam fingers to disperse the beam. 
This driver also benefits from the fitment of a series choke to overcome sibilance, say 50 to 100uH.
You can wind this choke youself with say 50 to 100 turns of ordinary thin connecting wire wound over the cardboard tube from inside a kitchen or toilet roll, or over the ferrite bar antenna from a broken AM radio.  Easy to adjust the number of turns too !
 
Cheers ........ Graham.

[panomaniac]

Nice!   I see that you are also a fan of the Obbligato oil caps. =)  Sweet....

How do the two 5" FR drivers get along?  Doesn't sound strange?

[scorpion]

Hi Pano,

No you have go real near to hear any of the fullrangers for themselves. About the sound as such, it is really good. I would without any doubt recommend these speakers to anyone wanting a quality hi-fi-speaker. I think the Obbligatos are a real find.

This is a quote from Swedish Hi-Fi Forum and one of its moderators, who have heard the speakers on a DIY-show in Stockholm:
'Jag kan intyga att de här spelar fantastiskt bra för den mycket låga kostnad som vi talar om här. Bygget är ju dessutom ganske enkelt så många som letar billiga högtalare borde följa den här tråden NOGA.' Translated: 'I can assure that these (speakers) play fantastically good for the very moderate cost we speak of here. The build is also quite simple so many who are looking for cheap speakers should follow this thread CAREFULLY'.

Link: http://www.hififorum.nu/forum/topic.asp?TOPIC_ID=69417

I usually play these speaker with a Trends 10.1 T-amp modified by your suggestions, Pano, even RFI-stoppings. MK I had one Sp130X/8 but then I had to take down bassoutput about 3 dB and also the Trend occasionally went inte distortion when playing loud soprano-chor tunes for instance. So I decided to go over to two SP130X/8s and that has turned out really well. No bass takedown and much better 4 ohm response from the Trends.

In fact, I am amazed myself over the performance of this 'Volks-OB'. 

/Erling

[Rudolf]

Hi Erling,
I wonder, if reversing one of the SP 130x/8s (radiating to the back) does make any difference. Theoretically it should help to make the in-room-power of the highs more equal to the direct radiated power. Practically it could be BS, but if you happen to have a srewdriver at hand .... 

[scorpion]

Hi Rudolf,

Because of my build I had to reverse left and right upper 'floor' like in the picture here:



I am listening to Beethovens 5th, I think you are right. But the difference is not so striking. Looks are a bit weird, but sound might in fact be a bit better.
Perhaps I should also mention that I have put Bitumen to all outside parts of the SP130X/8. I think it helps.
On the inside of the SP130X/8 chassies there are felt applied to all surfaces.

In fact it is very interesting to listen to this setup. It might be a little bit more 3dimensional. However you have to weight looks and perfomance.

/Erling