Do you mean to tell me Jamo actually made GOOD speakers too?!?!?!?
Yes. Back in the late eighties and early nineties. The "Concert" series was good too. The Concert VII was an excellent speaker with push-pull bass drivers with the backs into different sized enclosures. Concentric ports with the middle one to the back (larger) chamber and the annulus to the front (smaller) chamber. I still have mine - bi-amplified too!
http://ianamillar.com/gallery/albums/hi-fi/inside_jamo.jpg
Basic Active Two-way Crossover « Ian's Projects
how exactly can you have a real push pull with different sized rear chambers/ independantly coupled. isnt that more like antiphase, rather than true isobaric or push pull bipole
EDIT NOW i see it...its just a fairly standard, 2.5 way isobaric design...
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Do you mean to tell me Jamo actually made GOOD speakers too?!?!?!?
Go and check out Jamo's R909's.
Definately worth a listen!
An externally hosted image should be here but it was not working when we last tested it.
I don't know what the "2.5" means but I thought isobariks had a sealed enclosure behind one driver and a driver in front of that radiating into the room with no port like this:
Isobaric speakers - Wikipedia, the free encyclopedia
The bass section of the Concert VIIs has no sealed enclosure. Both sides of the push-pull (coupled electrically out-of-phase) drivers are in ported enclosures. I don't know the name for that configuration and therefore don't know of any other speakers to use it. One chamber is tuned to 30 Hz and the other to 150Hz IIRC. No doubt the design is tuned for flat response. I measured mine from 150 Hz down to about 28 Hz - quite flat, but there is sudden roll-off below 28 - unlike the Oriels which just keep going beyond the usefullness of my SPL meter and ears. i.e. the room still shudders silently (apart from a bit of port wind noise) below 20 Hz to around 15 where I roll-off with a 36dB/octave Fc=15 Hz turntable rumble filter to save the drivers from over-excursion.
'The bass section of the Concert VIIs has no sealed enclosure. Both sides of the push-pull (coupled electrically out-of-phase) drivers are in ported enclosures.'
Isnt the front driver in a small closed box,,,certainly looks so from the pic, as the rear one only appear to be vented into the rear space and reflex loaded.
if not and i am wrong and both drivers are ported then it must be clamshell/pushpull 6th order bandpass design. and in that case, the i wouldnt buy them as transient response/group delay is awful in most cases.
Isnt the front driver in a small closed box,,,certainly looks so from the pic, as the rear one only appear to be vented into the rear space and reflex loaded.
if not and i am wrong and both drivers are ported then it must be clamshell/pushpull 6th order bandpass design. and in that case, the i wouldnt buy them as transient response/group delay is awful in most cases.
@ fury
sorry but the comb filtered sound of open baffles isnt for me, and 2 ways are about the best sound to driver compromise for me..this is only avoided by using 3 way designs...less crossover and drivers the better IMHO...if only a really truely 'flat' FR driver was around to choose from. fostexs just look too wobbly on freq response for me, and beaming makes things harsher still. i would avoid a 3 4 5 way at all costs if i ever BOUGHT a pair of speakers..in fact coaxials like kef uni q and 2 ways are al id ever buy...and even then its be a sad day that i didnt make them instead.
sorry but the comb filtered sound of open baffles isnt for me, and 2 ways are about the best sound to driver compromise for me..this is only avoided by using 3 way designs...less crossover and drivers the better IMHO...if only a really truely 'flat' FR driver was around to choose from. fostexs just look too wobbly on freq response for me, and beaming makes things harsher still. i would avoid a 3 4 5 way at all costs if i ever BOUGHT a pair of speakers..in fact coaxials like kef uni q and 2 ways are al id ever buy...and even then its be a sad day that i didnt make them instead.
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Look closely at the cross-sectional drawing. The front chamber vents via the annulus around the rear chamber port to the front baffle.
Here is a photo to clarify:
An externally hosted image should be here but it was not working when we last tested it.
The bass response is quite fast and dynamic in these speakers. I'm not saying that its the "best". They're "fun" speakers - not really hi-end and can be picked up quite cheaply second hand if you're lucky enough to find an owner willing to part with them. I'm a sealed subwoofer fan generally and know that there are different schools of thought on transient performance/group delay etc. amongst the various designs. But the Concert VIIs extend very deeply for their modest proportions without the need for 12 dB/octave compensatory EQ for the natural roll-off of a sealed enclosure below resonance and the enormous (potentially voice coil melting) power amp requirements that go hand-in-hand with that.
I recall years ago a friend brought over a CD called "Fievel Goes West" (or something like that - it was a dumb kiddy cartoon soundtrack) and the cannon shots frightened the @#$% out of me! It was like being hit in the chest with something.
Anyway, back on topic, I am keen to learn what the Oriel's bass drivers are. They are 8 inches with pressed metal baskets with a magnet of about 5 or 6 inch diameter. They measure in parallel about 2.9 Ohms DC so they would each be classified as 8 Ohms drivers. Here is a photo which shows a 1998 date code as well as the number 20275.
An externally hosted image should be here but it was not working when we last tested it.
Does anybody recognise these as old Vifas or something?
I want to know as I wish to put a Zobel across them - not to compensate for their impedance curve (which would have no peaks in the 20-100Hz "use" range), but to suppress the 200kHz oscillation of my crummy Class-D amp which is used in the bi-amp set-up to drive them and I need to know the voice coil inductance without having to measure it.
Look closely at the cross-sectional drawing. The front chamber vents via the annulus around the rear chamber port to the front baffle.
Here is a photo to clarify:
An externally hosted image should be here but it was not working when we last tested it.
The bass response is quite fast and dynamic in these speakers. I'm not saying that its the "best". They're "fun" speakers - not really hi-end and can be picked up quite cheaply second hand if you're lucky enough to find an owner willing to part with them. I'm a sealed subwoofer fan generally and know that there are different schools of thought on transient performance/group delay etc. amongst the various designs. But the Concert VIIs extend very deeply for their modest proportions without the need for 12 dB/octave compensatory EQ for the natural roll-off of a sealed enclosure below resonance and the enormous (potentially voice coil melting) power amp requirements that go hand-in-hand with that.
I recall years ago a friend brought over a CD called "Fievel Goes West" (or something like that - it was a dumb kiddy cartoon soundtrack) and the cannon shots frightened the @#$% out of me! It was like being hit in the chest with something.
Anyway, back on topic, I am keen to learn what the Oriel's bass drivers are. They are 8 inches with pressed metal baskets with a magnet of about 5 or 6 inch diameter. They measure in parallel about 2.9 Ohms DC so they would each be classified as 8 Ohms drivers. Here is a photo which shows a 1998 date code as well as the number 20275.
An externally hosted image should be here but it was not working when we last tested it.
Does anybody recognise these as old Vifas or something?
I want to know as I wish to put a Zobel across them - not to compensate for their impedance curve (which would have no peaks in the 20-100Hz "use" range), but to suppress the 200kHz oscillation of my crummy Class-D amp which is used in the bi-amp set-up to drive them and I need to know the voice coil inductance without having to measure it.
lol yes i saw the twin port inside a port...very cool looking. clam shell 6th order bandpass design, with the top driver being vented thru half the annulus, bottom driver 2nd port for 6th order alignment vented thru the bottom half of the annulus, 1st port tube thru the centre of port... LOL I get it! definitely NOT a 4th order BP though. It MAY be tuned flat to compliment the bass/mid drivers rolloff, but 6th order BP are so finicky with tuning and TS values i doubt it is. Not for me, but then i prefer SQ to chest hitting lumps in bass, and the car sub sound is not my cup of tea. But each to their own. maybe with a DCR of 2.9 Ohm then they are in fact 6 Ohm drivers? Like Audax and many(im sure) other manufacturers have and do produce. Without looking at the face of the driver or some codes then its not going to be all that easy to work out what drivers they are...at least not for me, or unless a serious Jamo nutter is out there to comment on them. I would be surprised if they were Vifa and werent their own OEM design.
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Still wrong. i=In the Concert VII, the top driver is a sealed midrange (150 to 3500Hz). The whole annulus vents the front bass chamber. The centre port vents the rear bass chamber. I think I agree with you that its called 6th order bandpass. The only confusing part is that the ports are not located remotely of each other. I have measured flat (give or take a few dB) in-room response from 28 to over 150 Hz. A good room. That was with no signal to the midrange and no other filter to the direct-wired bass drivers (i.e. no cross-over either passive or active in the system).
Thanks rjb. I'll have to seek that out at the library.
Today I traced out the passive tweeter crossover circuit for the Oriel and it is very complex. It has such a large parts count that I think it may have some kind of phase shift built into it to compensate for midrange/tweeter driver offset. Here it is:
An externally hosted image should be here but it was not working when we last tested it.
This complexity may have an adverse affect on the tweeter sound quality (Dynaudio Esotar). Mine does not sound brilliant despite the comments on other sites about how good it is and has put a dampener on my idea to upgrade the midrange to a new ScanSpeak Illuminator (if it is not too deep to fit) which I have simulated with WinISD to have a flatter response (bit higher at the tweeter crossover point though) than the standard Eton Hex (estimated sealed chamber volume of 21 litres for ideal Q). Actually the old Revelator has an even flatter simulated response in this "estimated" volume. I wouldn't know where to start on that passive crossover circuit to reduce attenuation (well R4 looks like a likely place but what about R2?). A better solution might be to direct wire the tweeter and actively tri-amp with an opamp phase shift on the line level tweeter output (there is an ESP article on it) with a nice little Class-A amp on the tweeter. Oh no! I think I know what I'm going to be doing for the next few months!!
I'll find that article first though. It will no doubt have a lot of good info. Thanks again rjb.
Yes there is a Zobel across the midrange, but those CO frequencies don't look right. AFAIK they are 100Hz and 3K (which is about the useful range of the Eton Hex midrange). I am actively bi-amping and crossing from the woofers at 102Hz and it is smooth.
Addendum: It seems my Oriels are 1998 production so maybe there were changes. The cross-over from bass to mid in mine were 2nd order.
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can you take a picture of the woofer?
From the age of the thing it could be a Peerless from the CCX or CCS range.
Those widely used woofers had a poly conde with a cloth or paper dome shaped dustcap.
(like the CCS-220/8)
http://www.madisound.com/catalog/PDF/831858.pdf
http://www.lautsprechershop.de/hifi/index_en.htm?/hifi/peerless_en.htm
From the age of the thing it could be a Peerless from the CCX or CCS range.
Those widely used woofers had a poly conde with a cloth or paper dome shaped dustcap.
(like the CCS-220/8)
http://www.madisound.com/catalog/PDF/831858.pdf
http://www.lautsprechershop.de/hifi/index_en.htm?/hifi/peerless_en.htm
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Thank you very much. I shall investigate. I wish I could get a photo from the front of the cone but the woofers are deeply sealed within and I haven't found a way to open the Oriels right up. There is a picture of the back of one of the bass drivers higher in the thread which I was able to take by removing the crossover "hatch".
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Jamo Oriel
Hello Ian,
I just bought a pair of second hand Oriel loudspeakers in PERFECT shape, but the seller could not provide me the Owner's Manual - he said he lost it, and I do not know how to connect the bridges between the binding posts (I intend to single wire them).
Is there any possibility for you to scan your Oriel's Owners Manual and set it to me thru email, please? In exchange, I can send you the original service manual for Oriel, if you need it.
My email address is eduard.lapas@yahoo.com
Thank you in advance!
Best regards,
Eduard Lapas
Hello Ian,
I just bought a pair of second hand Oriel loudspeakers in PERFECT shape, but the seller could not provide me the Owner's Manual - he said he lost it, and I do not know how to connect the bridges between the binding posts (I intend to single wire them).
Is there any possibility for you to scan your Oriel's Owners Manual and set it to me thru email, please? In exchange, I can send you the original service manual for Oriel, if you need it.
My email address is eduard.lapas@yahoo.com
Thank you in advance!
Best regards,
Eduard Lapas
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