Does anyone know what 6.5"/170mm bass driver PMC uses in their OB1 speaker? It looks like it could be a Peerless 830946 or possibly a Morel HU631. PMC's web site says it is a doped 170mm driver with cast magnesium chassis. This would indicate to me that this is a paper coned woofer. Also, PMC seems to like using the Typhany Group's (Vifa, Peerless & Scan-Speak) drivers. Any suggestions? I have already selected the Scan-Speak R2904/7000 tweeter & ATC SM75-150S midrange and am now trying to pin down which woofer to use. Any ideas are more than welcome. I am using Martin King's transmission line tables to help out with the design. Has anyone used them before? They look like he really knows what he is doing.
Thanks to all,
John
Thanks to all,
John
Thanks for your reply.
I have emailed ATC and Solen (ATC's Canadian distributor) to see if there is any way to beg, borrow, or steal a pair of the 170mm drivers used in the ATC SCM40 speakers. I think that this might well do the trick. I need to keep the speakers as narrow as possible to improve the spousal factor or I would try to use an 8" or 9" bass driver.
Thanks again,
John
I have emailed ATC and Solen (ATC's Canadian distributor) to see if there is any way to beg, borrow, or steal a pair of the 170mm drivers used in the ATC SCM40 speakers. I think that this might well do the trick. I need to keep the speakers as narrow as possible to improve the spousal factor or I would try to use an 8" or 9" bass driver.
Thanks again,
John
Take a serious look at the Hi-Vi D8.8+, it would do very nicely as a bass driver with an xover anywhere up to as high as 1.5KHz. Its a very, very good driver but with an affordable price tag 
I also feel that both the tweeter and the midrange you mention are over-priced for the performance on offer. I would likely go for either the Vifa XT25 or more likely the recently announced Peerless 810921 which looks absolute irreproachable for the money, having performance on par with the best there is.
As for midrange I guess there is not a huge choice. The ATC is good, but is pricey. Volt do a midrange unit but its not on their site. PMC actaulyl use this with some slight mods in their big boys speakers Give Volt and email.
I also feel that both the tweeter and the midrange you mention are over-priced for the performance on offer. I would likely go for either the Vifa XT25 or more likely the recently announced Peerless 810921 which looks absolute irreproachable for the money, having performance on par with the best there is.
As for midrange I guess there is not a huge choice. The ATC is good, but is pricey. Volt do a midrange unit but its not on their site. PMC actaulyl use this with some slight mods in their big boys speakers
Give Volt and email.ATC's 180mm bass driver is not for sale. They want to keep it for themselves. According to Solen, the Morel HU631 is not up to the quality of the SS R2904/7000 and ATC SM75-150S. Solen is recommending an Audio Technology custom built driver. This sounds like a pretty cool way for the hobbiests to pretend they are speaker manufacturers. You select your driver size, magnet size, voice coil diameter, coil height, gap height, desired fs, Qts, Vas & Qmin and 'voila!' they build you a driver. See http://www.audiotechnology.dk/iz.asp?id=4|a|119||| for more info. It turns out these guys started Scan-Speak & Vifa, among others. I am just starting out in the custom order process but I'm excited to see how it works. Solen has been very helpful with various questions I have had regarding desired parameters, etc. This is usually a process reserved for manufacturers.
Thanks,
John
Thanks,
John
Sorry for the thread resurrection but better to continue than start again and keep all info in one place.
Anyway, been looking into this one as there is quite a bit of info out there to make a clone of this fine speaker (cross sections that can be scales etc.).
Anyway from a quick goggle it seems the drivers are -
Tweeter - PMC special version of Seas 27TFFC (stock version available)
Mid - 3" dome Scanspeak Discovery D7608/920010 (available)
Bass - 6.5" woofer Vifa M17WG-09-08 (unavailable).
Crossover : "380Hz and 3.8kHz, with a filter 24dB/oct; those are Linkwitz-Riley filters." from High Fidelity
A quick search for a similar spec driver trying to keep most of the Small Theil parameters the same came up with the Seas CA18RLY-08 H1217
The parameters seem to be pretty close (Vifa - Seas)
http://www.sea.vg/vifa/M17WG-09-08.pdf
http://www.seas.no/images/stories/prestige/pdfdatasheet/H1217_CA18RLY_Datasheet.pdf
Fs - 44hz - 42hz
Vas - 34l - 32l
Imp - 8/5.5 ohm - 8/5.8 ohm
Sd - 143cm2 - 136cm2
Qms - 2.77 - 2.92
Qes - 0.56 - 0.56
Qts - 0.46 - 0.47
MM - 11g - 10.6g
Sens - 89db - 90 db
The frequency plots also look similar except for the Seas hanging on a bit lower but they both have a rise at around 300hz.
So, potentially with the Seas bass river this could be a fairly economical way to come up with an OB1 clone - UK prices for driver seem to be about Tweeter £40, Mid £70, Bass £65 (inc vat).
If I get chance I will try and put this through Boxsim but this will only be for a BR set up not a TL but will give an idea if a fairy basic crossover may work.
Any comment on this alternative driver would be appreciated.
Anyway, been looking into this one as there is quite a bit of info out there to make a clone of this fine speaker (cross sections that can be scales etc.).
Anyway from a quick goggle it seems the drivers are -
Tweeter - PMC special version of Seas 27TFFC (stock version available)
Mid - 3" dome Scanspeak Discovery D7608/920010 (available)
Bass - 6.5" woofer Vifa M17WG-09-08 (unavailable).
Crossover : "380Hz and 3.8kHz, with a filter 24dB/oct; those are Linkwitz-Riley filters." from High Fidelity
A quick search for a similar spec driver trying to keep most of the Small Theil parameters the same came up with the Seas CA18RLY-08 H1217
The parameters seem to be pretty close (Vifa - Seas)
http://www.sea.vg/vifa/M17WG-09-08.pdf
http://www.seas.no/images/stories/prestige/pdfdatasheet/H1217_CA18RLY_Datasheet.pdf
Fs - 44hz - 42hz
Vas - 34l - 32l
Imp - 8/5.5 ohm - 8/5.8 ohm
Sd - 143cm2 - 136cm2
Qms - 2.77 - 2.92
Qes - 0.56 - 0.56
Qts - 0.46 - 0.47
MM - 11g - 10.6g
Sens - 89db - 90 db
The frequency plots also look similar except for the Seas hanging on a bit lower but they both have a rise at around 300hz.
So, potentially with the Seas bass river this could be a fairly economical way to come up with an OB1 clone - UK prices for driver seem to be about Tweeter £40, Mid £70, Bass £65 (inc vat).
If I get chance I will try and put this through Boxsim but this will only be for a BR set up not a TL but will give an idea if a fairy basic crossover may work.
Any comment on this alternative driver would be appreciated.
The Vifa M17WG-09-08 certainly has been used in some PMC speaker models, but the woofer of the OB1 has a huge dust cap of 3.5". I rather would assume Dynaudio, Morel or a custom driver.
PMC OB1i or OB1 Signature Woofer Spare Photo #1503144 - Aussie Audio Mart
PMC OB1i or OB1 Signature Woofer Spare Photo #1503144 - Aussie Audio Mart
Doh - School boy error - look at the pictures !!!
The link to pictures @Dissi posted are interesting as the speaker suspension only has 4 legs and the cross section (C or H) is very similar to the Vifa ones. A bit more digging shows the Vifa M17WG was used on the PMC FB1, (This site gives details of FB1 dimensions and crossover HIFIDIY??-??DIY?VIFA M17WG-09?? - Powered by Discuz!) , is it possible that they just changes the centre cap for the OB1 ?
The OB1 is stated as having a line length of 3.3m, so using the MH Audio transmission calculator with the M17WG parameters give:
mh-audio.nl - Home
A line length at Low frequency tuning (1/3 wave) of 227cm, port height of 11.9cm and a Fb of 30hz. This obviously does not match up with the PMC dimensions. (used 16cm internal width, 200mm as stated minus approx 20mm for cabinet walls)
So, I know the Scanspeak Discovery 18W/8542-00 is a bit of a favourite on here so I though I'd do come calcs. Using the Ml calculator you get:
A line length at Low frequency tuning (1/3 wave) of 302cm, port height of 15.6cm and a Fb of 23hz. This obviously is a closer match up with the PMC dimensions.
Now putting this through the DB Dynamix single folded front port calculators, you get:
Single Fold On-Axis Transmission Line Enclosure Calculator - DB DYNAMIX AUDIO
A recommended line volume of 1.6ft2 and a calculated volume of 1.56ft2 with a tuning frequency of 43hz. (5.5 in port height, which gives about the right speaker depth, all other dimensions as per PMC data).
This speaker looks like it would work nicely but with an increase in cost (18W is approx £140). So, is there any other TL style kits that use the 18W driver?
The link to pictures @Dissi posted are interesting as the speaker suspension only has 4 legs and the cross section (C or H) is very similar to the Vifa ones. A bit more digging shows the Vifa M17WG was used on the PMC FB1, (This site gives details of FB1 dimensions and crossover HIFIDIY??-??DIY?VIFA M17WG-09?? - Powered by Discuz!) , is it possible that they just changes the centre cap for the OB1 ?
The OB1 is stated as having a line length of 3.3m, so using the MH Audio transmission calculator with the M17WG parameters give:
mh-audio.nl - Home
A line length at Low frequency tuning (1/3 wave) of 227cm, port height of 11.9cm and a Fb of 30hz. This obviously does not match up with the PMC dimensions. (used 16cm internal width, 200mm as stated minus approx 20mm for cabinet walls)
So, I know the Scanspeak Discovery 18W/8542-00 is a bit of a favourite on here so I though I'd do come calcs. Using the Ml calculator you get:
A line length at Low frequency tuning (1/3 wave) of 302cm, port height of 15.6cm and a Fb of 23hz. This obviously is a closer match up with the PMC dimensions.
Now putting this through the DB Dynamix single folded front port calculators, you get:
Single Fold On-Axis Transmission Line Enclosure Calculator - DB DYNAMIX AUDIO
A recommended line volume of 1.6ft2 and a calculated volume of 1.56ft2 with a tuning frequency of 43hz. (5.5 in port height, which gives about the right speaker depth, all other dimensions as per PMC data).
This speaker looks like it would work nicely but with an increase in cost (18W is approx £140). So, is there any other TL style kits that use the 18W driver?
Been playing around with Leonardo's TL calculator and a model of an OB1.
I have modelled a SB 23MFCL45-8 (8" mid range £ woofer/subwoofer) with the same geometry as the OB1 (as close as I could guess from various internet pictures) including the inclusion of a reduction due to the Mid driver enclosure. And the results look pretty good if you heavily (?) pack the TL out with stuffing at between 5 and 9 Kg/m^3 (0.3-0.56 lb/ft^3) to get rid of the higher frequency wrinkles (is this stuffing possible/appropriate?). I have added a 380hz 24db/octave low pass as per the OB1. This give a s nice f3 of 24hz and a f10 of 20hz.
Here is a screen shot of the TL calculator input/output and the SB data sheet. Can anyone verify that I have done this right - TL is 2.33m long and starts at 500cm^2 reduced to 150cm^2 at the mid driver (5" tube) and back up to 350cm^2 and finally down to 200 cm^2 at the exit. 22cm wide box give a volume of 73litres. I did re-organise this to be in the same orientation as the speaker but it made very little difference to the response.
Thinking of adding a W4-1337SD (the neo one with the small magnet) as the mid and then not sure on tweeter yet but the Satori TW29BN looks nice.
Comments/thoughts welcome.
I have modelled a SB 23MFCL45-8 (8" mid range £ woofer/subwoofer) with the same geometry as the OB1 (as close as I could guess from various internet pictures) including the inclusion of a reduction due to the Mid driver enclosure. And the results look pretty good if you heavily (?) pack the TL out with stuffing at between 5 and 9 Kg/m^3 (0.3-0.56 lb/ft^3) to get rid of the higher frequency wrinkles (is this stuffing possible/appropriate?). I have added a 380hz 24db/octave low pass as per the OB1. This give a s nice f3 of 24hz and a f10 of 20hz.
Here is a screen shot of the TL calculator input/output and the SB data sheet. Can anyone verify that I have done this right - TL is 2.33m long and starts at 500cm^2 reduced to 150cm^2 at the mid driver (5" tube) and back up to 350cm^2 and finally down to 200 cm^2 at the exit. 22cm wide box give a volume of 73litres. I did re-organise this to be in the same orientation as the speaker but it made very little difference to the response.
Thinking of adding a W4-1337SD (the neo one with the small magnet) as the mid and then not sure on tweeter yet but the Satori TW29BN looks nice.
Comments/thoughts welcome.
An externally hosted image should be here but it was not working when we last tested it.
The reduction in area is to model the mid driver enclosure in the OB1 that cuts through the transmission line. This is a plastic closed tube. if you play around with the model it does not make a lot of difference. PMC seem to use the Driver being art way up the TL to reduced the ripples in the upper bass.
Image here - OB1のカットモデル: koulog
Approx dimensions can be seen here - Zaph ZDT3.5 in ATL config
I have tried to attach the Leonardo file, let me know if you can read it. You will need to change the extension from .txt to .tlp before using it the software.
Hope this helps.
Image here - OB1のカットモデル: koulog
Approx dimensions can be seen here - Zaph ZDT3.5 in ATL config
I have tried to attach the Leonardo file, let me know if you can read it. You will need to change the extension from .txt to .tlp before using it the software.
Hope this helps.
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I've loaded finally in my idiotic windows10. Seems that reduction doesn't cause any change. I think you can remove it. Then try to delete all stuffing and move driver little bit right. You will see that first ripple almost gone. After that add stuffing. Yesterday I first time loaded this sw Leonard so I don't have much experience. If you want to be sure ask MJKing he is expert for TL.
Thanks, issue with moving the driver right (upwards in the actual speaker) is that is where the mid driver in the OB1 sits. If I were going to make this I would like to keep it a three way with the mid close to the tweeter. Here is a picture of the same model but folded in actual position with the front of the speaker on the left i.e. as in the OB1 with the TL exit as a front port and the mid driver where the reduction in cross section is.
Attachments
I think you can remove reduction just to not produce confusion. It looks fine and SPL is perfect from 30Hz until almost 300Hz. Actually stuffing most dictate SPL curve regarding ripple reduction. I don't have experience if it is possible to put so much. This is much more than heavy in Leonard sw.
I found the Leonardo stuffing guide a bit off putting as well. This link -
Classic TL Design -- Jon Risch
say a stuffing density of around 0.5-0.7lb/ft3 which converted is approx 8-11kg/m3 so looks like I was in about the right zone. Also other suggest only stuffing the first 2/3rds of the line. Again, interestingly that PMC do not stuff at all but use a foam liner to dampen any standing waves.
Thanks for looking at this and confirming that the calcs were in the right ball park.
I did model a few more speakers, the Dayton RSS210HF-4 also gave some good results but needed some geometry changes (just reduced the final element to 100cm2 at both ends). My only concern are that the Dayton and the SB23 are subwoofer speakers rather than large woofers, not sure how that would effect upper frequency break up and therefore cross over with the mid range (approx350-400hz).
Classic TL Design -- Jon Risch
say a stuffing density of around 0.5-0.7lb/ft3 which converted is approx 8-11kg/m3 so looks like I was in about the right zone. Also other suggest only stuffing the first 2/3rds of the line. Again, interestingly that PMC do not stuff at all but use a foam liner to dampen any standing waves.
Thanks for looking at this and confirming that the calcs were in the right ball park.
I did model a few more speakers, the Dayton RSS210HF-4 also gave some good results but needed some geometry changes (just reduced the final element to 100cm2 at both ends). My only concern are that the Dayton and the SB23 are subwoofer speakers rather than large woofers, not sure how that would effect upper frequency break up and therefore cross over with the mid range (approx350-400hz).
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Thanks, that would be the plan, to copy the OB1 with a closed mid around 2-3l using the TB W4-1337sd (neo magnet version as used in the Satement series speakers). Tweeter would be either the SB 29RDC ring or possibly the 26ADC metal dome or 26CDC ceramic dome or possibly the Fountek NEOCD3.0 ribbon crossed at 3500-4000hz.
A very quick sim using Boxsim for the RS210HF-4 plus w4-1337 and SB21RDC using active filters at 24db (4th order) and then adjusting the gain in a 65l box tuned to 25hz give a pretty decent first stab (approximates the TL). Note that the tweeter and mid will need significant pads to reduced to woofer level. Will have a go at a passive crossover at some point but looks promising and points towards a true 20hz to 20khz box.
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First post, please do crucify me if I'm not supposed to resurrect old threads
but I'm particularly interested if Ugg10 ever got round to building sth?A little over 10 years ago I was fortunate enough to audition the OB1i's in my apartment for a few weeks. "'t was like angels peeing in my ear" I recall thinking back then. Didn't end up buying them as the financial crisis was gathering steam so ended up deciding it wasn't wise to spend ~ EUR 5.000 on loudspeakers. Good call!
Lost my job in finance, other opportunities came but never the discretionary income combined with right time and place to justify such an expenditure, and it seems PMC TL's only got more expensive since. I've listened to 2-way TL kit (Scan Speak Event) at a diy store before corona hit which confirmed for me again potential of TL (I liked it more than all the way more expensive kits, so probably I have strong preference for TL bass). I also know from comparing PMC FB1i to OB1i in store ~10yrs ago that it has to be 3-way for me. However, I haven.t found too many 3 way TL diy designs. Hence, researching what it would take to build something of comparable quality to OB1i.
So Ugg10 did you get round to building a 3 way TL at all? If not, how far did you get? Reasons for continuing / stopping?
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