Supravox

[red76]

Hello OB fans,

Just saw this site update from Supravox America....

http://www.supravox.com/news.html

[Doc Jr 8156]

Nice! I was looking at this last night, what a coincidence.The only problem with this is that you need almost $4000 to try it. That's only for the cost of the drivers! Who knows? Someday. Godspeed.

[Doc Jr 8156]

Red,
A follow up question. The Supravox 215 (OB) has a low Qts of .23. Is this the reason why they added the woofer? The least costly Supravox driver has a Qts of .8, will this work in OB? Godspeed.

[red76]

The only problem with this is that you need almost $4000 to try it. That's only for the cost of the drivers!

Hi Doc,

You don't need $4k to take advantage of this simple OB design , there are very good but more affordable widerangers, midranges, and woofers suitable for this design. Anyways, quality plywood pieces and piano type hinges are all that's needed for an enclosure. Kulang nalang karpintero.

The Supravox 215 (OB) has a low Qts of .23. Is this the reason why they added the woofer?

No.

With the 215-2000EXC excitation magnet, the Qts can be lowered (at the expense of some efficiency tho). And if you read the newspage, it says that it was redesigned for OB apps - so there is now a variant called 215-200EXC-OB... The V and A settings of the field coil supply are crucial for variable T/S, and hence you can tailor the sound - you need DC psu's of the drivers. The standard Alnico 215-2000's are not really intended for OB, but they could work, although I speculate they would be less effective than some of the other drivers in the line-up. Try to check www.supravox.fr (French homepage) for complete datasheets, graphs, etc. FWIW, if you look at the 400-2000 Woofer datasheet the Qts is actually 0.27. Whereas the EXC version can again, vary.

The least costly Supravox driver has a Qts of .8, will this work in OB?

Yes, it definitely would if you are refering to the 215 Signatures (Bicone and Non-Bicone). However, they are not the least costly at almost 230.00 Euros each for the Non-Bicone (really needs tweeters).

[Doc Jr 8156]

Red,
Thanks. What other drivers (not as expensive) can I investigate? Visaton? pHY? The Bicones are really looking good eh? I'll try them someday. Godspeed

[ichabod]

While you're looking, I've learned that Hartleys make full range drivers. Vintage speakers they are. So they could well be in the league of the Weco 755As, the later altec versions, RCA's LC1s (this I believe is a 15 incher saw one lately), and who knows maybe the "saba," "telefunken," Siemens klangfilm, isophons are just as well firm contenders for OB use. Maybe those of you who may have heard or own these speakers can speak up and fill us in.

[joe3rp]

Qts ? what parameter is this a measure of? The ability of the driver to return to center/rest? The lower the Qts value means a slower return to center?

[red76]

While you're looking, I've learned that Hartleys make full range drivers. Vintage speakers they are. So they could well be in the league of the Weco 755As, the later altec versions, RCA's LC1s (this I believe is a 15 incher saw one lately), and who knows maybe the "saba," "telefunken," Siemens klangfilm, isophons are just as well firm contenders for OB use. Maybe those of you who may have heard or own these speakers can speak up and fill us in.

Hartley STILL makes FR drivers and woofers. They don't have a website and operate in a very low profile. Sunlight Engineering (near LAX) also makes widerange and Coaxial drivers (very $$$). Most of those German made FR's and woofers are suitable for OB use (old theater stuff), and some aren't that pricey (ebay, etc.) except those specialy made VEB type alnico and older field-coil like RFT and Graetz, and of course the better known Klangfilm/Siemens Telefunken auctions I've seen that went through the roof. Some old console drivers are good too although less efficient and not as robustly built. Don't forget those vintage Japanese drivers like what setup1 posted. I own a paif of them Japanese stuff and sound good with resonant cartons as mockup baffles (drivers placed on chairs)!

Qts ? what parameter is this a measure of? The ability of the driver to return to center/rest? The lower the Qts value means a slower return to center?

Joey,

Here's a useful list. T/S:

A Attenuation, loss of db
B Magnetic flux density in gap
Bl Electro-magnetic force factor
BL Driver motor strength
c Propagation velocity of sound at STP, approx. 342 m/s
Cab Acoustic compliance of air in the enclosure
Cas Acoustical equivalent of Cms
Cmes The electrical capacitive equivalent of Mms
Cms The driver's mechanical compliance (reciprocal of stiffness)
D Effective diameter of driver
F3 -3 dB cutoff frequency
Fb Enclosure resonance (usually for reflex systems)
Fc System resonance (usually for sealed box systems)
Fs Driver free air resonance. This is the point at which driver impedance is maximum
l Length of wire immersed in magnetic field
Lces The electrical inductive equivalent of Cms
Le Driver inductance (voice coil, mainly)
Levc Driver voice coil inductance
Mas Acoustical equivalent of Mms
Mms The driver's effective mechanical mass (including air load)
n0 The reference efficiency of the system
p Density of air at STP 1.18 kg/m^3 (rho)
Pa Acoustical power)
Pe Electrical power)
Q Ratio of reactance to resistance (series circuit), or resistance to reactance (parallel circuit)
Qa The system's Q at Fb, due to absorption losses
Qec The system's Q at resonance (Fc), due to electrical losses
Qes The driver's Q at resonance (Fs), due to electrical losses
Ql The system's Q at Fb, due to leakage losses
Qmc The system's Q at resonance (Fc), due to mechanical losses
Qms The driver's Q at resonance (Fs), due to mechanical losses
Qp The system's Q at Fb, due to port losses (turbulence, viscosity, etc.)
Qtc The system's Q at resonance (Fc), due to all losses
Qts The driver's Q at resonance (Fs), due to all losses
Ras Acoustical equivalent of Rms
Re Driver DC resistance (voice coil, mainly)
Revc DC resistance of the voice coil only
Res The electrical resistive equivalent of Rms
Rg Amplifier source resistance (includes leads, crossover, etc.)
Rms The driver's mechanical losses
SAF Spouse Acceptance Factor
Sd Effective piston radiating (surface) area of driver
Vab The volume of air having the same acoustic compliance as the enclosures
Vas The volume of air having the same acoustic compliance as the driver suspension: Cms
Vb Net internal volume of enclosure
Vd Maximum linear volume of displacement of the driver (product of Sd times Xmax)
Xmax Maximum peak linear excursion of driver
Z Total driver impedance

© 1998 Michael LaLena.
All rights reserved

Qts is aka the driver's Total Quality. My SAF pa sa list!

What other drivers (not as expensive) can I investigate? Visaton? pHY? The Bicones are really looking good eh? I'll try them someday. Godspeed

Visaton (B200) is good but not as linear without BSC. Phy is pricey. For very high efficient high Qts woofers try Madison Speakers (executioner and archer series). These are Made in China although designed in the US so they claim. http://madisonspeakers.netfirms.com/rawdrivers.htm

Madison stuff can be bought at www.steelsound.com

Madisound has the Audax 6" pro midrange 100db (PR170M0) down the 250Hz. Can be used with those Madison Woofers. The Supravox RTF64 series is realatively not as pricey for high end standards at least, but I think it woold need partnering woofers or active sealed subs (Eq'd).

Ebay is still a good resource IMO for some vintage types like this one:

http://cgi.ebay.com/ws/eBayISAPI.dll?Vi ... RK:MEWA:IT

Check out the cloth surrounds on this one. Looks like damage but is actually part of the design. I've seen some Isophon vintage pro stuff with the same surrounds but have dual voice coils and magnets. Kadalasan may parang katsa na nakabalot sa legs and magnet (likod ng driver).

[joe3rp]

Q Ratio of reactance to resistance (series circuit), or resistance to reactance (parallel circuit)

Qts The driver's Q at resonance (Fs), due to all losses
[/i]

Red76,

This is the book explanation ... what does it mean?

How will identical speaker (with only a difference in QTS . same open baffle, same driving tube amp) ..react to bass. low volume, hi volume....etc

Given the same suspension/surround compliance ... what will the sound be?

WHich speaker will bottom out easiers in an OB .... one with high or low.

In an exitation speaker...will increasing the magnetic strength ... result in a what QTS...higher or lower.

[ichabod]

Correction paleeze. Right quote wrong me. I'm not too literate technically to have said those.

[setup1]

How will identical speaker (with only a difference in QTS . same open baffle, same driving tube amp) ..react to bass. low volume, hi volume....etc

Just like James I don't deem myself qualified to explain what red76 posted since I don't possess enough technical background to fully understand QTS and other driver parameters. But let me give it a shot, based on what I've read in the internet a driver QTs of .7-.8 is ideal for open baffle use. If the QTs is too low bass extension suffers.

However....audio is not an exact science and although there are merits to these kinds of measurements and tests procedures, please remember that these are all done in static mode [square waves, sine waves, pink noise and etc.] These tones are so far removed from the sound of live instruments. Always keep in mind that music is about "harmony and dynamics" and no test instrument can replicate that yet....that's why
the final arbiter in choosing a component should be ones ears. So let's not get too carried away by measurement procedures and have some fun searching for good OB drivers in an empirical way.

That said, I've never heard a Supravox or Phy drivers from France which seem to have a good following in Europe. But based on the ETF 2003 report there was a huge OB there and amongst the drivers tested in that shootout that looked familiar were the Altec 755C and Pioneer PIM8. Honestly I don't know the QTS values for these speakers but to my ears they perform quite well in an OB. Here's a link to some photos [James, if I'm not mistaken some of those other drivers are Saba, Telefunken or Siemens and maybe even Philips/Norelco].
http://www.tnt-audio.com/shows/etf03_e.html

Notice they are mostly vintage drivers which are a safe bet for OB use since maybe [?] they tend to have QTS values closer to the .7-.8 theoretically ideal figure.

IMHO, Vintage Japanese drivers are underrated and can still be acquired at an affordable price at eBay, for example this Onkyo 8" co-ax:
http://cgi.ebay.com/ws/eBayISAPI.dllVie ... 03618&rd=1

These 50s-60s drivers are analogous to Canon, Nikon, Yashica and other Leica rangefinder screw mount camera and lens copies from that era. Maybe not quite to Wetzlar standards but pretty close in quality and you'll only hear or see the difference on a side by side comparison. So there are alternatives to WECO/Altec that have yet to be tapped.

Buying tip:
Aside from the obvious [torn cones, rips and etc.] one important thing an an eBay seller should provide is the DCR of the drivers. For example my 755C pair which are nominally 8 ohms read 6.7 and 6.8 ohms on a DVM. This test [although not foolproof] will show that the voice coil is intact.

Hope this helps!

JE

[ichabod]

Well said JE!

Reading beneath the same question, there are probably countless other brands of 8 inchers that may work as well in these open configuration. Which? Those who dare will surely find out. It does not hurt anyway that it sounds beautiful at a fraction of its cost!

[red76]

Joey,

I just posted the most common parameters seen in specsheets and what Qts "means". IMHO they are just a guide to narrow down on drivers etc. Trying them out is another thing altogether... I don't have the in-depth knowledge in what really goes on, especially if you add many variables like in what you posted. Better ask Prof JM to expand on this...

Most vintage drivers/woofers that were scavenged from old theaters (Klangfilm type hornloaded OB - not neccesarily $$ klangfim) or large consoles are a good bet for OB use. Most of these were either pure OB or were used in "lossy" cabs (semi aperiodic?). With the exception of those used in Altec VOTT type bassbins, which have are designed specifically for BR and/or front hornloading. Drivers designed for large basshorns won't really work that well too.

The Madison Woofers l posted is based on the experience of one diy'r (Mats Gunnars) trying them out in his OB's along with Supravox 8". He got excellent results based on his report. Here's the pic:

http://groups.msn.com/Fudalensfabodar/s ... &PhotoID=1

Just to add to setup1's tips.. Always read the fine print. Those sellers who actually measure the vintage drivers they sell are most likely reliable. A nominal of 4 Ohms is not bad per se so don't be deterred, since most specs in days of yore are much more honest. The nominal rating is always almost near the DCR for these drivers (ie. 4 ohms usually measures 3.2), and most are benign w/in its freq. range (German types commonly use 6 or 4 ohm).

[red76]

ichabod:

Reading beneath the same question, there are probably countless other brands of 8 inchers that may work as well in these open configuration. Which?

On the Japanese front, some of these look "attractive" and OB compatible:

http://www5b.biglobe.ne.jp/~tritium/newpage1.htm

[ichabod]

After looking at the above, just ignore Japanese being Greek, some of these drivers like the pioneer PJ 8 sure looks like an altec or a saba, a tele, and what have you. Probably they were made in the hundreds of thousands and are just out there waiting to be used again.

So there's really a wide variety of these vintage types speakers to choose from, are less costly to build and a surprisingly room friendly (even in smallish rooms) than most modern box speakers. Thanks for the sites.

[setup1]

Joey,
With the exception of those used in Altec VOTT type bassbins, which have are designed specifically for BR and/or front hornloading. Drivers designed for large basshorns won't really work that well too.

This is where science can potentially hamper ones musical enjoyment and empirical thinking open a new window to musical satisfaction. Ding has been using Altec 604-8Gs on OBs since '97. He was the first person in SETUP to try the OB plan from Stereo Sound. I faxed it to him and heard the results a couple weeks ahead since I was busy with music and already had a smaller OB. Joel and Nonong followed by middle of the year when they got their 755s.

The 604 is basically a 515 woofer with a 1.5Khz horn/802 driver combo mounted coaxially and it works great on the OB. Herb Reichert heard his set up around the time Listener mag went under and was impressed. According to Ding, Herb is now using 604/OB. Likewise Joel has a 414/511/902 combo in an OB with great results. The 414, 515 and 803 were the Altec drivers used in various Altec cabs from the A5/7 front loaded horn/BR [825/828] to the 612, 614, 620 and etc. BRs. Sure they go a bit deeper in a cabinet than an OB but the amount of bass extension lost over the midrange purity gained from an OB is a subjective compromise that should be left to ones ears to decide what gives greater musical satisfaction. I've listened to several types of drivers in an OB and the only one that I felt didn't work was a Lowther PM7C.

JE

[setup1]

Well said JE!
Reading beneath the same question, there are probably countless other brands of 8 inchers that may work as well in these open configuration. Which? Those who dare will surely find out. It does not hurt anyway that it sounds beautiful at a fraction of its cost!

Hi James,

I just found out that the same Onkyo seller sold a pair of 755Es for less than $400/pr. quite a reasonable price.

http://cgi.ebay.com/ws/eBayISAPI.dll?Vi ... 08766&rd=1

IMHO, in well developed markets like here or Japan one stands to gain or loose a lot less in their investment on vintage gear over buying brand new high-end gear. Its just a question of cultivating the demand back home. I think it's just a matter of time before Robb report feature articles on vintage audio gear as they do with classic cars, cameras and time pieces, but by then they will be out of reach for most people. So adventurous people in this forum should start now....

JE

[red76]

Joey,
With the exception of those used in Altec VOTT type bassbins, which have are designed specifically for BR and/or front hornloading. Drivers designed for large basshorns won't really work that well too.

This is where science can potentially hamper ones musical enjoyment and empirical thinking open a new window to musical satisfaction. Ding has been using Altec 604-8Gs on OBs since '97. He was the first person in SETUP to try the OB plan from Stereo Sound. I faxed it to him and heard the results a couple weeks ahead since I was busy with music and already had a smaller OB. Joel and Nonong followed by middle of the year when they got their 755s.

The 604 is basically a 515 woofer with a 1.5Khz horn/802 driver combo mounted coaxially and it works great on the OB. Herb Reichert heard his set up around the time Listener mag went under and was impressed. According to Ding, Herb is now using 604/OB. Likewise Joel has a 414/511/902 combo in an OB with great results. The 414, 515 and 803 were the Altec drivers used in various Altec cabs from the A5/7 front loaded horn/BR [825/828] to the 612, 614, 620 and etc. BRs. Sure they go a bit deeper in a cabinet than an OB but the amount of bass extension lost over the midrange purity gained from an OB is a subjective compromise that should be left to ones ears to decide what gives greater musical satisfaction. I've listened to several types of drivers in an OB and the only one that I felt didn't work was a Lowther PM7C.

JE

Please Dont get me wrong... Perhaps I should have been more specific in what I've posted above, what I had in mind with my earlier post is when one would want to augment an 8 or 6" FR driver in an OB with a woofer/s. I'm NOT questioning it's validity that they would not sound good in OB. Basically what I was implying is that don't expect similar bass punch when they are mounted mounted in OB (515's etc.). Of course WRT "tonal purity" up to the lower mids it's definitely no slacker (no boxy colourations etc.) as evidenced by the Setup Gang's OB pragmatic experiments almost a decade now. You may look at it this way, some woofers may not work as well in the BASS department if you compare them side by side to let's say vintage Siemens Klangfilm stuff (like the ones featured in the previous CES). Of course this is only my opinion...

Pics coutesy of Klangfilm Home



Anyways, if it came off as a sweeping general statement, I'm amending it right now. I for one am not "rigid" (sometimes one needs to be tho ), or stick to preconceived notions on what should or should not work.

Lowthers need heavy Eq'ing to work well in OB (some even in the digital domain), but that can be a band aid of sorts depending on who you ask... Wrong way to go if you ask me.

BTW, the Corals I have don't have that high a Qts (< or = 0.5), but they definitely have "tone" and natural midbass without the piercing nasality in a crappy mockup OB made of box carton panels.

[setup1]

Hi red76,

It's cool....no offense taken at all......the only reason I quoted your post and wanted to clarify the matter is because there are many people in this forum who are now OB users as well as those who are considering this route that might be prevented from trying it if they get bogged down by QTs and other driver parameters. Please don't let this deter you from trying the OB. There is more room for error in designing a cabinet for a driver than to make the same driver work in an OB.

Some people may find that an 8" on an OB does not have enough bass for their musical pleasure so a 10-15" co-ax may fit the bill. IME a 604/OB has more qualitative bass than a typical 2-way BR or sealed type enclosure with an 8-10" woofer. Look into Altec duplex series [601, 603, 605 and 604s], EV 12/15trxs or their Japanese counterparts like what red76 has as possible candidates.

Here's a link to the recent month Joelist archives wherein there was a discussion of the Altec 755C and 601C for OB use that may further demystify the QTs question.
http://mailman.io.com/pipermail/sound/2 ... hread.html

I forgot to mention in my previous post that before this OB forum was even created I noticed a picture of 604-Hs on familiar looking but deluxe OBs in Mang Johnny's room during last November's WS show.

BTW, nice Klangfilm pics, the German answer to WE theatre gear.

JE

[joe3rp]

setup 1,

Have you used series resistance in your OB design 1- 8 ohms to adjust the Qts. In my latest experience I added a series resistor in my VOIGHT-fostex 208sigma (NOT OB ....) and it improved the mid-bass. with my 300B amp the mid-bass was lacking ...with the series resistor the low bass appeared... I already have very low bass - as per MICKEY HART planet drum demo..

Maybe with the new - hi-damping solid state amp ... too much control of the driver makes OB speaker enclosure not a good match. Now with SET triodes with low damping - relatively high output impedance ...OB is a better match

Am I getting the correct idea?

Is the KLANGFILM front horn loaded still considered open baffle?

Thank

Joe