[smccull]

I have a pair of Supravox 215-2000 EXCs that I'm ready to put on a baffle and see how they sound. Can't wait, since I've read so many positive things and they've been sitting in the box for months because of my move to England.

Anyway, I want to run them with my 12V Optima Yellow Top battery, but want to be able to attenuate the voltage downward because I understand they can sound quite different, and perhaps better, at lower voltages. I also use the Optima to power an Altmann DAC. This is probably a very simple question so pardon the newby.

Do I simply need to buy a linear potentiometer and put it in a box and run it from the battery through the potentiometer before the drivers? Would this allow me to bring the voltage down and measure it with a voltmeter on the other side? If so, what specs should I look for in the potentiometer? Should I wire the drivers in parallel or series?

If this doesn't work, what grade power AC/DC power supply should I be looking for? I've seen several on ebay that go from 0-30V and up to 2amps. Would two of these be sufficient?

Thanks for the help!

BTW, I'll start with just the Supravox's on the baffle to get started, but will probably end up with a three way configuration. A ribbon tweeter (Fountek?) for sparkle "crossed" with a simple capacitor, and a 12-15" woofer on the bottom running through a Behringer Ultracurve and a SS amp. Thoughts and suggestions on this configuration appreciated as well.

Cheers,

Steve

[nullspace]

Hi Steve,

Buying DC power supplies off of eBay is probably easier, but I preferred using a 12V SLA battery for my Fertin FC drivers. With them, the battery was a no-brainer as 12V was a good voltage level. For the Supravox, I think there's a bit more work involved...

First, any idea what the resistance readings are for your fieldcoils? It would be nice to know so you can fully map out voltage and current.

I'd recommend hooking the field coils up in parallel across the battery.

Second, I suppose pots might be fine but I wouldn't go that way. I'd rather have a voltage divider with big, honkin' 50W resistors. You'll have to buy several to have an 'adustable' output, but that would be my preference. And, I'd suggest you fuse both the '+' and '-' lines.

I hope that helps get you started.

Regards,
John

[smccull]

Thanks John,

I'll probably just go with something off eBay in the short term, like you suggested. Will I need two, one for each driver, or will one do if it can handle the current load?

[nullspace]

Anytime Steve.

One would be fine as long as it has a sufficient current rating. Here, I=V/R is your friend. I don't think there's any chance you'll be running more than 10-12V, measure the field coils for DCR, and then you'll have your answer about how big a supply you'll need for each driver. Of course, you'll have to double it for two drivers.

Regards,
John

[David Weil]

On the Supravox homepage 10-14 V and 5 A is recommended. Click

Potentiometers for that amount of power are available. They are big and ugly and they dissipate a lot of heat. You might rather look for 12 V SMPS designed for industrial automation. They often come with the possibility to adjust the nominal output by ± 10 to 15 %.

[levinsje]

Hi,
I have the Supravox 215-Exc field coil drivers in open baffle and use 7.5 volts.
My brother uses them in a big fun horn with a voltage of 6 volts I believe.

Jim

[smccull]

Thanks everyone for the help.

Jim, do you have the high excursion, OB version or the standard version? What size is the baffle? Did you experiment with baffle size?

[levinsje]

Steve,
My drivers are the standard, not the open baffle version.  The sound difference is small.
Initially I tried the Supravox TQWT enclosure with very good results. The bass went down to 40Hz.
My baffle is relatively small but with a 3/4" round over on the inside.
Picts are located on the Hawthorne site at the web address below:
Look on page two.
http://www.hawthorneaudio.com/forums/viewtopic.php?f=2&t=1489&st=0&sk=t&sd=a&hilit=supravox&start=15


Jim

[PaulFolbrecht]

SMC,

Still running your SV drivers, by any chance?

I had a pair a year ago and decided to pick up another pair.  For me, best sound was given on the wide, shallow "JE Labs"-type baffles - just the 8" Supravox alone, no help.  Excellent bass down to 50 Hz or so, the rest of the spectrum very balanced.

I liked them at about 6V.  They are not as sensitive at this voltage but they are not tipped-up, either, as they are at higher voltages.

[smccull]

Paul,

Actually I haven't run them at all. I've moved to England this year and had a new baby so it's been a busy year. I just pulled them out of the box last week and plan to construct some baffles soon, so your reply is very timely. What size are your baffles? Are you doing anything to augment bass? Subwoofer, additional woofers on the baffle? And what about HF? I've heard some good reports from incorporating a ribbon tweeter for that last bit of extension.

I'm looking forward to getting started on this project in earnest, so I really appreciate your experience.

Steve

[PaulFolbrecht]

Steve,

My baffles are the "JE Labs" baffles - google that and you'll find it quickly, with plans, history, etc.  Basically, they are wide and squat, with small wings, and put the driver quite low to the floor for bass reinforcement, and tilt back 10d.  They seem to work extremely well for many wideband drivers that have a low resonance frequency.

Last time I ran then I ran them plain.  I do not find a need for a super tweeter with the Supravox 215-2000, even though I know they start rolling off around 15K or so.

They were light on the low-end yet not unacceptably so, and for the acoustic jazz I listen to most, I felt no great need for subs.  However, I have ordered a pair of the TBI Magellan subs, which are supposed to be the fastest in the world, and mate very well with extremely fast drivers where essentially all 'traditional' subwoofers will not.

I think putting a woofer on the baffle would not be a great idea, as unless it was extremely heavy & rigid vibration would blur the mids, and furthermore it just really isn't necessary.  The 8" SV driver alone will give you solid bass to 50 Hz or nearly so.

All this stuff is on its way and I may be able to report back in a few weeks.  I am also busy with a new baby, born Saturday, 13 weeks premature - so, as you can understand, audio is far from a priority of mine right now!  We are pulling for our tiny one who is doing well so far but does certainly face challenges.

[smccull]

Paul,

I finally got around to hooking up one of the SVs with no baffle, just to begin the process of getting everything hooked up and to see what it might sound like. Very promising just from what I could hear on one driver off the baffle. I have a variable DC power supply so I was able to ease up the voltage slowly on the driver. I went up to 6V to see what that sounded like and I could tell that it was sounding a bit richer and fuller, but I seemed to be getting a hum through the driver as I ramped up the voltage. I'm wondering if you have any ideas on what could cause that. Could it be a bad power supply, which I bought off eBay, or perhaps a loose connection somewhere? I just used some cheap lamp wire to run the connection before I can get to the hardware store to pick up some supplies, and i didn't bother to put on a proper termination to connect to the power supply. Any thoughts you might have would be very helpful.

I think I'm going to set up the JE Labs baffle as a start because I read about some of the success folks have had with this simple design. It should be a good way to see what these things will do in a full stereo setup.

Steve

[PaulFolbrecht]

Steve,

I never experienced any hum.  I can't see the wire making any difference in that regard.  Certainly, no shielding is necessary given the low voltage!

Hmm - that is a stumped.  You might try contacting the importer.

[PaulFolbrecht]

Steve, any progress on your problem?

My drivers should finally be here late this week.

[smccull]

I haven't been able to get rid of the hum yet, but I haven't tried very hard. I think it might be my power supply. It's a used one I bought off ebay and it may be a dud.

I have, however, built the JE Labs baffles and they sound quite good. My room is a bit narrow, so I don't get the widest soundstage but they sound really, really smooth and balanced. A little rolled off on the top, and bottom especially, but overall a good start. I went ahead and splurged on baltic birch so there's a good chance they'll be my permanent solution for a while. I would like to add a couple subs in the corners behind, and maybe some ribbon tweeters to add that last little bit of sparkle.

Let me know how you like yours when they arrive. Cheers.

Steve

[PaulFolbrecht]

Steve,

Timely reply, as I just checked the thread today - and my drivers are on the way from Canada.

(I already had the JE Labs baffles I build the last time I had these drivers.)

Certainly, they are a bit rolled, but it did not bother me much at all - especially on top.  They are down only 3 dB at 17 Khz or so which is damn good.

I chap named XCortes who posts on AA mailed me his in-room measurements of his JE Labs/Supravox 215-2000 setup, and the response was *incredibly* flat - like +- 3 dB from 45-12 Khz.

I was getting very good bass to 50 Hz in my room last time.  For the acoustic jazz I listen to most of the time, that's just fine.  I have, however, procured a pair of TBI Magellan powered subs and have high hopes for them.

By next weekend I should have it all together.

[Telstar]

(I already had the JE Labs baffles I build the last time I had these drivers.)

Can you post a link to these baffles?

[PaulFolbrecht]

If you google 'JE Labs open baffle' it's the first hit:

http://members.myactv.net/~je2a3/open.htm