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EV Interface B Series II

HiFi in WYO

HiFi in WYO

The universe is a big place, perhaps the biggest.
Picked up a pair of EV Interface Series II B speakers with a bundle of other goodies a couple weeks ago. They were leftover at a sale and the owner didn't want them anymore. So my price: free.

The usual dirt, grime and cracked surrounds came with them. The foam around the tweeter is also dissolving. The grills are in good shape. Had to hook them up anyhow and see what I was working with. Surprisingly, they sounded respectable even with the bad surrounds. A level knob was really scratchy so I removed one of the midranges to clean it and the foam disintegrated in my hands. Off to Simply Speakers web site for new surrounds.

Well the surrounds came in and though they weren't exact fits, they're very close. The passive woofers were mounted underneath, I decided to mount them on top which created a bit of an excess of foam. Anyhow, they're done and last night was the test run. And though I seem to say "wow" to a lot of my speaker finds, the EVs rank right up there with the best I've heard.

Crisp highs, very listenable bass. I don't really notice any mud coming through at all. No tin, no brightness, just all-around enjoyable sounds coming from these heavy monsters. I was running XM satellite jazz channel through my Fisher RS-1060 receiver. All settings flat.

Obviously, I'll play with them more – perhaps when the less audio-enthusiastic amongst my household aren't home I can turn them up a bit and see what this passive woofer really adds. But my initial impression is if you find a pair, grab them. This is the third set of EV speakers I've owned (EV Fours in the dining room, and while I was a DJ I had a pair of big EV wood cab two-ways). EV speakers have always appealed to me and I've always been impressed. If you find a pair, buy them. They're sure to surprise you!

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Nope. I still have the guy's number so I'll check. But I did get to turn up Caravanseri by Santana and they do sound great. If that eq brings more to the table, I need to find one. But research on AK seems to say this may be a hard thing to find. Even without, these are keepers.
Once again, the speaker stable is way too full :)
 
The engineers at EV were not fooling around ! They got it right most of the time.

I have to agree that these are impressive for a 8", super tweeter and a passive.
The EQ brings a little to the table but it's not night and day.

Nice grab
 
I am noticing a bit of brightness at higher volume but it's not obnoxious. And that passive really starts moving too. I wouldn't say there's any mud on the bottom end, instead, it's more of a substantial bass footprint.

And yes, I think those engineers weren't fooling around. In a way I'm glad these aren't well known. I imagine if they said JBL they wouldn't have been so cheap!
 
I grew up listening to Interface A's. I was, and still am, amazed they never really caught on, I always figured it was because they weren't subdued enough to please the east coast sound lovers, nor brash enough to excite the west coast camp. Being from Michigan, we had a house full of interface speakers. As small as they are, they'll rattle the windows on 1812 overture cannon shots. Truly great speakers!
 
The Interface Series was designed by Don Keele Jr. in about 1975. This was in the time period when Thiele/Small design methods were hitting the world big time. A normal ported box system mathematically is a 4th order polynomial: S^4/(S^4 + A*S^3 + B*S^3 + C*S^2 + D). A, B, C and D are coefficients that have the woofer and box parameters (mass, compliance, BL, Re, box volume, box tuning, etc.) mixed in them. For a high pass Butterworth alignment A, B, C and D have specific numerical values. In order to get the low end response that he wanted, Keele used a 6th order alignment. This would have six coefficients. He split the big equation into a 4th order part and a 2nd order part. The 4th order part is a physical ported speaker (in this case with a passive radiator instead of a port) along with a 2nd order electronic high pass filter in a box what works like an equilizer. The differences with and without the equilizer would show up right around F3. With the 6th order system working correctly F3 would go a little lower but the response would drop off at 18 dB/oct instead of 12 dB/oct. A passive radiator was used because the box design required a port that was physically too big for the box. The PR really only provides output right around F3. I don't know for sure but the equilizer box may also have a subsonic filter (way below F3) built in to prevent the PR from damaging itself from things like record warp.

I forgot to mention, the response curve of the "box" portion of the system is not necessarily flat. It is the sum of the box and equilizer portions that equals flat.
 
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EV is one of my favorite vintage bookshelf company! The Interface series was all good in my book especially the "C II's" As was nebtioned already they work even better with it's matched EQ in the circuit.
I think ya done good!
DC
 
Thanks!

And John, it may take me awhile to digest what you wrote. There's a reason I was a poly sci major :)
 
HiFi in WYO said:
Thanks!

And John, it may take me awhile to digest what you wrote. There's a reason I was a poly sci major :)
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I made it too complicated. I am basically trying to explain why the "equalizer" box is not just an add-on to make the response go lower. "The speaker" is an intertwined system consisting of two parts. The speaker will work without the box but EV did not provide any response curves for the box alone because it wasn't intended to be used that way.
 
I have a set of Interface A Series 1s (with the Peerless cone tweeters) - really have not spent any time listening to them. I did find it rather unique that, due to the shallowness of the cabinets, the passive spider is simply glued to the back of the box.
 
jlovda said:
I made it too complicated. I am basically trying to explain why the "equalizer" box is not just an add-on to make the response go lower. "The speaker" is an intertwined system consisting of two parts. The speaker will work without the box but EV did not provide any response curves for the box alone because it wasn't intended to be used that way.
Click to expand...

No worries. I get it. I did have to read it a few times though.
Update: No EQ to be found. So, I'll keep an eye out on d'bay and we'll see what happens.
Interestingly, I have them in the mancave paired with the Yammaha A S-500. Now I do want to hear what the eq brings. They're a lot brighter with this amp, even with the high frequency knob adjusted. The Timeframe 400s love this amp as did my 105.1s, but it's not a great fit with the EVs. I may take them back to the garage - the big Fisher pairs up nicely with them.
 
EQ boxes show up on ebay every now and then. I've got a set of Interface C and they're really nice. The foam surrounding the tweeter degraded and I replaced it with wool.

EDIT: Not wool.... wool felt. That's what I used.
 
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Wool? Hmmm. That's an idea. I see you can by new foam pads - saw them somewhere online.
 
I picked a pair of these in a trade for some Mission 737r that needed a bit of work and I wasn't using or up to the task to get to it, and they came with the EQ so I guess I got lucky! Planning to pair them with a Technics SA 5270 as soon as I get around deoxing it. Hope that 35w per channel does it, but if not I got an Onkyo M501 that can take it to 70 wpc.
 
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