pete_mac Posted December 27, 2012 Posted December 27, 2012 (edited) Howdy! I recently acquired a fairly clean pair of EV Interface A Series III speakers with rotten foams, but inclusive of the outboard EQ unit. Thanks to andrew7777 for the heads-up on this one! Cheer mate They have a 1.5" 'superdome' tweeter, 8" woofer, and 10" passive radiator. They are reasonably efficient (92db/1w/1m) and would work quite nicely with low-powered valve amps methinks. Replacing the foams should be straight-forward. I've done many speakers in the past, including EV Interface 1 Series II speakers which I really liked the sound of. I was careful to buy the correct 'filled fillet' woofer foams, and the correct passive radiator foams from Rick Cobb. I will purchase the foam acoustic lenses in future if I'm happy with the sound of the speakers post-restoration. The crossovers are also prime for tweaking. I'll most likely throw some polypropylene AXON caps in there to replace the originals. The caps on the woofer circuit are nasty electrolytics that always drift in value, and the polyester caps on the tweeter circuit aren't so bad, but will be replaced nonetheless. The walnut veneer cabinet is in pretty good nick and should come up nicely. The grilles need a bit of a clean but aren't too shabby I'm really looking forward to having a listen to these suckers once they are working once again. Watch this space for further updates! The Interface A Series III EDS can be viewed here: http://www.electrovoice.com/downloadfile.php?i=971387 Edited December 27, 2012 by pete_mac 1
pete_mac Posted December 28, 2012 Author Posted December 28, 2012 Two drivers down... two to go! I also found an error in the crossover - one of the polyester film caps for the tweeter circuit was soldered to the wrong tag, meaning that instead of having 10uf capacitance, there was only 5uf. Accordingly, the tweeter would have been crossed over far higher than intended. The other speaker is fine, so there would have been a noticeable mismatch between the two... and it came this way from the factory! Whoops! A nudie of the EQ unit:
pete_mac Posted December 29, 2012 Author Posted December 29, 2012 (edited) Looks good Thanks mate! A further update... all of the drivers are refoamed and reinstalled! I was going to throw some new capacitors into the crossover, along with new binding posts, but I'll need to make a new crossover setup to allow this to work properly due to space constraints and the design of the original crossover (mounted on a solder tag strip). So, for the time being, I measured the original caps (26uf caps measure about 31-32uf, and the pair of 5uf polyesters are around 10uf) and added a small polypropylene bypass cap to each (I have a large batch of cheap 0.01ufs from ApexJr for this purpose). I fired them up in the garage via a 50WPC Marantz and they sound pretty darn good in such a big space. The EQ certainly adds bass extension. Listening to Interface A to D speakers without the EQ would mean you're not getting the full Interface experience, that's for sure. The tweeter attenuation works great but I prefer it flat. You'll note how shallow the cabinets are! Next on the list is sourcing the tweeter foam lenses, cleaning the cabinets and front face, oiling the walnut venner, cleaning the grilles, and recapping the EQ. I also need to sand and respray the speaker stands - rusty much? Edited December 29, 2012 by pete_mac 3
skippy124 Posted December 29, 2012 Posted December 29, 2012 Hi Pete, They came up very well (after seeing them in bits a couple of days ago). Look forward to having a listen 1
pete_mac Posted December 29, 2012 Author Posted December 29, 2012 Hi Pete, They came up very well (after seeing them in bits a couple of days ago). Look forward to having a listen Thanks Dad. With a bit more cleaning and the foam lenses for the tweeters, they should be pretty darn good, and the future crossover upgrade will be the icing on the cake. You may have the opportunity for an extended listen in a few months depending upon how things pan out over here at Casa Del Mac
pete_mac Posted December 29, 2012 Author Posted December 29, 2012 Nice work Mac. Cheers mate! It's always nice saving a decent pair of vintage speakers from landfill.
Zaphod Beeblebrox Posted December 29, 2012 Posted December 29, 2012 As I recall, the EV Interface series were the first commercial speakers to use CAD, using Thiele/Small calculations. The computer used was reputed to cost around US$500,000.00. 10 years later, I was doing the same calculations on a $2k computer. It took around 30 minutes to run the simulatons on my 8088 processor (+co-processor). Now, the same calcs could, concievably, be done on a smart 'phone in a few seconds (I wonder if there is an app for that?). My Intel i5 does them in them blink of an eye. I probably modified your EQ for 240VAC, as I did a lot of contract work for EV Australia back in the 80s. 1
pete_mac Posted December 29, 2012 Author Posted December 29, 2012 Hi Trevor, Indeed! EV mentioned in their brochures that they were the first to use T/S calcs with this range of speakers. It's amazing how far processing power has come when you look back at examples such as the ones you provide. Funny you mention the EQ unit... Dad and I popped the lid off to have a look at what had been done to convert it for use on Australian voltages. If it was you, very neat work! I think the replacement Australian cord was branded 'CMA' from memor (Cable Makers Australia according to Dad?)
LogicprObe Posted December 29, 2012 Posted December 29, 2012 Nice work!......as usual. I remember hearing a pair of these in a studio many years ago.
pete_mac Posted December 30, 2012 Author Posted December 30, 2012 Excellent, they live again Thanks for providing me with the seller's details mate.
unclemack Posted December 30, 2012 Posted December 30, 2012 Gee Pete, I wish I had your talent for restoring this stuff. These look lovely. I'm a sucker for this type of vintage speaker. Great work mate. Cheers M.
blackangus Posted January 2, 2013 Posted January 2, 2013 Hey I have been using a set of these for the last twenty years in my main system. But your post has reminded me to hunt down the eq - I haven't used it in years. I had total recoil in Thornbury do a bit of a number on mine a couple of years ago with new tweeters and crossovers, big improvement Out of interest Pete, what height are your stands? mine did not come with the speakers, and are approx 20 cm high which strikes me as less than ideal
pete_mac Posted January 3, 2013 Author Posted January 3, 2013 Hi mate, Mine are 23cm high. I haven't yet listened to the speakers indoors as yet, so I cannot say whether these stands will place the drivers at the appropriate height when I'm seated.
pete_mac Posted January 3, 2013 Author Posted January 3, 2013 The EQ is now recapped! Nichicon HE electrolytics replace the radial electrolytics and Panasonic ECQV film caps replace the axial electrolytics. I've also included a pic of the mods undertaken back in the day (perhaps by Zaphod as he mentioned earlier in the thread!) to the power supply/transformer traces on the PCB to suit Australian voltages rather than US voltages for which the unit was originally designed. The EQ has cleaned up really nicely and the orange neon power indicator light is a nice touch. Really looking forward to having a listen to these speakers on my main system now!
andrew7777 Posted January 3, 2013 Posted January 3, 2013 Looks good! Looking forward to the listening test review
pete_mac Posted February 20, 2013 Author Posted February 20, 2013 Another piece in the puzzle... The foam acoustic lenses for the tweeters. These consist of an outer and inner foam, with the outer foam being a lightweight open-cell foam to help address diffraction issues, and the inner foam lens being much higher in density. Word has it that these have now been discontinued, so I ordered two complete sets for good measure. The speakers are currently at skippy124's due to an upcoming move, but once things settle down I will install these suckers, along with new crossover caps which will be ordered from partsconnexion shortly. Sorry for the crap iPhone pics. I will post better ones when I actually install these.
LogicprObe Posted February 20, 2013 Posted February 20, 2013 They are like the old Senny headphone pads! Where are you moving to now?
pete_mac Posted February 20, 2013 Author Posted February 20, 2013 Yep, they do look similar! We'll be renting for a while until we finish building our new house at Gledswood Hills (near Camden).
LogicprObe Posted February 20, 2013 Posted February 20, 2013 Save money!Move in with the old man for a while! Just chuck all that junk out of his shed and away you go!
pete_mac Posted February 20, 2013 Author Posted February 20, 2013 Hehe... We'd need a shipping container or a big storage room added to Dad's house first.
Guest Muon Posted February 20, 2013 Posted February 20, 2013 I have liked a couple of posts here, but need to say that ya' did a nice job on those EV's I haven't looked at the impedance curve of these, but would like to know how those would go on a valve amp.
pete_mac Posted February 20, 2013 Author Posted February 20, 2013 Thank you sir! It is my understanding that these present a fairly easy load, and being 92db sensitivity, they should do a resonable job with most valve amps methinks. I will investigate further for the sake of accuracy though. I've also found an original review on eBay which is from a hifi mag back when these speakers were first released. I'm not sure if it will have impedance curve measurements etc... Perhaps I should spend the princely sum of $10 incl delivery and find out.
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