Another Electro Voice Interface D/Sentry VI thread.

[turnitdown]

The STs sound great...

but when I reigned in the VMR to match the ST it was magic and I matched them with the CV 12" from a a set of D-5s because the sensitivity was right there where it needed to be. I am LOVING these. Thanks for the inspiration everyone.

 

[PeterSchut]

So the Type C and D speakers used the same resistor network?

yes, but the C is a very different animal in all respects. The 2" VC VMR is not as powerful and the dynamics of the big woofer, big VMR and ST350 are awesome without any competition.

 

[PeterSchut]

An update with simulations and woofer TS values

Hi Forum
I have received the Dayton DATS device and measured the TS parameters of some drivers.
The woofers are very equal and have some interesting parameters.
If I put these parameters in WinISD the curves are not very nice until I put the 2.5 Ohm in series with the woofer. This 2.5 ohm resistor has been puzzling me for a while but here is the "theoretical" explanation
There are two pictures of these graphs. One set has a 0.1 Ohm in series with the woofer, the other has a 2.5 Ohm resistor in series with the woofer.
All plots are made with a source of 2.83V (2W) in a 111 Liter enclosure.
In the white plot in both graphs the enclosure is tuned at 41Hz
In the yellow plot in both graphs the enclosure is tuned at 31Hz
In the red plot in both graphs the enclosure is also tuned at 31Hz but with a 6dB boost at 31Hz (the Interface D EQ)

I think that these theoretical plots are unbelievable and ideal to what originally has been designed.
The 2.5 Ohm in series is very much needed to smooth the response.... incredible.
But why do none of my measurements show these results? (i need to check my mic I guess)

 

[PeterSchut]

But then there re VMR's (TS parameters)

But then... VMR's
I have measured the Interface D VMR's called VMR L and VMR R.
The VMR R has a much higher resonance frequency and I couldn't measure VAS by adding a mass to the cone.
Really disappointing. The VMR L has a really low FS ....
The VMR 1 and 2 are the pro versions. Although different they are similar.

I guess I need to move to two Pro VMR's for the fronts and adapt them to the filter or try to get an Interface D VMR ....

The frequency curves are in a document I posted a few posts back.

Have fun.....

 

[totem]

Interesting reading, keep the data coming.

 

[PeterSchut]

another update; things are going to make sense

Hi guys,

I am measuring the TS parameters of the different VMR's. and that is a dificult task as they interact with the enclosure in a strange way.
More to follow later.

I also performed some near field woofer measurements.
The plots below are measured with the Interface D on its back on a table. The base plate removed and the microphone very close to the woofer and in front (also very close) to the port. One measurement with one port closed (the 30Hz tuning) and one measurement with both ports open (the 44Hz tuning)

The close microphone measurement is used to remove the influence of the room.

One frequency plot is the woofer by itself the other plot is with the filter in front of the woofer.

I can only add: textbook results as mentioned in the EV documentation.

 

[Dr. Mordo]

As far as I can tell the images are identical - did you accidentally upload the same image twice?

What's there is pretty interesting, though!

 

[PeterSchut]

As far as I can tell the images are identical - did you accidentally upload the same image twice?

What's there is pretty interesting, though!

you're right, not sure what happened, but it should be ok now.

 

[Dr. Mordo]

Interesting. You can certainly see why they crossed over the woofer where they did!

 

[PeterSchut]

The VMR's reveiled

So another good day in measuring and making progress.

First a note why there was so much confusion about the LF measurements.
If I plug a mini jack into my laptop it asks if this is a mic or a line source....
Mic of course ..... wrong .... the mic input has quite a steep Hi-Pass filter to avoid contact sound from skype head sets. Choose line and you are fine even the levels are ok.
Yesterday i plugged the mic into the jack input and did not notice the popup that defaults in "line" ..... so all LF measurements in this thread from before yesterday lack bass because of this.

A nice guy I know in the Netherlands that is an official EV recone specialist had two old but nice looking VMR's. I bought them to complete my setup for 5 speakers (one spare).
I was also investigating the possibility of reconing one. It happens that most Pro VMR's are difficult to take apart. The Interface D VMR (in my plots called VMR- L or VMR-R) can be taken apart by loosening the 3 bolts in the bottom and the magnet assembly and what is left can be seen on attached picture.
Pro VMR's have a kit/glue between the metal pan and the plastic front, and sometimes they are glued to the bottom of the metal pan.

He mentioned that it is wise to coat the surround of the VMR cloth with a special latex/rubber coating designed for foam or cloth surrounds. It smells and looks just like wood glue, but it is NOT. It dries clear.

As I had some differences in TS values between VMR L and VMR R i decided to coat the surrounds. Inspection of the units showed that one was coated the other wasn't. I did both and the TS parameters of VMR-L are now much closer to VMR-R

In attached plots you see all 6 VMR's in one graph. The graph with full range plots is made by applying the signal unfiltered so from 20Hz to 20kHz, the filter plot is where the VMR's are connected to the interface D filter. The third graph just the L-R interface D VMR's after coating.

The funny part is that the pro VMR 1-2-3-4 are a bit louder unfiltered but attached to the Interface Filter (with 5 Ohms in series and 40 Ohm parallel) they are remarkably identical, the louder lower impedance Pro VMR is damped a bit more attached to the filter.
Conclusion: you can use a pro VMR in place of the Interface VMR with little or no change to the filter. At least individually measured. How they interact with the woofer and tweeter will be tested next time.

Cheers

 

[absolve2525]

That's excellent information about being able to substitute pro VMR for Interface D models! I have a few pair of pro units, and a set of recently refurbished Interface D keep us updated!

 

[PeterSchut]

That's excellent information about being able to substitute pro VMR for Interface D models! I have a few pair of pro units, and a set of recently refurbished Interface D keep us updated!

This will be working best with the environment switch in 1/4 space (wall/floor).
In my redesign I will not use any switches (purism) but the 10kHz switch did not do it for me and the environmental switch was always in 1/4 position.

So you have an Interface D as well, or Interface D VMR's? What was refurbished?

 

[absolve2525]

I purchased a set of Interface D with grills and C/D eq box a few weeks ago from a dealer in Ohio. He said they came from the estate of someone in the radio broadcasting industry. He had an offer from someone planning to ship them to Italy, but I was within driving distance and we worked something out. The veneers are gorgeous, just like the Interface C that I owned. I barely had to touch the wood finish. I did, however, have to repaint the bases in flat black. They really turned out nice. I also refoamed the woofers and replaced the electrolytic in the crossovers. I also unscrewed and pulled off the second bass port underneath, as recommend by Hunter. I bought a recapped Interface B/C eq from a member on here, and have been using that since it appears to have the same attenuation. I like the EV eq boxes. I have some EV pro speakers that use the VMRs, for home use.

 

[PeterSchut]

I purchased a set of Interface D with grills and C/D eq box a few weeks ago from a dealer in Ohio. He said they came from the estate of someone in the radio broadcasting industry. He had an offer from someone planning to ship them to Italy, but I was within driving distance and we worked something out. The veneers are gorgeous, just like the Interface C that I owned. I barely had to touch the wood finish. I did, however, have to repaint the bases in flat black. They really turned out nice. I also refoamed the woofers and replaced the electrolytic in the crossovers. I also unscrewed and pulled off the second bass port underneath, as recommend by Hunter. I bought a recapped Interface B/C eq from a member on here, and have been using that since it appears to have the same attenuation. I like the EV eq boxes. I have some EV pro speakers that use the VMRs, for home use.

Did you put some pictures in this forum? I am very interested in them and their perfect status. My cabinets need some work. I would love to get my hands on Howards Restore-A-Finish that somebody in this forum used but it is not availble here and they won't ship it to europe because of hazardous substances.
I am going to rebuilt the enclosure anyway but giving the enclosure a bit of threatment would be nice. There are a few guys in Europe who are interested in the empty enclosures so I will sell them eventually.

 

[absolve2525]

It's been a hectic past few weeks, I haven't had a chance to post photos! I will definitely take some soon.

 

[hunter00]

picks of my EV D's

heres a few pics of my ev-d's,they are what I believer to be the first original series D made

 

[absolve2525]

Very nice! Do you have them on stands? Cool binding post upgrade.

 

[hunter00]

Very nice! Do you have them on stands? Cool binding post upgrade.

Yes I have them up on a pair of custome made metal stands about 12 inchs up off the floor,and pulled back from the rear walls approx. 14 inchs.When I originally did the refoam I added the speaker binding posts as the stock ones where pretty hokey.Im glad this thread got started as there are not that many that own these great speakers so not much first hand knowledge on their performance.Ive been buying/selling/listening to various hi end speakers since my first system my parents bought me in 1975[Along with 3 albums..Alice cooper killer,Led zep houses of the holly and rolling stones let it bleed!}and ive settled on this speaker,they will be my last main system speaker,will pass them down to one of the kids.

 

[absolve2525]

I like that stand idea! I'll have to keep an eye out for something suitable. I was just playing Pharrell Williams new CD, and I'm left in awe. Punchy, tuneful, deep tight bass. I have heard quite a few setups too, and I am happy that these exceed my expectations.

 

[absolve2525]

Photos! Finally. I stored away the original grills for now. My girlfriend's kittens don't get to destroy them. Fortunately, I found these neat VMR covers on the auction site. They're perforated metal and the driver magnet keeps them secure. I couldn't notice much difference with them off or on, so I keep them on for safety. My dumb phone photos never turn out right! 1/2 Pictures, more on next page