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Another Electro Voice Interface D/Sentry VI thread.

Greetings from Electro Voice country. Very informative thread indeed.
Just wanted to point out that the studio version of the Interface D's (Delta's) were Sentry VI's.

Sentry IV's were another animal altogether and a great system as well. image.jpg
 
fishondwan said:
Greetings from Electro Voice country. Very informative thread indeed.
Just wanted to point out that the studio version of the Interface D's (Delta's) were Sentry VI's.

Sentry IV's were another animal altogether and a great system as well.
Click to expand...
Yes indeed, you are 100% right, correct type should be Sentry VI, my fault.
I'm always having problem with changing "IV" with "VI" and vice versa :)
 
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As a diehard EV fanatic it's wonderful to see others who've discovered just how great EV can be. I and other audio engineers generally agree that EV didn't bother with the same effort that Altec and JBL did attempting to sell to the general home consumer market because they did much better in the professional audio market where products sell themselves based purely upon performance. Of course the products EV did market to high-end consumers were as good as anything else made at the time. I'd love to have a pair of big Patricians to add to my collection some day.
 
elektroboy said:
Naturally I can't be 100% sure what would cause the louder VMR playing in 1/2 space position.
But the first thing I would do is to check the wires.
As I've mentioned, there's too many flops and imperfections in the original factory assembling of EV Deltas. Different capacitors, drivers from different production batches to mention a few.
Therefore I would not be surprised if there are wires connected wrongly to the "1/2-1/4" switch. Or maybe someone made some servicing earlier and connected wires incorrectly. Worth to check.
Secondly you should also check both VMR "L-Pad" resistors.
40ohm/20W resistor, connected parallel and 5ohm/30W connected in serie to the VMR. These are active once 1/2 switch space is activated.
For example if that 40ohm one is burned (has infinity resistance) or 5ohm is shorted (least expectable), in any of those cases VMR would play louder few dB in 1/2 setting.
Once resistors are OK, only wrong connection of the wiores/switch could be reason for VMR playing louder in 1/2space setting. As simple as this.

With regard the sound on my Deltas.
After all "step by step" changes I've done in the last 2 months (matched PIO capacitors implementation, tweeter's L-pad resistors replacement / fine tuming),
elimination of the switches (shortened signal path), tweeter's protection unit and high tones attenuator removal, my Deltas sounds fantastic. Certainly more than one class better that before these changes.
Very hearable, enjoyable, simply significant improvement. Sound is crystal clear (except occasional resonances from one VMR when playing loud - described earlier), very musical, controlled, perfectly ballanced, extremely fast and dynamic. Like sound holography.
And these mids coming from them are second to none!
Possibly the best "all round" of all speakers I've ever heard. I'm not using the equaliser. Sound of Deltas with both ports open is clearly the one i consider as the best and most natural.
Click to expand...
Thanks for answering so fast.
I plan to check the speaker on the possible issues as soon as I have to to do so. Yesterday I measured the VMRs and the tweeters on their loudness in the different positions of th switch. Here i have compared them to the loudness of the speaker without issues, the switch on 1/2.

So if the switch of the "Problem" speaker is on 1/4 the tweeter is exactly as loud as the other. But the VMR plays 6db less loud. If the switch is on 1/2 the tweeter is 2-3 db too loud and the VMR is still playing 3 db less loud.

Since i am not as experienced with speakers electronics I'd like to ask where the "L-Pad" o the VMR is?
I guess it is on the plate with the crossover but i'm not 100% sure.
 
Khaefeli said:
Thanks for answering so fast.
I plan to check the speaker on the possible issues as soon as I have to to do so. Yesterday I measured the VMRs and the tweeters on their loudness in the different positions of th switch. Here i have compared them to the loudness of the speaker without issues, the switch on 1/2.

So if the switch of the "Problem" speaker is on 1/4 the tweeter is exactly as loud as the other. But the VMR plays 6db less loud. If the switch is on 1/2 the tweeter is 2-3 db too loud and the VMR is still playing 3 db less loud.

Since i am not as experienced with speakers electronics I'd like to ask where the "L-Pad" o the VMR is?
I guess it is on the plate with the crossover but i'm not 100% sure.
Click to expand...
L-Pad is terminus technicus for the constant impedance attenuation circuit consisting of 2 resistors.
One is connected parallel and second one in serie with attenuated speaker.
Main goal why two resistors are used is to keep final impedance the same or at least simillar as it is without attenuation.
L-Pad is simply securing that crossover network will see the same impedance of the speaker (= can be working as intended) after attenuation is done.
You can certainly find more detailed explanation on the net. For example there are also online calculators to find proper values of these resistors. One of them is here >>>
In case of EV Deltas, two of such a L-pads are used. One for VMR (=resistors 5 and 40 ohm in the scheme) and second for the ST350 tweeter (resistors 2,7 and 18ohm). Both of them are activated only when 1/2 space switch is on.
I'd also recommend you to print the schematics and try to understand how these resistors and generally elements are working different switches positions.
Then it should be much easier to understand all details of this thread, but mainly to find the place where any problem could happen.
 
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elektroboy said:
L-Pad is terminus technicus for the constant impedance attenuation circuit consisting of 2 resistors.
One is connected parallel and second one in serie with attenuated speaker.
Main goal why two resistors are used is to keep final impedance the same or at least simillar as it is without attenuation.
L-Pad is simply securing that crossover network will see the same impedance of the speaker (= can be working as intended) after attenuation is done.
You can certainly find more detailed explanation on the net. For example there are also online calculators to find proper values of these resistors. One of them is here >>>
In case of EV Deltas, two of such a L-pads are used. One for VMR (=resistors 5 and 40 ohm in the scheme) and second for the ST350 tweeter (resistors 2,7 and 18ohm). Both of them are activated only when 1/2 space switch is on.
I'd also recommend you to print the schematics and try to understand how these resistors and generally elements are working different switches positions.
Then it should be much easier to understand all details of this thread, but mainly to find the place where any problem could happen.
Click to expand...

Thanks for the explanation. I finally got down to check the wires. And you were absolutly right. The wires to the 1/4 and 1/2 switch are connected differntly in both speakers. This would explain why it plays louder on 1/2. But I am still trying to figure out why one vmr is always playing less loud as the one in the other speaker. I checked the resistors and to me they seemed alrigt(was no sign of physical damage). I will open them both soon and check if the rest is also wired the excact same.
 
Ok now I've got a problem.
I just finished with checking the cables. I didn't changed anything and tried not to touch much. But now the speaker is damaged. On little loudness everything is good. But as soon as im listening a bit louder the tweeter sounds scratchy and sometimes the amplifier just stops or the volume of the high frequencys are just going up and down.
I've tested if it is the amplifier but it is the speaker.

Do you know what causes this?
 
After a pause i could play 20 seconds on a higher volume but after those seconds the tweeter again begun to scratch.
 
Check the wires and the switches, I thing you have a short circuit in the switch section.
Preferably get the switch out of the circuit
 
I still love my Interface "Epsilon" as I call my modified "D" ....
If I can get a spare woofers somewhere I will buy them without hesitation, just to be sure I can increase the life of these already senior aged workhorses.
I am listening a lot to vinyl since 30 years and have discovered how good HiFi was before CD.

And I will probably offend the true audio fanatics here but these beast do very very well in a movie Surround (Atmos) setting.

It is good to see new fans here, welcome Electroboy and good to see these units pop up again.
 
I forgot to mention that I tested the speaker on frequencies. Also with 10000hz. could it be possible that this damaged the tweeter?
 
10000 Hz with a bit volume, as loud as you would try 400 or 50 hz will kill this tweeter instantaneously as it is only 5W.
Swap the tweeter beteen left and right and check if the fault follows the tweeter.
If not run direct cables from VMR and Tweeter to the filter board and remove the junk that was in there (wiring)
 
no just remove the screws with care, remove the tweeters and unplug the faston connectors on the ST350b, or just take the wires out of a ST350a.
Make sure you put + on + en - on -.
(for testing this isn't important)
 
Ok thanks.
So I guess, since I dont have no soldering appliance I am going to buy one or let the speaker be repaired proffessionally.
 
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