hunter00
Super Member
very interesting peter.so just to be clear are you saying the EQ is NOT needed on the EV D that have the base ports if those ports are not installed?
Another Electro Voice Interface D/Sentry VI thread.
- Thread starter PeterSchut
- Start date
very interesting peter.so just to be clear are you saying the EQ is NOT needed on the EV D that have the base ports if those ports are not installed?
PeterSchut
Active Member
Indeed but at the expense of true LF response 40Hz instead of 28Hz
PeterSchut
Active Member
An update on the project.
Today the Interface A Eq arrived and the Interface 300 speaker.
I need to check the Eq, but I am confident that I will be fine after modification.
The bummer was that I bought the Interface 300 with the knowledge that the tweeter was soft. As I wanted the speakers to become my surround set with the dome tweeter replaced by an ST350b (that I tested last Saturday as you can read in the report a few messages back)
But.... the tweeters seem to be OK, really nice foam still on them and the whole speaker is in a nice shape. Unfortunately one VMR II is stuck. The cone won't move. They seem to be refoamed as the VMR II surround is foam (originally a cloth). By itself that would not be a problem but now one is really defect the set is useless for my plan. VMR II's are rare and I found an aftermarket recone set at Simply Speakers but I am not sure it is worth it as I need to do both.
On top of that the woofer's magnet structure looks really tiny. I would have expected that an Interface C/Gamma/300 would have a speaker comparable to the "D" but this is a toy. Unless this isn't the original woofer.
Can anybody confirm that this woofer looks original?
Well I have to reconsider my plan. I want a VMR and ST350 in the surrounds and Center channel as well. The two VMR's I have are very different and not ideal as the surround speakers, so I need to look for something else. And a real woofer, not these toys.
I'll let you know what happens. In the meantime the plan for rebuilding the Interface D is still happening and should end up as attached picture
Today the Interface A Eq arrived and the Interface 300 speaker.
I need to check the Eq, but I am confident that I will be fine after modification.
The bummer was that I bought the Interface 300 with the knowledge that the tweeter was soft. As I wanted the speakers to become my surround set with the dome tweeter replaced by an ST350b (that I tested last Saturday as you can read in the report a few messages back)
But.... the tweeters seem to be OK, really nice foam still on them and the whole speaker is in a nice shape. Unfortunately one VMR II is stuck. The cone won't move. They seem to be refoamed as the VMR II surround is foam (originally a cloth). By itself that would not be a problem but now one is really defect the set is useless for my plan. VMR II's are rare and I found an aftermarket recone set at Simply Speakers but I am not sure it is worth it as I need to do both.
On top of that the woofer's magnet structure looks really tiny. I would have expected that an Interface C/Gamma/300 would have a speaker comparable to the "D" but this is a toy. Unless this isn't the original woofer.
Can anybody confirm that this woofer looks original?
Well I have to reconsider my plan. I want a VMR and ST350 in the surrounds and Center channel as well. The two VMR's I have are very different and not ideal as the surround speakers, so I need to look for something else. And a real woofer, not these toys.
I'll let you know what happens. In the meantime the plan for rebuilding the Interface D is still happening and should end up as attached picture
Attachments
hunter00
Super Member
good luck on you EV D rebuild peter.When I first purchased mine I tore the cabinets down as had to refoam the 12 in down fireing woofer.I had a friend test values on a couple caps off the cross over boards as you would generally assume theyd dive over the passage of time but they came back within 5 % of original values.EV build on these speakers was excellent.IN relation to use without the EQ I will take your word that im not getting LF response down to 28hz but man I very happy with the low end and without someone telling you ,youd never know it! As a side note ive see lots of strange things in this hobby but when I originally picked these EV 's up they were in a delabidated building in an old area of down town Vancouver and when I got them home and started to dismantle there was someones cut-off pony tail stuffed between the base and the speaker by the woofer....full off cobb webs to boot...yuk!
totem
Addicted Member
So the D follows the Sentry III's in that the EQ is used when one of the ports is blocked off, resulting in the low end response going from 40 to 28.
That I was unaware of, I guess I should re-read the D manual.
FYI while I was looking through a 1979 Stereo Buyers guide I noticed both the D
and the III,s were listed but the following year 1980 only the D were shown.
Looks like that was the transition time line.
hunter I have always wanted to have a pair of D,s and a pair of the III's together
for a listen, perhaps we might be able to at least listen to both as we are not far from each other?
That I was unaware of, I guess I should re-read the D manual.
FYI while I was looking through a 1979 Stereo Buyers guide I noticed both the D
and the III,s were listed but the following year 1980 only the D were shown.
Looks like that was the transition time line.
hunter I have always wanted to have a pair of D,s and a pair of the III's together
for a listen, perhaps we might be able to at least listen to both as we are not far from each other?
PeterSchut
Active Member
hunter00
Super Member
Totem,sure id go for that tho im out in the valley now and I don't think either of us wants to cart these speakers around with the weights associated...I drive mine with tube amps,mostly dynaco mono block mkiv,but sometimes with a st70 as well.have used heathkit mono and eico tube amps,EV d's shine with any tube amp I find.
PeterSchut
Active Member
Filter rebuilt work in progress
Hi,
The Filter rebuilt is on its way. The poor sounding transformer core inductors are replaced by air inductors and all caps are high-end Mundorf.
The filter does not fit in the original Interface D place, but in the new design that is not needed.
It is quite a big filter (400x210mm) heavy and placed on a very sturdy hard paper (trespa) plate.
See pictures.
I hope next weekend to finish it and do some comparing listening tests.
Hi,
The Filter rebuilt is on its way. The poor sounding transformer core inductors are replaced by air inductors and all caps are high-end Mundorf.
The filter does not fit in the original Interface D place, but in the new design that is not needed.
It is quite a big filter (400x210mm) heavy and placed on a very sturdy hard paper (trespa) plate.
See pictures.
I hope next weekend to finish it and do some comparing listening tests.
Attachments
PeterSchut
Active Member
An Interface D needs an EQ
Hi guys,
I have tested the new filters (see attached picture).
This is becoming a really nice speaker and they excel in dynamics which is very addictive. I have included the Interface A EQ and .... oh my god, what a different speaker it is. Like the extra bass foundation makes the total unit sound better. Interface D owners, get yourself an EQ. The A boost 35Hz and should be 31, but still every part of the spectrum is better
I decided to not include the relay protection, and so far I have not seen any issues. (with the original filter I never saw the light come up either)
Would it be fair to say that in a HiFi application with powerful but still modest playback levels this should be OK?
Has any of you ever got the unit into protection?
I still need to measure it but maybe this protection circuit has some influence on the response.
Hi guys,
I have tested the new filters (see attached picture).
This is becoming a really nice speaker and they excel in dynamics which is very addictive. I have included the Interface A EQ and .... oh my god, what a different speaker it is. Like the extra bass foundation makes the total unit sound better. Interface D owners, get yourself an EQ. The A boost 35Hz and should be 31, but still every part of the spectrum is better
I decided to not include the relay protection, and so far I have not seen any issues. (with the original filter I never saw the light come up either)
Would it be fair to say that in a HiFi application with powerful but still modest playback levels this should be OK?
Has any of you ever got the unit into protection?
I still need to measure it but maybe this protection circuit has some influence on the response.
Attachments
PeterSchut
Active Member
Measuring the Equalizer
In the listening session it became obvious that the "0" dB setting of the Interface A Equalizer was too bright.
I wasn't sure why but I thought it had something to do with the new filter components and the removal of the protection unit.
Well, after measuring the Interface A equalizer it became obvious.
First I need to say that this lightweight simple device works like a charm and measures extremely well.
But: the 0dB position has a 3dB boost at 10k, the -3dB position has a perfect flat response (with of course the +6dB LF boost) and the -6dB position is actually a -3dB curve.
Beside the 6dB boost the gain is well within 0.1 of applied source signal and the inter channel differences is below 0.05dB.
Distortion at 1V RMS was 0.004% @1kHz
See frequency response of attached graph.
Cheers
In the listening session it became obvious that the "0" dB setting of the Interface A Equalizer was too bright.
I wasn't sure why but I thought it had something to do with the new filter components and the removal of the protection unit.
Well, after measuring the Interface A equalizer it became obvious.
First I need to say that this lightweight simple device works like a charm and measures extremely well.
But: the 0dB position has a 3dB boost at 10k, the -3dB position has a perfect flat response (with of course the +6dB LF boost) and the -6dB position is actually a -3dB curve.
Beside the 6dB boost the gain is well within 0.1 of applied source signal and the inter channel differences is below 0.05dB.
Distortion at 1V RMS was 0.004% @1kHz
See frequency response of attached graph.
Cheers
Attachments
Coytee
Super Member
(cough to distract the crowd)
Yes, I have
(cough again to keep the crowds attention elsewhere)
To boot, I had it happen while in my dorm room... listening to a dbx encoded disk of The Who's Won't get fooled again.
Yes, I've burnt a tweeter once/twice (I think twice)
First time I carted the entire speaker into my car, drove it 60 miles to a service shop, returned 3 weeks later & muscled it back home.
second time I was older and wiser.... I removed the tweeter & did it myself.
As long as you don't get stupid loud, I'd speculate you'd be fine with bypassing the circuit. Remember... I was doing this as a freshman in college so everyone in the dorm was outgunning each other.
Once I turned up Won't get Fooled Again, my room was very (very) loud but the rest of the hallway grew quiet.
Turned around and there were 15 or so faces poking their heads in my door with their mouths agape, not believing what they just heard & felt.
Yeah.... it was the day they realized their little "X" stereos just met something on steroids.
It was a good day.
:thmbsp:
PeterSchut
Active Member
Interface A/B/C/D schematic
Hi guys,
I have a schematic of the Interface A equalizer that uses 5 transistors per channel.
The unit I have and mentioned above uses 6 transistors per channel and has a different layout.
Does anybody have the 6 transistor schematic/layout service document?
Thanks
Hi guys,
I have a schematic of the Interface A equalizer that uses 5 transistors per channel.
The unit I have and mentioned above uses 6 transistors per channel and has a different layout.
Does anybody have the 6 transistor schematic/layout service document?
Thanks
hunter00
Super Member
It would be good if someone with the right abilities and knowledge here could reverse engineer these EV equilizers and produce a low cost stand in replacement.Its almost inpossible to find a 'D' eq box,i have ran ad's on canuck aud, on and off the last few yrs and nothing.I watch ebay constantly...nothing...there must be a audiokarma guru here that could take this on,id be a buyer forsure...
Dr. Mordo
Doctor of Rockology
The Interface A service manual has both the full schematic (5 transistor version) including the power supply and the circuit board layout.
It would be not too difficult to etch a circuit board using the layout in the manual, and then you just have to source the parts (replacing appropriate values for the D eq), load the board. and wire it up.
It would certainly be easier just to buy an A eq and mod it, or even easier to just buy a digital eq and set it to do what the I-D eq would do. I understand the Behringer DEQ2496 is popular for this type of application.
It would be not too difficult to etch a circuit board using the layout in the manual, and then you just have to source the parts (replacing appropriate values for the D eq), load the board. and wire it up.
It would certainly be easier just to buy an A eq and mod it, or even easier to just buy a digital eq and set it to do what the I-D eq would do. I understand the Behringer DEQ2496 is popular for this type of application.
hunter00
Super Member
hey dr.M thankx for your reply.I had a line on a b eq at one time but the owner wanted 150.00 plus shipping...So unless you could happen apon a cheap ev stock a,b eq box it hardly makes it financially fessible.A simplized version with just a power switch and wireing /rca inputs to hook up to speakers/amp would be all that's needed other than a generic box to mount it in.
Dr. Mordo
Doctor of Rockology
You should watch American ebay like a hawk. There's a function called "Follow This Search" at the top of the page. It updates you everyday if you click "Email me when new items..."
Search for "electro voice interface" without the quotes then follow the search and just wait until one pops up. I've seen three or four in the last year (no I-D eqs, though), so it's just a matter of time. They all sold for ~$50.
Or like I said, watch ebay for a Behringer DEQ2496. I'd imagine if you were patient you could get one for $150ish, but it's far more flexible than the stock eq box.
Search for "electro voice interface" without the quotes then follow the search and just wait until one pops up. I've seen three or four in the last year (no I-D eqs, though), so it's just a matter of time. They all sold for ~$50.
Or like I said, watch ebay for a Behringer DEQ2496. I'd imagine if you were patient you could get one for $150ish, but it's far more flexible than the stock eq box.
hunter00
Super Member
thx dr,i will just keep the search going.I have experimented with takeing the covers off the bass port and running them in place and have settled on leaving them open.I run dynaco tube amps and tube preamps and just top level sound.I recently added a single 1954 jbl 001 stuffed speaker{175 dhl horn and w120a 15 inch woofer}16 ohm to experiment with and other than having to adjust the balance on my preamp the 2 speakers sound surprisingly alike altho no midrange driver in the jbl.
Dr. Mordo
Doctor of Rockology
Much of that similarity will be a function of your room. Rooms amplify certain freqs and muffle others, so they can drastically change the sound of your speakers. Some of it you can fix with a room eq, but fixing the room as much as possible then tuning the rest out with an eq is preferable by far.
That's why room treatment is a very good idea for serious audio enthusiasts. One of my rooms has a terrible bump around 100hz. If I wasn't moving later this year I'd aggressively treat it.
Sorry for the thread derail.
That's why room treatment is a very good idea for serious audio enthusiasts. One of my rooms has a terrible bump around 100hz. If I wasn't moving later this year I'd aggressively treat it.
Sorry for the thread derail.
hunter00
Super Member
What are your thoughts on running the d's with the ports open undernieth without the d box?To my ears it opens up the sound reproduction ,improves detail,slightly improves bass response.When I moved last yr I had to deside between hi powered ss amps with my original AR-9 speakers or tubes and the EV d's.As you can see in my avatar the tubes and d's won by a long shot.
Dr. Mordo
Doctor of Rockology
Sadly I have never heard a set of I-Ds so I can't say what the difference would be. I am dubious about the "open the port, raise the pitch of the box" because it seems contrary to the speaker design concepts I have studied.
But looking at what Peter says above"The first mode was where the two ports are open. A bit strange at first but that increases the tuning frequency to 44Hz. With one port covered the tuning frequency lowers (at the cost of some increased port air velocity) and then the eq comes in. Port and eq are tuned at 31Hz."
So, if it works as the engineer says, the difference between "port closed w/eq" and "port open w/out eq" is the same as the difference between F1 (44hz, the lowest F on a piano) and B0 (31hz, the lowest B on a piano). Actually, the speakers will extend a bit below those numbers, because those are the pitches the speakers are tuned to. The -3db point will be a few HZ lower (if memory serves the -3db point is 28hz on the "port closed w/eq" version). But that freq comparison should 'show' you the difference.
But looking at what Peter says above"The first mode was where the two ports are open. A bit strange at first but that increases the tuning frequency to 44Hz. With one port covered the tuning frequency lowers (at the cost of some increased port air velocity) and then the eq comes in. Port and eq are tuned at 31Hz."
So, if it works as the engineer says, the difference between "port closed w/eq" and "port open w/out eq" is the same as the difference between F1 (44hz, the lowest F on a piano) and B0 (31hz, the lowest B on a piano). Actually, the speakers will extend a bit below those numbers, because those are the pitches the speakers are tuned to. The -3db point will be a few HZ lower (if memory serves the -3db point is 28hz on the "port closed w/eq" version). But that freq comparison should 'show' you the difference.