Eros Mk II Help

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I'm getting ready to build Wayne Js Eros MK II design from I'd love to hear from anyone who has constructed this design on any hints, tips, etc. Of special note, I'd love your input on....

- internal cabinet treatment - what did you do?
- thinking about driving this speaker with either the Monarchy Audio SM-70 or the Odyssey Khartago. Any thoughts?
Modified Eros

A few years ago I built the Eros speakers. I built them first with the serial crossover but after listening for a few weeks I built the original and find that to be the best. I also redesigned the cabinets to have curved sides to eliminate standing wave inside. My boxes are made of 1” solid red oak sides and tops with 1 ½” MDF fronts, backs and bottoms. I also made different bases for them. I made my own printed circuit boards for the crossovers and mounted them in the bottom. These are some of the best sounding DIY speakers I have heard so far and I am glad I spent the time and money to build them. I have attached some photos so you can see the design changes and the insides before I sealed them.


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Modified Eros

The sides are 1” thick red oak stairs from home depot. I cut the stairs into 1 1/2 “ strips length wise with a 1.5 degree angle then re-glued them back together. This caused the curve. These were then glued to the MDF curved braces. This was all designed in AutoCad and I still have all of those files. The internal volume still matches the original Eros. The foam is a $7.00 mattress pad from K-Mart. The front, back, and bottom are two layers of ¾” MDF press glued together.
The sound of the serial crossover was a little thin in the mid and bass range. After leaving them break in they still seemed thin. I built other circuit boards with the original crossover and put them in. That really filled in everything and I never went back. I still have the crossovers that are in the pictures somewhere but will not be using them. These things are heavy. There are five 1” oak steps and two full sheets of ¾” MDF in each of them. That and the crossovers make it a two man job to carry them. These really are a great sounding speaker. Although mine look different then Wayne’s they are the same in every way except shape.
As far as power goes at this time I am using a Marantz PM7200 50 watt Class “A” amp. They could use a little more but in that small of a room they are fine. When I put them in my main music room I use a Rotel 1090 370 watt amp and they really sing.
great idea with the oak.
so the parrallel sounds warmer does it? i believe one of the crossovers was designed for tube amps.
i might be interested in the other crossover if you want to part with it. i intend to build a set one day.
have you played with more or less stuffing? that might impact the upper bass/mid region also.

I’ll have to look and see if I can find the crossovers. I used Jantzen 12ga. foil coils and Mil resisters. One of the more important capacitors is also a high grade. It has been about six years since I built these. I read on these sights that you should not use hardwoods due to splitting. The stairs rarely split because they alternate the grain direction with each 2” board they are made of. When I cut them I also alternated the 1 ½” pieces before re-gluing. So far I have two sets of speakers (the Eros and a pair of DIY electro stats) made from oak stairs and neither has any problems. In the picture with the pink stuffing you can see the electro stats behind them. After all we have hundred year old stairs in our house and none of them have splits. Red oak is very tough stuff that’s why they make stairs from it.
The stuffing was just a guess and I did not think it mattered because the tweeter appears to be sealed. Are you supposed to remove the back or something? I would change it but these things sound great as is. I also never played with the port length. Are you sure you want to use the serial boards. Even Wayne tells most people to use the parallel ones. As I stated I have tried both and prefer the parallel ones. I have played them with solid state and a 50 watt K-88 push-pull tube amp and definitely like the sound of the originals. Check back after the holidays and see if I can find the crossovers. They are somewhere in the basement and I don’t know what the copper looks like by now. If they are still good I’ll make you a deal.
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no, don't take the back off the tweeter enclosure. i was referring to the stuffing in the woofer section. adjusting this will affect the boomines/tightness of the bass. adjust to personal preference.

you did it right by laminating pieces of oak together. splitting generally only occurs with larger pieces of hardwood.
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I have my components and hardwood ready to go to build these. I dot think I will try to do curved sides, I planned on a trapezoidal footprint to offer a similar solution to standing waves.

I have not yet ordered the XO parts but was planning on using the series design myself. Many of the parts are similar as I recall.

I notice you mentioned you had a pair of these series XOs you won't be using. I could certainly use them right now if the other individual does not take them....this is of course if you are willing to sell them. I was actually going to get on partsexpress this afternoon and order all the components.

Very cool curved process, had I seen this before I bought the wood and veneer I will be using I might have tried this. They are beautiful.
As I stated earlier I have to try and find the crossovers. I hope the copper is in good shape. We are doing a lot of traveling over the holidays so it will be after till I get a chance to look. If you are in a rush then go ahead and order your parts. As I said I do not Know what shape they are in. It has been six years. Our basement is fairly dry so they still may be good.
Actually my wife pointed me in the right direction and I have found the crossovers. They were in a tupperware container and are in great shape. I am not familiar with how things are sold on this sight. I do know the 4 Jantzen 12ga coils alone are worth at least $150.00. They also have Mil resistors and one of the important caps is a Solen. I would probably let the pair go for $100.00 plus shipping. Maybe I should place them on Ebay. You guys are the only ones who know what they are. If I get a chance I will take new pictures and put them up for a flat bid. I have never sold on Ebay but only bought. Just bare with me on this.
Blue934 was so kind to let me take these for your buy it now. Thanks so much for putting them up for sale so quickly. In the spirit of DIY, if I decide to go with the parallel the they will be sold to him at today's price, should he still want them.

When I get done I will post a few pics here for everyone. I anticipate 2-3 weeks.

Thanks again!
I will try and get them out Monday but with Christmas so soon I don’t known when they will get there. I have marked the input and outputs with a sharpie. Keep in mind that the plus for the Bass connects to the same point that the minus for the Tweeter goes. The plus and minus inputs are on opposite sides due to the parts layout. There are five mounting holes and I used aluminum standoffs to mount them. I have sent you an Email so if you have any questions just use it to reach me. I will be away for the holidays so it may take a while for the response.
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When you were talking about the stuffing I thought you ment the cavity behind the tweeter. I'm not shure why the tweeter has a box because it appears to be sealed. I did put some stuffing in it to help stop ringing. With the box being ported I don't know if you should use stuffing in the main area. I used the pink stuff to eliminate reflected waves. It is fairly transparent to the lower freqs though.
I managed to get them shipped today (Monday) and paid for the Priority Shipping (2-3 days). You should have them no later than Thursday. Please let me know if they arrived safely. I also sent you another Email but do not know if it is an active account.
Can anyone confirm which of the resistors in the series XO is the main attenuating resistor? Is it R10?

Here is the link: Project/mk2final.jpg

I am thinking of using an old stepped attenuator switch off an old Lpad, replace the resistors to give myself a range of about 3db up or down, and replacing the stationary resistor with it.

This is one of the setbacks to using a serial design. The tweeter is in series with bass. That means anything you do to the tweeter will also affect the bass to a certain level. Adjusting the tweeter up or down will also adjust the bass up or down although not equally.
Yes, but doesn't pure resistance mostly affect the higher frequencies? If you look at the schematic you have a path for the lower frequencies around this resistor through L7. I can't see how R10, with L7 paralleling it, would attenuate the woofers much, if any at all.
If I am wrong, please tell me why.
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