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DIY Hybrid OB Bookshelf Has Started

PR Audio

PR Audio

Super Member
Well, After approx. 1 yr. with the drivers and parts laying around I finally decided to start my Hybrid Open Baffle Bookshelves, since looks, location, and size are important, compromises had to be made. In order to keep them as compact as possible a HiVi M5N 5" Wooferin a Ported Box will be used, along with a 4" Mark Audio CHR70.3 Full Range Driver in a folded Open Baffle configuration.

Ported Box is 7-1/2" Wide x 16" Tall (10" is the box baffle and 6" the OB, all one piece)x 9-1/4" Deep with a 1" Dia. x 2-1/16" Long Vent. This box shall give an f3 of 58Hz and an fb of 54Hz. Total capacity is 0.25 cu.ft. (7.07 Lts). I tried to dimension the box as per the Golden Ratio, but because of aesthetics a compromise was made.

OB is folded with a height of 6", and a total length of 10-1/2". According to simulation on the Edge software this only gives me a 2.5dB rise starting at around 456Hz peaking at around 1,200Hz, and dropping back to same level as it started at around 3KHz, it is not more than 2.5dB and the rise and fall are fairly "soft" like a table top curve, not a quick peak, so not much worried about it, but I'm sure that others here will find flaws and comment.

For the enclosures I'm using 1/2" MDF that will be veneered. I will seal the seams of the enclosures from the inside with some kind of silicone or caulk.

Prior to building a passive x-over for them, most probably a 2nd order, but open to your suggestions as not an expert (self-taught on this matter), I will use a Behringer 2-3 Way Active X-Over to dial the frequencies. My intention is to cross after 460Hz, this will be my starting point, but obviously I will experiment going lower and/or higher.

Bi-Amplification and sources will be sort of a mixed bag of a Conrad Johnson KT90's 75WPC Power Amp, DIY 80WPC @ 8 Ohms Class D Solid State Amp (I have a thread with the build somewhere in AK), McIntosh MX-113 Pre-Amp, Jolida JD603 CPD, PC with Audioquest Dragonfly DAC, and Rega P2 TT slightly modified with a stock Grado Gold Ctdge.

The worst that will happen is that I have to trash them, and move on to another project using those drivers, from a $35.00 4'x8' MDF panel I have made a pair of TABAQ's, a 2 pairs of uFonken, the Hybrids I'm building, and still have wood for another set of hybrids or bookshelves for a 5-1/4" Two Way or maybe TABAQ's or 2 more pairs of uFonken.

Any suggestions are welcome, especially when it comes to x-over design and components. I think I will build, use, then start the veneering process.
 

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I think you will like the HiVi's. I have a pair of Overnight Sensation kits from PE that use them. Very nice sounding. :yes:
 
Lavane said:
I think you will like the HiVi's. I have a pair of Overnight Sensation kits from PE that use them. Very nice sounding. :yes:
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Yes, did a lot of research on a 5" to 6-1/2" woofers that would fit my needs, like I said had to do some compromises, decided on the HiVi M5N because a few factors, it could put out decent bass, it is highly regarded and liked, didn't need a large enclosure, and it's color goes well with the Mark Audio champagne color; one thing the wife asked was for them to be aesthetically pleasing.
 
Lavane said:
Any pictures yet? :D
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Have been extremely busy...I have only been able to partially complete one of the enclosures. A/C at my garage/workshop broke down, so I have been working outside. Enclosed is a picture of the almost finished enclosure (upside-down). Was going to finish it today, but remembered that the tools I need to do the opening in the back for the bi-amp binding post cup is at my father's house, so I need to go there to get it; a short 15 minute ride. Also, the cups are almost as long and wide as the back panel of the enclosure, so don't know if I will use it, maybe I will, and spray rubberized undercoating as it is plastic, might not be a big deal anyways.

Here is a pic of the enclosure...
 

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On The Home Stretch....

I think I only have a couple of days of work, and I will be done with the Hybrid OB Bookshelf Speakers. I still need to finish veneering the cabs, then oiling, and some small details. For my first veneering job, and having to do a lot of bookmatching (the baffle is four pieces of left over veneer), I am happy with how they are turning out, not extremely happy, but satisfied. Having problems with the veneer, which I will post in the DIY forum, as to solve.

BTW, the OB part (top of baffle) is 7-1/2" Wide x 6" Tall...I ran some simulation, and I should extend the width to about 10" Wide (to be achieved with side wall extensions). Should I just leave it at 7-1/2" Wide and play with the crossover?

Here is a pic of how it will look from the front..
 

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Nice work PR,

It seems like yesterday that we discussed the hybrid and I'm shocked to learn it's been two years. Oh well good projects take time and I feel like you're finally getting there.

If you've already cut the 7 1/2" baffles then I wouldn't worry about it. Otherwise go with the 10" width. If you go smaller you can usually compensate with the active.

Will you be using a sub? Your Behringer has dedicated sub connections and controls and one could be hidden from view. I just built the bucket sub and have it connected to the Behringer and am highly impressed. It's sounds great and I haven't even added the concrete yet. :D

As I recall size was an issue and that's why you went with a smaller hybrid design rather than big OB woofers. Will be following this thread for sure.
 
Poultrygeist said:
Nice work PR,

It seems like yesterday that we discussed the hybrid and I'm shocked to learn it's been two years. Oh well good projects take time and I feel like you're finally getting there.

If you've already cut the 7 1/2" baffles then I wouldn't worry about it. Otherwise go with the 10" width. If you go smaller you can usually compensate with the active.

Will you be using a sub? Your Behringer has dedicated sub connections and controls and one could be hidden from view. I just built the bucket sub and have it connected to the Behringer and am highly impressed. It's sounds great and I haven't even added the concrete yet. :D

As I recall size was an issue and that's why you went with a smaller hybrid design rather than big OB woofers. Will be following this thread for sure.
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Thanks! Yes, time flies by, I also thought it had been about a year or so.

I will leave the 7-1/2" width then, if needed I will compensate with the X-over. Didn't know about the Behringer having a dedicated sub-out connection, as it has been sitting in it's box since purchased about 18 months ago. I have a very nice sounding 8" 50W Audio Source sub that at one time I used as my main HT sub (Dual 12" DIY sub for HT now). These days that sub serves as PC audio sub with my DIY 3" uFonken or DIY 3" TABAQ. It is a 1998 sub which is not considered "audiophile", but it is much better than many "high-end" subs I've heard. It is tight, well controlled, nice bass detail and good separation of the lower register instruments, actually, it is very musical. If needed I will use it. But, in my listening room I have large gains in the bass region, due to the all concrete/ceramic floor/glass windows construction of my home, that is why I have said many times that my PSB B15's (5-/14") sound better than my PSB B25's (6-1/2") in such conditions. So, I might not need a sub. Anyways, might be the perfect excuse to build a 6" to 8" sub for my PC, and move the Audio Source to the listening room.

I will keep working on veneering today, it has been not difficult but tedious. Hopefully by mid-week they will be all finished. And, yes, size was an issue, I don't have the necessary space for real OB's, and I have to keep the speakers close to the wall, no more than 12" to 18" separation from the wall, hence why front ported also.
 
Thanks for posting this thread. I was considering a similar hybrid since space is also limited here. Very interested to hear about the final outcome, hoping for the best.
:lurk:
 
valvenator said:
Thanks for posting this thread. I was considering a similar hybrid since space is also limited here. Very interested to hear about the final outcome, hoping for the best.
:lurk:
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I went back and forth with different design ideas, but this one seemed the easiest, and since I have stands they would make a good fit. Having said that, I'm still playing with the idea of building a floorstand speaker pair with 1 ea. 5-1/4" to 6-1/2" side firing [URL="http://www.parts-express.com/dayton-audio-sa70-70w-subwoofer-plate-amplifier--300-784"]active sub woofers[/URL] in a vented enclosure with 1 ea. 5" to 5-1/4" woofer, in a sealed enclosure, 1 ea. 3" Full Range Driver in OB, and 1 ea. Planar Tweeter in OB, all in one tower. It would make for a tower of approx. 8" to 9" in width with a depth of no more than 12", and a height of 36".
 
The project is coming along fine, veneering the enclosures has slowed me down, as it being my first veneering job it has been a learning process, especially since I have had to do a lot of bookmatching using bare back walnut veneer.

Anyways,
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, once enclosure is done (not in the picture), and one only has the baffle veneered and does not have the back panel glued yet, but all that should take a day or so.
 
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Almost at the finish line!

Waiting on banana posts that I ordered from MCM. But, the Hybrid OB's are almost done, just need to install the posts and solder the wires, and enjoy.
 

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So, finally finished the Hybrid OB Bookshelf speakers...The last parts needed, which were the banana posts, arrived today via USPS.

So, the question is: How do they sound?

1. They don't have a crossover, as I will use an active crossover.
2. At this time I can't bi-amplify to use the active crossover, as one of my amps is being modified, and waiting for a part that will arrive sometime early next week.
3. Since I was desperate to hear them I ran them for approx. 10 mins. with my 80WPC Class D DIY Amp, McIntosh MX-113 Pre, and Jolida JD602A CD Player.
4. The HiVi M5N can be run full range, and obviously the Mark Audio CHR70.3 can also be run the same way. So, I bridged the bi-amp posts to use them with one amp.
5. The drivers are fresh out of the box, so no break-in time.

The Sound: Initial impressions are favorable, balanced, but the upper mids-highs are somewhat augmented. The mids are extremely clear and very detailed, highs from the Mark Audio are crisp, airy, clear and also detailed, though it will benefit from less gain and crossover; will work on that tomorrow. Soundstage is deep and wide, and imaging is amazingly good, the speakers totally disappear with the instruments well placed in the soundstage. At ear level they are a little brighter than what I'm used to, but I have always liked warm sounding systems, this are not that bright, it is just that there is a lot of information being conveyed by the speakers; very coherent though. If you place the Full Range driver slightly above the ear the sound gets less bright. These are very dynamic and fast speakers. Bass quality is excellent, not boomy at all, and at the same time they don't lack bass. I ordered a measuring mic from PE, it will get here Monday or Tuesday, I will take measurements them.

Looks: Judge for yourself I enclosed pics in previous posts and this one. The golden shade of color of the HiVi is almost identical to the Mark Audio color, making for a very appealing speaker.

Hopefully I can hear them better in the next hours and tomorrow. I will update then.
 

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Quick Update: Just noticed that the tone controls in the amp were set to negative on the bass and positive on the treble; my PSB B25's in my room are boomy and lack highs, so I had the tone controls set that way, which were perfect to make the B25's sound like they are supposed. So, toned down a a notch or two the treble, still in the positive side, and brought back to neutral the bass knob; now the Hybrids sound as they are supposed to, and WOW!!!! This speakers are not only balanced, but the clarity is beyond belief. No "S" factor on the voices...This might be bragging or just proud because they are DIY, but their sound reminds me of one of my favorite speakers, the Revel Performa3 M105; big words but you need to experience it yourself! Feel free to to build a pair (0.25 cu. ft. enclosure with 1" x 2" vent, and 7-1/2" Wide x 6" Tall OpenBaffle on top of the enclosure). I didn't use any liners for the inside walls, and so far haven't noticed needing them, but if you use a damping liner adjust dims. for them.

Poultry: A crossover might not be needed, according to models for BSC I should cut the drivers at 608 Hz, but the two drivers blend in rather nicely.
 
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