MJK OB over H-Frame finished

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Greetings!

I have finished putting a Fostex FE103E on an open baffle over an Eminence Alpha 15 in an H-frame (both on the same baffle). This is based on Martin King's papers "Designing a Passive Two Way Open Baffle Speaker System" and "Comparison of the Bass Performance of Passive Open Baffle, U
Frame, and H Frame Speakers" that I found online.

My Polk Monitor 7's that I bought back in college were starting to make noise on hard hits, looking at how expensive a good pair of new speakers would be I decided it would be better to rebuild. I didn't want to be stuck w/o anything besides my iMac to listen to music with, so I decided to try my hand at building a pair of speakers that would be a good keep once the Polk's were done. That's when I discovered MJK's papers/this and a few other forums as well. The internet is so cool (it's like a series of tubes;)).

This is my first speaker build and I am very pleased. With all the writing about how Fostex drivers need time to break in, I half expected these to sound horrible, but they are very acceptable right out of the box. I can only imagine what is in store for the future of these as they get more hours on them. I don't have any measurement equipment outside of my MkI E.A.R.S., so I can only say "They sound good to me!" They may not sound as nice as a pair of Dynaudio BM6A MkII speakers, but I wouldn't expect something built on my back patio to be in that league (plus OB is completely different from Near-field).

I was up way too late last night listening to different CD tracks from my library- mostly classical and rock- as well as the Jazz Traditions channel on my dish receiver. They sound fine on everything I threw at them. They sound best with recordings from the concert halls where I work:D.

My thanks to MJK for putting something so do-able online for a beginner to get started! Now I just have to decide how to approach rebuilding those Polks!

cordially,
Graf
 
Congrats on your new speakers. I'm on the verge of building the same open baffle project myself. I already have the eminence woofers so I'm part-way there. Did you change the crossover values since you put the woofer in an h-baffle?

Are you listening to classical on them?
 
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Hello Graf - and Welcome to diyAudio!!!:D:D:D

Congrats on your build and fer-sure we wanna see some pic's!! Plus all the info about cross-overs, cryo treated - silver plated - solid core - silk insulated hook-up wire etc :headshot:

You work in a performing arts center so ya know what the real deal is in terms of "sounds good" - and thus we do await your listening impressions.

My Fostex 167's did need a couple of hundred hours break in before they started sounding right (subjective term) and I'm pretty sure that you will find yours sounding better after a bit of "burn-in" is put on 'em.

There are treatments and tweaks for 'em - see BudP's EnABLE thread if you are daring - and have a steady hand. David D aka "Planet10" has many tricks to make 'em clean up as well. ;)

It's good to see another Southern lad here with us! We keep trying to get enough of us around to start up some meets every now-and-again - there was one near Atlanta GA awhile back but I couldn't make that one - maybe next time.

As far as the "uploads" go -the site is switching over to a new server at the moment and there might be some glitches there - also notice that there are size limits on what you can upload and if you exceed those limits the server will bounce you out.
 
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pic's and stuff

Thanks for the congrats and welcome! Well, I couldn't get any pic's to load up here on the second try so I loaded them up at Imhoof Studios on MySpace.

The cross-over is the only hiccup. I ordered the parts listed in MJK's first paper before I found the second on H-frames (oops). However, I don't think I'm that far off. I'll be able to make an informed decision once these break in and I borrow a real RTA from work. Right now I've only got the free iPhone app and my ears, but I don't see (or hear) any real problems. Since the cross-over is in the open on the back, it won't be a big deal to change if necessary. No fancy wires. Just the cheap Radio Shack 16ga speaker wire throughout.

I'm driving these with an Onkyo TX-8222 stereo receiver fed from a Sony DVD player or from my dish receiver. I work in a place with two concert halls that have world class acoustics so I'm not even going to try to compete with that in my living room.

These speakers sound really good with less than a dozen hours on them. So far, the only thing I can criticize is the "tightness" of the sound. As I listen to recordings made in our concert halls I can here every note, but not the halls themselves. A recording of Sasha Cooke (mezzo-soprano) w/ Pei-Yao Wang (piano) in our recital hall sounds wonderful- every note/syllable/vowel is right on, but once it's done I don't hear that characteristic hall sound that I'm used to. Same problem when I listen to a recording of the Helsingborg Symphony Orchestra playing in our big hall. Everything is there but the after effect. I can always tell when our halls are played on PERFORMANCE TODAY, but with these speakers I just don't have that. I think that once these things get more hours and relax, I think that will resolve itself.

When I say everything is there, I mean the balance of these is very realistic. I know a lot of people have stated that these need more bass, but I hear the same amount of base out of these that comes off a stage. I wouldn't recommend these for Home Theatre, but that's not what they're made for. I like this design because it lends itself really well to acoustic music. This makes them a really good pair of speakers for over 50% of what I listen to- concert recordings. Once these are broken in and I decide what tweaks I want to commit to, I see many, many smiles in my future. Especially when I remind myself of how much money I spent on these things- WITH costs for tools I don't think I spent $600.

Please let me know if there is a problem finding the pic's at Imhoof Studios.

Cordially,
Graf
 
oops. Earlier post should read less than $600 WITHOUT tools. Thinking it through, I'm not sure I broke $550. Obviously not the least expensive build in history, but I'm happy with this result. I would never spend the money, but I would really like to hear what those Jamo 907's sound like in a synergetic system.

Thanks for putting that link up, c2cthomas! I grew up a Hoosier, but I've spent the last few years here in GA and before this I lived in Houston, TX. I just keep going where the career takes me. I think I would enjoy one of those DIY meets. Have to be in the summer. I'm silly busy during the school year.
 
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oops. Earlier post should read less than $600 WITHOUT tools. Thinking it through, I'm not sure I broke $550. Obviously not the least expensive build in history, but I'm happy with this result. I would never spend the money, but I would really like to hear what those Jamo 907's sound like in a synergetic system.

Thanks for putting that link up, c2cthomas! I grew up a Hoosier, but I've spent the last few years here in GA and before this I lived in Houston, TX. I just keep going where the career takes me. I think I would enjoy one of those DIY meets. Have to be in the summer. I'm silly busy during the school year.

1) Now ya have some tools for the next project!! :D
2) Spending $$$$ on sawdust therapy - pricless :D:D
3) Happy with the result - For a 1st try out of the blocks = Grrrreat! :D:D:D

My Uncle "Buddy" was an engineer for NASA down Houston way + an A&M Alumni. Mom and Sis were born in Wichita Falls and Brother in Amarillo. I love Austin Tx and would live there except that I married a Nashville TN Gal and she drug me from Sacramento Ca to where we now live near Nashville. I have lived in many places and find that I have enjoyed returning to the "South". Here in middle Tennessee it's not to hot - or to cold - or to crazy!;)

How's the speaker break in period going? You can speed things up by putting on some AC/DC or Kiss at high volume levels - but somehow I doubt that would be up your alley :no::headbash::rofl:
 
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Been listening to these from the moment I get home from work to when I go to bed. They're starting to get better/smoother. I really like the open baffle sound- very "open" and detailed. Last night I was listening to THE PLANETS and actually started laughing at one point. I've listened to tracks from Green Day, Pink Floyd, Sammy Hagar, Lynyrd Skynyrd, Yes, Sarah McLachlan, Metallica, Eagles, Creed, Billy Joel,... the list goes on and I think these speakers sound fine on pretty much anything I throw at them. I don't listen to rap or country, so I can't speak to that. Last night I listened to them while watching Monday Night Football and it was weird to hear that much detail while watching TV. I'm currently listening to Kenny Wayne Shepherd's 10 DAYS OUT and love the fact that I can hear where the pick hits on every string (I recommend this CD/DVD to anyone even remotely curious about the blues).

I'm having my Stage Manager and Production Asst over for dinner tomorrow so we can have an end of the semester postmortem meeting and listen to some music that they will be bringing. Should be good to get someone else's ears on these for an objective critique.
 
I'm having my Stage Manager and Production Asst over for dinner tomorrow so we can have an end of the semester postmortem meeting and listen to some music that they will be bringing. Should be good to get someone else's ears on these for an objective critique.

I will be very interested in their opinions. I am always looking for constructive feedback to improve my next design.
 
a couple of different ears

Okay. I had my staff over for an end of the semester postmortem meeting. Grilled Rib-eye w/ broiled potatoes and carrots. We each brought a half dozen glass bottles filled with hoppy goodness as well:)

We listened to these speakers before and after dinner and I made them each write notes in notepads I gave them when they arrived. I'm such a horrible boss!

We listened to many different styles of music: moderne'; wind ensemble; rock; orchestral; chamber; country; blues; bluegrass; a capella; and ended the night with the title track from Pink Floyd's WISH YOU WERE HERE. The drivers had about 35 hours on them at the beginning of the evening. They were definitely smoother and balanced then when I first fired these things up last Saturday night.

My Production Asst started out the night feeling that the low end was not as full as he would like, but by the end of the night he had changed his mind. He hasn't done much critical listening so far, so my guess is his ears are more conditioned to what he hears on the radio. He liked the sound of the drums and guitar with Green Day. Bluegrass got a checkmark with the banjo sound getting 2 checkmarks (this was the Stage Manager's CD and neither of them wrote down the artist). Dixie Chicks (female vocals over all) were very well liked. A capella got two checkmarks with a note that he could tell the St. Petersburg Male Choir was definitely recorded in our main concert hall. Pink Floyd WYWH: "best I have heard that song."

Stage Manager has more recording/critical listening experience and he didn't write down each track. He just wrote notes as the night went along. "-frequency response is awesome - no perceived directionality - I'm jealous - *tympany (+drums in general) sound very crisp - great shimmer on cymbals (smaller rolls) - no noticable loss in HF - 15" woofer is NOT muddy - trombone popped out a bit in wind ensemble - mandolin, guitar, banjo sound life like - female vocals sound natural + good throughout - vocals (a capella)!!! - heard every detail in intro to WYWH"

It's funny, but it appears that as more hoppy goodness was consumed, the stranger their handwriting became:rolleyes:.

I would judge these as a success story!

Currently listening to a 1961 recording of Beethoven's 9th by the Chicago Symphony Orchestra and Chorus w/ Fritz Reiner conducting. I traded my 1987 recording w/ George Solti to my Stage Manager so we could compare the two conductor's approaches. Both very good... slightly different... but both VERY good.
 
We need a 'new vocabulary' section !

I sometimes find some lovely new words or phrases from members. We should use these more often!

Maybe we can kick start it with this lovely one from Gvimhoof...
A bottle of " hoppy goodness ". If it's too long one could sometimes shorten it to " hoppy Goo ?"
Bring along your six pack of 'hoppy goo' to the party ? No....maybe 'goodness' sounds fine !;)
 
I see MJK's account "disabled at member's request" (?!?!) but I'm VERY interested in trying a similar build.

Does anyone know if there has been any advancements in this design, something I should be aware of before ordering parts and making a bunch of sawdust?

I too like the H-frame concept as according to MJK's paper on the topic it should produce a few db deeper bass extension over a conventional OB?

Anyone lived with this build for an extended time able to share such an experience? What would you do different? What would you build if you could do it all over again with the same sort of budget?
 
I'm currently listening to Kenny Wayne Shepherd's 10 DAYS OUT and love the fact that I can hear where the pick hits on every string (I recommend this CD/DVD to anyone even remotely curious about the blues).

gvimhoof! Your build thread and feedback *greatly* inspired me to put my own H-frames together and I love them! But I also wanted to comment on your recommendation for "10 Days Out" which I followed. I'm not sure which one I like better... the CD or the DVD! Certainly fascinating movie and it sounds fantastic too! Thanks for the heads up and so well documenting your experiences with these wonderful speakers!
 
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