CLS,
yes, that "Dipole positioning and room modes" thing is from me. And no, I havn´t listened to the Helsinki.
I can follow what you experience in your room. And I certainly experience myself how my toed-in dipole bass is focused to my listening position compared to the regions outside. But IMHO you/me did not walk through/into the dipole null, but through different room mode zones mainly. I will try to explain:
At 34 Hz wavelength is 10 m. I believe that in usual rooms this is much to large to develop a noteworthy dipole figure 8 pattern. But since dipoles are directional velocity sources they can excite (or even subdue) room modes in different ways. How they do this can be quite different, depending on whether you look at single dipoles or at stereo pairs.
When a single dipole is positioned parallel to a room axis, it will mainly excite (or subdue) room modes along that axis. Which of those modes are excited the most, depends on the position on that axis. Modes perpendicular to that axis are excited less - but they will be excited too. With some toe-in the dipole will excite/subdue modes on both main room axes to a comparable degree.
When a pair of stereo dipoles is aligned along a room axis, it will excite the modes along that axis in the same way as a single dipole. If the pair is toed in, it will develop a very different behaviour along the perpendicular room axis, because now both velocity vectors are not in parallel, but have opposing components. With much toe-in I am able to completely switch off the lowest room mode along the axis connecting my H dipoles (that's the room breadth), but leaving quite a bit of that mode perpendicular (along the room depth axis).
Could this explain what you decribe as "... far off-center positions..." where "... bass is relatively weaker..."?
Rudolf
yes, that "Dipole positioning and room modes" thing is from me. And no, I havn´t listened to the Helsinki.
I can follow what you experience in your room. And I certainly experience myself how my toed-in dipole bass is focused to my listening position compared to the regions outside. But IMHO you/me did not walk through/into the dipole null, but through different room mode zones mainly. I will try to explain:
At 34 Hz wavelength is 10 m. I believe that in usual rooms this is much to large to develop a noteworthy dipole figure 8 pattern. But since dipoles are directional velocity sources they can excite (or even subdue) room modes in different ways. How they do this can be quite different, depending on whether you look at single dipoles or at stereo pairs.
When a single dipole is positioned parallel to a room axis, it will mainly excite (or subdue) room modes along that axis. Which of those modes are excited the most, depends on the position on that axis. Modes perpendicular to that axis are excited less - but they will be excited too. With some toe-in the dipole will excite/subdue modes on both main room axes to a comparable degree.
When a pair of stereo dipoles is aligned along a room axis, it will excite the modes along that axis in the same way as a single dipole. If the pair is toed in, it will develop a very different behaviour along the perpendicular room axis, because now both velocity vectors are not in parallel, but have opposing components. With much toe-in I am able to completely switch off the lowest room mode along the axis connecting my H dipoles (that's the room breadth), but leaving quite a bit of that mode perpendicular (along the room depth axis).
Could this explain what you decribe as "... far off-center positions..." where "... bass is relatively weaker..."?
Rudolf
Maybe the trick of the Gradient Helsinki is that that glass/plexi fin on the back of the MT arm? Does that change how things sum to the front or at least at the listening position?
Just like offsetting a mid/tweeter changes on/off axis response, at a given point in space, the woofer is effectively offset in a baffle which is 90deg from the plane of the mid/tweet?
I can't make it work in Edge without a toe-in. But seems it would take serious EQ and power to do it?
Just like offsetting a mid/tweeter changes on/off axis response, at a given point in space, the woofer is effectively offset in a baffle which is 90deg from the plane of the mid/tweet?
I can't make it work in Edge without a toe-in. But seems it would take serious EQ and power to do it?
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Hi guys, I'm still working on mine MJK H-frames with OB's created using the Edge.
Almost finished the design of one of the speakers. I use Cork and synthetic leather glued with Henkel Moment Universal.
The cork layers on the OB are 3x3mm around the midrange and 2x3mm around the ribbon tweeter. - this in order to make the speakers flush with the front surface.
I don't know what the effect should be, but it seems to me that the sound became more open, natural and even more linear... I'm very happy!
I'm planning to make the rear opening in the baffle for the midrange more slant and wide using rasp file.
For my upholstering skills and considering the fact that I'm not very pretentious and that this is my first upholstering, I'm very happy with the result! Also because of the 3 layers around the midrange and the 2 around the tweeter I got a seamless curvature which I like - marked in green circle in one of the photos.
I also did something completely non-scientific, or anti-scientific... actually it is almost something audiophilic bordering to superstition...
... well: I left two small chambers in the second layer of cork around the midrange... hoping it will enhance the reproduction of solo drums...
and actually solo drums sound better now
but is it due to those chambers? Just the pieces of cork left from upholstering of the H-frame were sized in a such way that it lead me to that conclusion... I had all needed material for full 2nd layer, but decided to give it a try...
Now when you test with knocking with finger the front surface this area gives a sound similar to solo drum... and solo drums sound better and more natural...
Is this a sonic crime what I did?
Here are some photos:
(the chambers are in green circle in the close up and in red from side)
Almost finished the design of one of the speakers. I use Cork and synthetic leather glued with Henkel Moment Universal.
The cork layers on the OB are 3x3mm around the midrange and 2x3mm around the ribbon tweeter. - this in order to make the speakers flush with the front surface.
I don't know what the effect should be, but it seems to me that the sound became more open, natural and even more linear... I'm very happy!
I'm planning to make the rear opening in the baffle for the midrange more slant and wide using rasp file.
For my upholstering skills and considering the fact that I'm not very pretentious and that this is my first upholstering, I'm very happy with the result! Also because of the 3 layers around the midrange and the 2 around the tweeter I got a seamless curvature which I like - marked in green circle in one of the photos.
I also did something completely non-scientific, or anti-scientific... actually it is almost something audiophilic bordering to superstition...
... well: I left two small chambers in the second layer of cork around the midrange... hoping it will enhance the reproduction of solo drums... and actually solo drums sound better now
but is it due to those chambers? Just the pieces of cork left from upholstering of the H-frame were sized in a such way that it lead me to that conclusion... I had all needed material for full 2nd layer, but decided to give it a try...Now when you test with knocking with finger the front surface this area gives a sound similar to solo drum...
and solo drums sound better and more natural...Is this a sonic crime what I did?
Here are some photos:
(the chambers are in green circle in the close up and in red from side)
Attachments
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Whew! I just finished this whole thread over several days, so as not to miss anything important, as well as a few other related threads and articles.
As interesting as the thread was (very), perhaps the introduction to Eva Cassidy was the single most valuable item.
Thanks to all contributors, particularly MJK.Off to buy parts.
Hi Godzilla
I was still getting nowhere on my new 'bass' speakers, untill I saw your 'H' build, and followed it to MJK's site & from there to here !
This looks great !
No matter how bigger driver, box or whatever I was considering for my project, It simply didn't add up on paper to 'audiophile bass speakers'.
It just = expensive low Q drivers, huge heavy cabinets, compression drivers & rediculous waveguides & still not enough smooth quality low end.
Well, it looks like all that's out the window here ! Loads of low smooth bass, no back-ache & deafening 110dB comp. drivers, marvelous !
How is your 'H' setup sounding to you at the moment ?
All that 80s' synth stuff coming on strong seems like a good rec.?
Cheers
Simon
>>> It just = expensive low Q drivers, huge heavy cabinets, compression drivers & rediculous waveguides & still not enough smooth quality low end.
This forum is GREAT for discussing ideas for projects. Your project was ambitious and difficult to accomplish. I think it can be done! But it will require big boxes and expensive components.
The H-frames still sound AMAZING to me. Others have built them with more expensive drivers and equalization. That's a turn off for me but it doesn't mean they are not achieving even better results. I prefer simpler projects and accept their performance levels... which could be quite high IMO.
I've said it before, H-frames have given me the best bass in my listening room. They are lightweight 'boxes' also used as stands. But they are clunky looking.
I just finished a very modest pair of BIBs that came out wonderfully! They just sound much more expensive than the parts used. I am so happy with them that i actually plan to finish them with stain or paint.
My next project will be something like this:
Endorphine from Kingston Kitchen
I plan on using the Eminence 12lta as the main driver on open baffle, the same compression driver tweeter i've used in other projects and the Alpha 15's... in what looks like a U-frame rather than an H-frame. I expect the results will be very good and hope the look will be less clunky in my space.
But if you can accommodate H-frames and use them as stands for the main speakers, i really don't think you can get any better in terms of sound quality regardless of price... unless you double them up two H-frames per side... this great hobby is limitless!
Zilla
This forum is GREAT for discussing ideas for projects. Your project was ambitious and difficult to accomplish. I think it can be done! But it will require big boxes and expensive components.
The H-frames still sound AMAZING to me. Others have built them with more expensive drivers and equalization. That's a turn off for me but it doesn't mean they are not achieving even better results. I prefer simpler projects and accept their performance levels... which could be quite high IMO.
I've said it before, H-frames have given me the best bass in my listening room. They are lightweight 'boxes' also used as stands. But they are clunky looking.
I just finished a very modest pair of BIBs that came out wonderfully! They just sound much more expensive than the parts used. I am so happy with them that i actually plan to finish them with stain or paint.
My next project will be something like this:
Endorphine from Kingston Kitchen
I plan on using the Eminence 12lta as the main driver on open baffle, the same compression driver tweeter i've used in other projects and the Alpha 15's... in what looks like a U-frame rather than an H-frame. I expect the results will be very good and hope the look will be less clunky in my space.
But if you can accommodate H-frames and use them as stands for the main speakers, i really don't think you can get any better in terms of sound quality regardless of price... unless you double them up two H-frames per side... this great hobby is limitless!
Zilla
As I troll these forums often, since my actual participation in DIY has been about nil for the past 4+ years, I see things I recall I've sketched on in the past. Zilla, that which you have posted is the 'big' project I had started before moving and realizing I don't really have the space for it. With over $1k worth of drivers, crossover parts, etc., and almost finished boxes sitting in my basement, I'm determined to get back to it. However, I think I'd like to get into a pair of Alpair 10 Pensils for our living room first. Never enough time, farrrr to many ideas.
Hi Godzilla
The great thing about the 'H's compared to standard BR 15/18" cabs. is they don't weigh much & hardly take up any space, + no doubt much better, super-low, non-boxy bass.
For use in the studio, quality and smoothness rather than ear-shattering gig volume is what's needed.
If 'Ampeg' tried to sell these to bass players, they wouldn't shift a single unit because they probably don't play loud enough for gigs.
From my point of veiw, I wouldn't give an 'Ampeg' speaker a second look due to totaly poor sound quality & lack of low end.
If they gave me one for free, I wouldn't give it space in the studio.
These 'H's look great, put 'em on wheels, sit on 'em, use them as mobile tables, stack recording gear on top of 'em, DANCE on top of 'em !!!
I can see the Jordan satellite OB's mounted on cast base microphone stands, quick to move to where the action is.
Whole monitor system, on their own as super near-fields, or quickly moved again & setup with an instrument rig. Totaly flexible use.
Even possible to have extra satellite OB's with different drivers, like a cheap 6 or 8" Fostex full-range or a couple of Eminence 6" Alphas.
I've wanted some quality super near-field units like the Jordans for some time, so this gets me them, instead of some annoying comp. driver & waveguide that you can't use for anything else & have to pad down massively. (I have a pair of Ted Jordans first drivers here, the Axiette 8's waiting for mounting, maybe now on another mic stand mounted OB).
I have now read 50% of this huge thread, and the only real issue that is still a bit unclear to me concerns LF driver selection.
The Goldwood 18" as far as I can tell is unavailable in the UK and I have not been able to find an alternate high Qts 18".
This leaves me 2 options, build a low Qts 18 or go with a med-high Qts Eminence 15" which I can get easily.
What I don't understand is whether the mid Qts drivers of 0.48-0.58 are suitable or not.
I understand what Martin says about the frequency drop off on low Qts drivers, the vast majority out there being ever lower at 0.3 or less.
On the thread it has been suggested that if operation is in a smallish room that lower Qts might be more acceptable, letting the room load the driver.
I would prefer to use an 18" driver, but as said before there aren't any ? (anyone know one that I don't ?).
If I was to go for a 15" Eminence, for multi-purpose use without a crossover & general guitar/bass use, the Delta-15LFA would be my choice, for it's much less 'peaky' response at 500-2K Hz, but this drivers Qts is medium @ 0.48
Should I worry about this or is it suitable for a smallish room ?
If anyone has any thoughts on this or has used anything different etc. please let me know.
As for simple, yeah absolutely, the best ideas always are & in my experience have a tendancy to work better, cleaner, easier.
Oh yeah. tube amps were mentioned in the thread and I have a couple of P-P 2x EL84's I would love to use, these might not like high Qts ? Could they be happier with mid level 0.48 Qts ?
Thanks for your thread Martin, I have read your other stuff as well now, nice work, top dude !!!
Cheers
Simon
I'll just put in my 2 cents and let other, more knowledgeable types respond. It's become my opinion that if using high Qts drivers is a problem because of availability, limited choices, or whatever, then the best solution is to use an active crossover/EQ system. With EQ you open up a whole spectrum of available drivers since Qts becomes almost a non-issue. With a device like MiniDSP (maybe other devices too), with which you can crossover anywhere and has parametric EQ built in for all four channels, these problems are solved for around $125. A lot of folks here believe that low Qts drivers have a tighter sound anyway if you can solve the bass response problem with OB's. It is what I'm going to use as soon as it gets here, with a H-framed Eminence 15 and and 8" FR on top. It just makes the most sense to me and not expensive if you use an inexpensive SS amp for the woofers which should be quite adequate (make sure it goes to 20 Hz).
Take a look at this thread as a way to increase Qts - it might help - ymmv.
http://www.diyaudio.com/forums/multi-way/146804-increasing-qts-series-r-ob.html
>>> I'm determined to get back to it.
Go for it one1speed... i hope you get to finish your 'big' project one day. Enjoy building the Pencil's too!
>>> Oh yeah. tube amps were mentioned in the thread and I have a couple of P-P 2x EL84's
I love that little tube... but not for the woofers.
Go for it one1speed... i hope you get to finish your 'big' project one day. Enjoy building the Pencil's too!
>>> Oh yeah. tube amps were mentioned in the thread and I have a couple of P-P 2x EL84's
I love that little tube... but not for the woofers.
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G'day all
I am building a set of these as my first DIY project. I have managed to get the drivers to OZ but I am now having some problems with the crossover components. The inductors are easy as is the 51 uF cap. What I am in a bit of a dilemma about is the 150uF one. MJK's design specifies a 150uF 400V Erse cap, but I can't seem to fine one. The Erse website lists a 150uF 250V cap
ERSE - PulseX
but in the 400V range there is a gap from 130uF to 160uF.
I can see three basic options:
1. Use the 250V cap. This keeps the crossover characteristics but I have no idea of the consequences of reducing the voltage rating.
2. Substitute a different valued cap. This will change the characteristics of the crossover. Will this be noticeable and should I go up to 160uF or down to 130uF.
3. Use two 75uF 400V capacitors in parallel. Mathematically the same, but does this change other characteristics?
Any advice or experience you might be able to pass on would be greatly appreciated.
I am building a set of these as my first DIY project. I have managed to get the drivers to OZ but I am now having some problems with the crossover components. The inductors are easy as is the 51 uF cap. What I am in a bit of a dilemma about is the 150uF one. MJK's design specifies a 150uF 400V Erse cap, but I can't seem to fine one. The Erse website lists a 150uF 250V cap
ERSE - PulseX
but in the 400V range there is a gap from 130uF to 160uF.
I can see three basic options:
1. Use the 250V cap. This keeps the crossover characteristics but I have no idea of the consequences of reducing the voltage rating.
2. Substitute a different valued cap. This will change the characteristics of the crossover. Will this be noticeable and should I go up to 160uF or down to 130uF.
3. Use two 75uF 400V capacitors in parallel. Mathematically the same, but does this change other characteristics?
Any advice or experience you might be able to pass on would be greatly appreciated.
Either the 140 uF 250V or the pair of 75 uF 400V caps in parallel should work fine. Pick whichever is cheaper.
Remember for these large professional bass driver combined with full range driver systems, with low crossover points, SS amps seem to work much better than tube amps.
You should be all set,
Martin
Remember for these large professional bass driver combined with full range driver systems, with low crossover points, SS amps seem to work much better than tube amps.
You should be all set,
Martin
Years ago when I used a pair of 15" Goldwoods to augment the Hawthorne Silver Iris in an OB lot's of people would not believe me when I said they sounded really pretty good. Some people just can't get past the idea that (at times) it is possible to get good sound from low cost components/equipment.
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