Building Two way speakers with Ahuja 12" and Compression driver

[Naveenbnc]

 

[sound_cycle]

I haven't closed the back panel yet. The video i posted was kind of OB

Hi

My interest in OB is from the "user" perspective really and not a design/ DIY one.

My first experience of hearing OB/ dipoles was at FM @drkrack 's and I was intrigued by the sound and all interested in the boxless sound. From a limited reading (aka internet expert perspective) I figure that the nice dipole sound is from the figure of 8, two lobed, radiation which in theory reduces the stimulation of resonant room modes and also gets you high frequencies being reflected from the rear wall (I have not figured how it preserves imaging if the sound is coming at you from all sides)

A dabba without a back would not really qualify as OB I guess, it is a pipe which brings with it at least some of the evils of its boxed forefather (resonance). I've seen your Colors of the Moon yt clip and would suggest that you might like to follow the Maggie recommendation of 10 m/s from the front wall if you are playing them "backless"

ciao
gr

 

[Naveenbnc]

Hi

My interest in OB is from the "user" perspective really and not a design/ DIY one.

My first experience of hearing OB/ dipoles was at FM @drkrack 's and I was intrigued by the sound and all interested in the boxless sound. From a limited reading (aka internet expert perspective) I figure that the nice dipole sound is from the figure of 8, two lobed, radiation which in theory reduces the stimulation of resonant room modes and also gets you high frequencies being reflected from the rear wall (I have not figured how it preserves imaging if the sound is coming at you from all sides)

A dabba without a back would not really qualify as OB I guess, it is a pipe which brings with it at least some of the evils of its boxed forefather (resonance). I've seen your Colors of the Moon yt clip and would suggest that you might like to follow the Maggie recommendation of 10 m/s from the front wall if you are playing them "backless"

ciao
gr

I fully agree. Actually i was joking when I say backless box is an OB.
Everything needs to be carefully designed. I understood that.

And my intention was to make a sealed box.
I kept it unfinished because I have to buy one more sheet of mdf for braces. Il do it when I cut material for my next speakers. Saves time and efforts.

 

[Naveenbnc]

When comparing these songs with Dayton RS-100 (costlier than Ahuja), Dayton outshines Ahuja in all departments but it is not fair to compare apples to oranges.

Hi Vstereo, Dayton RS-100 is 4" full range right?
Did you build speakers with it?
Can you share some details or pics if you don't mind...

 

[diyaudio]

The OB sound is primarily due to the high directivity (narrow 60 degrees) that the figure 8 brings, it separates the direct signal from the early reflections by a wide margin. To make it work the rear radiation must be addressed suitably which is why the minimum wall distance is needed or diffusion or both. This time difference between the direct sound and reflected one gets us closer to the recording.
Boxless sound, resonance elimination (or reduction), box ringing, less excitation of the room modes are also few other benefits but not he dominant ones. Diyaudio has lots of threads on these and the conclusions

A dipole radiation can also be achieved by 2 boxes back to back and will still give the same figure 8 pattern and its qualities. Many cardioid speakers use a combination of OB and sealed (Linkwitz LXMini or Nola BrioTrio) and they dont sound boxy at all.

Similarly the dipole radiation in bass is only valid in the near field, in far field the room reflections come in and the dipole is less effective.

 

[VSTEREO]

Hi Vstereo, Dayton RS-100 is 4" full range right?
Did you build speakers with it?
Can you share some details or pics if you don't mind...

Yes. It is FR 4 ohm.

It was designed and hand crafted by our @diyaudio; bought from diyaudiocart.com. Actually, I was following this driver for many years in another diy forum and while I was deciding to make one myself, I came to know it's availability in diyaudiocart.com. It was a great purchase.

Dayton Audio - PS95 is also popular among DIYer's and I am planning my next project with this.

 

[Naveenbnc]

The OB sound is primarily due to the high directivity (narrow 60 degrees) that the figure 8 brings, it separates the direct signal from the early reflections by a wide margin. To make it work the rear radiation must be addressed suitably which is why the minimum wall distance is needed or diffusion or both. This time difference between the direct sound and reflected one gets us closer to the recording.
Boxless sound, resonance elimination (or reduction), box ringing, less excitation of the room modes are also few other benefits but not he dominant ones. Diyaudio has lots of threads on these and the conclusions

A dipole radiation can also be achieved by 2 boxes back to back and will still give the same figure 8 pattern and its qualities. Many cardioid speakers use a combination of OB and sealed (Linkwitz LXMini or Nola BrioTrio) and they dont sound boxy at all.

Similarly the dipole radiation in bass is only valid in the near field, in far field the room reflections come in and the dipole is less effective.

Thank you diyaudio !!

I still have to understand what this figure 8 pattern is ...
And LXmini is something totally out of the Box I saw recently. Bass driver is pointing up, and the tweeter is facing us !!!!

 

[drkrack]

making it inert will ensure mimimal box resonance.

How about using more stronger materials to build a box, say granite, or concrete etc? Keeping the mdf for the front baffle...

if you see this thread, please add a few words about your observation on "rock music" and "fast beat electronic music" with Ahuja

Ah its pretty bad for heavy metal, soft rock is OK.
I'd keep my OBs with Ahuja only for playing old Bollywood though, it does great work with vocals. If we go by @RavindraDesai design of ported enclosure it might sound better hopefully...
Your enclosure looks very professional, Great job!

dabba without a back would not really qualify as OB I guess,

We can call it BB for easier identification, aka "backless box"

The OB sound is primarily due to the high directivity (narrow 60 degrees) that the figure 8 brings, it separates the direct signal from the early reflections by a wide margin.

Very well put, I felt the whole effect of Soundstage surrounding you all around was basically enjoyable when you're sitting in the narrow sweet spot of OBs . But nevertheless, stereo listening is a individual experience and preference, so narrow sweet spot doesn't matter.

 

[Naveenbnc]

How about using more stronger materials to build a box, say granite, or concrete etc? Keeping the mdf for the front baffle...

Ah its pretty bad for heavy metal, soft rock is OK.
I'd keep my OBs with Ahuja only for playing old Bollywood though, it does great work with vocals. If we go by @RavindraDesai design of ported enclosure it might sound better hopefully...
Your enclosure looks very professional, Great job!

We can call it BB for easier identification, aka "backless box"



Very well put, I felt the whole effect of Soundstage surrounding you all around was basically enjoyable when you're sitting in the narrow sweet spot of OBs . But nevertheless, stereo listening is a individual experience and preference, so narrow sweet spot doesn't matter.

Aaaah... Finally u came in ..

 

[Naveenbnc]

Ah its pretty bad for heavy metal, soft rock is OK.
I'd keep my OBs with Ahuja only for playing old

Exactly. My observation is same. Vocals and slow instrumental music is superb for its price. They can give plenty of treble. But in fast beat music, instrumentals get mixed up, and the sound signature is not of Hifi kind.

Adding a bass driver takes care of low end. But i find the problem lies in upper mids and highs (after the vocals). That's the reason I'm thinking of adding a tweeter and crossing over 3k hz.

Still its surprising for me why it handles the highs in slow instrumentals so wonderfully ....and struggles with rock and fast beat.

 

[drkrack]

for its price. They can give plenty of treble. But in fast beat music, instrumentals get mixed up, and the sound signature is not of Hifi kind.

Not hifi? You should have listened to them playing Spotify with Northstar Supremo DAC, the performance was simply unbelievable. It did a paradigm shift in my thinking about impact of quality of speakers in overall SQ.

Adding a bass driver takes care of low end. But i find the problem lies in upper mids and highs (after the vocals). That's the reason I'm thinking of adding a tweeter and crossing over 3k hz.

I think experimenting with ported enclosure is better before going for XO and Dedicated LF drivers.

Still its surprising for me why it handles the highs in slow instrumentals so wonderfully

Sensitivity matters, any amp supplies more than required current to drive them comfortably. I wish you had witnessed ATC SCM 11s driven by dual Vidar setup. They surpassed all our expectations from premium bookshelf speakers.

For me now its Either
1. Low power tube amp mated to higher sensitivity speakers or
2. Difficult to drive speakers mated to an overwhelming amplification... (whether its a professional or hifi amp, class A or D doesn't matter)
No middle route!

 

[Naveenbnc]

Not hifi? You should have listened to them playing Spotify with Northstar Supremo DAC, the performance was simply unbelievable

Got it.... May be the word not hifi was misleading. I was just refering to only one specific zonor of music where resolution is a bit mixed up. In other areas they are simply awesome !!

 

[Naveenbnc]

Narrow HF dispersion is a common shortcoming with almost all FR drivers. Hence the Phase plug comes to your rescue, provided you are fine with sacrificing your driver during experimentation (just in case) and your carpenter does not shy away building one !!! (Though "belan" is a brilliant idea ! )

The moment you add a bass buddy to your FR driver, the setup starts singing almost all kind of music you throw at it. The only problem with OB is, if the recording is poor, you get to listen "utter garbage" ! And if the recording is top notch, expect to get shocked and goosebumps !!!

Yes, the OB must be built around high dB drivers and the mid-treble must be driven by tube power. (Its not just me saying this, but a respectable old man, which is a TL and box speakers DIY master crafter and has recently discovered the tube magic with OB FR drivers and admitted after all his SS adventures all these many years. He does have a commercial success with his creations up his sleeve, so it was not confined to just his own listening)

I'm still an amateur to fiddle with phase plugs

How ever, i failed to understand how adding a bass driver helps when the problem area is HF dispersion.

To draw an anology.....when an active sub is added to an avr, it shares better power to the remaining speakers. Likewise, if I add a bass driver, the LF burden is releaved and the driver works better in HF area. Is my understanding correct ???

 

[Naveenbnc]

I have zero experience with phase plug DIY but have a fair idea what ii does to HF as I am playing a Japanese driver with a phase plug and have another fantastic FRD but with narrow HF dispersion. So am seriously contemplating to add a phase plug to it.

Learning from others experience from phase plug DIY, I would prefer to add it to a FRD with vented pole magnet. The trick is, not to disturb the cone and seal the phase plug airtight to it, all the way to the back of the magnet pole, so there are no cancellations of sound.

Most of the FRD have their Fs in the range of 75-45 Hz and even if they may be high Qts, for reasonable baffle sizes, the roll off happens around or above 100 Hz until unless your objective is single driver OB. But I believe if you make a single driver OB sing below 70 hz there could be midrange sacrifice because of low end vibrations.

Many audiophiles firmly believe that you cannot do without a sub in your setup and my 2 way OB iterations are essentially adding an OB sub below or around 100Hz , which in my case is doing 35 Hz of useful room response and is quite fine for me. The bass driver does nothing to augment HF dispersion of the FRD but adds warmth to the mids of FRD and with addition of a bass driver, your setup starts handling lows well so all kind of music starts sounding great.

I play FRD unfiltered through tube and because of baffle width, the roll off of FRD below 100-140 Hz is rapid @ 18dB per octave. And the bass driver takes over from there and is played SS.

Thank you so much for a detailed explanation !!!
I will see what I can do.

 

[Naveenbnc]

Take it easy. Above is just to share my own experience and learning. Nothing is carved in stone in audio DIY.

You build your own the way you feel comfortable. There is always time to experiment and learn and there is no stopping if you love DIY. Your own experiments may add to some new findings....

thank you ...whether it's speakers or anything else in my house... I prefer diy

 

[Naveenbnc]

Guys....forget about refinement, upper mids, and fast beat songs. I just tried some movies with Ahuja as fronts. Damn I couldn't believe myself !!!! I was literally laughing after watching a few scenes. My room is almost near to explode . I couldn't even notice if center channel is working at all. I didn't connect any atmos speakers yet. But still the helicopter sounds are totally filled in my room.

And that too...I used my earlier avr from yht196, which is pretty basic.
Ooh...I couldn't explain what a huge impact they made. For music, i may have to work on further refinement. For movies, damn !!! i can't ask anything more. And it doesn't matter even if don't close the rear panel, or add internal braces etc. They are just so wild for action movies

 

[Naveenbnc]

And Im glad that I clearly experienced difference between movies and music. For music we always look for higher refinement. But for movies we can get over with it. Unless our entire setup is highly refined.

Earlier i used some 88db sensitive BS and FS. And many people like me wonder if the avr is struggling to drive the speaker. And usually look for avr upgrades.

And these Ahuja with 97db are very easy for a basic Avr to drive. I drove them as loud as I can bear, and yet there is are no signs of distortion.

Now to compliment these Ahuja fronts, I have to upgrade my sub. !!!

Making them better for music is still a pending task for me now.

 

[Naveenbnc]

If they are high Qts drivers and IIRC its .7 then open back will give you far more musical goodies than sealed back for the current volume. Try it. High qts drivers breathe easy in larger volumes given to them. With open back, they simulate a horn loading from the rear.

And yep, above all, these are 12" extended range drivers and pretty high on dB chart. A few watts must be exploding your room.

Great and satisfying experience today
Il try ur suggestions too. But before that, il add internal braces, and one more front baffle. Later il work on damping and rear panel.

 

[Naveenbnc]

Let me suggest you a simple experiment tomorrow morning. Try that first. Will update with a picture for the idea.

Sure sure ...thank you !!

 

[Naveenbnc]

Your current setup with Ahuja extended range is a kind of dipole with horn loading from the rear. If you are willing, just reverse the mounting of the drivers so that they face inside the box and also place the boxes on the reverse, that is, now the drivers with open rear, mounted on the baffles on the back of the box, will be facing the room. Something like this:

View attachment 30258

Keep them away from rear and side walls and play the same movie tracks and see what difference it makes now and compares in sound, to your present mounting.

I did not ever play extended range drivers like this but only bass drivers and it supersedes everything in bass I have build so far, including the TL subwoofers. It becomes a horn loaded dipole bass and has concert level reproduction. Your drivers have decent 45 Hz Fs, so they might do very well. Just for fun, try it if you wish.

Understood !!
Nothing wrong in trying. Il see if I can do it.
The biggest problem is my room size. Its too small for such big speakers. But il try and see. The boxes should not fall back since all the weight will be outside the box . That I have to take care.