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Calpamos two way

Wharfedale EVO4.1 Bookshelf Speakers

madman29

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After building the THAM15 subwoofer I realised that my focal chorus 726V is not going to match in sound stage with it. So I started looking for a project involving 15" mid woofer and compression driver+horn combo.

I liked the Calpamos project of Humble home made hifi. The FaitalPro drivers were abailable in Calcutta. The stumbling block was the crossover.

Still went ahead and made it. Tried to give it a vintage JBL look:)

Bought a DBx 234xs for crossover.

Playing the mids with Pioneer SA9900 and the compression driver with 2 x NAD 2100.

Still in the process of tuning it properly.
 

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diyaudio

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This one has a diffraction slot, you could have used a conical waveguide instead, you already have active xover so changes were not that difficult
 

madman29

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Basically I played safe and copied the design exactly.
But the problem I'm facing now is the crossover point if I crossover it around 700Hz (as in the original design) I lose precious mid and if crossed over above 1800hz it has a reverse V curve in sound.
I don't know if the original passive xo had any notch filters or not, But with active xo a little bass boost is becoming a must.
One more thing I changed is the length of port. Original design had a port of 63 mm length x 4inch dia. I increased the length hoping it will be tuned a little lower and produce more low bass. Rest of the design is followed faithfully.
Now all this is experiment is done by hearing only as I don't have any sound measuring instrument. Though my old focal floorstanders are there to give me a reference point.

But if I don't complain about the bass they sound way better than the focals. The mids are clear and highs crystal. definitely I get to hear more detail than I used to from my focals.

I have not tried this setup with the THAM 15 subwoofer still as I want to tune those as much as possible to perfection before throwing in the sub in the mix.

Some pic of my THAM 15 project

This one has a diffraction slot, you could have used a conical waveguide instead, you already have active xover so changes were not that difficult
What is a diffraction slot by the way?:(
 

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diyaudio

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Normally the highs beam too much, so, to widen the directivity so that it fills the waveguide a diffraction slot is used, it suddenly expands space of the tweeter. Problem is, the sudden space expansion provides a big acoustic impedance mismatch that causes reflections from the slot and the driver diaphragm. This smears the sound.

The slot is very popular in pro audio.

Conical waveguides donot have the slot.

Very nice TH build. What driver is that? Have you integrated with the system? Do you have measurements?
 

madman29

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Very nice TH build. What driver is that? Have you integrated with the system? Do you have measurements?
Eminence DEFINIMAX™ 4015LF.
No I don't have any measurements. But this subwoofer project was very satisfactory as it can produce huge amount of bass without any distortion effortlessly. It is very different than those mass market SVS or Polk subs.
 

madman29

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Congratulations on your build. Would love to listen to them.
Thank you Saikat. And you're welcome for a demo:)

One change I'm thinking of is to change the local port pipes to good quality Jantzen Audio port pipes. In the process make them a little longer and see how it affects the sq.

After listening to Calpamos for almost 6 months those are my thoughts and understanding

1. First thing that I noticed that break-in period for any speaker which will be used for DIY projects is a must. The Faital Pro mid woofer have opened up considerably and sounds more detailed in the mid and lower mid sound. Previously I used a Focal Chorus floor stander which I remember sounded just fine out of the box and did not change in SQ as much as those Faital Pro mid-woofers did. I guess ready made speakers go through a burn-in process in the factory itself.

2. As I could not afford the original crossover, as supplied by Humble home made hifi (HHH) site, I used the DBX 234XS crossover instead. Now I guess the passive crossover that HHH made for the Calpamos did something more than just dividing the frequency at a given point. It has also made some correction in some frequency which can't be achieved by an active crossover.
Here I am open for suggestion as what I should use to make those corrections. First thing that comes to my mind is an equalizer. Though average equalizer ruins the sound more than make some positive output.
Schiit Loki might be a thing I should be looking for? or something else??

3. High current amplification - this is one thing that baffles me most - is very much needed. The mid-woofer driver that I'm using have 98 db sensitivity and still it is sounding much better with a high current 600w per channel power amplifier (QSC 2450a) than my NAD 2100 power amps feeding them 110w per channel. I can't figure out why more power is needed for such an efficient driver. Though with the QSC it just blows my socks off:oops:

4. SQ wise I will never be able to go back to a speaker with a 6.5 in mid-woofer. This speaker that I built might not be the most articulate in sound- reproduction wise but that thing is much overshadowed by the scale and headroom. It has a quality that goes towards the live sound arena. Though I constantly feel that some amount of frequency shaping will really make those shine. I'm open to suggestions here:)

Will come back with more thoughts as the start popping. Any suggestion is welcome. Thanks a ton for reading:)

I'll try to find the specific kind of foam you suggested.
Do you think a little use of EQ to shape the sound will be helpful? As the original crossover which I could not afford to buy for the high price had some amount of frequency shaping component built into it.

Right now I am looking at two possible choices for EQ
1. Pro audio like BSS or dbx
2 Schiit Loki ( so called audiophile EQ with only 4 Bands)

How do one introduce the 'BBC dip' in the SQ if using only a 2 way electronic crossover?

Though I have seen in the past, any EQ does more harm to the SQ than do good. EQ used in the past are Sony and Technics. Both model were from 90's stacked systems.
 

diyaudio

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1) You have started getting used to the speakers now.
2) Use minidsp for any EQ
3) If both amps are in thier linear region and with plenty of headroom left then they must sound alike. If they dont sound alike, it means that they dont have the same crossover distortion. It is this that gives the amp the sonic signature. At any day I will believe that your QSC is better performer than the other high end stuff. The former means business so has to deliver and is built to deliver no nonsense performance.
4) Pro audio drivers have high dynamics which is what you are enjoying.

Overall, you seem to have achieved very good results. Now if you want to better it more then put 30PPI foam in the diffraction slot. The reflections will make the highs harsh. Once treated, it will be virtually indistinguishable from a high end dome tweeter.
 

madman29

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Update...
Bought QSC 2450A amplifier to drive the mid-woofer of Calpamos. Bass now goes a little lower than it used to with the NAD 2100 power amplifier. Overall the sound have changed for the better.
@diyaudio
Do you want me to stuff the slot with foam. Wouldn't it stop the high from coming out of the horn? Or should I just lightly fill it?
 

diyaudio

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Update...
Bought QSC 2450A amplifier to drive the mid-woofer of Calpamos. Bass now goes a little lower than it used to with the NAD 2100 power amplifier. Overall the sound have changed for the better.
Thats why I say, Pro audio stuff is no nonsense. Somehow folks 'feel' that boutique brands and drivers are better but thats not true.

Do you want me to stuff the slot with foam. Wouldn't it stop the high from coming out of the horn? Or should I just lightly fill it?

Ni, if its normal foam. Yes its 30 PPI foam, only this will work. This foam is open cell foam, it is used for protection in speaker grills in pro audio use and also to protect fans from dust in pro audio amps. You should be able to find it. If you dont find that foam then dont do it, anything else will not work.
 
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madman29

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I'll try to find the specific kind of foam you suggested.
Do you think a little use of EQ to shape the sound will be helpful? As the original crossover which I could not afford to buy for the high price had some amount of frequency shaping component built into it.

Right now I am looking at two possible choices for EQ
1. Pro audio like BSS or dbx
2 Schiit Loki ( so called audiophile EQ with only 4 Bands)

How do one introduce the 'BBC dip' in the SQ if using only a 2 way electronic crossover?

Though I have seen in the past, any EQ does more harm to the SQ than do good. EQ used in the past are Sony and Technics. Both model were from 90's stacked systems.
Did some net hunt for a good EQ. One name that came up repeatedly was KLARK TEKNIK.
Any one in this forum have first hand knowledge about this brand?

Edit:
It's been 4 months. After much thought for an equalizer I decided to replace the dbx crossover 234xs with dbx Driverack 260. This will give me more flexibility to tune the sound as it has some GEQ and PEQ built-in.
 
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madman29

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Well after 6 months I finally changed (added) something in the chain.

I bought an Equalizer:)

Klark Teknik DN 360 from Japan. The main reason for doing this is to shape the high frequencies which can't be done by the electronic XO. Right now in the process of fine tuning it. Without proper measurement this is proving to be a difficult task. Also looking for help from someone with sine wave sweeps and RTA. Any suggestion in this regard is welcome.

As for the EQ it is better than the few I have used before - from Technics and Sony. First thing that I observed, that it does not restrict the dynamic range in any way. Secondly if used in moderation the sound stage stays intact, which is a huge thumbs up for an EQ.

There were other more audiophile EQs out there but sadly not within my budget. And a parametric EQ is too complicated to operate.

Thanks for reading:)
 

diyaudio

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You should replace the DBX with a digital speaker processor. It can do both xover+EQ.
 

yogibear

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This thread is lying dormant for a long time as I was too lazy to upload the picture of the speaker after the project was over.
So here it is
Whats that massive build in the corner ? A sub ?
 

madman29

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Whats that massive build in the corner ? A sub ?
Yes it is a folded horn sub with an Eminence 15" driver. The design is called Tham15. You can google it.
This is the only speaker project that went smoothly from start to finish. And the SQ without any tweaking is wonderful.
Highly recommended project from me. Once you listen to the effortless bass of this sub you could never go back to a home theater sub.
 

sud98

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That Tham subwoofer looks awesome. Does it really go below 10 as per the specs in diyaudio forum? Can you open a separate thread on that so that I dont go OT on this thread.
 

madman29

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That Tham subwoofer looks awesome. Does it really go below 10 as per the specs in diyaudio forum? Can you open a separate thread on that so that I dont go OT on this thread.
This is a good idea. I will try to find the construction pics.
I don't know about 'below 10hz' as I have no way of measuring it, but it never gets over powered. I have heard the first few scene if Specter (the carnival scene) in good movie theater volume and I was not disappointed a bit. The bass background was reproduced in thunderous power.
 
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