Home theater with CHP70 Gen1

SpirosZ

Member
2013-01-18 11:27 am
After abandoning the FAST system with ff85wk + woofer for cost reasons, I decided to try the CHP70 gen1 to build my HT system.
For now I will be using the Arcam Xeta2 3channel surround processor with the Naim Nait 3 powering the front channels. Two 10" Peerless XLS 830452 subwoofers will also be used to cover the low end and relieve the tiny full range drivers from low frequency stress. Amplification of the subs has not being decided yet.
One pair CHP70s and one XLS sub have being purchased for testing since I have never heard them before.
As soon as I test them and approve their sound I will proceed to my plans.
However I truly believe in those little drivers so I will start developing my plan even before I finish with the evaluation process.
My plan is to build 5 speakers using twin CHP70 drivers in each speaker to increase SPL and bring the load to 8 ohms which will be an easier load for a typical AV receiver.
Both the Naim and the Arcam I will be using now can handle easily the 4ohm load of the 4" full-range drivers but at some point they are both going to be replaced with an AV amplifier for convenience reasons and most of them are not very happy driving 4ohm speakers.

The speakers have not arrive yet and right now I am still in the process of choosing the enclosure design for them.
I want the main speakers to sound good in music too and the center channel to match them perfectly.
The subs will most likely handle everything under 100hz so low bass performance is not so important. However I would like them to be able to sound good all the way down to their Fs point.
Since the speakers are going to be in the living room they will also have to look good and they will have to stay close to the rear wall (probably around 30cm from the rear wall max) I want them to stand tall with the drivers between 80-110cm from the ground. The speakers themselves can be as tall as they like.
The subwoofers will be in a very small 17lt box. They can be sealed, ported or with PR. They are very flexible and I will decide after testing them.
They will probably sit next to the main speakers or right under them if the chosen main speakers enclosures are not too tall.
The subs will be in boxes measuring at least 33X33X26cm on the outside, side, front or down firing. The final dimensions will depend on the main speakers enclosure choice as I would like the subs to match their width.

I have seen almost all the enclosure designs available and even though I have already chosen a couple as my favorites I have no idea how they will sound.
I expect to get some feedback on this here.
Also some of them are designed for the CHP70 Gen2 or 3 or the EL70 or the CHR70 and I don't even know if the CHP70s will work in there.
Also the center channel will have to be a modified design as none of the current designs fits the bill.
The surrounds will probably be the dipoles in the aperiodic enclosure. The original plan is not for the CHP70s but I guess they will be fine in there.

My favorite design for the L/R speakers is the slim Wessex (thanks Scottmoose) sitting on top of the side firing subwoofers to bring the drivers at approximately 110cm from the ground or the wide Wessex siting on top of the front or down firing subs and the drivers at 100-110cm from the ground.
If it's not a good idea to sit the mains on top of the subs I can live with the slim Wessex and slim sub enclosures side by side.
I am also considering the Mini Towers, the PensilP70 and even the Coniston.
Actually I even consider using the Coniston as a center channel speaker placed horizontally above the TV.
The only conflict till now is that I want the center channel speaker to also have twin vertical drivers and I don't know if the Coniston (or any other design) can accommodate them. I have a plan in my head but I will probably have to ask the designer's opinion.
What I would like now is some feedback about the available speaker enclosures and my choices in particular, preferably from people that have listen to them and had a first hand experience.
Of course everyone is welcome to comment and share their thoughts about my plans.
I am also going to try using a pair of tweeters crossed above 5k and facing upwards to see if they bring some air in the sound (I have a pair of sweet sounding inverted dome Focal tweeters).
I would also like my system to be able to hit 100db peak at 3 meters all the way down to 30Hz at least. Do you think it is possible?


One more important information. The room is 17sqm with rigid walls, floor and ceiling except the wall behind the speakers which is plasterboard in the middle (2,2X2,2m).
 
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Regardless of the final complement of equipment, 100dB SPL at 30Hz? in a 17m^2 ( 182ft^2) room?

Will there be seating for more than one by the time you get the acoustic treatments in place to achieve those acoustic results? ;)

and you might be surprised to find just how "rigid" the walls really are.

In other words, I'd be inclined to target for more modest performance goals.
 

SpirosZ

Member
2013-01-18 11:27 am
Chris, I mentioned the rigid walls (thick plastered brick walls) because they do not absorb low frequencies like wood or plasterboard walls do and you get really easy boomy sound.
Right now I am trying an amazing pair of Greek brand Audio Spectrum Artemis TLS, 115cm tall 2,5 way floorstanders with twin 6.5" midwoofers (MTM), Top midbass in a BR sub-cabinet and the other one in a TL and they sound great as soon as you take them at least 1.2m away from walls. They have great output even below 30Hz but they are way too big and plain wrong in my room. They are meant to be used in rooms >30sqm and away from walls.
I would like to get similar results with speakers that will be happy to stay close to the rear wall.
I haven't measure the room yet (I plan to do that) but I don't think 100db @30Hz is too much. I know that the subs I chose can reach those levels.
However I will be happy even if I can get 100db at 40Hz as soon as I have reasonably flat response from there up.
 
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I'd port the sub if you want 100db output and don't care about <30hz. But then you'll want to high pass the sub below tuning. I don't see a problem with a 100db from that sub near tuning, but that might be a lot to ask for above tuning. And you won't have a flat response unless you get very lucky. You should think about adding another sub.

I don't the the chp70 will do 100db even at 1m. Well, not cleanly. But it'll be close. Definitely not at 3m. So you'll have maybe 93db at your seat. That should be enjoyable if the speakers can do it cleanly.
 

SpirosZ

Member
2013-01-18 11:27 am
The plan is to have 2X CHP70 and one XLS10 per speaker for L/R and 2 CHP70 for the center and (dipole) surrounds. I expect the CHP70s to be able to handle 30W RMS when they are crossed at 100HZ and that means 15db above their sensitivity rating at 1W/1 meter.
I don't know if sensitivity is measured for a single drive unit or a pair but if it is measured for a single driver, CHP70 has sensitivity of 86.5db at one meter so 4 (2X 2speakers) should be able to produce 92.5 with 1W at 1meter distance.
Am I missing something?
 
Hmm, according to the published Fs, Qes, Vas specs I have, the box loading sensitivity is 86.55 dB, so being nominally 4 ohms I assume these two will be wired in series, ergo sensitivity will not change. A stereo pair will add ~ +3 dB on average, so designing based on 89.56 dB/W/m plus a 6 dB loss/doubling of distance is the safe way to go.

GM
 
I was thinking more along the lines of 100db per channel. Didnt realize you're doing 2 drivers per channel. I'd save the money personally. I don't understand the advantage here. Unless you're rolling one off for baffle step compensation.

If you aren't compensating for baffle losses, there's a few db in the lower mid upper bass you won't have.

I just don't think these full rangers can do HT with much impact. I like full range drivers a lot; for what they can do. I think you'll enjoy your system a lot. I just want to offer realistic expectations. I would even suggest saving your money on the second driver.
 

SpirosZ

Member
2013-01-18 11:27 am
Hmm, according to the published Fs, Qes, Vas specs I have, the box loading sensitivity is 86.55 dB, so being nominally 4 ohms I assume these two will be wired in series, ergo sensitivity will not change. A stereo pair will add ~ +3 dB on average, so designing based on 89.56 dB/W/m plus a 6 dB loss/doubling of distance is the safe way to go.

GM

That would be the case if the amplifier was the limit. However in this case it is the speakers power handling that set the limit. So with one speaker we can only use 30W but with two we can use 60W (30W/driver).
Isn't that right?
 
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SpirosZ

Member
2013-01-18 11:27 am
I was thinking more along the lines of 100db per channel. Didnt realize you're doing 2 drivers per channel. I'd save the money personally. I don't understand the advantage here. Unless you're rolling one off for baffle step compensation.

If you aren't compensating for baffle losses, there's a few db in the lower mid upper bass you won't have.
I was hoping to avoid that but I wouldn't mind doing it if it was necessary.
 

SpirosZ

Member
2013-01-18 11:27 am
All these are just plans in my head.
The idea about the 2 drivers/channel came from the 4ohm resistance and my intention to use a Pioneer AV receiver with a minimum handling of 6ohms.
It sounded also like a good idea to increase SPL (as it became quickly apparent that these speakers will not deliver high SPL).
The whole Idea about the full range speakers came from the great reviews around the net and the simplicity of the design due to the absence of a crossover network.
My main goal was to make an HT system that would use the exact same drivers for all 5 channels.
In my experience that is the most important thing in a good sounding HT system (and a couple of good subwoofers)
I also wanted to avoid the problematic horizontal MTM arrangement usualy found on center channel speakers.

After I receive the test pair of CHP70 and the XLS10" sub I will be able to tell if these are the speakers for me or not.
 
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That would be the case if the amplifier was the limit. However in this case it is the speakers power handling that set the limit. So with one speaker we can only use 30W but with two we can use 60W (30W/driver).
Isn't that right?

True, but has nothing to do with what I posted. I said nothing about the system's limit other than how to calculate the SPL at the listening position [LP] at 1 W/2.83 V sensitivity for a stereo app.

If it turns out that more power is required to meet the performance goals than the amp and/or the speakers can handle at low distortion, then either more power and/or drivers per channel are required or a different system design with more efficient drivers.

GM
 

SpirosZ

Member
2013-01-18 11:27 am
Right now I have a pair of Naim IBLs, a pair of Greek brand (unknown to most folks here but really good speakers) Roister Silk 100 (8" Vifa woofer and silk dome Vifa tweeter, amazing value for money speakers) and also an outstanding pair of Audio Spectrum Artemis TLS, tall 2.5 way floorstanders also from a Greek manufacturer (that one is borrowed). The Naim needs a pair of high quality, fast subwoofers and it will be fine. The Roister speakers sound great as they are and the Artemis are just too big for my room. None of them has a matching center speaker or surrounds. If I could find something that matches any one of them I wouldn't be here right now.
In the end I may discover that nothing works and end up buying a set of Polk TL3s or something similar and be done with it but I was hoping to get something much better for just a little bit more money going DIY.
 
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I'm not trying to scare you away from DIY, just have the proper expectation, don't waste money, and build what meets your expectations.

For me, my expectations for HT are about 100db per channel and the listening position, CLEAN and CLEAR! Relatively flat anechoic frequency response. Relatively smooth down sloping frequency response at the seating position. Smooth bass down into low teens and even single hz. So I'm building my system to meet those expectations. It's taking me a long time. You should start with expectations, buy critical components to get you on your way, and add as you go.

That means I'd only go with 1 driver per channel right now. Add the FAST woofers later. Add more subs later. Etc. You say you don't want the problems of an MTM center, but that's exactly what 2 full rangers will give you.
 

SpirosZ

Member
2013-01-18 11:27 am
You should start with expectations, buy critical components to get you on your way, and add as you go.
That's why I will wait till my first pair of CHP70s and the XLS sub arrives and gets tested.

You say you don't want the problems of an MTM center, but that's exactly what 2 full rangers will give you.
I was planning to place them Vertically and not Horizontally. The front panel would have to be 26cm tall but it's a fair compromise.

Anyway thanks for the contribution, it's helping me make my plans.
We'll see. I don't think my expectations are difficult to meet. I only need to make the right decisions.