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Old 15th August 2011, 09:20 PM   #31
ST7677 is offline ST7677  India
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Quote:
Originally Posted by AndrewT View Post
Hi,
Thanks for finally posting the sensitivities of the drivers from your original question.
...
Five amps each of ~68W into 8ohms will result in ~ 300W per channel of active speaker power.
This will probably sound as loud, or louder, than a single 300W amplifier driving a 3way 5driver set up with passive crossover.
I would predict the maximum sinewave SPL from each driver with 68W available as
Treble 107dB
Mid 106dB
Bass 112dB
all +-manufacturing tolerances.
My calculations suggests that in dipole configuration
The woofer driven from 50W amplifier and 7 amp max current will be
XMAX limted at 20 hz
Voltage limited between 20hz to 88hz
Current limited above 88hz
Max freespace SPL at 30hz = 76db
Max freespace SPL at 90hz = 93db


The woofer driven from 130W amplifier and 12 amp max current will be
XMAX limted at 30 hz
Voltage limited above 30hz
Max freespace SPL at 30hz = 80db
Max freespace SPL at 90hz = 98db

Since the woofer is required to work between primarily between 20hz to 92 hz (later being the crossover cutoff to midrange) the second option seems to be the desired configuration.

Ofcourse these are for one woofer in open space. For 4 woofers in a room powered by individual amps, 18db can be added for overall loudness.
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Old 16th August 2011, 12:14 AM   #32
parb is offline parb  United States
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Are you planning on using the new seas speakers in the upcoming 3.4 version?
If so your hunch of having 120watt or so on tap per bass speaker seems like the right one give pm comments ls has made on his forum lately.
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Old 16th August 2011, 10:46 AM   #33
Colin is offline Colin  United Kingdom
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FWIW, the manufacturer of the active speaker I'm currently using recommends an overall headroom of 26dB above normal listening levels to accommodate peaks in orchestral music.

Normal listening levels will vary, of course, and can be 1/4 watt or less.

Another bit of useful info (from Rod Elliot's site) which may be of interest - a passive crossover loses around 3dB. So using 2 x 50 watt amps with a 2-way active speaker will match the output of the passive version driven by a single 200 watt amplifier.

Good luck with the project - you're getting some invaluable advice from the other posters here.
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Old 16th August 2011, 11:16 AM   #34
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26 dB of headroom? So the average listening level of a standard 30 W into 8 Ohm gainclone should not exceed 75 mW?
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Old 16th August 2011, 11:55 AM   #35
Colin is offline Colin  United Kingdom
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Or accept some clipping. We're talking ideal, on orchestral music.
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Old 16th August 2011, 12:40 PM   #36
ST7677 is offline ST7677  India
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Quote:
Originally Posted by parb View Post
Are you planning on using the new seas speakers in the upcoming 3.4 version?
If so your hunch of having 120watt or so on tap per bass speaker seems like the right one give pm comments ls has made on his forum lately.
No I am planning to use the Peerless 830452 and build ver 3.3

In the version 3.4 SL has updated per channel power requirement to 150W, i.e. 150W x 8 channels of active amplification...
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Old 16th August 2011, 01:36 PM   #37
AndrewT is offline AndrewT  Scotland
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Quote:
Originally Posted by pacificblue View Post
26 dB of headroom? So the average listening level of a standard 30 W into 8 Ohm gainclone should not exceed 75 mW?
I generally aim for 20dB of headroom for AC peak to AC average dynamic range.
I regularly use low dynamic range sources (FM radio) that, even at maximum volume, cannot drive the chipamp to clipping.
Yet, from my normal listening levels of <680mW into 8ohm speakers, I can hear deterioration of SQ as average levels approach and go above ~1W into 8ohms, even though I know I am well below voltage clipping of the chipamp.
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Old 16th August 2011, 08:19 PM   #38
Colin is offline Colin  United Kingdom
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Hi Andrew - useful info (as ever). Thanks.
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Old 5th September 2011, 08:32 PM   #39
ST7677 is offline ST7677  India
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Since these are going to be DIY amplifiers and DIY speakers, I am planning to integrate the amplifiers into the speaker cabinate itself for increased WAF i.e. to reduce the space the whole thing will take, + reduction in number of cables for power and interconnection (Only two wires will go into a speaker (+amp) cabinate – one mains power and one source signal wire (RCA)).

The amplifiers and power supply will be separated and put on two different levels respectively (see image).
The amplifiers (8 LM3886s) will be housed in the bottom most part of each speaker cabinate (this is in an extended height area over standard design).
The power supply will be put between the mid range and the woofer speakers, where about 5-6" space is already available.

Orion intergated with amps 1.JPG

Most wires will move within the cabinate, ie. power wires between the Power Supply to ASP / Amplifiers and signal wired between ASP to Amplifiers and then to speakers.

IMO, There are multiple advantages to this approach.
1. Separation of power supply and amplifiers, reducing induction related noises and cleaner sound
2. Short wiring between amplifier and speaker, which means less expense on speaker wires and better amplifier control on speaker (damping effect, due to lower wire resistance).
3. Integrated design, saves space in my small house
4. Clean wiring - only 2 wires will go to each speaker. Else wires will first go to ASP from there 3 wires will go to amplifier from where 5 wires will go to speaker box + power wires to ASP and to Amps
5. No cost of expensive amplifier cases

Disadvantages are
1. All speakers (specially Tweeter and mid range) height moves up by about 5". As per standard Orion design Tweeter should ideally be at 42.5" i.e ear height level while sitting or slightly higher - is this a big issue over 8'+ listening distance
2. Rear wave of mid range may be slightly impacted due to additional box of amp power supply - again is this likely to be significant?
Any other possible issues?

Is there any possibility of amplifier power supply (torroids) interfereing with the speakers (mid range above and woofer below) in anyway (assuming I will keep the signal wires away from power wires)? There are likely to be two 500VA torroids placed together for each side of speaker.

Please share your inputs.

Last edited by ST7677; 5th September 2011 at 08:42 PM.
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Old 5th September 2011, 08:42 PM   #40
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You might consider posting this info on the Orion Support forum to get a reading from SL...I recall that he has previously stated that the Orion geometry should be adhered to within 1/4" (6mm) to maintain SQ.
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