About pro drivers in hi-fi for 20-20khz project

[oaristys]

F3 is the frequency where the response is -3dB relative to the nominal sensitivity.

OK thank's 🙂

 

[Brett]

Can u learn me something 🙂 ?

I always calculate the SPL with dp 1w 1m. But sometime, i see f3 or other "f" value. What does it meen ?


And please gentleman, don't use abbreviation because i'm french and i don't understand it :s

Thank's and i appreciate your help !

As 454 has stated F3 is the frequency where the response has fallen by 3dB or half power. F6 and F10 are also sometimes used and these are -6 and -10dB respectively.

and what is the difference between 1w 1m and 2.8v/1m

Speakers vary in impedance, both in the nominal rating of the speaker, ie it's a 4 ohm or 8 ohm speaker, and also each speaker will vary a lot in impedance at different frequencies.

2.83V is 1W across an 8 ohm resistor so is a constant and the real sensitivity can be calculated if the impedance is known, at least the nominal impedance.

Lots of companies play games with the sensitivity figures and just give a number like 88dB or 92dB which can be misleading. For example, the Proac you mentioned says 92dB/W/m. As it is a 4 ohm speaker, that would mean that the voltage across it's terminals was 2V, which is 1W into 4 ohms.

They could have been slightly misleading and stated it is 95dB/2.83V/1m which non technical readers might think meant the speaker is more sensitive than another. But 2.83V across 4 ohms is 2W, not 1W.

Wow, the ProAc D100 is 92db 1w 1m sensitive with response 20-20000hz !!!


Hoffman where are you !?

Still present. That is not exactly a small speaker.

 

[oaristys]

Still present. That is not exactly a small speaker. [/B]

So i think i can answer to the original post question. "Yes, the quality of the driver is important and will affect the result"

The ProAc do good efficiency with good bass and with a deep bass output. The volume is about 8 cu feet if my memory is good. I can't do 25hz at 89db with mtm configuration with less than 75$ drivers in this volume range. All the DIY project i found is for bigger enclosure, less efficiency, more xpensive driver or all of this.

...

 

[Brett]

So i think i can answer to the original post question. "Yes, the quality of the driver is important and will affect the result"

The use of quality drive units as a basis for a qua;ity speaker was never a question in my mind.

The ProAc do good efficiency with good bass and with a deep bass output. The volume is about 8 cu feet if my memory is good. I can't do 25hz at 89db with mtm configuration with less than 75$ drivers in this volume range. All the DIY project i found is for bigger enclosure, less efficiency, more xpensive driver or all of this.

...

The UK prices I've googled for the Proacs are in the order of UKP15-16000 and there are few DIY speakers that hit that sort of expense level, an amount I hardly see you spending when you thought the AE was expensive compared to a Selenium. I also doubt you are going to get anywhere near the quality of the Proac in an MTM for $75 especially as the ATC mids retail for about UKP350 ea.

Proac spec for an FR to 20Hz, but give no +/-dB. The surrounds on the LF drivers look like they might be good for 6mm or so, so they may well do 20Hz, just not very loud.

I can't see a way to achieve what you want; 20-20k in a reasonable, if large box (say <300L) with highish efficiency and cheap drivers. Especially as you want to use a single tube amp for whatever reason.