Joe
pfm Member
Cost difference £4350 - If I was buying £11k speakers I'd expect to spend a similar amount on an amplifier.
Eek!!!....I drive my SCM 50's with a pair of DIY ncc200 amps that cost £500 the pair. What should I do ?
Cost difference £4350 - If I was buying £11k speakers I'd expect to spend a similar amount on an amplifier.
Eek!!!....I drive my SCM 50's with a pair of DIY ncc200 amps that cost £500 the pair. What should I do ?
Put them in a £10.5k case!
Buy a fire extinguisher?Eek!!!....I drive my SCM 50's with a pair of DIY ncc200 amps that cost £500 the pair. What should I do ?
This is a quick theoretical sum to compare system gains in terms of dB SPL output for 1 V input from the preamp:SCM40A is what my intended upgrade is. Currently I have passive 19s, with Quad 909 and EAR 868PL preamp.
As 868 is pretty much my dream preamp (used 864 for a long time before it) with incredible phono stage (TT is my primary source).
The only thing I can't figure out regarding compatibility of 868 and power modules in SCM40A is whether gain I'm going to have is going to be higher or smaller than now with quad 909 and SCM19. I wouldn't want more gain.
868 has output impedance of 600ohms. It has max output voltage of 5V.
909 has input sensitivity of 0.775V
Power amps in 40A have input sensitivity of 1V.
Sensitivity of both SCM19 passive and SCM40 (this rating is stated only for the passive version on ATC's site) is 85dB.
Am I right in thinking that the 868/SCM40A should have a bit lower gain than 868/909/SCM19?
Has anyone tried EAR 868 with active 40s and what was the resukt gain-wise?
I've an unqualified suspicion that a larger drive unit might work better in this application, one that uses some cone mechanics to reduce the radiating area as frequency rises. Or he needs to add a high pass function to the 'crossover'. Or perhaps just delete the port. Not a speaker designer...I have heard some tiny “full-range” single-drivers I’ve liked a lot, e.g. 47 Labs, plus bigger things like Frugal Horns, some Lowthers etc. I could imagine a pair of really nice small single driver speakers of this genre being great on a desktop either side of a computer monitor and I suspect I’d prefer that point-source presentation to a small two-way at that listening distance.
PS The thing that puts me off about these is they have passive crossover components. Much of the attraction to my mind of the single driver mindset is the life and dynamic subtlety that comes from getting rid of crossovers from the equation entirely. I’d likely prefer a point-source two-way such as an LS50 or small Tannoy if I had to have passive response shaping. To put it another way if I was designing that speaker I’d have picked a better single driver!
This is a quick theoretical sum to compare system gains in terms of dB SPL output for 1 V input from the preamp:
Quad 909: 0.775 V sensitivity for (I assume) maximum specified output of 140 W / 8 Ohms => gain = 32.7 dB
SCM19: 85 dB SPL for 1 W / 8 Ohms (2.83 V) => 76 dB SPL for 1 V input (i.e. 9 dB less)
Quad 909 + SCM19: 32.7 + 76 => 109 dB SPL for 1 V input.
SCM40A: 1 V sensitivity for (I assume) maximum specified output of 112 dB SPL => 112 dB SPL for 1 V input.
There are some assumptions above about what "sensitivity" means exactly. Perhaps someone can sanity check these sums.
It looks (if I have the figures, assumptions and sums right) like the SCM40A has just over 3 dB more gain rather than less.
If so, the volume control on the EAR 868 will have to sit a little lower for the same volume level with the SCM40A. That 3 dB difference is equivalent to between quarter of an hour and half an hour lower with a normal audio potentiometer in about the 09:00 position, but I don't know what the EAR 868 has. However unless the volume control knob is very low right now it is probably not an issue.
The principle was to look at the Quad 909 + passive SCM19 as a complete system and work out how to compare that system with the most direct equivalent specification for the SCM40A.John, thank you very much for such a detailed and quality reply.
The only thing I don't understand is why you took the sensitivity rating of SCM19 as 85 dB SPL for 1 W / 8 Ohms (which is what ATC states), but for 40A you took maximum rating of 112dB SPL (while SCM40 passive is also rated as 85 dB SPL for 1 W / 8 Ohms). ...
compatibility of 868 and power modules in SCM40A
Has anyone tried EAR 868 with active 40s and what was the resukt gain-wise?
The extant Quad has more gain that that implied for the active ATCs by my experience. So after upgrade volume will need turning up and this is a good thing.It looks like @Paul R comes to a different conclusion to mine but I don't understand his last sentence at least: if an amplifier has a higher gain you need to turn the volume knob down to get the same volume. I will take a more careful look to see what it is I misunderstand.