Hmm, that's a tough call. How do I decide now...
To put things into perspective, let me ask this: will two 16 ohm drivers in parallel (8 ohm effectively) have lower volume than a single 8 ohm driver at the same voltage?
Hard to say because the specifications are not clear. It says Sensitivity 1w/1m but sensitivity, by definition is 2.83 V in:
if 1w/1m (simple math P=v^2/R -> V =sqrt(pxR) assume 8 and 16Ω) someone please check my math
16Ω 3FE25 90 dB 4V in, add a 2nd driver, you get 6 dB more, helf due to doubling the number of drivers, half from double the power in, ie 96 dB, 2W in, 93 dB, 1 w in.
if sensitivity, then ½w in gives 90 dB, double th edrivers gives 3 dB, twice the power gives 96 dB 1 w
8Ω FaitalPro 3FE25 91 dB, 2.83 V in is 1 w so 1 driver is 91 dB 1 w in both scenarios.
dave
if 1w/1m (simple math P=v^2/R -> V =sqrt(pxR) assume 8 and 16Ω) someone please check my math
16Ω 3FE25 90 dB 4V in, add a 2nd driver, you get 6 dB more, helf due to doubling the number of drivers, half from double the power in, ie 96 dB, 2W in, 93 dB, 1 w in.
if sensitivity, then ½w in gives 90 dB, double th edrivers gives 3 dB, twice the power gives 96 dB 1 w
8Ω FaitalPro 3FE25 91 dB, 2.83 V in is 1 w so 1 driver is 91 dB 1 w in both scenarios.
dave
Thanks Dave. Even if it's just 93dB @ 1W, it's still quite a bit more volume as one driver. To me that means I should be ok with two 16Ω drivers, without fear that the the ACA's won't be able to drive it to sufficient volume.
I hope my reasoning is realistic.
Christo
There is one big difference between 4ohm and 8ohm speakers: the 4ohm ones let you extract twice the power from the ACA for the same voltage drive level.
ACA is a nominal 5w amp into 8ohms. That means it can drive 6.32v rms into 8ohms. That same 6.32v rms into 4ohms draws twice the current and it is now a nominal 10w amp. Probably distortion climbs if you try pushing that much more current from it, but nice to know the capability of there for more dynamic transients. I wouldn't worry about hurting your ACA. At worst you blow a common $1.75 IRFP240 MOSFET. I have yet to blow one from overdriving it (and I have used over 3 dozen of them in all my amps). I lost a few from thermal runaway on a Class AB where the temp comp wasn't working right - and that happens almost instantaneously.
ACA is a nominal 5w amp into 8ohms. That means it can drive 6.32v rms into 8ohms. That same 6.32v rms into 4ohms draws twice the current and it is now a nominal 10w amp. Probably distortion climbs if you try pushing that much more current from it, but nice to know the capability of there for more dynamic transients. I wouldn't worry about hurting your ACA. At worst you blow a common $1.75 IRFP240 MOSFET. I have yet to blow one from overdriving it (and I have used over 3 dozen of them in all my amps). I lost a few from thermal runaway on a Class AB where the temp comp wasn't working right - and that happens almost instantaneously.
Thanks X. Part of the reason that I've decided on Karlsonators is that I've heard how good the 0.40x sounds. Twocents built a set from foam board and I was blown away by the excellent sound of such small speakers.
Thank you for all the hard work testing and promoting the design.
Some feedback: This afternoon I received four 3FE25-16's for my dual driver 0.53x Karlsonator build. I ended up having to import the drivers from a shop in Italy (cheapest option) because two local suppliers couldn't get them for me. Apparently, there is a minimum order quantity of 36 from the factory.
Anyway, I have another question about speakers for the ACA's.
X posted the following in the Mini Karlsonator (0.53X) with Dual TC9FD's thread:
Anyway, I have another question about speakers for the ACA's.
X posted the following in the Mini Karlsonator (0.53X) with Dual TC9FD's thread:
“For anyone wanting to try a more HiFi upgraded sound with deeper bass, very smooth mids and clear highs, I can recommend the Tang Band W5-2143 in an XKi. I think it should work in a Karlsonator as well but the box is a good size due to the larger Vas. Great sounding driver though.”
Would these be suitable speakers for a pair of ACA’s? I’m considering building a second sound system for my office consisting of B1 + ACA's and I’ll need speakers. The idea is to use the 0.53x Karlsonators with dual 3FE25's in my office and then build bigger speakers for the lounge/listening area.
Let me hook up my ACA to my XKi fitted with W5-2143 and let you know what I think. Personally, I think you might want an amp with more oomph than 5w bit then I don't know what kind of levels of dynamics you are used to listening to. I had the dmm hooked up while playing from a larger Babelfish J amp and to get the SPL levels I like, it was routinely hitting 4.5 to 5v rms. That certainly is within range of ACA but 5v rms is about 14v peak-peak. Can ACA do that comfortably?
To get the ACA to put out 14v requires a preamp capable of hitting 1.4v p-p so a cellphone isn't going to be able to do that. Will need a real preamp.
To get the ACA to put out 14v requires a preamp capable of hitting 1.4v p-p so a cellphone isn't going to be able to do that. Will need a real preamp.
Skylar,
Just got a chance to test ACA with XKi fitted with W5-2143. Works exceedingly well. Nice deep bass, very smooth wonderful sounding. Almost like a match made in Class A heaven. Decent SPL's - I used headphone out from CD player as source so sort of like a real preamp with good juice. I can highly recommend this pairing.
X
Just got a chance to test ACA with XKi fitted with W5-2143. Works exceedingly well. Nice deep bass, very smooth wonderful sounding. Almost like a match made in Class A heaven. Decent SPL's - I used headphone out from CD player as source so sort of like a real preamp with good juice. I can highly recommend this pairing.
X
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