I would have to reread the article to pin point that. IIRC, 70 into 8 ohms, most all of that within the class A envelope. The most stunning part is the square law output stage. No source resistors. It thrashes speakers with iron glove control, but still warm, transparent and wide and deep image. Rock stable. Best I've had so far!
I think I’m being a bit dim - is there a kit available then? It’s not jumping out at me! And which iteration did you build?
Cheers,
David
I’ll take a dive into the thread. It looks a bit “techie” from what I’ve seen so far. I can follow instructions and solder reasonably neatly, but my brain struggles without clarity. I’ll put my big boy pants on..
Of the three amps, what’s the rough difference? I’m assuming you’ve chosen the one best suited to the XSD!
Thanks again for the encouragement!
Of the three amps, what’s the rough difference? I’m assuming you’ve chosen the one best suited to the XSD!
Thanks again for the encouragement!
Note that the XSD benefits from a 4ohm capable amp and I would suggest at least 100w of power. If you can get 150w to 300w, even better for the high dynamics this speaker is capable of. Because of the high sensitivity, even 25w amps can work but you will not be able to experience the deep bass dynamics which take power to move that much air. Look at it as a speaker with dual 12in woofers in an open baffle and ask yourself what kind of an amp you would use for that.
Cwlo is also using the same combo. He seems quite pleased with the pairing. BA3 drove it quite well, XA252 seems to really whip them up. Do build it dual mono...although factory X25 uses only one, normally I do too....not with this one. I
Expect more amplifiers going forward will utilize this square law output stage method. I think it is a game changer. The actual Pass Labs XA25 is the only commercial amplifier I am aware of that used it. I'm sure the big puck mosfets play a role in the ampsability to keep doubling down with decreasing speaker loads.
Russell
Expect more amplifiers going forward will utilize this square law output stage method. I think it is a game changer. The actual Pass Labs XA25 is the only commercial amplifier I am aware of that used it. I'm sure the big puck mosfets play a role in the ampsability to keep doubling down with decreasing speaker loads.
Russell
Well, I finally cobbled my Frankenstein monster version of the XSD's together and got everything working...sorta. I'm all active using 4 Ayima 07 amps for 8 channels: Tweeter, Mid and two channels for the woofers. I have 4 woofers per channel in a simple parallel pairs in series. Unfortunately, I seem to have 2 bad outputs from my DSP so I'm currently driving both woofers from the left speaker's two woofer outputs of the DSP. I'm using the original 470 and 4700 hz crossover points with 12 db per octave slope on the woofer/mid (470hz) and 24 db per octave at the 4700hz point. Haven't been able to turn up the volume or run test tones yet. The volume levels are WAY different and I have a gain on all 8 channels in order to tweak all the levels, but currently I have the PRV at mx plus 12 db and the planar tweeter at plus 3 but had to attenuate the woofers by -25db for all 4 channels. I thought it was not loud during my first music test this morning but my daughter complained that it was too loud and she could feel her floor vibrating on the floor above, so I had to mute them completely. Further testing to come tonight.
BTW, this seemed like such a simple little build, until I taught myself how to use a router during this...on this project and NOT on practice wood. My wife encouraged me by reminding me that this was a learning experience and a proof of concept test bed, but I HIGHLY recommend the flatpack. I have learned things so not a waste or effort even if it was a waste of time. Will try to tweak amp gains to remove boost from DSP and start listening tests, possibly followed by measurements and additional tweaks.
You really need to measure the response with a calibrated mic in order to set the DSP filters and levels properly. Setting the levels to be balanced is important but the relative delays between the three drivers is almost impossible to set without measurement.
Yup. Got to agree. May be the longest breaking in of any speaker I've broken in!
Hi XRK,
I have often heard "amp should be happy with 4r load", etc. Since most amps, at least the ones we build here on diyaudio can be used for 8r or 4r loads, what parameter should we be looking for to determine an amp's better suitability for 4r loads?
Thanks. Nash
What I took away from his description of amp requirements is the same you would consider for an open baffle 15" pair of woofers.
I have tried 3 amps. First was Aleph J, as it was in the system I was closest to. It drove them, but was short lived and definitely before break in.
Break in occurred mainly with BA3 amp, 31 volt rails and approximately 50 watts. It seemed to do well. With the XA 252, a lot more control and power to bass. I need the balanced version! (yet to be released).
I have tried 3 amps. First was Aleph J, as it was in the system I was closest to. It drove them, but was short lived and definitely before break in.
Break in occurred mainly with BA3 amp, 31 volt rails and approximately 50 watts. It seemed to do well. With the XA 252, a lot more control and power to bass. I need the balanced version! (yet to be released).
Look for high damping factor (DF) preferably at least 50, and ideally DF > 150 in order to have the ability to actuate and control the woofer cone motion with authority.
DF is the speaker impedance divided by the amp's output impedance plus speaker cable impedance. Also, check to make sure amp will not clip at peaks of music at the levels you like to play. Assume you have nice audio tracks with 20dB dynamic range, and you listen at fairly loud average level of 86dB. Peak crescendo will be 106dB. To get 106dB from 92dB speakers (2.83v at 4ohms or 2W) is 12dB increase. That is about 4x x 3dB (doubling) or 16x in power requirements without clipping or 32W peak. So a 50W amp should be able to handle that but a 25W amp cannot. You can scale that up to other levels as needed and distance from speakers. "Center of Dancefloor" volume is about 89dB and speakers will be say 4m away. So that is 2 more doublings (6dB) ad 3dB more for SPL baseline. Or 3 more doublings of 32W - for circa 250W. Power requirements go up pretty quick - but this speaker can indeed handle 250W and you can throw a dance party with them and it will still sound clean.