I read Nelson’s 2004 article on current source amps, but both the speakers and the amps have changed since then. What is the short list of First Watt amps for these speakers? I am open to commercial First Watt amps.
I am going to try an SLOB, still figuring out the bass unit, with a PAP. I have some 21” B&C drivers, but they might be a bit garish and have too much moving mass, for this project.
I am going to try an SLOB, still figuring out the bass unit, with a PAP. I have some 21” B&C drivers, but they might be a bit garish and have too much moving mass, for this project.
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Impedance-wise, if you go with a current source and the PM6a, you will get bass overload, a very linear midrange and lower treble response, and a tiny bit of extra treble at the top.
With a voltage source, given a low source impedance/high damping factor, I would expect thinner bass and a db loss in those octaves, a similar midrange to a current source, but a small level drop in the top octave(s). With a bit higher source impedance, for example from a tube amp or a transistor amp with this «quality», you may find the bass perfect.
Solving this will, as you know from reading Pa’s toilet litterature, differ entirely from current to voltage source.
with a current source, decrease source impedance until you are happy with the bass. For mid/treble adjustments, consider a network iaw Pa’s article/own measurements,
With a voltage source, increase source impedance until you are happy, for mids and treble - same procedure as current source.
You can basically make any amp work with these drivers. But some will have better intrinsic performance than others.
You need F1 boards, ask Peppenino.
You need F2 boards, ask Twitchie.
Wanna make a SIT? Ask Zen Mod
🙂
Edited to add: I found this: http://www.loudspeakerdatabase.com/Lowther/PM6A
The blue line pretty much sums up expected frequency response with a typical voltage source.
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I have a pair of Lowther pm2a's currently in my main system. I've used my M2x, ALEPH J, Singing Bush SiT, P channel VFET and an N channel VFET to drive them with no problem. 25w, 10w and the Singing Bush is around 35w, no need for any more power. Each amp is a little different, the soundstage the Lowther's produce is 3d.
Matching the preamp to the amp makes a bigger difference, so think system not components.
Matching the preamp to the amp makes a bigger difference, so think system not components.
That was meant as a joke.
Seriously, build F4 and use various preamps till you find the perfect one to suit your taste. Like B1 NuTube.
Well, it certainly meets the “system” requirements!
Given its lack of input sensitivity does the F4 preclude the use of the Lowther in a bi-amp set up, or are there crossovers that put out enough voltage to drive it?
No. The B1K for example, will drive the F4 more than good enough for your lowthers.
My Alpairs with a similar sensitivity, need only 1-1,5 watts to sing loud enough to not wanna crank it any further in my room.
How can a crossover put out extra voltage unless active with gain? Or an autoformer… making it as much a preamp as a crossover.🎅
Yup, I have spare F1 boards. If you don't need 10W, I'd probably go for F2 for Lowther.
[EDIT] Power output referred to 8 Ohm
As Papa said, F1 and F2 are "well suited to sensitive full-range drivers such as Lowther or Fostex, and allows easy use of parallel loading networks to tailor the driver response.
While the F1 has a crisp sounding 3rd harmonic signature, the F2 has a richer pure 2nd harmonic character, and this difference is the primary justification for offering a second no-feedback current source amplifier."
https://www.firstwatt.com/f1.html
https://www.firstwatt.com/f2.html
While the F1 has a crisp sounding 3rd harmonic signature, the F2 has a richer pure 2nd harmonic character, and this difference is the primary justification for offering a second no-feedback current source amplifier."
https://www.firstwatt.com/f1.html
https://www.firstwatt.com/f2.html
I am wondering if the amp can work with a preamp and an electronic crossover, with enough voltage out. I am didn’t suggest a crossover with gain, but I am not aware of all the options, etc.
