As I am considering some of the amp choices available, I figured that there might be
someone who have already gone through some of the options and have a clear
understanding of the differences.
The first goal is to do an active system and for this reason, I will need a set of amplifiers.
The woofer will be driven by Purifi's class D which leaves me with the need for a
midrange and tweeter amplifier.
25W in 8ohm should be more than sufficient for a tweeter and midrange at less than
100dB listening levels. I am usually 85-90 dB maximum, and class A for its perfect transition.
Neutral, natural and relaxed clarity is the best description I can give. The amp should be able to
deliver lots of air and nice dynamic range without sounding too relaxed or "warm".
Which one of the Aleph J, M2x and F6 can be considered to get me closest to my need and desire ?
Many thanks for any reply.
someone who have already gone through some of the options and have a clear
understanding of the differences.
The first goal is to do an active system and for this reason, I will need a set of amplifiers.
The woofer will be driven by Purifi's class D which leaves me with the need for a
midrange and tweeter amplifier.
25W in 8ohm should be more than sufficient for a tweeter and midrange at less than
100dB listening levels. I am usually 85-90 dB maximum, and class A for its perfect transition.
Neutral, natural and relaxed clarity is the best description I can give. The amp should be able to
deliver lots of air and nice dynamic range without sounding too relaxed or "warm".
Which one of the Aleph J, M2x and F6 can be considered to get me closest to my need and desire ?
Many thanks for any reply.
Yeah, any of those three should meet the general requirements. They all have a slightly different sound, and all sound wonderful.
From my experience, the Aleph J is the easiest to get the best sound. The M2x needs a little help to prevent magnetic coupling from the power transformer to the signal transformers. The F6 is very good as a standard build, but benefits greatly from a few careful modifications.
From my experience, the Aleph J is the easiest to get the best sound. The M2x needs a little help to prevent magnetic coupling from the power transformer to the signal transformers. The F6 is very good as a standard build, but benefits greatly from a few careful modifications.
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Thanks.
I know the most common recommendation is to evaluate all 3 and make up my mind after that so in the end, perhaps I need to do that...
No matter, I'll start with reading the threads and see what the common build methods are
and what people have to say 🙂
I know the most common recommendation is to evaluate all 3 and make up my mind after that so in the end, perhaps I need to do that...
No matter, I'll start with reading the threads and see what the common build methods are
and what people have to say 🙂
Kind of depends on the specs of the speakers
Will you be using active crossovers on the Tweeter and Midrange, or is it a passive crossover?
Will you be using active crossovers on the Tweeter and Midrange, or is it a passive crossover?
Active for all drivers.
DIY Biamp 6-24 Crossover – diyAudio Store
The speakers will be of my own design, starting with a 3-way. Driver spec ranges from 90.3dB/W to 93 dB/W - with the lowest one dictating the neutral level.
90 dB is already a good place since I commonly listen to music between 75-90 dB.
Its the dynamic range of the music program that dictates the current draw so as long
as there is a good headroom, things should be okay. No matter, its the mid-bass and
bellow that demand most of the amplifier(s), hence a few hundred watts for the woofer.
I did notice the 50W in 4ohm which the F6 is capable of. Might not need all 50W for the midrange but headroom come to mind 😀
If they are all 8 Ohm drivers then I would probably go with the Aleph J
Aleph J requires a little beefier hardware do to the higher bias currents.
Aleph J requires a little beefier hardware do to the higher bias currents.
8 ohm means we are looking at probably 87.5-88dB sensitivity.
Does the Aleph J like a higher impedance load compared to F6 and M2x ?
Tweeter is 6 ohm and midrange can be 4 or 8.
Does the Aleph J like a higher impedance load compared to F6 and M2x ?
Tweeter is 6 ohm and midrange can be 4 or 8.
Aleph J was a designed around an 8 Ohm nominal load, it doesn't continue scaling into lower impedance loads cause it current clips.
It will depend on the impedance plot of the driver, if it's 4 Ohms and doesn't fall below 3.5 Ohms you'll be ok, but if it drops to 2.5 Ohms, that would be a little risky using Aleph J.
Decide exactly which drivers you are going to use, then choose the amp based on that, or choose the Aleph J and make sure the drivers are suitable for the Aleph.
Your choice.
Sounds like the M2x or F6 is a safer bet in my case. The M2x has the option of being tunable so kinda like that feature 🙂
F6 wasn't my favorite. Pretty good with simple music. I enjoy my current setup significantly more... (in signature) I would try out the M2x myself, out of the choices you are looking at..
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Lets expand.
I recently took delivery of the new UGS Muses v2 batch, so that will be my preamp. Looking at your setup, you are using the F4 which need a voltage gain preamp which the UGS Muses is, so should be safe there.
"The F4 manual advises balanced monoblocks for 87db or below speakers, with a preamp that can swing 14 volts and 20db gain"
- UGS Muses is about 24V and 20dB gain if my memory serves me right. It is also SE and Bal, so the option of balanced out is there.
Not sure if there exist a bal version of the M2x, have not come that far in my exploration, but F4 in bal can do 100W into 8ohm.
Any experience between the F4 and M2x ?
***
The tweeter is hardly going to demand much, so very easy to drive. Its the midrange that will require most of them two. No matter, 25W should be able to reproduce 100dB with a medium sensitive driver. Say you are listening to 85dB on average with certain passages being almost quiet while short burst of 100dB transients occur, meaning 100% of the output is used and this is putting some serious stress on the amp 🙂
These are the things are am thinking about
If you absolutely love the tone of your preamp then go w the F4. The F4 is hands down my favorite out of all these amps available to build. I gifted my M2x build to my father, the F4 is my main amp while i throw in the AJ from time to time.
I have not heard the M2x. I've always been interested in building one though. I was surprised at how good Wayne's linestage is, and there is something I like about having some signal iron in there. I don't know what it is though... maybe a small amount of "pleasing" distortion without being too warm and gooey??? Just not sure. I use the balanced input option on the BA 2018. So it also serves as my balanced to SE converter. I power it with a killer PS, the Salas designed Ultra-Bib shunt reg and an overkill toroid.
"... However, the F5 in particular is astonishingly clean and fresh." in comparison to the M2 according to 6moons. So, with my particular needs, the F5 and F5 Turbo is closer.
Other comments:
"F5 very fast and detailed, bit dry. F4 more ''Musical'' can sound great with tube preamp." and "My mate built the F5, I've borrowed it a few times, but for me F4 & pumpkin is very hard to beat very musical."
"The F4 is, in a word, better. The main differences I'm hearing are much more powerful bass, which I assume comes from the current capability of the F4, and a delightful clarity in the top end...Best of all, superb dynamics."
Alexis made an interesting comment in the diystore under F-4:"I first bought an F5 kit from DIY audio store. It was an awesome sounding amplifier but I felt it had too much gain for my system (I have very sensitive speakers). I then got the F4 amplifier PCBs, that I could use in the same chassis I used for the F5 (I had to augment the PSU with another board for more capacitance). The F4 is perfect for my system, I don't have to listen at very low volume setting anymore butt I still do have plenty of room to increase volume if needed. The sound is great. The F5 has exceptionally fast transients and a somewhat lean sound with tons of details. The F4 has a more relaxed presentation, not as fast as the F5, but I felt the sound has very wide soundstage, and the details are still there. Very enjoyable to listen to. Overall I am very happy with this amp, that I know will remain in my system for a long time. I am very pleased with the service from DIY Audio Store, and the quality of the PCBs and parts they provide. Thank you!"
So perhaps the F-4 is a sweeter F-5, lots of detail but dialed back to sound less "harsh"... a nice keyword here is "very wide soundstage".. big and wide soundstage is ofc welcome.
From Pass himself: "The combination of a simple Class A circuit operated without feedback and the good objective performance gives us a superb sounding amplifier. The low distortion, bandwidth extension, and high damping results in midrange clarity, treble detail, and control on the bottom end. While these are available from most good solid state amplifiers, the F4 also brings depth, imaging, midrange warmth and top-end sweetness."
😀
***
And what does 6moons have to say about the F-4 and F-5:
F-4: with your preamp. A standard active preamp should be perfectly sufficient to fill the usual digs with high sound pressures over standard 90dB speakers. Alas, your preamp still couldn't strap to your speakers directly even with a custom cable. Despite being equipped with perfectly adequate X factor to generate all the desired loudness, high output impedance and insufficient current delivery conspire against actually driving the speakers with a preamp. Enter the F4 follower amp with current -- not voltage -- gain.
- This amp delivers +/- 20 volts in single-ended mode, double that in mono. Frequency response is 0.1Hz to 200kHz -0.5dB and power consumption is 160 watts. "As you drop below 87dB speaker sensitivity, you will want to consider 100-watt balanced monoblock operation, with a preamp capable of swinging 14 volts per balanced output and having a gain of 20dB+. As your loudspeaker increases in sensitivity, you need less gain and less voltage swing."
- This means that your top-class preamp finally gets to stretch its legs. It is allowed to enter a more optimized RPM and torque zone. No longer does it barely get out of first gear. Previously, preamp and amp gain added up to so much loudness that your listening took place well below full source output voltage. With the F4, one X factor is eliminated. With it, all chances to amplify preamp noise or running your preamp below 9:00 on the dial are eliminated as well. It's an elegantly simple though unconventional antidote for 'gain poisoning'.
- Before we consider sonics, a reminder. The F4 soars or sinks on the strength of your preamp ... Glad I have secured the UGS Muses preamp.
- Already into early listening sessions, the F4 had me work my phrase maker to clearly define its most obvious flavor: relaxed ultra resolution. Like a seed mantra, those three words are potent. There's the inherent polarity of what's often mutually exclusive. 'Relaxed' is a state of being. In the context of fine audio, 'resolution' as such is recognized by mental faculties. It involves a kind of activity, an alertness to stay put or else the notion of resolution evaporates. 'Hyper resolution' is its extreme expression. The act of listening has become tense, unnatural and exhausting. 'Ultra' is similarly heightened but lacks the negative spin. Now make the two polarities meet in the middle: a relaxed open state of non-mental being that's free of concerns. It's thus free also to effortlessly perceive a tremendous amount of very fine aural detail if that's what happens to present itself. But this doesn't trigger any active collection from us. It simply is.
F-5: The latest in the F series (which might stand for fun or fabulous or far out) is the F5 which follows numerically on the heels of the F4 buffer/follower amp.
- Taking pity on prospective and already committed F5 rollers for lacking any type of audition feedback when none had finalized their own DIY variants yet to post sonic impressions for the fence sitters, Nelson Pass then did something quite out of character. He commented on the sound of his own amplifier, something he usually leaves to others: "The F4 is the closest relative. They both have a clean extended bottom and I consider them almost equivalent, with neither having a distinct advantage. The F4 is a little bit warmer in the mid and might be preferred on simple material at modest volume levels, that is to say a solo vocal or instrument or maybe a string quartet. You could say it's a little more tubey.
- by retaining more clarity - specifically less IM type distortion. As a result it does a better job with articulation of instruments. There is a little less smearing. If you have a pair of full range drivers, Lowther PM6A or Feastrex D9nf, the F5 brightens the top end up just a bit, adding a touch of tintinabulation that we all like, although it also heightens the perception of response peaks a little more. In this category, if you find the high efficiency full rangers too bright with the F4 or F5, the F3 is perhaps the more appropriate amp. The imaging is very good with both of these amps in my system, and I haven't heard enough difference to make a decision on that, but the localization is pleasing. The open baffle speakers I'm using already have a big ambient soundstage and would probably do that with any decent amplifier. The F4 is a little more relaxed all around, the F5 carries a little more detail."
- "As the volume rises and the complexity of the material increases, the F5 pulls ahead.
- Fade to second act. What's it sound like?
- Like a true FirstWatt amp, meaning it comes alive at whisper levels - to a clearly superior extent than my treasured Yamamoto A-09S 300B zero feedback SET. This made me suspect that in admiral Nelson's universe, this was more of what he refers to as a 3rd-order than 2nd-order amp. I was sure I'd find out more soon enough.
- So the F3 is sweeter. A mini triode dose. As exceptionally transparent as it is to the preceding preamp literally doing the driving, the F4 is more limpid. It doesn't 'grip' but floats and flows. The F5 articulates. That very first impression held.
- Allow me a brief detour to stress the point. Certain erotic movies celebrate their protagonists as pursuing ever more outlandish means to sexual gratification. It's as though their continued use of toys, fetishes, strangulation and pain severely desensitized them to require ever more bizarre measures of stimulation. The less one feels, the more effort must be made to elicit the desired response. The same occurs with junk foods' high saturation of salt, sugar and fats. Once a palate has been dulled by such assaults, eggs or veggies not tarted up with salt and sauces become tasteless and boring - for simply tasting like themselves. The F5 invites such ruminations and applies them to the habits of us valve addicts. Compared to a Halcro's nonexistent distortion, tube THD seems completely justified to our kind; in fact, outright necessary. Why then is it that faced with the F5's impossibly low distortion (impossible certainly for any tube amp), thermionic liberties suddenly seem far less justified or necessary? Are valvers addicted to unnatural stimulation?
- I don't have the answer. It's an open question to point at something real but elusive. The technical purity of the F5 isn't flat. Its feedback causes no dryness; its proud specmanship has real relevance to the experience. But it certainly doesn't sound like my glowing amps. As you prime their pump, they come into their own with great tone density. Viewed from the F5's seat, there's less resolution within that density. There's less separation; less residual grunge around a faint muted trumpet, less swishiness on swirling cymbal brushes, less ephemeral glitter on bell trees. Something congeals. Greater loudness distracts from it but truly subdued midnight levels with the SETs obscure. One can no longer enter into the music. A door closes. One stands outside and removed. The glowing bottles clearly suffer when my wife is already dreaming and I'm still chasing the tunes and the most immaterial of fades.
- Viewing things from the strengths of the glowing bottles when their amplitude is sufficient to skip over that get-real hurdle, the F5 is leaner. Less padding of tonal girth. But it doesn't sound lean per se. It's completely beyond threadbare (and granted, I ran the 12dB-gain tubed ModWright LS/PS 36.preamp at 3:00 o'clock + on the above Zu Presence). There's more treble tintinabulation to re-use Nelson's crafty term. That action doesn't saturate timbres like 2nd-order octave doubling does with tubes. It instead increases finesse of insight and subtle energy. After all, upper harmonics are high in frequency and subdued in output. To track them requires extension and ultra-low noise floor. Then the live factor survives when you dim the volume lights. Loudness is often a substitute to create the illusion of seeing more. Then we forget what we really don't see. It's compensation. It proves out insufficient illumination at quieter levels. In plain speak, that's inferior and ultimately insufficient resolution. The need for SPLs nearly always signifies it.
- In the world of FirstWatt, the F1 had the strongest 3rd-order flavor. Super articulation. Separation. Crispness. And drive. The F1 sounded driven. Propulsive, a clear personality. The F4 and F5 are rather more relaxed entries in that domain, with the F5 slightly more gathered up and sorted than the F4. The buffer/follower amp is the most kif of the bunch as the stamboulis would look for in an opium den - supremely relaxed, in a go-with-the-flow state. The F2 and F3 are sweeter and 'rounder', with the F3 deepest into that particular terrain, the F2 just slightly. In general, numbers 3 to 5 strike me as closer to the center than the first two.
- Take anything massed -- a chorus, symphonic strings à la Samuel Barber -- and as predicted by Mr. Pass, the degree of sight the listener enjoys into that layered action from the 5 is brilliant. Take anything speedy and sharp -- rapidly plucked strings, blatty brass, drum kit workouts -- and the F5 is clear and incisive but never brutal and hard. Except for the F1, none of the FirstWatt amps struck me as bass monsters. As a transconductance amp, the F1 could only be properly used on crossoverless widebander speakers. Those are never really endowed in that sense, making what the F1 got from them just shy of freakish but still quite relative in the bigger scheme of what's ultimately possible from 15" woofers.
- Take soundstaging -- depth, width, localization, stability -- and the F5 is a champ. No drift, no wander, no blur. No etch or grippiness neither. The F4 appears even 'floatier' but those are very subtle matters appreciable only in a direct comparison. Which of course is what the man already said in his own words. Nelson is definitely equipped to not just design amplifiers but review them objectively. Take microdynamics -- those heart palpitations caused by a singer's or instrumentalist's unexpectedly emphatic inflections -- and I'd have to call the F5 superior to my most cherished valve amps. If that's directly related to circuit speed, the F5 certainly lives up to that obnoxiously ideal square wave graph we admired earlier. This returns us, again, to that ability for remaining involving at very subdued levels. There's enough wiggly, jumpy, kicking live factor left to be interesting and gratifying. It's all there, not lost in any THD fog.
- Curtain time. The F5 brings the Nelson Pass sonics explored in the present FirstWatt range to 25wpc needers with enough gumption for 2 ohms. Be aware though that 15dB of amplifier gain isn't very much. To serve up 90dB speakers in style, you'll want 20 - 25dB in your preamp . Not that those are FirstWatt's focus. But the F5 could be a back-door opportunity for those not subscribed to the hi-eff religion. You'll simply no longer be running the amp inside that first watt where its distortion drops off the map. Nelson predicted that some listeners would like the F5 best of the bunch. I certainly see why. As much as an audiophile floozie can at any given day, I might just share that opinion in fact. It's unmistakably the most universal FirstWatt yet, with the high-power 'muscle' versions of F3 thru F5 already announced to welcome those with even harder-of-hearing speakers into the fold
-----
Relaxed is a "dangerous" word in my book because it often mean boring. But crisp and detailed is for others equally dangerous since they read that is sounding harsh and sibilant. But fear not since sibilance comes from the tweeter, so as long as the tweeter does not compromise the loudspeaker, we should be fine.
So... is the F-5 platform my choice ????
Other comments:
"F5 very fast and detailed, bit dry. F4 more ''Musical'' can sound great with tube preamp." and "My mate built the F5, I've borrowed it a few times, but for me F4 & pumpkin is very hard to beat very musical."
"The F4 is, in a word, better. The main differences I'm hearing are much more powerful bass, which I assume comes from the current capability of the F4, and a delightful clarity in the top end...Best of all, superb dynamics."
Alexis made an interesting comment in the diystore under F-4:"I first bought an F5 kit from DIY audio store. It was an awesome sounding amplifier but I felt it had too much gain for my system (I have very sensitive speakers). I then got the F4 amplifier PCBs, that I could use in the same chassis I used for the F5 (I had to augment the PSU with another board for more capacitance). The F4 is perfect for my system, I don't have to listen at very low volume setting anymore butt I still do have plenty of room to increase volume if needed. The sound is great. The F5 has exceptionally fast transients and a somewhat lean sound with tons of details. The F4 has a more relaxed presentation, not as fast as the F5, but I felt the sound has very wide soundstage, and the details are still there. Very enjoyable to listen to. Overall I am very happy with this amp, that I know will remain in my system for a long time. I am very pleased with the service from DIY Audio Store, and the quality of the PCBs and parts they provide. Thank you!"
So perhaps the F-4 is a sweeter F-5, lots of detail but dialed back to sound less "harsh"... a nice keyword here is "very wide soundstage".. big and wide soundstage is ofc welcome.
From Pass himself: "The combination of a simple Class A circuit operated without feedback and the good objective performance gives us a superb sounding amplifier. The low distortion, bandwidth extension, and high damping results in midrange clarity, treble detail, and control on the bottom end. While these are available from most good solid state amplifiers, the F4 also brings depth, imaging, midrange warmth and top-end sweetness."
😀
***
And what does 6moons have to say about the F-4 and F-5:
F-4: with your preamp. A standard active preamp should be perfectly sufficient to fill the usual digs with high sound pressures over standard 90dB speakers. Alas, your preamp still couldn't strap to your speakers directly even with a custom cable. Despite being equipped with perfectly adequate X factor to generate all the desired loudness, high output impedance and insufficient current delivery conspire against actually driving the speakers with a preamp. Enter the F4 follower amp with current -- not voltage -- gain.
- This amp delivers +/- 20 volts in single-ended mode, double that in mono. Frequency response is 0.1Hz to 200kHz -0.5dB and power consumption is 160 watts. "As you drop below 87dB speaker sensitivity, you will want to consider 100-watt balanced monoblock operation, with a preamp capable of swinging 14 volts per balanced output and having a gain of 20dB+. As your loudspeaker increases in sensitivity, you need less gain and less voltage swing."
- This means that your top-class preamp finally gets to stretch its legs. It is allowed to enter a more optimized RPM and torque zone. No longer does it barely get out of first gear. Previously, preamp and amp gain added up to so much loudness that your listening took place well below full source output voltage. With the F4, one X factor is eliminated. With it, all chances to amplify preamp noise or running your preamp below 9:00 on the dial are eliminated as well. It's an elegantly simple though unconventional antidote for 'gain poisoning'.
- Before we consider sonics, a reminder. The F4 soars or sinks on the strength of your preamp ... Glad I have secured the UGS Muses preamp.
- Already into early listening sessions, the F4 had me work my phrase maker to clearly define its most obvious flavor: relaxed ultra resolution. Like a seed mantra, those three words are potent. There's the inherent polarity of what's often mutually exclusive. 'Relaxed' is a state of being. In the context of fine audio, 'resolution' as such is recognized by mental faculties. It involves a kind of activity, an alertness to stay put or else the notion of resolution evaporates. 'Hyper resolution' is its extreme expression. The act of listening has become tense, unnatural and exhausting. 'Ultra' is similarly heightened but lacks the negative spin. Now make the two polarities meet in the middle: a relaxed open state of non-mental being that's free of concerns. It's thus free also to effortlessly perceive a tremendous amount of very fine aural detail if that's what happens to present itself. But this doesn't trigger any active collection from us. It simply is.
F-5: The latest in the F series (which might stand for fun or fabulous or far out) is the F5 which follows numerically on the heels of the F4 buffer/follower amp.
- Taking pity on prospective and already committed F5 rollers for lacking any type of audition feedback when none had finalized their own DIY variants yet to post sonic impressions for the fence sitters, Nelson Pass then did something quite out of character. He commented on the sound of his own amplifier, something he usually leaves to others: "The F4 is the closest relative. They both have a clean extended bottom and I consider them almost equivalent, with neither having a distinct advantage. The F4 is a little bit warmer in the mid and might be preferred on simple material at modest volume levels, that is to say a solo vocal or instrument or maybe a string quartet. You could say it's a little more tubey.
- by retaining more clarity - specifically less IM type distortion. As a result it does a better job with articulation of instruments. There is a little less smearing. If you have a pair of full range drivers, Lowther PM6A or Feastrex D9nf, the F5 brightens the top end up just a bit, adding a touch of tintinabulation that we all like, although it also heightens the perception of response peaks a little more. In this category, if you find the high efficiency full rangers too bright with the F4 or F5, the F3 is perhaps the more appropriate amp. The imaging is very good with both of these amps in my system, and I haven't heard enough difference to make a decision on that, but the localization is pleasing. The open baffle speakers I'm using already have a big ambient soundstage and would probably do that with any decent amplifier. The F4 is a little more relaxed all around, the F5 carries a little more detail."
- "As the volume rises and the complexity of the material increases, the F5 pulls ahead.
- Fade to second act. What's it sound like?
- Like a true FirstWatt amp, meaning it comes alive at whisper levels - to a clearly superior extent than my treasured Yamamoto A-09S 300B zero feedback SET. This made me suspect that in admiral Nelson's universe, this was more of what he refers to as a 3rd-order than 2nd-order amp. I was sure I'd find out more soon enough.
- So the F3 is sweeter. A mini triode dose. As exceptionally transparent as it is to the preceding preamp literally doing the driving, the F4 is more limpid. It doesn't 'grip' but floats and flows. The F5 articulates. That very first impression held.
- Allow me a brief detour to stress the point. Certain erotic movies celebrate their protagonists as pursuing ever more outlandish means to sexual gratification. It's as though their continued use of toys, fetishes, strangulation and pain severely desensitized them to require ever more bizarre measures of stimulation. The less one feels, the more effort must be made to elicit the desired response. The same occurs with junk foods' high saturation of salt, sugar and fats. Once a palate has been dulled by such assaults, eggs or veggies not tarted up with salt and sauces become tasteless and boring - for simply tasting like themselves. The F5 invites such ruminations and applies them to the habits of us valve addicts. Compared to a Halcro's nonexistent distortion, tube THD seems completely justified to our kind; in fact, outright necessary. Why then is it that faced with the F5's impossibly low distortion (impossible certainly for any tube amp), thermionic liberties suddenly seem far less justified or necessary? Are valvers addicted to unnatural stimulation?
- I don't have the answer. It's an open question to point at something real but elusive. The technical purity of the F5 isn't flat. Its feedback causes no dryness; its proud specmanship has real relevance to the experience. But it certainly doesn't sound like my glowing amps. As you prime their pump, they come into their own with great tone density. Viewed from the F5's seat, there's less resolution within that density. There's less separation; less residual grunge around a faint muted trumpet, less swishiness on swirling cymbal brushes, less ephemeral glitter on bell trees. Something congeals. Greater loudness distracts from it but truly subdued midnight levels with the SETs obscure. One can no longer enter into the music. A door closes. One stands outside and removed. The glowing bottles clearly suffer when my wife is already dreaming and I'm still chasing the tunes and the most immaterial of fades.
- Viewing things from the strengths of the glowing bottles when their amplitude is sufficient to skip over that get-real hurdle, the F5 is leaner. Less padding of tonal girth. But it doesn't sound lean per se. It's completely beyond threadbare (and granted, I ran the 12dB-gain tubed ModWright LS/PS 36.preamp at 3:00 o'clock + on the above Zu Presence). There's more treble tintinabulation to re-use Nelson's crafty term. That action doesn't saturate timbres like 2nd-order octave doubling does with tubes. It instead increases finesse of insight and subtle energy. After all, upper harmonics are high in frequency and subdued in output. To track them requires extension and ultra-low noise floor. Then the live factor survives when you dim the volume lights. Loudness is often a substitute to create the illusion of seeing more. Then we forget what we really don't see. It's compensation. It proves out insufficient illumination at quieter levels. In plain speak, that's inferior and ultimately insufficient resolution. The need for SPLs nearly always signifies it.
- In the world of FirstWatt, the F1 had the strongest 3rd-order flavor. Super articulation. Separation. Crispness. And drive. The F1 sounded driven. Propulsive, a clear personality. The F4 and F5 are rather more relaxed entries in that domain, with the F5 slightly more gathered up and sorted than the F4. The buffer/follower amp is the most kif of the bunch as the stamboulis would look for in an opium den - supremely relaxed, in a go-with-the-flow state. The F2 and F3 are sweeter and 'rounder', with the F3 deepest into that particular terrain, the F2 just slightly. In general, numbers 3 to 5 strike me as closer to the center than the first two.
- Take anything massed -- a chorus, symphonic strings à la Samuel Barber -- and as predicted by Mr. Pass, the degree of sight the listener enjoys into that layered action from the 5 is brilliant. Take anything speedy and sharp -- rapidly plucked strings, blatty brass, drum kit workouts -- and the F5 is clear and incisive but never brutal and hard. Except for the F1, none of the FirstWatt amps struck me as bass monsters. As a transconductance amp, the F1 could only be properly used on crossoverless widebander speakers. Those are never really endowed in that sense, making what the F1 got from them just shy of freakish but still quite relative in the bigger scheme of what's ultimately possible from 15" woofers.
- Take soundstaging -- depth, width, localization, stability -- and the F5 is a champ. No drift, no wander, no blur. No etch or grippiness neither. The F4 appears even 'floatier' but those are very subtle matters appreciable only in a direct comparison. Which of course is what the man already said in his own words. Nelson is definitely equipped to not just design amplifiers but review them objectively. Take microdynamics -- those heart palpitations caused by a singer's or instrumentalist's unexpectedly emphatic inflections -- and I'd have to call the F5 superior to my most cherished valve amps. If that's directly related to circuit speed, the F5 certainly lives up to that obnoxiously ideal square wave graph we admired earlier. This returns us, again, to that ability for remaining involving at very subdued levels. There's enough wiggly, jumpy, kicking live factor left to be interesting and gratifying. It's all there, not lost in any THD fog.
- Curtain time. The F5 brings the Nelson Pass sonics explored in the present FirstWatt range to 25wpc needers with enough gumption for 2 ohms. Be aware though that 15dB of amplifier gain isn't very much. To serve up 90dB speakers in style, you'll want 20 - 25dB in your preamp . Not that those are FirstWatt's focus. But the F5 could be a back-door opportunity for those not subscribed to the hi-eff religion. You'll simply no longer be running the amp inside that first watt where its distortion drops off the map. Nelson predicted that some listeners would like the F5 best of the bunch. I certainly see why. As much as an audiophile floozie can at any given day, I might just share that opinion in fact. It's unmistakably the most universal FirstWatt yet, with the high-power 'muscle' versions of F3 thru F5 already announced to welcome those with even harder-of-hearing speakers into the fold
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Relaxed is a "dangerous" word in my book because it often mean boring. But crisp and detailed is for others equally dangerous since they read that is sounding harsh and sibilant. But fear not since sibilance comes from the tweeter, so as long as the tweeter does not compromise the loudspeaker, we should be fine.
So... is the F-5 platform my choice ????
I am listening to UGS with balanced F4s right now. Although UGS has gain, mine does not quite produce the full desired voltage swing. So the preamp clips before the power amps. My speakers are efficient so this does not bother me too much. The system has good synergy overall.
Some ideas:
- tube preamp are king of voltage swing (Aikido is an explosive blast)
- SIT preamp like the Luminaria (on my build list when I retire)
- adding an input transformer to double voltage in F4 (I remember seeing a thread on this somewhere)
The F4 is worth the effort IMO. Just my two cents...
Some ideas:
- tube preamp are king of voltage swing (Aikido is an explosive blast)
- SIT preamp like the Luminaria (on my build list when I retire)
- adding an input transformer to double voltage in F4 (I remember seeing a thread on this somewhere)
The F4 is worth the effort IMO. Just my two cents...