[BrandonB]

Brandon, I ended up getting a QX-5 Twenty recently.  I had an Ayre QB-9 Twenty as well, and wondered how it would compare SQ wise (the QX-5 is much more flexible).  I've spoken to Jake at Ayre quite a bit and trusted his advice to get it, based on other stuff I have.  Anyway, it's friggin' awesome.  Incredible clarity.  I mean - Incredible.  I wanted to "hear" the QX-5, so I pulled the KX-R Twenty and using the QX-5 Twenty as Preamp / DAC into Ayre MX-R monos, or Ayre VX-5 Twenty.  I'll probably put the KX-R Twenty back in over the weekend.  Really curious to hear what happens... I've tried "going direct" before with not preamp with RME ADI-2/4 Pro.  It was REALLY good, but not as good as having my KX-5 Preamp or KX-R preamp in. 

A great preamp is additive, in my experience, for overall presence and dynamics.  Good conversation here and different ways of getting to great sound.  I think this stuff has something important in common though... it's DIFFERENT than the stuff designed to be flashy and talk very little about what's inside.  I sometimes wonder how many bother to look into what's INSIDE the equipment, how is it designed, what's the philosophy (do they even have a philosophy other thank flashy casework?),

"How is this amp different than some other solid state amp, besides the marketing materials?"

Notwithstanding any of that, if you want something turn key, that will sound incredible... pickup a QX-5 Twenty and VX-5 Twenty.  I think both can be had for ~$10k (used / finding deals) and it can be end game stuff - I think the VX-5 Twenty is that good.  The VX-8 may also be a great fit, but if you have interest in QX-5 Twenty, I'd get it.  Also, and mentioned before, the VX-5 Twenty (and VX-8) has modules available you can insert for High Pass.  It's a very small cap value.  Vandersteen does this with their speakers and likes Ayre equipment.  They use 100Hz, but I'm sure Ayre will put whatever you want on there. In fact, might not be a bad idea to contact Danny about those small Sonicaps he has.  I have 2 different pairs of them from Danny to target 100Hz and 160Hz - in case I wanted to use an outboard box.  I think Danny likes the high pass under 100Hz, so I'll probably pick up a batch to try that as well.

This is the high pass module. You'll see the value is .0015uF, which yields 100Hz. That's because the input impedance of several Ayre amps is 2Mohm (balanced) - 1Mohm per leg.  So, the cap can be very small and a high quality cap is very affordable.

Anyway, I keep spending money on this gear and speaker stuff from Texas and it keeps getting better - why change?  Now I need to hear a ribbon tweeter cross at 1Khz.  

Dude you have gone all out on the Ayre side.  How does the QX-5 twenty sound without a preamp?  Are you also using it to stream?  Have you gotten your Mono's back from Ayre?  That's going to be a kiler system. 

[jmimac351]

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[mkrawcz]

So that F5M can be built, properly, with all the right stuff - for <$500?

Pretty much. It all depends on how much the chassis costs. The rest of the amp has so few parts that they simply do not add up to much money. Diyaudiostore told me the other day they will have a whole new line of Deluxe chassis available "in a few months if all goes well". Those chassis will likely have all the predrilled/tapped holes for the Firstwatt DIY amps.

[jmimac351]

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[jmimac351]

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[KTS]

This is very compelling.  My Ayre stuff has no coupling caps either, runs from DC.  That is the one thing that has bugged me about doing any high-pass... I'll be putting a capacitor where none exist, and "messing with that detail".  Or, is it more detail in the end because of rolling off those frequencies...better midrange, but what happens to air. I have wanted to try the First Watt stuff, to know what it is / experience it.  That has always been a "not in stock / buy used for $4k" thing.  If Nelson really is sharing "the good stuff, if you're willing to build it" in this F5M, that really is quite a gift to the DIY community.  Sounds like he is as I see the excitement in conversations over there.

Have you guys figured out which one of you is going to let me send you a UPS label for your extra F5M? 

If you want to try the Aleph J, I have a set of built Aleph J boards I pulled out to build the Aleph Jzm, you will need everything else. There is an excellent build guide on DIY Audio. The components are all from the DIY Audio Store, everyone need an Aleph!

[jmimac351]

If you want to try the Aleph J, I have a set of built Aleph J boards I pulled out to build the Aleph Jzm, you will need everything else. There is an excellent build guide on DIY Audio. The components are all from the DIY Audio Store, everyone need an Aleph!

Very, very kind.  I got your message and responded. Thank you.

[jmimac351]

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[mkrawcz]

The Amp Camp Amps have been interesting, but I'm glad it's over.  15 watts isn't enough for me, but probably would be for some.  There is a very large gap in sound quality from what I've grown accustomed to, which is curious to me as I think about the reviews of the amps.  "For the money" applies.  Reading thru the First Watt site, the amp descriptions are great.  I think there are 17 in total?  These are the ones I'd have interest in hearing, and they all happen to be buildable. 

@jaytor, I think I know why you are building the F5... huge bandwidth from DC, no caps anywhere, etc.  Very nice!

Everyone of those amps is outstanding. They each have a unique character. Personally, of all those listed, the M2 is my favorite. Particularly the M2X version on the Diyaudiostore with the Milpitas input board. It’s the amp that stays in more than any other amp I own. But the M2X is a bit of a project. There are no kits, you get the amp PCBs and everything else you source.

[Jaytor]

As I mentioned previously, I prefer the sound of the F5M to the F5. While it uses the same basic topology, there are enough differences in the circuit to change the way it sounds.

The current-limiting and temperature compensation circuits are eliminated. This current limiting circuit protects the amp if the outputs are shorted, but I think it has some minor adverse sonic effects by causing some dynamic compression. The temperature compensation circuit adds thermistors in the bias circuit which I am sure are not as clean sounding as high quality resistors. Removing them increases the time to fully warm up (and increases the amount of time it takes to set the bias when you are powering up for the first time), but I'm willing to accept this to get the best SQ. The F5M also uses different output devices which shift the distortion profile to be 2nd order dominant. And finally, the F5M has a bit less overall negative feedback.

The result of all these changes is an amp that sounds cleaner and more dynamic, with an improved soundstage width and depth.

I'd like to build an M2X at some point. That looks like an interesting amp.

[mkrawcz]

As I mentioned previously, I prefer the sound of the F5M to the F5. While it uses the same basic topology, there are enough differences in the circuit to change the way it sounds.

The current-limiting and temperature compensation circuits are eliminated. This current limiting circuit protects the amp if the outputs are shorted, but I think it has some minor adverse sonic effects by causing some dynamic compression. The temperature compensation circuit adds thermistors in the bias circuit which I am sure are not as clean sounding as high quality resistors. Removing them increases the time to fully warm up (and increases the amount of time it takes to set the bias when you are powering up for the first time), but I'm willing to accept this to get the best SQ. The F5M also uses different output devices which shift the distortion profile to be 2nd order dominant. And finally, the F5M has a bit less overall negative feedback.

The result of all these changes is an amp that sounds cleaner and more dynamic, with an improved soundstage width and depth.

I'd like to build an M2X at some point. That looks like an interesting amp.

I totally agree on the F5M. I don’t think anyone can go wrong with either one. The lower mid and upper bass “resolution” of the F5M is without a doubt the best I’ve heard from any other amp I’ve experienced. I am actually excited to get my hands on those F5M monoblocks from Reduxkits.

[jmimac351]

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[mkrawcz]

I have not been able to compare the Pass Labs to the First Watts directly, but Nelson Pass himself said the Pass Labs amps are not an improvement over the First Watt amps. On the M2X, the Austin as well as the different boards are an input buffer. The Austin a tricky one to soldier up because there are are a lot of parts really close together. I haven’t tried that one yet, but I’m sure it’s quite good. I guess I will have to put in a Mouser parts order.  The nice thing is the input boards are quick and easy to change out.

[jmimac351]

Cool!  That's a thing about this hobby... it's too bad people don't live closer together to trade / test drive gear, etc.  That would be fun.  That would save a lot of wondering and expense.

[KTS]

I have not been able to compare the Pass Labs to the First Watts directly, but Nelson Pass himself said the Pass Labs amps are not an improvement over the First Watt amps. On the M2X, the Austin as well as the different boards are an input buffer. The Austin a tricky one to soldier up because there are are a lot of parts really close together. I haven’t tried that one yet, but I’m sure it’s quite good. I guess I will have to put in a Mouser parts order.  The nice thing is the input boards are quick and easy to change out.

I have built it, but I need to test before I slap it in the Amp. It is a tight layout that needs testing when a noob like me builds it.

[Jaytor]

The F5M and the M2X are probably the ones I'd pick to hear.  Is there any consensus about these amps in terms of sound quality compared to the retail Pass Labs designs, e.g., Pass Labs XA-30 (Class A 30 watt).  These amps are right there in power compared to the XA-30, and I'm sure there are differences in presentation between them. 

Bottom line, can a $500 DIY F5M / M2X First Watt amp run with, or even better, the Pass Labs XA-30?

I had a pair of XA-60.8 monoblocks for a while, but I sold them early last year so I haven't done a direct comparison. The commercial Pass amps are very well built with a fair amount of the cost in the casework, connectors, meter, etc. I would say that they are more robust with a larger power supply and more output transistors in parallel, so they can probably handle very low impedance loads a bit better. If you build one of the First Watt clones with a good power supply, it should hold its own very well against the commercial Pass amps, at least for a reasonably sensitive speaker without excessively low impedance dips. I don't think the First Watt amps will do as well with low sensitivity speakers with impedance dips below 2 ohms.

[jmimac351]

Jay, could you have built your amps, with your mods, as mono blocks for higher output?  I think you have them as stereo for bi-amping.  I'm listening to an amp on the Duette that is 60w 8ohm / 120w 4ohm - and that's probably my number.

[Jaytor]

The easiest way to do this with the F5M circuit would be to bridge the two channels. I’d probably still use an input transformer to make sure the two phases are well balanced. This would probably limit how low an impedance you can drive effectively though, and they would switch to class A/B operation at a lower power level.

[jmimac351]

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[mkrawcz]

Just got my Iron Pre balanced up and running. This thing is Mighty! The problem now is I have to finish wiring up all the inputs and that involves turning it off.