[Jaytor]

That is very cool indeed.  I thought it was a "boutique product from an OEM I don't know much about".   Really, really nicely done.

So... and asking for a friend (or two), you can take a drawing and put it into "CAD Language to take to a place with CNC machine and cut wood" kind of CAD skills?

How much free pizza and beer can you consume in one sitting?  Maybe you can point me in the direction for the best way to figure out how to do that (if that's not laughable for not understanding how hard it is to do).

Thank you.

I've never tried to do wood CNC. For the electronic enclosures, I am using the free software that Front Panel Express (FPE) provides. This allows fairly simple machining of aluminum panels. You can specify cutouts, partial depth machining, threaded and non-threaded holes and blind holes, edge finish, engraving, etc., as well as finish type (anodized, powder-coated, etc.). FPE is not inexpensive though. This enclosure cost me several thousand dollars for all the panels.

If you used a program such as Fusion360 or OnShape, there are online machine shops that are a bit cheaper, but I haven't spent the time to learn these packages yet. Also, I like having a somewhat consistent look with the projects I am building, and getting matching powder coating from other vendors is a bit more challenging (although if I'm willing to wait a few weeks, I can have stuff powder coated locally like I did for the knobs I am used for this project).

[Jaytor]

Jay, out of curiosity, what wire did you use going to the XLRs? Looking for some good wire for my Iron pre.

I used DH Labs AG-23 hookup wire. This is 23ga solid silver wire with PTFE insulation. 

[Jaytor]

I am sending my Ayre MX-R monos to be upgraded to the "Twenty" series.  It essentially means they will return as a new (internally), different amps.  The circuit is completely different and uses their latest design language (Diamond Circuit).  The boards / caps are swapped - I think only the transformers remain.

While those are gone, tomorrow morning, I'm picking up a pair of Nelson Pass Amp Camp amps for $350, for the pair (FakeBook Marketplace).  They have very low damping factor and I think it will be interesting to play with them.

I have a "spare" RME ADI-2 DAC FS unit for source that will make dinner and PBJ sammiches, if you want it to.  It does everything, and it sounds really good.  With those 3 things, RME / Pass Monos, I think I will have an entire system setup for $1267 (bought used).  Perhaps it will be of interest to others... you don't "have to spend a lot of money".

I know some of you have played with the Amp Camp amps.  I have heard Danny's "chip amps" and noted one thing in particular about the presentation, and I don't know if it was "amps / front end" or "tweeter" or "new system to me"... all of the above probably. 

Buy Used / Learn / Sell and not get hurt $$$ / Repeat.

Having fun.

Good luck with your Ayre upgrade. They have a good reputation, so I expect you will be pleased.

I recently completed a couple of stereo amps that utilize the First Watt F5M circuit that Nelson presented at Burning Amp last year. The DIYAudioStore has kits available for PCB boards and components for a fairly simple build (not much more complicated than the Amp Camp Amp).

I did my own PCBs since I wanted to use a more sophisticated power supply and add some additional features (balanced input, speaker protection circuit, and DC servo). This is a very nice sounding amp with modest feedback and a nice second harmonic dominant distortion profile. It produces ~25w/channel into 8 ohms (50w into 4).

I built two amps so I could try bi-amping my Line Forces (haven't had a chance to try yet). Here's some photos.







I repurposed some enclosures I bought on ebay that I had used for a previous build.

[mkrawcz]

There is a “Redux” monoblock F5M kit in the works by Nelson Brock on diyaudio. The kits are just like his version of the Amp camp amp that is all PCB attached to a fan cooled heatsink using an external switched mode power supply. These will be a really nice sounding class A amp and anyone interested in what might be the easiest way to have a world class DIY Nelson Pass amp should check it out.

[jmimac351]

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[jmimac351]

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[mkrawcz]

This is how rashes and nervous ticks spread from person to person...    The other thing I was thinking was I could repurpose the ACA to my office.  For the little time I spend in there, the other day I wanted something I could flip on and play, and sound good.

For those wondering how to try gear... buy at <65% of retail, preferably closer to 50% (if you can).  You have to take time to learn the market for a piece.  Should be able to get out of it without getting hurt.  For used $350 DIY amps, am I going to fool with selling them when they are probably cool little units that I will like?  Probably not, but I have a spot for them other than collecting dust.

Have a plan for how you're going to get out of it, or a spot for it - or you do not buy.  If you do, you may lose money and that may be OK for what you will experience / learn, or end up with a pile of stuff you don't want anymore and it's standing in the way of what you realize you want / need.

That's what I'm doing and it is working very well.

To put into perspective the money one can save on DIY. The original production Firstwatt F5 was $4,000. These new F5M Monoblock kits are estimated to be around $480 for a pair. Thats a pretty good deal for one of the best amps Nelson Pass ever designed. Not all DIY projects yield great results, but this amp is the best price vs performance amp I've come across. And because it's probably the simplest class A circuit possible while remaining stable, it's really easy to build.

[Jaytor]

To put into perspective the money one can save on DIY. The original production Firstwatt F5 was $4,000. These new F5M Monoblock kits are estimated to be around $480 for a pair. Thats a pretty good deal for one of the best amps Nelson Pass ever designed. Not all DIY projects yield great results, but this amp is the best price vs performance amp I've come across. And because it's probably the simplest class A circuit possible while remaining stable, it's really easy to build.

In my opinion, the F5M sounds better than the F5 (at least the F5 I built). Both the F5 and F5M have nice distortion profiles with steadily decreasing higher order peaks, but the F5M has a dominant 2nd order peak while the F5 has a dominant 3rd order peak, which might explain the difference. I found the F5M to have a smoother response and great bass performance.

[jmimac351]

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[Jaytor]

I’ve been using one of my F5M amps in my workshop system using Totem Mani-2 speakers (85db sensitivity) and even with these speakers which are much harder to drive than the NX-Oticas, the F5M does a pretty good job. The room isn’t huge (maybe 13’ x 15’), and you can hear them start to strain a bit if you crank them up too loud, but I think they’d doing pretty well driving the NX-Oticas at reasonable volume levels.

Before I built my Line Forces, I was using my 300B PSET amps with my NX-Oticas and had no problem driving them louder than I’d ever listen to them at. So I don’t think you need a ton of power with these speakers.

[mkrawcz]

Thanks for sharing that, fellas. I wasn't aware of the F5M mono version coming after looking at the F5M earlier in the year.  Otica / XTreme sensitivity makes this stuff very interesting to consider.  The price is a no-brainer.

This is what they will look like.

[jmimac351]

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[jmimac351]

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[Jaytor]

My F5Ms have prodigious bass performance, but I think power supply capacity has a lot to do with how well an amp can deliver bass. This could potentially be a problem with the F5M Redux since there is no local energy storage and the external SMPS supplies may have limitations on much much instantaneous current can be delivered. We'll have to wait for more people to build it and report.

[jmimac351]

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[Jaytor]

The ACA is designed to run on a single power supply rail so needs both input and output coupling capacitors. It is also designed to be as inexpensive as possible so the quality of the parts is not very high. The quality of the capacitors can have a significant effect on the sound quality.

The F5M has no capacitors except in the power supply. No capacitors is always better than even the highest quality caps.

I did use good quality Vishay Dale resistors, but I think the quality of the resistors is secondary to the better topology of the F5M, lack of capacitors in the signal path, and better power supply.

[mkrawcz]

I built 2 F5Ms. The first with just cheap resistors, the second with Vishay resistors. I noticed no difference in sound quality. That’s the beauty of the F5. Other than the FETs, there is only a couple resistors in the signal path and nothing else. The ACA is not even a comparison as that is a very high distortion amp that was designed as an easy project to get peoples feet wet in DIY. The F5M is a very different animal.

[jmimac351]

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[mkrawcz]

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? 

All First Watt models are limited production runs. Generally, once those sell out and the parts for those amps can still be acquired, Papa will release the amp designs to the DIY community. The J2 was an exception to the limited run rule for a long time due to the overwhelming demand for it. Now that the production run for that one is over and the last units have been sold, I expect the J2 to become a DIY build pretty soon. Someone already brought it up and Nelson hinted at it. At any rate, all of Nelsons best stuff gets released to DIY eventually as long as it can still be built.

[BrandonB]

I am finally finished (at least for now) with my new preamp build. I started this project almost three years ago, and have built five different circuits for the tube line stage - the first two being John Broskie's Aikido designs, and the last three being my own designs.

Jay your builds are super impressive.  I just need to know now where to send my order....lol.
P.S.  I actually got my bike out and road it today for the first time in about a year.