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Cantilope

First Watt Clone - The DIY M2

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First Watt Clone - The DIY M2 is a class A amp that follows Nelson Pass's design and tries to clone his work.  NP is a big supporter of DIY and released this schematic recently.  As I already own 2 M2s, I built this to run my center channel K402 bi-amped.

 

The completed tested and working AMP:

post-8016-0-09280000-1459093079_thumb.jp

 

I have never built anything like this before and if not for Wdecho, not sure I would have attempted to.  With his guidance and help in parts selections and oversight during the build he managed to help me build this from afar without me electrocuting myself.  I want to share my experience with you, to encourage you to try and build a SS amp or tubes or line stages whatever.  If I can do it, so can you.  To start I suggest having a nice soldering iron.  I bought a Hakko for this build and have no regrets, part of my success is good clean soldering.

 

Below is what I spent, I spared no expense (but didn't spend a fortune either) and ended up with a nice quiet AMP.

 

Budget:

 

M2 Boards - $28

(2) M2 TF Edcore - $22

FWPS 400 18v TF - $65

Case - $480

Small Parts - $125

 

Total = $720

 

Audio Boards

 

http://www.diyaudio.com/forums/group-buys/286699-gb-pass-m2-clone-boards-120mm-ums-spacing-tea-bag.html

 

PS Printed Board

 

http://diyaudiostore.com/collections/printed-circuit-boards/products/universal-psu

 

Case

 

http://diyaudiostore.com/collections/dissipante

Edited by Cantilope
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post-8016-0-70320000-1459093848_thumb.jp

 

Here you can see the parts laid out on my table, and this is everything for an M2. First step is to create the power supply.  The First Watt M2 requires 50V DC to run the audio boards.  In order to take 120V AC and turn it into DC you need the big toroidal Transformer and the bridge rectifiers from there it feed the Power Supply board which takes the DC and stores some and smooths out the DC signal.

 

post-8016-0-17520000-1459093983_thumb.jp

 

Here you can see the Power Supply boards are complete and mounted in the case.  You can also see the black and red twisted wires in the block, thats where the switch ties in.  The wires in my hand get plugged into the switch on the case. 

 

post-8016-0-08200000-1459094519_thumb.jp

 

This is a photo of the PS complete.  At this point I plugged it in and had 51.6V.  I used a light bulb wired into the plug circuit to act as a circuit breaker to prevent a melt down if I had a direct short.  The light turns on if there is a direct short rather than spark and short.

Edited by Cantilope
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post-8016-0-68760000-1459095057_thumb.jp

 

Here I am assembling the Audio Boards.  The little tester allows me to test every part before it goes in.

 

post-8016-0-60680000-1459094971_thumb.jp

 

In this photo you can see the populated Audio Boards ready to be installed.  (I actually have 2 pairs here for 2 stereo AMPS).  The photo of the completed amp with an open top is in the first post.

 

post-8016-0-18640000-1459095263_thumb.jp

 

Here is the front, nice clean brushed aluminum finish and matches my NP built M2s.

 

post-8016-0-85520000-1459095196_thumb.jp

 

Here is the final photo, what seems funny to me is the lack of warning and caution stickers missing from the back.  No one is there to tell me not to stick my hand in it...

 

With this AMP there is one small easy adjustment at the end for the DC offset.  Very easy to do.  I very much enjoyed the making of this amp and it will not be my last project.  In fact I doubt I will ever purchase a manufactured amp unless there is a specific need for it.  The sound quality is amazing on my Jubes and I highly recommend the First Watt M2 amp, or better yet build your own.

 

Joe

 

(Wdecho - this is as much your project as it was mine, please feel free to post and comment and clarify this thread).

Edited by Cantilope
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I had read a quote where NP said the M2 circuit is not his favorite for use with high sens horns in that it is noisy. Do you find this to be true, you haven't mentioned an issue and seem quite happy with the results. I was actually very close to pulling the trigger on an M2 until I read the NP comment where I backed off.

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Not to argue but what I read on audio asylum - quote from NP "M2 is definitely the noisiest available from FW at 500uV. Put this amp on 100db speakers and you will hear it". It was that comment only that had me re-think the purchase.

He goes on to talk about the effect autoformers has on this in picking up field noise from a near transformer.

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Joe, you did a beautiful job with the amp!  Having good support is always helpful, and William is unquestionably the "go-to" person for expertise on builds like this.  You are very fortunate to have had him at your virtual elbow!   Keep up the terrific work!!!

 

Maynard

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Great looking amp. Did it come in kit form or did you have to round up parts based off of a schematic?

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First Watt Clone - The DIY M2 is a class A amp that follows Nelson Pass's design and tries to clone his work.  NP is a big supporter of DIY and released this schematic recently.  As I already own 2 M2s, I built this to run my center channel K402 bi-amped.

 

The completed tested and working AMP:

 

 

I have never built anything like this before and if not for Wdecho, not sure I would have attempted to.  With his guidance and help in parts selections and oversight during the build he managed to help me build this from afar without me electrocuting myself.  I want to share my experience with you, to encourage you to try and build a SS amp or tubes or line stages whatever.  If I can do it, so can you.  To start I suggest having a nice soldering iron.  I bought a Hakko for this build and have no regrets, part of my success is good clean soldering.

 

 

 

 

Excellent job on the M2 build.  At some point, the M2 is on my “audio bucket list” to build.  I heard one briefly when I bought my J2 so I picked up the boards and autoformers during the group buy to add to my parts bin. Interesting concept applied with the M2 using the input autoformer as the gain stage in that it seems like Nelson does something similar to the step-up transformer used as a gain stage for a moving coil cartridge.  I see he gets 15dB of gain using the autoformer.

 

 

 

 

Not to argue but what I read on audio asylum - quote from NP "M2 is definitely the noisiest available from FW at 500uV. Put this amp on 100db speakers and you will hear it". It was that comment only that had me re-think the purchase.

He goes on to talk about the effect autoformers has on this in picking up field noise from a near transformer.

 

Cantilope did say in one of his conversations with me that he thought maybe the M2 he just built is quieter than the 2 production ones he bought. It may be because of the size of the case. Perhaps the Firstwatt case is a little bit smaller making the input transformers closer to the PS transformer. I have LaScala's that are like 103db speakers and my M2 is quiet. Nelson may just being safe in case someone does complain about a touch of noise when you are a foot from the speaker with no music playing. I can stick my ear right on the horn, nothing, but I am almost 67 and I am sure my hearing is not as good as my Grandsons. I have one that complains that the dog whistle hurts his ears every time I use it. Most hear nothing from a dog whistle. 

 

The M2 is considered one of the best sounding FW amplifiers with horns along with the F3 and newer SIT amplifiers.

 

I have heard Nelson say the F5 with bright speakers is like instant coffee in the microwave in the morning but there are members here that like the F5 with their horns. A lot depends what you are expecting from your speakers. The F5 probably has more detail, I have not heard one. I have not considered building one because of what Nelson had to say about it but then I may like the F5 if I were to build one. The F6 is a very revealing amplifier with some of the best detail you will find in an amp. It is not my favorite amp with my horns in my room A very good amp but not my favorite. The M2 has a more SET sound that I find attractive. 

 

 

 

I have to think in most situations the level of noise will be inconsequential.  At 500uV the amplifier is injecting 500 microvolts (or ½ millivolt) of noise into the speaker.  With 103dB speakers, one watt into an 8 ohm load is 2.8 volts.  The math will show that 500uV is 75dB below 2.8 volts.  Therefore, the amplifier would introduce approximately 28 dB (103dB – 75dB) of noise (SPL) from your speakers.

 

In a quiet room with no music playing, one of those rooms where you can hear 10dB of noise from a pin dropping, using very high efficiency speakers greater than 100dB I can see how some people can probably slightly hear the amplifier.  However, there are many things that impact ambient noise levels in a house or apartment that are louder; such as someone starts to whisper (30dB), the refrigerator kicks on (50dB), someone starts taking at a conversational level (60dB), among many other things that impact the ambient noise levels. 

 

While I suspect some can hear the noise in certain situations, I’m sure others cannot (especially that person that lives in a city apartment where the ambient noise levels tend to be much higher).  In comparing the M2 with the J2 (I purchased) using my Klipschorns, while I did not experience any annoying hum, I had suspected that the level of noise may have been part of what I perceived as a slight masking of the musical detail as opposed to listening with the J2 that had the type of liquid clarity in the very fine musical details that was more in line with what I was looking for.

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While I suspect some can hear the noise in certain situations, I’m sure others cannot (especially that person that lives in a city apartment where the ambient noise levels tend to be much higher).  In comparing the M2 with the J2 (I purchased) using my Klipschorns, while I did not experience any annoying hum, I had suspected that the level of noise may have been part of what I perceived as a slight masking of the musical detail as opposed to listening with the J2 that had the type of liquid clarity in the very fine musical details that was more in line with what I was looking for.

 

You are correct sir, and this best sums up my thoughts...  I can hear the amps if they are on and the room is quiet and I am right up with my ear in the horn.  However, I like so much of the other things about the M2 that this is insignificant to me at this time.  However, I have read exactly what you have written about the J2 vs the M2 and I would be curious to hear one in my setup.

 

It does seem that mine is quieter, I have to climb right into the horn to hear anything, and I agree that's probably due the larger case and better separation.  When I say climb into the horn, these are K402s so I am being literal.

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While I suspect some can hear the noise in certain situations, I’m sure others cannot (especially that person that lives in a city apartment where the ambient noise levels tend to be much higher).  In comparing the M2 with the J2 (I purchased) using my Klipschorns, while I did not experience any annoying hum, I had suspected that the level of noise may have been part of what I perceived as a slight masking of the musical detail as opposed to listening with the J2 that had the type of liquid clarity in the very fine musical details that was more in line with what I was looking for.

 

 

You are correct sir, and this best sums up my thoughts...  I can hear the amps if they are on and the room is quiet and I am right up with my ear in the horn.  However, I like so much of the other things about the M2 that this is insignificant to me at this time.  However, I have read exactly what you have written about the J2 vs the M2 and I would be curious to hear one in my setup.

 

It does seem that mine is quieter, I have to climb right into the horn to hear anything, and I agree that's probably due the larger case and better separation.  When I say climb into the horn, these are K402s so I am being literal.

 

 

 

That's great and "needing to climb into the horn" to detect the noise (I understand the literal aspect you outline because I've had my Jubilees for five years now, Khorns for a much longer time) was essentially what I was trying to describe with my mathematical analysis of 500uV of noise, also outlined in that post; and how the noise level generated (at the speaker, not the listening position) from that level of voltage was already much lower than the typical day-to-day noises that already contribute to the ambient noise level in many houses and apartments.   

 

Since there had already been a couple of comments regarding the noise level of the amp that people had read about on other forums, I tried to put it into some context in relation to the various noise levels that most people are familiar with and demonstrate how little noise is actually there through mathematics, without suggesting specific conclusions, but thinking that the readers questioning the noise level would come to the realization that at the listening position, any noise from the amp is essentially non-existent.  I hope that the analysis hasn't been misunderstood by those reading the thread and further contribute to some of the confusion where people have been thinking the amp is too noisy for horns. 

 

Now that you have built one First Watt clone (since we all like to spend other people's money on this forum), if, or should I say when, you are up for a "different" build, I would suggest the Aleph J in order to sample a First Watt single-ended class-A two stage design that will match up very nicely to a larger variety of speakers as opposed to one of the other more esoteric single-ended, single gain stage designs where it becomes very difficult, if not impossible, to source certain parts. 

 

The "hard to get" Aleph J parts (circuit boards; transistor kit including 8 - IRFP240 N Channel Mosfets, 2 - ZTX550 & 4 - ZTX450; and 2 matched pairs LSJ74 JFETS for the differential amplifier gain stage) all can be bought at the diystore, there is a well-documented "6L6" build guide for the Aleph J on the diyaudio forum (at link below), and in some respects, the J2 is kind of like the JFET output transistor update of the Aleph J design. 

 

http://www.diyaudio.com/forums/pass-labs/241729-aleph-j-illustrated-build-guide.html

 

 

.

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I've built a Aleph 30 which can be converted fairly easily to the Aleph J by changing the front end transistors to the jfets. It is a very nice amplifier with some outstanding treble. It was the first FW clone I built. It is a good choice with our horns. 

 

 

The way you have been cranking out the builds, it may not be too long before you have sampled the entire portfolio of amplifiers.  :emotion-21:  Of course, my thought is that a person can never have too many amplifiers.  B) 

 

With that said, have you given any thought to building a F4 at some point and drive it with one of your single-ended tube amplifiers or even using a bi-amp set-up as Nelson Pass describes in the schematic below where the single-ended tube amplifier drives the mid/tweeter directly and drives the F4 that in turn drives the woofers? 

 

A single F4 will give 25 watts (50 watt peak) per channel into 8 ohms and 40 watts into 4 ohms. However, wired as a mono block the F4 will give 100 watts.  Essentially, one way to think about the F4 is as a refined power follower, it will essentially push the same voltage out that you send into it, but it will feed much more current through the load than the SET amp, if, or when, needed.

 

I see this same concept of tube for voltage gain and solid state (usually mosfets) for current used in some of the high-end headphone amps too. 

 

In another set-up I have I essentially use my DHT SET amplifier as the "voltage gain stage" directly into the F4 and because the F4 is such a simple Push-Pull circuit with no feedback, very low distortion levels and only a miniscule 50uV noise level, a lot of the characteristics of the DHT SET amp that I find very favorable will come through. I like to think of it kind of like a "SET on steroids" in some ways, but also noting that it looses only some very small aspect of that intimacy that DHT SET can provide in those near-field lower-level listening sessions.

 

On an important side note, there are various implementations of "adaptors" out there as the DHT SET output will need to be adapted to the RCA input of the F4.  Also, due to the F4's high input impedance (47,000 ohms), a resistor (~ 20 ohm, 5 watt resistor, but some have used anywhere from about 15 ohm - 22 ohm depending on how they like the sound) is needed across the SET outputs since the SET only "sees" the F4 and not the speakers.  On DHT SET amps with multiple taps (i.e. 4, 8 or 16 ohm) there seems to be some diversity on which tap sounds best; however, I suspect that is more related to system synergies.

 

 

F4 bi-wire.jpg

Edited by Fjd

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Now that you have built one First Watt clone (since we all like to spend other people's money on this forum), if, or should I say when, you are up for a "different" build, I would suggest the Aleph J in order to sample a First Watt single-ended class-A two stage design that will match up very nicely to a larger variety of speakers as opposed to one of the other more esoteric single-ended, single gain stage designs where it becomes very difficult, if not impossible, to source certain parts. 

 

The "hard to get" Aleph J parts (circuit boards; transistor kit including 8 - IRFP240 N Channel Mosfets, 2 - ZTX550 & 4 - ZTX450; and 2 matched pairs LSJ74 JFETS for the differential amplifier gain stage) all can be bought at the diystore, there is a well-documented "6L6" build guide for the Aleph J on the diyaudio forum (at link below), and in some respects, the J2 is kind of like the JFET output transistor update of the Aleph J design. 

 

http://www.diyaudio.com/forums/pass-labs/241729-aleph-j-illustrated-build-guide.html

I had to make an order to the DIY store for some other items, I went ahead and added this in the order.  It was only like $65. 

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post-8016-0-10660000-1461181962_thumb.jp

 

Went ahead and ordered the Aleph J parts and another case.  Here she is almost complete.  I have tested the Power Supply and am getting the anticipated voltage.  I'll post another once I get my last parts in and it wired up.

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Sorry I'm late to this thread

I also have the Teabag M2 DIY kit with his power boards ( @wdecho ) roped me into it :ph34r: late in the piece and I was lucky to get the whole kit after the group buy finished

Big parts are ordered  - 5U Deluxe Case with rear connection kit but they are still in transit for a few more days

I was also fortunate to have sourced two types of transistor kits 

Kit 1 - All Fairchild & Kit 2 Harris / Vishay

 

Currently I am very very carefully selecting the components now to populate the boards

I note that your total cost to build is less than me purchasing chassis - Currency exchange and transport ect  bump the price up 2.5 fold +

 

Living in hope that I don't go over $1800 AU

 

FR

 

 

 

 
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I have a question

What make, brand, type of resistors did you use on R1,2,3,4

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I will use Panasonic for the 3 watt

And for R1,2,3,4 - for dark background and warmth I am using non magnetic Audio Note Tantalums

The rest is made up of Military Vishay and BOM recommendations

Custom made 500 V GOSS ring shielded Toroidal from Harbuch

A few other enhancement goodies in the power supply

Edited by Full Range
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Full Range,  if your ever up to the task of building your own chassis.  There is a heat sink company there in Australia, I bet shipping wouldn't be so bad.   One of the forum members at diyaudio.com used them and had great results.

 

http://www.conradheatsinks.com/welcome.htm

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