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GB Pass M2 Clone Boards with 120mm UMS spacing by Tea-Bag

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A

aradan

Member
Joined 2015
I have finality got to my M2 boards and I have a question

8af657545590e183bc63d8c75db339b9.jpg


The bom states that R10 and R12 are optional and working as replacement for R8 and R9

However in all pictures of the builds I can see that all four resistors R8, R9, R10, R12 are populated.

I am building it using Harris units from this GB, so should I be populating all four as well?

Thanks :)

Sent from my ONE A2003 using Tapatalk
 
V

vvs07

Member
Joined 2011
Paid Member
aradan said:
I have finality got to my M2 boards and I have a question

8af657545590e183bc63d8c75db339b9.jpg


The bom states that R10 and R12 are optional and working as replacement for R8 and R9

However in all pictures of the builds I can see that all four resistors R8, R9, R10, R12 are populated.

I am building it using Harris units from this GB, so should I be populating all four as well?

Thanks :)

Sent from my ONE A2003 using Tapatalk
Click to expand...

I populated all four R8, R9, R10, R12. I also had to put 52K R7 in place of 47K to manage the negative offset. This amp sounds terrific.
 
Tea-Bag

Tea-Bag

Member
Joined 2006
Paid Member
Just to note, there is another GB that I have open for these boards. I want to get to 25 sets before I close it up to keep the costs the same. So please sign up on the spreadsheet if your interested. The link to the spreadsheet sign up is in my signature.
 
R

Russellc

Member
Joined 2003
Paid Member
Tea-Bag said:
Just to note, there is another GB that I have open for these boards. I want to get to 25 sets before I close it up to keep the costs the same. So please sign up on the spreadsheet if your interested. The link to the spreadsheet sign up is in my signature.
Click to expand...

Looks like we are at 19 or so...if you like First Watt amps, you need to get on the train....one of the very best here. Plus, these boards are primo, fit the pre drilled Diystore sinks perfectly, and the output devices are the bomb!:)

Russellc
 
B

Bare

Member
Joined 2001
Hmm... I'm keen on the M2 or at least was :eek:
What is this Amp like in direct Comparison to an F6 ?
Arguably a predecessor design from Nelson.. but the optocoupling is intruiging
I'm also asking.. as my F6 is Dead quiet .
And I mean absolutely noiseless !
Ear to the dust caps of My Tannoy Golds and I have had to check and see if the pesky F6 was powered up. IMO a More than merely 'Nice' attribute.
Consequently I'm Not so eager to build something that produces less than that.. results.
Am I expecting too much ? Or is the M2 stone /dead Silent as well ??
 
Last edited:
Tea-Bag

Tea-Bag

Member
Joined 2006
Paid Member
Bare said:
Hmm... I'm keen on the M2 or at least was :eek:
What is this Amp like in direct Comparison to an F6 ?
Arguably a predecessor design from Nelson.. but the optocoupling is intruiging
I'm also asking.. as my F6 is Dead quiet .
And I mean absolutely noiseless !
Ear to the dust caps of My Tannoy Golds and I have had to check and see if the pesky F6 was powered up. IMO a More than merely 'Nice' attribute.
Consequently I'm Not so eager to build something that produces less than that.. results.
Am I expecting too much ? Or is the M2 stone /dead Silent as well ??
Click to expand...

I will take a shot at this.
The F6, depending on the input transformer used, and the output devices used will present a substantially different sound.

The SemiSouth outputs in an F6 will present a cleaner sound, and the input transformers influence is easier to determine. In my setups, The jensen had a more ethereal and potentially detailed sound, and the Cinemag high nickel version had a more powerful and intense sound to it. Neither were neutral sounding. The Onetics transformer sounded neutral.

The IRFP240 output devices give the F6 a more golden sound. Kind of a more Dynaco pentode tube sound if you will. It makes it harder to determine input transformer's influence.

In the M2,
You give away some some nuanced sound, for a much more neutral sounding amplifier. It also has a more powerful and dynamic sound to it. Its a very relaxing amp to listen to it. It does not sound like your giving up much detail with this setup. It has maybe a little more impact and dynamic sound than the M2, but it sounds to me more neutral and impactful. I like what it can do to the top end, mid end and low end. I personally had some glare with the Vishay IRFP9240 output devices. I found the IRFP9240 output devices to have no glare. I have not done any other tweaks to the M2. Usually I am motivated to try for more, but I am so happy with it now it remains my main office amplifier where I end up spending a lot of time during the working hours myself. The only time I got any noise out of the M2 is when I did not shield the input wires. After doing that, all was good.
I think one other builder who used dual mono power supplies had some grounding issues, but these are common amplifier building issues, nothing probably unique to the M2. I did not need to shield the input transformers on either the F6 or M2.

My 2c
Tea
 
R

Russellc

Member
Joined 2003
Paid Member
Good comparison, Tea. The F6 is a very nice amp. I like M2 better. Most everyone who has both likes the M2 as fav. Again, both are fantastic amps. Both good bass, F6 more top end detail dominate (in comparison), M2 very relaxing, plenty of transparency, plenty of bass. Superb. No negatives to M2. transformers are very cheap, low parts count on boards.

My F6 is mosfet. My M2 uses Tea's optional mosfets, much recommended. Teabag's boards are very nice. No Firstwatt fan should be without this one.

All these amps are very, very nice...just in different ways. M2 is very special.:2c:

Russellc
 
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T

timmyjones

Member
Joined 2016
Hi everyone,
just signed up on your GB sheet for this build. Hope it's ok. If so, I can pay via paypal.
By the way, I am relatively new here at diyaudio, and also very inexperienced with diy electronics compared to you guys. So there is a risk that I may have to bother you a tiny bit throughout my build with surprisingly stupid questions.
 
Bangla H

Bangla H

Member
Joined 2013
Hi everyone.
After reading here and Official M2 schema thread a bit i also must!! buy a set of the
nice tea bag boards. I am on list GB#2.
Very good information in blog, also BOM list, all what is needed there. Excellent.

What about to say about use more expensiv transformer- Jensen Cinemag- very different in much better detailed sound/clearness....?
I also know if Mr.Pass have worked it out with this it is all good.

Regards Bangla.
 
Tea-Bag

Tea-Bag

Member
Joined 2006
Paid Member
Bangla H said:
What about to say about use more expensiv transformer- Jensen Cinemag- very different in much better detailed sound/clearness....?
I also know if Mr.Pass have worked it out with this it is all good.

Regards Bangla.
Click to expand...

See my earlier post regarding the matter via comparison to the F6.

I imagine Nelson did try different transformers before settling on an inexpensive edcor. It does just work. I would be tempted to try a Cinemag myself, but I am so happy with the current tone, I do not feel inclined to do so.
I would mention more about the above, the F6 is a great tweakers amp, the M2 runs good out of the box. It responds well I think to a few minor part changes, but nothing crazy. I would be more tempted to see if I can sneak some tone changes out of the 10uf cap, but I have not heard back from anyone that it is a must do.
 
T

timmyjones

Member
Joined 2016
Hi Tea-Bag, as mentioned I signed up on your GB list. I just wondered if you could confirm that it was ok that I joined before I went ahead and ordered the other parts.
Another thing, when ordering the parts from Spencer at fetaudio, I just send him an email to the address listed at his site, correct?
 
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