Teabag, I noticed back in post 582 someone noted that "wirewound resistors usually avoided because of their inductance." This is in reference to R13 and R14. I notice your BOM specifies a wirewound resistor, (of very high quality) and its data sheet does state it is non-inductive. I am assuming that if this was a problem you would not have used it. On the contrary, I do have a bunch of the Panasonic Blue 3 watt .47 ohm resistors usually called for. I have already installed the wirewound you listed:
WNDR50FET Ohmite | Mouser
i'm sure I am being overly careful, and this wirewound is fine here?
Russellc
WNDR50FET Ohmite | Mouser
i'm sure I am being overly careful, and this wirewound is fine here?
Russellc
Generally, I find this particular brand and part to be well constructed and has lower PPM than the metal oxide types of resistors. To me, lower ppm parts generally have a more appealing and direct sound to them, if one believes they can hear such things. Of course they have lower thermal drift in their value as well.
Yes, it had considerably better specs. Like I noted I assumed it was fine and already installed it. Just an abundance of caution is all!
It's alive. I fired up my new M2 this afternoon and everything went without a hitch. I had to do some head scratching on V+, V- and ground, it has been awhile since I built a Firstwatt. Lately I have been building SET's but it came back to me. I used Grimberg's boards and Jfets from our store that I had already bought months ago. First impressions are very positive. I could not zero the DC offset exactly to zero but what little remained was so small as to be insignificant. No turn off turn on pops and absolutely quite on my very efficient horns. No shielding is needed of the input transformer in my build and my case is a very small one I built using heat sinks I purchased separately and making the case. Hats off to Grimberg for making the boards and a bow and salute to Nelson for his generosity making this amp available for Diyer's. More listening impressions after I get a few hours listening over the next few days. First impression is a fantastic amplifier with no gremlins whatsoever.
Congratulations Wdecho
Could you please share your subjective M2 amp appreciation with different styles of the music :
rock, jazz, electronic, big symphonic and small classic ensembles ?
This amplifier are polyvalent or very great on acoustic bands ?
Have a nice day
Attachments
Congratulations Wdecho
Could you please share your subjective M2 amp appreciation with different styles of the music :
rock, jazz, electronic, big symphonic and small classic ensembles ?
This amplifier are polyvalent or very great on acoustic bands ?
Have a nice day
I need a few hours and days to do an proper assessment of the sound compared to my other amps. My very first thought was I would not be able to tell if my best SET was playing or this amp. I have not A/B'ed it with any of my other amps yet so I am reluctant to say much more. I did listen some last night and it does sound fantastic with my horns. I am using a very simple tube pre amplifier design I built with what some would consider good amounts of 2nd harmonics. As most of us know the best amplifier is the one for our own personal speakers. Amps that sound great with conventional speakers will not sound the same with horns. This amplifier, as Nelson has said, is especially nice with horns from my very short listening period.
I thought all I needed was the back panel kit to complete my M-2. Chassis arrived yesterday. Back panel kit is "out for delivery today." Now, Going through all my boxes of parts, I dont have any CL-60 on hand. While not exactly proper, I guess I can ground power supply through an appropriate resistor temporarily, and fire up with a variac. CL-60 on order...
Russellc
Russellc
The M2 boards replaced some SE BA3 boards. I have built 4 FW clones with just 2 cases. This is the neat thing about FW's being able to try different Class A circuits without having to spend more money on new cases and PS sections. I now have a complete F6 and M2. I do not see replacing either of these boards. Both are keepers as is. My next FW build will be from scratch. As for the sound of the 4 I have built, I can compare it to sex. "The worse I ever had was just simply wonderful."
I inquired to Jason and he responded favorably to offering the heatsink only with the standard Diystore pattern drilled and tapped. All my amps at the end of the power supply go to two row terminal blocks, then on to the amp. All I would have to unsolder is at the RCA jacks and the speaker posts. Then remove heatsink amp and all to set aside.
New heatsink with amp already bolted to them would then be installed, screwed to the terminal block. Then attach inputs and outputs to speaker for a quick change out.
I have built F-5, F-6 BA-3 and now doing M-2 but all in their own chassis so far. The F-5 was done with heatsinks and 1/8 inch 6062 aluminum sheet. Very strong, but all that drilling and tapping was very hard on my old hands. No matter how careful I was, little aluminum curley ques were everywhere for weeks! I find these cases very nice in that regard, but as always, convenience costs money...always.
I think I am done for a while, but I just contacted Spencer about Jfets for two BA-3 boards to build BBA-3 balanced monoblocks and have most of the parts, no counting 2 more 5U chassis to house them.
Before doing that, I am going to build the Pumpkin-Shunty kit I got from ZenMod some time ago. Start with the power supply. If that runs properly, then the preamp section, Pumpkin. Assuming all goes well with it, then the BBA-3 monoblocks.
Russellc
New heatsink with amp already bolted to them would then be installed, screwed to the terminal block. Then attach inputs and outputs to speaker for a quick change out.
I have built F-5, F-6 BA-3 and now doing M-2 but all in their own chassis so far. The F-5 was done with heatsinks and 1/8 inch 6062 aluminum sheet. Very strong, but all that drilling and tapping was very hard on my old hands. No matter how careful I was, little aluminum curley ques were everywhere for weeks! I find these cases very nice in that regard, but as always, convenience costs money...always.
I think I am done for a while, but I just contacted Spencer about Jfets for two BA-3 boards to build BBA-3 balanced monoblocks and have most of the parts, no counting 2 more 5U chassis to house them.
Before doing that, I am going to build the Pumpkin-Shunty kit I got from ZenMod some time ago. Start with the power supply. If that runs properly, then the preamp section, Pumpkin. Assuming all goes well with it, then the BBA-3 monoblocks.
Russellc
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Now that is seriously good news! Having a lot of 1/4" & 3/8" alloy sheet, making a case will be very simple indeed. They'll be heavy mind!
Thank you a lot for this Russell.
Well it is not done or anything, he did state it was a very good suggestion. If you go to "commercial" forums, to chassis discussion, it is there
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