Thanks ZM and 6L6. I want to raise my idle current from 1,5A to 1,8A thats why i was looking for more temperature headroom. I really like the idea of the babysitter...
I think i will also implement one of the juma cap mx versions to make some space in my small case. See attached picture of actual configuration. I want to switch to a horizontal mounted canned toroydi.pl transformer but the diyaudio universal psu is too big or my case is too small..
I think i will also implement one of the juma cap mx versions to make some space in my small case. See attached picture of actual configuration. I want to switch to a horizontal mounted canned toroydi.pl transformer but the diyaudio universal psu is too big or my case is too small..
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Generally speaking, the most pleasing distortion spectra is usually found at Nelson’s recommended bias.
do not forget that cap multiplier is not saving you from heat - you're just taking heat from output transistors and putting the same in multiplier transistors
there is all another set of reasons for using cap-multy, decreasing heat sum is not one of them
there is all another set of reasons for using cap-multy, decreasing heat sum is not one of them
I am using 2sk1529/2sj200 at the moment and most other users seemed to lower R13 and R14 to 0.22R or 0.33R (to be more beefy against heavy-to-drive loads like my 4-ohm speakers? But of course i can't explain why exactly). That would increase idle current to about 1.8A .
In the long term i also want to try the bigger brother 2sk1530 / 2SJ201 when i can afford them. Found some FQA19N20 / FQA12P20 also but i dont want to try them soon.
If i can find some IRFP9140 not made by Vishay or IR i would try and go back to "normal" configuration with recommended bias current. But I wasn't really satisfied using the Vishay IRFP240/9240 in the first place, the soundstage was too wide and mids and high a bit tamed (later i read about the funny frequency shelfing behaviour of some IRFP9240 devices, thats why i am looking for affordable Harris devices).
yeah that makes sense, silly me.. To be able to mount a toroidy.pl transformer is a better reason, isn't it?
In the long term i also want to try the bigger brother 2sk1530 / 2SJ201 when i can afford them. Found some FQA19N20 / FQA12P20 also but i dont want to try them soon.
If i can find some IRFP9140 not made by Vishay or IR i would try and go back to "normal" configuration with recommended bias current. But I wasn't really satisfied using the Vishay IRFP240/9240 in the first place, the soundstage was too wide and mids and high a bit tamed (later i read about the funny frequency shelfing behaviour of some IRFP9240 devices, thats why i am looking for affordable Harris devices).
yeah that makes sense, silly me.. To be able to mount a toroidy.pl transformer is a better reason, isn't it?
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nothing to have with Donut brand - all of them being made in adequate voltage
first reason - to get cleaner rails to amp
second reason - have that Donut on the shelf, rails highish, have heatsinking enough, let's get cleaner rails and to use already paid xformer
that's it, in short
first reason - to get cleaner rails to amp
second reason - have that Donut on the shelf, rails highish, have heatsinking enough, let's get cleaner rails and to use already paid xformer
that's it, in short
I am sorry for my bad english. The toroidy.pl thing was a kind of joke, it was about space and mounting position of the transformer. I would love to mount the transformer flat to the base plate instead of vertical.
Thank you for your reasonable answers. Between the lines i read
"if you want small heatsink take stock M2" and
"if you want to raise idle current (to use different output devices) aim for a bigger heatsink instead of a lower rail voltage"
Thank you for your reasonable answers. Between the lines i read
"if you want small heatsink take stock M2" and
"if you want to raise idle current (to use different output devices) aim for a bigger heatsink instead of a lower rail voltage"
Addi, any reason why you don't want to use the FQA12P20? IIRC, that and FQA19n20c
were the devices in the production M2.
were the devices in the production M2.
Some say that those Toshibas sound very musical compared to the FQA or IRFP devices. And i want to learn and fiddle around. But of course it is also a good idea to try "stock" configuration one day. It's just hard to decide what to try next... thank you all for your ideas.
Unless you have high ambient temps or desire dual mono, the smaller (4U) case works fine for my M2. (standard build, teabag boards). M2 is a little hotter than F6, which is the coolest of my clones. Not nearly as hot as AlephJ, which I also have in 4U size.
That said, the 5U case has so much more room inside, not to mention the increased heatsinking. If I had it to do over, I would do 5U size!
Russellc
Hi, i received some FQA19N20 and FQA12P20 and i am asking myself:
are my transistors-original or copy?
Please follow the link If you know how an original FQA19N20 looks like. Thank you 🙂
are my transistors-original or copy?
Please follow the link If you know how an original FQA19N20 looks like. Thank you 🙂
These are a couple of a batch that I bought 13 years ago from Mouser. Hope that helps.
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Thank you guys for your your help! I just had no other Fairchild Power MOSfet to compare. And i could not believe that there is still some new old stock of this around 🙂
Attila, they are from Darisus.
Attila, they are from Darisus.
yes, Darisus not Darsius.
mea culpa
the fairchild parts are working in my M2 and F5.
Can't hear any difference to IRFPs.
I like the longer pins which allow for higher standoffs.
Cheers
A.
mea culpa
the fairchild parts are working in my M2 and F5.
Can't hear any difference to IRFPs.
I like the longer pins which allow for higher standoffs.
Cheers
A.
I built an M2 some time ago using Tea-Bags M2 boards. It is a great amp but I have never fully got rid of some hum. I don't have this hum in my other First Watt builds.
I was thinking of trying switch mode supplies. Would a couple of Meanwell RPS-400-24 and Neurocromes Meanwell control (Mean Well Control: Power Your Audio Amp with Mean Well EPP or RPS SMPS – Neurochrome) be appropriate or are there other switch-mode supplies better/cheaper?
I was thinking of trying switch mode supplies. Would a couple of Meanwell RPS-400-24 and Neurocromes Meanwell control (Mean Well Control: Power Your Audio Amp with Mean Well EPP or RPS SMPS – Neurochrome) be appropriate or are there other switch-mode supplies better/cheaper?
I published some years ago when I built it. I did reduce the hum a lot at that time. I would just like it to be as quiet as my other amps. And I would like to try swich mode 🙂
I have no objection 🙂
can't help with switcher recommendation, not having experience with any exact commercial type, but I'm sure that Boyz will help
can't help with switcher recommendation, not having experience with any exact commercial type, but I'm sure that Boyz will help
You could try ACA power supplies - you'll need 2 to start with. Later on, you can add another 2 for dual mono supply.
There's no need for that addon control card, just unsolder the heatsink connection to 24V negative, see the arrow. Then you can connect them in series and have +24, common, and -24V.
There's no need for that addon control card, just unsolder the heatsink connection to 24V negative, see the arrow. Then you can connect them in series and have +24, common, and -24V.
