I have the ones from post #2: http://www.diyaudio.com/forums/attachments/swap-meet/15569d1065019964-75-parts-sale-not-only-b2.jpg
I got the 600VA transformer in the mail yesterday, and I had time to get it installed today. I changed the rectifiers from MUR860's to some 50A chassis mount bridges because they were running really hot and there wasn't a very convenient way for me to sink them. I ended up with about .2v of voltage drop without a load connected to the PS compared to the MUR860's, 25v instead of 25.2.
I measured the rails with the amp boards connected and I have about 22.2v, lower than I expected, but it seems to be operating just fine, no more mechanical buzzing or excessive heat from the transformer so I'm happy.
And the sound is just fantastic, I don't like describing sound, but in my opinion, it easily beats a gainclone and is very smooth like a SET tube amp. Really makes my little Wharfedale Diamond 8.2's sound much bigger than they are. The amp feels a lot more powerful than the 25w on the spec sheet would suggest, I'm very pleased!
Listening to Rodrigo y Gabriela 11:11 on it right now.
A couple obligatory pics..
I measured the rails with the amp boards connected and I have about 22.2v, lower than I expected, but it seems to be operating just fine, no more mechanical buzzing or excessive heat from the transformer so I'm happy.
And the sound is just fantastic, I don't like describing sound, but in my opinion, it easily beats a gainclone and is very smooth like a SET tube amp. Really makes my little Wharfedale Diamond 8.2's sound much bigger than they are. The amp feels a lot more powerful than the 25w on the spec sheet would suggest, I'm very pleased!
Listening to Rodrigo y Gabriela 11:11 on it right now.A couple obligatory pics..
Attachments
I love a happy ending.
Congratulations, it looks sensational too.
It sure does encourage me to finish mine.
Congratulations, it looks sensational too.
It sure does encourage me to finish mine.
Not sure what it 'should' be but most Pass designs are running over 100,000uf. Maybe its a different animal and does not need that though.
Uriah
Uriah
Thanks for the clarification. Didn't want to make a mistake. lol.
Still trying to find a PS schematic that I want to use.
James
According to the service manual, most of the Firstwatt designs use 120,000uF for a stereo amp. I would probably use double that ammount.
I'm thinking I might bump up the cap sizes in my amp, 47000uF 35v Panasonic T-HA will fit Peter's power supply board.
If at all possible, try using a bank of capacitor for each channel.
You could use stand offs to put another capacitor bank on top of your existing one.
You could use stand offs to put another capacitor bank on top of your existing one.
Maybe get another power supply board form Peter D.
I always like the result of having an independent power supply per channel.
I always like the result of having an independent power supply per channel.
I was kicking around that idea as well, I should have enough vertical room to stack them
Than,
So would the PS schematic listed on page 15 of http://www.firstwatt.com/downloads/f4_om.pdf be a goo fit for a mono X-J?
Speaking of whitch. Peter I know you have been busy with your phono stage but have you had time to test the X circut?
Also just throwing this out there, but there have been concerns that using 5 of these amps for my HT might cause issues in the room with ambiant heat. What do you all think?
So would the PS schematic listed on page 15 of http://www.firstwatt.com/downloads/f4_om.pdf be a goo fit for a mono X-J?
Speaking of whitch. Peter I know you have been busy with your phono stage but have you had time to test the X circut?
Also just throwing this out there, but there have been concerns that using 5 of these amps for my HT might cause issues in the room with ambiant heat. What do you all think?
I intend to use the attached scheme as my PS but would like to exclude the 1.8mH
Attachments
I got the 600VA transformer in the mail yesterday, and I had time to get it installed today. I changed the rectifiers from MUR860's to some 50A chassis mount bridges because they were running really hot and there wasn't a very convenient way for me to sink them. I ended up with about .2v of voltage drop without a load connected to the PS compared to the MUR860's, 25v instead of 25.2.
I measured the rails with the amp boards connected and I have about 22.2v, lower than I expected, but it seems to be operating just fine, no more mechanical buzzing or excessive heat from the transformer so I'm happy.
And the sound is just fantastic, I don't like describing sound, but in my opinion, it easily beats a gainclone and is very smooth like a SET tube amp. Really makes my little Wharfedale Diamond 8.2's sound much bigger than they are. The amp feels a lot more powerful than the 25w on the spec sheet would suggest, I'm very pleased!
A couple obligatory pics..
Are those ebay heatsinks? How warm do they get?
Has anyone completed an Aleph J-X? Pics 😀
That should be ok, but if it was me I would probably double the amount of capacitance.