Thanks for the pointers. I was already thinking of replacing the Darlington with a high Beta NPN; the 2SC3852 looks good here. Other recommendations will be tried as well.
I saved the earlier folders for the FE cards with the input rectifiers on the supply connector. My common drain amps are likely to run between 0V and –30V, so the ambidextrous power inlet may be very handy.
I saved the earlier folders for the FE cards with the input rectifiers on the supply connector. My common drain amps are likely to run between 0V and –30V, so the ambidextrous power inlet may be very handy.
Congratulations @ura1012 !! It sure looks like you did an excellent job building those Bulwark, Marauder, and Dreadnought boards. I think you'll really enjoy discovering their sonic similarities and differences, and I'm very glad you're able to listen to both categories of Front End board: without, and with, an Edcor step-up transformer.
Well done.
Well done.
Matched quad THF-51S on the shelf - Check. Bulwark and Dreadnaught kits order placed - Check. Is the
PSU filter board sold out in the store, or am I looking at the wrong thing?
The standalone PSU filter board that's sold out in the store, is discussed in this thread:
https://www.diyaudio.com/community/...all-warts-preamps-hpa-korg-nutube-etc.354213/
As post#1 of that thread says, it's designed to be used in line level equipment. Not power amplifiers. However if you do a little math on the rated output of your SMPS, which you intend to use for your VFET power amp, you may discover that TWO of those boards (one servicing the left channel, the other servicing the right channel) would operate within their spec constraints (current < 3 amperes) AND (voltage < 48 volts).
https://www.diyaudio.com/community/...all-warts-preamps-hpa-korg-nutube-etc.354213/
As post#1 of that thread says, it's designed to be used in line level equipment. Not power amplifiers. However if you do a little math on the rated output of your SMPS, which you intend to use for your VFET power amp, you may discover that TWO of those boards (one servicing the left channel, the other servicing the right channel) would operate within their spec constraints (current < 3 amperes) AND (voltage < 48 volts).
Disregard. I’ll follow your advice and will order from a PCB fab house.
Disregard. I’ll follow your advice and will order from a PCB fab house using the gerber files you have generously provided. Thanks!
I like the new names. These are familiar from reading history and watching many documentaries.
Several new circuit topologies are intriguing as well. I was in the midst of re-playing the set of M2x input stages after rebuilding my amp with a proper dual-mono power supply when the announcement was made. There is certainly some overlap between the two sets, but plenty of new material as well.
Several new circuit topologies are intriguing as well. I was in the midst of re-playing the set of M2x input stages after rebuilding my amp with a proper dual-mono power supply when the announcement was made. There is certainly some overlap between the two sets, but plenty of new material as well.
Bulwark board kit for sale. Received in December but I decided not to go ahead with it. In original box in perfect condition Al parts have been checked for values and quantity. And marked in the labels. Shipping by USPS priority which can be set at $10 in addition to the board price. $95.
Thanks for looking.
So what do you do when you have:
You make a preamp jig using VFET F/E cards for gain stages.
I used an Antek donut, Salas SSLV1.3 UltraBiB shunt regulator (positive rail only) set to 36V, eBay chassis, a selector switch, and Alps pot. This build also encouraged me to get a ferrule crimper. Why did I wait so long for that nice tool?
Bulwark is installed now, and it's sounding great into my Aleph 30 monos and JBL4410 monitors. Test music is Eilen Jewell. I would have finished this build last night, but I saw her play a fantastic set.
- One pair of front end PCBs in your VFET amp
- Other pair(s) idle on the shelf
- A second system in the house
- Some time to experiment
You make a preamp jig using VFET F/E cards for gain stages.
I used an Antek donut, Salas SSLV1.3 UltraBiB shunt regulator (positive rail only) set to 36V, eBay chassis, a selector switch, and Alps pot. This build also encouraged me to get a ferrule crimper. Why did I wait so long for that nice tool?
Bulwark is installed now, and it's sounding great into my Aleph 30 monos and JBL4410 monitors. Test music is Eilen Jewell. I would have finished this build last night, but I saw her play a fantastic set.
Attachments
Last edited:
I used 2R. Here is my logic.
I measured the current of the boards in my FET amp. These were the Marauders. I think I saw inrush of ~100mA, and steady state at 30 or 35mA. 100mA x 2 for inrush + 50 for Salas. 600/250 = 2.4R
I have a 2R/3W Panasonic in my stash. Close enough.
I didn't measure the "stock" board current or Bulwarks. I rolled the dice. I figure there's the inrush and 2R is well over for steady state. Everything worked perfectly on power up with no smoke, so I'll call it good.
I am late to the game. Life has been cruel these past years.
No quasimodo snubber though?
Not sure what's the purpose of these though. I am still catching up
BTW the gerbers on the first post do not include the diodes. At least the scourge and the bullwark which I checked. Unless my viewer messes up somehow
No quasimodo snubber though?
Not sure what's the purpose of these though. I am still catching upBTW the gerbers on the first post do not include the diodes. At least the scourge and the bullwark which I checked. Unless my viewer messes up somehow
Attachments
Great catch! The diodes were eliminated* in June of 2021, see post #141 of this thread for more discussion. The Gerbers and schematics attached to the first post, include this revision. And so do the boards+kits sold in the diyAudio store.
I'll attempt to eradicate mentions of the now-gone diodes, from the early post(s).
*for example, on the Scourge PCB they occupied the now-blank area to the left of the text "SCOURGE" in your plot of #317.
Last edited:
Gary,
All Aluminum amplifier chassis Hifi Enclosure preamplifier case 425x70x313mm
Seller: snjh1820
https://www.ebay.com/itm/353170288213
I kept the minimalist look with no markings on the selector switch. I have a 4 way switch, but only use 2 sources on this setup. If it's quiet - click, music, done....
For the volume knob I just took a punch and put a dot on it. Simple.
4 hours after building a Goldpoint attenuator arrived in the mail. Out with the Alps, in with the Goldpoint.
All Aluminum amplifier chassis Hifi Enclosure preamplifier case 425x70x313mm
Seller: snjh1820
https://www.ebay.com/itm/353170288213
I kept the minimalist look with no markings on the selector switch. I have a 4 way switch, but only use 2 sources on this setup. If it's quiet - click, music, done....
For the volume knob I just took a punch and put a dot on it. Simple.
4 hours after building a Goldpoint attenuator arrived in the mail. Out with the Alps, in with the Goldpoint.
