Thanks SKA76 & MagicBus. The small black box beside the DCG3 is the Dac I use (Schiit Bifrost). The wooden box in the middle of the photo is the Salas 6V6 pre and the two metal boxes on either side of the 6V6 pre is the Salas FSP phono (separate PSU and RIAA). The BiFrost is ok but what i'm finding is that because I have to share the small basement room with low ceilings with the wife's large craft table, the acoustics are sub-optimal and limiting. But it is enjoyable none the less. For now the DCG3 is in the system and I'm liking what I'm hearing.
An Ultra FSP-phono is eventually going to be made at some point, as well as the Ultrabib DCG3 version. Eventually I'll build a music server based on the RPi4 & L-Adapter, (which i already have) so I can to remove the laptop for the digital front end. I just have to get the courage on how to install the software (picoreplayer i'm thinking). I'm not computer confident in terms of getting the RPI4 configured but learning this stuff out is half the fun.
Cheers
Frank M
An Ultra FSP-phono is eventually going to be made at some point, as well as the Ultrabib DCG3 version. Eventually I'll build a music server based on the RPi4 & L-Adapter, (which i already have) so I can to remove the laptop for the digital front end. I just have to get the courage on how to install the software (picoreplayer i'm thinking). I'm not computer confident in terms of getting the RPI4 configured but learning this stuff out is half the fun.
Cheers
Frank M
Yes, indeed it is a journey with a lot to learn and fun along with some (sometimes not so pleasant) surprises. For me it is pretty much like cooking according to a recipe as I do not have the technical background to completely understand what I am doing.
Salas´ preamp design is very resolving in my almost complete DIY set (apart from the SBT and DAC) and I am still flabbergasted how close it comes to when compared with using the DAC. When listening now through my CD collection it is almost like listening to different recordings. I can hear now details that previously were just some suggestions somewhere hidden in the background/probably subconsciously outlined but I never really could hear them.
Still also have parts for Salas´ phono stage waiting to be assembled “at some point”.
Best of luck with the new projects.
Salas´ preamp design is very resolving in my almost complete DIY set (apart from the SBT and DAC) and I am still flabbergasted how close it comes to when compared with using the DAC. When listening now through my CD collection it is almost like listening to different recordings. I can hear now details that previously were just some suggestions somewhere hidden in the background/probably subconsciously outlined but I never really could hear them.
Still also have parts for Salas´ phono stage waiting to be assembled “at some point”.
Best of luck with the new projects.
Last edited:
I just reconnected everything and switched it on!
All seems pretty good, after some 15 minutes, the heatsink close to the mosfets(?) rose ~5°C.
Offsets are 0-1mV (the channel that always was good) and +2/-2 mV DC on the other channel …
Will give it an ear full and make pictures this afternoon.
All seems pretty good, after some 15 minutes, the heatsink close to the mosfets(?) rose ~5°C.
Offsets are 0-1mV (the channel that always was good) and +2/-2 mV DC on the other channel …
Will give it an ear full and make pictures this afternoon.
Re previous posting #6606 on heat sink, I manage to use an old power amp HS and drill 6 holes on the base .. and it came out OK. So I am deploying a oversize HS.
Anyway I just finished populating the DCG3 board and 1 DCSTB (the other one is missing a part that Teabag had it in the mail). I have tested the single ( I separated it ) DCSTB and the output voltage is 17v plus. My question is can I used the single DCSTB to test the DCG3 board 1 channel at a time ?
Anyway I just finished populating the DCG3 board and 1 DCSTB (the other one is missing a part that Teabag had it in the mail). I have tested the single ( I separated it ) DCSTB and the output voltage is 17v plus. My question is can I used the single DCSTB to test the DCG3 board 1 channel at a time ?
You have one +17V/0/-17V DCSTB section ready you mean? Unless you will bridge it over to DCG3's both power input connectors, the preamp PCB will not power up fully because one connector feeds the output relay circuit too, the other one feeds the U1 DC servo chip too. Which are commonly serving each audio channel.
Another vote for the BC-327-40 !!! Easy to substitute in with the female pin guides as supplied in Tea's kit. For my system a clearer presentation and slightly better instrument separation with nicer low level detail. The difference is not huge in my system compared to the BC-550 but the BC-327-40 is not coming out.
Thanks guys !! (Salas and Tea)
FM
Thanks guys !! (Salas and Tea)
FM
Hi Salas,
You have one +17V/0/-17V DCSTB section ready you mean? Yes.
Ok, I will wait for the part to arrive & complete the other DCSTB & then do the final testing. But thanks for the reply. At this stage, I want to make sure everything is hookup correctly, then I will take my time to look for a proper enclosure.
For the time being, I am using a single 160VA 15-0-15 toroid transformer for this project. It is rated @ 117v and my average household AC is 122.5 volt. I might have a 18v transformer in storage which I intend to use if everything works out.
You have one +17V/0/-17V DCSTB section ready you mean? Yes.
Ok, I will wait for the part to arrive & complete the other DCSTB & then do the final testing. But thanks for the reply. At this stage, I want to make sure everything is hookup correctly, then I will take my time to look for a proper enclosure.
For the time being, I am using a single 160VA 15-0-15 toroid transformer for this project. It is rated @ 117v and my average household AC is 122.5 volt. I might have a 18v transformer in storage which I intend to use if everything works out.
15-0-15 at 122.5 primary will surely put out a little more plus its big 160VA core will not lose any output under just preamp load. It will do ok.
But a thing is its not advisable to share common secondaries between two bridge rectifiers. Each DCSTB section has one made from discrete diodes after its AC input. Sharing can possibly give rise to a hum loop.
But a thing is its not advisable to share common secondaries between two bridge rectifiers. Each DCSTB section has one made from discrete diodes after its AC input. Sharing can possibly give rise to a hum loop.
Hi Salas,
I got the missing pair of 5102 from Tea today and installed on the second DCSTB board .. the output reads -17.53 & +21.8 DC, the LED on the +side is a lot brighter. I remember seeing the same problem somewhere in this thread, but I can't find it. Can you give me some advise. Thanks.
Tom
I got the missing pair of 5102 from Tea today and installed on the second DCSTB board .. the output reads -17.53 & +21.8 DC, the LED on the +side is a lot brighter. I remember seeing the same problem somewhere in this thread, but I can't find it. Can you give me some advise. Thanks.
Tom
Absolutely right, always try ordering two secondaries instead of center taped, gives you more options and you might use them with synchronous rectifiers as well @luckydork
Try same for the primaries. Having two 115V gives you to option to connect them in parallel for the US or in series for Europe. It is just more universal, should you decide to swap or sell the amp later on.
I think I will do some update on the uneven output voltage; +21.7 -17.5 (with15v dual output transformer)
After consulting with Teabag, I replace the bc550 and re-solder/reflow the + side of the DCSTB, but the problem didn't go away. Still the same voltage. During this process, I have a couple of blown fuse, probably because the center tap wire was loose. How critical was the fuse in this circuit as Tea was telling me it also act as a resistor? Right now, I am using a couple of .5 ma quick blow fuse, just to make sure that it that I still have the LCD working. I intend to put the proper fuse (.4 ma slow-blow) ASAP when the store open on Monday.
Other clarification : I had one mono DCSTB completed with the proper +/- 17 V. The above description refers to a second mono board. It was tested with no connection to the dcg-3 and no heat sink although j1 &2 was not warm even after 5 mins.
After consulting with Teabag, I replace the bc550 and re-solder/reflow the + side of the DCSTB, but the problem didn't go away. Still the same voltage. During this process, I have a couple of blown fuse, probably because the center tap wire was loose. How critical was the fuse in this circuit as Tea was telling me it also act as a resistor? Right now, I am using a couple of .5 ma quick blow fuse, just to make sure that it that I still have the LCD working. I intend to put the proper fuse (.4 ma slow-blow) ASAP when the store open on Monday.
Other clarification : I had one mono DCSTB completed with the proper +/- 17 V. The above description refers to a second mono board. It was tested with no connection to the dcg-3 and no heat sink although j1 &2 was not warm even after 5 mins.
Maybe the bigger transistor is blown at the positive side. Don't pull it from the PCB yet, set your DMM in diode mode, put the black probe to its base (pin 1) and touch its other two pins with the red probe one at a time. If it shows around 0.6V both way its good. If it shows OL or near zero V either way, a junction is open or shorted and needs to be replaced.
Hi Salas,
Forgive me for asking, not knowledgeable in this area especially trouble shooting:
Bigger transistor=MJE1530G ?
My DMM have V, A, Ohm mode but no diode mode. The way you describe the procedure, it seems to me I am measuring the voltage, so is it voltage mode? Power on?
Regards,
Tom
Forgive me for asking, not knowledgeable in this area especially trouble shooting:
Bigger transistor=MJE1530G ?
My DMM have V, A, Ohm mode but no diode mode. The way you describe the procedure, it seems to me I am measuring the voltage, so is it voltage mode? Power on?
Regards,
Tom