Can this be seen in a way analogous to how different DACs may produce different "flavours"?
Its not that subjectively effective but kind of subtle. Objectively contributes to the feedback node if inadequate enough. I could measure 6dB higher noise floor and somewhat higher third harmonic in the DCG3 if using a TL072 servo for instance.
Thank you Salas. So, the op amp is matched primarily to keep the distortion as low as possible rather than fine tuning to a certain "signature".
Probably already discussed elsewhere, but are there any other op amps that would be suitable for your design?
Many very low input current op-amps can do the job. JFET or MOS input types in other words. Must be described as unity gain stable, low noise, low offset, in the datasheet. Medium GBP & medium speed are usually safer for drop-in replacement.
Subjectively you may develop a bit of a preference between them but technically all with such spec will perform. There's an eight pin socket in the DCG3 to can easily service but to can also roll.
Subjectively you may develop a bit of a preference between them but technically all with such spec will perform. There's an eight pin socket in the DCG3 to can easily service but to can also roll.
Hi all,
I am in the process of building the dcg3/dcstb . I have a question about the heat sink for dcg3. Based on previous posting, flat metal bar is the most popular. Can someone tell me the source of this kind of heat sink ? I was thinking using 2 pieces .. 1 for each side which mean that I only have to align/drill 3 hole instead of 6 hole in a single piece. I don't have a drill press, only a regular hand-held one. I actually have a few normal heat sinks (fin), but for this project, I think a flat one is the most practical, especially if I mount the dcg3 board vertically. Any other suggestion is greatly appreciated. Thank you,
I am in the process of building the dcg3/dcstb . I have a question about the heat sink for dcg3. Based on previous posting, flat metal bar is the most popular. Can someone tell me the source of this kind of heat sink ? I was thinking using 2 pieces .. 1 for each side which mean that I only have to align/drill 3 hole instead of 6 hole in a single piece. I don't have a drill press, only a regular hand-held one. I actually have a few normal heat sinks (fin), but for this project, I think a flat one is the most practical, especially if I mount the dcg3 board vertically. Any other suggestion is greatly appreciated. Thank you,
Hello Salas + everyone, good afternoon!
Received a little batch of Q2 (bc550n).
According to the component tester, the removed Q2 seems to be gone...
Measured 2 new ones, they are in the range
hfE=500
Ie=2.7mA
Vbe=680mV
hfE=545
Ie=2.8mA
Vbe=674mV
What's to be searched for? (Couldn't find your description anymore, sorry!)
Received a little batch of Q2 (bc550n).
According to the component tester, the removed Q2 seems to be gone...
Measured 2 new ones, they are in the range
hfE=500
Ie=2.7mA
Vbe=680mV
hfE=545
Ie=2.8mA
Vbe=674mV
What's to be searched for? (Couldn't find your description anymore, sorry!)
Attachments
I set no specific hfe goal for the BC 5xxC transistors in the DCSTB psu. Your samples are fine high hfe examples.
Another datapoint , finished the dcg3 and it is now playing in the system. Previous pre is Salas 6V6 with sshv2.
Had to ground headphone jack and vol pot (goldpoint 25k v24 steps) to get rid of hum. Took me forever to figure that out after I ripped the whole system apart. Dcg3 has dstb power supply .
Power amps are Baby Huey el84 push pull and speaks are altec 414’s in onken box with altec 802 on top.
Early listening impressions are this thing is dead quiet!! Using bc550 so far. Can hear difference with recordings in regards to how good or bad they were recorded. Very smooth presentation, very relaxed, good separation of instruments and good sound at lower volumes.
6V6 preamp has more flesh and visceral presentation if that means anything but l’ve only had the dcg3 on for a few hours and it is opening up and bass is getting better. Have yet to put a cover on the dcg3
preamp but I couldn’t wait to see what it sounded like and I am happy.
Thank you Salas and Tea Bag, really enjoying this stuff. Still have the Ultrabib dcg3 version to build, perhaps with a much nicer enclosure that this pre deserves.
Had to ground headphone jack and vol pot (goldpoint 25k v24 steps) to get rid of hum. Took me forever to figure that out after I ripped the whole system apart. Dcg3 has dstb power supply .
Power amps are Baby Huey el84 push pull and speaks are altec 414’s in onken box with altec 802 on top.
Early listening impressions are this thing is dead quiet!! Using bc550 so far. Can hear difference with recordings in regards to how good or bad they were recorded. Very smooth presentation, very relaxed, good separation of instruments and good sound at lower volumes.
6V6 preamp has more flesh and visceral presentation if that means anything but l’ve only had the dcg3 on for a few hours and it is opening up and bass is getting better. Have yet to put a cover on the dcg3
Thank you Salas and Tea Bag, really enjoying this stuff. Still have the Ultrabib dcg3 version to build, perhaps with a much nicer enclosure that this pre deserves.
Very nice! Congratulations! You are welcome. An Impressive full diy system.
Immediate presentation differences between the 6V6 line pre and the DCG3 are mainly due to:
a. 5dB higher gain in the 6V6.
b. Less bandwidth in the 6V6 especially with 100k pot.
c. Better SINAD and no microphony in this FET design.
First and second can be tweaked closer between the two designs. Third parameter will remain superior with DCG3.
But it also depends on the power amps. How much of that extra resolution they pass through.
Immediate presentation differences between the 6V6 line pre and the DCG3 are mainly due to:
a. 5dB higher gain in the 6V6.
b. Less bandwidth in the 6V6 especially with 100k pot.
c. Better SINAD and no microphony in this FET design.
First and second can be tweaked closer between the two designs. Third parameter will remain superior with DCG3.
But it also depends on the power amps. How much of that extra resolution they pass through.
Very impressive and dedicated system! Can I ask what that small black box on the floor next to the DCG3 is?
Interfering here to say that I'm back in business.
just replaced the bc550n with an arbitrary one of the batch I received, PSU seems to be back in the nominals:
-17.35VDC / +17.4VDC, led bars engage with that little delay and shine parallel (equally bright as seen to my eyes)
so, on with the build, improve what can be done easily (HP-wiring for one, the cable I used first was much too stiff) and into the test-system for a very first listening impression!
just replaced the bc550n with an arbitrary one of the batch I received, PSU seems to be back in the nominals:
-17.35VDC / +17.4VDC, led bars engage with that little delay and shine parallel (equally bright as seen to my eyes)
so, on with the build, improve what can be done easily (HP-wiring for one, the cable I used first was much too stiff) and into the test-system for a very first listening impression!