problem to take picture,,no working camera
have tried different grounding,,
ground from pre to rca output
no ground from Salas supply
in same boks are supply to dac and to waveio board
tried with an without ground from supplyes no different
hum is same on both channel
is nearly the same with low and high volume
have tried different grounding,,
ground from pre to rca output
no ground from Salas supply
in same boks are supply to dac and to waveio board
tried with an without ground from supplyes no different
hum is same on both channel
is nearly the same with low and high volume
Maybe try with a mobile phone? A picture would really help. Same buzz with low and high volume hints to a ground loop has been created within the various systems in the combo box. Also measure AC mV on the PSU rails to make sure its not an oscillation either.
I also have an idea about separating the ground lane on the preamp board between channels. But it will need a cut with a hobby knife. So we better see the build and catch something incompatible with the wiring first if it exists.
I also have an idea about separating the ground lane on the preamp board between channels. But it will need a cut with a hobby knife. So we better see the build and catch something incompatible with the wiring first if it exists.
Hi Salas
you have right with taking a picture ---but your idea to thing in other grounding solve the problem..totally noise free
it was my Sowter trafo from output of my dac,,they were grounded to the start point..i tried to remove the wire and that help..i think the problem with them was .they are not isolated from the kabinet
thanks Salas to help me on the right track
now i am waiting for my to trafoes from Poland. so i can mount the hole thing in a fine way
you have right with taking a picture ---but your idea to thing in other grounding solve the problem..totally noise free
it was my Sowter trafo from output of my dac,,they were grounded to the start point..i tried to remove the wire and that help..i think the problem with them was .they are not isolated from the kabinet
thanks Salas to help me on the right track
now i am waiting for my to trafoes from Poland. so i can mount the hole thing in a fine way
yes Salas always great with good idea
i can already now hear a difference to my AMB supply,,little to early to tell what i hear..must first give the supply some hours to play..
Keremito:::you can have right what you say about the bass from the pre with the Salas supply
it is early in the start of the supply and pre for you but i can hear that the bass (compared to my AMB supply) is so strong and not so round ,,it can sound like the bass is not there
but,,,this is some of the best bass heard in my system,,fast dry dynamik
i think you will discover that the sound settle a little down in the top when you have play some more hours on this pre
i can already now hear a difference to my AMB supply,,little to early to tell what i hear..must first give the supply some hours to play..
Keremito:::you can have right what you say about the bass from the pre with the Salas supply
it is early in the start of the supply and pre for you but i can hear that the bass (compared to my AMB supply) is so strong and not so round ,,it can sound like the bass is not there
but,,,this is some of the best bass heard in my system,,fast dry dynamik
i think you will discover that the sound settle a little down in the top when you have play some more hours on this pre
If there is no practical error involved in Keremito's and its only down to quality of bass maybe repositioning his speakers could be also considered as a test. A standard DCG3+DCSTB build presents bass through speakers more like planar headphones do. No bloat is there in the phrasing and suddenly it can slam like a garage door startling you. I would still recommend to him good quality short coaxial wiring though because its 1MHz capable preamp and RFI could go into it when simply using CAT-5 thinning its tone out.
Thank you Salas. Here are the measurements:
Resistor values while on the board: Left/Right
R12: 1mohms/1mohms
R13: 0.585 mohms/0.585 mohms
R14: 10 kohms/10 kohms
R15: 50 ohnms/50 ohnms
Q1 collector: 12.66/12.74 Volts
Q2 collector: 16.58/16.61 Volts
J3 drain: 400 mV/275 mV
J3 Vgs: 1.014/1.003 Volts
I think all is good, I removed the CAT6 wires used 18 ga shielded for the inputs, changed the volume pot to regular fit now while the Goldpoint arrives. With new cheapo pot get loud with less rotation. Old was 20k, the one in use is 50k. I ordered 25k, hopefully it will be ok.
I also put the preamp on the scope, all good consistent gain of 3 20-100 Hz.
The system is very resolving, I have 2 sources, one being a Sony HAP-Z1ES, with it some recordings are on the bright side. Plenty of detail, good sound stage. Not so good recordings just sound like that.
Resistor values while on the board: Left/Right
R12: 1mohms/1mohms
R13: 0.585 mohms/0.585 mohms
R14: 10 kohms/10 kohms
R15: 50 ohnms/50 ohnms
Q1 collector: 12.66/12.74 Volts
Q2 collector: 16.58/16.61 Volts
J3 drain: 400 mV/275 mV
J3 Vgs: 1.014/1.003 Volts
I think all is good, I removed the CAT6 wires used 18 ga shielded for the inputs, changed the volume pot to regular fit now while the Goldpoint arrives. With new cheapo pot get loud with less rotation. Old was 20k, the one in use is 50k. I ordered 25k, hopefully it will be ok.
I also put the preamp on the scope, all good consistent gain of 3 20-100 Hz.
The system is very resolving, I have 2 sources, one being a Sony HAP-Z1ES, with it some recordings are on the bright side. Plenty of detail, good sound stage. Not so good recordings just sound like that.
I am happy to report that bass is back. I think that the volume attenuator was the culprit, it measures well through all the rotation tracking was very good, perhaps I had it miswired, who knows it's out now. I am waiting for a new high-grade pot. I will report what becomes of the DCG3 with a high grade attenuator. Thanks to all for the help! I am smiling again!
I am happy to report that bass is back. I think that the volume attenuator was the culprit, it measures well through all the rotation tracking was very good, perhaps I had it miswired, who knows it's out now. I am waiting for a new high-grade pot. I will report what becomes of the DCG3 with a high grade attenuator. Thanks to all for the help! I am smiling again!
Congratulations!!!
Tarnished switch pot contacts most probably. The 25k Goldpoint you expect has no harsh or thin traits. It also opens up volume in slower fashion than most 21-24 step switchers. Even if you will need more output impedance from it so to round off your sound further we can always up R1. No worries.
I had listened to the first beta tester's two realizations with a mono BiB for both channels and they were generally fine. For subjective details between using those PSUs its precarious to say much because I had listened with them in different builds. It takes to have two double mono DCG3 preamps with BiB/DCSTB using exactly the same parts everywhere from trafos, diodes, reservoir capacitors types, down to same volume pots, resistors, and wiring/grounding scheme, to truly can sit down and compare in strict A/B fashion.
Just because its a revealing hard driving preamp with gain and much line output current capability, I designed and tested the fixed parts and fixed voltage DCSTB along with it to secure an author tested easy solution that plays well together. For you guys to can start confidently by avoiding speculation, too much heat build up, more external sinking, or potential for setup and stability errors with general duty variable PSU tryouts depending on type. If already in hand from previous projects its painless to try them. But sometimes they can be costly enough new experiments to risk subjective disappointment especially when investing in double mono.
From there on you may experiment according to your curiosity. The preamp's electrical needs are not weird demanding only one certain PSU. Beardman for instance applied three different PSUs already during his saga to fit the sound hand in glove for a particular system. Two highly respected third party ones from the kits/modules market and the DCSTB.
Most valuable subjective finding in this thread is have patience. If your build does not mix and match perfectly well within an existing setup on first shot don't despair. Leave it powered on for some hours, play again to make sure of your goals, and start trying things. Its worth the effort as it proved again and again. New bold gear can be upsetting an existing system's balance sometimes or there is an influential internal part to better manipulate or fix.
Keep it at +/-17V. There is a three Leds drop to the relay calculated for giving it 12V on nominal rails (that can be changed to less Leds if the preamp MUST be used with lower voltages if the HP output max power does not matter to you). But the capacitive parasitics of the Mosfets are better on the higher voltage rails so the THD and the speed aspects fare better.
Those are healthy results and you also stated that after changing a dubious volume pot the bass feels normal again. This build behaves and reacts well then.
There is no basic assembly error indication. But I forgot to ask you the DC mV across R3 also. Let me know those R3 voltage drops when its handy to measure.
Thanks
How is it going in the meantime? Did you let it rest waiting to be boxed or you clocked some further music replay time with it?