Yes I realise I wasn't helping with the OT so apologies from me and I shall leave it here.
Just to say I had my last RS delivery last week with those RS/talema trafos and in the box was a flyer to say they are changing to DHL imminently. Maybe that has changed things for you. But I can't fault the service from RS.
Just to say I had my last RS delivery last week with those RS/talema trafos and in the box was a flyer to say they are changing to DHL imminently. Maybe that has changed things for you. But I can't fault the service from RS.
Salas,
I am looking at a new amp, due to a feedback loop the input impedance is 10k or a little less.
Can the DCG3 drive that kind of load?
Rush
Finally done!
I started talking about my build plan back in January. It's taken a bit longer than I had hoped, but partly because I was waiting for the Ultrabib boards to become available, and then I was in the middle of a couple of other projects.
I finally finished wiring everything up today, and amazingly, everything worked the first time.
My build is a two chassis design with a separate enclosure for the transformer and first stage power supplies (rectifiers and CLC filtering). The main chassis contains a balanced relay-switch input selector feeding a balanced buffer which drivers the relay-switched attenuator. The input select and attenuator are from Khozmo. Four channels are used for fully balanced operation.
The output of the attenuator feeds a pair of DCG-3 2-channel boards, one used for each channel for fully balanced operation, as well as an AMB A24 line stage. The latter is used to provide a single-ended output to drive my subwoofer.
The Khozmo attenuator has an OLED display and remote control for volume and input selector. The rotary encoder used to control volume doubles as a sequential input selector - pushing in the volume knob selects the next input. The remote also allows volume and input selection.
I'm using a total of eight SSLV1.3 UltraBib regulators to supply +/- 12V and +/- 17V separately for each channel. The lower voltage regulator supplies the AMB A24 boards.
The image below shows the backpanel and separate power supply chassis sitting on top.
The power supply chassis contains a custom Toiroidy 400VA transformer that has separate secondaries for the +/-12V and +/-17V supplies for each channel, plus the +5V supply for the switch attenuator (a total of nine secondaries).
I'm using a Neurochrome soft-start board which provides for a low-voltage lighted vandal switch for power control.
Four linear power supply boards, each with 27,000 uF of filter caps provide the DC supply which feed the Ultrabib regulators in the main chassis. There is also a regulated 5V supply for the attenuator logic.
So far, I've only connected to the junky speakers I have for testing in my workshop, so I haven't heard what it can sound like yet. I have to reconfigure my audio rack in my main system to make room for two boxes before I can really hear what it can do. Stay tuned.
I started talking about my build plan back in January. It's taken a bit longer than I had hoped, but partly because I was waiting for the Ultrabib boards to become available, and then I was in the middle of a couple of other projects.
I finally finished wiring everything up today, and amazingly, everything worked the first time.
My build is a two chassis design with a separate enclosure for the transformer and first stage power supplies (rectifiers and CLC filtering). The main chassis contains a balanced relay-switch input selector feeding a balanced buffer which drivers the relay-switched attenuator. The input select and attenuator are from Khozmo. Four channels are used for fully balanced operation.
The output of the attenuator feeds a pair of DCG-3 2-channel boards, one used for each channel for fully balanced operation, as well as an AMB A24 line stage. The latter is used to provide a single-ended output to drive my subwoofer.
The Khozmo attenuator has an OLED display and remote control for volume and input selector. The rotary encoder used to control volume doubles as a sequential input selector - pushing in the volume knob selects the next input. The remote also allows volume and input selection.
I'm using a total of eight SSLV1.3 UltraBib regulators to supply +/- 12V and +/- 17V separately for each channel. The lower voltage regulator supplies the AMB A24 boards.
The image below shows the backpanel and separate power supply chassis sitting on top.
The power supply chassis contains a custom Toiroidy 400VA transformer that has separate secondaries for the +/-12V and +/-17V supplies for each channel, plus the +5V supply for the switch attenuator (a total of nine secondaries).
I'm using a Neurochrome soft-start board which provides for a low-voltage lighted vandal switch for power control.
Four linear power supply boards, each with 27,000 uF of filter caps provide the DC supply which feed the Ultrabib regulators in the main chassis. There is also a regulated 5V supply for the attenuator logic.
So far, I've only connected to the junky speakers I have for testing in my workshop, so I haven't heard what it can sound like yet. I have to reconfigure my audio rack in my main system to make room for two boxes before I can really hear what it can do. Stay tuned.
I don't have the equipment to do an FFT analysis at this point. Given the number of DIY builds I've been doing, this is something I need to rectify. I realize it's not that difficult.
My DAC (Denafrips Terminator Plus) doesn't have an output buffer after the resistor ladder and, as such, has a fairly high output impedance. I wanted to use a lower impedance attenuator in this build and, at the same time, increase the input impedance.
Edit: Also provides a nice single-ended to balanced conversion for the RCA inputs.
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Thanks for the suggestion. I've run across this product before. Seems like they aren't taking orders at this point. I'll try to remember to keep an eye on it.
Many tubeheads traditionally don't like the sound of output buffer (cathode follower). I wonder if your DAC's designers used to be tubeheads in a former life.
By the way, DCG3 doesn't have an output buffer as well. A succinct two stage all fets circuit.
Its output topology is Class A single ended common source Mosfet cascode voltage amplifier.
Can be affected for OLG by very heavy loading vs three stage with source follower buffer, but obviously not when in line level duty.
This kind of output stage doesn't lose phase margin to tend unstable even on very long or parallel output cables driven capacitance.
I installed my preamp in my main system today. It took some juggling since I had to move my audio server out of the rack to make room for the two-chassis preamp.
It's only got about two hours of play time so far, but it's sounding pretty sweet. What's interesting is the bass is noticeably more authoritative. My main speakers roll off around 50 Hz or so and the subs connect to the A24 buffer, so I'm not sure how much of this is the DCG3 provide better mid-bass, the significantly improved power supplies, the much higher preamp input impedance, or different (and lower value) resistors in the attenuator. At any rate, very happy so far.
It's only got about two hours of play time so far, but it's sounding pretty sweet. What's interesting is the bass is noticeably more authoritative. My main speakers roll off around 50 Hz or so and the subs connect to the A24 buffer, so I'm not sure how much of this is the DCG3 provide better mid-bass, the significantly improved power supplies, the much higher preamp input impedance, or different (and lower value) resistors in the attenuator. At any rate, very happy so far.
Well, its a complex configuration to clearly know what section does better for what system component.
Its significant that your elaborate preamp build worked straight away without any technical problem in some of its subsystems and it sounds very good to you. Congratulations. Did we mention before it looks very nice? We surely did. Especially now it's on a rack. Tomorrow you will know even more about the system's sonic signature changes. It usually takes a couple of days to sink in.
Its significant that your elaborate preamp build worked straight away without any technical problem in some of its subsystems and it sounds very good to you. Congratulations. Did we mention before it looks very nice? We surely did. Especially now it's on a rack. Tomorrow you will know even more about the system's sonic signature changes. It usually takes a couple of days to sink in.