As mentioned in #4855 I have finally completed the lid for my DCG3 preamp.
No it does not feature a kangaroo ventilation cut out or XXXX beer tins but it does feature native Australian timbers: the dark red is Jarrah Eucalyptus Marginata, and the pale insert is Sheoak Casuarina sp. with its decorative grain.
This preamp with the FSP has brought vinyls head and shoulders above CDs, and even the CDs sound good.
Thank you once again Salas.
Graeme
No it does not feature a kangaroo ventilation cut out or XXXX beer tins but it does feature native Australian timbers: the dark red is Jarrah Eucalyptus Marginata, and the pale insert is Sheoak Casuarina sp. with its decorative grain.
This preamp with the FSP has brought vinyls head and shoulders above CDs, and even the CDs sound good.
Thank you once again Salas.
Graeme
Attachments
One of the most aesthetically characterful DCG3 builds posted here. Graeme, you are welcome and congratulations for your efforts.
*Last point of concern is if the bottom chassis metal is massive enough to absorb most heat or bottom & back panel ventilation openings are needed so to keep the internal temperature adequate. For many years of carefree operation in hot Australia.
*Last point of concern is if the bottom chassis metal is massive enough to absorb most heat or bottom & back panel ventilation openings are needed so to keep the internal temperature adequate. For many years of carefree operation in hot Australia.
Good point. I will need to address the ventilation issue, particularly as this unit is located over the class A power amp - not much of an issue at the moment as it is winter but of real concern when summer comes around with our temperatures running to 40C+.
Graeme
Yet another one
My DCG3 preamplifier is finally brought to life. Covid-19 delayed the project for 6 months. I was waiting 4 months for UBIB regulators alone, stuck somewhere and there were delays with other parts as well.
This one is made for preamplifier duties. It is a proper A class SE preamplifier in categories of bias current, dissipation and weight: 0,15 A, 34 W, 10 kg.
PS is dual mono with UBIB shunt regulators. Having to dissipate 30 W inside preamplifier case didn’t seem good idea so I decided for 2U Dissipante case meant for amplifiers. This proved to be a good match as heatsink temperature rise is only 8 to 10 C above ambient and for PS capacitors up to 15 C.
UBIB regulators do exhibit voltage drop with temperature rise so voltage drops 0,5V from initial 17 V but regulators are surprisingly consistent. All four regulators differ less than 10 mV over wide temperature range.
AS for noise or hum, there is nothing to write about. This thing is absolutely dead silent with no input signal and volume to the max. Nothing to hear or measure.
I decided to make my own input selector as nothing readily available was to my liking. Final version will use Muses volume control and there is IR receiver along with LED display. That was first reason to have window at front plate and display was an afterthought.
So far posted DCG3 builds helped me greatly to decide how will I build my own so I hope that some useful idea can be found here as well.
My DCG3 preamplifier is finally brought to life. Covid-19 delayed the project for 6 months. I was waiting 4 months for UBIB regulators alone, stuck somewhere and there were delays with other parts as well.
This one is made for preamplifier duties. It is a proper A class SE preamplifier in categories of bias current, dissipation and weight: 0,15 A, 34 W, 10 kg.
PS is dual mono with UBIB shunt regulators. Having to dissipate 30 W inside preamplifier case didn’t seem good idea so I decided for 2U Dissipante case meant for amplifiers. This proved to be a good match as heatsink temperature rise is only 8 to 10 C above ambient and for PS capacitors up to 15 C.
UBIB regulators do exhibit voltage drop with temperature rise so voltage drops 0,5V from initial 17 V but regulators are surprisingly consistent. All four regulators differ less than 10 mV over wide temperature range.
AS for noise or hum, there is nothing to write about. This thing is absolutely dead silent with no input signal and volume to the max. Nothing to hear or measure.
I decided to make my own input selector as nothing readily available was to my liking. Final version will use Muses volume control and there is IR receiver along with LED display. That was first reason to have window at front plate and display was an afterthought.
So far posted DCG3 builds helped me greatly to decide how will I build my own so I hope that some useful idea can be found here as well.
Attachments
While assembling the preamplifier I tested output with no plate between PS and preamplifier circuit. There was no audible difference. Transformers used are “audio grade” meaning that they are shielded among other better properties vs standard toroids.
Other important point is that audio ground is lifted from the chassis and mains ground with “ground loop breaker” circuit and that all grounds converge to star point at that GLB circuit. This all is probably not needed but is good to have if you want to be sure there will be no hum.
Other important point is that audio ground is lifted from the chassis and mains ground with “ground loop breaker” circuit and that all grounds converge to star point at that GLB circuit. This all is probably not needed but is good to have if you want to be sure there will be no hum.
Not only a clean build but with interesting heavy duty configuration also. A customized arrangement nonetheless. Congratulations tombo56.
UBiBs behave as expected. Negative Vout drift is normal by their Vref design until they settle. The final Muses attenuation solution is surely going to sound different than the ALPS Blue used for now. On what system are you listening to it and does it make a good first impression?
P.S.
Do the double parallel outputs have some series buffer resistors on the back panel selector/direct connection boards?
UBiBs behave as expected. Negative Vout drift is normal by their Vref design until they settle. The final Muses attenuation solution is surely going to sound different than the ALPS Blue used for now. On what system are you listening to it and does it make a good first impression?
P.S.
Do the double parallel outputs have some series buffer resistors on the back panel selector/direct connection boards?
Yes. It makes a very good first impression and it was listened only through headphones. I am not yet in position to listen it properly on true high end system but I laid out my plan.
I call my circumstances “terribly fantastic” because I’m returning to DIY audio after long pause and have to build everything from the scratch. Preamplifier is among first components to build. Imagine how much fun awaits me in building all needed components (that’s fantastic) and how terrible is to not yet have complete system.
There are no resistors in the output path. Among others, I’ll have to drive amplifiers with transformers as VAS in front of big SIT with high Ciss so DCG driving capacity is very useful.
I call my circumstances “terribly fantastic” because I’m returning to DIY audio after long pause and have to build everything from the scratch. Preamplifier is among first components to build. Imagine how much fun awaits me in building all needed components (that’s fantastic) and how terrible is to not yet have complete system.
There are no resistors in the output path. Among others, I’ll have to drive amplifiers with transformers as VAS in front of big SIT with high Ciss so DCG driving capacity is very useful.
Thanks Salas, I’m actually not sure what my initial setting is and I have enough resistors to play with. Your manual is always at hand on the pad...thank you for these excellent documentation’s, that come along with you projects!
So here is the back... I will change the power inlet to a fixed cable. And the little heatsink deserves his second screw!
So here is the back... I will change the power inlet to a fixed cable. And the little heatsink deserves his second screw!