Power transformer blues?
Got these nice potted transformers - 50V, 2 x 18V
http://sg.element14.com/multicomp/mcfe050-18/transformer-50va-2-x-18v/dp/9531793
Tested the transformers without load - getting 19.45 VAC from input mains of 220 Volts. The input mains voltage goes up a bit at times to ~225 volts.
I see lot of the recent discussion on builds with lower voltage transformers... my trafos are ok for the build? I have also ordered the DCSTB power supply board.
Also saw that Tea-Bag is using 17V transformers in his build:
http://www.diyaudio.com/forums/blogs/tea-bag/1340-salas-dcg-3-preamplifier-dcstb-power-supply.html
Look forward to guidance from Salas and other builders. 🙂
Got these nice potted transformers - 50V, 2 x 18V
http://sg.element14.com/multicomp/mcfe050-18/transformer-50va-2-x-18v/dp/9531793
Tested the transformers without load - getting 19.45 VAC from input mains of 220 Volts. The input mains voltage goes up a bit at times to ~225 volts.
I see lot of the recent discussion on builds with lower voltage transformers... my trafos are ok for the build? I have also ordered the DCSTB power supply board.
Also saw that Tea-Bag is using 17V transformers in his build:
http://www.diyaudio.com/forums/blogs/tea-bag/1340-salas-dcg-3-preamplifier-dcstb-power-supply.html
Look forward to guidance from Salas and other builders. 🙂
"Extremely low radiated magnetic field, suitable for sensitive electronics"
That's positive
When off-load most transformers give bit more AC which is normal. No worries your transformers are fully compatible to this build and also look very good for construction and electrical spec.
That's positive
When off-load most transformers give bit more AC which is normal. No worries your transformers are fully compatible to this build and also look very good for construction and electrical spec.
Diode Connections.
Salas, thank you for answering my questions in post 1117.🙂
Reason I was asking about using PF5102s with higher than 8mA Idss is because I have quite a few matched pairs over 8mA.
Would the 33 ohm resistors have to be changed to use them?
Also, would someone please look at my diode connections below to see if they are correct?
I always seem to get those darn things connected wrong.😱
Salas, thank you for answering my questions in post 1117.🙂
Reason I was asking about using PF5102s with higher than 8mA Idss is because I have quite a few matched pairs over 8mA.
Would the 33 ohm resistors have to be changed to use them?
Also, would someone please look at my diode connections below to see if they are correct?
I always seem to get those darn things connected wrong.😱
Attachments
Are you making a DCSTB copy for your DCG3 or one to set differently for powering a different project?
If you want to keep about 5mA ref current make them something like 100 Ohm or more
Look at DCSTB board's photo in post#2 for bridge diodes orientations
If you want to keep about 5mA ref current make them something like 100 Ohm or more
Look at DCSTB board's photo in post#2 for bridge diodes orientations
The Multicomp transformers are what I have used in my build. Good quality and very quiet in use with this build.
Once I have boards made, I'll be using them for both the DCG3 and other preamps/buffers I build.
I've already looked at the photo in post 2. I'm trying to follow the board on the left.
I believe I've connected the same diodes with the top trace(blue in my photo) and lower trace as Tea, but I would like to make double sure before submitting any Gerbers.
Surely someone can verify if their correct. If not I can ask over in the PS forum.
Of course they are correct when two cathodes make a plus and two anodes make a minus in a bridge
More as a pre than HP; although if my good lady had her way it would be the other way round😉
I have managed a good few hours of listening in the past few days and the more I listen the more I am liking this pre 😀
Anyone building the DCG3 your ears are in for a treat.
I forget to follow 🙂 ... Enjoying my Pre. everyday...
First Pre. i ever finished without any hum at all... First Pre. i had with such stereo spread...
Wife using headphoneamp. part of it a lot !
Looking forward to pair it with some nice ClassA power soon (well within a month or two i think 😀)
Jesper.
Salas, I ordered a 20k smd stepper pot. Should be a week or two until I get it. I will hold my judgement until then but...this amp sounds very good at 150ma through headphones...better than I thought. Very dynamic and crisp. Leading edges are very sharp, but not harsh. Drum strikes crack and pop but vocals don't hurt. The tonality may change somewhat when I switch to a 20k pot.
For preamp use I don't have enough gain at 3x. It sounds good but I prefer the Ba-3 with more gain in my system. Iam using an f5 with only 15db of gain.
Is it possible to go above 4x gain? 15 to 20db is what I seem to like.
No problem with THD or phase margin when going further up like x6 (15.56dB) R6=2.5k R7 remains 499R. Or 7x (16.9dB) R6=3k R7 remains 499R. It just won't be alike in vol pot control range when using it in insensitive power amp + average sens speakers driving role and in some sensitive headphones driving role. Unless its a single purpose line pre role or the control has more resolution to can home in better (48 positions switch or a microcontroller based attenuator system).
True, Iam still trying to figure out what to use the dcg3 for...it's a nice headphone amp for sure, but to be honest I really don't like headphones that much and would much rather spend time and money tweaking my speaker system. Headphones are always a compromise for me...I just can't seem to enjoy them like speakers. And I have gone through enough headphones to know this.
I will increase gain, get a proper value pot, clean up some wiring and report back. I definitely hear something good...just got to get the gain figured out. I definitely hear differences between this pre and the pass BA-3, which is interesting. But I want to get the gain sorted for a proper comparison.
I will increase gain, get a proper value pot, clean up some wiring and report back. I definitely hear something good...just got to get the gain figured out. I definitely hear differences between this pre and the pass BA-3, which is interesting. But I want to get the gain sorted for a proper comparison.