To get an idea what impact the filtering has, you could compare the sound with and without filter.
L2 needs to be temporarely replaced with 0.4 mH both channels for a flat response without treble rolloff correction.
When listening without filter, the whole filter with I/V must be completely removed and 100 ohm be used for I/V.
L2 needs to be temporarely replaced with 0.4 mH both channels for a flat response without treble rolloff correction.
When listening without filter, the whole filter with I/V must be completely removed and 100 ohm be used for I/V.
A higher R I/V gives a larger U out wich i need.
I like the tube output (sound)
With scope vieuws i have clock remains and wifi/dect/GSM/bluetooth rubbisch on the whole(very small and fast spikes). The last few years al that interference is gradually increased substantially.
Have still a hum have to figure that out first.
I like the tube output (sound)
With scope vieuws i have clock remains and wifi/dect/GSM/bluetooth rubbisch on the whole(very small and fast spikes). The last few years al that interference is gradually increased substantially.
Have still a hum have to figure that out first.
Oh yes and Bernard: the coils have unfortunately a ferrite core. I can wind some Mu-metal around the coils for screening.
Will turn some wooden or acryllic formers to wind new coils, preferably in a new I/V with higher R values and a steeper filter. Can i calculate the values myself?
I listened to a modified CD880 with clock and so on, and with measuring i had the same clock remains and interference problems (measured it with same scope) But the 880 did not sound as good as the diy player does with pcm56. I gues the tube output can handle rf better, and this could be the reason for better sound in non-os.
Will turn some wooden or acryllic formers to wind new coils, preferably in a new I/V with higher R values and a steeper filter. Can i calculate the values myself?
I listened to a modified CD880 with clock and so on, and with measuring i had the same clock remains and interference problems (measured it with same scope) But the 880 did not sound as good as the diy player does with pcm56. I gues the tube output can handle rf better, and this could be the reason for better sound in non-os.
I didn't say it before: Thanx Bernard for your I/V schematic with filter. Its sounding really good, the treble noise is gone here downstairs. (MLTQWT with old modded keflar tweeters from Focal).
The most obvious from the pcm56 is the naturalness of acoustic instruments like guitars. The strings allmost shimmer with good recordings. It's not fatiguing, bass is deep and contoured, sometimes little "whooly" I have a small peak in mids of my left speaker(couldn't solve that, tried everything) with good gear it is allmost gone, and now it is. The pcm gets the best out of it all. I like it, will buy a HT toroid transformer and put it all nicely together. The TDA can sound some "wild" sometimes, the pcm is more sophisticated. It sounds on low volume a very little bit dull, turn op the volume and a soundstage opens up...
The most obvious from the pcm56 is the naturalness of acoustic instruments like guitars. The strings allmost shimmer with good recordings. It's not fatiguing, bass is deep and contoured, sometimes little "whooly" I have a small peak in mids of my left speaker(couldn't solve that, tried everything) with good gear it is allmost gone, and now it is. The pcm gets the best out of it all. I like it, will buy a HT toroid transformer and put it all nicely together.
The TDA can sound some "wild" sometimes, the pcm is more sophisticated. It sounds on low volume a very little bit dull, turn op the volume and a soundstage opens up...
If you try to increase the output voltage by increasing the I/V resistors for a total of 450 ohm, L1 will be about 7.5mH which is very large for ironless coils.
It is better to increase current by paralleling 4 chips per channel.
My advice: try to get rid of the ferrite cores and the tube stage.
The tube will not make it any better, parallel chips will give you 0,5V and low output impedance. A transformer can boost it to 1V.
It is better to increase current by paralleling 4 chips per channel.
My advice: try to get rid of the ferrite cores and the tube stage.
The tube will not make it any better, parallel chips will give you 0,5V and low output impedance. A transformer can boost it to 1V.
I want to build a custom output for my pcm56 :
- volume control
- buffer output with maybe gain
- passive i/v
- some filter for 175khz sampling frequency (4xos)
I mesured my need : output impedance must stay around 0-800 ohm
Gain : I have a vague idea : with my power amp + 2 V max cd player I need -15 to - 65 db attenuation
i listen mostly to -35 to - 50 db...
Please help
- volume control
- buffer output with maybe gain
- passive i/v
- some filter for 175khz sampling frequency (4xos)
I mesured my need : output impedance must stay around 0-800 ohm
Gain : I have a vague idea : with my power amp + 2 V max cd player I need -15 to - 65 db attenuation
i listen mostly to -35 to - 50 db...
Please help
Hi Bernhard
The idea to use transformers as filter looks interesting. Do you think these tranformers can be used to filter NOS DAC? I do not need any gain as I use an active i/v stage with transistors.
Below are the specification for these transformers
Pri: ................ 600 ct, 150 Ohms.
Sec: .............. 600 ct, 150 Ohms.
Frequence: .... 30 Hz - 15 kHz.
The idea to use transformers as filter looks interesting. Do you think these tranformers can be used to filter NOS DAC? I do not need any gain as I use an active i/v stage with transistors.
Below are the specification for these transformers
Pri: ................ 600 ct, 150 Ohms.
Sec: .............. 600 ct, 150 Ohms.
Frequence: .... 30 Hz - 15 kHz.
Bernhard said:
Attachments
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.