Re: Coupling Caps
A capacitor /condenser diminishes reproduction because of losses inherent to construction and used materials. These negative properties are a function of the size and art of the plates, the dielectricum, chemicals and winding technique used.
Despite the good effort the writer gives a report for his loudspeakers only. Practice in speakerbuilding is to compensate one weakness with another. Not so for coupling amplifier stages, where the least loss is preferable.
In case one is ordering at Farnell, take a look at the Revox Rifa SMR series. In 63V there are 2.2 and 3.3uF metallised Polyphenylene Sulphide (PPS) caps with very low loss. These are not too expensive (3 - 4 euro) and what's the need for golden pins?.
Regards, Jaap
PS I used these for the HF filter but they measured quite diverse, so matching a few from a large stock was necessary. I don't think a 2-3% mismatch in the larger value will be of importance.
pantera6 said:
A capacitor /condenser diminishes reproduction because of losses inherent to construction and used materials. These negative properties are a function of the size and art of the plates, the dielectricum, chemicals and winding technique used.
Despite the good effort the writer gives a report for his loudspeakers only. Practice in speakerbuilding is to compensate one weakness with another. Not so for coupling amplifier stages, where the least loss is preferable.
In case one is ordering at Farnell, take a look at the Revox Rifa SMR series. In 63V there are 2.2 and 3.3uF metallised Polyphenylene Sulphide (PPS) caps with very low loss. These are not too expensive (3 - 4 euro) and what's the need for golden pins?.
Regards, Jaap
PS I used these for the HF filter but they measured quite diverse, so matching a few from a large stock was necessary. I don't think a 2-3% mismatch in the larger value will be of importance.
I have just tapped my discrete pcb onto my mates KI running opa2134 and compared sound here at work.
Considering the pcb was running on bodged up 12v regs and lots of flying leads and on a crap nad amp and mission / mordaunt short hybrid speakers here the sound was more open and the bass was tighter.
Vocals were much clearer indeed.
If i can hear that now then the gains at home are going to be much much more. Ill fit pcb when my Fets arrive.
PS Can I not stick with these 3.3uF caps. I have the feeling the 6uF are going to be too big.
Brent
Considering the pcb was running on bodged up 12v regs and lots of flying leads and on a crap nad amp and mission / mordaunt short hybrid speakers here the sound was more open and the bass was tighter.
Vocals were much clearer indeed.
If i can hear that now then the gains at home are going to be much much more. Ill fit pcb when my Fets arrive.
PS Can I not stick with these 3.3uF caps. I have the feeling the 6uF are going to be too big.
Brent
Hi guys,
I wanna know, before ask for it, the diffrence between AD8620AR, AD8620ARZ and AD8620BRZ ? Each time many letters...
I'll also order the stuff from Ray's list.
After I'll look for the choice of opamps, clock ( the Flea ? )...
For the OPA627BRG4 , they won't send it to me, delayed...
Update : no way to order from Farnell's, because they said I do not order enough of each... another way ?
Update II : I can order the caps that are numberous on the board... also, Ray what is +100n PPS ? Caps ? And ferrites are used in wich way ?? Thanks !!!
I wanna know, before ask for it, the diffrence between AD8620AR, AD8620ARZ and AD8620BRZ ? Each time many letters...
I'll also order the stuff from Ray's list.
After I'll look for the choice of opamps, clock ( the Flea ? )...
For the OPA627BRG4 , they won't send it to me, delayed...
Update : no way to order from Farnell's, because they said I do not order enough of each... another way ?
Update II : I can order the caps that are numberous on the board... also, Ray what is +100n PPS ? Caps ? And ferrites are used in wich way ?? Thanks !!!
Malefoda said:
Hi, the 'Z' at the end means the product is lead free. What the difference is between AD8620AR and AD8620BR can be read in the datasheet. In case you can't find it, it's located here
Jaap
PS Do you think it's wise to order these ICs? They are very small and it takes knowledge to solder these on the expensive Brown Dog sockets. Why don't you start modding the player and keep the opamps?
Farnell might not accept orders below 50 euro from private customers ...
Tonight i did the coax mod for Dac pin 4 to decoder.
RD14 was originally 220 in my cd67se, I lowered that one to 68 ohm. placed a 1n capacitor in series.
Also did the sat and slk (dac pin 11 and 12) to the cpu, didn't cut traces yet because I first wanted to listen to what it does. For these two coaxes I used a very thin silver coax wire.
Just listening now
RD14 was originally 220 in my cd67se, I lowered that one to 68 ohm. placed a 1n capacitor in series.
Also did the sat and slk (dac pin 11 and 12) to the cpu, didn't cut traces yet because I first wanted to listen to what it does. For these two coaxes I used a very thin silver coax wire.
Just listening now
Re: Re: Re: Re: Coupling Caps
This is good to know - Thanks! So before I go out and spend more on a pair of coupling caps than I bought the CD63
, I've got 2 questions for those of you in the know:
1. Can this FET/Transistor stage be DC Coupled?
2. (Maybe related to 1.) What would be the effect of taking out the high-pass filter (C5 & R12)?
Just trying to understand this circuit better (and learning about basic electronics at the same time)
Cheers,
Champi
disco said:
disco said:
This is good to know - Thanks! So before I go out and spend more on a pair of coupling caps than I bought the CD63
, I've got 2 questions for those of you in the know:1. Can this FET/Transistor stage be DC Coupled?
2. (Maybe related to 1.) What would be the effect of taking out the high-pass filter (C5 & R12)?
Just trying to understand this circuit better (and learning about basic electronics at the same time)
Cheers,
Champi
Re: Re: Re: Re: Re: Coupling Caps
You don't want to feed your amplifier with DC as it will destroy the loudspeakers (a.o.). The last capacitor leaves out the DC offset presented by the DAC. Another way to couple to your amplifier and get rid of the DC is by replacing the coupling cap by a transformer. Good ones are expensive though.
The HF-filter attenuates unwanted frequencies originating from the digital domain.
Jaap
pantera6 said:This is good to know - Thanks! So before I go out and spend more on a pair of coupling caps than I bought the CD63
1. Can this FET/Transistor stage be DC Coupled?
2. (Maybe related to 1.) What would be the effect of taking out the high-pass filter (C5 & R12)?
Just trying to understand this circuit better (and learning about basic electronics at the same time)
Cheers,
Champi
You don't want to feed your amplifier with DC as it will destroy the loudspeakers (a.o.). The last capacitor leaves out the DC offset presented by the DAC. Another way to couple to your amplifier and get rid of the DC is by replacing the coupling cap by a transformer. Good ones are expensive though.
The HF-filter attenuates unwanted frequencies originating from the digital domain.
Jaap
6h5c said:
Nice
3u3 is fine, as long as the input impedance of the following stage is not too low. 20kR will give you a ~2.4Hz/-3dB point with this cap. Shouldn't be a problem. I really have to replace the caps I use at the moment...
Ray.
Ray are you refering to R1 and R2 on your FET diagram. Change from 2.4K to 20K?
Brent