Thanks for the tip ! yes I do use icepower and like them a lot. maybe they can be improved ! very interesting !!! They would be surface mount i suppose ?
I know the class d preamp thing maybe is a stupid idee, but when I have a "perfect" power amplifier, why not "attck" the preamp.
But from Your answers I get the impression that there is not to much to gain here as the low level stages are already as good as can be. I settle for that for the time beeing.
I must check my ice modules to see if I can find the OP amps and identify them.
Thanks för all the answers !
Have a nice weekend all of You !
/
I know the class d preamp thing maybe is a stupid idee, but when I have a "perfect" power amplifier, why not "attck" the preamp.
But from Your answers I get the impression that there is not to much to gain here as the low level stages are already as good as can be. I settle for that for the time beeing.
I must check my ice modules to see if I can find the OP amps and identify them.
Thanks för all the answers !
Have a nice weekend all of You !
/
Jan-Peter said:
Stupid or not, first you have an analog signal, then you modulated it, filter it, then modualte it again and filter it again.TNT said:
You make PWM conversion twice and each time you degrade the original signal.
If you want some "digital" in your preamp you keep the signal digital all the way from the CD or DVD, manipuilate it in the digital domain then lastly convert it in the power amp.
You can never gain quality when you convert from analog to digital. Anybody why disagress with me?
TNT,
This is not true!
All selfoscillating Class-D amplifiers like, ICEpower, Mueta, Zappulse, UcD. Are an analog amplifier but working with modulating a PWM signal and demodulating. This has NOTHING to do with D/A or A/D conversion.
Regards,
Jan-Peter
www.hypex.nl
How did I miss this one first time around........?
Yep, pretty silly idea. Howcum all the Class D amps like Hypex and ICEpower use op-amps in the input stage? Gee, must be a reason. Wonder what it could be????? I believe that the guy in Denmark who makes ICEpower amps also makes a small preamp. (He even posts here sometimes.)
It has 2 op-amps inside.....................
Good luck trying to shove a dual op-amp into the board space for a quad...................
Jocko
Yep, pretty silly idea. Howcum all the Class D amps like Hypex and ICEpower use op-amps in the input stage? Gee, must be a reason. Wonder what it could be????? I believe that the guy in Denmark who makes ICEpower amps also makes a small preamp. (He even posts here sometimes.)
It has 2 op-amps inside.....................
Good luck trying to shove a dual op-amp into the board space for a quad...................
Jocko
Jocko,
I can only speak for the UcD.
The bare UcD amplifier stage has only a voltage gain of 4.5 times. When you preamp has an output of 5V rms, you don't need this extra gainstage......
Cheers,
Jan-Peter
www.hypex.nl
I can only speak for the UcD.
The bare UcD amplifier stage has only a voltage gain of 4.5 times. When you preamp has an output of 5V rms, you don't need this extra gainstage......
Cheers,
Jan-Peter
www.hypex.nl
Ok, OK - I admit it was not a good idee - please don't rub it in ;-)
For the record - I kniow there is no A/D or D/A going on in a class damp - that's what i tried to indicates saying "(and, it's NOT "digital")" !
however You agree, I hope, that some sort on conversion off the representation of the analog signal is going on ?
/
For the record - I kniow there is no A/D or D/A going on in a class damp - that's what i tried to indicates saying "(and, it's NOT "digital")" !
however You agree, I hope, that some sort on conversion off the representation of the analog signal is going on ?
/
Jan-Peter said:
Digital Pre-Amp
Well, with Class-D amplifiecatio already mis-named as digital in the forum name, I guess we could say that class-d or "digital" pre-amps are already on the market. They are called a DSP or digital signal processor. I have been working with the TAS3103 for quite a while and have another design with the AD21161 in the works.
However, it is quite possible to make a class D pre-amp as a class-D power amp like the ICE power or UcD180 are really just an op-amp that happens to have a really high output voltage swing and output current capacity.
On the other hand, the reasons for using class-d do not apply to a pre-amp. These are primarily high efficiency and low heat generation.
However, if someone wanted to do it for the sake of doing it, an analog PWM pre-amp is possible.
Well, with Class-D amplifiecatio already mis-named as digital in the forum name, I guess we could say that class-d or "digital" pre-amps are already on the market. They are called a DSP or digital signal processor. I have been working with the TAS3103 for quite a while and have another design with the AD21161 in the works.
However, it is quite possible to make a class D pre-amp as a class-D power amp like the ICE power or UcD180 are really just an op-amp that happens to have a really high output voltage swing and output current capacity.
On the other hand, the reasons for using class-d do not apply to a pre-amp. These are primarily high efficiency and low heat generation.
However, if someone wanted to do it for the sake of doing it, an analog PWM pre-amp is possible.
Hello all,
I am looking for a good diy pre-amp to connect to my still to built stereo UcD180 amplifier. I looked over the forum but couldn't find a hint. Worried about conventional pre-amps with no balanced output. As i understood it is adviceable to use a balanced pre-amp coz of the DC issue
Mathieu
I am looking for a good diy pre-amp to connect to my still to built stereo UcD180 amplifier. I looked over the forum but couldn't find a hint. Worried about conventional pre-amps with no balanced output. As i understood it is adviceable to use a balanced pre-amp coz of the DC issue
Mathieu
I made a 8 channel PWM logaritmic volume control last year. 0...-76 dB, controlled by -4,5...+4,5 V from linear potentiometer. It worked well for first try, but had a high distortion (1 %) at high attenuation. This was because of the switches (74HC4053), they have a high, very nonlinear capacitance. I managed to decrease this distortion to 0,05 %, but it needed very fast and expensive OPAs (AD8056). I didn't give up, I plan to use better switches and a cheaper and faster OPA, slightly different topology, but now I have other works to do.
This circuit have a 3rd order active filter on output, and 2nd order filter on input (more would have been better).
I like PWM very much!
Attached the first version before completion.
Operation principle
Improved sampler.
This circuit have a 3rd order active filter on output, and 2nd order filter on input (more would have been better).
I like PWM very much!
Attached the first version before completion.
Operation principle
Improved sampler.
Attachments
WOW, this old thread
I still believe it would be interesting. My ICE power still provide that stellar sonic surprises every day. Class D is a mode of operation and seem to do less harm to the original signal than other method of amplification -so why not in a high impedance situation?
Explore more, leave presumptions!!
/
I still believe it would be interesting. My ICE power still provide that stellar sonic surprises every day. Class D is a mode of operation and seem to do less harm to the original signal than other method of amplification -so why not in a high impedance situation?
Explore more, leave presumptions!!
/
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.