I promissed you a better mousetrap then the ECHO Etreme and here it comes. It is a modification of the Rositter Headamp so i call it ROSI.
I had 5 goals : ease of build, very affordable, no exotic components and good measurements and sound. I think i have succeded. The circuit has a lot of advantages and view disadvantages.
Advantages are: simplicity, very low noise, no hum, no current through the cartridge, DC coupled input, no DC at the output, high speed (-3dB is over 5MHz), very low distortion (it is theoretically 100 times less then the Hiraga with an equal spread of 2nd and 3rd harmonic and nothing else.
Disadvantages: Elkap for AC decoupling, coupling caps to the output.
The circuit works in the folowing way: i use 2 rows of 2N4401/2N4403 at the input as common base stage. Rbb on this transistors is 40 Ohms and i use 1mA of bias on each for a total of 8mA. I reduced basing resistors to the minimum for less noise so the theoretical noise resistance is 40 / 8 = 5 + 5 / 2 = 7.5 Ohm. In praxis the circuit it dead quiet. No hum and no audible hiss at the listening seat at absurd volume with my 0.5mV Titan. T9 and T10 are BC517/516 darlingtons. They form a lokal high current feedback loop and couple the signal to the output. I used Pannasonnic FC Elcaps for decoupling and Rifa PHE450 caps at the output. The circuit runs on a single floating supply so ground planes have to be seperated between the channels. I build the circuit in 5 hours and it worked fine immediately. Listening to it with the Active Inductive RIAA i found the sound a bit brash at first and at super high volume there was a faint frensh radio station. I solved that with 10nF to ground at the input and 12.2 nF to ground at the output. The sound is now very dynamic and transparent. I like it a lot. Highly recomended when you are on a tight budjed and have a low impedance MC. Gain is very high and can be lowered by lowering the 680 Ohm and or the 340 Ohm resistors. I build the circuit on a double copper clad PCB without case. I cut the top groundplane in half with a cutter knife.
I had 5 goals : ease of build, very affordable, no exotic components and good measurements and sound. I think i have succeded. The circuit has a lot of advantages and view disadvantages.
Advantages are: simplicity, very low noise, no hum, no current through the cartridge, DC coupled input, no DC at the output, high speed (-3dB is over 5MHz), very low distortion (it is theoretically 100 times less then the Hiraga with an equal spread of 2nd and 3rd harmonic and nothing else.
Disadvantages: Elkap for AC decoupling, coupling caps to the output.
The circuit works in the folowing way: i use 2 rows of 2N4401/2N4403 at the input as common base stage. Rbb on this transistors is 40 Ohms and i use 1mA of bias on each for a total of 8mA. I reduced basing resistors to the minimum for less noise so the theoretical noise resistance is 40 / 8 = 5 + 5 / 2 = 7.5 Ohm. In praxis the circuit it dead quiet. No hum and no audible hiss at the listening seat at absurd volume with my 0.5mV Titan. T9 and T10 are BC517/516 darlingtons. They form a lokal high current feedback loop and couple the signal to the output. I used Pannasonnic FC Elcaps for decoupling and Rifa PHE450 caps at the output. The circuit runs on a single floating supply so ground planes have to be seperated between the channels. I build the circuit in 5 hours and it worked fine immediately. Listening to it with the Active Inductive RIAA i found the sound a bit brash at first and at super high volume there was a faint frensh radio station. I solved that with 10nF to ground at the input and 12.2 nF to ground at the output. The sound is now very dynamic and transparent. I like it a lot. Highly recomended when you are on a tight budjed and have a low impedance MC. Gain is very high and can be lowered by lowering the 680 Ohm and or the 340 Ohm resistors. I build the circuit on a double copper clad PCB without case. I cut the top groundplane in half with a cutter knife.
Joachim,
Sorry, I got thge Post # wrong. It's the MPP low Z headamp schema from Post # 731.
At the output you have paralled C5 (10nF) and R8 (220R) and lable them as 2.2uS transimpedance.
This was what I was questioning. I see no problems with your basic RIAA numbers in the opamp section.
Why this rolloff at the output of the headamp? As I said, if was intended as the "Neumann" tweak then it shouldn't be a roll off, but a response flattening.
Regards, Allen
Sorry, I got thge Post # wrong. It's the MPP low Z headamp schema from Post # 731.
At the output you have paralled C5 (10nF) and R8 (220R) and lable them as 2.2uS transimpedance.
This was what I was questioning. I see no problems with your basic RIAA numbers in the opamp section.
Why this rolloff at the output of the headamp? As I said, if was intended as the "Neumann" tweak then it shouldn't be a roll off, but a response flattening.
Regards, Allen
Allen !
I think i explained that. The 100kOhm resistor in the servo makes the response a little rise over 20kHz and the output stage can only have a gain of 1 ultimatey so does a liitle mistake up there too. The 2.2usec compensates for that for a cassic Litschitz RIAA result. You can leave the cap out and then you are not far from what you do. You could lower the 100kOhm servo resistor for even more gain over 20kHz if that is the goal.
I think i explained that. The 100kOhm resistor in the servo makes the response a little rise over 20kHz and the output stage can only have a gain of 1 ultimatey so does a liitle mistake up there too. The 2.2usec compensates for that for a cassic Litschitz RIAA result. You can leave the cap out and then you are not far from what you do. You could lower the 100kOhm servo resistor for even more gain over 20kHz if that is the goal.
I work with intuition and experience. That way i can enhance the creative process. First i DO something and then i Think about it. It´s a work in progress anyway. I am very tolerant to mistakes, also to ones that others make. It´s about the music i feel and not about proving anything so strict scientific anylisis is much better done by the mathematicians. If they know how to produce good sound is another question.
Hey mate. Well for starters, a pun is a play on words. So for example, I will quote this phrase to you: "the pun is mightier than the sword!" However we all know that the proper phrase is "the PEN is mightier than the sword." Therefore, the first phrase I quoted was a pun - a play on the word "pen."
Now what happens sometimes, and you will find this often in articles that are intended to be humorous, is that the phrase will be quoted with the added remark, "no pun intended"
eg: The pun is mightier than the sword. (no pun intended!)
It's really just a light-hearted way for the writer to acknowledge the fact that they have made a pun, but wasn't necessarily intended to come out that way. In some cases the pun really *was* intended, but like I said it's just a funny way of bringing it to the notice of the reader.
As far as choosing a best answer, you have the ability to pick one within three days of asking the question - it's fairly straightforward, there should be an option under each of your answers to pick it as the best. Anything after three days, and the question goes to a vote, which means the whole Yahoo Answers community get to pick a best answer.
Hope that helps!
And just remember - you can tune a guitar, but you can't tuna fish! (no pun intended...)
Hey mate. Well for starters, a pun is a play on words. So for example, I will quote this phrase to you: "the pun is mightier than the sword!" However we all know that the proper phrase is "the PEN is mightier than the sword." Therefore, the first phrase I quoted was a pun - a play on the word "pen."
Now what happens sometimes, and you will find this often in articles that are intended to be humorous, is that the phrase will be quoted with the added remark, "no pun intended"
eg: The pun is mightier than the sword. (no pun intended!)
It's really just a light-hearted way for the writer to acknowledge the fact that they have made a pun, but wasn't necessarily intended to come out that way. In some cases the pun really *was* intended, but like I said it's just a funny way of bringing it to the notice of the reader.
As far as choosing a best answer, you have the ability to pick one within three days of asking the question - it's fairly straightforward, there should be an option under each of your answers to pick it as the best. Anything after three days, and the question goes to a vote, which means the whole Yahoo Answers community get to pick a best answer.
Hope that helps!
And just remember - you can tune a guitar, but you can't tuna fish! (no pun intended...)