please give some comment for this preamp sch

[ashok]

seems to me that there are still a few ignorants around hoping to outdo Saul Marantz?

This is a DIY forum. Practically everyone who makes and designs circuits use ideas from older designs and try to generate some of their own. This configuration is so basic that it most likely predates S.Marantz by quite a bit. Does that make S.Marantz also 'ignorant'?

Does this make all DIY guys 'ignorant' ?
Please make comments responsibly. We all need to be far above this way of thinking.
Cheers.

[KaLok]

The schematic is a China kit, it is a Mcintosh c22.

[fdegrove]

Hi,

This configuration is so basic that it most likely predates S.Marantz by quite a bit. Does that make S.Marantz also 'ignorant'?

It is indeed a very basic circuit but it's still a very popular preamp many people try to copy hoping to "clone" the famous sound of the 7C.

To the best of my knowledge not a single one has ever succeded, especially if you add the phono stage to the equation.
Heck, not even Marantz ( the actual company) came close when they reissued the preamp several years ago.

That is why I warned against this.

No offense to you at all Ashok.

Cheers,

[ashok]

Hi Frank,
It is indeed difficult to clone a circuit or system to sound like another one that looks identical on paper. There are too many variables involved that interact with each other. It will be very difficult if not impossible to make it identical in every single way.

I think Takashi was just trying to make a good preamp with no intentions of 'cloning' any particular design. In fact he was not trying to add a phono stage either. I think the discussions we had in this thread were interesting and resulted in us looking at some variation. Takashi might just make the modified circuit . I think many of us would like to know how it sounds. It will satisfy his need for a good pre amp and ours for experimenting.
We are all having fun and learning at the same time.
Cheers.

[ashok]

Hi Takashi,
Here are the results I got while simulating the circuits. The second one is for the circuit seen on the zip file I posted last. This has feedback from the output of the CF stage and C5 = 22uF
( not 2.2uF ).

Old circuit ( you posted)
Distortion at 2Volts rms into 10 k ohms
At 1kHz 0.03% 2nd harmonic and 0.0023% 3rd harmonic.
Response is -0.5db at 20Hz and -0.3db at 20Khz.
-4.4db at 100kHz , -1.7db at 10Hz , and +13.3db at 2 Hz(bad)
Max output voltage into 10Kohms is 20.7 volts rms
Voltage gain is 20db ( x 10).
Dc current drawn by the circuit at 250 volts supply is 7mA total.

New modified circuit ( C5=22uF)
Dist. at 2 V rms into 10 K ohms
At 1Khz 0.0045% 2nd harmonic , and 0.00017% 3rd harmonic.
Response is 0db from 2Hz to 10Khz , -2.7db at 20Khz and -4.1db at 100Khz. At 2Hz the response is +0.68db ( OK).
Maximum output voltage into 10K ohms is 27.6 volts rms.
Voltage gain is 21db ( x 11.2).
Dc current of the ckt is 8.8 mA at 250 V dc.

Note that I used two 15pF capacitors at the input to simulate stray capacitances as shown in the last circuit diagram.
I don't know if this circuit is stable at HF.
Cheers.

[takashi]

dear all
yes, i will not add the phono parts since it is not useful for me.
i built this pre-amp last year, and i think its time to have some mod on it. yes, i bought this kit in china, but it dosnt means i cannot mod it. but i am new and havnt too much experiences in tube, so i beg for the help from this forum.
and after discuess with all you guys, i know more about tube and how to mod the tube.

so , all i asked because i dont know, all i did is because i want to do! since it is my interest.

next time i will do a tube power amp project!

and i need to say thanks to those guys who help me!
thanks a lot.

[takashi]

and also, i am not cloning any amp...
i am not able to design a tube amp by myself, so i use money to buy kit. and i want to know it more, and mod it, so that i can have my own tube pre-amp.

special thanks to ashok

[Joel]

Is this going to be used for headphones at all?