stereo preamp project

[accmeint]

Hello,

I am building the "stereo preamp" that Doug has in the library.  I have a question about the schematic at this link:

http://www.el34world.com/projects/images/stereopreampschematic.gif

My question is about how the bass pot is wired and if I am interpreting the schematic correctly.  Is that a 4 way connection involving one leg of the bass and treble pots, the bass pot wiper,  and the .022 capacitor?

The schematic appears to show all 3 legs of the bass pot connected, However when I look at the following link:

http://www.el34world.com/projects/images/DSCN1864.JPG

It shows only 2 of the bass pot termainals connected,   and the middle connector (wiper) of the bass pot connected to the treble pot.


Thank you

[eleventeen]

Hmmm. Good question. While you're at it, I see no connection to the wipers of the middle controls in the photo! OR, the output level pots!

Must be a "work in progress" pix, no?

[sluckey]

Is that a 4 way connection involving one leg of the bass and treble pots, the bass pot wiper,  and the .022 capacitor?

Yes

The bass pot is wired as a variable resistor, so only two terminal connections are necessary. However, many people prefer to connect the wiper to one end of the pot (it still functions as a 2 terminal variable resistor). The reason is that in the event that the wiper should break or lose contact with the carbon track resistor, the pot will go to maximum value rather than become an open circuit. I wire my variable resistors like this for that reason.

[accmeint]

Thank you for the info!   While Im here let me ask another question...Would it be possible to feed the output of one preamp into the input of the second preamp?   Would there be an impedance issue?


Thank you

[sluckey]

No impedance problem. Probably have a high gain squeal issue though.

[accmeint]

Hello,

I am building the "stereo preamp" that Doug has in the library.  I have a question about the schematic at this link:

http://www.el34world.com/projects/images/stereopreampschematic.gif

Where does the wiper of the "Output" pot connect on the schematic?

Thank you!

[LooseChange]

To the output jack.

[osupoke]

Sorry to dig up such an old topic, but there is no other discussions on this topic. I would like to build this project and would like to know if there is a BOM? I have looked through the link for the build and can't seem to find one. https://el34world.com/projects/StereoPreAmp1.htm
Can this be adjusted for home listening use, or is this more of a guitar application?
Thanks

[PRR]

> Can this be adjusted for home listening use, or is this more of a guitar application?

Totally guitar. Less or more or MORE distortion, heavy tone-tampering. Does not belong in a Hi-Fidelity system.

[osupoke]

Ok, is there a way to modify this for a home hifi use? Or does anyone have a design for one?

[shooter]

keep scrolling down this page n you'll find "handy links", schematics, Audio/PA

I like this "template";

https://el34world.com/charts/Schematics/files/Audio_pa/Marantz_hifi_2x6ca7.pdf
I'm tinkering now, 12AU7 or6SN7 with 2 or 4 EL84's configed  PSE, or a KT120, or 88, or........

[1blueheron]

Ok, is there a way to modify this for a home hifi use? Or does anyone have a design for one?

Can you qualify "home hi-fi" use a little bit?  What are your expectations?  What equipment will this be connected to: turntable/cartridge, tube amp, hi-end esoteric speakers or a mp3 into preamp for ear bud listening through a tube preamp?  Lot of territory to cover.

Is this a cornerstone around which you will begin to build an entire system or will it be placed into an existing setup?  There are tons of tube preamp designs out there.  Picking one depends a lot on application and expectations.  How many input do you need and at what level?  Is this a minimalist approach with just a volume knob, or do you want a lot of bells and whistles and multiple input selections, equalizations, etc.?

[osupoke]

I wanted to build this as the center of the system with a minimalist approach. Just one or two inputs with bass and treble control. I do not have a power amp selected as of yet, but have plans on building it around the pre. So, I would like to preamp to be kinda universal with most power amp designs, almost generically speaking. Just using this to play digital media, no phono.
So, my expectations are that I just want something on the simpler side of the hifi world that still sounds "good". I know "good" doesn't tell you much, but I'm not picky really.
I hope that helps.

[1blueheron]

I wanted to build this as the center of the system with a minimalist approach. Just one or two inputs with bass and treble control. I do not have a power amp selected as of yet, but have plans on building it around the pre. So, I would like to preamp to be kinda universal with most power amp designs, almost generically speaking. Just using this to play digital media, no phono.
So, my expectations are that I just want something on the simpler side of the hifi world that still sounds "good". I know "good" doesn't tell you much, but I'm not picky really.
I hope that helps.

"Hi-Fi" typically seeks to produce a nearly flat frequency response from 20Hz to 20kHz.  The electronics should be as "transparent" to the listener as possible without adding "color" or a sonic signature of its own.  Tubes tend to be a little more colorful.  That said, there are many well respected tube pre-amp designs and tubes do a wonderful job when it comes to articulating musical detail.  Here is a starting point you might want to consider.  Simple and minimalist. Pretty flat response curve.  Lots of build options.   PCB or PTP.  SS or tube Power supply. Uses currently available tubes.

http://diyaudioprojects.com/Tubes/12AX7_Preamp/