tube circuit conversions?

[basshoven]

Okay I am a new member here so this is my first post. I am reaching out here since I am also a newbie at this tube electronics. Building and following schematics are fairly easy for me, but trying to understand weather a specific type of tube will work in a circuit is a lost concept to me right now...LOL
Anyways I had a few 6SN7EH's lying around and decided to build an overdrive with it...I followed an old schematic called the "westbury tube-w-20"
and added a linestage tone control...all fairly simple to build but it calls for 12AX7's....I simply rearranged the circuitry to work with the pinouts of the octal based tubes, upped the voltage, and built this.
It's all nicely laid out and it don't work.....in fact it buzzes like a SOB.
So.....aside from using different tubes, how much of a circuit design change do I need to make in order for these tubes to work?
Seems I just pulled a novice build here by NOT testing before I put it together....

[aardvarkash10]

Schematic please?

[Miniwatt]

If you just changed the tube you would have more than just a buzz. I'd say you did something else wrong.

[basshoven]

[IMG]file:///C:/Users/SHANNO%7E1/AppData/Local/Temp/moz-screenshot-2.png[/IMG][IMG]file:///C:/Users/SHANNO%7E1/AppData/Local/Temp/moz-screenshot-3.png[/IMG]i am going to try to upload the schematics of both the circuits....I rechecked all my wiring...I used a buss as a common ground instead of the chassis, I was'nt too sure what would happen if I connected to the chassis, would my other system's ground which has a live voltage going through it....as is all the household components seem to be. the green ground wire is connected to the neutral white wire in just about every breaker box i see in a house..kinda makes me nervous..lol
the box i build sounds exactly as if you put your finger on the end of a guitar cable input plug to the amp, that kind of buzzing.

[basshoven]

[basshoven]

[IMG]file:///C:/Users/shannonchase/Pictures/Amp-Tone-2-A-A.gif[/IMG]

well i posted them both, hopefully they showed up. these are the circuits i used...

[rman]

Hi. just making sure you know that tube pin out diagrams are looking at the socket from the bottom.

Cheers.

[DF96]

Almost certainly a grounding problem. Do some reading on star and bus grounds, and how to connect to safety ground.

The 6SN7 is nothing like a 12AX7. It has lower gain, and generally runs at a higher current. As a first guess I would try reducing the anode and cathode resistors by a factor of 2 or 3. Don't worry about exact operating point, as this is an effects box not hi-fi.

This looks to be a peculiar circuit (I am not a guitarist!). First it throws away all the higher frequencies (so all guitars will sound the same?). Then it re-introduces higher frequencies as pure distortion from clipping diodes in what at first sight looks like a feedback loop, but with a cathode bypass so it isn't really a feedback loop.

[mastodon]

[IMG]file:///C:/Users/nnnn/Pictures/Amp-Tone-2-A-A.gif[/IMG]

You need to upload the file to the internet somewhere before you can include it in a post. Kinda blows your cover, this.

Please post a schematic of what you actually built. Also try to trace if you made any mistakes wiring the circuit (put the schematic aside for a moment and try to draw it based on the circuit you built).

This looks to be a peculiar circuit (I am not a guitarist!). First it throws away all the higher frequencies (so all guitars will sound the same?). Then it re-introduces higher frequencies as pure distortion from clipping diodes in what at first sight looks like a feedback loop, but with a cathode bypass so it isn't really a feedback loop.

The quasi-feedback is a tad odd, but the filtering and use of double diodes is very common in fuzzboxes, and indeed the most-used method of obtaining a rich and heavy metal type distortion. I suppose feeding back the clipped signal should 'warm up' the diode-altered spectrum.

[basshoven]

Ok thank you guys so much for your input so far...Yes this is an effect based box, an overdriver used for my bass guitar to be used inline with the effects in/out jacks in the back of the SWR amp. I was told there particular 6SN7 tubes are the best for this, just had to find a circuit for it. This was obviously my first try. I will have the circuit drawn as I have built it and post it up soon...my biggest obstacle was connecting the 2 circuits together and that's where I think the problem lies...