Surprised by the result

[daschnoz]

I literally had all of the parts needed to build another mic. BM800 body, transistor and assorted other parts, capsule... so why not. I took the C12 topology and replaced the tube with a 2N5457. This is a transistor based clone of the tube mic that I made a month or so ago. The capsule here is the same one that I used in that tube mic. Same NTE10/3 x-fmr. So really the only difference is the active component (and the surrounding resistor values for bias and proper operation).

The tube version and the FET version have the same frequency response. I was expecting that the FET circuit would have a bit more top end than the tube, so this was a bit of a surprise.

What I really didn't expect... the FET version seems to have a bit more pop in the upper-mids... it responds faster - the guitar was there more quickly than the tube version, but at no greater amplitude than the tube.

Is this what people are talking about when they say that a tube mic has a more smooth or more mellow sound?

 

[rock soderstrom]

I literally had all of the parts needed to build another mic. BM800 body, transistor and assorted other parts, capsule... so why not. I took the C12 topology and replaced the tube with a 2N5457. This is a transistor based clone of the tube mic that I made a month or so ago. The capsule here is the same one that I used in that tube mic. Same NTE10/3 x-fmr. So really the only difference is the active component (and the surrounding resistor values for bias and proper operation).

That is very interesting, I have made similar attempts to replace tubes with JFETs. On this page something similar is done in a guitar amp environment.

Can you draw a small schematic sketch with your resistor values and adjustments please? I think each FET has to be biased individually, but I'm still interested in your values. Have you also tried other JFETS such as J201?

Is this what people are talking about when they say that a tube mic has a more smooth or more mellow sound?

My experience is that JFETs sound more direct and yes, also faster. I like the harmonic overtones/distortions of tubes better than those of JFETs, I think these are also responsible for the “larger than life” sound of good tube microphones.

Of course, this is all highly subjective so YMMV...

 

[mrgrooves666]

I literally had all of the parts needed to build another mic. BM800 body, transistor and assorted other parts, capsule... so why not. I took the C12 topology and replaced the tube with a 2N5457. This is a transistor based clone of the tube mic that I made a month or so ago. The capsule here is the same one that I used in that tube mic. Same NTE10/3 x-fmr. So really the only difference is the active component (and the surrounding resistor values for bias and proper operation).

The tube version and the FET version have the same frequency response. I was expecting that the FET circuit would have a bit more top end than the tube, so this was a bit of a surprise.

What I really didn't expect... the FET version seems to have a bit more pop in the upper-mids... it responds faster - the guitar was there more quickly than the tube version, but at no greater amplitude than the tube.

Is this what people are talking about when they say that a tube mic has a more smooth or more mellow sound?

Would you be kind to share the guitar tracks?
But, YMMV indeed... also similar with my own personal observations after rolling many of the tube and fet and opa mic projects available here, and trying them out....and why I stopped diy'ing tube mics. Different? yes, nice? yes, although not necessarily better.... worth the extra hassle of PSU, cable, and higher cost?....mmm not really... or at least not for me ..

 

[daschnoz]

It was a sand box project, so I deleted it. I can re-record something though. Ans yes, I'll be happy to share the schematic. But right now, I'm off to the annual Halloween parade through town. 1 kid is playing guitar on a float, the other kid is in the high school marching band.

 

[kingkorg]

Have you done the test with exact same source material, recorded in the same exact way, same exact conditions? When i did this kind of test, under normal operating conditions with no clipping, linear operating region, i couldn't hear any difference and the tracks canceled in the null test. Even the pink noise track. I did this multiple times, with multiple circuits and capsules as i have modular circuit/capsule system.

Even humidity and temperature on day to day basis can make capsules sound slightly different. Which might sway the result. This could be just one of many reasons why you got the impression you describe.

Imho, tubes vs fets start sounding different when pushed. Gross oversimplification as there are tons of different topologies for each, so even this might not be the case.