[sushimaster]

Hi everyone,

I just finished building a Clarinet. It seems to be working fine and sounding good right off the bat.

However, I do have one concern. In the manual it states the when you first power the preamp on, that the LED is suppose to be red, and then switch to green after 20 seconds. Mine seems to change from red to green after only 2 seconds when I turn the preamp on. Should I be concerned by this?

My initial suspicion is that maybe because I used .01 uF  250VAC ceramic radial capacitors for C100 & C101 instead of .01 uF 2kV as listed in the parts list. I had a hard time sourcing that exact part so I went with what I thought was the closest specs.

[TigerScent]

Hey I have a question too..., is it possible to construct/modify the Clarinet to have an output rating of <10 ohms, as the ME 550 Type I amp I have, requires this for optimal performance, having an unbalanced input of 1Kohms...

[sushimaster]

I think I found the answer to my question in another thread. That the differences in LED color change times is tube dependent.

The preamp is starting to sound wonderful as the components within are settling in. 

 

[poty]

..., is it possible to construct/modify the Clarinet to have an output rating of <10 ohms, as the ME 550 Type I amp I have, requires this for optimal performance, having an unbalanced input of 1Kohms...

It would be different preamp then. I think you are rather very anxious about this input-output resistance matching. First of all - you can just try to use unmodified version of the Clarinet and listen if something is wrong. Second consideration - sacrifice the preamp's gain to impedances matching - it can be achieved by using, for example, serial resistor on the preamp output (can be combined with volume control).
I'm not sure the amplifier is the best choice for tube gear anyway, but it is only my opinion.

[sushimaster]

Another issue I've run into which I could sure use some help with...I can't attach the bottom cover to the chassis.
Looking through the pictures of other built examples here, leads me to believe that there are suppose to be four metal clips that attach to the sides of the chassis where you put the screws into to hold the bottom cover to the chassis.

Now I don't know if mine never came with them or I just misplaced them.
Never the less, does anyone know what part number for these clips and where I may obtain them?
I don't see them listed in the build manual.
My best guess is that they are called mounting screw clips, with a threaded size 4/40?
Thanks in advance.

[TigerScent]

It would be different preamp then. I think you are rather very anxious about this input-output resistance matching. First of all - you can just try to use unmodified version of the Clarinet and listen if something is wrong. Second consideration - sacrifice the preamp's gain to impedances matching - it can be achieved by using, for example, serial resistor on the preamp output (can be combined with volume control).
I'm not sure the amplifier is the best choice for tube gear anyway, but it is only my opinion.

...I think it would be a super combination, if I can get the pre-amp output 'properly' to be under 10 ohms. 2 ohms would be ideal, that is what the ME pre-amp output is (SS), however, I want to use the Clarinet (modified) with the ME 550 Type I....if possible, as I am also building a Cornet2...

...so, a clear-concise hi-Q modification would be super...

Regards...

[TigerScent]

Another issue I've run into which I could sure use some help with...I can't attach the bottom cover to the chassis.
Looking through the pictures of other built examples here, leads me to believe that there are suppose to be four metal clips that attach to the sides of the chassis where you put the screws into to hold the bottom cover to the chassis.

Now I don't know if mine never came with them or I just misplaced them.
Never the less, does anyone know what part number for these clips and where I may obtain them?
I don't see them listed in the build manual.
My best guess is that they are called mounting screw clips, with a threaded size 4/40?
Thanks in advance.

...have you thought of making some up yourself??...it would not be difficult to do, I would imagine....

[TigerScent]

...sorry, didn't mean to hijack your thread...Ill start a new one, after I finish my Cornet2, on this subject...

[bregez]

In the manual it states the when you first power the preamp on, that the LED is suppose to be red, and then switch to green after 20 seconds. Mine seems to change from red to green after only 2 seconds when I turn the preamp on. Should I be concerned by this?

If the tube is indirectly heated (a new Sovtek) the LED will change in about 20 seconds.  If the tube is directly heated (an old RCA) then the LED will change in about 2 seconds.

[sushimaster]

Here it is. It's still early, but I think it's the best sounding preamp I have ever owned.
Even better than my slightly modded Conrad Johnson PV10 AL, which by the way is also 12AU7 based.

[poty]

...I think it would be a super combination, if I can get the pre-amp output 'properly' to be under 10 ohms. 2 ohms would be ideal, that is what the ME pre-amp output is (SS), however, I want to use the Clarinet (modified) with the ME 550 Type I....if possible, as I am also building a Cornet2... ...so, a clear-concise hi-Q modification would be super...

You are speaking about the mods which can't be done in the design. The only sensible solution may be interstage transformers. Solid state devices often needs more current than voltage to achieve nominal specs, often using electrolytic caps for interstage coupling because of that (you shouldn't be fooled by "DC coupled design" either).