[JayB]

I finally started assembling my Clarinet. I decided to use an enclosure I had purchased from Parmetal for a project that was never done. It will allow me to surround everything including the tubes in metal coated with an anti RFI/EMI treatment. All components, including the tubes, will be mounted on the same side of the board. The signal caps will me mounted along side the circuit board on terminal strips. The transformer will be positioned to the right of the partition. This thing is big and a little flimsy so I may have to do a little damping, especially on the top and bottom plates. Parts selection includes Vishay, Mundorf, Kiwame, FT-3 teflons, to name a few.






Before I proceed further, I do have a few questions:

1.   I have used Vishay nudes in signal path positions. Not sure whether r304 and r314 would be appropriate for them given their low wattage.

2.   In position c301, which end is the input? Its not clear to me from the circuit board.

3.   Where do I attach the black meter lead when doing the two voltage checks?

Thanks to all who have posted their Clarinet experiences. This project would not be possible for me without your help. I will post more pictures when I'm finished, as well as discuss its sound.

[PatOMalley]

The tubes need to mount from the opposite side of the board.

[hotrod]

 It's hard not having it in front of me to know for sure,but I think you are correct.The soldering tabs on the sockets will not be in the proper holes in the board?Like I said its hard to tell if it will just be 180' off or 180' and backwards,everything is a little fuzzy today.
 I would definitly flip the board over and mount everything like it should(fab some long standoffs for attatching to bottom plate if not wanting tubes exposed),there is really no benifit mounting it the way you have it now,but of coarse, just an opinion.

[hagtech]

1) These resistors are filtering in the power supply, do not need anything special.  No audio signal through them.

2) This is also in power supply.  The high side is tied to the "+" on C300.

3) DC voltages are measured wrt ground.

4) You have to flip the sockets to other side.

jh

[david62]

Nice except for the tube socket problem.

[poty]

To eliminate a lot of resoldering you can flip only "big" parts to the other side (there are not so many of it - electrolythic capacitors, tubes, transistors...).
It's possible of course to use some kind of "convertors" for the purpose of not resoldering at all. The 5Y3 socket you can just rotate one pin.

[tubesforever]

Cut off the sockets.  Then desolder just the leads and use no clean wick or a desoldering suction tool to clean the traces.   This way you don't need to worry about lifting the traces or cracking the pcb. 

It a lot easier than you think once you cut off and ditch the sockets and solder new ones from the top.

You can get those cool vinyl stand offs in different heights to get the tubes up where you need them.  make sure you leave enough room to make tube rolls easy.  If you have only one option to remove the top or bottom, put the valves where they are easiest to roll.

This phono section deserves easy tube rolls. 

You are going to love the nude Vishays and Teflons.  They make my Cornet 2 sound like a much more expensive phono section.

Kudo's on your project.  The box is super big like my 250 watt per channel class A amplifier.  Dang you gotta love this kind of room.   Its going to sound superb!

Cheers! 

 

[JayB]

Holy cow! I never thought about the sockets being flipped 180. Thanks. If I put the tubes, caps, and heat sinks on the same side of the the board facing up, then I can get the assembly under the hood. Assuming that the heat sinks can be reversed?

[david62]

Keep us posted on your progress.

[harryf]

If you have a sloder sucking pen you can pull out the socket's.if youARE PATIENT.I put 4 out of five on the wrong side of my cymbal's.What i did was heat and suck all the pin's.Then when none was left but the solder that attached's the pin to the board i wiggle the pin with a flat head screwdriver.then i pull the iron off while wiggleing the pin.It will stay lose if you sucked 95% of the solder out.Them wiggle the whole part.There will be one that still sticks.Heat it up and pull the whole thing out.
Be super patient.Don't pull hard!!!
Build it like stock.Even if you have to drill out the top.
It will not hum no need for sheilding.
Good luck!

[poty]

I insist that the easist way off the mistake - is to use some kind of socket convertors.

[JayB]

I decided to go ahead and remove the heatsinks, tube sockets and electro caps and mounted them on the other side. I used a desoldering braid. Visual inspection of the board showed no cracks, etc. I hate rework, but it was obviously necessary in the case of the sockets.

Does anyone know where to get heat shrink larger than an inch in diameter? I want to cover the FT3's, which are about 1 1/8" in diameter.

[david62]

Good job de-solderimng and remounting.You are on your way to a great sounding preamp.Tubesforever probably knows where you can get the large size heat shrink that you need for the FT3's.
Dave

[Bill Epstein]

Try Mouser for 1 1/4" heatshrink.

[JayB]

I have been a bit more deliberate since the tube sockets mistake, but am about 90% complete. The chassis work has been a pain, but does look pretty good. I'll post picture as soon as I get a new cable for my camera.

So, the final 10%:   

1.   I’m trying to figure out how to hook up a couple of Dale ladder mono pots. Each one has three wires (input/output,ground) coming out of it. I don't know which is which. The measured resistance between wires is as follows: Green/Brown 0, Green/Blue 50k, Blue/Brown 50k. The green wire is attached to one of the resistors, and the brown and blue wires are attached to lugs coming out of the plastic body. I can make a pretty good guess, but I would like to here from someone who has used them.   

2.   On average, my wall outlets give me about 125 vac (peaks as high as 129). Setting the power supply to run at 120 vac, will this be a problem in terms sound or parts longevity? I do have a variac I could bring in, though don't like it because its buzzes (ambient).

3.   I used metal screws to attach the circuit board to the chassis. Is this going to create a ground problem?

4.   Which of the 10 output wires from the transformer would it be prudent to twist on their way to the circuit board? 

5.   I mounted the LED on the front panel, so I will have to run some wires from the circuit board connection. Should I worry about these wires creating any hum? The instructions mention "tab on side labeled "LED*". What TAB? Is the led "directional"?

I'm really looking forward to getting this thing turned on.

Thanks.


 

[poty]

1. I’m trying to figure out how to hook up a couple of Dale ladder mono pots.

Can't understand what you realy mean... Sorry...

2. ...my wall outlets give me about 125 vac ... Setting the power supply to run at 120 vac, will this be a problem in terms sound or parts longevity?

I think no problem here. The most sensitive part is heating, but the device has 6,2V in heating (6,3V rated), so it's no problem.

3. I used metal screws to attach the circuit board to the chassis. Is this going to create a ground problem?

It may depends. But generally I don't think it is SO important.

4.   Which of the 10 output wires from the transformer would it be prudent to twist on their way to the circuit board? 

Primary winding wires - one cable, secondary high - second cable, 5V - third, 6.3V -fourth.

5.   I mounted the LED on the front panel, so I will have to run some wires from the circuit board connection. Should I worry about these wires creating any hum?

It may be possible (hum), but you always can twist the wires and change their position in the box to minimize this.

Is the led "directional"?

Yes,it is.

[JayB]

A few pictures.





I decided not to use the standoffs and attached the circuit board, transformer, etc. to aluminum extrusions bolted to all sides of the chassis. The result is a very stiff assembly which allows for very easy access to everything. 

When I first turned it on, nothing. Installing the fuse helps. Voltages checked out and its playing music. Considering all of the re-soldering I did, I was very apprehensive, but everything seems fine. I won’t comment too much on the sound until its broken in except to say that the sound stage is huge and everything is more relaxed than with my passive setup. I’m using some cheap Sylvania tubes during break in, to be replaced by some Jan type Mullards after everything settles in. I used some very high-quality parts in this build so I don’t foresee rolling anything but tubes.

Overall, I think this kit is superb. It was harder than building my Bottlehead stuff and was probably at the top limit of my skills. The circuit board is a thing of beauty (worthy of framing) and is definitely preferable to point-to-point wiring.

[Bill Epstein]

I'm delighted you carried your vision to reality and it sounds so good.

[GRD]

Stellar!  Thanks for posting.

[david62]

Sweet! I can see that you followed the advice of those here in the know and tweeked your Clarinet about to the max.I hope that you can sit back and enjoy the fruits of your labor.What other components are you using the Clarinet with?
Dave