[BUILD] GIX-51X tube preamp

[Toure14]

what about the LS for some of the WIMA caps is that just for pricing options as well? what is the size that was originally spec'd? so it is safe to assume all CAPS are electrolytic if not stated as something else?

 

[gemini86]

what about the LS for some of the WIMA caps is that just for pricing options as well? what is the size that was originally spec'd? so it is safe to assume all CAPS are electrolytic if not stated as something else?

The options listed are just options. Some are more available than others so I added pads for multiple LS options. I generally go by price there as well.

Anything that's not marked as a film cap is an electrolytic. The lead spacing for them should be 5mm, but anything close will work. Unless you use snap-ins, the leads will be plenty long enough to fit whatever lead spacing needed.

 

[Toure14]

Almost done with the Mouser cart few more questions:

on these caps there is no specified voltage so is 35V okay to use?
  100u   3 "C26, C27, C29"
  470u   1 "C11"
  47u   1 "C28"

on this cap the specified LS isn't an option. Only 15mm. Can I use another 15mm instead which is the exact same as "C3"?
  470n   1 "C5" 5/7.5/10mm LS WIMA 250V

These part numbers aren't readily available (backordered). Are there any subs?
  ES3G   1 "D501" (mouser)625-ES3G-E3
  330uH   1 "L501" (mouser)652-SRR1210-331M

 

[jandoste]

Hey Rodney,
I allready solder L503 but maybe i must change it no?
thanks

 

[gemini86]

Almost done with the Mouser cart few more questions:

on these caps there is no specified voltage so is 35V okay to use?
  100u   3 "C26, C27, C29"
  470u   1 "C11"
  47u   1 "C28"

on this cap the specified LS isn't an option. Only 15mm. Can I use another 15mm instead which is the exact same as "C3"?
  470n   1 "C5" 5/7.5/10mm LS WIMA 250V

These part numbers aren't readily available (backordered). Are there any subs?
  ES3G   1 "D501" (mouser)625-ES3G-E3
  330uH   1 "L501" (mouser)652-SRR1210-331M

100u   3 "C26, C27, C29" should all be 35V

  47u   1 "C28" should be 63V

  470u   1 "C11" is for V2's cathode, which is very low voltage so it can be as low as 6.3V.

This inductor for L501 may fit... it's slightly larger, (by .5mm) so you'll have to try your luck, or keep sifting through the mouser catalog for something closer. Or digikey has them in stock.

This diode for D501 will work perfectly. It's the same diode but with a 300V reverse breakdown instead of 400V, which is still a safe margin above the 250V output of the converter.

 

[gemini86]

Hey Rodney,
I allready solder L503 but maybe i must change it no?
thanks

Yeah the originally spec'd L503 is not correct. Change it out for a 1.2mH part (part # in BOM)

 

[jandoste]

Thanks Rodney!

 

[Toure14]

Last question and my cart should be completed today and Rodney and I can send it to you for review.

"C5" and "C3" have the same capacitance rating the only difference being the Lead Spacing requirements. I read on page 2 of the thread that the leads had to be bent for "C3" at 15mm LS and currently when I search WIMA caps as according to the BOM for "C3" and "C5" at the given values .47u and 250V, only 15mm LS is available.

When I drop the voltage to 100V I get 5/7.5/10 mm LS options which would probably work much better for the CAPS spacing requirements, however the voltage drop is significant.

My question is can I use 100 volt WIMA CAPS for "C3" and "C5" instead of 250V?

 

[gemini86]

The difference between c3 and c5 is that c3 must be 250V, where c5 can be 100V, since it is only block the DC from v1A's cathode when at low gain settings, which will be around 80V max. I'll change the bom to reflect that.

RE: c3 touching the tube pins... thepins will get warm as the tube heats up. But it's my experience that these low power tubes only get warm, not HOT. I can pull a hot tube out bare handed without discomfort. The cap's plastic housing will be rated for much higher operating temperatures. It's not exactly pretty, but it's fine.

 

[Toure14]

The difference between c3 and c5 is that c3 must be 250V, where c5 can be 100V, since it is only block the DC from v1A's cathode when at low gain settings, which will be around 80V max. I'll change the bom to reflect that.

RE: c3 touching the tube pins... thepins will get warm as the tube heats up. But it's my experience that these low power tubes only get warm, not HOT. I can pull a hot tube out bare handed without discomfort. The cap's plastic housing will be rated for much higher operating temperatures. It's not exactly pretty, but it's fine.

Thanks Rodney...I'm going to go over my cart and then share it with you and then hopefully before the day is out this build can have an official Mouser cart minus the 50k Log which is from mammoth audio.

 

[Toure14]

Okay this is just out of pure curiosity Rodney, but would 100v work for c7 instead of 63v keeping the same capacitance?

 

[gemini86]

Higher voltage rating is always ok. If it fits, it's good.

 

[Toure14]

Higher voltage rating is always ok. If it fits, it's good.

Okay thanks. I sent you an email with a link to the mouser cart I put together. If you verify everything then you can post it to the beginning of this thread for everyone to use. I followed the order of the BOM so a person can literally go right down the line item by item.

Only thing missing is the 50'k log from mammoth but i'm sure you can post a link for that right under the cart if you approve it.

I don't know how to measure the knobs or which ones to recommend to folks so i guess you can post that info in the BOM as well.

Thanks for the assistance
G

 

[gemini86]

Looks pretty good to me. Thanks for doing that, Toure. Updated first post with the mouser cart.

 

[Winetree]

Looked at first post.
Where's the Mouser Cart?

 

[Toure14]

Looked at first post.
Where's the Mouser Cart?

I don't know how to do the whole hyper link thing where I can attach it to the words "Mouser Cart"

 

[gemini86]

Ummm. Sorry, it was there last night but I'm not seeing my changes. I'll try again at lunch. Maybe the edit didn't go through.

 

[gemini86]

there.. fixed it.

 

[maq3396]

Thanks for this build everyone!

Looking forward to building a pair of these.

Mine will be for male and female vocals.

Can anyone comment on tube selection or optimal input/output transformer for this application?

Thanks in advance

Cheers
Mac

 

[gemini86]

I really like JJ tubes for new glass. Old stuff? Right now I have some used 50s rca in there. V2 doesn't seem to care about being a noisy tube. V1 might need to be selected for low noise.

Lots of people seem to prefer lundahl for the transformers.