[DenverW]

Cool!

How do you choose the caps, the bigger the better, or there are some specs that you have to follow?

For the crack, I took into consideration the cost, reviews of the capacitor, and the size. Since the output caps are 100uf (although you can go down a but, though that starts getting bass roll off) they're pretty huge, and require some creative mounting options in the base. I ended up going with the kzk white line tubes because they fit, were reviewed well, and were pretty cheap. Since it doesnt look like i'll be getting those, I'll probably switch to the panasonic ezp line, because they're small, easy to get, and inexpensive. The mundorf line is pretty popular, but the cost is pretty high. If I was going to spend over 100 for a component, I figure I should probably just sell the amp and order a crackatwoa instead.

For my mainline I ordered Auricap XO caps, and bypassed them with really inexpensive FT-3 russian teflons. I didnt mind spending a bit more here, as this is already my endgame amp.

 

[Bullpride]

Buying a tube tester would be too costly an option to just verify a few tubes. Send them to a friend with some tester if you can, or there is nothing really you can do.

Buy tubes next time from some reputable sellers...the most important thing - don't buy tubes without measurements.

These appear to have measurements, though I have no idea if they are legit or good.

 

[cddc]

These appear to have measurements, though I have no idea if they are legit or good.

The specs for 12AU7 is 2200 micromhos, so you have (1465, 1483) / 2200 = (67%, 67%) of 100% NOS

The specs for 6080 is 7 mA/V, so you have (5.55, 5.90) / 7 = (79%, 84%) of 100% NOS

 

[Bullpride]

The specs for 12AU7 is 2200 micromhos, so you have (1465, 1483) / 2200 = (67%, 67%) of 100% NOS

The specs for 6080 is 7 mA/V, so you have (5.55, 5.90) / 7 = (79%, 84%) of 100% NOS

So I got used and not NOS. When I email him, I don't believe I mentioned I wanted NOS specifically. That's on me and not him.

 

[attmci]

These appear to have measurements, though I have no idea if they are legit or good.

That's a 12AX7 according to the label on the box.It's amplification factor (100) is 5 time more than that of a 12au7 (~20).

 

[cddc]

He bought a Tung Sol 12AU7 Black Glass, I guess the box was initially used for 12AX7, but now it's used for his 12AU7.

The 12AU7 is very weak for sure, only 67%.

 

[attmci]

He bought a Tung Sol 12AU7 Black Glass, I guess the box was initially used for 12AX7, but now it's used for his 12AU7.

The 12AU7 is very weak for sure, only 67%.

I love/enjoy to use the BG TS 12au7 tube on my Crack.Especially with a 5998.

 

[cddc]

For the crack, I took into consideration the cost, reviews of the capacitor, and the size. Since the output caps are 100uf (although you can go down a but, though that starts getting bass roll off) they're pretty huge, and require some creative mounting options in the base. I ended up going with the kzk white line tubes because they fit, were reviewed well, and were pretty cheap. Since it doesnt look like i'll be getting those, I'll probably switch to the panasonic ezp line, because they're small, easy to get, and inexpensive. The mundorf line is pretty popular, but the cost is pretty high. If I was going to spend over 100 for a component, I figure I should probably just sell the amp and order a crackatwoa instead.

For my mainline I ordered Auricap XO caps, and bypassed them with really inexpensive FT-3 russian teflons. I didnt mind spending a bit more here, as this is already my endgame amp.

Oh boy...you are really into this DIY hobby not too long ago you built a Crack, now you are building a Mainline....congrats!

Crack uses two 100uf caps for output, and three 220uf caps for its PS. The 100uf kzk white line cap is already huge from @cebuboy 's photo on previous page, is the 220 uf cap even bigger and impossible to fit in the case?

Also, why he added two additional 1 uf caps to the output (1 uf bypassed by 100 uf?), are they too small?

 

[DenverW]

Oh boy...you are really into this DIY hobby not too long ago you built a Crack, now you are building a Mainline....congrats!

Crack uses two 100uf caps for output, and three 220uf caps for its PS. The 100uf kzk white line cap is already huge from @cebuboy 's photo on previous page, is the 220 uf cap even bigger and impossible to fit in the case?

Also, why he added two additional 1 uf caps to the output (1 uf bypassed by 100 uf?), are they too small?

So I actually didnt build my mainline, I got it from another nice head fier. I did replace the output caps inside, however.

For the 220uf PS caps in the crack, I replaced two with higher 470uf non film caps, so they're a bit bigger, but not anywhere near the size of the film caps. The final 220uf PS cap is replaced with a 100uf panasonic film cap, and bypassed with a 1uf mundorf and a .01uf audyn true copper. It was overall inexpensive, as the most expensive caps are the lowest uf. Since I have a choke installed I was able to lower the uf of the final PS cap to 100 with no problems. I suppose I could have replaced all the PS caps, but really only the final one should matter. Its fun, I must say. I enjoy the tinkering, and it keeps me from tube rolling as much since I'm focused on other components!

 

[cebuboy]

Oh boy...you are really into this DIY hobby not too long ago you built a Crack, now you are building a Mainline....congrats!

Crack uses two 100uf caps for output, and three 220uf caps for its PS. The 100uf kzk white line cap is already huge from @cebuboy 's photo on previous page, is the 220 uf cap even bigger and impossible to fit in the case?

Also, why he added two additional 1 uf caps to the output (1 uf bypassed by 100 uf?), are they too small?

you are correct, the 1uf orange lines are bypass for the 100uf output caps.

fitting in a 220uf film cap is kinda not cost effective anymore, so I just bypassed it with a 2.2uf.

getting crowded in there, maybe a cree diode and possibly a choke later if it can fit.

 

[evonimos]

In a similar OTL design, I increased capacitance as much as space allowed for it.
I replaced the 2x100uF(200uF total) electrolytics with 2x680uF(1360uF total), per channel.

So if your enclosure allows for it, go for an array of large value electrolytics, in parallel with smaller value film capacitors and/or ex-soviet PIO.

 

[Bullpride]

He bought a Tung Sol 12AU7 Black Glass, I guess the box was initially used for 12AX7, but now it's used for his 12AU7.

The 12AU7 is very weak for sure, only 67%.

Correct, I believe he reused boxes that did not initially come with the tubes. I bought.

Is it possible the top measurements are 9s and not 4s (1965/1983 vs 1465/1483) though its hard to tell. Lesson learned though. Buy NOS instead of used.

I paid 15 for the 6080 and 40 for the 12AU7 black glass.

 

[Wes S]

Correct, I believe he reused boxes that did not initially come with the tubes. I bought.

Is it possible the top measurements are 9s and not 4s (1965/1983 vs 1465/1483) though its hard to tell. Lesson learned though. Buy NOS instead of used.

I paid 15 for the 6080 and 40 for the 12AU7 black glass.

There is nothing wrong with buying used tubes, as long as you know that when making the purchase and aren't paying NOS prices. Some of my best tubes were bought used.

 

[PsilocybinCube]

Hey everyone, odd question, but where do

So I actually didnt build my mainline, I got it from another nice head fier. I did replace the output caps inside, however.

For the 220uf PS caps in the crack, I replaced two with higher 470uf non film caps, so they're a bit bigger, but not anywhere near the size of the film caps. The final 220uf PS cap is replaced with a 100uf panasonic film cap, and bypassed with a 1uf mundorf and a .01uf audyn true copper. It was overall inexpensive, as the most expensive caps are the lowest uf. Since I have a choke installed I was able to lower the uf of the final PS cap to 100 with no problems. I suppose I could have replaced all the PS caps, but really only the final one should matter. Its fun, I must say. I enjoy the tinkering, and it keeps me from tube rolling as much since I'm focused on other components!

Once you get done tricking out that Crack, just let me know if you want to let it go for cheap so you can build another one

When I return to the office, I will need another amp for listening at work.

 

[cddc]

So I actually didnt build my mainline, I got it from another nice head fier. I did replace the output caps inside, however.

For the 220uf PS caps in the crack, I replaced two with higher 470uf non film caps, so they're a bit bigger, but not anywhere near the size of the film caps. The final 220uf PS cap is replaced with a 100uf panasonic film cap, and bypassed with a 1uf mundorf and a .01uf audyn true copper. It was overall inexpensive, as the most expensive caps are the lowest uf. Since I have a choke installed I was able to lower the uf of the final PS cap to 100 with no problems. I suppose I could have replaced all the PS caps, but really only the final one should matter. Its fun, I must say. I enjoy the tinkering, and it keeps me from tube rolling as much since I'm focused on other components!

Nice find on the Mainline. It is supposed to be a great amp for both low-Z and high-Z headphones.

Obviously lots of mods and considerations involved here. They are much more difficult than swapping tubes, and very likely will bring more sonic improvements.

Is there any benefit to bypass the large caps with smaller ones, like the 1 uf and 0.01 uf caps you and cebuboy used?