[dmcs414]

Hello thread,
 
I've been looking to expand my tube collection for use with my CTH and came across a tube that looked interesting but wasn't sure about it; a Vintage RCA 6CG7 cleartop, for considerably less money than I'm seeing the newer ones go for.  Is there a huge difference between a vintage RCA 6CG7 and one of the newer versions from places like tubedepot which go for $50 a piece?  BTW, you can easily find the eBay listing I mentioned if you search for Vintage RCA 6CG7.  The auction ends in a few hours so I may just bite the bullet and buy the thing.
 
On a side note, if anyone has any other tube recommendations they'd like to make that have particularly good synergy with TPs, I'd be grateful to hear them. Thx!

 

[sachu]

I'd say buy a RCA 6CG7 clear top from a reputable source like Upscale audio or tubedepot with matched triode sections and that has been tested for low noise and microphonics. I have seen a fair few 6CG7 clear tops with microphonics mainly and its rather frustrating.
 
Since its a single tube, its worth spending the extra money.
 
One other tube i really loved with the CTH and orthos including the TPs was the 6N6P. BUt the 6CG7 clear top was always my mainstay.

 

[dmcs414]

Quote:

I'd say buy a RCA 6CG7 clear top from a reputable source like Upscale audio or tubedepot with matched triode sections and that has been tested for low noise and microphonics. I have seen a fair few 6CG7 clear tops with microphonics mainly and its rather frustrating.
 
Since its a single tube, its worth spending the extra money.
 
One other tube i really loved with the CTH and orthos including the TPs was the 6N6P. BUt the 6CG7 clear top was always my mainstay.

Thanks sachu.  I have a few 6N6Ps, older, Russian I believe.  They sound pretty nice to my ears and I plan to keep them.  Just trying to develop a wider selection.  Can you tell by the picture whether this one 6CG7 is legit or not?  It's eBay item # is [size=small]400268714739.[/size]
 

 

[sachu]

Yesh, its a legit tube alright. An older generation tube without the shield.

 

[dmcs414]

Quote:

Yesh, its a legit tube alright. An older generation tube without the shield.

Sweet, I nabbed it.  Only 20 bucks too.  Thanks mate

 

[dmcs414]

Quote:

Sweet, I nabbed it.  Only 20 bucks too.  Thanks mate

 
Edit- Oops, this was meant to be an addition to my previous post, not a new post altogether.  My bad!  
 
As long as we're on the topic of tube rolling and our beloved CTH, how many have you have done the necessary mods to allow the big fat tubes that I believe Smegs had rigged up in his CTH and is it worth the time/investment to use that tube or is there not much of a change between, say, the RCA 6CG7 we've been discussing?

 

[sachu]

Honestly guys, if you want a good mod for this amp, replace the LM7824 IC with a Belleson super regulator. (2A capable one). It should be a drop in replacement.

 

[dmcs414]

Quote:

Honestly guys, if you want a good mod for this amp, replace the LM7824 IC with a Belleson super regulator. (2A capable one). It should be a drop in replacement.

I'll do some looking into that for sure. Thanks!  
 
No thoughts on the mod I mentioned before that allows that bigger tube though?  I'm just basically curious as to what kind of difference it makes. 

 

[sachu]

That was a 6f8g. He was using a national union tung sol round plate one.

Youwill need a 6cg7 to 6f8g adapter that you can get from ebay.

 

[dmcs414]

Quote:

That was a 6f8g. He was using a national union tung sol round plate one.
Youwill need a 6cg7 to 6f8g adapter that you can get from ebay.

Thanks for all the help sachu, but what I'm asking is simpler than that.  Does it sound better, same, or worse in your opinion?  That is, of course assuming you've heard it with that mod and tube.  If not, don't sweat it.  I'm just trying to gauge the difference in sound were I to go that route. 

 

[Pingfloid]

[size=medium]CTH down!

[/size]
 
[size=medium]I have finally received the LM2595 and completed the assembly. It was working and all voltages correct.[/size]
 
[size=medium]After a couple of minutes, the LED suddenly turned RED. I immediately verified the voltages and they were OK, but then R7S started smoking and the +24 and +12 voltages dropped to +20 and +9V approx. Heater and B+ were OK. Then I switched it off.[/size]
 
[size=medium]Q3S and Q5S seem to be crossed. I am going to remove all the socketed IC’s and the 6 transistors from the Rail Splitter for verification. Then I will verify the +24V. If it’s ok, then I will replace the damaged parts from the rail splitter.[/size]
 
[size=medium]I have combined the schematics into one A3 page to facilitate troubleshooting.[/size]
 
[size=medium][size=small]http://dl.dropbox.com/u/46804116/CTHA%20Schematic.pdf[/size][/size]

 

[Pingfloid]

When removing IC1S, the output of the TLE2426 is +12V, so IC2S is still aive.
 
When inserting IC1S, it's output is at +12V, and VG also +12V, but in one minute, R5S/R7S smoke and Q5S/Q3S burn. I am wondering where is the origin of this barbeque.

 

[cfcubed]

It can certainly be frustrating to try to uncover/correct build errors on this tiny PCB.  
When I've tried I've done the "shot gun" approach, replacing many parts, but that's when I've known the cause of the smoke (e.g. a slip w/a test probe).
 
I'm quite busy ATM & will try to look this over over the next several days, perhaps someone that knows better will chime in.

 

[runeight]

Remove one lead of R10E. Replace Q1S and Q2S. Replace Q3S, Q5S, R5S, R7S.
 
Make sure that the Vg point is not actually grounded anywhere.
 
Then try again. This may take a while.

 

[Tribbs]

Quote:

Honestly guys, if you want a good mod for this amp, replace the LM7824 IC with a Belleson super regulator. (2A capable one). It should be a drop in replacement.

I'm game, Sachu.  But I'm unfamiliar... Would someone be so kind as to provide the Belleson reg. part# or link, please? - TIA.