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PP 45

202.156.2.138
Posted on October 26, 2002 at 20:56:39
45drive45
Audiophile

Posts: 132
Joined: March 3, 2002
 Hi there,

i am gathering parts for a PP45 either Ralph Power design or Kurt's. Either uses thr 1660/PP interstage. What actually the difference between the PP version and the SE ones. The SE comes with dc current rating and I have used the 10ma in few of my SE amps. Are there any dc ratings for the PP version.

Planning to be able to use either 2a3's or 45 or even vt25 for this PP amp.

Driver would be either 6hp30 or ecc99. Heard good things about this tubes.

 

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Re: PP 45, posted on October 27, 2002 at 05:49:14
KevinC


 
There is no other difference than the gap that is introduced between the two halves of the C core when the transformer is manufactured. The wider the gap, the greater DC current tolerated prior to core saturation and the lower the primary inductance. You can use the 10mA version for PP service at the loss of some very low bass extension, but you can't use the PP version with a single ended driver stage without serious loss of bass.

Kevin

 

Re: PP 45, posted on October 30, 2002 at 16:33:02
shane


 
Hi Kevin,

Kurts PP45 uses a parallel feed ECC99 driver that is CCS loaded, it doesnt use the primary of the IT to load the tube. When he measured LF-3dB it was around 20Hz and that was with 0.33uF parafeed cap!, I remember one of his posts saying it was good to 10Hz with 2uF.

Thanks for your reply to my question regarding loading the secondary of the LL1660 from the other forum, the info was regarding this amplifier here.

45drive45, what value of resistance would you use to load the secondary?.

thanks,
shane

 

Re: PP 45, posted on October 31, 2002 at 06:43:32
45drive45
Audiophile

Posts: 132
Joined: March 3, 2002
 To answer the question, no idea at the moment. Have not gathered all the parts for the amp but I am sure that i want to build it. And considering that its pretty simple to try different values, I will not think about it for now until I am done with the amo and then tune by ear. It is true though that if you use too large of a resistor, the sound just dies on you.

 

Re: PP 45, posted on October 31, 2002 at 12:53:14
Kurt Strain


 
I removed the 47K IT secondary load resistors in my PP45. It now sounds better with it removed after all settled in. It also seemed to add a watt more power as it pulls the 45 grids stronger without this load. I enjoy it a lot.

Kurt

 

Re: PP 45 - thanks! (nt), posted on October 31, 2002 at 16:42:51
shane


 
thanks man, thanks!.

shane

 

Re: PP 45 - thanks (nt), posted on October 31, 2002 at 16:44:13
shane


 
.

 

Kurt one question.., posted on November 10, 2002 at 03:58:04
C.Y
Audiophile

Posts: 345
Location: S.Korea
Joined: September 7, 2002
 My phono stage of your design has been there uncomplete..could you tell me the CCS that you used on the 6ER5/6GK5 phono stage?
C.Y

 

Re: Kurt one question.., posted on November 15, 2002 at 12:51:48
Kurt Strain


 
It had two PNP's like a C4S except I changed the top LED to a 5.6V zener diode bypassed with a 10uF tantalum cap. The lower LED is changed to a 2.2K resistor. A small 1uF polycarbonate cap is used to "bootstrap" from lower PNP's base to upper PNP's emitter. A 2K resistor is used to set the 2.5 mA bias in the upper emitter. The cap choices are not that critical.

Kurt

 

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