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Interstage for a 10 /10y/801/801a tube

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Posted on October 15, 2002 at 21:24:17
JeLL-O
Audiophile

Posts: 93
Location: Bangkok Thailand
Joined: September 30, 2002
Kevin,

The LL1660 has been recommended to me by Thomas Mayer for use as an interstage to couple the 10 tube as a driver to an output tube.

The LL1660 is normally gapped for 18ma. He says to use the LL1660 that is gapped for 25ma. (1+1+1+1:2.25+2.25). I look at the specs and it shows at connection Alt S. , freq resp to be 25-40KHz, 14k source impedance (1:1.125)

The Lundahl specsheet shows LL 1671 /30 ma as the high current version of LL1660.(1+1+1+1:2+2). Can I use this instead? Specsheet show at connection Alt S, freq resp is 30-30khz but only at 3k source impedance?

I ask coz i already have the LL1671 in my parts bin and wanted to use it if at all appropriate.


JeLL-O

 

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Re: Interstage for a 10 /10y/801/801a tube, posted on October 16, 2002 at 04:46:16
KevinC


 
I think that Thomas Mayer's recommendation is still the best one. The LL1671/30mA does not have a high enough primary inductance to work well in the lower frequencies with the ca. 5000 ohm plate impedance of the 10. The higher inductance of the 1660 makes it a better choice.

Kevin

 

Re: Interstage for a 10 /10y/801/801a tube, posted on October 21, 2002 at 02:49:44
zan73@yahoo.com
Audiophile

Posts: 43
Joined: October 21, 2002
Hi, I already have at home a couple of LL1660/10 and few 10Y I'd like to use with a TI. It seems to me this TI is not enough for a 10Y (if used at 1:2.25 the H s too low; or if used at 1:1.125 the A is too low).
I guess I should buy another one, as you said, like the 1660/25...
Am i (sad reality) right?

Btw, has anybody already experienced a 10Y driving (TI or choke) an 845?? I'm just going to...

And another question: having a 4 Ohm speakers, what's your suggested configuration for the LL1620/90 (A or B?)???

Cheers and keep going, this forum is as great as Lundahls' (almost:-))! D

 

Re: Interstage for a 10 /10y/801/801a tube, posted on October 21, 2002 at 03:31:50
KevinC


 
I'm not sure I wouldn't try it using connection alternative T. You'll lose a bit on the high end due to the highish (ca. 5000) plate impedance of the 10, however, you are correct that the LL1660/18mA (stock item)or 25mA, 30mA, 36mA, or 40mA (all special order items) would be better choices ultimately in connection alternative S.

Assuming that you are planning the reflected load to be 6K, then connection B is the correct choice.

Have fun building!

Kevin

 

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