K&K Audio / Lundahl Transformers

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For Sale! Cheap!

99.178.170.55

Posted on June 4, 2016 at 09:00:57
KevinC
Manufacturer

Posts: 2897
Location: NC
Joined: April 19, 2001
I am cleaning up my work benches and the following have emerged from among the dust bunnies:

3 x Tent Labs 11.28960MHz low jitter oscillator module
1 x Tent Labs 16.93440MHz low jitter oscillator module

SOLD


2 x used, tested LL1689AM/PP line output transformers
These can be used to make a very special sounding headphone amplifier. Circuit found here: http://kandkaudio.com/images/PP%206H30%20headphone%20amp.pdf

$299 + shipping


2 x used, tested LL1689AM/PPZ line output transformers
The "Z" on the end of the part number means that there is no added "air" gap, although there is one, in any case, due to microscopic roughness on the C core halves' surfaces. This results in maximum inductance for this type and size of core.

$299 + shipping


Kevin Carter
K&K Audio
www.kandkaudio.com

 

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RE: For Sale! Cheap!, posted on June 5, 2016 at 14:13:03
nerdorama
Audiophile

Posts: 427
Location: Seattle
Joined: February 2, 2002
Hi Kevin,
It appears that the LL1689's, either pair, might be good for a balanced line stage similar to the one on Lynn Olson's page. What might be the advantage to the "Z" version, if any in the real world? Can I assume that higher inductance might help it to match better with a tube of somewhat higher plate resistance than the 5687 family tubes in Lynn's circuit? I've had a long term interest in this sort of line stage as my power amps that have used balanced PP transformer coupled stages have been very pleasing. I don't see any specs for the "Z" version in the datasheets. Any idea of the primary inductance? How much more closely would the tubes need to be matched with this version?
Thanks,
John
De gustibus non est disputandum

 

RE: For Sale! Cheap!, posted on June 5, 2016 at 17:08:55
KevinC
Manufacturer

Posts: 2897
Location: NC
Joined: April 19, 2001
There is a minor increase in primary inductance that in my measurements of 4 transformers back 10 years ago amounted to about 15-20%, thereby reducing the DC current tolerance to about 4mA.

Kevin Carter
K&K Audio
www.kandkaudio.com

 

RE: For Sale! Cheap!, posted on August 15, 2016 at 16:01:06
Wojciech
Audiophile

Posts: 1090
Joined: June 23, 2009
Kevin
Could I modify the phone amp circuit to use it as a active RAKK MKIIIdac stage after passive board ? I have the first generation PCB for an active stage ... and not so much space inside the chassis...

 

RE: For Sale! Cheap!, posted on August 15, 2016 at 16:07:22
KevinC
Manufacturer

Posts: 2897
Location: NC
Joined: April 19, 2001
Which phono amp circuit?

Kevin Carter
K&K Audio
www.kandkaudio.com

 

RE: For Sale! Cheap!, posted on August 15, 2016 at 17:55:15
Wojciech
Audiophile

Posts: 1090
Joined: June 23, 2009
:) headphone amp circuit actually ... sorry Kevin I didn't give the idea much of thinking process basically I wonder If I could implement those 1829 AM trans as an output transformer of a basic active board mKI circuit with possibly different valves like 5687 variety. I would like to keep 1674 trans as an I/V stage just like Audio Note does it .

 

RE: For Sale! Cheap!, posted on August 15, 2016 at 18:25:22
KevinC
Manufacturer

Posts: 2897
Location: NC
Joined: April 19, 2001
You could use the LL1689 as an output transformer for your board, although it's obviously the "wrong" kind of transformer for a parafeed circuit. Several changes will be necessary to make the board useful in a series feed circuit.

Kevin Carter
K&K Audio
www.kandkaudio.com

 

Sold: 2 x used, tested LL1689AM/PP line output transformers, posted on August 16, 2016 at 05:01:23
KevinC
Manufacturer

Posts: 2897
Location: NC
Joined: April 19, 2001
nt
Kevin Carter
K&K Audio
www.kandkaudio.com

 

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