More: Linkwitz Transform Circuit Questions (1 Viewer)

[Dan M~]

I'm looking at beginning an LT circuit (I have read all the LT pages and downloaded the spreadsheet... and think I understand it) and have a few questions...

1) Has anyone found a good +/- 15 Volt power supply that is readly available in the US?

2) Those that have built/are building LT's, what suggestions do you have for someone just starting out?

3) More ?'s to come, I'm sure...


Thanks.

 

[Anthony_Gomez]

You may want to chew through this thread:
http://www.hometheaterforum.com/htfo...light=linkwitz
It is the Odyssey of when I built a handful of LT's for HTF members.

 

[Dan M~]

Hi Anthony,
Yes, I followed that thread and thats how I became aware of a P/S problem. I was wondering if anyone found a good solution since that project transpired. I(we) are looking into using a wall-wart type 24-36V supply and creating our own +/- 15V from that. I would hate having to jump through that hoop if a simpler, yet cost effective, solution had been located.
I'm curious of how the folks that participated in your offer have found the LT circuit to work for them? Have they had any problems in fine tuning the R values to achieve the target response?
It's been very quite since the mentioned thread scrolled off daily screen. Maybe everyone is just sitting back and enjoying the bass!

 

[Jack Gilvey]

I think many ordered the circuit with Tumults, Stryke AV's, etc. in mind, so they're still waiting on woofs. I did use mine briefly with a sealed Adire DPL12 and it works as advertized. Not very earth-shattering with that combo since it's so flat and deep in-room already.

 

[Jonathan M]

Dan,
Have you checked out Rod Elliott's site at ESP? He has a small +/-15V power supply project there (for preamps etc.) that would be suitable. It'll run off a 12-20VAC wall wart or a 15V transformer etc..
The actual circuit is really simple. Just a diode bridge, filter caps and rectifiers (LM7815/7915). It could be easily put together on prototype board and should cost less than $10. He offers PCBs as well (including the LT PCB) if you want to go that route. I think Anthony used his boards when he built them (and he made a really great job of it, judging from the pics posted)

 

[Anthony_Gomez]

Dan, I successfully used +/-12 volts (Rod even said it was fine...he actually aludes to this when he says something like "if you only have a 12-14Vac adapter, then use the XXX regulators")
I bet their web page is out of date (at the time, I bought out all of their stock and they were a surplys buy-out), but http://www.alltronics.com/wall_transformers.htm has listed the ELPAC POWER SUPPLY that I used.
As Jonathan (thanks) mentioned, Rod has some powersupply PCB's (which I have also used). You can get both boards from Rod and only pay shipping once.
Also, EVERY piece that dictates the "boost" circuit was hand measured to meet the theoretical values. For the most part I stayed within 1%...though on a few occations, I had to go "as high as" 2%

 

[Dan M~]

Thanks everyone,
I'll look into it some more.
BTW, I'm glad everyone likes the LT circuit!
Now, has anyone found a good 600 watt sub amp, with no fan (or a very quite fan), and auto power on for around $300??

 

[Dan M~]

NEW UPDATE
My Personal Circuit Designer has developed an LT circuit that incorporates most of my desires. We would like feedback from those of you that have experience in this stuff. Please chime in with comments.
Features...
External 24-36VDC Power Supply (Wall Wart)
Extra Power-filtering Capacitors
Clipping Detector LED
Dual Channel Input
Power LED
0/180 degree Phase Switch
Power/Bypass Switch
See the following links....
Schematic Link
Layout (Top)
Thanks for looking and for any help you can pass along.
Edited: To fix phase typo.

 

[Brian Bunge]

Dan,

Shouldn't that be a 0/180 degree phase switch?

 

[Dan M~]

Brian,
Yep:b , I edited my post.
Anything else???

 

[Dan M~]

Bump...