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Old 20th June 2009, 01:57 PM   #401
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Yes, I changed the input coupling cap with metal film cap, which can minimized the pop sound.
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Old 20th June 2009, 02:15 PM   #402
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Quote:
Originally posted by MikeHunt79

code: 233-5134 ?.44 ELC coil inductor,10uH 2.3A

Col found it, so credit goes to him.

The same manufacturer does produce a 3A (I think) inductor also, which should also be stocked by RS. I can't look it up tho as the RS site appears to be down!

The 3A inductors do have a larger diameter, so I'm not sure if they'd fit the Lepai, but it may be worth a go.



Mike,

Today, I try to find toroids. I can find 10uH, 2A and 20uH, 3A only .

Accordingly official specification should use 10uH, 3A., which toroid is more suitable for this amp.
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Old 20th June 2009, 06:26 PM   #403
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I've just added some 2.2uF film caps, I'll post pics in a bit.
Quote:
Originally posted by panda360


Mike,

Today, I try to find toroids. I can find 10uH, 2A and 20uH, 3A only .

Accordingly official specification should use 10uH, 3A., which toroid is more suitable for this amp.
I'm using a 10uH 2A inductor, not a toroid, but it sounds good to me and is better than the original.

I'd go for the 10uF 2A toroid.
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Old 20th June 2009, 09:31 PM   #404
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Quote:
Originally posted by magixz
i worked out the opamp and power circuit for the Lepai amps...
I have a few... all running the same opamp and similar tone control (Only resistors different for different chip's input impedance)
Any software which can sketch it out?

Realised the opamps are there just to create a low impedance output to the tone controls so it will not affect tone control. (correct me if i am wrong)

There are 3 sets of signal coupling caps.
They are are
(1) 2x 10uf after volume pot before op amp,
(2) 2x 10uf after op amp to tone control,
(3) 2x 10uf or 1uf after tone control to chip.

Set 1 removed DC before Opamp, but another circuit adds in DC again.
Set 2 remove DC before tone control.
Set 3 remove DC before the Amp

They are all labeled as 2.2uf on the board.
Shouldn't we change the (3rd) set just before the chip instead of the one before the op amp?
This is pretty much I have just done today:
Click the image to open in full size.

The 2 blue caps on the left are 2.2uF film caps, and they are wired to the holes in the PCB where the "(3) 2x 10uf or 1uf after tone control to chip. " caps go.

The extra wires and switch allow me to bypass the tone control altogether which is useful for me at least.

I would be interested to see some sort of sketch of how the tone controls work, have you tried eagle at all?

http://www.cadsoftusa.com/
http://en.wikipedia.org/wiki/Eagle_(program)

The free version is all you need, with few restrictions for small circuits like the Lepai.

I was thinking the tone controls could be modified into some sort of crossover, making 2 of these amps ideal for a pair of bi-amped 2-way speakers.
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Old 21st June 2009, 02:25 AM   #405
msj965 is offline msj965  United States
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Default Hello:)

Hi There!
Just wanna ask a big big favor to all of you guys (as a newbie) .Pls. can you check this part number for me?not sure what toroid to use.On the web site of DIGIKEY.com search on this part number m9981- nd and 732 - 1416 - nd, let me know so i can buy it here.
Thanks much,
Ann
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Old 21st June 2009, 10:00 AM   #406
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Quote:
Originally posted by MikeHunt79
I've just added some 2.2uF film caps, I'll post pics in a bit.

I'm using a 10uH 2A inductor, not a toroid, but it sounds good to me and is better than the original.

I'd go for the 10uF 2A toroid.

Mike,

Thank you. I also think the current rating of original inductance is not enough.


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Old 21st June 2009, 02:02 PM   #407
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Default Inductors for output filters

Tripath definitely suggests toroidal inductors with iron-powder cores as shielded bobbin construction is not as effective for EMI containment.
Powdered iron is regarded to have an higher Q and in our case this is a premium.

http://www.osoelectronics.com/downlo...ng Toroids.pdf

For the smallest toroid suggested by Tripath, Micrometals code is T60-2. This is the toroid provided by 41Hz.com with their kits and require 39 turns of 0.5mm magnet wire.

(A bigger one -with better specs- could be "T68-2 wound with 44 turns of 22AWG wire" according to Tripath technical informations).

As in our case space also is a premium and bobbin inductors are easier to find, we're looking for a good compromise.

Anyway, we need
  • 10mH
  • 3A
  • frequency higher than 1 MHZ
  • coil with high Q and
  • low saturation at high frequency

Unfortunately I haven't a proper meter but it seems to me that the following one could works well.
Any suggestions?

http://cgi.ebay.it/10UH-Medium-curre...kparms=65%3A12|66%3A2|39%3A1|72%3A1229|240%3A1318|301%3A0|293%3A 1|294%3A50
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Old 21st June 2009, 07:02 PM   #408
col is offline col  Australia
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Calamaro,
Quote:
Unfortunately I haven't a proper meter but it seems to me that the following one could works well. Any suggestions?
That looks like it would do the trick. At 24mm it would be very close to the top of the case though. You would have to be careful with insulation. otherwise the inductor might arc against the case body. I still think that the 41hz amp6 toroids are the best value. Only problem is winding them, which isn't that hard but is time consuming.

col.
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Old 21st June 2009, 10:02 PM   #409
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Col,

Quote:
I still think that the 41hz amp6 toroids are the best value
You're definitely right. I bought (and wound...) them but my post aim was to find a decent alternative. Thank you for your attention.
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Old 23rd June 2009, 03:22 AM   #410
Jiggen is offline Jiggen  Australia
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Quote:
Originally posted by MikeHunt79
Hey guys, another Lepai arrived today, and it appears to be a little different, I guess this could be Mark 3?

Here's a pic, new (mk3) on the right and my old (modded mk2) on the left:
I'm sorry if this has been answered, but which buyer are you getting the mk3 Lepai from? Thanks.
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