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The "Lovely Cube" Headphone Amp (Lehmann Black Cube Linear Clone) - Page 60

post #886 of 1038
12/1/11 at 8:43am
Quote:
Originally Posted by BlaBlaBla View Post


Yes. It is.

 



Awesome!

 

Hopefully everything is here tomorrow and I can solder it all in. Basically all will be modded except the transistors. I want to change them too but can't find any matched pairs. Any suggestions?

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post #887 of 1038
12/1/11 at 10:48am


 

Quote:
Originally Posted by JiggaD369 View Post



Awesome!

 

Hopefully everything is here tomorrow and I can solder it all in. Basically all will be modded except the transistors. I want to change them too but can't find any matched pairs. Any suggestions?


Stick with new BD139/140 transistors. Do not buy "japanese" old stock because those are fakes (especially on e-bay). BD139/140 by Onsemi, Fairchild, etc... are genuine in 95%.

 

This seller has old matched transistors but somewhat expensive. Youu have to be cautious. Sometimes it makes mistakes. I bought few things without problems.

 

http://www.ebay.com/itm/4-X-MATCHED-ONSemi-MJE243-MJE253-POWER-TRANSISTOR-/150570180071?pt=LH_DefaultDomain_0&hash=item230eae9de7

 

http://www.ebay.com/itm/4-X-MATCHED-ONSemi-BD139-BD140-MEDIUM-POWER-TRANSISTOR-/350237513136?pt=LH_DefaultDomain_0&hash=item518bc855b0

 

I would buy 10 transistors (BD - Onsemi) of each type and measure hFE. Usually, this is good enough for audio. OR you can play safely and buy matched transistors from Banzaimusic. You can send them email about which transistors you need matched. But shipping is expensive so I suggest you buying something from Banzaimusic when you need lots of items.

 

www.banzaimusic.com

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post #888 of 1038
12/2/11 at 4:37pm

Good transistor advices there from BlaBla!

 

Worth trying are also these Hitachi types from the same seller:

 

http://www.ebay.com/itm/4-X-MATCHED-HITACHI-2SB649-2SD669-POWER-TRANSISTOR-/350265318062?pt=LH_DefaultDomain_0&hash=item518d709aae

 

The ones I use comes from an old private stock, but I generally I have rather good experience with the eBay seller in question, also.

 

The pins outlay is identical to the original BD's..


Edited by chetlanin - 12/3/11 at 9:02pm
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post #889 of 1038
12/2/11 at 8:30pm
Thread Starter 
Quote:
Originally Posted by JiggaD369 View Post



Awesome!

 

Hopefully everything is here tomorrow and I can solder it all in. Basically all will be modded except the transistors. I want to change them too but can't find any matched pairs. Any suggestions?


Change one thing at a time and remember to test it between swapping components. You don't want to get into a situation where you change too many things at the same time and make troubleshooting too difficult. 

 

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post #890 of 1038
12/5/11 at 3:16pm

Any suggestions for a good shielded transformer for US house-voltage? I know it's a terribly simple question but There's enough out there that I honestly don't know what to pick. Is 30v secondary windings a good choice? And what manufacturer would be a good choice?

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post #891 of 1038
12/5/11 at 3:59pm
Thread Starter 

You want a transformer that has 2 15v secondaries. If your using the stock metal case you have to make sure your transformer fits. I think a 30VA Toroidal is cutting it pretty close. Anything bigger may be too tall to fit. 

 

 

 

 

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post #892 of 1038
12/5/11 at 7:59pm

I have one brand new, still in factory box, Hammond 182M15 torroidal power transformer


80 VA
30V C.T. @ 2.67A
15V @ 5.34A

 

Diameter = 3.73 in
Height = 1.52 in
Weight = 2.15 lbs

 

I think it would fit in the "Lovely Cube" or Matrix M-Stage (old ver. w/short PCB). 

 

http://www.hammondmfg.com/pdf/5c0024-25.pdf
http://www.hammondmfg.com/pdf/182%20Insert.pdf

 

If interested PM me...


Edited by Tribbs - 12/6/11 at 5:18am
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post #893 of 1038
12/5/11 at 11:20pm

 

Quote:
Originally Posted by Maverickmonk View Post

Any suggestions for a good shielded transformer for US house-voltage? I know it's a terribly simple question but There's enough out there that I honestly don't know what to pick. Is 30v secondary windings a good choice? And what manufacturer would be a good choice?



Hand made 80VA EI core... :)

 

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post #894 of 1038
12/6/11 at 11:44am

I am selling mine - it's with OPA627 bias and the good Telama transformer - only 10 days old and like new - here is the auction if interested:

http://www.ebay.co.uk/itm/140656399470?ssPageName=STRK:MESELX:IT&_trksid=p3984.m1555.l2649#ht_500wt_1413

 

I really love it and it sound awesome with my HD 650 and Shure IEM's - but it's not a good match for my ortho dynamic T50rp - so I am looking for a tube amp instead. Unfortunately I can't afford two good amps :(

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post #895 of 1038
12/6/11 at 3:34pm
Quote:
Originally Posted by lokesen View Post

I am selling mine - it's with OPA627 bias and the good Telama transformer - only 10 days old and like new - here is the auction if interested:

http://www.ebay.co.uk/itm/140656399470?ssPageName=STRK:MESELX:IT&_trksid=p3984.m1555.l2649#ht_500wt_1413

 

I really love it and it sound awesome with my HD 650 and Shure IEM's - but it's not a good match for my ortho dynamic T50rp - so I am looking for a tube amp instead. Unfortunately I can't afford two good amps :(

 

This is real thing...

 

http://gilmore2.chem.northwestern.edu/projects/showfile.php?file=ahammer2_prj.htm

 

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post #896 of 1038
12/6/11 at 4:06pm

Hey guys,

 

Bummer!

 

I finally got my components in today and took about 2 hours to swap everything in.

 

I know I should've done it one component at a time like francis told me but I got impatient last week and desoldered everything I was going to swap out. Big mistake. 

 

When I got done today and turned on the amp, everything turned on fine. NO smoke, no sparks. When I plugged in the headphones, I noticed that the amp was distorting at very high volume (my phones are 600ohm) so something definitely got messed up correct?

 

Then I proceeded to find out how to check voltage on the regulators to see if they were working fine and accidently shorted it so now the amp doesn't work anymore. Ugh!

 

I see that one yellow led turns on while the other doesn't. Could the short have blown other things out also?

 

Does Stephen sell just the PCB itself so I can transfer all t he components on there or am I screwed?


Edited by JiggaD369 - 12/6/11 at 4:08pm
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post #897 of 1038
12/6/11 at 4:41pm
Thread Starter 

Post up a high res picture of your board, top and bottom and indicate the parts you changed. I think part of the problem is your opamp is fried.

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post #898 of 1038
12/6/11 at 5:30pm
Quote:
Originally Posted by francisdemarte View Post

Post up a high res picture of your board, top and bottom and indicate the parts you changed. I think part of the problem is your opamp is fried.



HI francis,

 

Thanks for your help! 

 

I know you told me to be cautious but I had already desoldered the components to be swapped in before you told me to. Rookie mistake!

 

Here are the pics. It weird about the distortion because it would be very distorting if turned up all the way but if the knob was half way it would sound awesome. So it being a opamp problem would be calming since I have extra opamps.

 

The changes are left to right:

 

2x 4700uf/50V big tanks.

LM317/337 w/ 10uf/25v tantalum ADJ caps

4x Panasonic FC 470uf

100pf Polystyrene

3x30 ohm output resistors (FlukeLL method)

 

IMAG0097.jpg

 

https://picasaweb.google.com/lh/photo/Ng22NLK0znjl7_Aofu0BesPL_whp-Nux81KiuQ2TPds?feat=directlink

https://picasaweb.google.com/lh/photo/7R6meOSAmUpHU8lg-4vzEsPL_whp-Nux81KiuQ2TPds?feat=directlink

 

 


Edited by JiggaD369 - 12/6/11 at 5:32pm
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post #899 of 1038
12/6/11 at 5:51pm
Thread Starter 

Unplug it and let everything cool down.

 

I can't tell from you picture but make sure there are no bridges between any solder joints. The ones from the new regulator look almost like they are touching but that can be from the angle of the photo.

 

Leave the opamp out. No headphones plugged in. You might want to use a set of cheapies to test and not your main phones!

 

Do both LED's come on?

 

Make sure the regulators aren't getting super hot.

 

Carefully measure the following.

 

What voltages are you getting across pins 7 and 4 of the opamp socket?

Between pin 7 and Ground?

Between pin 4 and ground?

 

 


Edited by francisdemarte - 12/6/11 at 5:56pm
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post #900 of 1038
12/6/11 at 6:07pm
Quote:
Originally Posted by francisdemarte View Post

Unplug it and let everything cool down.

 

I can't tell from you picture but make sure there are no bridges between any solder joints. The ones from the new regulator look almost like they are touching but that can be from the angle of the photo.

 

Leave the opamp out. No headphones plugged in. You might want to use a set of cheapies to test and not your main phones!

 

Do both LED's come on?

 

Make sure the regulators aren't getting super hot.

 

Carefully measure the following.

 

What voltages are you getting across pins 7 and 4 of the opamp socket?

Between pin 7 and Ground?

Between pin 4 and ground?

 

 


HI francis,

 

Sorry for the stupid question but the meter is supposed to be on 20v - DC correct?

 

If so,

 

Between 4 & 7 = 1.36V

Between 7 & Ground = 0.08V

Between 4 & Ground = 1.27V

 

Only one yellow led comes on. Sound is very distorted.


Edited by JiggaD369 - 12/6/11 at 6:09pm
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