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The "Lovely Cube" Headphone Amp (Lehmann Black Cube Linear Clone) - Page 79

post #1171 of 1180

I've finally finished

post #1172 of 1180

Finished with the new power supply with changed voltage regulator? Any conclusions about the final sound?

post #1173 of 1180

Sorry about taking so long to get back.  I ran into an issue.  I can use my shunt PS on either the positive or negative but not both at the same time.  Let me explain!  When I hook up the positive or negative alone it works fine on that channel but if I hook both up at the same time it blows a 1.25 A fuse.  I'm not sure why it does this as the original design only uses around 145ma per channel and and I've been testing the PS with over a 200ma load on each channel without any issues.

 

I haven't give-up on this idea.  I ordered a new pcb for about $4 and I will build it up and play with it.  My current set-up is working good and I don't want to tear it apart and break it.

 

I just built a Millet Maxed with BJT's and it's sounding very good and have The Wire and Marsh Headphone amp waiting.  Half of the fun is the building for me.  But I do love listening as well.

 

 I will post the results.  If someone has a theory of why it's drawing so much current with both the positive and negative supplies hooked up I would like to understand this problem.

post #1174 of 1180

Hi,

where did you connect the new PS? Have you removed all parts of the old one? Don't be shy and post some pic of your wiring.

post #1175 of 1180

I removed the large power supply caps C7 and C8 the two regulators and R9 and R10 I put the + and - voltages on the corresponding pins on the empty regulator pins and then put the grounds on the grounds.  Did I miss something?  I wanted to try it after pulling all the power supply parts but thought it would be easier just to try it on the new board I ordered.  Thanks for any input!

post #1176 of 1180

I received the new PCB and started populating already.  I need to go tomorrow and pick-up a few things.  The new board is a bit smaller but seems fine other than that. It cost about six dollars shipped.
I have damaged builds by doing mods in the past and given myself extra work.  I will play it safe this time.  I'm also going to pick-up some fuses that are slightly bigger.  I have a feeling that everything is okay and just draws more current on start-up than I am calculating.  I need to work this weekend so it may take a little while to finish.

post #1177 of 1180

I built the new pcb and tested it and it has the same issue of over current.  I believe when the PS grounds are tied together on the PCB it causes a direct short on the transformer. The transformer was shaking a bit. I will buy a couple of cheap 15v transformers and I believe all will be fine.  When I hooked up first the neg supply it worked fine. Then I hooked up the positive supply side and it was fine. But together its a no go situation.  I'm just wondering if uses a capacitor and or resistor as a ground lift would work? 

post #1178 of 1180

Saw someone selling the Littlecube Premium in a local forum for MYR500 (about 180USD) and got interested, found this thread. Color me interested, subbed.

 

**edit

Some questions, how does it fare with sensitive cans? I have the JVC HA-S500 that's rated at 32ohm, 106db/1mw and upcoming Rockjaw Kommand rated at 16ohm, 110db/1mw. I have another Goldring DR150 but that's not much of a concern.


Edited by penmarker - 10/12/14 at 1:34pm
post #1179 of 1180

I learned something today.  I picked-up a 0-15, 0-15 transformer and replaced thee 15-0-15 and the problem has been corrected. The two sides are truly separate. On the 15-0-15 it had three wires.

 

Now I need to leave for two straight weeks of work.  I will try to  replace the power supply on the lovely cube again and do some listening tests.

 

Penmaker- It drives my 35 ohm Hifiman cans fine, but I still prefer the Sennheiser HD-600's with it.

post #1180 of 1180
Quote:
Originally Posted by nanchangbob View Post

I learned something today.  I picked-up a 0-15, 0-15 transformer and replaced thee 15-0-15 and the problem has been corrected. The two sides are truly separate. On the 15-0-15 it had three wires.

Now I need to leave for two straight weeks of work.  I will try to  replace the power supply on the lovely cube again and do some listening tests.

Penmaker- It drives my 35 ohm Hifiman cans fine, but I still prefer the Sennheiser HD-600's with it.
that's great!

I pulled from trigger on a pair of HD650 with a dead left channel, going to have a little fun with the lovely cube once I've checked what's wrong with them.
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