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The "Lovely Cube" Headphone Amp (Lehmann Black Cube Linear Clone) - Page 81

post #1201 of 1215
After many SS amps i end up with LC Premium.
For me its a awesome amp.
The OPAMP rolling also improves the sound and add a good tweaking juice.
Now i'm using the Audio GD OPA-Earth with great results.
post #1202 of 1215

the Lovely Cube can be ordered with a 2nd input, right ?


by the way, anyone here compared the Lovely Cube to the Garage 1217 Project Polaris ?

post #1203 of 1215
Originally Posted by ervstil View Post


Last night i solved the puzzle at last. I have checked all the usual suspects, including the suggestions above every thing was OK. I changed my 627 op amps for another pair. Same thing. Then i changed to a genuine opa2134 in dil package. Dead silent! As it turns out the opamp adapter functioning as an antenna and my  R-core transformer induced hum right in the feedback loop. I verified this by adding a "class a bias socket" and thing got really hummy. I have ruled out this before because i tried different shields and positions of the transformer with absolutely no difference. 


I wonder if a LME49720HA (in metal TO-99 can) opamp would have helped with shielding.

I use one with a TO-99 to 8-pin DIP adapter...

...class "A" biased with a TO-5 type heatsink for an extra margin of cooling.
Edited by Tribbs - 1/5/15 at 7:22pm
post #1204 of 1215

So, now I´m almost finished with my two amps. It tooked some weeks to build them from skratch, but it was a joy. I only used high grade compontents, such as Elna Silmic II, Nichicon KZ Muse, Mundorf, Wima, OPA627AU, PRP9372, Polystyrenes, BYV27-200 with bypassing caps, Audyn True Copper with Teflon bypass caps, Dale 24 step volume attenuator etc.


As I´ve built two amps, maybe someone want to buy one of them!?


Just tell me if you´re interested or PM me.


I also have s spare of most of the parts as it was cheaper per unit to buy bigger quantities, so I can also sell those if someone is interested.



/ Mikael Markstrom


post #1205 of 1215

Can anyone comment on the quality of the DAC chipset used in the Lovely Cube Premium AD available for sale assembled at http://www.alicemagicbox.com/lasercollection/lovelycubepremiumad.html?


The website lists the chipset as ES9023. I'm trying to decide between the Audio-GD NFB-11.32 and the Lovely Cube to drive a pair of Senn HD 650, and I'm wondering what kind of disparity in DAC quality there is between the two. The NFB-11 uses the ES9018. Initially I thought the 9023 must trump the 9018. Higher model number means better right? But then I've seen reports that the 9018 is actually a much higher quality chipset. So I'm just wondering if there really is that much of a difference, or if the 9018 is just more expensive without really being any better.

post #1206 of 1215
She's alive!

Finally completed my LC kit with the following component swaps and modifications:

1) Installed a Hammond (1182M15) 80VA Torroidal Transformer [barely fits] (w/500mA slo-blo fuse).

2) Replaced C305 & C306 4700μF 50V capacitors with genuine United Chemi-Con (16M6799).

3) Replaced LM317T/LM337T (Q301 & Q302) with genuine Fairchild regulators (58K8936/58K8937).

4) Replaced LM317T/LM337T R2 1KΩ resistors (R306 & R308 [R308 on schematic is mislabled] ) with two parallel Zener diodes (18C6023) in each position for lower resistance and safety.

5) Replaced the LM317T/LM337T Cadj capacitors, C308 & C311, with genuine Sprague 10μF tantalums (30C8841).

6) Replaced C103, C104, C203, C204, C313, C314, 470μF 25V capacitors with genuine Panasonic FC (80K8337).

7) Replaced C101,C102 & C201, C202, 1.5μF 200Vdc and 0.022 μF 600Vdc input caps, with SoniCap Gen I (cheap & good enough).

8) Replaced opamp with genuine Texas Instruments LM4562HA with TO-99 to 8-pin DIP Adapter and TO-99 heatsink.

Worked perfectly on the first smoke test - and sounds great!

Thanks go out to the many "BlaBlaBla" posts earlier in this thread for sharing his technical knowledge, experiments, troubleshooting and suggested upgrades. Kudos!
Edited by Tribbs - 1/15/15 at 11:25am
post #1207 of 1215
All lies! I need picture proof!
post #1208 of 1215

I can not get the pictures, appears Your account does not have the required permissions to access this page.

Edited by Laybar - 1/16/15 at 12:35pm
post #1209 of 1215

I can not get the pictures, appears Your account does not have the required permissions to access this page.

post #1210 of 1215
Thread Starter 
Originally Posted by Habibelhabab View Post

Forgot to share this in previous post:

I have reworked the schematic with correct part naming (much easier to work with)



Thanks! I've updated the first post with the correct schematics.

post #1211 of 1215
Originally Posted by Laybar View Post

I can not get the pictures, appears Your account does not have the required permissions to access this page.

You have low post count. Try uploading them to imgur.com perhaps until you're allowed to post pictures in the forums.

post #1212 of 1215
Originally Posted by sunneebear View Post

All lies! I need picture proof!

Your post was my bad luck!

Today, I was going to take pictures. But, when I turned on the amp the 500mA mains slo-blo fuse blew. Replaced, and immediately blew the second one to. I don't have time to troubleshoot until next week. Any suggestions?

She was working fine for a total of about 3 hours.
Edited by Tribbs - 1/17/15 at 1:46pm
post #1213 of 1215

One thing I tas noticed it that many people using the attached sockets with screws for connection of the wires in their amps - those sockets is the first thing I throw in the trash bin. Many are telling they use expensive Mogami wires, and then assembled them in the amp with plain steel sockets - the chain is not better then the weakest link!! It´s very preferable to solder the wires directly to the board. And for the difference in wiring, I don´t think there will be a huge difference between for example Mogami and standard ogygen free copper wires when using them so short in the amp.


Another thing I struggling with for the moment, is to find high quality 1/4 inch/ 6,35 mm headphone sockets for soldering. I have bought several different types, but no one will be gold plated, and one person claimed his headphone sockets were made of copper, but when I get them, they were not goldy or copper. Just shiny blank so I´m not sure if they´re just steel or nickel. Or maybe they are made of copper, but are nickel or chrome plated.

They are not magnetical, so at least that´s good.


How important is it to use gold plated headphone connectors? I know gold plating are used to minimize the risk of oxidation.


And do someone know where to buy gold plated stereo headphone sockets? I´ve found gold plated mono sockets, but they need to be stereo.



/ Mikael Markstrom

post #1214 of 1215
Originally Posted by mikaelmark View Post

And do someone know where to buy gold plated stereo headphone sockets? I´ve found gold plated mono sockets, but they need to be stereo.

I think gold plated jacks are cheap - no brainer.

The gold plated jacks that came with my LC "deluxe' kit (deluxe kit no longer available) look like these:

Neutrik NRJ6HF-1-AU http://www.neutrik.us/en-us/plugs-jacks/slim-jacks/nrj6hf-1-au

In stock at Mouser:

Mounting hardware must be ordered separately:
NRJ-NUT-B (black plastic)
NRJ-NUT-MK (metal knurled)
NRJ-NUT-MS (metal)
NRJ-NUT-R (red plastic)
NRJ-WB (black washer)
Edited by Tribbs - Yesterday at 12:39 pm
post #1215 of 1215

Thank´s for your teply, Tribbs!


It´s a shame I can´t found those gold Neutrik here in West europe, shipping from Mouser is about $25.


It seem´s the shiny connectors that´s not gold plated is made of bronze with tin and selenium(?) plating:





/ Mikael Markstrom

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