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The "Lovely Cube" Headphone Amp (Lehmann Black Cube Linear Clone) - Page 74

post #1096 of 1416

Personally, i think das PCB has a lousy layout. But it is small - advantage.

 

The different voltage comes from the LM337/LM317. Read their datasheet and google how they work. Some people like me have used resistance trimmers to equal them ( http://szcanyi.en.alibaba.com/product/307861290-50332208/3296W_103_trimmer_resistor.html ).

 

And where should i start... have you measured the DC-offset before connecting your headphones?

post #1097 of 1416

Quality kit


hello
I been reading this thread and think I am very interested in building one of these headphones amplifiers from a kit. But in one person's response to a question on this thread they said and I paraphrase, so you bought a kid on eBay that means you may not have gotten quality parts match components and things like that.


 So does anybody here have recommendations for a quality kit?


Also is this thread one of a long line of clone threads? I am a newbie and will need PAC, headphone amp, and possibly when he a linear power supply if there is some way of getting one at less than audiophile prices. I mean repurposing one not intended for audiophile use or building a kit.


Is there such a thing as a audiophile level of soldering? And if so is there any information on these forums or anywhere else on the web that somebody here may know about?


Edited by bbmiller - 2/5/14 at 10:33am
post #1098 of 1416

hi, there is only junk kits like this one. or just search eBay for "lehmann kit". that's why I did a part list here; post #1089. the cmponent numbers are from the PCB.

 

ask the seller for buying only the PCB only, or buy the kit and put the component package to the kids or recycling. and use the parts you want.

 

good luck/Amir

post #1099 of 1416

So if I remember what you said you have to match the active components and make sure that matched. So is what you're saying that these kits aren't of a quality that you know the active components have been matched and you have to take it on luck and maybe by active components twice and some how  figure out if that matched?

 

Well that leaves me thinking that maybe when these manufacturers charge you over $1000 to build one they are actually giving you something in the implementation that really must be worth something maybe not over $1000. But something.


Edited by bbmiller - 2/6/14 at 12:51am
post #1100 of 1416

Hi bbmiller!

 

The kits on ebay are quite ok, but don't think you can build a high-end headphone amplifier for less than 25$ - also if you are not interested in DIY, buy a Matrix clone or a lovely cube.

It can be really difficult to find a mistake in a circuit ;)

 

Here is an example of a better pcb:

http://www.ebay.com/itm/High-end-stereo-Class-A-headphone-amplifier-PCB-1piece-/221131370084

 

I would suggest you buy a full kit, so you get all necessary parts like headphone jacks, cooling parts, LEDs... etc.

Afterwards you can start to evaluate what parts you would like to use. I recommend to swap all parts which are in the signal path.

Especially BC550/560, BD139/140, opamp, all(!) capacitors

Match the resistors, test the diodes and buy a high quality Alps porti...

 

When you have made your list, you will know exactly what to buy additionally. The thread is full of suggestions.

Be sure to check your PCB and your parts before soldering them. The pcb won't allow you to exchange parts too many times.

I think you can realize an amp for about 80-130$ - depends on what you are planing to build.

 

 

PS.: If you would like to make it perfect, then think about using resistor trimmers or a dedicated power supply like posted before: http://www.head-fi.org/t/501046/the-lovely-cube-headphone-amp-lehmann-black-cube-linear-clone/1035#post_9505128

 

PPS: Highend soldering technics? Make a fire by moonlight and sacrifice a lamb.... nah. There is only one important thing about soldering: Make solid and clean connections.


Edited by nippon - 2/6/14 at 9:02am
post #1101 of 1416
Quote:
Originally Posted by nippon View Post
 

Hi bbmiller!

PS.: If you would like to make it perfect, then think about using resistor trimmers or a dedicated power supply like posted before: http://www.head-fi.org/t/501046/the-lovely-cube-headphone-amp-lehmann-black-cube-linear-clone/1035#post_9505128

 


Well - if a purchase I make from another member  goes through these further questions may be more for my own edification than anything else. But would it be very easy to repurpose a linear power supply not intended for audiophile use if it's the right voltage and save a lot of money that way. Is there something about building your own linear power supply which makes it superior to repurpose thing one not intended for audiophile use.

 

resistor trimmers - do you mean resistors that are really potentiometers or have potentiometers in series with them? Could you link me to a picture or include one in your reply?


Edited by bbmiller - 2/6/14 at 10:13am
post #1102 of 1416

Some people think that the power supply of this circuit is one of his weakspots. When i use my clone, i can't here any hum or noise because my phones mostly got high impedance. For example when i once purchased a Audio-Technica ATH-M50, which has a very low impedance and high sensitivity, it was impossible to enjoy listening. Hum and noise everywhere...

The other head-fi member and i talked a bit. After he got rid off the LM317/LM337 regulators, his clone went calm he says.

 

There are some solutions which are quite nice and using these regulators, but this power supply is very primitive. For myself i'm sure the original has some better way to provide 2x +15V DC, but i have to find somebody who let me open his 1000$ amp ;)

Just to name a better power supply: The objective O² is dead silent, even when a very cheap wallwart (which i can hear hum :blink: ) provides the AC power .

 

Kind regards,

nippon


Edited by nippon - 2/6/14 at 9:58am
post #1103 of 1416
Quote:
Originally Posted by nippon View Post
 

 I recommend to swap all parts which are in the signal path.

 

Does slotting means docketing? If so whose or what sockets?

post #1104 of 1416
Quote:
Originally Posted by bbmiller View Post
 

Does slotting means docketing? If so whose or what sockets?

?

 

There is only one socket: The DIP-8 OPA (operation amplifier)... slotting...docketing :popcorn:

From which country are you?

post #1105 of 1416

USA

Perhaps I should explain. I do all my posting through speech dictation I have a spelling disability. And if I am anxious or want to make a post quickly I sometimes don't proof it properly. I do not think that was a US expression it was just my poor lack of proofing because I was doing a quick post that I was doing being hungry at the time.


Edited by bbmiller - 2/6/14 at 1:13pm
post #1106 of 1416

Okay, I understand. I just thought there is a little chance that you are from Germany and i could explain some things very easy to you in german :)

If you need some advice in picking parts or choosing a kit on Ebay - just send me a private message. Definitely I am not a expert, but when I build my clone, I did so many mistakes from which i learned a lot about this circuit.

 

Kind regards,

nippon

post #1107 of 1416
Quote:
Originally Posted by nippon View Post
 

 

I would suggest you buy a full kit, so you get all necessary parts like headphone jacks, cooling parts, LEDs... etc.

Afterwards you can start to evaluate what parts you would like to use. I recommend to swap all parts which are in the signal path.

Especially BC550/560, BD139/140, opamp, all(!) capacitors

Match the resistors, test the diodes and buy a high quality Alps porti...

 

 

now that I established I may need a little understanding sometimes with my spelling not immediately being understandable let me venture in trying to spell things right and ask to other questions.


So what I think you are saying is not to use any parts in the single path even though they come with the kit? From the above would you all so only use 1% resistors if you want to do things right and all your projects? And if you changed out all the parts in the single path are there rules of thumb (general guidelines) as to what parts in the single path would be better than the parts they give you?


Also as a general project guideline for all your projects would you say pinouts on op amps are generally the same? Can you read about the latest and greatest op amps and think most of them will be compatible as better ones for your projects and even to swap out in your own equipment? Are there things about op amps other than equivalent pinouts which will make them not compatible in equipment?

post #1108 of 1416

When you order one of the cheap kits, you will maybe get a good one. But there is a risk of getting not the best parts for the circuit.

Just one example: When I get my kit, I didn't get the BC550/BC560 transistors. They sent the nearly equal BC546/BC556. But there is one major difference - only the BC550/BC560 are made for low noise operating

If you buy a cheap kit - you get cheap parts - so you will get cheap sound!

 

And for the OPA Question:

You have to read the datasheets for every single one. Some are nearly the same as OPA2132 or OPA2134 are (which are quite good for these headphone amplifier).

But there are also other pin models. These are OPAs made for audio amplifying, but they are only a small part in the family of operation amplifiers, which are used for nearly any circuit you can imagine.

 

I recommend you to start with a smaller project like the Cmoy or the Objective O². If you really want to build this type of amplifier, please read the thread.

 

Kind regards,

nippon

post #1109 of 1416

Is the performance of this identical to the black cube linear?

post #1110 of 1416

Yes and no :)

Read that thread from post #8 to #15

http://www.head-fi.org/t/545225/lehmann-audio-black-cube-linear-headphones-amp-pictures#post_7364890

 

It's a copy and if you are going to build it yourself, you can influence how good the result is.

Maybe it is better to compare it with other DIY amps. My DIY LC clone sounds way better than my Objective², which has clearly more power than my Cmoy.

I'm allready planing to build another clone with a better power supply and higher quality parts.

 

In my opinion the circuit is nothing special. If your intention was to ask if you can buy the same "high-end" product for less money, then the answer is no.

You have to pay more money or invest some of your spare time in that amp (remember: time is money).

 

 

(BTW: The Matrix M-Stage websites says that their amp is nearly identical to the Black Cube Linear regarding to the technical information)

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