[Zsubbo]

I tough so too about the volume pot, or maybe I'll just use matched resistors. I should get a transformer like this http://www.ebay.com/itm/220V-115v-30W-R-Core-Transformer-preamp-9V-2-15V-2-/120658545276?pt=BI_Circuit_Breakers_Transformers&hash=item1c17cf4a7c too for the project, and maybe some Hammond case too (but than I'd have to get a nice potentiometer too, to look nicely) - it's getting expensive, with the added extras

 

[BlaBlaBla]

Usually I do not buy opamps from Chinese market. I am not trying to say that there aren't trusted sellers... I just want to say that is better to make deals with USA, Canada or Japan stores because you do not have to buy 10 opamps to get one genuine... I bought 6 opamps from China sellers (AD, Burr Brown) and 4 of them were fakes (2xAD OPA979, BB OPA627 and even cheap OPA2134). Also bought 7 opamps in Canada, UK and USA and all of them were genuine (BB OPA2111, 2xBB OPA2017, BB OPA2132, LME49720HA, 2xLM4562). Off course, price was higher but who cares when you know that IF YOUR OPAMP DIES - YOUR HEADPHONES WILL DIE WITH IT (if opamp goes off - headphones will get 5V DC voltage, and that means death after one second).
 
So, you should choose your opamp carefully.
 
 
 
Quote:

 

Let me help you, sir.
 
 

 
 

 
OPA2134.  It's a jellybean, skip it and get a pair of AD797ANZ or OPA602BP and a socketed adapter to go with them.  These will give you more significant overall improvement in sound over most others.  OPA627 is very colored, and some people like it.

 

 

[BlaBlaBla]

Quote:

Ok - thanks for the offer to help - I'll get back shortly with what I find.  I'm using highest gain setting +20db

High gain is more prone to oscillation. So if you change your opamp and use the highest gain in your LC, you should check DC offset on its headphone output. You should check DC offset with volume pot turned on to minimum, and also on to maximum. There is possibility that fast opamps like BB OPA2604, AD xxx, and especially LM xxx might start oscillating. For example AD797 is one of them. So if that happens (I tried that with AD797), your DC offset will raise from 5 mV (when volume pot is 7 o'clock) to even 60 mV (volume pot is 3 o'clock).  
 
Opamps like OPA627, OPA 2111 and especially OPA2107 are excellent choice because they are slow - and will not oscillate. Well, OPA627 is not so slow, but it can forgive mistakes in circuit topology. AD-s and LM-s will not. For something unique (blazing fast) LC is not good enough. Its topology is limited.
 
Stock OPA2134 is known as very stable opamp and you can put it everywhere (amplifiers, supplies, etc...) Because it is SLOW. So BCL (and LC) power supply and output (without feedback) are designed for slower opamps (slow if we compare them with those in medical equipment, measuring equipment, radars, sonars, TV-s...). If you trying to put fast opamp in LC without feedback, you should be careful, and always measure voltages on output. And before using expensive headphones - test 4 or 6 hours with cheap/crappy low impedance headphones.

 

[alanbeeb]

currently got pairs of 627, 637, AD797 and OPA602 all sourced from RS components in UK and waiting to roll.... but still waiting for that double adapter from China!  

 

[Monago]

deleted.

 

[alanbeeb]

Anyone know a source for the double op-amp adapter?  I've been waiting too long for the one on ebay from china.
 
 

 

[Mad Max]

Here's a couple of others that may be good.
http://www.ebay.com/itm/2x-DIP-DIP-Dual-Mono-Opamp-PCB-Adapter-OPA627BP-/220788700790?pt=LH_DefaultDomain_0&hash=item3368083676
http://www.ebay.com/itm/2x-DIP-DIP-Dual-Mono-Opamp-PCB-Adapter-OPA128SM-/120757524873?pt=LH_DefaultDomain_0&hash=item1c1db59989
http://www.ebay.com/itm/2x-Dual-Mono-Opamp-PCB-OPA2604-NE5532-LM358-OPA627-/220828096718?pt=LH_DefaultDomain_0&hash=item336a6158ce  <== I have this one.  Sturdy, well-made adapter that has lasted nearly two years of frequent use so far and still looks new.
 
You could try contacting this guy, see if he can make any, if you don't want any from China.

 

[taiyoyuden]

I recently bought one second hand from someone on this forum. I noticed the left and right channels are mixed up so I had to plug Red into White, White into Red as a temp. solution. Is there an easy way to fix this?
 
Edit: What gain setting would be best for k701?

 

[francisdemarte]

Quote:

I recently bought one second hand from someone on this forum. I noticed the left and right channels are mixed up so I had to plug Red into White, White into Red as a temp. solution. Is there an easy way to fix this?
 
Edit: What gain setting would be best for k701?

 
You'll have to open up the box and resolder the wires in the correct plug. Really easier if you know how to solder or know someone who does.
 

 

[Mad Max]

Use gain of 10 for K701.

 

[Syik]

Hello Lovely Cube owners,
 
Any idea if Lovely Cube would pair well with HD600s? 
 
Yik

 

[Mad Max]

Yes, it does.

 

[BlaBlaBla]

Quote:

I recently bought one second hand from someone on this forum. I noticed the left and right channels are mixed up so I had to plug Red into White, White into Red as a temp. solution. Is there an easy way to fix this?
 
Edit: What gain setting would be best for k701?

Cool!
 
The best gain for k701 would be to make better cooling first, and then to check DC offset - because stock BC550/560 are crap. Now I know that those PH transistors are not made by Philips and nothing but low cost fakes that like to burn very often.
 
I would like to se someone who will be able to listen to music more than 4 hours when outside temperature is >30C. "Do not drill/remove top plate, because it has to keep components warm. They sound better." - So big pile of **** I have never seen. Maybe someone likes the sound of barbecue!
 
 

 

[nsk1]

Does anyone know how much power Lovely Cube puts out at 600 Ohm?

 

[BlaBlaBla]

Quote:

Does anyone know how much power Lovely Cube puts out at 600 Ohm?

http://www.ebay.com/itm/Matrix-M-stage-Headphone-Amplifier-Amp-LATEST-VERSION-S-/330454610560?pt=LH_DefaultDomain_0&hash=item4cf0a13280#ht_6749wt_952
 
400mW into 600Ohm