[edulov]

Too subjective.
Due to the valve types used in LD3, it is intended to sound drier (analytical) which more people qualify as better HiFi. People mistake forced lack of harmonics with true HiFi.
Mine Nob is not either noisy, either grainy or softy + HQ audio and USB cables. Also I never considered 712 since they fail in high treble. Considering their cost it becomes a deadly flaw.
So I just won't consider this mentions as relevant. (no abuse, just tech specs).

 

[henkeman]

  Too subjective.
Due to the valve types used in LD3, it is intended to sound drier (analytical) which more people qualify as better HiFi. People mistake forced lack of harmonics with true HiFi.
Mine Nob is not either noisy, either grainy or softy + HQ audio and USB cables. Also I never considered 712 since they fail in high treble. Considering their cost it becomes a deadly flaw.
So I just won't consider this mentions as relevant. (no abuse, just tech specs).

It might come down to what one prefers and hears... I only gave my opinions based on my own hearing observations, preferences and knowledge at the given moment. Yes the harmonics in the nobsound are really good, but I  dont think they mean everthing in music. There is allways an element of balance that is needed.
 
To me the LD3 sounds more realistic and true to real sound as heard i real life performances etc. But please enlighten me to what "true HiFi" is because I really dont know what else it could be.
 
I really think there is something special with the triode strapped pentode and I happily will use it again. Maybe I will be disenchanted by the LD3 and find that I like the nobsound more. I dont know, but right now Im able to enjoy music more with the LD3.
 
In the beginning I was disappointed with the LD3 because the thin analytical sound. But with higher gain and headphones that are fuller by nature they are really sublime. I will replace the Voshods with a more tubey sounding tubes.
 
I only heard the noise/grainyness in direct comparison with the LD3. If I hadnt done the comparison I would have thought it was in the recording or something further upstreams. I only have the stock op-amps in the nobsound.
 
I dont have any high treble problem with my k712, there might be a spike somewhere but nothing I could discern with my hearing. I think there might be different kinds of k712 or it is all subjective based on ones hearing. Some say they are bass weak/strong, mine are bass strong, some say they are dry, mine are not dry at all. They seem to pick up harmonics for good and bad. Some say they have treble problems mine dont. Some say they are thin or full, mine are full. I only gave $200 for my pair compared to the $220 i gave for mi HD600 which in my opinion are inferior in every way except balance. Modded my K712 by placing a pair of Fidelio X2 earpads on top of the stock ones an that brought balance so now I will sell the HD600s, 

 

[DJ The Rocket]

Rolling tubes.
Before anything else please understand that 6ж9п valve have many direct analogues and highly compatible ones also. Due to fabrication processes and materials they are not identical, so the devil hides in details. But first of all here is a list of all references, especially if you will look for them at eBay:
6ж9п, 6j9p, 6g9p, 6zh9p, 6ж9п-Е, 6j9p-e, 6g9p-e, 6zh9p-e, [COLOR=00000A]5A/170K, 6688, 6688A, CV3998, CV6189,[/COLOR][COLOR=00000A]E180F[/COLOR]
[COLOR=00000A]Adding suffix letter usually means long life version of tube, also with refined specs.[/COLOR]
[COLOR=00000A]Since I wanted to keep “playing” with this amp for some time, I tried some, definitely good options, but will continue testing[/COLOR] [COLOR=00000A]after finding valves at reasonable prices.[/COLOR]

[COLOR=00000A]At the moment I checked just 3 of them, but all - very good ones:[/COLOR]
[COLOR=00000A]- General Electric 6688, US[/COLOR]
- RCA 6688A (made by Mullard)
- Amperex JEP-6688, CША

If you want studio-type sound you need GE. Detalization, resolution, separation of instruments, soundstage – exceptional. BUT! They do have bass extension w/o good punch and density. It does not mean that you will get problems with lows, since they are fully controlled. Just not too much. So this valve is not for bass heads.
RCA and Amperex JEP are very similar. Just a little bit less of “open air” but much more prominent lows. Overall control is equal, punch and density. With one small detail – Amperex offers even bass density up to the lowest extension, while RCA offers less “body” at low-low bass. But once again, it will be important only for a hardcore bass head. Also RCA has lesser depth (not width) of soundstage, but you will need very good open cans to capture that. That’s why I am using Amperex JEP.
A bit later I’ll try “normal” Amperex, comparing with JEP version and RCA’s once again.

I'm looking at a pair of GE 6688 ($14/pair) and regular Amprex 6688 ($22). Can you (or anybody) tell me if you feel the difference in quality is enough to be worth $8?

 

[edulov]

About GE and Amperex/RCA/Mullard
 
GE offers more analytical sound w/o emphasis in lows and not so extended in lows.
Since one part of the music, I'm listening "kicks" and I prefer open/semi-open cans which slightly lack bass, I keep GE's for special occasions.
But if you prefer closed hp's, especially bass focused, GE's might offer you balance.

 

[TheBIGKill1998]

Heya guys, first of all, im new and this is my first post. And this is just meant to be a little reply containing my current experience with this amp. 
 
To make 1 thing clear at the beginning, it is not a "real" hybrid tube amp, since the tubes are not directly used for pre-aplification, they are simply used as input buffers. 
(still it is a great little amp tho, with a nice charme of tube flavour in the sound) 
 
I use this amp at my PC with the Behringer U-Control UCA222 USB Audio Interface as DAC. 
In my setup this little amp sounds pretty good for what it did cost.
 
Currently im using russian 6j9p tubes, which sound pretty awesome, whilst being relatively cheap (i got 10 of those for 20 euros including shipping costs).
I exchanged the op amps of it with LM4562NA ICs. I highly recommend those since they deliver more details than the stock ones. 
 
Before i used Tesla E180F tubes, which i personally did not like much.
 
 
 
To sum this all up, here's a little list of things i recommend when you're using this amp:
 
- Exchange the opamps (maybe with the ones i named earlier)
- Use other tubes (i recommend the russian 6J9P ones)
- Use a DAC
- remove the blue LEDs (i just think it looks sooooo much better without them) 
 
- if you decide to change the opamps, dont use/buy the OPA2604 ones.... i tried them.... and they seem to NOT match the electrical specs of the amp. I had constant weird noises coming out of my headphones, when i tried them out.

 

[henkeman]

Are these the 6J9P or the 6J9P-E you are using? How would you say they compare to the Teslas?
 
Popped in my Valvos again and concluded I liked them more than the Teslas.

 

[TheBIGKill1998]

  Are these the 6J9P or the 6J9P-E you are using? How would you say they compare to the Teslas?
 
Popped in my Valvos again and concluded I liked them more than the Teslas.

Hello,
 
I'm using the normal 6J9P Tubes and they sound pretty great. But the only difference between 6J9P and 6J9P - E Tubes, is that the 6J9P - E ones have a longer lifespan and are better built.
 
Well, compared to the Teslas i would say, that the Teslas seem to be kinda muddy and with less Detail. I would say that the 6J9P Tubes sound pretty analytical. They have plenty Detail, whilst keeping up the typical tube warmth.
 
But do not only focus on Tube Rolling. Rolling the Opamps changes the sound by quite a lot and can also improve it by far.

 

[DangerClose]

 
I'm using the normal 6J9P Tubes and they sound pretty great. But the only difference between 6J9P and 6J9P - E Tubes, is that the 6J9P - E ones have a longer lifespan and are better built.

 
Have you tried both kinds?  I would say there's a clear difference.  Though one of my sets had more hours on them than the other, so that could have been a factor.  Before trying them, I had also read at least a couple people around the internet say they sound different.
 
There's different 6j9p too.  I have some taller ones, and some shorter ones.  All labeled 6j9p (or foreign language equivalent).  Those sound different too, though, again, some had more hours than the others.

 

[TheBIGKill1998]

   
Have you tried both kinds?  I would say there's a clear difference.  Though one of my sets had more hours on them than the other, so that could have been a factor.  Before trying them, I had also read at least a couple people around the internet say they sound different.
 
There's different 6j9p too.  I have some taller ones, and some shorter ones.  All labeled 6j9p (or foreign language equivalent).  Those sound different too, though, again, some had more hours than the others.

No i have not tried both types. I am just saying what i know from their Descriptions. 
 
The taller ones are a different type then. 
But yeah, since the 6J9P-E Tubes are built differently (in general better built with a longer life span) it sure is possible that they sound different.
I just did not know about that for sure.
 
Which ones sound better in your opinion?
 
If they really sound different, i really have to try them out!

 

[Brian Coffey]

What Op Amps seem to work best with this amp so. And is it a single or a dual?

 

[TheBIGKill1998]

  What Op Amps seem to work best with this amp so. And is it a single or a dual?

It uses 2 ne5532 dual op amps. I exchanged them with the lm4562 op amps. 
Just looking at the electronic specs they are almost a perfect match.
I think that they outperform the stock ones (ne5532) in each category.

 

[Brian Coffey]

  It uses 2 ne5532 dual op amps. I exchanged them with the lm4562 op amps. 
Just looking at the electronic specs they are almost a perfect match.
I think that they outperform the stock ones (ne5532) in each category.

Thank You! May order a couple this weekend.

 

[TheBIGKill1998]

  Thank You! May order a couple this weekend.

You are welcome! 

 

[fjhuerta]

I was wondering if anyone has noise issues with this amp. I just got mine and it has this noise. It's not  a 60 Hz hum, it's like surface noise on vinyl. It's very noticeable. It goes out whenever I take out the tubes. Any ideas will be greatly appreciated!

 

[MisterMudd]

I was wondering if anyone has noise issues with this amp. I just got mine and it has this noise. It's not  a 60 Hz hum, it's like surface noise on vinyl. It's very noticeable. It goes out whenever I take out the tubes. Any ideas will be greatly appreciated!

Had mine 8 months now, and though the stock tubes were good I replaced them quickly. Try some other inexpensive tubes before sending the amp back to replace or refund. When it works, it works very well and sounds great. Got my replacement tubes on eBay.