[Banfi T.]

Quote:

Originally Posted by 00940 Oh, it was mostly rhetoretical. They were used massively for example in the PassLabs D1 DAC, to regulate the voltage for the analog stage. It was a <5000$ unit. Chances are that if you have a cdp under 1K, the dac is getting its voltage from a LM7805. The Benchmark DAC1 is using LM78**/79** regulators for its opamps too (see the old thread about that)

Huhh...kinda scarry to hear it. However, they could be fine as first stage regulators after the C-R filtering. Then something with a lower noise and smaller output resistance at a wider bandwitdth....

Ps.: some opamps are tricky in this regard. E.g. the AD797 has more than 100dB PSU noise rejection on its own. It works just fine with a simple C-R-C filter. Others have less then 50dB rejection.

 

[sean-xenos]

Well, bad news on the TW-J1 if there are such big parts tolerances or even variations in design (just whatever parts seem to be at hand or in stock).

On the other hand I finally tested the TW-J1 with my Sennheiser HD650 and the combo sounds good

There's lots of deep bass, very natural mids and slightly rolled off highs (but that's what you have to expect from a HD650 anyway as it's a rather dark sounding headphone, certainly not as bright as a Grado). I found out that I can correct the sound signature by using brighter sounding interconnects like the Fast Audio Starline for example.

Maybe it's the right time to open this amp now and have a closer look a the parts used in my amp. I'll keep in contact with Mike, Borat and tiberian.

 

[oneeyedhobbit]

Quote:

Originally Posted by sean-xenos Maybe it's the right time to open this amp now and have a closer look a the parts used in my amp. I'll keep in contact with Mike, Borat and tiberian.

I wouldn't mind being kept in on the loop either (I also own TW-J1). Meanwhile, I've contacted the people I ordered my amp from (yes, the infamous knoxed.com group, who have been very kind to me)--I asked them some of the questions raised in this thread. They told me they are looking into it, and a statement from the designer of the amp is pending.

 

[sean-xenos]

Quote:

Originally Posted by oneeyedhobbit I wouldn't mind being kept in on the loop either (I also own TW-J1). Meanwhile, I've contacted the people I ordered my amp from (yes, the infamous knoxed.com group, who have been very kind to me)--I asked them some of the questions raised in this thread. They told me they are looking into it, and a statement from the designer of the amp is pending.

Hi oneeyedhobbit,
a hearty welcome to TW-J1 home-mechanics crew

.

I wouldn't expect anything from "knoxed-com", they did not answer my questions, they claim not to be a legal entity and try to play every trick to bypass legislation on customer rights

The designer of the amp has not answered my questions either (email was sent 14 days ago to qingyilun@126.com, that's the email address given in the manual).

 

[Borat]

Thanks for your efforts hobbit. Especially since the few of us in the US who bought the J1 from other dealers in Hong Kong essentially have no recourse for returns/warranty on these amps. I look forward to hearing a response, hopefully from The Wu Gang Man

.

sean-xenos, if you decide to open your amp, could you take pictures of the inside of your J1 and post them? I would appreciate it for comparisons. Thanks.

 

[sean-xenos]

Quote:

Originally Posted by Borat sean-xenos, if you decide to open your amp, could you take pictures of the inside of your J1 and post them? I would appreciate it for comparisons. Thanks.

Hi Borat,

my amp looks exactly like this
http://www.knoxed.com/ebay/DSC00727.jpg

though I did not buy it at "knoxed-com"

 

[Fidelity]

Looks like you're in luck judging by the photo.

 

[Borat]

Thank you sean for the response.

Fidelity, what can you infer from that picture? I don't know much about amp parts, but visually, sean's and PinkFloyd's J1's use different brand capacitors in most places.

 

[Fidelity]

If I'm not mistaken, the caps used have better/closer tolerance levels than the ones shown on the "other version/s", one example is the 7 or so red looking caps on Sean's unit while the other units seem to have lower grade white caps in place.

My amp internally looks identical to the one in Sean's photo.

 

[Gabe Logan]

I would like to post a picture of mine but wouldn't taking off the sticker on the back void the warranty?Come to think of it, i dont know if it even has a warranty.

 

[Grif]

Mine looks the same as Sean's and Fidelity's and sounds superb....but if those pics posted buy Borat are of Pinkfloyds amp then he has alot of different caps in his, but it still sounds excellent???

 

[Fidelity]

Floyds amp seems to be the exception so I think (like his mate said) he was lucky that his amp sounded good.

If your amp looks internally identical to Sean's then the chances are it should sound fine due to (it appears to be) tighter tolerance caps/parts.

 

[Hornet600]

Quote:

Originally Posted by Fidelity LOL, explains why I received an email from a friend (another a/v nut) last week full of F'ing and BS about my head amp recommendation... Check the link above which has a few photo's of the amps internals, you will see that there are infact two version of the amp, one that is made to original spec, and the other that seems to have been fitted with cheaper/inferior parts in place. Do G&W allow different/inferior parts into their other equipments that deviates from the original designs?

As I understand, most friends here who have J1 gave good comments to it but their "friends" did not think so. In addition, what we can see from the pictures are different parts but, to be honest, as a headfi fan, I really can't tell from the pictures which are better parts and which inferior. Has anyone noticed that most of Arcam & Cambridge audio products say "Designed in the UK" but not "Made in the UK" on the back now? The reason is that they are made in China! You think the OEM factories will use the same parts for production? And won't Arcam & Cambridge care about their reputation if the quality made in China is inferior?

Headfi fans in China also have different comments on J1 because there is not necessarily one agreed taste and people have different systems --- I think it is very normal that people having differnet tastes give different words to a same product.

Chinese hifi products are known for their unbelievable value for money. For a product that gives the same sound, I have to pay double or even more than tripple in the UK. For a MF X-Can V3, I paid GBP250 in the UK, but in China I can get it for only GBP150, and HP200/T2.6F/AM650 are much better amps and they are priced at lower levels. We have a lot of internal pictures of J1 here, can any body pls show some internal pictures of Creek OBH21SE for GBP250 and compare them?

Those friends who have J1 at hand, you like it because you think it sounds good or you don't like it because other people don't think so?

I know many people won't agree with me and I apologize if I made any one unhappy by saying so. I am not saying this is also true here --- but in China, many people think imported goods are better than those made in China because they pay a lot more money for imported goods --- I believed so when I bought my MF X-Can V3 in the UK, however, after I came back to China with it, I found myself completely wrong!

Cheers!

Eric

 

[electra]

I picked up the G&W t2.6f 110v version yesterday. Build quality is excellent. It has better detail compare to the Earmax Pro. Only spend a couple of hours listen to it, so I can't really give too many comments.

 

[sean-xenos]

Quote:

Originally Posted by PinkFloyd "If all of the components were carefully matched and selected to give mimimum output offset at the same time as lowest crossover distortion then I believe that the amp could sound good. Obviously component selection and matching are out of the question for such a low cost amp. The amp has no temperature compensation so that as the output devices warm up the quiescent current will increase away from the optimum value for minimum distortion ( in the unlikely event it was at this value to begin with ). This will happen gradually over the space of 30 to 60 minutes so you won't be too aware of it. Mike.

Thanks to Mike's wonderful instructions I was able to meter the DC offset of my TW-J1.

At the beginning it was 0.00 mV on the left and 0.03 mV on the right channel, so the amp was probably adjusted "cold" by the manufacturer

After about one hour the DC offset was stable at 2.6 mV left and 2.4mV right channel. Mike told me that this is a good value, so there is not really a big problem with the amp warming up. I don't think that warming up will change the sound

.
I adjusted the DC offset to 0.00mV and it almost stayed at this value for the rest of the day, the metering was always between +/- 0.30 mV and this is next to nothing.

So the lucky guys who got hold on a good sample of the TW-J1 shouldn't worry.

Still, as Mike already pointed out, I can't recommend to buy this amp in general due to the sample variations and big tolerances of the capacitors used in about half of these amps. You may not be as lucky as I was, so it's too much of a risk!