Low output from Trends Audio UD-10

[Thunktank]

This post in a way relates to another post I made regarding desktop speakers

http://www.computeraudiophile.com/node/1313.

The following is extracted from an email I sent to the supplier of the DAC and amp I use for my desktop system;

 

Yesterday I had a Cambridge Audio Azur CD player to test so connected it to my desktop setup, the volume achieved was far higher than with the Trends Audio UD-10. I then did an additional test by connecting my Beresford DAC to the optical link on the PC and running this thru the same amp and speakers. The result was the same it would appear that the 3.5mm jack on the UD-10 has a very low level output (yes volume on PC is set to full). To gain some idea of the difference I used a sound pressure meter to check the peak levels achieved while playing the same song through the Beresford DAC and then the UD-10.

 

With the volume set halfway

Beresford > Trends TA-10 = 81dB peak

TrendsUd-10>Trends TA-10 = 65 dB peak

 

As you can see a massive difference, can you explain this; I seem to be unable to find any details about the UD-10’s 3.5mm jacks output levels on the net.

 

I have taken a look inside the UD-10and have noted that next to the 3.5mm jack are three terminal points marked“J5”, where pin 1 is square and the other two are round. I am assuming that this is a takeoff point for connecting RCA terminals and that pin one is a common ground. I am contemplating adding RCA terminals to the front of the UD-10, a far better connection than the 3.5mm adaptor supplied, though this will not solve the problem of the low level output. Any comments or suggestions are welcome.

 

Well the same applies to you guys "Any comments or suggestions are welcome".

I may just find another DAC for my desktop, as the Trends just ended up being used as my desktop DAC when it was originally purchased to be used as a media converter.

 

 

Regards Paul

 

 

[audioengr]

It's probably the USB port you are using on the computer. They are not all equal. Try another one.

 

Steve N.

Empirical Audio

 

[Thunktank]

Thanks for the prompt reply, I must admit I was skeptical about your suggestion, I would have thought that as the USB port is only providing the DAC with a digital signal that "describes volume" that each port would be identical as regards the "description" that is sent to the DAC. Considering who was suggesting this course of action I complied immediately.

My PC has three sets of USB ports 4 mounted directly on the motherboard, 2 on the front of the case running from a lead on the motherboard and a further 2 on the side of my monitor (a USB hub in effect).

I have tried one port in each location, playing the same excerpt of music and leaving the amp volume set half way, each time I got the same result a peak of 69.9dB. The same settings using the Beresford DAC with the signal provided by the PC's optical out gives me a peak of 85.6dB, as before a difference of around 16dB.

 

Whats next?

 

 

[LAMF]

The output voltage of a cdp is around 2mV, i don't know the specs of your Trents UD-10 but in my Pro-Ject USB Box i have not even 1 V, in fact it delivers only 0,775 V.

What you'll need is to advance your amp's volume control a bit. But practically all modern amps have enough gain range for that.

 

[franepici]

hi paul,

I got a TrendsAudio TA-10 amplifier, a TrendsAudio UD-10 DAC and a Styleaudio Carat UD1.

The TA-10 amplifies the PC/UD-10, and also the CD player, DVD and XBOX.

It's like you describe, for pc audio through UD-10 I have to increase the amp volume a bit more (only a bit though) than for CD, DVD etc.

However I tried to replace the UD-10 by the other DAC, the Carat, and the volume was also the same.

 

So it doesn't seem a characteristic of the sole UD-10

 

[Thunktank]

"What you'll need is to advance your amp's volume control a bit"

Turn up the volume?

If this is what your suggesting then it is not an option, this little Tripath amps THD climbs rapidly at higher volumes.

 

[franepici]

I guess he just meant the same I said in my message, increase the volume a bit

 

[Thunktank]

Nice clear answer from someone with the same kit, I would dispute your statement "only a bit though". It is generally agreed that a 6dB increase is perceived as 50% louder and 10dB is 100% louder, I am measuring a 16dB difference. It takes a doubling of power from the amp for every 3dB increase, if I assumed that with the volume dial halfway I am outputting around 5W then I would need to output 80w from the amp to hear a 16dB increase. Not possible with an amp that outputs 10w max at 8ohms. Unless someone would care to correct me. (which I’m glad to say happens all the time)

 

[franepici]

well, then maybe the difference in volume that I have out of the UD-10 is less relevant than yours.

let's say that to compensate it I have to make an increase of 1/8 turns or even less

 

[Thunktank]

It seems apparent that the output from the Trends DAC is on the low side, resulting in a lower level from the amp. I think my best course of action is to keep looking for a different DAC.

Just as a side note, I did successfully manage to modify the Trends DAC and fit RCA sockets while retaining the headphone socket. So at least I got rid of the god awful 3.5mm jack to RCA adaptor. The RCA sockets are something Trends Audio should have fitted as standard. If anyone is interested in performing this modification to the there own Trends UD10 I have kept notes and pictures, just ask.

 

Paul

 

 

[tfarney]

I don't think Trends really meant for the UD-10 to be a DAC. It seems they threw on into their transport so they could offer a passive headphone jack as a nice plus. But the one they threw in there was well, pretty good. If you don't need more the 16/44.1, I'm not sure you need a whole lot more DAC. Mine always sounded big, smooth and clean, if not quite as detailed and precise as some, even out of that godawful mini phone jack. I never had a power problemm, but I had a lot of amp at the business end of the thing...

 

Tim

 

[Thunktank]

I agree the Trends is a fine DAC at the price, perhaps "godawful mini phone jack" was a little unfair. Using the mini jack to RCA adaptor I could see the weight of the cables pulling the adaptor down at a slight angle, not a situation my OCD would allow, it was a simple task to add the RCA sockets and I enjoyed doing it. As I wish to carry on using the Trends amps I will need a DAC with a higher output if I want to gain the extra Db. So far I have 2 Airport Express's with a final target of 4 or 5 so I am going to need more DAC's anyway, an ideal opportunity to indulge my need for tinkering.

 

Paul

 

[franepici]

Well yes, I agree, the UD 10 seems not to have been primarily thought as pure DAC, but more as interface exchange out of a computer.

However their website talks explicitly also about this possibility of use.

I own one, I use it just as a DAC and I am satisfied with it. The jack out may be a bit less comfortable than a RCA out, but frankly it works fine and I do not see the reason why the sound quality should be worse than a RCA.

 

Just listening now to AC DC - Black Ice through the UD 10

 

[Thunktank]

"I do not see the reason why the sound quality should be worse than a RCA" No one ever said the sound was worse with the Minijack, it is purley a preference for a more robust connection method. Take a look on other audio forums you will see I am not the only person who has added RCA sockets to a Trends DAC.

 

The Trends designers must have had something like this modification in mind, as next to the Mini jack on the PCB are the three terminals ready for connection for analogue out.

Take a look at this image http://junkies.files.wordpress.com/2007/05/trends-ud10b.jpg you can see "J5" just next to the minijack.

Paul