[xenithon]

Has anyone perhaps compared this UD-501 to the UD-301? Used purely as a DAC, other than the filters and 384khz capability, are there any differences (functionally or sonically)?

 

[fb24601]

  Has anyone perhaps compared this UD-501 to the UD-301? Used purely as a DAC, other than the filters and 384khz capability, are there any differences (functionally or sonically)?

The major difference is in headphone amp section, UD501 seems to have dual op-amp units for each channel, while UD301 seems to have only single op-amp unit for each channel. 

 

[37mil]

The major difference is in headphone amp section, UD501 seems to have dual op-amp units for each channel, while UD301 seems to have only single op-amp unit for each channel. 

No, UD501 only has one dual op-amp per channel in the head amp. This stage immediately follows the analogue stage after the dac and is in fact one of the three output options that follow ie RCA, XLR and the head amp. This means the quality of the head amp is affected by the I/V filter op amps and output caps and then it's own op amps and output caps.

The UD301 has capacitor-less output head amp so one less thing to worry about. It also seems from the teac website the UD301 head amp has an additional op amp stage making it two op amp ics per channel. Could be the buffer for cap less output?

The website also says only two muses op amps are used whereas in the 501 four are used, two per channel for the I/V. Voltage rails are + and -12V with each channel powered by a separate transformer. The 301 only has one transformer so maybe the voltage swing is less, and only one Muses used?

I changed out all the op amps in my 501 as well as the output caps, voltage regs and power caps. The head amp can drive T1's to deafening levels at less than half way up the volume knob with its op amps changed to dexas.

 

[37mil]

I just looked up some 301 internal pics on the net and saw it does have 3 dual op amps per channel. Oddly, it seems the muses are placed at the I/V stage mixed with one 5532 followed by another 5532 filter output.

The 501 had two muses for the I/V followed by the 5532 per channel.

Maybe an expert can clarify?

 

[kawaivpc1]

How does this unit sound compared to iDSD Micro, Geek Out 1000, Oppo HA-1?

 

[apichetk]

Can the UD-501 drive Alpha Dog well?  Thanks!

 

[37mil]

Can the UD-501 drive Alpha Dog well?  Thanks!

I'm not sure about Alpha Dogs but it can drive T1s pretty damn fine. Definitely nowhere near maxing out the volume pot at listenable volumes.

I changed the op amps with dexas and it's pretty nice.

 

[apichetk]

Thanks for your response!

 

[airs]

Hi all, I received the UD-501 about a week ago, paired with the AH-501 for headphone listening and the AX-501 for speakers (Ascend Acoustics Sierra 2). At first I thought it sounded quite harsh and unengaging. The bass wasn't there, and there was too much treble emphasis..I was really disappointed but thought I'd give it some time. Over the course of the week I logged about 10 hours on it, and then yesterday I had time for an extended listening session...I'm guessing this DAC needs a bit of time to break in because I thought it sounded completely different. Laid back with incredible sound staging and detail. Also, the bass seems to have come out of hiding - deep, tight and impactful. I couldn't keep myself from toe tapping...I just wanted to listen more, and more, and more.
And so I did - for almost five hours 

 
 

 

 

[Wfojas]

  Can the UD-501 drive Alpha Dog well?  Thanks!

I've used it with an Sennheiser HD-800, AKG-K701 and Audeze LCD-X and it had more than adequate power. Hope that's of some help.

 

[Wfojas]

  How does this unit sound compared to iDSD Micro, Geek Out 1000, Oppo HA-1?

 
I've only had the iFI and Geek Out, and this sounds much less brighter that those, the detail is about the same, the mids and bass are cleaner than the iDSD Micro. I find the Geek Out to be more extended, so in some material its better, but in a lot of material its too fatigueing.

 

[apichetk]

Thanks for the comment Wfojas!

 

[mainaman]

Can you share your mods,i would like to upgrade my unit.I don't have headphones,so i don't care about its amp.I can spend up to 500 dollars if it is worth it,although i imagine that belleson regs would eat up my budget.

 

[37mil]

  Can you share your mods,i would like to upgrade my unit.I don't have headphones,so i don't care about its amp.I can spend up to 500 dollars if it is worth it,although i imagine that belleson regs would eat up my budget.

You can desolder the 6 op amps and roll as you please.  The lead spacing for the two i/v op amps aren't standard so you'll have to cut a dip socket down the middle and solder in - then place op amp in another dip socket and plug into the one you soldered into the pcb.
 
Please note, it is very difficult to remove the original op amps and the NRJ's they've used are pretty good anyway.  The two i/v ones probably not as good but easy to remove.
 
You can replace the 4 3 pin regulators.  There is one (the 5th) that does not regulate on the audio path so you don't need to change it.
 
Change the 4 big brown power supply caps.  The two green ones between them are for the headphone supply.
 
Change the nasty little green coupling caps on the audio out (4 total).
 
I used DEXA regulators with Elna on the output but it sounded terrible.  In fact, almost any cap on those outputs will colour the sound.  I asked Lars (of DEXA) and he recommended small film caps and it worked perfectly.  Sounds great.
 
These are the simplest mods that can be done.  Be warned about desoldering because it's very difficult.  Get someone to do it for you if you're not confident!
 
The regulators are expensive so maybe start with the caps first.  You'll notice an improvement changing the power caps for sure but be warned as space is tight.

 

[mainaman]

Thanks.I know that the power supply caps are KMG 35VDC 4700uF.I suppose i can change them with better electrolytics(higher voltage  rating wont be a problem,right?),but the stock ones are just 18-35mm and there is not much space between them,while the better caps like Mundorf are quite bigger,so they wont fit I read about changing the stock power supply caps to Panasonic FC or Rubycon ZL capacitors.They are very cheap and would fit,but i see voltage ratings below 35V.
 
Regarding the coupling caps,i dont know their specs yet,if they are small enough i could afford V-caps.Is it wise to spend most money on the output stage? I read about changing to Nichicon audio grade KZs,which are very cheap.
 
The DEXA regs are cheap,compared to the Bellesons,which are used in one of the upgrade services on the market.
 
Regarding the op-amps,i wont touch the Muses,maybe the 5532s.