HeadRoom Amp: Which one?!
Sep 1, 2007 at 6:56 PM Post #61 of 87
Back with my report on the wall-wart ("WW" for short) as alternative to the DPS for the Max+Max Desktop. ("Wall-wart" is actually a misnomer. This is a brick. But I adhere to HeadRoom's terminology.)

In order to avoid any burn-in issues, I used the WW that's been powering my Micro amp, not the one that's been sitting in a box since I got my Desktop. This is the same APS48-ER-125.

I thought I'd let the DT run on the WW for a while before listening critically. So, while I had a meal, I played a DVD and listened casually on the Denon D5000, the digital signal going through the Max DAC. This was an episode of the TV series NCIS. (BTW, I can't recommend this series. It's ordinary TV fare with hardly any redeeming qualities. I got it as a bargain at a second-hand store for the widescreen presentation. However, my expectation for these things is so low (as 99% of TV fare is dismal) that I must confess it actually grew on me somewhat. I like the picture, the rich production and the dynamic soundtrack. So, it's become a minor headphone accessory for me. [Hard-core audiophiles know what I mean!
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] If it weren't for the excellent Pauley Perrette and David McCallum, there wouldn't be any actors in it. But...yes, I digress!) According to my plan, there wouldn't be any mention of NCIS in this report. I was just warming up for the real job of listening through episodes of The Sopranos and MI-5, for starters. If the WW cleared the DVD hurdle, it would then be time for those 24-bit Rudy Van Gelder recordings of the Hammond B-3 guys, Jimmy McGriff and Joey and Papa John DeFrancesco to begin with, with Dr. Lonnie Smith waiting in the wings for some more organ mayhem. Then, it would be the time for big bands, etc., etc. At that point, the DX1000 would have been called in for reassurance, of course.

All the trouble I had in mind proved unnecessary, however, I'm sorry to say. I knew there were things I'd notice instantly: noise, compressed dynamics, flabby bass. If the WW showed that kind of misbehavior, I'd pull the plug on the experiment immediately. It didn't. I was pleasantly surprised. There was the promise of a real fight. I got all hopeful. But, half-way into the NCIS episode, I was sure there was something bothering me. The NCIS dialogue is always mildly sibilant on the D5000 – just mildly so. (It's the recording; the phones just mercilessly expose the flaw.) But there was nothing mild about the sibilance I was hearing. Time to replace the WW with the DPS. The sibilance was much reduced; it was mild again. I switched back and forth a couple more times. Nothing subtle about it: the WW gave me more sibilance than I deserved. So, there it was: a clear difference. But then, as I made sure the difference was real, something else emerged. This is subtler and harder to describe. As one of the characters quickly moved from center to left, the sound of her voice collapsed more readily than it should into the left cup. The DPS showed a more natural transition, with the spatial cues more naturally portrayed. There was no doubt in my mind: the WW affected imaging adversely – even if only minutely so. And there is more. As I replayed a long passage to make sure there really was that slight imaging problem, it became clear that the decay following bass slam was shorter with the WW. But this was even subtler than the other effects. Still, for one who values bass as much as I do, this was another major setback.

That's where I pulled the plug on the WW. In view of the fact that time is in very short supply for the hobby, I promised myself I'd stop the test as soon as a single noticeable difference came up. I didn't set out to try and find every detectable difference. So, I was done with my test.

As much as I hate to admit it, the "refinement" thing reared its ugly head and proved the DPS superior to the WW to my ears. Is it $399-superior? All I can say is: If I didn't have these brutally revealing phones, I'd probably live happily with WW as power supply. That's the good news: Even for top-tier phones, the WW can be used in an emergency without causing any major teeth-grinding. Otherwise...

Now, there's major rooting for the Astrodyne here!
 
Sep 2, 2007 at 9:50 AM Post #62 of 87
Quote:

Originally Posted by Soundinista /img/forum/go_quote.gif

Now, there's major rooting for the Astrodyne here!



Thank you for that experiment, ultimately this is what's needed to clear up the SQ issue between these power supplys. Considering that the WW has an output of 240mA and the Astrodyne outputs 1.35A I would like this experiment to be remodeled utilizing the Astrodyne however. What makes me so confident about the Astrodynes driving ability is the fact that it's provided as standard with the Desktop Balanced. If you visit Headrooms page on this amp and lookup the Internal image, you'll see that in a balanced configuration, there are 4 Modules for the Home amp not 2 like in the DT version(In line with Balanced Topology). Couple this already spike in capacity with the Home Dac and the power demands are increased dramatically. I am positively secure this is why Headroom do not post specs combined with no printed data as per included manual upon purchase. Why buy DPS when the Astro variant would satisfy.
I Have been in contact with forum Member 'TheSloth' regards this topic and his reply on the Current draw issue was "From the technical information that I have, the Max + Max consumes about 250mA per rail. That's about 1/6 of the Astrodyne's output capability" Which would explain the less than spectacular result you achieved in your experiment(double current Draw total needed) with the WW. Now insert the Astrodyne and all should be well.
If only we could get one of these Astros out to you to complete and confirm the combined conclusion here.
 
Sep 2, 2007 at 11:03 PM Post #63 of 87
Quote:

Originally Posted by Cecala /img/forum/go_quote.gif
Considering that the WW has an output of 240mA and the Astrodyne outputs 1.35A


The good power supply needs to pump out enough quantity of clean current, but don't forget it need to be fast enough to provide the needed current too....
 
Sep 3, 2007 at 10:03 AM Post #64 of 87
Feifan, dear boy, it is now up to you to further our cause by hopefully performing the test we now need to finally settle this. It is up to you to compare the Astrodyne and DPS running the Max+Max DT Desktop. I have re-read Max Dubios review on this matter and see from images(Headroom) that the 'refinement' aspect is due to two things. Firstly the size of the smoothing caps on the Brick and DPS. Secondly the Current capacity from both setups and is ample form the Astrodyne thus power delivery is no longer a concern. So ultimately it comes down to the quality of the Switching type Astrodyne. Can it be compared to the DPS for SQ?
 
Sep 29, 2007 at 3:39 AM Post #65 of 87
Hi everyone. This thread has been a bit quiet. Perhaps my news will liven it up a little. I finally made a decision and did the deed. Today, I placed an order for a Desktop amp with Max amp and dac modules, stepped attenuator and DPS. HD650's are also coming. So now, it's down to waiting. I'm keeping my fingers crossed to have it all within two weeks. It's a good thing the exchange rate is highly favourable at the moment!
 
Oct 6, 2007 at 1:04 PM Post #68 of 87
Quote:

Originally Posted by bradman /img/forum/go_quote.gif
Hi everyone. This thread has been a bit quiet. Perhaps my news will liven it up a little. I finally made a decision and did the deed. Today, I placed an order for a Desktop amp with Max amp and dac modules, stepped attenuator and DPS. HD650's are also coming. So now, it's down to waiting. I'm keeping my fingers crossed to have it all within two weeks. It's a good thing the exchange rate is highly favourable at the moment!


Quiet thread?! No, no, that ain't right! We must do something about it!
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Congrats, Bradman! Let us have your report when it arrives, will you?

Cheers,
 
Oct 8, 2007 at 2:03 PM Post #69 of 87
I am trying to decide whether to get the Stepped Attenuator or not. It does scare me to think about not getting the right sound level!!!
Some people here have opted for the Stepped Attenuator as an option, how has your experience been with sound level adjustment and how firm or damp is the clicking action?
 
Oct 8, 2007 at 5:07 PM Post #70 of 87
The Stepped Attenuator is good, it has a firm and positive clicking action. Combined with the gain switch it is very easy to set the desired volume with different sources and headphones.
 
Oct 8, 2007 at 8:39 PM Post #71 of 87
Quote:

Originally Posted by AlanL /img/forum/go_quote.gif
The Stepped Attenuator is good, it has a firm and positive clicking action. Combined with the gain switch it is very easy to set the desired volume with different sources and headphones.


Exactly! It took me a while to get used to it, as it feels much tighter than I expected. But I don't regret having it at all.
 
Oct 11, 2007 at 3:33 PM Post #72 of 87
What is heard when changing between steps from the headphones, does the sound quickly turn from on to off back to on?
Also going by my deduction, the displacements on the HR total 24 steps. Now the gain switch has 3 positions, so 3x24=72 actions. This would in theory give the ability to fine tune the sound.
 
Oct 12, 2007 at 7:03 PM Post #74 of 87
Hi folks. My order has finally been shipped! Audio nervana approaches. Fingers crossed for Tuesday next week. However, I have a question. Could someone who has the DPS tell me does it come with a US-terminated power cord or do you connect to the wall outlet via an IEC cable like the Astrodyne? I've looked through the downloadable manuals and it's just not clear to me. I need to know if I have to go out and pick up a computer power (IEC) cable or if I just need an adapter to convert the US pin configuration to the local one used here. It would be a shame for it to arrive and find that I'm missing the means to connect it to the mains.

Thanks.
 

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