[all2ofme]

Quote:

Originally Posted by TheSloth The Home/Max DAC's are a big step up from the Desktop DAC and I wouldn't recommend downgrading them. I can't guarantee that the brick is going to work properly, but then again, in terms of current draw, a Home Module + Home DAC should = Max Module + Desktop DAC in current draw. Home + Home = DAC Stage, class A output stage and 4 opamps in class A Max + Desktop = DAC Stace, class A output stage and 4 opamps in class A + 2 in class A/B. Current draw should be about the same...

Re: running a Home module and a Home DAC without a DPS.

I've been listening a lot recently with my HD650s and the Home/Home/brick through an Airport Express and have been really, really happy with a lot of what I've been listening to, but less than impressed with some stuff.

It sounds as if the very tops and bottoms are lacking on some tracks, and as if there's less of a quick attack on faster passages than I think there should be (based on hearing the same things elsewhere).

The source has been the same the whole time, so I'm not expecting it to be that that's at fault.

I'm wondering whether it's possible that the brick just isn't providing the juice the amp needs it to, so have just called Headroom to have them send out a DPS to try. It'll almost be a bummer if that improves things, since the main reason for going for the config I did was to avoid having the extra box. I'd have gone for the Max module otherwise, especially as your write-up makes it so apparent how happily it works with the Sennheisers.

Will report back. Considering returning the amp for a Maxed out version based on what happens. Eek.

Sloth: in your table of what works and doesn't without the DPS, what constitutes "working" for you?

 

[TheSloth]

Quote:

Originally Posted by all2ofme Sloth: in your table of what works and doesn't without the DPS, what constitutes "working" for you?

Working simply means that there is no current overload, and that the current draw does not exceed the maximum output capability of the brick. It has nothing to do with sonic excellence, however it must not have any audible distortion or any other obvious sign that the power supply is not completely functional.

You will of course experience an improvement with a DPS. When you say 'quick attack' that to me implies harshnses, which is not something I've noticed out of Home Modules with the brick supply. You are though indeed using it basically at its maximum output however, so you are lacking in power supply headroom for transients and peaks.

 

[all2ofme]

I don't mean that it sounds harsh - it definitely doesn't. I meant "attack" in that it sounds as if the amp doesn't have the power in reserve to deal with the transients and peaks (as you called them).

All going well the Home/Home/DPS will keep me satisfied. I'd like the niggles about a Max module to disappear since it'd be such a hassle (for me and Headroom) to send the wee beauty back and get a Max instead.

I'm hoping that some of this can be of value to the thread and that I'm not cluttering it up - it's the most useful thread I've found on Head-Fi.

 

[TheSloth]

Quote:

Originally Posted by all2ofme I don't mean that it sounds harsh - it definitely doesn't. I meant "attack" in that it sounds as if the amp doesn't have the power in reserve to deal with the transients and peaks (as you called them). All going well the Home/Home/DPS will keep me satisfied. I'd like the niggles about a Max module to disappear since it'd be such a hassle (for me and Headroom) to send the wee beauty back and get a Max instead. I'm hoping that some of this can be of value to the thread and that I'm not cluttering it up - it's the most useful thread I've found on Head-Fi.

Perhaps there is a little voltage sag on the brick? The only obvious sign of voltage sag is in the brightness of the LED. You might want to try to quickly compare the DPS and brick (not easy to do quickly!) and see if you notice any difference. The DPS has at least 5 times the output capability of the brick, I believe.

Overall though, it surprises me how good the brick is considering what it costs, and how simple it is internally. It's just a small transformer, 1 regulator and 2 or 3 capacitors. The DPS is a top notch power supply though, but look for subtle improvements that you'll notice more over time, so give it a lengthy audition - the differences will become more obvious the longer you spend with it, and in A/B'ing you might not notice as much difference as you'd like.

I suppose it also depends on your headphones, and listening level. I did those tests with the HD650's which are very easy to drive for these amps. I might try again with the K340's which is the least sensitive headphone I own (have to fip the gain switch one level higher for equivalent volume to 650's) and see if I notice any issues. That will be a while off though, as they are currently on their way to Larry at HeadPhile for his usual mods, followed by a trip to HeadRoom for FR measurements.

Btw. this certainly doesn't clutter up the thread, as your tests help to refine my assessment of the performance of the brick vs. DPS.

 

[jeffinator]

I'm thinking about finally upgrading my fairly old Cosmic... I also have an Overture/Coda combo. I'm thinking about trading in the Cosmic and selling the O/C combo to pay for the upgrade to a Desktop with Max everything.

Is this a good idea? Go ahead, encourage me to spend money!

Secondly...I do have a BS1. I saw in TheSloth's review that it can take the place of a DPS (at least temporarily). I'm just wondering how much of a difference there is...

Thanks in advance.

 

[TheSloth]

Quote:

Originally Posted by jeffinator I'm thinking about finally upgrading my fairly old Cosmic... I also have an Overture/Coda combo. I'm thinking about trading in the Cosmic and selling the O/C combo to pay for the upgrade to a Desktop with Max everything. Is this a good idea? Go ahead, encourage me to spend money! Secondly...I do have a BS1. I saw in TheSloth's review that it can take the place of a DPS (at least temporarily). I'm just wondering how much of a difference there is... Thanks in advance.

The BS1 is closer to a DPS than the brick supply in terms of quality, but it isn't quite the same thing. The BS1 certainly has the juice to power any combination of modules and DAC's in the Desktop, and will sound good, but just not quite as good as a DPS. A very small difference and as you already have a BS1 I'd stick with it for now.

Trading in the Cosmic for a 20% discount is a good idea, however I wouldn't sell the Overture stack - it's a nice piece of limited edition kit and gives you a great portable set up for those rare occasions when you might want to use it.

If you do get the Desktop, as you have a good PSU, I'm going to steer you straight for the Max/Max combo. Consider carefully the stepped attenutator - it of course gives you the best sonic performance, however you are giving up the finest control of the volume setting so it depends on your personal preference.

 

[jeffinator]

Sounds yummy!

I'm still running around with ER-4S and SH HD580s. I suppose I'll have to upgrade the Senn's as well...does it ever end?

 

[applegd]

Yesterday I spent some time to look into my MOH with 04'Premium module. Now I see what is in it, the 04' Premium module has two times HA5002 buffers, and its OPA2134s are biased into Class A. I am little bit surprised on my findings because I was told before that it only has 1 time HA5002 buffer and its op-amps are not biased into Class A.

The only difference between 04'Premium and 04'Reference is the 6 FETs after HA5002. TheSloth told me(Thanks TheSloth!), the HA5002 in 04'Premium is not in Class-A biasing because of this.

Finally I see why the sounding difference between them are not big at all. My MOH with 04'Premium is not crap yet......580smile:

 

[TheSloth]

Quote:

Originally Posted by applegd Yesterday I spent some time to look into my MOH with 04'Premium module. Now I see what is in it, the 04' Premium module has two times HA5002 buffers, and its OPA2134s are biased into Class A. I am little bit surprised on my findings because I was told before that it only has 1 time HA5002 buffer and its op-amps are not biased into Class A. The difference between 04'Premium and 04'Reference is the ???s after HA5002. TheSloth told me(Thanks TheSloth!), the HA5002 in 04'Premium is not in Class-A biasing because of this. Finally I see why the sounding difference between them are not big at all. My MOH with 04'Premium is not crap yet......580smile:

I see from another thread that you have a Micro with the '06 Desktop Module as well. Could you offer any comparisons in sound, notwithstanding the much improved PSU in your MOH?

Regarding the DPS, I have experimented with positioning and ground settings and find that it should be placed as far away from possible from the Desktop unit itself, and that the ground lift swich is very helpful in my NY apartment with very questionable electrical grounding. Stereophile measured some interference from the DPS when the units were stacked, and my ears tell me it's a hair cleaner with some distance between the two - props to HeadRoom for including a decent length cable.

 

[applegd]

Quote:

Originally Posted by TheSloth I see from another thread that you have a Micro with the '06 Desktop Module as well. Could you offer any comparisons in sound, notwithstanding the much improved PSU in your MOH?

Just got time to compare my MicroAMP(with '06 Desktop Module) with my 04' MOH(with '04 Premium Module). Overall the sounding of MicroAMP is good, sometime I can feel it is trying very hard to sound good, but it does not have the relaxing/easy signal control capability of MOH. I think the Dual toroidal PSU contributes a lot here. The other factor is 2134 in MicroAMP is not class A biased.

 

[Bob A (SD)]

I came across this old thread and noted that the original modules, which are not upgradeable, aren't mentioned.

Stereophile reviewed the first Headroom model in their January 1994 issue (delivered several weeks before Christmas). I bought a Headroom Supreme along with Sennheiser HD580IIs from the Bozeman gang in late December of 1993. The three flavors were Standard, Premium, and Supreme. Prices, if memory serves, were $199, $299, and $399. Mine was the $399 Supreme which featured a Burr-Brown OPA2604AV op-amp, Caddock 132 metalfilm resistors, and Mallory SKX poly caps. The module was cast in some sort of sealing resin obviating any later modifications. Pin outs for the module were not similar to later versions again killing any upgradeability. Mine was also optimized for the HD580s being set at 20kOhms and 6800pF. Output was a generous 400mW.

Able to run on AA batteries, this bad boy weighed 1 pound empty and added another 4 ounces when loaded. Size was big by today's portable amp standards at 6.2" x 5.25" x 1.1". Later a better PSU was offered to replace the wall-wart for home useage.

Mine is still humming along and, while definitely not even close to state-of-the-art, it continues to provide satisfying synergy with those same Senn cans bought back in '93

 

[TheSloth]

Quote:

Originally Posted by Bob A (SD) I came across this old thread and noted that the original modules, which are not upgradeable, aren't mentioned. Stereophile reviewed the first Headroom model in their January 1994 issue (delivered several weeks before Christmas). I bought a Headroom Supreme along with Sennheiser HD580IIs from the Bozeman gang in late December of 1993. The three flavors were Standard, Premium, and Supreme. Prices, if memory serves, were $199, $299, and $399. Mine was the $399 Supreme which featured a Burr-Brown OPA2604AV op-amp, Caddock 132 metalfilm resistors, and Mallory SKX poly caps. The module was cast in some sort of sealing resin obviating any later modifications. Pin outs for the module were not similar to later versions again killing any upgradeability. Mine was also optimized for the HD580s being set at 20kOhms and 6800pF. Output was a generous 400mW. Able to run on AA batteries, this bad boy weighed 1 pound empty and added another 4 ounces when loaded. Size was big by today's portable amp standards at 6.2" x 5.25" x 1.1". Later a better PSU was offered to replace the wall-wart for home useage. Mine is still humming along and, while definitely not even close to state-of-the-art, it continues to provide satisfying synergy with those same Senn cans bought back in '93

Thanks for that blast from the past! Yes, those original modules were potted so it's impossible to see what's going on underneath (though I believe Jamey had some success getting the epoxy off some of the modules they had lying around).

Was that a 12 pin configuration?

 

[Jamey Warren]

I do have a couple of old modules around but I haven't had a chance to put on my reverse engineering hat yet.

 

[Bob A (SD)]

Quote:

Originally Posted by TheSloth Thanks for that blast from the past! Yes, those original modules were potted so it's impossible to see what's going on underneath (though I believe Jamey had some success getting the epoxy off some of the modules they had lying around). Was that a 12 pin configuration?

Quote:

Originally Posted by jamey I do have a couple of old modules around but I haven't had a chance to put on my reverse engineering hat yet.

Honestly, it's been so long since I peaked under the hood that I'm not sure exactly how many pins there are. I did inquire a couple years ago about exactly what Jamey is suggesting but I was told no joy and instead was offered a trade-in discount. These days it is mated to my bedroom system's Nakamichi TA-3A Stasis receiver and rarely sees any travel time.

 

[headfone]

Quote:

Originally Posted by TheSloth /img/forum/go_quote.gif Sonic impressions of the pre '04 modules. Fundamentally, the design dates back to 1997 or even earlier, however this particular version was released I believe in 2002, and discontinued in August 2004.

In Jan 1997, I had Headroom install the Premium Module into a 1995-built Little. After 10 years, I finally peaked under the hood. All the module components had their labels covered with black ink, as I also noticed in some of your photos. A few Q-tips, 99% isopropyl alchohol, and a solid 10 minutes "cleaning (or more like scrubbing!) time" allows one a better look:

Also, for those curious, here's a peak under the hood of a 1997-built More Power Supply unit.