[Anaxilus]

Quote:

 
Here is a comparative guide to assist your understanding of HD650's at their max:
 
BASS: The rumbling bass should call to mind an earth trembling buffalo stampede
MIDS: The flawlessly natural mids call to mind the luscious bosom of Gaia, our Earth Mother
TREBLE: And here the incorruptible treble seduces like Homer's sirens, transforming reality and reason

I don't know if you've figured out your target audience here yet, lol.  I mean geez man....
 
Btw, is Gaia a C cup or Double D?

 

[qusp]

Quote:

Nothing is "buggered-up", what is wrong here is that this linear half wave power supply has gnat balls when HD650's require swinging truck nuts to sound their best. Sure some of you think it sounds clean and clear or whatever, but I feel you're not true connoisseurs of HD650 sound, if you were you'd know that this amp rates firmly in the nice-try-but-no-cigar category when driving HD650's. Unfortunately the amp simply won't sustain what is necessary to max out the HD650's.
 
Here is a comparative guide to assist your understanding of HD650's at their max:
 
BASS: The rumbling bass should call to mind an earth trembling buffalo stampede
MIDS: The flawlessly natural mids call to mind the luscious bosom of Gaia, our Earth Mother
TREBLE: And here the incorruptible treble seduces like Homer's sirens, transforming reality and reason
 
 
 
 

nope, half baked sennheiser cliches aside (happy owner of hd600 here), if the regulator is overheating as you say and this hasnt been picked up in sims, by the test build team, or by the myriad of other people including first time builders that have built the amp so far; you most certainly HAVE buggered something up
 
oh and you seem to have a misconception on how much voltage 300 ohms headphones need. in fact, given the amp has enough swing(which it does), the hd650 will be more readily driven than something of 16-28 ohms. its a pretty easy load actually for anything that has more than a single 9v battery and is handily done with just over unity balanced from my sabre. (4vrms, but i dont get close to maxing that out) sure those mathematically inclined will spout some waffle about needing 7-8v to cope with peaks equivalent to a classical concert, but only an idiot stands in the front row there without hearing protection

 

[Paul Blythe]

IIRC from his blog and if your upto trusting nwavguy's measurments... 5.7V

 

[khaos974]

Quote:

IIRC from his blog and if your upto trusting nwavguy's measurments... 5.7V

Actually 6.8V on AC into Zload > 80 ohms.
 
 

 

[Willakan]

@Cheapskate
 
Wait a second, don't the regulators have thermal protection? I'm pretty sure they shut off when they get too hot rather than just let themselves burn out.
 
EDIT: Yup, they have thermal overload protection, in big letters on the first page of the datasheet. How on earth did you manage to fry them? 

 

[Paul Blythe]

I now can't find the post I was refering to... but iirc nwavguy built-pionted about the the HD 650's being happy with 2vrms with 5.7v peak, or somthing like that. If I can find the reference again I'll quote it, otherwise just ingnore what I said
 
Quote:

Actually 6.8V on AC into Zload > 80 ohms.
 
 

 
 

 

[mikeaj]

Quote:

I now can't find the post I was refering to... but iirc nwavguy built-pionted about the the HD 650's being happy with 2vrms with 5.7v peak, or somthing like that. If I can find the reference again I'll quote it, otherwise just ingnore what I said

A 2V rms sine wave is 5.7V from peak to peak (top to bottom).  The conversion factor is 2 * sqrt(2) for sine waves.  O2 can do a 6.8V rms sine wave into 300 ohms, so up to about 19V peak to peak, so not even close.
 
If the regs are legitimately too hot, then you could also try running on batteries, since that should have enough power as well, given nothing downstream in the circuit is awry.

 

[khaos974]

Quote:

I now can't find the post I was refering to... but iirc nwavguy built-pionted about the the HD 650's being happy with 2vrms with 5.7v peak, or somthing like that. If I can find the reference again I'll quote it, otherwise just ingnore what I said
 
Quote:

Actually 6.8V on AC into Zload > 80 ohms.

Ah... we were talking about different things, I was referring to the max voltage swing of the O2 which is 6.8 Vrms, you were referring to the voltage needed to achieve 110 dB peaks for the HD600, which is about 5.7 Vp-p.
 
 

 

[estreeter]

OK, fwiw, I'm prepared to take the above warning from cheapskateaudio onboard - just use batteries when I'm actually using the amp. Fortunately, I dont have demanding cans, but I do have a powerful source if some of the hoo-ha about the MSII is anything to go by. Even if the 02 does die within 6 months, it will be an education - I doubt that there are very many professional designs that adhere strictly to the wire-with-gain edict - my personal belief is that many Head-Fiers want something warm and euphonic. Accuracy ? Sure, but not if it gets in the way of all that beautiful, beautiful music man ....... 

 

[DRUB]

Quote:

Nothing is "buggered-up", what is wrong here is that this linear half wave power supply has gnat balls when HD650's require swinging truck nuts to sound their best. Sure some of you think it sounds clean and clear or whatever, but I feel you're not true connoisseurs of HD650 sound, if you were you'd know that this amp rates firmly in the nice-try-but-no-cigar category when driving HD650's. Unfortunately the amp simply won't sustain what is necessary to max out the HD650's.
 
Here is a comparative guide to assist your understanding of HD650's at their max:
 
BASS: The rumbling bass should call to mind an earth trembling buffalo stampede
MIDS: The flawlessly natural mids call to mind the luscious bosom of Gaia, our Earth Mother
TREBLE: And here the incorruptible treble seduces like Homer's sirens, transforming reality and reason
 
 
 
 

For the love of all that is good, please stop posting. You have buggered up your amp, lost any dignity you may have had left and yet you continue posting nonsensical crap like this.

 

[samsquanch]

Cheapskate:  Pics of underside and topside of board, and a list of changes you have made.  Even though I don't find this amp to be the be-all-end-all either, I don't think it's as flawed as you're saying (overheating and such), so you might have some issue that you're not noticing, maybe someone can point out a solder bridge/cold solder joint, or a component that might not work as is configured.

 

[francisdemarte]

Trying this now with the 18V AC power supply that came with the HiFiMan EF-5. Not noticing any improvements with sound but the regulators do run warmer, I can still touch them.
 
 

 

[kingpage]

Are people touching the regulators while it's on? Isn't that a bit dangerous?

 

[deadlylover]

Quote:

Are people touching the regulators while it's on? Isn't that a bit dangerous?

Nah it's perfectly safe, only stat amps can kill you.

 
My regulators got a little toasty, but nothing un-lickable, but I had the inputs at ~20VAC or so.

 

[fishski13]

Quote:

@Cheapskate
 
Wait a second, don't the regulators have thermal protection? I'm pretty sure they shut off when they get too hot rather than just let themselves burn out.
 
EDIT: Yup, they have thermal overload protection, in big letters on the first page of the datasheet. How on earth did you manage to fry them? 

if you read the datasheet under the max rating chart, these regulators can be damaged.  the power protection is "fail safe" for catastrophic conditions, not continuous out of spec operation.  a short in the circuit post regulator will cause over-heating, but i'm also wondering if people are leaving in the batteries continuously along with AC power, and what is the current draw in this state.