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Speaker amps for headphones - Page 125

post #1861 of 3116

My OSD Audio DSM4 has arrived! Got it off eBay for $58 shipped. The case is very thick, and has a quality anodized black finish. It also comes with a bunch of sticker labels for the different zones and an instruction sheet. It's strikingly similar to the Niles products, except those come with a 10 year warranty...meh. The connectors on the back are removable, so you can get a good tight grip and I suspect you can fit 12awg if you're careful, even though it says 14awg. The relays are sealed, and the defeatable protection circuit has 15w 10R resistors. Here are some pics for those interested :) I'll be hooking it up later in the week, so listening impressions will be coming soon.

Pics of OSD Audio DSM4 (Click to show)

 

 

 

post #1862 of 3116
What else does that company make the name looks familiar ?
post #1863 of 3116
Quote:
Originally Posted by ALRAINBOW View Post

What else does that company make the name looks familiar ?

You might be thinking of the DSM 4 which was the diagnostic bible for psychiatry? smily_headphones1.gif

I saw the OSD and thought of soundtracks - OST.
post #1864 of 3116
Lmao. I google it . I guess I'm havering another senior moment. They seem to be happening fast now.
post #1865 of 3116

So I tried some a vintage Nikko Alpha 230 Amp + Nikko Beta 30 PReamp that I found around my house and they sounded great with my LCD2s and plan on using them when I pick up my 009s. My issue is the controls on my pre-amp are not responding (Volume, bass, treble, balance, etc)

 

 


This a picture of the back I got off the internet

 

 

Im trying to figure out if I should plug my DAC into "Input" or under the Sound Processor "send" or "return"... or maybe its broken? I doubt it though because it played perfectly.

post #1866 of 3116
The sound professor loop must have a jumper in it . From output to I put. Also there should be a button on the front to bypass the Processor loop. If there is no button to bypass then the loop must be installed. Post the results
post #1867 of 3116

The preamp already has the Sound Processor button on the front to provide the loop when nothing is attached to the sound processor jacks on the back. Connect the DAC to the Tuner or the Aux inputs your choice. Do not use the phono inputs which is to be used only for turntables. Nothing needs to be plugin for the Tape 1 or Tape 2 inputs. Try using output 1 into the input of the amp below. Nothing is to be attached to the sound processor jacks.

post #1868 of 3116

I have updated the resistor network interface box DIY. I now have 3 versions of the box and they run from pretty simple to complex with V3:

 

RobinetteBox3Schematic.jpg

The Resistor Network Bypass switch removes the network from the headphone circuit. The Amp Mode switch allows: Single-Ended headphones with Single-Ended amplifiers, Balanced headphones with Balanced amps, and Single-Ended headphones with Balanced amps using the protective R5 resistors for the ultimate in flexibility. 


Edited by robrob - 12/12/13 at 7:34pm
post #1869 of 3116
Quote:
Originally Posted by robrob View Post
 

I have updated the resistor network interface box DIY. I now have 3 versions of the box and they run from pretty simple to complex with V3:

 

box pic (Click to show)
RobinetteBox3Schematic.jpg

The Resistor Network Bypass switch removes the network from the headphone circuit. The Amp Mode switch allows: Single-Ended headphones with Single-Ended amplifiers, Balanced headphones with Balanced amps, and Single-Ended headphones with Balanced amps using the protective R5 resistors for the ultimate in flexibility. 

Be careful of the toggle switches.  I've run across some that sound pretty bad.  Wish I had a recommendation for a good one, but I wouldn't recommend a switch without having tested it.  I'm sure @brunk or one of the other more seasoned DIY'ers can offer a suggestion...

post #1870 of 3116

Here's a Headphone Power Calculator spreadsheet:

 

You input your headphones' impedance and sensitivity (in either dB milliwatt or dB volt and it calculates the other sensitivity value). It also calculates the power and current at 1 volt rms. Input a target loudness and it'll give you the power, voltage and current required to get there using your headphones. You can also input an amplifier's Vrms rating and it'll give you the max headphone loudness and the power required to get there.

 

I hope you find this spreadsheet useful.

 

Rob Robinette

post #1871 of 3116
Quote:
Originally Posted by potterma View Post
 

Be careful of the toggle switches.  I've run across some that sound pretty bad.  Wish I had a recommendation for a good one, but I wouldn't recommend a switch without having tested it.  I'm sure @brunk or one of the other more seasoned DIY'ers can offer a suggestion...

I like the brand "NKK Switches". Here's their selection of DPDT Toggle Switches. If you want to get really fancy, add a Red/Green LED with a protective dome for a visual indicator if the protection is on or off :L3000: 

You could power the LED from a USB with a resistor or something


Edited by brunk - 12/12/13 at 8:34pm
post #1872 of 3116

Thanks for the link brunk. I ordered the ON-OFF-ON DPDT  and ON-ON 4PDT NKK switches with latching levers from them.

post #1873 of 3116
Quote:
Originally Posted by robrob View Post
 

Thanks for the link brunk. I ordered the ON-OFF-ON DPDT  and ON-ON 4PDT NKK switches with latching levers from them.

Sounds good! Let me know how you get on with this box. You can also create a BOM at Mouser and link it in the wiki. Mouser is usually a little cheaper than Digi-Key when ordering whole projects.

:beerchug:

post #1874 of 3116

@robrob One more thing. Since you are going all out in the versatility dept. of this box, consider adding a TRRS and the square 4-pin Hirose connector on the balanced side of the circuit. Then it will be truly universal!

post #1875 of 3116
Quote:
Originally Posted by brunk View Post

I like the brand "NKK Switches". Here's their selection of DPDT Toggle Switches. If you want to get really fancy, add a Red/Green LED with a protective dome for a visual indicator if the protection is on or off L3000.gif  
You could power the LED from a USB with a resistor or something

Hmmmm... It was an NKK DPDT switch that I didn't like. Diminished high frequency clarity and resolution compared to a reed relay. This was a silver plated copper contact version of the toggle switch. Maybe I should have gone good contacts?
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