Speaker amps for headphones
Feb 12, 2014 at 5:30 PM Post #2,431 of 3,873
Looks cool brunk. And no comment to the other post .

Al
 
Feb 12, 2014 at 11:23 PM Post #2,432 of 3,873
Looks cool brunk.

Al

Thanks Al. I found some spare time to finish up the modules and it's looking good! Here's some speaker amp audiophile porn for you Head-Fi'ers :)
 
16 Watts of Class A amplification per channel, > -120dB distortion and crosstalk, flat from DC-100khz and 15dB of gain. Fully balanced from input to output. Yeah, I'm optimistic!
Oh, and I'll be checking out the HE-6 with it before I hook up the analog active x-overs. 
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Feb 12, 2014 at 11:45 PM Post #2,433 of 3,873
I was thinking to myself the other day I could hook up a bunch of hypex ncores... but oh wait, I don't have the speakers for it
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One step at a time, one step at a time.
 
Feb 12, 2014 at 11:52 PM Post #2,434 of 3,873
  I was thinking to myself the other day I could hook up a bunch of hypex ncores... but oh wait, I don't have the speakers for it
rolleyes.gif
One step at a time, one step at a time.

Hehe! Yeah, dreaming about a build like this and putting it in the physical world with your hands is a pretty cool thing :)
 
There's approx. 1,000 solder points on this project, so it was (and still is) quite the enjoyable work! 
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Feb 13, 2014 at 12:03 AM Post #2,435 of 3,873
I actually try not to tackle big projects (at least not lately). I get sort of obsessive and have a terrible habit of powering through projects and trying to finish them in a couple marathon sessions, which is bad because I seem to forget about everything else (like eating and sleeping).
 
I don't know if it's enjoyment or just feeding the ocd sometimes...
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Feb 13, 2014 at 12:05 AM Post #2,436 of 3,873
  I actually try not to tackle big projects (at least not lately). I get sort of obsessive and have a terrible habit of powering through projects and trying to finish them in a couple marathon sessions, which is bad because I seem to forget about everything else (like eating and sleeping).
 
I don't know if it's enjoyment or just feeding the ocd sometimes...
blink.gif

Haha, I do that sometimes too. It helps those late night jitters for sure 
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Feb 13, 2014 at 7:55 PM Post #2,437 of 3,873
PM6004 review to come by next Sunday. In the meanwhile, check out Luxman L-505uX. If you have the money to spend, should give this a shot. Sounds good with LCD-3. Really holographic and remarkable treble. Also, another NAD amp (forgot the model number) - it goes for around $800 and has 70/80W. - good bass response. Transparent. Nothing strident. 
 
All comparison done with NAD M51.
 
Feb 14, 2014 at 8:36 PM Post #2,439 of 3,873
Damn - I just drink. Will have to learn how to solder now !

LOL 
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Update:
For those of you interested in a speaker amp to headphones adapter box, I am offering to build the Robinette v3 box for $94 shipped if you live in continental USA since I have been getting alot of PMs about it.  Just drop me a PM. I will ship international too.
 
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Feb 15, 2014 at 8:24 AM Post #2,440 of 3,873
I'm not sure if I mentioned this before but to make it official, the Robinette Box is open source hardware under the Creative Commons permissive license and is open to royalty-free commercial use.
 
I apologize for dual posting this here and in the HE-500 Mini-X thread.
 
Here's the Robinette Box Instructions:
 

Instructions

WARNING: You must set the Amplifier Mode Switch before connecting your amplifier to the Robinette Box. An incorrect switch setting can damage a balanced output amplifier and your headphones.
Before connecting the Robinette Box to an amplifier set the Amplifier Mode Switch' to match the amplifier you are connecting to. The switch is used to switch between amplifiers with single-ended output and amps with balanced output. The switch only needs to be changed when moving the Robinette Boxto a new amplifier. The switch has a latching lever to prevent accidental movement so the lever must be pulled outward slightly to change switch positions.

Set the Amplifier Mode Switch

1. Single-Ended Output Amplifier. Switch lever toward TRS headphone jacks. Use this position for amplifiers with single-ended output (common ground).  All three headphone jacks are active.
 
WARNING: Only use this switch position when connected to an amplifier that has its black speaker terminals tied together (common ground or single-ended). Selecting this position while connected to an amp with balanced output can damage your headphones and amplifier. You can verify the amp's black speaker terminals are tied together by using a multimeter's continuity test. With the amp unplugged touch the multimeter's probes to the black speaker terminals. If you get the continuity beep your black speaker terminals are tied together and it's safe to use the single-ended amp switch position. If you do not get continuity your amp has balanced output and you should not engage this mode. Your amp's schematic diagram will also show a ground symbol connected to the black speaker posts. More info on balanced versus single-ended amplifier output can be found here.
 
2. Balanced Output Amplifier with Balanced Headphones. Switch lever centered. Use this for amplifiers with balanced output (non-common ground). Only the XLR jack is active. The TRS headphone jacks' combined ground is disconnected to protect the amplifier.
 
3. Balanced Output Amplifier with Single-Ended Headphones. Switch lever toward XLR jack. Use this position when you need to use single-ended headphones with an amplifier that has balanced output. The balanced amplifier is protected from the TRS jacks' combined ground by resistors R5. All three headphone jacks are active.

Set the Network Bypass Switch to the Down position (resistor network active)

Switch Up = Network Bypass. XLR and TRS connectors are directly connected to the speaker binding posts.
 
Switch Down = Resistor Network Active. Attenuation L-pad 'Preferred Resistor Network' is switched into the circuit.
 
WARNING: The headphone volume will jump by 12.4 decibels when the Network Bypass Switch is moved to the Bypass position. Turn the amplifier volume down before selecting the Bypass position.
 
Note: With the Network Bypass Switch down (network active) it is safe to run your amplifier with no headphones connected because the amplifier will be given an 8 ohm load by the resistor network.

Connect the Robinette Box to your amplifier

With the Amplifier Mode Switch set properly connect the box to your amplifier's speaker terminals. The Robinette Box speaker binding posts will accept single and dual banana plugs, spades and raw wire up to 10 gauge. When viewing the box from the front (the end with headphone jacks) the right speaker posts are on the right and the left are on the left. The upper binding posts are for the amplifier connection, the lower binding posts are optionally used to connect your speakers.

Connect your headphones to the Robinette Box

Turn your amplifier volume full down then power it up

Turn the volume up slowly to keep from overpowering and possibly damaging your headphones. Remember to turn the amplifier volume down before changing position of the Network Bypass Switch.

Enjoy your headphones and speaker amp

The Robinette Box is open source hardware under the Creative Commons permissive license and is open to royalty-free commercial use.
 
Feb 21, 2014 at 11:45 PM Post #2,441 of 3,873
Folks:
 
Just wanted to say that I am currently listening to the HD-650s driven by the TBI MIllenia MG-3 using the Mills resistor box, and I can say that for the HD-650s, I like this particular combination MUCH more than I like either the MIllenia/concrete resistors or the Odyssey Cyclops.  The Cyclops reveals harshness and sibilance in the HD-650s that the Millenia takes out somewhat with the concrete resistors, but completely with the Mills box.  If you have HD-650s this is an excellent combination. If you are thinking of building a Robinette Box for HD-650s you might want to think about plunking down a few extra bucks for the Mills resistors.
 
I still much prefer the LCD-3/Cyclops combo over any of the others.  Unfortunately, however, my stock LCD-3 balanced cable crapped out this week, so the LCD-3s are out of commission with the Odyssey.  Note that Audeze is sending me a new cable at no charge.  Those guys have tremendous customer support.  In the meantime, I'm enjoying the HD-650s with the TBI/Mills combo while I wait for the new cables to show up.  Definitely a more-than-adequate backup.
 
Feb 22, 2014 at 2:28 AM Post #2,442 of 3,873
Hey Gary,
 
I'd forgotten that you have two TBI resistor boxes. The HD650 can be really surprising on the right system.
 
My MG3's (concrete) resistor network continues to dissappoint me.  When I use the HD650 to compare the headphone out of the Bushmaster MkII with the MG3 > resistor box (concrete), I can readily detect a loss of dynamics and to a lesser degree, a loss of resolution.  Perhaps the Mills resistors would improve matters, but I've pretty much retired my MG3 to permanent duty as a speaker amp, where I'm thrilled with its performance.  
 
Meanwhile, the Bushmaster MkII > iBasso PB2 Pelican, equipped with Muses02 op-amps and dummy buffers, is working great for both the LCD-2 and HD800 - though still not ideal for the HD800 - the fault of the headphone, not the amps I've thrown at it.  
 
It's amazing that, after several headphone amps and speaker amps, I'm settling in on a $250 DAC/amp and a $325 portable amp (with $167 worth of op-amps) as my favorite desktop system (albeit with a $650 Concerto as USB-to-SPDIF convertor, but there are much less expensive options that would likely nearly as well - like the HiFiMeDIY USB DAC and SPDIF Converter).
 
Enjoy your Mills resistors - and thanks for the tip - I'll remember to go with Mills wirewound in the future.
 
Mike
 
Feb 22, 2014 at 7:30 AM Post #2,444 of 3,873
I hAve that amp it's really good with iem,s . I use it with my hdpr10. It really brings the best of that dap. I never tried it with the he 6 or hd800.
I could if needed to.
Has anyone tried the JOB225 amp. It is supposed to be like the second coming of amps .

Al
 

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