[robrob]

10 ohm resistor + 32 ohm headphone = 7.6 ohms. 10 ohm resistor + 600 ohm headphone = 9.8ohms. Both will work fine with any tube amp designed for an 8 ohm load.

 

[DaemonSire]

  Just wondering has anyone else received any information from Brunk, about the Robinett Box ? Thanks

 
 

  Nope not yet. Haven't received any reply to my mails / pm's . Which is very unlike him, hope everything is all right with him.

 
Me too.  I haven't heard anything either and sent an email/pm's.  Hope everything is ok.

 

[robrob]

I sent brunk a pm too with no response so far.

 

[cute]

I added 8 ohm resistors to my tube amp speaker taps today, and it cleared up the distortion/osculation sounds I was getting in some of the lower mid vocals.  Whew, tried different tubes, cables headphones, and I though I damaged components.  Every thing sounds fine, very good now, clean background, same good sound from my music!  Thanks for the insight in this thread @robrob!

 

[robrob]

I'm glad it's working for you cute, but 10 ohm resistors would be a better match. 8 ohm resistors + 32 ohm headphones = 6.4 ohms of effective speaker load. Not low enough to do any harm but the cost of two 10 ohm resistors is just so low. . .

 

[cute]

  I'm glad it's working for you cute, but 10 ohm resistors would be a better match. 8 ohm resistors + 32 ohm headphones = 6.4 ohms of effective speaker load. Not low enough to do any harm but the cost of two 10 ohm resistors is just so low. . .

 
I couldn't find the 10 ohm;, I was in a hurry, so Amazon Prime was my alternative.  I had to settle for the cement, with short legs.  Now that I know the results, I can look for some of the black wire wound, or the pink in your picture.  Anyone have a link to either one of the two, 10 ohm, 10 watt? 

 

[Velomane]

Where would one buy wire-wound, non-inductive resistors? Even better if the vendor is in Canada, or at least the USA. The sites I've been to are vague about the non-inductive part. How important is this feature?

 

[robrob]

This a 10ohm 10watt 1% wirewound axial resistor for $1.74 each + shipping from Mouser.com 
 

 
http://www.mouser.com/ProductDetail/Ohmite/40F10RE/?qs=sGAEpiMZZMukHu%252bjC5l7YSNDdmoxLywgnEpqy8GgOKY%3d
 
You could get by with a 5watt resistor for your low power tube amp but the 10watt will work fine and also be good for a higher power amp in the future. If you do want a 5watt then search on mouser for "10ohm 5watt 1% resistor"

 

[cute]

  This a 10ohm 10watt 1% wirewound axial resistor for $1.74 each + shipping from Mouser.com 
 

 
http://www.mouser.com/ProductDetail/Ohmite/40F10RE/?qs=sGAEpiMZZMukHu%252bjC5l7YSNDdmoxLywgnEpqy8GgOKY%3d
 
You could get by with a 5watt resistor for your low power tube amp but the 10watt will work fine and also be good for a higher power amp in the future. If you do want a 5watt then search on mouser for "10ohm 5watt 1% resistor"

 
Thanks, I'm on it!

 

[Terja]

  Where would one buy wire-wound, non-inductive resistors? Even better if the vendor is in Canada, or at least the USA. The sites I've been to are vague about the non-inductive part. How important is this feature?

 
For a Canada-based vendor try Parts Connexion. Very friendly, easy to deal with and open to questions. Bought Mills resistors for my tube amp from there.

 

[DaemonSire]

  I sent brunk a pm too with no response so far.

 
hmm...that's weird...
 
I remember Brunk mentioning that he was doing a run of 15...has anyone heard anything?  That was 2 months ago now.

 

[rocksteady65]

   
hmm...that's weird...
 
I remember Brunk mentioning that he was doing a run of 15...has anyone heard anything?  That was 2 months ago now.

Hmm, yes, that's weird. Should we be worried?...

 

[rocksteady65]

To be fair, on his last PM to me, he stated that the work on the Boxes had only started on the 13th of March, due to delays on the delivery of speaker terminals. That makes it less than a month ago, so...

 

[hpandy]

I've read the bulk of this thread and I finally have a clear picture in my head of the different options.
 
My question is this: Why are the headpone outputs of integrated amps not already set up this way?  If it is so cheap and sounds so good, what is it that makes manufacturers do something different?
 
I opened up my arcam alpha 10 to take a look at the headpone socket, and all I see are 4 resistors.  Am I really doing anything different that what is already done inside the case by using the speakers taps?
 
The arcam alpha 10 is 100+ wpc in 8 ohms, can anyone guess as to how much attenuation I will need when driving a pair of audeze lcd-2?  Would it be safe to hook them up without?
 
(Additional none related query below)
 
 
Something that has been bugging me is that when people talk about the power requirements of headpones, they talk about the amount of power required to make a certain headphone reach a certain db.  Is this an average figure taken accross all frequencies, because I thought lower frequencies required more power? 
 
When somebody says x amount of power will produce y db output on these headphones, then in theory, could that not be true for the lower frequencies?
 
The reason I ask here is I wonder if this could be the reason that driving headphones from powerful speaker amps produces favourable results.
 
Cheers,
Andy

 

[manbear]

 
 
Something that has been bugging me is that when people talk about the power requirements of headpones, they talk about the amount of power required to make a certain headphone reach a certain db.  Is this an average figure taken accross all frequencies, because I thought lower frequencies required more power? 
 
When somebody says x amount of power will produce y db output on these headphones, then in theory, could that not be true for the lower frequencies?
 
The reason I ask here is I wonder if this could be the reason that driving headphones from powerful speaker amps produces favourable results.
 
Cheers,
Andy

Sensitivity is usually measured relative to 1000 Hz. It will definitely vary across frequencies, and the variation depends on the headphone's impedance curve. As far as I know, many headphones have an impedance peak somewhere in the bass frequencies due to driver resonance, so that peak would require more power.