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HE-500, LCD2, D5000, DT770, SR80, on a speaker amp (Emotiva mini-X A-100) Project - Page 172

post #2566 of 3639
Quote:
Originally Posted by SolidVictory View Post
 

 

Thanks for the help. Looks like for this amp, I should go with a 2 ohm for Resistor 3, and 6 ohms for Resistor 2. This reaches the effective speaker load of 7.9 ohms which is nearly 8 ohms.

 

This creates an attenuation of -12.37 dB, which I think should be sufficient.

 

Can this even be done on a single cable or would you need some type of enclosure?

If you are careful with the connections, sure you can do it in the cable.  Just make sure everything is insulated with heatshrink so you don't end up with a direct short.  Also, upsize the resistor power dissipation rating, since everything would be insulated and won't have the chance to dissipate heat as if it were in free air.

post #2567 of 3639
Quote:
Originally Posted by potterma View Post
 

If you are careful with the connections, sure you can do it in the cable.  Just make sure everything is insulated with heatshrink so you don't end up with a direct short.  Also, upsize the resistor power dissipation rating, since everything would be insulated and won't have the chance to dissipate heat as if it were in free air.

 

Eh, I was thinking of having someone build the cable. I would love to learn how to use an external resistor on the amp, but having never done so, I wouldn't know where to start, what to buy, and how to attach it to the speaker terminals on my amp. And I have a myriad of floating questions like: Would I be able to use banana terminated plugs on an external resistor? How would I check the values from an external resistor? Etc.

 

Would be great if there was a guide to all this, but it looks like it's just dispersed throughout several threads on this forum.

post #2568 of 3639

Proof ;) The pics are pretty bad, though

 

post #2569 of 3639
Quote:
Originally Posted by davidsh View Post
 

Proof ;) The pics are pretty bad, though


 

eeeek! (Click to show)

 

  yikes!

post #2570 of 3639
Quote:
Originally Posted by SolidVictory View Post
 

 

Eh, I was thinking of having someone build the cable. I would love to learn how to use an external resistor on the amp, but having never done so, I wouldn't know where to start, what to buy, and how to attach it to the speaker terminals on my amp. And I have a myriad of floating questions like: Would I be able to use banana terminated plugs on an external resistor? How would I check the values from an external resistor? Etc.

 

Would be great if there was a guide to all this, but it looks like it's just dispersed throughout several threads on this forum.

 

Yes, a nice succinct guide would be nice.  The closest thing that exists, that I'm aware of it the "Speaker Amps for Headphones" thread.  Unfortunately, it does take a while to dig through all the info there.

 

If you mentioned it, I must have missed it, or just don't recall... What amp are you using? The Mini-X?

post #2571 of 3639
Quote:
Originally Posted by davidsh View Post
 

Proof ;) The pics are pretty bad, though

 

 

Ouch, damn. I'm still not quite sure how that happened, though. Did you just accidentally switch channels, or did you cause a short between them?

 

I'm trying to find out what I should *not* do.


Edited by Taowolf51 - 12/8/13 at 3:00pm
post #2572 of 3639

 Quite bad, a good part of the diagram circle in shaped also melted

post #2573 of 3639
Quote:
Originally Posted by john57 View Post
 

 Quite bad, a good part of the diagram circle in shaped also melted

 

I'm not really sure whether it is the x-can as pre-amp doing weird stuff or if it was a short. Just know i connected right and left positives to the same channel, the negatives as well. Can't quite figure out what that'd do so late at night, lol. The emo did go into protection mode.

 

Quote:

Originally Posted by john57 View Post
 

 Quite bad, a good part of the diagram circle in shaped also melted

It doesn't appear to have melted from sight. Well, it has melted around the conductors in the alu film I suppose..


Edited by davidsh - 12/8/13 at 3:02pm
post #2574 of 3639

davidsh,

it saddens me to read about your bad experience :-(

I don't quite understand what when wrong for you, so here's a dumb question:

Did you use your Musical Fidelity as a pre-amp and thus not feed your amp with a line-out signal?

I only ask because I once made that mistake with a speaker system - fortunately my speakers didn't blow...

post #2575 of 3639
Pre-out, not line-out. Will check whether the pre-out works properly tomorrow.
post #2576 of 3639
Quote:
Originally Posted by potterma View Post
 

 

Yes, a nice succinct guide would be nice.  The closest thing that exists, that I'm aware of it the "Speaker Amps for Headphones" thread.  Unfortunately, it does take a while to dig through all the info there.

 

If you mentioned it, I must have missed it, or just don't recall... What amp are you using? The Mini-X?

 

I'm planning on using an old home theater amp I have which sounds great: Yamaha RX-V1200 (specs here).

post #2577 of 3639
Quote:
Originally Posted by davidsh View Post
 

 

I'm not really sure whether it is the x-can as pre-amp doing weird stuff or if it was a short. Just know i connected right and left positives to the same channel, the negatives as well. Can't quite figure out what that'd do so late at night, lol. The emo did go into protection mode.

 

Did the driver of the channel that had both positives blow?

post #2578 of 3639
Quote:
Originally Posted by SolidVictory View Post
 

 

I'm planning on using an old home theater amp I have which sounds great: Yamaha RX-V1200 (specs here).

If I were you, I'd get a balanced cable for the HE-500 if you don't already have one, and a XLR to banana adapter (Blue Jeans Cable is a good source) and just try it.  If the Yamaha has a low noise floor, and you've got enough volume knob to play with, you won't need resistors :)

post #2579 of 3639
Quote:
Originally Posted by davidsh View Post
 

 

I'm not really sure whether it is the x-can as pre-amp doing weird stuff or if it was a short. Just know i connected right and left positives to the same channel, the negatives as well. Can't quite figure out what that'd do so late at night, lol. The emo did go into protection mode.

 

Quote:

Originally Posted by john57 View Post
 

 Quite bad, a good part of the diagram circle in shaped also melted

It doesn't appear to have melted from sight. Well, it has melted around the conductors in the alu film I suppose..

 If you look at the shiny part of the diagram around the hole you can see it is like a circle. Not the dull part.  If the protection mode did not react quickly enough the fuses will blow in the amp. Mine came with two spare fuses. Emotiva built the amps to last.

post #2580 of 3639
Quote:
Originally Posted by davidsh View Post

Never got that upa-2. You know what happens when you accidentally short a 125 watt power amp with he-500? It blows. Well, not the amp, but the phone does.. Just don't hope my x-can has taken damage as well. There's literally blown a hole in one of the diaphragms. Cannot figure out whether my x-can works properly either. Let's see how good Hifiman warranty really is :S
I've done this. Didn't short out the amp but put too large a signal to the amp and blew a hole in a driver. It cost $130 to replace. Most of that, shipping.
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