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Speaker amps for headphones - Page 176

post #2626 of 2717

Solid state for the most part does not care what the load is nor does it care if there's no load attached.

 

Tube amps can be finicky. As a very general statement, OTL tube amps want to see a specific load for optimum performance. Some transformer coupled amps may have specific desired loads as well. Sometimes, these "dummy loads" are built directly into the amp. But sometimes not. Transformer coupled amps also generally do not like to run without any load attached, and may also have dummy loads built in, but sometimes not.

 

In the speaker world, usually you attach the speakers to the amp and leave it there and that's it. So even if you have a transformer coupled tube amp, chances are you never run it without a load so there isn't too much to worry about. With headphones though, we have this annoying habit of unplugging the headphones which brings the risk of running the amp without a load which can potentially blow the transformers or the tubes or both.

 

So thus the quick fix is to slap a resistor on the outputs. Most safe bets say to put a 10ohm resistor (of at least 5 or 10W rating) across the outputs of each channel. Just this by itself doesn't offer any attenuation though.

 

The other popular arrangement is the L-pad. Google it for a dozen websites that tell you how to build one with built-in calculators and schematics. Basically you use two resistors to create a voltage divider for your headphones, If you pick the resistors carefully, you can also get a decent damping factor and come close to the desired amp load if required. Sometimes getting all that with two resistors is tricky though, so a three resistor arrangement might be used.

 

And then there's my stance on the whole thing: don't pick a huge amp that necessitates those resistors to begin with. If there's too much gain on the amp or you have noise issues, pick a different amp.

post #2627 of 2717
Quote:
Originally Posted by Armaegis View Post
 

Solid state for the most part does not care what the load is nor does it care if there's no load attached.

 

Tube amps can be finicky. As a very general statement, OTL tube amps want to see a specific load for optimum performance. Some transformer coupled amps may have specific desired loads as well. Sometimes, these "dummy loads" are built directly into the amp. But sometimes not. Transformer coupled amps also generally do not like to run without any load attached, and may also have dummy loads built in, but sometimes not.

 

In the speaker world, usually you attach the speakers to the amp and leave it there and that's it. So even if you have a transformer coupled tube amp, chances are you never run it without a load so there isn't too much to worry about. With headphones though, we have this annoying habit of unplugging the headphones which brings the risk of running the amp without a load which can potentially blow the transformers or the tubes or both.

 

So thus the quick fix is to slap a resistor on the outputs. Most safe bets say to put a 10ohm resistor (of at least 5 or 10W rating) across the outputs of each channel. Just this by itself doesn't offer any attenuation though.

 

The other popular arrangement is the L-pad. Google it for a dozen websites that tell you how to build one with built-in calculators and schematics. Basically you use two resistors to create a voltage divider for your headphones, If you pick the resistors carefully, you can also get a decent damping factor and come close to the desired amp load if required. Sometimes getting all that with two resistors is tricky though, so a three resistor arrangement might be used.

 

And then there's my stance on the whole thing: don't pick a huge amp that necessitates those resistors to begin with. If there's too much gain on the amp or you have noise issues, pick a different amp.

Well written advice, Armaegis! And I thank you for that. I am commissioning a pigtail adaptor for my HD600 and will go about trying SS amps to be safe.

post #2628 of 2717
Quote:
Originally Posted by Rossliew View Post

Thanks for the tip. I read somewhere before where resistors are not necessary for OTL type of amps?

In general, is it correct to say solid state amps don't require this resistor?

Solid state and OTL tube amps do not need the loading resistor.

If your tube amp does need a loading resistor I would stick with a two resistor network, for example, 2 and 10 Ohms.
Even tube amp that need a load do NOT need a precise value, I.e. It does not need to Elbe exactly 8 Ohms if the output transformer is optimized for an 8 Ohm load.
post #2629 of 2717
Quote:
Originally Posted by Chris J View Post


Solid state and OTL tube amps do not need the loading resistor.

If your tube amp does need a loading resistor I would stick with a two resistor network, for example, 2 and 10 Ohms.
Even tube amp that need a load do NOT need a precise value, I.e. It does not need to Elbe exactly 8 Ohms if the output transformer is optimized for an 8 Ohm load.

Many thanks. Chris.

post #2630 of 2717
Quote:
Originally Posted by Gary in MD View Post
 

I got mine off Amazon from Shenzen:

 

http://www.amazon.com/Upgrade-Version-balance-ZY-002-2-5M/dp/B00A2QJLY8/ref=sr_1_11?ie=UTF8&qid=1406087641&sr=8-11&keywords=hd650+cable

 

It's a really nice cable.  I have to believe Shenzen will ship one to Australia for about the same price (in USD).


Ordered!

 

Thanks Gary. I hope the Cyclops wakes up my 650. Cheers!

post #2631 of 2717
Looks like a nice cable. I should check it out for my 600.
post #2632 of 2717

Hi guys! I would appreciate some help with my current home setup as I'm kind of a novice when it comes to using speaker amps for headphones. I'm currently using a HRT music streamer HD connected single ended (RCA) to an Elekit 22 hybrid stereo AMP (not much specs available, but rated power output is 12W/channel @8Ohms). With this I'm using a pair of LCD-3 rev 1 (2011 model, pre fazor) hooked up straight to the speaker terminals of the amp using 2x banana to 3 pin XLR adapter.

 


I'm REEALLY loving the sound this combination outputs, but as always on head-fi, we constantly try to improve what we can (am I right? :D). The thing I'd like to improve is hiss. At normal listening levels it is barely noticeable but if I crank the volume a bit (when playing volume levelled tracks for instance) the hiss gets a bit more noticeable at silent passages. Is this something that can be tamed with series or parallell resistors? Preferably, I'd like to use something that doesn't require a lot of soldering, like this:


Again, I'm quite new to this so I appreciate all the help I can get!

regards

/Emil

post #2633 of 2717
If your hiss increases with volume knob position, it may not be the fault of the amp but an upstream component. If you pause your source does it go away? If you turn off your source does that make it go away?
post #2634 of 2717
Quote:
Originally Posted by potterma View Post

If your hiss increases with volume knob position, it may not be the fault of the amp but an upstream component. If you pause your source does it go away? If you turn off your source does that make it go away?

Hiss increases with the volume knob, even if I disconnect all inputs. Seems to vary slightly depending on which input I'm using (3.5 mm aux or RCA).

post #2635 of 2717
Quote:
Originally Posted by esmBOS View Post

Hiss increases with the volume knob, even if I disconnect all inputs. Seems to vary slightly depending on which input I'm using (3.5 mm aux or RCA).

 



is the hiss in both channels? tubes can make some noise.
post #2636 of 2717
Quote:
Originally Posted by gjc11028 View Post
 
Quote:
Originally Posted by esmBOS View Post
 

Hiss increases with the volume knob, even if I disconnect all inputs. Seems to vary slightly depending on which input I'm using (3.5 mm aux or RCA).

is the hiss in both channels? tubes can make some noise.

Yes, it's very symmetrical. The amp uses two 6SN7 tubes and I haven't had the chance to try it with many different tubes yet. Only a pair of budget Shuguang's I got from ebay and they are very noisy (hum+hiss). The EH 6SN7's that the amp came with are dead silent when it comes to hum. Just figured I'd ask here if there is any resistor magic I can apply to maybe reduce the slight hiss (it really isn't that bad). 

Are resistors (parallel/series) used solely to create headroom for the volume knob?

post #2637 of 2717
It's a 12 watt hybrid? Not a lot of power in the ss stage..
Resistors should reduce hiss (not in parallel, though), but if the noise increases as volume rises it might not help that much.
Edited by davidsh - 8/26/14 at 7:11am
post #2638 of 2717
Quote:
Originally Posted by davidsh View Post

It's a 12 watt hybrid? Not a lot of power in the ss stage..

Yes a 12W hybrid. Don't know about the ss stage, but overall it's got tons of power. Even drives my full size floorspeakers to sadisfactory volume levels. You mean the hiss can be due to weak ss stage?

post #2639 of 2717

If the noise is still there without the source connected its the amp.  If it is the source, try a source with optical in.  If not the source and you dont hear noise with less sensitive headphones/speakers, LCD is too sensitive for the gain of the amp.  I dont see how a series resistor would help as all its doing is ceating a voltage divider decrasing volume of signal and noise, and just gives volume more range as result.


Edited by SilverEars - 8/26/14 at 8:02am
post #2640 of 2717

Sounds to me that the noise you are experience is due to the tubes themselves.  Just to rule out any upstream affect, disconnect the HRT DAC and short out the inputs.  Then slowly turn up the volume to see if the noise is still there.  If noise is no longer there, then it's your upstream device(s).  If noise still exist, IMHO, it's the tubes that are causing the noise.  SS output devices usually are very quiet.

 

I also agree with member Armgaeis on top of this page to use a 10W resistor (typically used for tube amps) directly across the output of your amp.  This will not provide any reduction in noise nor attenuation but will help in the damping factor.  Your LCD has a Z of 50 ohms? and putting the 10 ohms resistor will allow your amp to see a more of 8 ohm load for which it was meant to drive.

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