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Advice on choosing a portable amp that uses a 9V - Page 2

post #16 of 42

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Edited by labrat - 9/15/11 at 2:48pm
post #17 of 42
Thread Starter 

(Attenuation) Understood. I would also like to drive my T1s when I travel. I have an m902 at home, and use decent sources when traveling. 


Edited by audiogamma - 10/17/10 at 12:54pm
post #18 of 42
Quote:
Originally Posted by labrat View Post




How do you know?

Powerex 9.6 Volts Rechargeable NiMh:

 

http://www.mahaenergy.com/store/viewitem.asp?idproduct=273


 

There are many variants, but all I am saying is that there is a "true" 9v battery.

post #19 of 42

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Edited by labrat - 9/15/11 at 2:46pm
post #20 of 42

OK yes I should have prefaced that with rechargable, which is what we are talking about here, only the insane people use alkaline in portable amps tongue.gif I use lifepo4, which have a nominal voltage of 3.3, but start at 3.6 and are at the end of their useful charge at 3.05v. of course I use 4 of them in series, for ~14v @2300mah


Edited by qusp - 10/17/10 at 9:14pm
post #21 of 42
We should not confuse gain and attenuation with power. Some IEMs do respond well to quality power which is why a high end portable amp like the Stepdance can make a meaningful difference - even if volume is attenuated.
Edited by cooperpwc - 10/17/10 at 9:34pm
post #22 of 42

According to some on these threads, the Stepdance is a battery-eater.  Around 10 or so hours per charge.  I personally don't know because I don't own one, but read some of the Stepdance threads and that's what's being said on these.

 

Personally, I like the Hornet.  Put a rechargeable in the thing and forget it.  Battery can be recharged while in the amp with no need to remove it.  And get the rechargeable that's 9.6 v.  iPower I think, but check all the rechargeables on Thomas Distributing's website

post #23 of 42

hmm, I dont know that it should make all that much difference if you use 9.6 v or 8.4, the amp will have a regulator that is set to put out a steady voltage below 8.4 v, probably something like 7 or +/-3.5v it will put out the same voltage whether you have 8.4 or 9.6, all having 9.6 in there will do is cause more energy to be burned off as heat in the reg. the power supply caps are doing the heavy lifting as far as current too, NIMH has crappy output impedance, so would need to be backed up with quality power supply circuitry.

post #24 of 42

I'll cast my vote in for the Meier portable, any of them, used or new.

post #25 of 42
Quote:
Originally Posted by qusp View Post

hmm, I dont know that it should make all that much difference if you use 9.6 v or 8.4, the amp will have a regulator that is set to put out a steady voltage below 8.4 v, probably something like 7 or +/-3.5v it will put out the same voltage whether you have 8.4 or 9.6, all having 9.6 in there will do is cause more energy to be burned off as heat in the reg. the power supply caps are doing the heavy lifting as far as current too, NIMH has crappy output impedance, so would need to be backed up with quality power supply circuitry.


I do not believe that this is true of the Stepdance. It operates at up to 15 volts (DC regulated) on a fixed power supply, and as low as 6  volts on a fixed supply and even just 5 volts on battery. I doubt that it would regulate batteries downwards. 
 


Edited by cooperpwc - 10/18/10 at 7:31am
post #26 of 42

well if not, then thats a disadvantage IMO, I was giving the benefit of the doubt as Jan is a good designer as I believe he is. I dont think you understand what i'm saying due to lack of electronics knowledge (not a slight at you), the rails are either completely unregulated bar smoothing/buffering from the PSU caps, which given the reviews seems unlikely, or there is some voltage dropped accross regulator, that is unavoidable, unless there is a switching DC charge pump to lower the current and up the voltage (bad for audio as HF switching noise needs filtering out), there will always be some voltage drop over the regulator, the reg needs this power to do its job. now its possible that he has just used a rail splitter and buffered that with an opamp to produce a stiff ground reference, leaving the caps to do the work (not the battery either) for the rail voltages. or he uses a more complicated (and IMO superior) design in which the rails are regulated too (resulting in the voltage out of the reg, being slightly lower than what went in, now LDOs (low drop out regs) minimize this to maybe 100-200mv (sometimes less) but still something has to give

 

 

given its a portable amp and batteries are pretty clean, if not so stiff, power supply, that in an effort to keep things streamlined, he has used unregulated rails, but used a decent amount of low impedance capacitors, with only an active rail splitter (buffered ground) 

 

in either case, the batteries are not doing the work, caps in the case of the passive solution and regulators plus caps in the case of the active one. though the voltage will indeed be higher with a 9.6v battery, if passive and unregulated

 

 

anyway enough OT from me, sorry guys


Edited by qusp - 10/18/10 at 8:52am
post #27 of 42

oh just one thing, good results can be had either way, I just happen to have a preference for the active solution

post #28 of 42
You are right: it is not a slight because I really do not know. :-)

(I thought that I could extrapolate from the 6-15 volt flexibility fot the (regulated) power supply but perhaps not. I do know that Jan strongly prefers linear over switching. )
post #29 of 42

cool, just wanted to make sure it wasnt taken as a sideways swipe, as can be traditional here biggrin.gif yeah I would say if there are regs, they would be linear, shunts are too wasteful for portable (even more voltage dropped) and switching DC pump is just downright bad for low noise audio. so its either a linear reg, or none at all with the caps doing all the heavy lifting. well the 9-15v thing could indeed mean no reg at all if thats what you mean, but it could also mean that when an external regulated power supply is connected, there are different supply lines and the battery is disconnected, thats what happens in the fiQ and lisa III and really any portable that is designed to take advantage of higher voltages when available 

 

enough 'amp whispering' from me though. enjoy the music!! I do do that too BTW, I love tweaking hardware, but I could not live without the music


Edited by qusp - 10/18/10 at 12:19pm
post #30 of 42

I don't see where anyone suggested the Ray Samuel's SR-71A which uses 2 (yes 2) 9volt batteries. I enjoy both the SR-71A and the Stepdance but as everyone knows, the battery in the Stepdance does not last very long before it is exhausted. The SR-71A on the other hand lasts a good long while.

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