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head amp for hd650 beside sr-71A blackbird or p-15
Sep 6, 2010 at 2:59 PM Post #16 of 23


rockincannoisseur said:
so r u saying the protector is a lot more powerful than the p51? and is alo rx also more powerful than p51, protector, pico?

thanks

damn just when im about to pull:frowning2:
and do u also find the protector to have more ppower than the p51 and is the alo rx more powerful than protector/p51/pico?

thanks
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Yes, I know the Protector is a lot more powerful than the P51. I don't have experience with ALO RX but the above post seems to think it doesn't match well.

But several offerings in the last months definitely peak my interest and seem to deserve your serious attention also: the Ibasso DB1/PB1 combo which is within the op budget and the Meier Stepdance. I am also wwaiting for the SR71b. Good luck with your pursuit.
 
Sep 6, 2010 at 3:13 PM Post #17 of 23
I had a Predator with the HD650 and I thought that it drove them quite well. From what I've read, the P51 is more powerful than the Predator. Actually, I've read that the P51 is actually a very nice and powerful little portable amp. I sold my Predator Friday night and purchased an SR-71a not 10 minutes later here on the FS forum. Should be here Wednesday. From what I've read also, the SR-71a is one of if not the most powerful portable amp there is (not counting the not so portable Lisa III). I would recommend it. I'll know a little more about the two together on Wednesday.
 
Sep 6, 2010 at 3:21 PM Post #18 of 23
The FIRST thing you need to look at in knowing how powerful a portable amp is is the power supply voltage.  Huh why is this rarely published?
 
2xAA NIMH = 2.4V
2xAA = 3V
Single cell li-ion/li-po = 4.2V (max)
4xAA NIMH = 4.8V
4xAA = 6V
Dual cell li-ion/li-po = 8.4V (max)
9V = 9V
2x9V = 18V *
 
* Most amps that run on 18V do not swing rail to rail, meaning they are not capable of converting 100% of power supply voltage to audio output voltage (14-15V is typical).  These days most amps running on 9V or less are more or less capable of this.
 
The next thing is obviously current output capability, but I would worry less about this as portable amps, especially the ones on lower supply voltages, tend to be voltage limited if you haven't already blown your ears out.
 
I posted this because I've seen 1 amp called "powerful" and another called "weak" when they have the EXACT SAME POWER OUTPUT.  You have to look beyond the marketing words and presentations and find the simple facts
 
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Sep 6, 2010 at 5:12 PM Post #19 of 23

 
Quote:
justin w. said:
The FIRST thing you need to look at in knowing how powerful a portable amp is is the power supply voltage.  Huh why is this rarely published?
 
2xAA NIMH = 2.4V
2xAA = 3V
Single cell li-ion/li-po = 4.2V (max)
4xAA NIMH = 4.8V
4xAA = 6V
Dual cell li-ion/li-po = 8.4V (max)
9V = 9V
2x9V = 18V *
 
* Most amps that run on 18V do not swing rail to rail, meaning they are not capable of converting 100% of power supply voltage to audio output voltage (14-15V is typical).  These days most amps running on 9V or less are more or less capable of this.
 
The next thing is obviously current output capability, but I would worry less about this as portable amps, especially the ones on lower supply voltages, tend to be voltage limited if you haven't already blown your ears out.
 
I posted this because I've seen 1 amp called "powerful" and another called "weak" when they have the EXACT SAME POWER OUTPUT.  You have to look beyond the marketing words and presentations and find the simple facts
Click to expand...


Does the SR-71a swing rail to rail? I bought 4 Tenergy NiMH rechargeable batteries to use in my SR-71a. They are rated at 8.4V. If the SR-71a doesn't truly output 18V, does this mean that I shouldn't notice a difference when using these 8.4V batteries instead of using Duracell Coppertop alkaline batteries? Thanks.
 
Sep 6, 2010 at 8:08 PM Post #20 of 23
^ From my experience with my SR-71A, I don't think it'll matter because this amp is powerful enough that I have rarely used high gain. Low gain works nicely with IEMs.
 
I use a pair of Tysonic 9V 200MAH  NiMH and iPowerUS 9V 500MAH Li-Polymer
 
With my iPod Classic, line out to the SR-71A, with  demanding bass-heavy electronic music, in med. gain I'm getting approx. 90 dB. into my Beyer T1 @ 3 O'clock on the volume.In testing this, my Li-Polymer were not at full charge and above this volume the amp began to clip.
 
I think you'll be happy cycling your pairs of Tenergy.
 
Sep 6, 2010 at 8:31 PM Post #21 of 23
I couldn't find tysonics to save my life!! I searched and searched and searched! What is the voltage output of the ipowerus 9v's? Are they easy to find? Expensive? I paid $34 shipped for 4 Tenergy 250mah 9v rechargeables and a 4 slot recharger. Which I think was pretty good. They do only output 8.4v though. From what I've read it shouldn't make much of a difference in the sr71a.
But anyway, where do you find these tysonics and ipowerus batteries? Thanks.
 
Sep 6, 2010 at 10:01 PM Post #23 of 23
Thank you sir
 
One more thing: I've read on here that Ray doesn't recommend Lithium batteries in his amps as they could overheat and damage the battery connects. Also, in response to Justin's comment, does anyone know if the sr71a outputs a full 18V's? Does it swing rail to rail or whatever? Thanks. Sorry to threadjack!
 
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