Aleph 1 or 1.2 on Infinity IRS
Friend of mine operates a Infinity IRS III (not a typo it's a 3, not the more "common" 5) with a Threshold SA/4 on his Mid/High EMIM/EMIT wings.
He wants to have Aleph 1's now because he heared an Aleph 2 stereo on his IRS's and was very impressed. He says his IRS mid/hig section can dip down to 2 Ohms (I asked him where that is frequency wise) so he needed the specified push-pull 600 Watts at 2 Ohm rating of the three stage Aleph 1 and the two stage 1.2 being troughout single-ended Class A would have maybe problems in that area.
I deduced at this forum that the Aleph 1.2 is preferred soundwise.
Any thoughts/suggestions?
Friend of mine operates a Infinity IRS III (not a typo it's a 3, not the more "common" 5) with a Threshold SA/4 on his Mid/High EMIM/EMIT wings.
He wants to have Aleph 1's now because he heared an Aleph 2 stereo on his IRS's and was very impressed. He says his IRS mid/hig section can dip down to 2 Ohms (I asked him where that is frequency wise) so he needed the specified push-pull 600 Watts at 2 Ohm rating of the three stage Aleph 1 and the two stage 1.2 being troughout single-ended Class A would have maybe problems in that area.
I deduced at this forum that the Aleph 1.2 is preferred soundwise.
Any thoughts/suggestions?
I've seen a review about the original XA160 (singel-ended amp) from Stereophile and they measured the following output power:
" Fig.3 shows how the XA160's measured THD+noise percentage changes with measured output power. (The wall AC voltage was 124V for these measurements.) The actual output power at clipping (defined as 1% THD+N) was 165W into 16 ohms, 118W into 8 ohms, 59W into 4 ohms, and 29W into 2 ohms. As I've said, the two amps measured virtually identically in this respect, meaning that this is unlikely to be due to a sample fault. [A subsequent e-mail from Nelson Pass concerned the fact that early samples of the amplifier suffered from a production error, resulting in the low maximum power. This has been corrected, Iw as told.—JA.]
Fig.3 Pass Labs XA160, distortion (%) vs 1kHz continuous output power into (from bottom to top at 10W): 16 ohms, 8 ohms, 4 ohms, 2 ohms.
The shortfall in power delivery into 8 ohms is 1.3dB, which is not really much of a difference. However, the Wilson WATT/Puppy 7 speaker used by MF for his auditioning is basically a 4 ohm load, so I'm somewhat surprised that the Pass Labs amplifiers didn't sound as if they were running out of power. All I can think of is that 60W is still enough power for the Wilsons to reach satisfyingly loud levels in his room. But as all these power figures (other than the 16 ohm result) are equivalent to a current of 3.8A—way below the 12A specified—it looks as if the XA160's clipping-free power delivery is current-limited. Combinations of low-impedance speakers and large rooms should be avoided with the XA160."
As I understand also from the Owners Manual of the XA160 (and XA200 for that matter) the power output stays the same with 16, 8, 4 and 2 Ohms and NOT like Stereophile measured is that the correct assumption?
Would a XA160 broadly speaken deliver the same power-output as the Aleph 1.2?
" Fig.3 shows how the XA160's measured THD+noise percentage changes with measured output power. (The wall AC voltage was 124V for these measurements.) The actual output power at clipping (defined as 1% THD+N) was 165W into 16 ohms, 118W into 8 ohms, 59W into 4 ohms, and 29W into 2 ohms. As I've said, the two amps measured virtually identically in this respect, meaning that this is unlikely to be due to a sample fault. [A subsequent e-mail from Nelson Pass concerned the fact that early samples of the amplifier suffered from a production error, resulting in the low maximum power. This has been corrected, Iw as told.—JA.]
Fig.3 Pass Labs XA160, distortion (%) vs 1kHz continuous output power into (from bottom to top at 10W): 16 ohms, 8 ohms, 4 ohms, 2 ohms.
The shortfall in power delivery into 8 ohms is 1.3dB, which is not really much of a difference. However, the Wilson WATT/Puppy 7 speaker used by MF for his auditioning is basically a 4 ohm load, so I'm somewhat surprised that the Pass Labs amplifiers didn't sound as if they were running out of power. All I can think of is that 60W is still enough power for the Wilsons to reach satisfyingly loud levels in his room. But as all these power figures (other than the 16 ohm result) are equivalent to a current of 3.8A—way below the 12A specified—it looks as if the XA160's clipping-free power delivery is current-limited. Combinations of low-impedance speakers and large rooms should be avoided with the XA160."
As I understand also from the Owners Manual of the XA160 (and XA200 for that matter) the power output stays the same with 16, 8, 4 and 2 Ohms and NOT like Stereophile measured is that the correct assumption?
Would a XA160 broadly speaken deliver the same power-output as the Aleph 1.2?
Okay let me rephrase my question:
If my friend with the Infinity IRS III’s wants to drive his mid/high section with a single-end amplifier from Pass Labs would an Aleph 1.2 or a XA160 be a better choice from a technical standpoint? He’s not listening at eardeafening levels but is mainly interested in very good sound and in particular a very good soundstage.
If my friend with the Infinity IRS III’s wants to drive his mid/high section with a single-end amplifier from Pass Labs would an Aleph 1.2 or a XA160 be a better choice from a technical standpoint? He’s not listening at eardeafening levels but is mainly interested in very good sound and in particular a very good soundstage.
XA160 should be best but not possible to say without testing the two. XA160 is best of both Aleph and SUSY worlds. Of course what version of the XA will matter.
XA160 should be best but not possible to say without testing the two. XA160 is best of both Aleph and SUSY worlds. Of course what version of the XA will matter.
He wants the single-ended versions so that limits his choice between the Aleph 2.1 and the first XA-160 without the .5 or .8 designation.
I've never seen a XA-200 but that would be even better maybe.
He first said to me that the XA160 would not be possible on his IRS because it doubles down its power when the load halves based on that Stereophile review (https://www.stereophile.com/solidpoweramps/1103pass/index.html) I quoted.
I remembered that NP stated probably in the manufacturers section of the magazine, that these had todo with a production error in the first run of these XA160's so I gather that this has been corrected and the XA160 will deliver around 160 Watts in 8, 4 and 2 Ohms as stipulated in their manual.
If the XA160 can drive his mid/high sections of his Infinity IRS III also his choice will be somewhat broaden and the XA160 looks prettier too ;-)
He wants the single-ended versions so that limits his choice between the Aleph 2.1 and the first XA-160 without the .5 or .8 designation.
I've never seen a XA-200 but that would be even better maybe.
He first said to me that the XA160 would not be possible on his IRS because it doubles down its power when the load halves based on that Stereophile review (https://www.stereophile.com/solidpoweramps/1103pass/index.html) I quoted.
I remembered that NP stated probably in the manufacturers section of the magazine, that these had todo with a production error in the first run of these XA160's so I gather that this has been corrected and the XA160 will deliver around 160 Watts in 8, 4 and 2 Ohms as stipulated in their manual.
If the XA160 can drive his mid/high sections of his Infinity IRS III also his choice will be somewhat broaden and the XA160 looks prettier too ;-)
XA160
mosfet based SUSY FE, OS halves are Aleph
yeah, halves are SE, but entire amp being SUSY, bridged, not much of difference regarding sum result, comparing to later UGS+source follower constructions
differences being more in realm of how particular amp being voiced in factory, than from differences in topology of blocks
intrinsically - thingie is so symmetrical that zilch of SE sound could go out
but, we all know that intrinsic factors can be deliberately altered, as Pa always did, so how much of SE sound is creeping out, it really needs to be matter of listening test, not (unbased) contemplating about topologies
power - whatever load is , see max. figures for V and A, so whatever clipping (V or A) happens at specific load, that's max power; for 16R clip voltage defined, for 4R clip current defined (back of napkin calc sez 98W@4R, 78W@16R)
snip from Owner Manual:
*********************************
Gain 26 dB
Freq. Response -3 dB at 1.5 Hz, -3 dB at 100 kHz
Power Output 200 watts maximum @ 1% THD, 1 kHz, 8 ohms
Distortion @ 1 KHz 0.01% @ 10 W, 0.1% @100 W, 1% @ 200 W
Maximum Output Voltage plus, minus approx. 50 volts
Maximum Output Current plus, minus approx. 7 amps
Input Impedance 22 kohm balanced
11 kohm unbalanced
Damping factor 30 ref @ 8 ohms nominal
Slew rate approx. plus, minus 50 V/uS
Output Noise approx. 300 uV unweighted 20-20 kHz
Random noise floor approximately 2 uV
Dynamic range 155 dB (random noise floor to peak output)
Balanced CMRR approx. -60 dB @ 1 kHz (input common mode rejection ratio)
DC offset < 100 mv
Power Consumption approx. 550 watts
Temperature 25 degrees C. above ambient at idle
********************
mosfet based SUSY FE, OS halves are Aleph
yeah, halves are SE, but entire amp being SUSY, bridged, not much of difference regarding sum result, comparing to later UGS+source follower constructions
differences being more in realm of how particular amp being voiced in factory, than from differences in topology of blocks
intrinsically - thingie is so symmetrical that zilch of SE sound could go out
but, we all know that intrinsic factors can be deliberately altered, as Pa always did, so how much of SE sound is creeping out, it really needs to be matter of listening test, not (unbased) contemplating about topologies
power - whatever load is , see max. figures for V and A, so whatever clipping (V or A) happens at specific load, that's max power; for 16R clip voltage defined, for 4R clip current defined (back of napkin calc sez 98W@4R, 78W@16R)
snip from Owner Manual:
*********************************
Gain 26 dB
Freq. Response -3 dB at 1.5 Hz, -3 dB at 100 kHz
Power Output 200 watts maximum @ 1% THD, 1 kHz, 8 ohms
Distortion @ 1 KHz 0.01% @ 10 W, 0.1% @100 W, 1% @ 200 W
Maximum Output Voltage plus, minus approx. 50 volts
Maximum Output Current plus, minus approx. 7 amps
Input Impedance 22 kohm balanced
11 kohm unbalanced
Damping factor 30 ref @ 8 ohms nominal
Slew rate approx. plus, minus 50 V/uS
Output Noise approx. 300 uV unweighted 20-20 kHz
Random noise floor approximately 2 uV
Dynamic range 155 dB (random noise floor to peak output)
Balanced CMRR approx. -60 dB @ 1 kHz (input common mode rejection ratio)
DC offset < 100 mv
Power Consumption approx. 550 watts
Temperature 25 degrees C. above ambient at idle
********************
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Proof is in the pudding....
So it's 200 Watts at 8 Ohms according to the manual and you calculated 98 Watts at 4 Ohms and 78 Watts @ 16 Ohms.
That means its power transfer is optimized for 8 Ohms and at 4 Ohms it does go in half compared with the 8 Ohm powerrating?
The Aleph 1.2 according the owners manual:|
"Power Output 200 watts/ch 8 ohms, 300 watts/ch 4 ohms"
everything goes from specifically declared figures of 100Vpp voltage envelope and 14A current envelope
Maximum Output Voltage plus, minus approx. 50 volts = 100 Volts peak to peak
Maximum Output Current plus, minus approx. 7 amps = 14A peak to peak
And then I need some kind of program to calculate the clipping powers for 2, 4, 8 and 16 Ohms 😉
Napkin won't do it for me...
Maximum Output Current plus, minus approx. 7 amps = 14A peak to peak
And then I need some kind of program to calculate the clipping powers for 2, 4, 8 and 16 Ohms 😉
Napkin won't do it for me...
if you read again, you'll see that I already did it for 4, 8, 16 Ohms
and gave ya specific formula
14A pushed through 2R results in 28Vpp
28Vpp = 14Vp = 10Vrms
10^10/2=50
W
@
2
R
and gave ya specific formula
14A pushed through 2R results in 28Vpp
28Vpp = 14Vp = 10Vrms
10^10/2=50
W
@
2
R
Aleph 1.2 is certainly current limited at 4R
you can get rms current from power figure, same as that you're calculating power of your heater
P=I^2 * R
means Irms is 8A66
so, for 2 ohms, same logic, 8A66^2 * 2R = 150W
Aleph 1.2:
24A trough 4R = 96Vpp
96Vpp = 58Vp^0.707 = 41Vrms
41^41/4 = 420 Watts at 4 Ohms
So it must be current limited as you state
24A trough 4R = 96Vpp
96Vpp = 58Vp^0.707 = 41Vrms
41^41/4 = 420 Watts at 4 Ohms
So it must be current limited as you state
May I conclude that for the mid/high section of the IRS III which dips at 2.5 Ohms at 125 Hz and stays around 3 Ohms till 4 kHz (see graphs in post 3), the Aleph 1.2 is better suited amplifier with regard to that impedance curve? It will simply deliver more current at every load into those IRS towers.
Thanks ZM for this lecture on very basic amplifier figures... 😏
It's hard to grasp that such a big amplifier with a huge PSU can only put out 50 Watts @ 2 Ohms.
But if you count in it's single-ended and bridged it makes sense.
It's hard to grasp that such a big amplifier with a huge PSU can only put out 50 Watts @ 2 Ohms.
But if you count in it's single-ended and bridged it makes sense.
well, there is a Bentley ....... and there is a Hummer
size and weight comparable
choice, depending of your target group, where you think you can be more laid
I can tell the same for IRS III ...... speakers so big, doing so little judging by their size
size and weight comparable
choice, depending of your target group, where you think you can be more laid
I can tell the same for IRS III ...... speakers so big, doing so little judging by their size