Jan Meier
King Corda
Member of the Trade: Meier Audio
- Joined
- Jun 21, 2001
- Posts
- 854
- Likes
- 182
Dear Kurt,
"It would seem that the battery will last quite a while...any estimates for this?"
The amp takes 9 ~ 10 mA current. Most 9V batteries are specified between 500 and 700 mAh so theoretically they should last at least 48 hours. Note that the amp has quite some power supply buffer capacity so even a near end-of-life battery (high internal resistance) doesn't sound too bad.
"Can you comment on the sound quality compared to the big-daddy Corda? Same ICs, I would guess it might be pretty close which would be super. "
There are two major differences:
1. The big CORDA has a regulated +15V -15V powersupply.
A nice thing of the Porta CORDA is the possibility to feed it with an external regulated power supply though.
2. The output stages of the opamps of the Porta CORDA are not driven into class-A mode as this would increase current consumption considerably. The big CORDA is thereby better in the fine details / microdynamics.
However, as a kind of compensation the potentiometer of the Porta CORDA is placed inside the feedback loop of the output opamp and not at the input. Thus signal levels inside are kept at a high level until the very last stage, even when listening sound level is low. Thus distortion and noise are minimized.
"What is the crossfeed level compared to the Corda? "
It's the medium level.
(The CORDA has stereo - low - medium - high)
" skippy running 6171's off of a +/-4.5v supply. amazing! "
Not truly, these amps are specified for both +/- 5V and for +/- 15V operation. Testing showed that the amp still works very nicely down to +/- 3V
The major reason for using the LM6171 in this specific application is the relatively large output current it still is able to deliver at +/- 4.5V. Thus I didn't need a DC-DC converter (very bad for sound and battery life) to create a higher supply voltage.
I didn't like the Grado solution to put two batteries in series as this would double battery consumption and increase the size of the amp. The amp now is so small, that it easily fits into a pocket.
Hi roll-man,
" So am I correct in understanding that if you just want the amp (I already have a pair of 580's), then the price is $160? Is there any "sales action" for head-fiers (and loyal Senn owners) on just the amp? "
Yes, you're correct. There's only a sales action in combination with the HD580. This phone thus effectively costs you $115,-.
Not too expensive, is it?
Dear tktran;
"Hope you have a fine day today "
Thanks, but I'm afraid it merely will be a very bussy one
Cheers,
Jan
"It would seem that the battery will last quite a while...any estimates for this?"
The amp takes 9 ~ 10 mA current. Most 9V batteries are specified between 500 and 700 mAh so theoretically they should last at least 48 hours. Note that the amp has quite some power supply buffer capacity so even a near end-of-life battery (high internal resistance) doesn't sound too bad.
"Can you comment on the sound quality compared to the big-daddy Corda? Same ICs, I would guess it might be pretty close which would be super. "
There are two major differences:
1. The big CORDA has a regulated +15V -15V powersupply.
A nice thing of the Porta CORDA is the possibility to feed it with an external regulated power supply though.
2. The output stages of the opamps of the Porta CORDA are not driven into class-A mode as this would increase current consumption considerably. The big CORDA is thereby better in the fine details / microdynamics.
However, as a kind of compensation the potentiometer of the Porta CORDA is placed inside the feedback loop of the output opamp and not at the input. Thus signal levels inside are kept at a high level until the very last stage, even when listening sound level is low. Thus distortion and noise are minimized.
"What is the crossfeed level compared to the Corda? "
It's the medium level.
(The CORDA has stereo - low - medium - high)
" skippy running 6171's off of a +/-4.5v supply. amazing! "
Not truly, these amps are specified for both +/- 5V and for +/- 15V operation. Testing showed that the amp still works very nicely down to +/- 3V
The major reason for using the LM6171 in this specific application is the relatively large output current it still is able to deliver at +/- 4.5V. Thus I didn't need a DC-DC converter (very bad for sound and battery life) to create a higher supply voltage.
I didn't like the Grado solution to put two batteries in series as this would double battery consumption and increase the size of the amp. The amp now is so small, that it easily fits into a pocket.
Hi roll-man,
" So am I correct in understanding that if you just want the amp (I already have a pair of 580's), then the price is $160? Is there any "sales action" for head-fiers (and loyal Senn owners) on just the amp? "
Yes, you're correct. There's only a sales action in combination with the HD580. This phone thus effectively costs you $115,-.
Not too expensive, is it?
Dear tktran;
"Hope you have a fine day today "
Thanks, but I'm afraid it merely will be a very bussy one
Cheers,
Jan
