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Grado HPA-1 & GS1000i

post #1 of 6
Thread Starter 

I'm currently using an RA-1 with my GS1000i headphones and would like some opinions regarding the HPA-1. 

 

From what I have gathered, generally, the HPA-1 has "less grain" than the RA-1.

 

From pictures I have seen of both amps, the HPA-1 appears to be better built even though it contains "the same circuit" as the RA-1.  The HPA-1 seems too use 4 capacitors instead of 2, like the RA-1.  Are the additional caps used to bypass the PS?  I also notice two small caps in parallel with the output.  I'm assuming these form a low pass filter on the output. 

 

Basically, is it worth trying to find an HPA-1 to replace my RA-1?

post #2 of 6

Yes, the HPA-1/2 is a far superior amplifier.

The RA-1 is good, but it was designed to sell at a reasonable price point and as such does not have the best components.

The HPA-1/2 were designed without limitations and use all the best sounding components that Joe Grado could find.

I am not 100% sure of the circuitry but it seems that the HPA-1/2 has two separate paths, one for 9V batteries and one for the power supply so it is in fact like getting two amps as far as quantity of components. 

The HPA-1 retailed for $795 (+$120 for the P/S-1) 20 years ago and Grado and they were still too expensive to make.

I have an HPA-2 with the P/S-1. It is a fantastic amp. It was also designed to drive the HP-1000 headphones which were not as efficient as today's Grados. As such, it will drive a wider variety of cans than the RA-1.

Well worth finding one, especially as they are not that expensive <$500.

 

post #3 of 6

I had forgotten about these amps.  Beauties..........

post #4 of 6

Very little has been said about the HPA-1 and -2 on Head-Fi.

 

It was designed by Sidney Stockton Smith, has a discrete circuit a bit simpler (or equivalent?) to a cMoy.

 

The RK40 potentiometer was the best ALPS made at the time (it's really smooth in its volume progression), they only sold them on mass orders so they weren't available to DIYers.

 

Anyway you can read this if you want:

 

It's definitely better than the HPA-1 in build quality (the metal chassis is really neat [the size of a DVD box, transportable with four 9 volts batteries in the compartment] and solid [feels like its going to last centuries], and it's very well "shielded" inside there); I don't know about the sound, sorry. And Parbaked is right, they can be had used (if you're lucky enough to find one of the 250 [100 HPA-2s, 150 HPA-1s] for sale, a few collectors have already secured theirs and hold on to them for really long) for relatively cheap.

 

I'm trying to make a power supply for mine, maybe the one of the RA-1 will work (with a retermination, I'm still in need of the HPAs' pin-out information) seeing it's also a ±12V and has a third auxiliary +5V pin.


Edited by devouringone3 - 2/24/13 at 10:40pm
post #5 of 6
Thread Starter 

I appreciate all the info.  I will definitely start actively searching for an HPA-1 or 2.  I really enjoy the sound of the RA-1/GS1000i combo and would like to stay with the Grado house sound.

 

Parbaked, have you compared an RA-1 to your HPA-2?  What's the biggest improvement?

 

Devouringone3, a PS shouldn't be too difficult to build if you know the voltages.  Power-One makes some nice linear power supplies and I'm pretty sure they have one with +/-12 and 5v outputs.  I recently bought a 12v version to replace the cheap wall wart of my clearaudio turntable.  I boxed it up in a nice aluminum case and it works really well.  Maybe someone on here can supply the pin outs for you.

post #6 of 6
Quote:
Originally Posted by ECM View Post

I appreciate all the info.  I will definitely start actively searching for an HPA-1 or 2.  I really enjoy the sound of the RA-1/GS1000i combo and would like to stay with the Grado house sound.

 

Parbaked, have you compared an RA-1 to your HPA-2?  What's the biggest improvement?

 

Devouringone3, a PS shouldn't be too difficult to build if you know the voltages.  Power-One makes some nice linear power supplies and I'm pretty sure they have one with +/-12 and 5v outputs.  I recently bought a 12v version to replace the cheap wall wart of my clearaudio turntable.  I boxed it up in a nice aluminum case and it works really well.  Maybe someone on here can supply the pin outs for you.

The HPA-1/2 is more neutral/flat and has tremendous detail and tonal weight. There is so much detail that it sounds lush, serious and business-like. It's a tool for critical listening.

I remember the RA-1 to be more fun and colored (not in a bad way). more like a toy for enjoyment.

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