[cosmopragma]

Currently I do have mOOhkOOh's W2002/HA2002 on loan.
There's no manual to speak of, only three pages mostly written in undecipherable japanese.
I do have a few questions regarding the amp.

1)The amp gets quite warm, warmer than the class A amps I'm familar with.
Is this normal?
2)The amp wants 100V.I'm powering it at the moment by utilizing a step down transformer I've once got in combination with a Stax set from Audiocubes.It is tiny and rated at 60W max.Are there transformers out there substantially and audibly better or doen't it matter in case of a step down transformer?
3)There are two different sets of RCA inputs at the back.One is labeled "DC direct", the other is labeled "AC coupled".What does that mean?
4)Are the HA2002 and the current HA5000 technically identical?
5)I've read dozens of times that the amp is synergistic with specific AT headphones but not versatile at all regarding other brands.
So far I've spent only a few hours with it but at the moment this seems to be a head-fi myth.
First of all the amp obviously isn't specifically designed to drive high sensitivity cans like the ATs.Way too much gain.All my songs are replaygained at a low 89 dB.I'm listening at 9 o'clock and that's already pretty loud.
Just for fun I've plugged some other cans into it.
Admittedly the K1000s do sound crappy when driven by this amp, but the other cans I had at my disposal did sound good.Especially and to my greatest surprise the K340s did sound very good, and from the specs they are as different from the ATs as it gets (400 Ohm, sensitivity 84 dB/mW).
Any thoughts about this?

Please don't answer if all you have to offer are hearsay and unsubstantiated assumptions.Assumptions are a dime a dozen and since I'm no newbie I could always create my own useless assumptions .........

 

[cosmopragma]

Where's the AT crowd when you need them?

 

[cosmopragma]

O.K., in five minutes I'll connect the DAC to the "AC coupled" jacks and when the DAC explodes I'll sue you since you didn't answer my questions ......

 

[JMcMasterJ]

I used DC Direct on my HA5000. I don't think it will make much of a difference which one you choose. From my understanding AC coupled has some kind of capacitor to block extremely low potentially damaging frequencies or prevent problems with DC offset whereas DC Direct doesn't have a capacitor and has a cleaner signal path.

 

[Macwizard]

I own the HA5000. Great amp.

1) It does run fairly warm, but should not burn you. Mosfet's usually run fairly warm.

2) My transformer is rated at 100W, but 60W should be fine because it is does not require much power. People love to talk about power cables and conditioners, but I don't believe it makes a hunge difference.

3) As stated above

4) There were some pictures posted a while back showing they looked exactly the same. I do believe they are the same design.

5) They run my l3000's and w5000's wonderfully. But my grado's sound awful. Sennheiser isn't bad, but a little colored.

 

[purk]

1)The amp gets quite warm, warmer than the class A amps I'm familar with.
Is this normal?
My HA2002 also gets quite warm so no need to worry there.

2)The amp wants 100V.I'm powering it at the moment by utilizing a step down transformer I've once got in combination with a Stax set from Audiocubes.It is tiny and rated at 60W max.Are there transformers out there substantially and audibly better or doen't it matter in case of a step down transformer?
I don't think you need one, but maybe the step down transformer will improve the sound. I've yet to try this myself.

3)There are two different sets of RCA inputs at the back.One is labeled "DC direct", the other is labeled "AC coupled".What does that mean?
I also use DC direct as the "AC coupled" has capacitor in the signal path..

4)Are the HA2002 and the current HA5000 technically identical?
They are very similar, but I don't think the inside is identical. I remember posting the internal picture of the HA2002 here and it looks almost the same as the inside of the HA5000, but some electronics look different.

5)I've read dozens of times that the amp is synergistic with specific AT headphones but not versatile at all regarding other brands.

They are made to work wonder with ATs headphones. I have good success using it with my L3000, W2002, W2002 (L3000 drivers), A100ti, A950LTD, W10VTG, and W11JPN. My HA2002 is at its best driving the W2002 and W11JPN though. I've also tried using the HA2002 with my R10 with very impressive result. I don't think my HA2002 did a good job driving the high impedance headphones though.

 

[cosmopragma]

Thanks for the answers.
I'll wait a few days until the new toy syndrom wears off before I'll audition it more critically.At the moment I am just enjoying it.It seems to drive the ATs even better than my Rudistor RPX33.

 

[purk]

Quote:

It seems to drive the ATs even better than my Rudistor RPX33.

Not surprising. The HA2002 drive my W2002 and W11JPN better than my Singplepower SDS.

 

[slwiser]

If you check out the circuitry you will see that it is a dual mono design. The R-Core transformer keeps isolation very well between the two sides. I know that many here do not think a design is dual mono unless you would have two R-cores but all the literature does not support this.

The HA2002 and the HA5000 have different power sections. This can be seen if you look at both the power boards coming off the R-Core transformer. I am not including the fact that the power board as been rotated 180 degrees from each other. The power coming into the the HA2002 and the HA5000 is also handled a bit differently. On the HA5000 both power leads go to the start button while on the HA2002 only a single lead goes to that button switch. Six cords (black while red, each) come out of the R-core on to the power board on the HA5000 while only four (blue while yellow and brown) go to the HA2002 power board. It appears that the ground is keep all the way to the power board from the R-core on the HA5000. Three leads each go from the power board to each of the amplifier boards on each side of the potentiometer.

The two boards on either side of the potentiometer are slightly different between the two amplifiers as well. The HA5000 has four small capacitors near the middle part of the channel's board that the HA2002 does not have. Two other brown capacitors have been move apart on the HA5000 compared with the HA2002. These are located just below the cluster of four near the very large ones, assuming the larges ones are away from you.

Just some observations on arrangement. I make no claims as to anything about quality differences.

HA5000

HA2002

 

[purk]

slwiser,
Thanks for your observation. I wonder what the sonic different b/w the two amps. The DHA3000 and HA2002 is quite a bit better than the HA2002 though.

 

[slwiser]

Quote:

Originally Posted by purk /img/forum/go_quote.gif slwiser, Thanks for your observation. I wonder what the sonic different b/w the two amps. The DHA3000 and HA2002 is quite a bit better than the HA2002 though.

My AT-HA5000 is doing a right good job with both my ATH-W5000 and my new Ultrasone Edition 9.

 

[Elephas]

I've had the chance to briefly compare the HA2002 with the HA5000, using the W2002. I was curious if the W2002 would be much better matched with its own amp instead of the HA5000.

The amps sound slightly different. It's not a big difference, but I thought the W2002 sounded better with the HA2002. Another person who listened preferred the W2002 with the HA5000.

Fortunately, I was able to resist the allure of the HA2002 and didn't end up on my knees begging the HA2002 owner to sell it to me.

 

[stevenkelby]

Quote:

Originally Posted by Macwizard /img/forum/go_quote.gif I own the HA5000. Great amp. 5) They run my l3000's and w5000's wonderfully. But my grado's sound awful. Sennheiser isn't bad, but a little colored.

Any idea why?

 

[purk]

Quote:

I've had the chance to briefly compare the HA2002 with the HA5000, using the W2002. I was curious if the W2002 would be much better matched with its own amp instead of the HA5000. The amps sound slightly different. It's not a big difference, but I thought the W2002 sounded better with the HA2002. Another person who listened preferred the W2002 with the HA5000. Fortunately, I was able to resist the allure of the HA2002 and didn't end up on my knees begging the HA2002 owner to sell it to me.

Yes, the HA2002 and W2002 do sound great together. The W2002 also work greats with W11JPN, W10VTG, and W5000. The HA2002 is a great match with the W2002 and W11JPN, IMO.

 

[slwiser]

Move internal pictures that are really close-up for the HA2002.

http://www.geocities.jp/ryumatsuba/column40.html