[Fearless1]

HI all,
 
Been lurking here for a while. This is my first real post so go easy on me

. My question for anyone who can answer is; I was looking for a muti station/amp for my Denon AH-D5000 Reference phones that I just got in a trade for some car audio equipment. These sound amazing BTW.
 
I impulse bought an Aphex 454 off of E-bay because these Denons run at 25ohms and I wanted an amp that can run at a lower impedence. I read that this units distortion (THD+N, 1 kHz) is specified at less than 0.001 percent when driving a 25-ohm load with 100 mW.
 
Good match? Has anyone else used this amp?
 
Any input would be greatly appreciated.

 

[weissglut]

Hey,
I'm interested in this amp, too. Here is a link to their website: http://www.aphex.com/products/model-454/
 
 

Input Z	Bal: 20k ohms; Unbal: 10k ohms
Output Z	10 Ohms
Maximum Input Level	Bal & Unbal: +24dBu
Frequency Response	10Hz - 120kHz ±1dB
SNR (typical)	100dB
Crosstalk, dB	-80 @ 1kHz; -70 @ 10kHz
Maximum Gain	35 dB
THD+N, 1kHz	< 0.001%, 100mw into 25 ohms
SMPTE IMD	< 0.001%, 100mw into 25 ohms

Who can tell me more? 

 

[Fearless1]

Quote:

Hey,
I'm interested in this amp, too. Here is a link to their website: http://www.aphex.com/products/model-454/
 
 

Input Z	Bal: 20k ohms; Unbal: 10k ohms
Output Z	10 Ohms
Maximum Input Level	Bal & Unbal: +24dBu
Frequency Response	10Hz - 120kHz ±1dB
SNR (typical)	100dB
Crosstalk, dB	-80 @ 1kHz; -70 @ 10kHz
Maximum Gain	35 dB
THD+N, 1kHz	< 0.001%, 100mw into 25 ohms
SMPTE IMD	< 0.001%, 100mw into 25 ohms

Who can tell me more? 

It was actually a mess. The one i bought  sounded horrible, very high hiss sound even at low volume.  I do not recommend.
 

 

[weissglut]

Thanks for your info

 

[weissglut]

Well, I've boght one at ebay for 45 € only. I have no problem with hiss, even on my 35 Ohm phones. The amp has a lot of power for my 300 Ohm headphones.
 
Pictures:
https://picasaweb.google.com/lh/photo/vvkcXUNwhceD7LygYqWrEdMTjNZETYmyPJy0liipFm0?feat=directlink
https://picasaweb.google.com/lh/photo/0AHlyur4Tb6NMZv-CkwYrNMTjNZETYmyPJy0liipFm0?feat=directlink
https://picasaweb.google.com/lh/photo/uiE6r3nGzGQgBifxVuLcP9MTjNZETYmyPJy0liipFm0?feat=directlink
https://picasaweb.google.com/lh/photo/kFP8PSW9X0ZdzQnHeDYn79MTjNZETYmyPJy0liipFm0?feat=directlink
https://picasaweb.google.com/lh/photo/1l-oxGZvHMjoj1XNS_1uzdMTjNZETYmyPJy0liipFm0?feat=directlink
https://picasaweb.google.com/lh/photo/sbGP1vkonrkOuKqIXBUkwNMTjNZETYmyPJy0liipFm0?feat=directlink
https://picasaweb.google.com/lh/photo/VZwAj_nh6fIZ_pyM7hgS7NMTjNZETYmyPJy0liipFm0?feat=directlink
https://picasaweb.google.com/lh/photo/CoQKIT7LZvK8gikUdnRGwdMTjNZETYmyPJy0liipFm0?feat=directlink
 

 

[weissglut]

After having a look athe pictures I guess it's built like this:
* it has an 16V AC trafo wall adapter
* power input section features 2 diodes, 2 big capacitors and 2 low dropout regulators to create a +15V and a -15V rail
* balanced input uses an additional NE5532 op-amp
* unbalanced input goes directly to the preamp, consisting of a OPA2134 op-amp for voltage gain and a LF353 op-amp as buffer for the output stages
* output ICs seem to be TI TPA6120 (the label was sanded off)
 
Any thoughts/corrections?

 

[Fearless1]

I must have got a bad one. Mine had a lot of hiss and  the channels cut out one by one (only the far right one works). I was very unhappy with this one.

 

[weissglut]

Well, the quality of the THT component soldering is not the best I've seen 

 So it really may be possible you had a bad one. Most reviews I've found were good and I think it's a nice amp, too. Especially for the 45 € I've paid

 

[stv014]

Quote:

I must have got a bad one. Mine had a lot of hiss and  the channels cut out one by one (only the far right one works). I was very unhappy with this one.

Maybe the 100 dB SNR is specified at the maximum output level. But the 35 dB gain is quite high, perhaps it can be reduced, lowering the noise ? In any case, it does look basically like an overpriced FiiO E9.