[MRC001]

Regarding opamps vs. discrete, and the audiophile myths that surround this topic, here is one of the best explanations I've read:
http://nwavguy.blogspot.com/2011/08/op-amps-myths-facts.html
I suspect many here are interested in this topic. It's just another opinion, but it's a well-informed one - written by a guy who designs and builds high quality headphone amps.
 
 

 

[Hooster]

All I know is that I have tried both and I know what I like. 

 

[frigginloony]

 

  well since the site says it has >120 DB my uneducated guess would be 0.552 for 10 db , 0.828 for 15 DB and 1.104 for 20 DB but be warned that's just a calculated guess and I would certainly contact Rothwell for correct figures on that Pancakes if the voltage is critical for you. 

Assuming they're measuring their attenuation dB as voltage, not power:
 
Vdb = 20 * log(V1 / V2)
So:
-10 dB would be a voltage ratio of 3.16:1, for example 1 V drops to 0.32 V.
-15 dB would drop 1 V to 0.18 V.
-20 dB would drop 1 V to 0.1 V.
 
Use the least amount of attenuation you can, to keep the voltage as high as you can, to keep the S/N ratio as high as possible.

See it pays to have someone who knows what they are talking about to answer questions intelligently rather than guessing  LOL.   Good work MRC! 

 

 

[OhMyGodPancakes]

   
2.8 V input to the HA-1 should be fine. The HA-1 specs on page 28 say the XLR input accepts up to 18 Vrms. The RCA input accepts up to 9 Vrms.
 
As for output, the HA-1 XLR output will vary from 0 to 4.6 Vrms, depending on the position of the volume knob.
 
The HA-1 should work just fine in your situation so long as you don't use bypass mode, and don't turn the volume up too high.

No I'm trying to control the HA-1 output. it's going to my A-S2000

 

[MRC001]

Quote:

  No I'm trying to control the HA-1 output. it's going to my A-S2000

 
So you want to drop 4.6 V (HA-1 max output voltage to balanced XLR line out) to 2.8 V (A-S2000 max input voltage)?
4.6 to 2.8 is a 4.3 dB reduction.
 
Are you really sure you need to reduce the voltage? It's a bit suspicious that the balanced XLR input of the A-S2000 has a max input voltage of 2.8 V. Balanced XLR inputs usually can handle much higher voltages. Are you sure that 2.8 V value is not the input voltage limit of the unbalanced RCA input?
 
Assuming 2.8 V is correct I suggest simply using the HA-1 volume knob. Don't crank it up too loud. You'd still have a wide range of usable volume knob motion. -4.3 dB would be your max, and that's more than 3/4 of the way around (past 3:00 position).
 
You can run the HA-1 in bypass mode so its XLR output is always full scale, and use a -6 dB attenuator on the HA-1 output to cut it to 2.3 V which gives you a little headroom below the A-S2000 max input voltage. The -10 dB attenuator will also work fine but it's a bigger reduction than you need. If you use an attenuator built with metal film resistors it should be transparent because the HA-1 has a low output impedance and the A-S2000 a high input impedance. But this adds needless complexity.

 

[OhMyGodPancakes]

Quote:

So you want to drop 4.6 V (HA-1 max output voltage to balanced XLR line out) to 2.8 V (A-S2000 max input voltage)?
4.6 to 2.8 is a 4.3 dB reduction.

Are you really sure you need to reduce the voltage? It's a bit suspicious that the balanced XLR input of the A-S2000 has a max input voltage of 2.8 V. Balanced XLR inputs usually can handle much higher voltages. Are you sure that 2.8 V value is not the input voltage limit of the unbalanced RCA input?

Assuming 2.8 V is correct I suggest simply using the HA-1 volume knob. Don't crank it up too loud. You'd still have a wide range of usable volume knob motion. -4.3 dB would be your max, and that's more than 3/4 of the way around (past 3:00 position).

You can run the HA-1 in bypass mode so its XLR output is always full scale, and use a -6 dB attenuator on the HA-1 output to cut it to 2.3 V which gives you a little headroom below the A-S2000 max input voltage. The -10 dB attenuator will also work fine but it's a bigger reduction than you need. If you use an attenuator built with metal film resistors it should be transparent because the HA-1 has a low output impedance and the A-S2000 a high input impedance. But this adds needless complexity.

Oh awesome thank you!

 

[Hooster]

  See it pays to have someone who knows what they are talking about to answer questions intelligently rather than guessing  LOL.   Good work MRC! 

 

 
 

  Quote:
 
 
Assuming 2.8 V is correct I suggest simply using the HA-1 volume knob. Don't crank it up too loud. You'd still have a wide range of usable volume knob motion. -4.3 dB would be your max, and that's more than 3/4 of the way around (past 3:00 position).
 
 

 
Which is what I said all along,"frigginloony". My advice to you is this:
 
1. Trust your own ears.
 
2. Learn something.
 
3. Once you know what your are doing, experiment and find out what works best for YOU.

 

[frigginloony]

 

  See it pays to have someone who knows what they are talking about to answer questions intelligently rather than guessing  LOL.   Good work MRC! 

 

 
 

  Quote:
 
 
Assuming 2.8 V is correct I suggest simply using the HA-1 volume knob. Don't crank it up too loud. You'd still have a wide range of usable volume knob motion. -4.3 dB would be your max, and that's more than 3/4 of the way around (past 3:00 position).
 
 

 
Which is what I said all along,"frigginloony". My advice to you is this:
 
1. Trust your own ears.
 
2. Learn something.
 
3. Once you know what your are doing, experiment and find out what works best for YOU.

Thanks Hooster. In order:
 
1. Trust your own ears.  -    Without fail, I always do
2. Learn something.  -   I Will stop learning when I quit breathing, and maybe not even then. I've been a good boy!  
3. Once you know what your are doing, experiment and find out what works best for YOU. -  My wallet tells me I've done way too much experimenting but at least, it has all worked out for whats best for me.

 

[Hooster]

  Thanks Hooster. In order:
 
1. Trust your own ears.  -    Without fail, I always do
2. Learn something.  -   I Will stop learning when I quit breathing, and maybe not even then. I've been a good boy!  
3. Once you know what your are doing, experiment and find out what works best for YOU. -  My wallet tells me I've done way too much experimenting but at least, it has all worked out for whats best for me.

 
Great post. The thing is that knowledge is power in more ways than one. You can sometimes upgrade your system significantly by buying and selling, make a profit, and end up with significantly better sound than you had before. Yes, sometimes you can actually have your cake and eat it.

 

[Shure or bust]

I enjoy the oppo HA-1, but I keep falling back to my experience with a Chord 2 qute hd and burson conductor with ess9018 and amp. The ess 9018 sounded terrible compared to the CHORD FPGA 64 chip running off the same amp. I am thinking how it would compare to the Oppo ha-1 in front of me right now. I prefer to listen to my HIFIMAN hm-802 with dual WM8740 DAC chips and mini box gold amp over the HA-1 currently. Probably gonna dump it soon at this rate. I rarely use balanced anyway. No need with iems and sub 100 ohm headphones.

 

[elucidate]

I can't seem to find any info regarding the HA-1's availability. Maybe it's been discontinued? Can anyone confirm/deny?

 

[Hifiaddict]

Yes it's discontinued but you can still find it on amazon some times or other places.
I bought one of the last ones 1 month ago in my local shop in Norway.

 

[elucidate]

Yes it's discontinued but you can still find it on amazon some times or other places.
I bought one of the last ones 1 month ago in my local shop in Norway.

That's ridiculous lol. Why produce a product for only three years. Seems ridiculous if you ask me.
 
Oh well. Thanks for the quick response (you just saved me a lot of time).

 

[Bombarde]

I agree - I'm very disappointed that they discontinued this, but very glad the I bought one last August. To my ears, it and the PM-1 are a match made in heaven.
 
There's a post earlier in this thread with a response from Oppo to an inquiry on it: http://www.head-fi.org/t/717834/oppo-ha-1-impressions-thread/4845#post_13223244
 
I hope that perhaps they come out with a replacement at some point. 

 

[aqsw]

Discountinued - That sucks. I sold mine because I wanted to upgrade, but it was a very good unit. The swiss army of headphone amps. Great features and great price for what you got.
What the hell is wrong with Oppo!!!