[Andrea]

Here's Alberto's reply to my inquiry about this possibility.

Quote:

Yes, we had a look at doing customized as a special order feature and we can for a price of course and on a limited basis (small orders). Not sure yet how much of a market there would be though, will be interesting to see. We do not stock these chips and so we have to order them as and when requested by the customer. We can get them in 2 business days and will take us 1 or 2 business days for turning around the modified amp (depending on other workload). For the AD823/LMH6654MA combination you are looking at an added cost of US$32 for us to modify the 0HA-REP, so total before shipping would be US$121.99 For the AD8620/LMH6654MA combination you are looking at an added cost of US$46 for us to modify the 0HA-REP, so total before shipping would be US$135.99 And, we will provide a customized specifications data sheet to go with the amp. Will also carry our standard 5 year warranty.

I think that's an opportunity for others to get to hear the sound of the op-amp configurations I've spoken of lately.

 

[spyder9]

Will any of these combinations improve bass? I just bought a Xenos REP. Though I like the cleaner, crisper sound of the midrange and treble, I noticed the Xenos sheared off some bass. My rig is Shure E3C and Creative Labs Nomad Zen (the original w/ firewire). The difference in bass without the Xenos in the middle was very noticeable.

So which of the chips above will improve bass?

 

[Andrea]

Though it's not the amp itself that's bass lean, but rather that the Creative DAP has surely a slightly boosted bass in its headphone out (at least with low impedance headphones attached) - a headfier said that the standard 0HA-REP's bass would improve with burn in (becomes fuller).


At any rate, if you want more bass, the first thing to do is substitute in the LMH6654's, that are more powerful & visceral than the stock LMH6642's. The next is to replace the OPA2134 with the AD823.

 

[Filburt]

Quote:

Originally Posted by Andrea /img/forum/go_quote.gif a headfier said that the standard 0HA-REP's bass would improve with burn in (becomes fuller).

But then again, head-fiers say all manner of things 'improve' with 'burn in' ;D

To the OP - Try swapping in an OPA2107.

 

[JLai]

How does the 3HA compare to the REP? Have you heard both?

 

[Andrea]

As I haven't ever tried it even though I have a couple... Fliburt, does the OPA2107 work fine @ 12V?

 

[Andrea]

Quote:

Originally Posted by JLai /img/forum/go_quote.gif How does the 3HA compare to the REP? Have you heard both?

Yes and from memory I prefer my modified 0HA-REP for the HD650.

 

[JLai]

Quote:

Originally Posted by Andrea /img/forum/go_quote.gif Yes and from memory I prefer my modified 0HA-REP for the HD650.

What about stock vs stock?

 

[Andrea]

Quote:

Originally Posted by JLai /img/forum/go_quote.gif What about stock vs stock?

The 3HA was more powerful (I guess it could drive even some speakers!), probably clearer too. I'd give it the edge over the stock 0HA-REP.

 

[hciman77]

Quote:

Originally Posted by spyder9 /img/forum/go_quote.gif Will any of these combinations improve bass? I just bought a Xenos REP. Though I like the cleaner, crisper sound of the midrange and treble, I noticed the Xenos sheared off some bass. My rig is Shure E3C and Creative Labs Nomad Zen (the original w/ firewire). The difference in bass without the Xenos in the middle was very noticeable. So which of the chips above will improve bass?

Is this conecting to the amp through hadphone out or line out ?

 

[IEATTEFLON]

AD8620+LMH6654 is $16 at digikey in single quantity. For $46 increase what else is changed from stock other than different chips?

 

[spyder9]

Quote:

Originally Posted by hciman77 /img/forum/go_quote.gif Is this conecting to the amp through hadphone out or line out ?

Headphone out.

 

[spyder9]

Quote:

Originally Posted by Andrea /img/forum/go_quote.gif Though it's not the amp itself that's bass lean, but rather that the Creative DAP has surely a slightly boosted bass in its headphone out (at least with low impedance headphones attached) - a headfier said that the standard 0HA-REP's bass would improve with burn in (becomes fuller). At any rate, if you want more bass, the first thing to do is substitute in the LMH6654's, that are more powerful & visceral than the stock LMH6642's. The next is to replace the OPA2134 with the AD823.

Thank you Andrea!

 

[NelsonVandal]

I've just ordered AD8620 + AD8397 from Analog and LMH6654 + LM4562 from National. I'm going to try your favourite combination AD8620/LMH6654 in my Xenos. Have you abandoned the 8620. Is AD823 your new baby. What's your impressions of it?

This will be my first mod. Are any tweaks necessary, or can I just switch the chips?

 

[Andrea]

I tried the AD823 only with the AD8397's in the buffer position (those did require some tweaks to the circuit, and besides at 18 mA current draw each they warmed up a little bit much for my taste).

No I wouldn't prefer the AD823 to the AD8620 - I think. I haven't had the opportunity to do AD823 + LMH6654 (I'm done with modding!). But knowing the sonic signatures of the chips involved, AD823 & LMH6654 should be happy together.

Since you ordered the LM4562, you could also go with LM4562 + LMH6654.


In any event (if you leave the AD8397 out) no tweaks are required. Just desolder the old chips and solder the new - and don't consider me responsible if you fail