Opamps and Modding thread.

Hi guys, my first post in this thread, although I have looked in a few times.

Yesterday I got some NewclassD Dexas for my Minimax Tube DAC Plus.
(they are not Class D opamps, if anything they sound more analogue, thats their company name unfortunately lol)
http://www.hificollective.co.uk/components/newclassdopamps.html
http://www.newclassd.com/index.php?page=55
I had to get both single and dual sets as my DAC needs both when not using the tube, so not cheap.
They arent burned in yet, so these are preliminary results.

Immediately I noticed that when music is playing everything is better defined/crisper and the background is darker (for want of a better word).
Bass takes on new detail, each vibration can be better felt.
There is a lot of extra tiny detail that I didnt know existed.
Like something brushing a string, the extra twang from a plucked string, the full extended ring of a cymbal strike, tiny effects/noises/accidents that werent resolvable before - even when there is lots of other sound going on.
The effect is quite subtle but very noticeable if you know well what you are listening to (bearing in mind this DAC was already extremely revealing so its not easy to get more from it!)
A new level of detail is brought to life.

The sound is slightly bright but they arent run in yet.
Since last week I'm also messing with some MOX resistors in my crossovers which are very revealing and brighter sounding, almost got the balance nailed.
These opamps are great so far, I'll wait about a week to see how everything beds in before fiddling further with the crossovers.


This is a good write up (by someone else) on many different Opamps tested on my DAC, you can get a good idea if any of these will be suitable for your own kit/soundcard.
http://www.enjoythemusic.com/magazine/equipment/1212/eastern_electric_minimax_dac_plus.htm


If you fancy trying them on your soundcard, DAC or CD player, the Dexas replace the following...
Single: NE5534 (as in my DAC), AD711, OPA604, OPA627 and others
Dual: NE5532 (as in my DAC), AD712, OPA 2604 and others





edit:
After the run in period, my hifi sounded cheap and nasty.
Bass was like a disco and while the detail was there, everything sounded the same volume level, as though it was compressed, all the finesse disappeared.
Swapping in/out the old opamps, the Dual Dexa opamps are overloading my DAC, as soon as they are in the system the sound is loud and compressed with no finesse.
Luckily the guy at Hificollective has let me return them without issue, thanks dude if you are reading this.

So my kit is now running with the single Dexa opamps and the original duals, it sounds great.
Lots of extra detail with all the finesse, just these are a worthy upgrade, saved me £93 as well lol.

 

Guys I ordered some opamps for my Xonar STX.
Opamps are LM6172IN and LME49720NA.
What do you think of using 2x LME49720NA as IV and LM6172IN as buffer ?
Headphones are Senns HD650.

 

The LME49720NA is the same chip as the stock LM4562NA in the buffer.
But yeah I've got 2xLME49720HA's in the IV and the improvement is great.

 

Thanks good to know I´m on a good path
Any suggestions for the buffer ?

 

Are you using the RCA ports on the soundcard? Because the buffer opamp isn't used for the headphones port.

 

Yes, when I switch to speakers (Monitor Audio Bronze BR2)

 

Hey rob mate what opamps would you recommend for Creative ZXR replacements.
i still have some of those from when i bought them from you last time lol for my Azuntech but they are probably not as good.

Quality is pretty sweet already on the ZXR so its probably going to cost quite a bit for better replacements.

As you know aswell the zxr card opamps must be low profile as in need to be able to put the shield back on it.

 

Check my review on this card, I mentioned a few opamps.

 

Hi,

Just popped in to thank you for your excellent review of the Zxr, though you could have mentionend what settings you were using during the games test. Another thing that would have been cool is if you had tested older EAX games with the Alchemy application.

Anyway, took your opamp suggestions to heart and ordered:
http://www.ebay.com/itm/170895883832?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1439.l2649
http://www.ebay.com/itm/171079253279?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1439.l2649

I really hope I'll be able to use the shield with those suckers. Oh well, at least it will be interesting to see how much the sound signature changes coupled with a pair of DT990 Pro.

 

No, you will not be able to use the sheild. IIRC, The opamps are too high.

 

Do you reckon it will have any real impact, not using the shield that is?

 

Nope.

 

Here's a link to my opamp mod.

http://www.sweclockers.com/galleri/11664-soundblaster-zxr-opamp-swap

 

I've tried to put a bit of EQ but I still gest a bit of analogue/harsh sound sadly.

I've also tried the foo_tube plugin but I don't like much the effect and I finally removed it.

Thanks anyways for the tips Tom, I hope I will find an happy end lol!

I've read your review Rob
What do you think about the Creative ZXR versus Essence STX or Titanium HD for HI-FI music reproduction?



My setup (Essence STX + studio monitor bookshelf) has still an anlogue/harsh setup but it has a good detail, transparency and focus over voices and instruments; I'd like only to be a bit more warmth and not fatiguing.

Actually I have 2x LME49720HA as I/V and a 2111kp as buffer; which op-amps could you advice me to use?

 

What's wrong with the standard ones? Keep in mind your opamps are probably contributing 1000x less distortion (probably more like 10000x) than the speakers / rest of the chain.

Changing any sufficiently high performance chip such as the ones on there for another of sufficient performance will cause no audible changes.

What speakers are they? Do you have a lot of hard surfaces near them?

Keep in mind that whatever you listen to will have been through 10s or even 100s of 'cheap' opamps like 5532s when it gets recorded / mixed / mastered before it even gets to you.

Optimising the setup of your system will make a much bigger difference. I garuntee it!

 

Hi again Tom, thanks for your reply

Well I find the stock op amps too much fatiguing and using now LME49720 and LME49860 the sound is a bit less fatiguing (but still harsh with female voices and some instruments like violin) but more transparent; I got also much more detail and focus.

The music flows from my asus essence stx through my m-audio studio monitor setup composed by BX8 D2 monitors (http://www.tnt-audio.com/casse/m_audio_bx8_d2_e.html) and SBX10 subwoofer monitor (http://www.bswusa.com/assets/product_images/large/maud_sbx10.jpg).


Which are your thoughts?

 

Sounds like a nice setup!

Fatigue with female voices and violin sounds like there's a lump in the response in the upper mid - could be a resonance in the bass driver?

http://forums.audioholics.com/forums/loudspeakers/72811-i-want-learn-about-cone-woofer-break-up.html

If so, it's difficult to do much about without fiddling with the crossover - but you could try sticking a notch on the EQ and see if you can tone it down?

In terms of opamps, I was using 49990s for a while but IMO a lot of these chips are way too fast for audio (49990 is 110MHz gbw...!) - if they're oscillating it can do all sorts of strange stuff to the output of the chip.

I firmly believe slower opamps are the way to go with audio, especially in a noisy environment like a PC. You're using chips with 55MHz gbw - still really fast. As a first step try something slower - I use 2132s / 2134s in select areas (phono stage, preamp, HF section of crossovers) and 5532s everywhere else.

So, you could try something slower (people seem to love the 2107 which is 4.5MHz gbw - still 100s of times faster than you need) and see if that does anything, other wise have a play with notching your eq and see if you can get rid of the fatigue issue

Edit: Obviously it'll sound weird having a notch in there, but it allows you to find the problem and solve it properly by other means. You could also try with a sine oscillator - you've found the resonance if the tone suddenly gets louder and sounds different.

 

The buffers would be your issue...the way I think of it, the I/V provides most of the sound quality but the buffers act as a bit of final "EQ"...so I would go with something with a bit more of a rolled off high end for the buffers.

Try swapping the opamps around, use the 49 for the I/V and use the 2111's for the buffers. That might give you a bit more of the sound you are looking for. Just to hold you over until you can figure out a better combination.
Good luck!
BTW, what other opamps do you have on hand?

 

The only way to EQ is with EQ. Opamps at audio frequencies will be completely flat - especially as buffers.

Have a look at figure 106 in the 49720 data sheet. Ruler flat to 7MHz. Woo, you rock, National!

You could put some passive EQ with an RC filter on the output - but the opamps won't do it (unless they're completely out of spec in which case distortion will be sky high).

 

I didn't say they perform EQ, I meant I sometimes view them in a similar way. I find it helps to explain their jobs in this way to people new to opamps and I/V and buffer circuitry.

I also notice that most opamps are very flat within the audio bands...but many opamps are known for their signature sound.

Make you wonder why people hear differences and have their favorites. Designers also have their favorites, units that produce a certain signature they are after. There is alot more to audio...over some graph.
There are many devices that measures great and sound awful and devices which measure not so hot and yet sound great. You cannot just rely on graphs, there is much more to the subject of audio circuits as I assume you already know.
Yes, I have seen the spec sheets for the 4562's also, I was using them in my circuits long before they started showing up on consumer sound cards. Yes National does rock.