[ph0n6]

Just finished my review of the V5i, overall quite a good opamp: http://www.head-fi.org/products/burson-audio-supreme-sound-opamp-v5i/reviews/17179

 

[raoultrifan]

Very nice review, thanks!
 
I've finished my tests and review with the V5i too, so for those interested in how V5i sounds in Low Pass and Voltage Amplification stages please have a read here: http://www.head-fi.org/t/784790/burson-supreme-sound-audio-v5-opa-d-v5-opa-s-review/120#post_12959395.

 

[igytech]

Can some one who use them compare OPA2227PA, LME49860NA and muses8920

 

[raoultrifan]

MUSES8920 is a FET-input opamp and may work different than the other 2, most likely in I/V stage could be better, after all it was designed to be used in I/V stage.

For low-pass and voltage-gain I would incline to OPA2227. To be honest, I'm not OK with the background of 49860 opamp when used in voltage-gain.

For buffer/output stage you could try any of them, just be sure will not oscillate.

 

[vapman]

Just replaced my portable amp (bMac 3CH MK2) Output Buffer Op-Amp JRC4556 with Burr Brown OPA2132PA. Right away noticing better soundstage, slightly recessed mids, and slightly brighter treble extension. will have to try OPA2132PA in place of the Gain Op-Amp NE5532, too.
 
 
 
 
Would MUSES8920 be a good replacement for the gain op amp, and OPA2132 to output buffer?

 

[adydula]

 
Hey Guys,
 
I was asked this question several post back and I got a reply from one of the actual TI Audio Engineers that is involved with this and other of the new TI op amps...feel free to contact him at DIYAUDIO.COM he is a wealth of technical information. 
 
he is: johnc124

1. Occupation
   Electrical Engineer: Precision analog semiconductor applications and new product definition
   
   Country
   United States
   
2. Signature New Product Definition - Texas Instruments Precision Analog / Audio Products
   

 
 

Originally Posted by adydula  Hey guys I got this question over at another forum: I really like your mod, but I'm worried about how the OPA1688 will handle output power under 32 ohms or even lower impedance headphones, because despite having the same mA output I see from the datasheet that can only handle 50mW/32ohms before clipping; for 2 paralleled opamp this would be 100mW/32ohms, so about 6 times less power than original 4556 opamps (please correct me if I'm wrong). I will most likely purchase a couple of OPA1688 opamps soon, because I'm very interested in final results, but meanwhile do you think you could please test output power of your modded O2 with OPA1688 as output buffer for 32ohms output resistance? Also, if you could somehow measure OPA1688 die temperature while doing this test it would be perfect. I only have used my 250 ohm T90's so far, I will try with lower impedance headphones and a thermocouple today. Ideas?? Alex

Remember that power is current squared times resistance. The OPA1688 clips into 32 ohm loads when it hits its internal current limiting circuitry. 1 channel of an OPA1688 (1/2 the chip) will deliver 50mW into a 32 ohm load without clipping, which is about 40mArms. If you put both channels on the chip in parallel, the output current available doubles to 80mArms, which is ~205mW. 2 OPA1688 chips, with all 4 amplifiers in parallel would be 40mArms x 4 = 160mArms or 819.2mW.
__________________
New Product Definition - Texas Instruments Precision Analog / Audio Products

 

[raoultrifan]

  Just replaced my portable amp (bMac 3CH MK2) Output Buffer Op-Amp JRC4556 with Burr Brown OPA2132PA. Right away noticing better soundstage, slightly recessed mids, and slightly brighter treble extension. will have to try OPA2132PA in place of the Gain Op-Amp NE5532, too.
 
 
 
 
Would MUSES8920 be a good replacement for the gain op amp, and OPA2132 to output buffer?

 
Well, I'm not sure OPA2132 was designed to be used as output buffers directly connected to headphones, though I don't know bMac's internal schematic. Technically speaking JRC4556 might be safer as output buffer I'd say. I would choose the OPA2132 for the gain stage instead, it has been proved it sounds very well in several headamps. MUSES8920 and also MUSES8820 should sound very well too in gain stage and their internal noise is lower then the NE5532, so feel free to give'em a try.

 

[vapman]

   
Well, I'm not sure OPA2132 was designed to be used as output buffers directly connected to headphones, though I don't know bMac's internal schematic. Technically speaking JRC4556 might be safer as output buffer I'd say. I would choose the OPA2132 for the gain stage instead, it has been proved it sounds very well in several headamps. MUSES8920 and also MUSES8820 should sound very well too in gain stage and their internal noise is lower then the NE5532, so feel free to give'em a try.

Darn I need to stop writing posts before going to bed.
You are right and the photo I posted showed my post you quoted was mixed up. The 2132 is in the gain stage in fact.
 

 

[vapman]

Sorry for a double post, but I'm looking at MUSES8820 opamps on eBay, and wondering if all the ones in China for under $20 shipped are fake or not?

 

[raoultrifan]

I suggest Mouser or similar stores for MUSES 8820 and you can also find OPA1688 and adapters for them, in case you feel like upgrading the output buffers (more about this http://www.head-fi.org/t/616331/o2-amp-odac/5205#post_12947025 

 

[vapman]

  I suggest Mouser or similar stores for MUSES 8820 and you van also find OPA1688 and adapters for them, in case you feel like upgrading the output buffers (more about thjis http://www.head-fi.org/t/616331/o2-amp-odac/5205#post_12947025 

Thanks a ton man, was just looking for more info on different output buffers, as I've only been messing with the gain stage so far. I have been checking out Mouser and Digikey and will probably use one of them soon to get a legitimate MUSES IC. Thanks so much!
 
I would get a burson IC opamp but there is no way I could fit one of those in my tiny portable amp... however, I have room in my Technics stereo...

 

[raoultrifan]

I'm glad I could help. Anyway, the SS V5i might fit after all, try measuring the space from inside your amp and compare with V5i dimensions.
 
Good luck!

 

[dukefx]

Use 13x13mm as measurement (as opposed to 11x11mm listed on the datasheet). When I measured mine I should have had 1mm left between the V5i and the nearest capacitor. In reality the V5i is pushing the cap away and barely fits.

 

[RyokoZekem]

I am using the LT1364 in my Little Dot i+ amp and its getting super hot. I am worried it will burn out early but would running it cooler with say a tiny heatsink and I do have a few, cause problems in the way it processes sound? Does an OPAMP running warm/hot cause different sound characteristics?

 

[raoultrifan]

Well, you're replacing a 16MHz-7V/uS opamp with a 70MHz-1000V/uS one, so it might oscillate, despite the recommendations from http://www.littledot.net/forum/viewtopic.php?t=385 for the LT1364 I strongly suggest you to get a scope and check for oscillations. Also, MC33078 has a max. recommended voltage of 36V (+/-18V) and LT1364 has only 30V (+/-15V), so it might worth checking the actual voltage on the opamp rails, just to be sure you're in the safe zone with the LT1364.
 
You can also try the BURSON SS V5i that can tolerate even +/-16V, it was specifically designed for music and it also has a metallic case for a better shielding and thermal transfer, but also MUSES8820 or the more expensive MUSES02 might be a good upgrade for the MC33078.
 
Please, do understand that the sound gets created inside this opamp which is named Voltage Gain or Voltage Amplification Stage and all the micro-details and soundstage get created in here. The final tubes are the buffers that takes care of final warmth and final character of the sound and also handling the distortions very well. Using an opamp dedicated for music will give you a very high probability to get a very good sound without being worried of oscillations or heat issues (at least in most cases).
 
Good luck!