I can give you and anyone who might be looking at this thread a negative advise: don't use a TLE2071 (which isn't from Analog Devices anyway). Its supply current increases a lot when it clips against the negative rail, which could lead to weird behaviour with the QUAD 405's Zener diode supply.
Rather than just rolling op-amps, read Keith Snook's extensive experience with improving the 405. I think you'll see differently about their importance or otherwise to this oddball design and of course, sounding different implies many more possibilities than making real improvements. ~ QUAD 405 Amplifier Information and Modification ~
I think AD discontinued audio op amps line/development. I would not go for a specific brand but try a few brands and types and see what you like. AD797 is a very good one but is a bit bright sounding for whatever reason, while OPA134s are much more 'relaxed'. OPA 604 is very bright for some reason, OPA 627 is close to OPA 134 but dark sounding. AD834 is also a fast op amp . I would expect a brighter sound. I believe the newest audo op amps are the texas soundplus OPAxxxxs.
fun readingL Audio Reviews: Flavors of Audio Op-Amps
fun readingL Audio Reviews: Flavors of Audio Op-Amps
Do you have the means to determine that whatever op amp you select is properly working in your application? For example, the AD797 is a high performance part that has to be applied properly to perform at its best. One has to be careful regarding oscillation, supply bypassing, careful selection of surrounding passive parts impedances, etc. The highest performing parts are not often general purpose drop-in parts suitable for op amp rolling.
Good luck.
mlloyd1
Good luck.
mlloyd1
That is a good point and yes have to make sure the quescient current of the opamp plus the current needed for stable zener voltage does not exceed about 10mAs or so defined by the resistor in series from +. Also prefer opamp with bandwith low so no high frequency oscillation or instabilities occur. A 100nf ceramic cap at the op amp pins is highly recommended. it looks that OPA134 and AD979 are farily good replacements, OPA627 and AD834 are more current hungry and prone to oscillation due to higher bandwidth. As far as I heard and tried though these are all suitable for rolling without changing anything else in the circuit. but they tend to sound brighter. Nevertheless I settled on the OPA134 for upgrade work. NE5534 and TL071(was used in quad405s at some time originally) are suitable but somehow they sound very flat.
the AD843 is a very fast op amp designed for high frequency applications. its bandwith is 34MHz and fast slew rate - these can cause high frequency oscillations that are outside of the hearing range but affect the circuits operations in. It does need higher current that the quad is designed to provide to the op amp in the circuit so
have to change a couple of resistors. https://www.analog.com/media/en/technical-documentation/data-sheets/AD843.pdf So i would stay with AD797 if you really want to move to an AD device. However you never know until you try the AD834 as is.
I suggest you give a try other than AD products too. also make sure you buy from reputable distributors to avoid a fake.
have to change a couple of resistors. https://www.analog.com/media/en/technical-documentation/data-sheets/AD843.pdf So i would stay with AD797 if you really want to move to an AD device. However you never know until you try the AD834 as is.
I suggest you give a try other than AD products too. also make sure you buy from reputable distributors to avoid a fake.
You wrote "They should be..." and not: They are...
Mark, nearly all of your comments prove that maybe either your hearing is mediocre or you don't have quality devices to discover the differences between devices mentioned in the actual thread you comment in.Whether it's a diode or an operational amplifier, your comment will be like that: There should be no audible difference between good (opamps / diodes / etc.). But there is a difference.
Ensure calm environment, get enough rest, train your ear, listen to quality music.
Find me a man who hands out certainty like it's candy, and you can be quite certain that you have found a fool.
When a member with an actual EE background is devoting their time to this forum, a little more gratitude would not go amiss. Don't be an insufferable golden-eared audiophool snob.
When a member with an actual EE background is devoting their time to this forum, a little more gratitude would not go amiss. Don't be an insufferable golden-eared audiophool snob.
You mean 4500+ posts from Mark in 3 and a half years?Thanks!
I have enough background and measurement instruments to not feel myself an audiophool. Able to measure devices down to 2ppm THD (totally unnecessary anyway) and have at least 20000+ hours listening and amplifier modifying experience since 2004.Mark often questions indirectly the listening experiences of others here at diyAudio, so let Martin Mallison from ESS answer. He's talking about development of Sabre DACs:
23:22 Martin Mallison, CTO, ESS
"...and we find that what happens is..." ... "You only make a sale when finally get the audiophile guy from that company to come and listen..." ... "The engineers say OK, but that won't do..."
25:21 Martin Mallison, CTO, ESS
"You can still find certain human beings..." -- So not all humans can achieve this level of hearing. It's interesting, that your hearing hairs has muscles. The brain actively feedback and moves (tuning) the resonators.
29:15 Martin Mallison, CTO, ESS
Hope now you understand, my comment was not pejorative nor derogative. It was realist.
Last edited:
In thread https://www.diyaudio.com/forums/parts/378585-manganin-wire-wound-resistor-diy.html#post6826226 I've found these:
Cagomat's experince:
"I build my own manganin wire resistors used on cathode in a tube preamp. Bifilar wound. They sound better than anything I used before. The only resistor bettered this resistor are the new Audio Note niobium resistor in 2W version"
Mark's theory:
"any difference between different metals in linearity is probably sub 1 ppm, so no they do not sound better, you imagine they sound better via expectation bias!" - Written with an exclamation point. If you would not understand who is the (theoretical) king here.
Should be: "... so no they probably do not sound better..." ... "you probably imagine they sound better via expectation bias."
So yes, "Find me a man who hands out certainty like it's candy, and you can be quite certain that you have found a fool."
Cagomat's experince:
"I build my own manganin wire resistors used on cathode in a tube preamp. Bifilar wound. They sound better than anything I used before. The only resistor bettered this resistor are the new Audio Note niobium resistor in 2W version"
Mark's theory:
"any difference between different metals in linearity is probably sub 1 ppm, so no they do not sound better, you imagine they sound better via expectation bias!" - Written with an exclamation point. If you would not understand who is the (theoretical) king here.
Should be: "... so no they probably do not sound better..." ... "you probably imagine they sound better via expectation bias."
So yes, "Find me a man who hands out certainty like it's candy, and you can be quite certain that you have found a fool."