OpAmps and specs vs preference

[chrism]

Thanks Peter.

Anyone had a go with the AD826 yet. Be interested in any comparison to the LME49720HA as that's what I have currently in the Caiman.

Regards

Chris

[StanleyB]

I have just discovered a hidden gem from the same AD826 stable. It's the LMH6655. The only snags are:
1. It is a surface mount type, so needs to be fitted to an adapter. Tirna Electronics assembled a few for me and their workmanship is fantastic.
2. The max voltage is 12V. So it can only be used in the TC-7520 or in the line output of the Caiman.

Spec wise it is a close match to the AD826, but has an even lower noise voltage. Price wise it is far cheaper by a mile.

Initial listening test compared to the AD826:
Deeper bass.
Less metallic artefacts in the tops.

It sounds better than the THS4032, at about 20% of the price.

Well worth adding to any opamp collection, especially if you are a bass head. Scores highly on reggae.

[Peter Galbavy]

Not one I saw, but then I pretty much ignored all surface mount only opamps in my initial sweep.

Back to the spec vs preference stuff, I have not got my complete stable after FedEx finally delivered the samples that TI sent me weeks ago (they are crap, FedEx, aren't they ?). I will be building a basic spreadsheets with a column for each of the published specs and then some further "subjective" comments columns and I will see where I get over the coming weeks. I have an initial playlist and I will try to work through it a number of times before moving on the the next opamp. I will happily share my results here later for others to update / edit with their own.

[Peter Galbavy]

Attached is my first pass of all the opamps I have "collected" and some basic specs. Upon first inspection - and the point of this exercise is to hypothesise over which specs are useful - the OPA2228 is actually the closest to the shipped LM4562. Similarly, if the AD826 is your drug of choise then the AD828 is "better" is almost every published spec.

Please jump in and tell me what other data to collect (as a mechanical exercise) including trying to normalise some of the specs to particular arbitrary values, like 15V supply and/or 1KHz frequencies. I intend to add columns for subjective comments on performance - opinions very much welcomed.

I have not yet even opened my Caiman to try these. That's the plan for this afternoon

[StanleyB]

Great work Peter. But careful with the predicted thunderstorm later today. If it does materialize, best keep the Caiman closed. Stormy weather can create a high static electricity content in the air.

[Alex Nikitin]

Similarly, if the AD826 is your drug of choise then the AD828 is "better" is almost every published spec.

Peter,

AD826 and AD828 are essentially the same chip, however AD826 is unity gain stable and AD828 is only stable for gains +2/-1 or higher. For that reason AD828 can not be used as a universal drop-in replacement for unity gain stable opamps.

Cheers

Alex

[Peter Galbavy]

Thanks for that - now which bit of the spec tell me that so I can express that on the spread sheet ?

[Alex Nikitin]

Thanks for that - now which bit of the spec tell me that so I can express that on the spread sheet ?

For AD828 it is in the general description section of the datasheet. Sometimes it is in the AC parameters table as a "minimum stable gain" or something similar.

Cheers

Alex

[Peter Galbavy]

Thanks!