The Opamp thread

[murrays]

Quote:

Originally Posted by diditmyself /img/forum/go_quote.gif I've never seen an adapter with shield. Opamps don't have ground pins. I guess you could connect a shield to one of the rails. Is this how it's done in the metal can opamps? I've just ordered some of those cheap SOIC to DIP adapters from Hong Kong. The traces are much shorter and look sturdier than Browndogs. If usual care is taken with decoupling caps as close to the power pins as possible, short feedback path, an input resistor and maybe an input filtering cap, I think you'll be fine. The use of an output resistor and/or a zobel network make the amp more stable driving capacitive loads. The use of a compensation cap when needed, or choosing "the right" value for feedback resistors also increase stability.

Yes, thanks. I have been working through a lot of those issues over the past few months with my amp. Bypass caps are soldered on the underside of the PCB, directly to the pins. Choosing the right input resistors definitely helped. Pretty much everything you mention has been done - and a few more. It helps having an old oscilloscope to hand to see if there's oscillations.

It goes against logic to get "a bad feeling" about the lack of shielding on the Browndogs when each extension cable to those discrete modules uses nearly a metre of wire.

 

[12Bass]

Quote:

Originally Posted by diditmyself /img/forum/go_quote.gif I've just ordered some of those cheap SOIC to DIP adapters from Hong Kong. The traces are much shorter and look sturdier than Browndogs.

Like this?

4 set SOIC to DIP 8-pin Convert PCB Adapter SMD OPA627 - eBay (item 230378690602 end time Nov-15-09 22:14:22 PST)

 

[leeperry]

Quote:

Originally Posted by murrays /img/forum/go_quote.gif It goes against logic to get "a bad feeling" about the lack of shielding on the Browndogs when each extension cable to those discrete modules uses nearly a metre of wire.

maybe because the HDAM are grounded and use caps to minimize oscillation? and maybe because the Earth also sounds amazing? besides I've ordered twice shorter leads, so I'm working on it ^^

pretty much each time I've tried browndog's, the sound has had distorted trebles to death. like OPA2132P that was sounding great, and OPA132U that was distorted and whiney

anyway, the last two IC op-amps I wanna try are LT1028 and LT1353...but having second thoughts, I will give up on those adapters...I'll use the DIP8 versions and try to find sturdier adapters than browndog's. DIP8 is good to fight EMI.

besides, the highest LT1028 grade is only available in DIP8.

 

[leeperry]

indeed these adapters look nice! I saw them on some asian site, but couldn't locate them for sale.

more explanations about their shielding: 10pcs Dual SOIC to DIP-8 Convert PCB Adapter SMD OPA627 - eBay

maybe the browdogs just suffer from poor design, after all

 

[igor0203]

Did somebody tried LT1816 or LT1819?

 

[ROBSCIX]

Quote:

Originally Posted by igor0203 /img/forum/go_quote.gif Did somebody tried LT1816 or LT1819?

Hmm, I don't remember any post in this thread about those units. Could be wrong did you do a search? LT doesn't really concentrate on the audio market and most of their opamps are meant for others tasks. You can get some that sound quite good but with others it is a bit of a crap shoot.

 

[igor0203]

I ordered each one from Farnell but was interested if somebody tested them. First I'll have to get few more SOIC to DIP8 adapter so I can test them.

 

[ROBSCIX]

Well post your impressions when you test them.

 

[igor0203]

Yes, sir!

 

[leeperry]

I didn't hear much difference while Earth was burning in, but I'll let Sun V2 burn in:



it's less tubey than Earth, but the bass is a bit shy to my taste

I love the crazy low end bass on the Earth

humm, the magic is gone I think...I'll put back the Earth later today, and I'm buying a burson from a friend...that should give

PS1: ah well...less tubey but less colored, I think 2*Sun>1*Earth will be neato.

I'm rearranging my box, I'll try to get rid of the extensions by using additional gold plated sockets as risers.

PS2: ahhhhhhh the alternative takes on the 24/96 DVD-A of "In the Court of The Crimson King" really sound amazing right now...if only that doofus would stop playing flute in my room right next to me

and BTW, anyone knows where to buy some AD797BN

apparently the whole AD797B line has been phased out :/

 

[SpudHarris]

I'm told that the ada4627-1 is the next big thing...... Anyone tried them? I can't get them here in the UK, do AD offer samples

 

[leeperry]

well, LT1364 gives a magic touch to vocals but it basically mono-izes them to death..2*LT1363 on adapters was a far cry as far as stereo separation was concerned.

2*Sun>1*Earth is true dual mono from A to Z, amazing!



and putting additional sockets as risers is just not manageable:

 

[ROBSCIX]

Quote:

Originally Posted by SpudHarris /img/forum/go_quote.gif I'm told that the ada4627-1 is the next big thing...... Anyone tried them? I can't get them here in the UK, do AD offer samples

I haven't tried them yet but I think I heard these mentioned by others. I will have to get some and try them out. Thx for the heads up.

 

[ecclesand]

Quote:

Originally Posted by SpudHarris /img/forum/go_quote.gif I'm told that the ada4627-1 is the next big thing...... Anyone tried them? I can't get them here in the UK, do AD offer samples

Quote:

Originally Posted by ROBSCIX /img/forum/go_quote.gif I haven't tried them yet but I think I heard these mentioned by others. I will have to get some and try them out. Thx for the heads up.

I ordered a couple. They are not cheap!

 

[SpudHarris]

Where did you get them Doug? any chance of getting me a couple? I can get them through Farnell but it's US stock with like a $30 surcharge :^(