AD-8620 is here and sounding Wounderfull
Jun 12, 2002 at 8:32 AM Thread Starter Post #1 of 10

ppl

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Well for alot of us head-fiers the long awaited dual version of Analog devices AD-8610. Well afteer mounths of antisipation ti is available see at http://products.analog.com/products/...product=AD8620 As soon as i got ahold of $ of these I imeditly installed one in a SOIC to DIP Adaptor socket and fitted the AD-8620 that used to Employ an AD-746 with an AD-823 prior to that. Well the current Drain of my Pocket amp went down from 15 Ma to 11.1 from the 746 to the 8620 infact the AD-824 Pulled 13.26 Mill's from the series connecten 9 v's. see my post in the AD-8512 Review.

THE SOUND , well its extreamly close to the Single AD-8610. Thei mprovement over the 746 was quite noticable. First was about what appeared to be about an octave of bass extention. this made the Parralell pair of EL-2001 buffers really come alive. and this was with out the midbass Presesnce of The 823 In fact the 8610/8620 are the most naturel sounding mid-bass and silky sooth midrange i have heard from an opamp.Most all opamps eather roll off the last 10-20K octave and or add a upper midrange presence in the3-7KHz. range. These analog Device opam's are compleatly devoid of this nasty quality that seem to be Be present in lessor Opamps. The 10-20K range on the 8610/20's is crystal cleen and Hightly detailed with plenty of rendition of upper harmonic detail to Flute and other high pitched wind insterments. Strings are reproduced with quick articulation that is quite plesent to listen to. the total lack of grain is so refreshing once it is no longer present. these devices have fooled some seasoned listeners into thinking that thay were listen to a discrete component and were embarresed to find a lowy Opamp and to pour salt into the wound a IC output stage to boot.

The AD8620 leaves all other Dual opamps in the dust Musicaly the soundstage is Better than the 823 of whitch i allready thought soundstage was it's halmark. Another most instantly noticed quality of the 8620 was the compleatly silent background the musical transients blend into, Now i am not talking noise but however refering to the Tendicy of almost all other opamps to blur transients to the point of not obtaining complete silence befor the next transient arrives. In terms of sound quality it is so close to the 8610 single that most listeners would be hard pressed to here any difference.

in conclusion This dual opamp will operate quite well on the battery voltages most DIYers use a pare of 9 volts almost perfect for it's +/- 13 Volt Supply Limit. these opamps are incredibly stable more-so than any of the A- 823,8512,746,OPA-627,2107,132.

My pick for opamps's of the year award This pair of recent Opamps from Analog devices is so far ahead of what has been available as to redefine the Benchmark for Audio Opamp's
 
Jun 12, 2002 at 11:13 PM Post #4 of 10

morsel

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The cost is about the same, the offset voltage is ever so slightly better, and there is no thermal coupling between stages, but that should not be an issue if you are buffering your opamps. The bottom line is it should not matter.
 
Jun 18, 2002 at 11:33 AM Post #6 of 10

adewolf

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PPL, I need your advice
redface.gif


A pair of AD8620 arrived at home today, and some AD8610's are on the way.
I really want to test this op-amp since, from your tests and opinions, they seem the very best op-amp's around.

Two questions:
1. Can I connect the AD8610 to my meier's HA-1 just changing my actual power supply (+/- 15V) to +/- 12V?
I'm also going to use one AD8610 in the META42 as soon as I can get them (the META and the AD8610).
2. Can I use the ad8620 within my Hansen-Cmoy? (with two 9V).

Please, reply (and, please, asume that my knowledge on electronics is very poor).
 
Jun 18, 2002 at 10:33 PM Post #7 of 10

jmedin

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Hey PPL, how much current are you running in the outputs of the 8620? (b4 the 2001's and what is the value of the series iso-resistor?)

What mode (if any) of current injection are you using (Xistor Types?), series resistor/Cascode isolation resistor?

Thanks!

Jeff
 
Jun 19, 2002 at 6:19 AM Post #8 of 10

ppl

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The ADS-8620 is a dual opamp and the AD-8610 the Single. The META uses the Dual so the AD-8620 mounted in an SOIC to Dip adaptor will work. Yes the AD-8620 will work in a cmoy but i would use the single AD-8610 since the Small SOIC cannot disipate the power of the Dip. The battery life will improve because of the lower operating curent of the 8610/8620 vs the OPA-132/2132. I use a 0.78 Ma Casscode current source on these opamps and thay drive the inputs of buffers.

As far as using these in jan's Amp I think you can providing the lower Supply voltages will not affect the Operation of the Output strage. I would consult jan on this.

I used 0.1uF/160 volt wima decoupling caps on the Board but none on the adaptor.
 
Jun 19, 2002 at 6:56 PM Post #9 of 10

tangent

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Quote:

Can I connect the AD8610 to my meier's HA-1 just changing my actual power supply (+/- 15V) to +/- 12V?


There was a recent post about using 627s in an HA-1 where Jan Meier said his board design makes a few assumptions about the pinout of the chip. Pins 1, 5 and 8 on the LM6171 have no connections to the chip inside, and these are connected to a power rail in the HA-1, IIRC.

In the 8610, two of these pins are marked NULL, which means they're for adjusting the DC offset on the output of the chip. More than likely, you don't want those connected to a power rail. (!) I suppose you could clip these pins off of the SO-8 to DIP-8 adapter to avoid the problem....
 
Jun 20, 2002 at 6:43 AM Post #10 of 10

adewolf

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Hi Tangent!
It was I who posted about at Headwize.
What Jan pointed me was that: the LM6171' pins 1, 5 and 8 not connected at all; but AD8610' pin 1 and 5 can be used to control output offset so, if I want to use this possibility they have to be connected and, then, I shuold need to make some changes in the layout and pcb desing.
As I'm not using those pins, I have not made any change appart from what Jan and ppl suggested, (to change the kOhm in the resistors that connect power rails to the opa' outputs).
 

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