[Duncan]

Hi all

Here is a list of op-amps that I can pick up... I'm just wondering if there are any you would advise me getting, or NOT getting as the case may be to try in place of the AD823?

This is the 9v version of the Meta that i'm using if that makes any difference???

(I'm guessing, somewhat naively that the bottom chip, the AD8534AN will be a good match...)

 

[JMT]

Duncan

Check out Tangent's Guide to Audio Op-Amps, he has done some extensive researching and testing of various ones. Also, when you decide, contact me.

 

[andrzejpw]

Duncan:

Check out the AD8610/8620. Supposedly, its a great opamp for the meta42. It seems like a lot of people are using it, and are amazed. I'll let you know next week.

Also, check out the AD843.

 

[Gariver]

Tangent's Single to Dual Opamp Adapter allows you to use two (2) single opamps in your dual opamp socket. These adapters open up your possibilities! For example, you can use two OPA627s, OPA637s, or two AD845s in your dual opamp socket.

Without this adapter, you can only use dual opamps in your META42. That sure limits your choices.

Single to Dual Opamp Adapter
Take a look...
http://www.tangentsoft.net/audio/opamp-adapter.html

I liked the idea of having NO LIMITS in terms of opamps. So I bought two from Tangent. Prices? The adapters are reasonably priced considering the labor involved. So check it out!!!

 

[morsel]

That is the most horribly scary and inappropriate list of opamps I have seen in a long while. Run screaming in terror from that vendor.

Not only does Tangent have a good guide to opamps, but he has plenty of opamps in stock. Alternatively you can buy direct from Analog Devices from their web page, but I bet shipping from Tangent will be slightly cheaper. Don't forget there are also the BrownDog adapters for single and dual SO8 surface mount opamps.

 

[Duncan]

Thanks for the tips guys...

I'm not sure which direction I'm going to go in... but, I can't actually damage the rest of the amplifier by putting in an incorrect chip can I? (boy, am I naive

)

JMT, I'll let you know what my thoughts are after I get an answer to this question

 

[JMT]

Based on my ears, here is my list in order of preference:

1. Dual AD843KNs
2. Dual AD8610s
3. Single AD8620[/list=1]
   For all of the above, you will need some sort of adapter to fit into the DIP socket. I also have some AD843JN's on order. Supposedly a cut above the 843KNs.

 

[Gariver]

The only way to really screw up an opamp is to plug it in backwards. Otherwise, few problems arise. However, it's always a good idea to check the pin-outs of the opamp you are using.

I'm giving you the net-addresses of TI Burr Brown and Analog Devices. I believe that 95% of the META42s will use opamps by these two manufacturers. Just plug in the opamp number in the search boxes to get the info...

Check TI Burr Brown opamps here...
http://focus.ti.com/docs/analog/analoghomepage.jhtml

Check Analog Devices opamps here...
http://www.analog.com

I have to agree with Morsel: That Maplin list is NOT too hot! Get another opamp list. Go for TI-BB or AD opamps (RS Components)! In this respect, don't forget to read that Tangent link that JMT gave you. It's an excellent starting point in choosing opamps.

Once again: Congratulations to all the people that created the META42, esp Tangent for the work at his site. It's a great little amp!

 

[andrzejpw]

Quote:

Originally posted by JMT Based on my ears, here is my list in order of preference: Dual AD843KNs Dual AD8610s Single AD8620[/list=1] For all of the above, you will need some sort of adapter to fit into the DIP socket. I also have some AD843JN's on order. Supposedly a cut above the 843KNs.

1. 
   
   
   Hi!
   
   Can you give us some words on the difference between the 843 and the 8610? Is it a large difference? Is it worth it to go with the 843 even though I have the 8610?

 

[Duncan]

Throwing things wildly off topic momentarily...

I was searching for a reference to the AD8620 with MSN search and came up with this

Aren't search engines done on a popularity basis? - If so, its pretty darned cool that our little home here is so well searched for

Back on topic...

Gariver, I think i'll heed your advice, and take a look at RS Components site, I very much doubt that any of the US providers would want to waste the time and effort of sending a $2 op-amp across the atlantic...

 

[AngusMcToon]

This might be a ludicrous question (by a non-DIYer mind you), but just out of curiosity, would it be even theoretically possible to have a Meta42 that switched between different opamps, that allowed you for example to install 3 different sets and switch among them? Then you could say, e.g., o well, I like the Burr Brown sound on Beethoven quartets, but the AD843 for rock and roll?

(I imagine though that practically you probably model the rest of the amp's components based on the amp choice right? So it would be more like building 3 complete amps within some roomy case...and then why not just have 3?)

 

[Toe]

Quote:

Originally posted by AngusMcToon This might be a ludicrous question (by a non-DIYer mind you), but just out of curiosity, would it be even theoretically possible to have a Meta42 that switched between different opamps, that allowed you for example to install 3 different sets and switch among them? Then you could say, e.g., o well, I like the Burr Brown sound on Beethoven quartets, but the AD843 for rock and roll? (I imagine though that practically you probably model the rest of the amp's components based on the amp choice right? So it would be more like building 3 complete amps within some roomy case...and then why not just have 3?)

Actually, I've been considering building an opamp switcher for testing purposes, but the only way you could do this with a META42 PCB would be with some kind of add-on board with the switch and opamps built onto it.

 

[andrzejpw]

I had the same thought. But would it be affected a lot, I mean, if you just ran 8 wire. . .

 

[tangent]

Quote:

This is the 9v version of the Meta that i'm using if that makes any difference???

Yes, it does make a big difference. That's one of the reasons my reviews concentrate so much on minimum voltages: if you drop below them, you risk bad sound. When reading those reviews, though, beware that I'm doing a nasty torture test on these chips. With good headphones, good recordings and buffering (as in the META42) you can get all of these chips to sound better at lower supply voltages. Case in point, I say the AD845 needs something like 8V on that page, but in practice in my system, I was able to run the battery down to about 6V before hearing intolerable amounts of distortion.

All that having been said, I don't think the AD8610/20 is a good match for a single 9V amp. It might _run_ from a single 9V battery, but not well or long. And, the AD843 won't run at all from a 9V battery. My personal high-end chip of choice for 9V supplies is the AD845. I'm warming to the AD8512, but I need to do more testing before I come out and embrace it wholeheartedly.

Quote:

I can't actually damage the rest of the amplifier by putting in an incorrect chip can I?

No, it will just work or it won't. If it sounds bad, add a second 9V battery in series with the first, and if it fixes the problem, you know the chip simply requires more voltage. If that doesn't fix the problem, something else is going wrong, because all chips I've used that are suitable for audiophile use will run just fine from 18V.

Quote:

would it be even theoretically possible to have a Meta42 that switched between different opamps, that allowed you for example to install 3 different sets and switch among them

This would be difficult to do well. One problem is keeping the switch cost and switching complexity low. To do this, you would need to keep all of the chips working all the time -- all chips powered and amplifying the same input signal all the time. Then you would simply switch among the chips' outputs. This would require a DP3T switch, which is probably only available in rotary styles. This would be big, and it would be an extra set of contacts in the signal path.

 

[Gariver]

No big deal, but...

AD8610s are single opamps.
AD8620s are dual opamps.

JMT was most likely in a rush.