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Old 11th May 2004, 10:44 AM   #21
mAJORD is offline mAJORD  Australia
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why dont you confuse me next time


i allready have 1 833 here, ill buy another and try it.

then try the OPAs and see if i can tell a difference.

I dont even know where to get OPAs from :/



Carlamart: its only an 24v24 supply, regardless. it simply wasnt enough gain and I couldnt achive anywhere near full power (20-25watt)
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Old 11th May 2004, 10:45 AM   #22
meo85 is offline meo85  Italy
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Quote:
Originally posted by carlosfm
You keep giving me ideas, Nuuk.

Oh, I can exchange my beautiful Ford Fiesta too.
Mercedes, BMW, anyone?
uhm, I've a Ford Fiesta too... then I can't help you
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Old 11th May 2004, 11:04 AM   #23
matjans is offline matjans  Netherlands
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in my experience you only need high quality opamps if gain >1. So if you are building a buffered pre with no gain (=1) opamp selection doen't matter that much.


When building an active crossover i couldn't distinguish between opa2132, ne5532 and a number of other, both high quality and crappy opamps.
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Old 11th May 2004, 02:27 PM   #24
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Quote:
Originally posted by mAJORD
why dont you confuse me next time

I dont even know where to get OPAs from :/

I have seen some postings before that implied that the OPA parts were harder to find and pricier in walk in in Australia for some reason. OPAxxxx are TI (Texas Instruments) parts.

ESP has them available. It is listed on there the price list page near the bottom.
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Old 11th May 2004, 02:48 PM   #25
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Quote:
Originally posted by carlosfm
moving_electron, don't take it personal.
OK

Quote:
[i]
The source is the most important component in a system.
Next to it is the preamp.
Treat it well, or it will screw the sound of your system.
[/B]
Agreed.

One thing that we should keep in mind though as far as recommendations on this forum is that many of these things are a matter of degree and there is always a dismissing return effect at play. You have communicated unambiguously that for the LM833 you think it is sort of a cliff and that it should never be used. So you have a yes/no recommendation on this. But bear with me as I try to make a general point.

In general I think that we have to keep in mind there are different budgets and different goals that exist and it is more useful to more people if the continuum of possibilities is presented. The price difference between nice sounding choices and high end parts will be fine for some and out of project $ goals for others.

So while "what is the best part" discussions are useful, hopefully we can agree that "here is a continuum of possibilities" discussions are very valid and valuable to a large number of people.

BTW: My opamps are properly bypassed, as is good practice.
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Old 11th May 2004, 04:24 PM   #26
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moving_electron,

There are high-end op-amps that are cheap.
OPA2604 and LM6172 are cheap and very good indeed.
Why use the much inferior LM833?

Are we talking cents here?
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Old 11th May 2004, 04:35 PM   #27
meo85 is offline meo85  Italy
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returning to the first topic of the thread, I keep on needing a schematic for my preamp with opa627... isn't there a link?? Is it something like this http://diyaudio.com/forums/showthrea...110#post197110 ?
Thanks, Matteo
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Old 11th May 2004, 05:09 PM   #28
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Quote:
Originally posted by carlosfm
moving_electron,

There are high-end op-amps that are cheap.
OPA2604 and LM6172 are cheap and very good indeed.
Why use the much inferior LM833?

Are we talking cents here?
In looking up prices it is interesting to see that the NE5532 price has dropped quite a bit over the last year I believe. So the NE5532 price is now nearly identical to the LM833 which based on your recommendation makes the NE5532 a better candidate on the low end on.

Prices seem to vary widely in different locals but from Digikey US prices (no tax) for small quantities of DIP parts:

OPA2604AP $4.28
LM6172 $3.80
OPA2134 $2.63
NE5532 $ .84
LM833 $ .78

Regarding the premium vs. non premium parts I think that it depends on budget. Sure for most people the ~ $7.00 price difference for a 2 chip preamp will not break the bank. It is only $7.00 and so it is not that costly to "upgrade". I think we can agree though that it is $7.00 that will not go elsewhere.

But consider an active crossover with baffle step correction and a notch filter etc and imagine that the number of op amps is 22. The cost to use the premium devices is ~ $77. Tax in many locals would raise this even higher. This may not be a consideration for you but may be a consideration for others. Perhaps the $70 allows for the purchase of much better tweeters and an upgrade to the midrange drivers on a speaker project etc.

Even on the preamp where the cost difference is much less the considerations may still be there for some. Maybe you were never a starving student, but I can remember trying to figure out how $40 was going to feed us for a few weeks. At that time the lower cost parts would have looked like a pretty good way to go in a preamp project.
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Old 11th May 2004, 08:45 PM   #29
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Quote:
But consider an active crossover with baffle step correction and a notch filter etc and imagine that the number of op amps is 22. [/B]
The best deal for crossovers until recently was to use quad chips, but nowadays there are less and less around. Good quality ones I mean.

In any case, you can see that Marchand has an improved version using better chips. OPA2134 if I am not wrong. And using several chips on a xover will also be a weak link if the chips are not that good.


Carlos
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Old 11th May 2004, 09:14 PM   #30
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.....could this design be adapted to became a preamp (less gain...right?)????


MINT

if you insist on using opa627's use this

adaptor

wouldnt it be nice...a battery powered, buffered, 627 and cheap! based preamp?

one more question, what would an apropiate gain for a gainclone for this example..


/just in case...i have no relation with any of the vendors.
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