CD player upgrade

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Stolle
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CD player upgrade

Post napisao Stolle » 22 svi 2010, 22:07

Tema o ovome ima bezbroj na netu, mnogo rasprava, sukoba, šta je bolje, ovo ili ono, ovako ili onako i tome kraja nema.
Jedino što je sigurno, zvuk se može mnogo poboljšati, često i ne košta mnogo a satisfakciji nema kraja. Malo eksperimentisanja će dovesti do toga da svako pronađe ono što mu odgovara.
Sve što je u CD playeru se može poboljšati. Od kućišta, napajanja, DA convertera, audio izlaza...Toliko toga ima, da se čoveku zavrti u glavi. Ja sam nešto od toga radio, ne mnogo i ne u previše detalja i rezultati su bili više nego dobri. Naravno, ima ljudi koji su ušli u srž tog problema, poznaju najbolje modele CD playera, koji su najbolji za upgrade, izmene sve što je bitno za određeni uređaj i on već spada u uređaj nekoliko klasa naviše što po kvalitetu, što po ceni.
Ja nisam neki extra expert u tome, ali napisaću ponešto što sam radio, a sigurno će neko dodati još toga.
"29 poslednjih dana u mesecu je najteže"

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Re: CD player upgrade

Post napisao Stolle » 22 svi 2010, 22:33

Najpre mreža.
Diode u grecu treba zameniti brzim. Elektrolite zameniti nekim kvalitetnijim, ima i onih for audio, ali su preskupi, pa ko može... Kapacitet elektrolita u filtraciji sam povećavao, negde duplo, negde i više puta.
To je ono osnovno, a ima se toga još mnogo raditi.
Izlaz.
To su uglavnom operacioni pojačivači i tu su stavljani prilično jeftini OP, čak i u skupim uređajima. Najbolje OP imaju AD (Analog Devices) i BB (Burr-Brown). Posle ću postaviti neka mišljenja i ocene, koliko koštaju, kako zvuče...
Znači skinuti operacione pojačivače i staviti podnožja (profi) zbog lakšeg testiranja različitih OP.
Na ± napajanju OP dobro je staviti polipropilen smd blokove 100nF do 220nF što je moguće bliže pinovima OP.
Najbolje je izdvojiti napajanje audio dela, odnosno napraviti poseban stabilisani ispravljač ± napona i to sa tranzistorima, ne tipa 78xx, 79xx. Na kapacitet elektrolita ne treba žaliti.
Ako u izlazu ima sprežnih kondenzatora, bilo bi dobro zameniti ih što kvalitetnijim blokovima (za audio) i tu koliko se može, ne treba štedeti. Mundorf su kao dobar izbor, kvalitet-cena.
"29 poslednjih dana u mesecu je najteže"

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Re: CD player upgrade

Post napisao Stolle » 22 svi 2010, 22:41

I sad OP:
Analog Devices AD744 Cost, single: $4.52 Vmin, 0.5V into 33 Ω: 6.8V
Cost, dual: n/a Vmin, 2.0V into 330 Ω: 9.2V


Full review to come later.
Analog Devices AD823 Cost, single: n/a Vmin, 0.5V into 33 Ω: 4.3V
Cost, dual: $5.00 Vmin, 2.0V into 330 Ω: 6.1V


Spec-wise, this chip is somewhere in between the OPA134/132 and the OPA604, with one notable exception: it will tolerate single-supply operation down to 3V. It's also a "rail-to-rail" design, which ideally means it doesn't have any headroom requirements between the supply voltage and the output voltage. In practice, output loading and other things mean a practical chip can't go quite to the rails. This chip does a lot better than any of the above chips, at any rate. This makes the AD823 ideal for battery-driven amps.

Sonically, this chip is slightly more impactful than the OPA134/132 in the bass area, and rather more detailed. With aggressive-sounding headphones, this chip will probably sound too aggressive, unless other parts of the system compensate for it.

The main disadvantage of this chip is that it has a much lower output current than is typical: 15mA for the AD823 vs. around 40mA for most op-amps. While few headphones actually require more than 15mA of continuous current, all headphones seem to perform better when given a "reserve" of current far above their nominal requirements. I suspect it has to do with how much you make the amplifier strain, which affects its performance. This chip will perform adequately even with low-impedance headphones, but suboptimally. Output current isn't a consideration at all in buffered headphone amps, of course.

Bottom Line: Seriously consider this chip over the OPA132/134. Especially consider it it you aren't happy with the laid-back Burr-Brown sound and don't mind spending a bit more on the chip.



headwize.com/ubb/showpage5.php?fnum=3&tid=2374
Analog Devices AD825 Cost, single: $3.76 Vmin, 0.5V into 33 Ω: 4.7V
Cost, dual: n/a Vmin, 2.0V into 330 Ω: 8.6V


Full review to come later.
Analog Devices AD843 Cost, single: $8.56 (AD843JN) Vmin, 0.5V into 33 Ω: 8.2V
Cost, dual: n/a Vmin, 2.0V into 330 Ω: 12.2V


When I went into this test, I was hoping to find a chip to dethrone the OPA627 which is expensive and requires a lot of voltage. The 627 also has the characteristically mellow Burr-Brown sound, which is not always a good thing. Analog Devices chips tend to be a little snappier and more aggressive, which can help balance some systems. I wanted a chip that would fit all of these criteria while still maintaining the OPA627's incredible level of resolution and clarity. The AD843 doesn't completely fit these criteria, but it does come close.

What this chip gets right: First, the AD843 is definitely cheaper. Like the 627, the cheaper grade is fine for audio, so a pair of 843s is about half the cost of a pair of 627s. Second, this chip does have that Analog snap and verve.

The downside is that the AD843 requires more voltage than the OPA627. And like the 627, the sound gets very nasty very quickly when it starts clipping.

The AD843 seems to trade smoothness for resolution relative to the OPA627. In some cases the more detailed OPA627 might be preferrable, and in others the smoother AD843 could be helpful. I'm torn on what to make of this real difference. The OPA627 isn't hyper-revealing, and the AD843 isn't over-smooth. The OPA627's detail seems genuine; it isn't grain or overemphasized real detail. I don't mind the way the AD843 ignores these details, but at the same time I don't resent the OPA627 for presenting them. The OPA627 can be accurate to a fault, if your recording has unpleasant detail in it that another op-amp would ignore or deemphasize. If you have flawed recordings, you may prefer the pleasant lie told by the AD843.

Bottom Line: This is a serious contender with the Burr-Brown OPA627 for the title of "best op-amp I've ever heard". I view these two chips as rough equals; they're both in the same audio class, but each chip has strengths lacked by the other. Taste and system matching will be the largest factors in choosing one over the other.

Other Info:

headwize.com/ubb/showpage5.php?fnum=3&tid=1920
Analog Devices AD845 Cost, single: $6.40 (AD845JN) Vmin, 0.5V into 33 Ω: 8.7V
Cost, dual: n/a Vmin, 2.0V into 330 Ω: 9.0V


This is a very interesting chip. Sonically, you can call this a smoother, less detailed AD843. It's almost tube-like, while retaining the Analog devices snap. Compare the Burr-Brown sound which is relaxed...mellow...slower. The chip has a lot more resolution compared to lesser chips like the OPA132/134 and the AD823, but it doesn't quite match that of high-end chips like the AD843 and OPA627.

Voltage-wise, it's a somewhat hungry chip. It's only specified to run down to 9.5V, but I was able to get it to go a bit lower. In a previous listening test, I was able to take it down to about 5V. I think what is happening here is that this chip has tolerable distortion behavior when clipping, so a bit of clipping is tolerated better than with other chips.

The chip is also a bit of a pig when it comes to current draw. Each chip draws about 10 mA quiescent, which will of course go up in normal operation, and you need two chips for stereo. Heaven help you should use the chip in a battery-powered Hansen or CHA47 amp, where you need four chips!

Bottom Line: If you're building a wall-powered amp and want a snappy sound and either want to save some money or smooth over some detail relative to the AD843, this is a good chip. However, I think you should make the small step up to the 843 instead. This would be okay in a high-end battery-powered amp where sound quality is more important than battery life, yet going up to the 843 is too much.

Other Info:

headwize.com/ubb/showpage5.php?fnum=3&tid=1920
Analog Devices AD8065 Cost, single: $4.21 (AD8065) Vmin, 0.5V into 33 Ω: 4.0V
Cost, dual: $5.38 (AD8066) Vmin, 2.0V into 330 Ω: 5.7V


This chip is a good alternative to the AD823 and AD8610 in battery-powered amps. It draws more current than either of those, but it does run to lower voltages so it may last nearly as long on a set of batteries in some configurations. As you can see from the clipping numbers, the chip is running rail-to-rail in the 330 Ω test: 2Vrms is 5.656V peak-to-peak. You can't get better than that.

This chip kind of splits the difference between the AD8610 sound and the Burr-Brown sound: not aggressive, but not laid-back, either. It's a bit veiled, which is expected given the chip's price.

This chip is rare in that it is only rated for a 24V supply. (Absolute maximum is 26.4V.) Another oddity is that it is only available in SOIC versions, so you need to mount it on a Brown Dog adapter to use it in amps that use DIP chips.

Bottom line: This may be the ideal chip for you if you're running a battery-powered amp and the AD8610 is too aggressive and the OPA227 too laid-back.
Analog Devices AD8397/AD45048 Cost, single: n/a Vmin, 0.5V into 33 Ω: 4.0V
Cost, dual: $5.38 (AD45058) Vmin, 2.0V into 330 Ω: 6.4V


Full review to come later.

(According to a well-placed source, the AD8397 and the AD45048 are the same chip, characterized for different markets. This test was done with an AD45048.)
Analog Devices AD8512 Cost, single: n/a Vmin, 0.5V into 33 Ω: 4.5V
Cost, dual: $3.89 Vmin, 2.0V into 330 Ω: 7.4V


This chip is very similar to the AD823. The main differences are that it has higher output current and lower supply current. The sound quality is similar, though where I'd call the AD823 aggressive, I'd call the 8512 a bit harsh. The sound isn't nasty by any means, just not as euphonic as other chips I've reviewed here.

Bottom line: This chip is best when battery savings are the absolute most important thing and the 823's low output current is a problem. If you can tolerate higher supply current or higher voltage requirements, there are better sounding chips.
Analog Devices AD8610/AD8620 Cost, single: $8.00 (AD8610) Vmin, 0.5V into 33 Ω: 5.7V
Cost, dual: $13.33 (AD8620) Vmin, 2.0V into 330 Ω: 7.6V


This is quite possibly the best chip for battery-powered amps, period. Its voltage tolerance is among the lowest of all the chips I mention here, it has good output current abililty, it has among the lowest supply current of any chip reviewed here, and above all it sounds good.

What does it sound like? Well, take the AD823, and remove some of the aggressive harshness. Add a bit of detail and smoothness from the AD843. That's the 8610. It's not a smooth chip, just not harsh. It's not the most detailed chip, but not heavily veiled, either.

This chip is rare in that it is only rated for a 26V supply. (Absolute maximum is 27.3V.) Another oddity is that it is only available in SOIC versions, so you need to mount it on a Brown Dog adapter to use it in amps that use DIP chips.

Bottom line: This is a contender for my favorite chip of all time, especially in battery-powered amps. When paired with an aggressive or very revealing system, this chip can be unpleasant. This chip is at its best complementing a smooth, laid-back system.
Analog Devices OP275 Cost, single: $2.13 Vmin, 0.5V into 33 Ω: 17.0V
Cost, dual: n/a Vmin, 2.0V into 330 Ω: 10.0V


Full review to come later.
Burr-Brown OPA2107 Cost, single: n/a Vmin, 0.5V into 33 Ω: 10.6V
Cost, dual: $12.25 Vmin, 2.0V into 330 Ω: 10.6V


Full review to come later.
Burr-Brown OPA132 Cost, single: n/a Vmin, 0.5V into 33 Ω: 5.5V
Cost, dual: $5.40 (OPA2132PA) Vmin, 2.0V into 330 Ω: 8.3V


This is a nice family of op-amps. The sound has the typical Burr-Brown laid-back nature. It's a bit tubby on the bottom end. This is not an exciting sounding chip, but it does tend to counteract the flaws in many low-end audio systems, especially portable ones.

Digi-Key only carries the dual versions (2132) in DIP packages, and there are two grades, differentiated by whether there's an 'A' in the part name. I've been unable to find a case where the 2132PA performs worse for audio amplification than the 2132P. From a look at the datasheet, it looks like the advantages of the non-A grade are in DC specs, which of course aren't all that important to audio.

Bottom Line: A very good chip to start with. Indeed, you may be so happy with it that you stop looking at other chips!
Burr-Brown OPA134 Cost, single: n/a Vmin, 0.5V into 33 Ω: 5.7V
Cost, dual: $2.63 Vmin, 2.0V into 330 Ω: 8.4V


This is the audio grade version of the OPA132 family. (That's "audio grade" in the commercial sense, not the audiophile sense. Read: "lower quality".) Digi-Key only carries the dual version (2134) in DIP packages.

The OPA134 requires a bit more voltage than the OPA132 does. This won't matter in circuits that have plenty of voltage, but in a battery powered system a 132 can pay for itself by letting you run longer on a battery.

I found in earlier testing that the 134 was more likely than a 132 to become unstable in marginal circuits. Sometimes raising the supply voltage was all it took to make the 134 stable, and other times only swapping in a 132 would fix the problem. If you're building your own circuit from scratch and you aren't very experienced, the extra cost of the 132 can pay for itself in a better likelihood of success.

Bottom Line: If your circuit is solid and you have a fairly high supply voltage, the 134 is better than the 132 because it's cheaper and they sound identical to me. The 132 is better for more marginal setups.
Burr-Brown OPA227 Cost, single: n/a Vmin, 0.5V into 33 Ω: 5.4V
Cost, dual: $3.53 (OPA2227PA) Vmin, 2.0V into 330 Ω: 8.2V


This family of opamps sounds very similar to the OPA132 and OPA134 families. The main difference is that the 227 isn't as tubby on the bottom end as the 132. The 227 will run to slightly lower supply voltages than the 132 family.

Digi-Key only carries the dual versions in DIP packages. The 'A' versions are the right ones for audio, as the non-A version simply has better DC specs, which is not useful for audio.

Bottom Line: This is a good alternative to the OPA132. It is arguably even a significant upgrade.
Burr-Brown OPA228 Cost, single: $2.36 (OPA228PA) Vmin, 0.5V into 33 Ω: 5.1V
Cost, dual: n/a Vmin, 2.0V into 330 Ω: 8.0V


As the OPA637 is to the OPA627, so the OPA228 is to the OPA227.

Being a faster chip (33 MHz vs. 8 MHz), it wasn't stable in some of my amps, probably due to minor circuit layout problems. I got it to oscillate outright occasionally, and other times I just got a kind of "grunge" in the sound.

When I was able to avoid instability, it sounded a bit more analytical than the OPA132. By comparison, the 132 sounded more "alive". This difference is purely subjective, so some people may prefer the difference.

Bottom Line: I'm not happy with this chip for audio. If your audio tastes are like mine, you'll be happier with the OPA227. This chip will run to even lower voltages, though, so perhaps it's a good idea for battery-powered amps that need to drive headphones that need fairly high voltages.
Burr-Brown OPA602 Cost, single: $7.60 Vmin, 0.5V into 33 Ω: 10.2V
Cost, dual: n/a Vmin, 2.0V into 330 Ω: 9.6V


Full review to come later.
Burr-Brown OPA604 Cost, single: $2.36 Vmin, 0.5V into 33 Ω: 8.6V
Cost, dual: $4.28 Vmin, 2.0V into 330 Ω: 11.4V


The specs on this chip are very similar to that of the OPA132/134 family: some specs are a bit better, and some a bit worse. Like the OPA134, this one is specifically sold with audio in mind. It's been used in several popular bits of audio gear, especially near the low end of the audiophile range.

For a headphone amp, the most significant spec difference is that the 604s require more voltage than the OPA134/132s to sound good. If you're going to use a battery power supply, you should use two 9V batteries or at least 8 cells for AAs or similar.

This chip has a problem with oscillation, no doubt because it's a "fast" op-amp: 20 MHz, vs. the OPA134/132 family's 8 MHz. In one of my Hansen-type amps configured with OPA2604APs, I was able to make it oscillate by giving it a supply voltage anywhere over 18V. In other amps, I was able to give it as much as 34VDC without causing oscillation. In my main test amp, I didn't have any oscillation problems. It's hard to pin down a source of blame for this problem. The only solid lesson I have been able to draw from this so far is that this chip is simply harder to use than the OPA134/132 family.

Sonically, the OPA604 family is almost identical to the OPA134/132. I did hear slight differences, but I was at a complete loss when trying to put these differences into words. Because of the advantages of lower supply voltage and oscillation-free operation, the OPA134/132s are still more desirable chips for headphone amps.

Bottom Line: Use this only if you can't find an OPA134/132.
Burr-Brown OPA627 Cost, single: $18.38 (OPA627AP) Vmin, 0.5V into 33 Ω: 6.8V
Cost, dual: n/a Vmin, 2.0V into 330 Ω: 9.8V


The first thing I noticed is the cleanliness of the sound. With this chip in the test amplifier, I heard known problems in a low-end portable source more clearly than with my reference for this test, the OPA134PA. The 627 also seems to do better on recordings with room ambience: it reveals details about the acoustic space that the OPA132/134 chips will hide, making them sound "flat" in comparison. But these two chips are more alike than different. Both have the characteristic laid-back and dark Burr-Brown sound, and both are very tolerant, stable chips.

The only remaining differences are that the OPA132/134 family will work well below 9V, whereas the 627's performance falls off a cliff below the clipping points I give above. There does seem to be a bit of extra low bass impactfulness with the 627. This seems less to be "extra power" than a removal of some heavier thumpiness in the 132/134 — the 627 seems to have a truer, more refined kind of bass.

In all my testing, I've been unable to hear a difference between the OPA627AP and the OPA627BP. The datasheet says that the differences between the grades are in the DC specs, so this is not surprising.

Bottom Line: The sonic differences between the OPA627/637 and the OPA132/134 are of the "last 5%" variety, rather than providing a dramatically different sound. If you like the Burr-Brown sound and can stand to pay 14× as much as for an OPA2134PA, a pair of OPA627APs is a reasonable investment. I see no reason to pay extra for the B grade in an audio application.

Other Info:

headwize.com/ubb/showpage5.php?fnum=3&tid=774

headwize.com/ubb/showpage5.php?fnum=3&tid=1865
Burr-Brown OPA637

The OPA637 is simply the "uncompensated" version of the OPA627. This means it has a higher bandwidth, but that it won't be stable at low gain levels. The datasheet says that it is minimally stable at a gain of 5, but as with all chips, the higher the gain, the more stable it becomes. The cost and voltage performance are the same as for the 627.

The higher bandwidth of the 637 results in a somewhat more lively sound than the 627. It still has the overall laid-back Burr-Brown characteristic, though. Given the choice between these two chips, I use the 637 when I can live within its gain requirements, but I happily fall back to the 627 otherwise.

Other Info:

headwize.com/ubb/showpage5.php?fnum=3&tid=1197
National Semiconductor LF355 Cost, single: $0.94 Vmin, 0.5V into 33 Ω: 14.9V
Cost, dual: n/a Vmin, 2.0V into 330 Ω: 10.3V


Yet another jellybean chip. The full family is LF355-LF357. Specwise, these are very similar to the TL071. A related chip is the LF351, discontinued by National but picked up by makers of generic chips like ST and Fairchild.

Notice that this chip doesn't like to drive low impedances.
National Semiconductor LM6171 Cost, single: $2.83 Vmin, 0.5V into 33 Ω: 6.1V
Cost, dual: $3.80 Vmin, 2.0V into 330 Ω: 9.5V


Digi-Key carries the LM6171BIN single-channel version, and the LM6172IN dual version in the DIP package.

This is a very high-speed op-amp with bipolar input transistors. Translated, that means this op-amp is hard to use. However, it has exemplary audio performance for such a low price, so experienced builders should at least consider using it. If you decide to give it a shot, you must design the amp around the chip: you cannot just pop the chip into an existing circuit and expect it work. (For info on what's necessary to make this chip work, see the companion article, "Working with Cranky Op-Amps".)

I made another test amplifier according to that article's principles in order to test this chip. To assure myself that the necessary design changes didn't impact the sound, I tried some of the other chips in it. This brings up an important point: the changes necessary to make chips like the LM6171 work in a CMoy amp do not prevent less picky chips from working. If you think you might want to try a chip like this someday, you might make the design changes from the start so you're free to use most any chip in the amp.

Sonically, this chip is significantly more revealing than the OPA132/134 series, and the bass is a touch more impactful as well.

With a high supply voltage (15V), the difference between the LM6172 and the OPA134PA is subtle, but real. At lower supply voltages, the LM6172 can greatly outshine the OPA132/134 series. The clipping numbers above don't tell the full story; when this chip clips, it does so in a very soft, rounded way, instead of the harsh clipping you get with other chips. This means you can often run the chip to lower voltages than my tests indicate by accepting a mild form of distortion.

Bottom Line: This chip is not for tyros, but it's cheap, it performs very well at low voltages, and at higher voltages it still outshines many other chips in its price class. It requires more external components to achieve that performance, however.

Other Info:

headwize.com/ubb/showpage5.php?fnum=3&tid=2222
Signetics NE5532 (various vendors) Cost, single: n/a Vmin, 0.5V into 33 Ω: 5.6V
Cost, dual: $0.80 Vmin, 2.0V into 330 Ω: 8.9V


Another jellybean chip, but bipolar-input so it requires more care in application. Probably better than the TL072 for audio.

Full review to come later.
Texas Instruments TL07x (various vendors) Cost, single: $0.48 (TL071CP) Vmin, 0.5V into 33 Ω: 17.3V
Cost, dual: $0.64 (TL072CP) Vmin, 2.0V into 330 Ω: 12.3V


This is a jellybean chip that was popular for audio back in the 80's. Open up an old CD player or preamp, and there's a pretty good chance you'll find a TL072.

The 071 is the single version, and the 072 is the dual. There is also a letter or three in there, which indicates the part's tolerance and sometimes a variation code. In increasing levels of quality, they are: C, AC, BC. (I'm ignoring the special-purpose industrial and mil-spec grades.) I can't hear the difference between the grades, so get the C grade. The price is for TI's version, since they invented the chip.

This family of chips is not as good as the OPA132/4 family. The clipping numbers above are informative here: this is one of the few chips I've tested that required more supply voltage on the 33 Ω test than on the 330 Ω test. Bottom line, this chip does not like to drive low impedances. I've heard members of this op-amp family distort even at the chip's full operating voltage of 30V. I'm not talking about minor problems here — I'm talking about crunchy, ugly, obvious distortion. Therefore, I recommend using this chip only under duress, and then only if you're willing to give it a fairly high supply voltage.

Bottom Line: This chip is very common and cheap, but also sonically inferior to all other chips tested so far. Use it only if you can't find anything better.
Texas Instruments TL08x (various vendors)

This is a lower-spec version of the TL07x. I can't hear a difference between the two, but since the TL07x is the same price you might as well get that one. As I said above, these chips are classic audio jellybeans, mainly useful when the chip doesn't have to drive a low-impedance load.

The only reason I've bothered to review the 082 here is that you can get them at Radio Shack. If you need an op-amp in an emergency, it's good to know that you can pay the moderately obscene sum of $1.99 each to get usable chip without having to wait for mail order.
"29 poslednjih dana u mesecu je najteže"

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Stolle
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Postovi: 24768
Pridružen: 12 Avg 2006, 23:35
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Re: CD player upgrade

Post napisao Stolle » 22 svi 2010, 22:43

Još neke ocene:
The Op amp supplied with the Chiarra kit is the LF 353 which is a design that stems back to the early 1970's. I wanted to experiment with some of the more modern Op Amps to see if they could improve on the sound of the LF353. All opamps are direct drop in replacements and there is no need for any soldering as the Chiarra comes with a high quality gold turned pin DIP8 socket so rolling op amps couldn't be easier!

The Grand line up

LF 353 (Dual)
Burr Brown OPA 2604 (Dual)
Burr Brown OPA 2132 P (Dual)
Burr Brown OPA 2227 P (Dual)
Burr Brown OPA 2228 P (Dual)
AD823 AN (Dual)
AD712 JN (Dual)
OPA 627 BP (Single)




Test one: LF 353 Price: £0.40p

This is the op amp that comes supplied with the kit and it really doesn't do the amp much justice sounding shrill, grainy and very "in your face". It is actually very similar sounding to the valves that come supplied with the musical fidelity X-Can V2... on some high notes the LF 353 can produce ear bleeding harshness. Remove this (don't fit it in the first place) and go for something better if you want to hear the amp at its best. 4.5 / 10

Test two: Burr Brown OPA 2604 Price: £2.50

OPA2604 sounded very warm, very laid back and very easy to listen to but slightly veiled in the detail department. "Chocolaty" and "syrupy" though a good easy to listen to Op amp but not my cup of tea as I prefer a greater insight into the mix. Having said that, however, this may just be what the doctor ordered for those who like a laid back, thick, chocolaty, easy going and easy to listen to sound. 6.5 / 10
Test three: Burr Brown OPA 2228 / 2227 Price: £3.00

These chips makes the sound more valve like than the X-Cans ever did if that can possibly make any sense! (I couldn't detect any sonic differences between the 2227 & 2228) Melodious, slightly laid back and warm yet it brings out every last bit of detail from a recording. Overall a very nice sound. A kind of hybrid valve and solid state mix which gives the best of both worlds. Nice smooth valve like mids and highs with lovely solid state bass oomph . This is the Op amp for those who prefer a valve like sound but would also like a solid state bottom end delivery. With this Op amp you can have your cake and eat it. 7.5 / 10

Test four: Burr Brown OPA 2132 Price: £4.00

Smooth, highly analytical, warm, uncoloured, laid back yet all detail is present (and then some) Very electrostatic quality to the sound with that super solid state bass underpinning the proceedings without overwhelming them. Start and stops are followed by an inky black silence and the timbre of the drums is very realistic indeed. Something that is very evident with this op amp is it's inherent ability to provide accurate timing which I really do like! There is no bass overhang, the drums start and stop as they should and, as a result, the timing is pretty much spot on. This is like listening to music with a stethoscope with the metronome ticking away in the background but it also adds a touch of valium to make the experience very bearable and extremely enjoyable. 7.5 / 10

Test Five: AD 823 AN (Analogue Devices) Price: £3.00

Without a shadow of a doubt this op amp is the star of the show so far. From the moment I rolled this into the amp I knew it was a winner. It provided very similar results to the OPA 2132 but each component of the sound was treated to an additional air of realism and effortless delivery that was immediately evident. Easy to listen to, easy to pick out every last detail and ever so natural. There was an ethereal quality to the sound that I have only ever heard on high quality loudspeaker based systems. It's hard to put what this op amp does into words but listening to the sound with it on board is as close to headphone heaven I have yet been. 9 / 10

Test Six: AD 712 JN (Analogue Devices) Price: £4.50

A "Very" revealing chip, similar to the AD823 but rougher around the edges. I don't know if the roughness was on the actual recording or if it was attributable to the AD712 but I found this chip gave out "way" too much information for my liking. It is analytical to the point that certain pieces of music can become impossible to listen to, especially bad recordings, it reproduces every last detail / imperfection with microscopic accuracy which, at times, can be detrimental to the overall enjoyment of the music. For those that love a warts and all insight into the music then this is the star of the show but it may not be to everyones liking. 8.5 / 10

Test Seven: Burr Brown OPA 627 BP on Browndog adaptor Price: £28 each (Total £56 for 2 singles) Browndog adaptor £5 Total: £61

Two words sum this chip up........ "absolute class" This is the only single chip in the test (the rest all being duals) and it was necessary to fit two single channel 627's onto a single to dual Browndog adaptor which Adapts two single-channel DIP-8 op-amps to a dual DIP-8 pinout. These 2 single channel op amps absolutely trounced anything that had gone before them in this test..... the width of the soundstage, the clarity and the sheer presence make this my choice of op amp for use in the Chiarra without a shadow of a doubt. The sound is just so "clean", so "natural", so "musical" and so "detailed" with the 627's on board. I said the AD 823 was "as close to headphone heaven I have yet been" The Burr Brown 627 "is" headphone heaven....... absolute class act. 10 / 10
"29 poslednjih dana u mesecu je najteže"

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Stolle
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Pridružen: 12 Avg 2006, 23:35
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Re: CD player upgrade

Post napisao Stolle » 22 svi 2010, 23:03

I ako ništa drugo ne menjate, samo zamenom operacionih pojačivača u izlazu rezultat će vas iznenaditi. Naravno da je to samo prvi korak kod upgrade-ovanja, ali mnogima je i sasvim dovoljan.
U obzir treba uzeti:
Analog Devices: AD712, AD825 (single), AD8065 (single), AD8066
Burr-Brown: OP2604, OP2134, OP2132, OP627 (single)
Treba paziti koji su single i dual. Kod smd treba pločica adapter, ako su pojedinačni onda pločica za dva.
Evo i par primera.
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