Hello , A year ago I got this system as a gift for my birthday .
The " towers " speakers I use on my Pionner amp ( a702r ) and the rear speakers I use for PC with the Akai amp ( on the front , in stereo mode . it has two tda2030's bridged per channel Left front , Right front and Center. and the rear has only one tda2030 per channel )
The amp has 8 TDA2030 ( it sounds better than other amps with tda2030 i have heard ) I just opened it and started to laugh , it has a few op-amps LF356 for microphone inputs and 4558 ( LOL ) even with these it sounds surprisingly good. What about if I change the TDA2030's with LM1875 and the op amps with something " better " even NE5532 are better than 4558 from what I've read about 4558 , maybe some OPA2134 . What you think ? would it be worth ? .
Also I have tested the 4558 on rod elliot's op amp preampifier schematic with other op amps and the 4558 didnt sounded bad to me. I liked it over TL072 ( maybe the TL072 wasnt working well on that schematic ) Schematic is High Quality Audio Preamp (Mk II) Project 88
The " towers " speakers I use on my Pionner amp ( a702r ) and the rear speakers I use for PC with the Akai amp ( on the front , in stereo mode . it has two tda2030's bridged per channel Left front , Right front and Center. and the rear has only one tda2030 per channel )
The amp has 8 TDA2030 ( it sounds better than other amps with tda2030 i have heard ) I just opened it and started to laugh , it has a few op-amps LF356 for microphone inputs and 4558 ( LOL ) even with these it sounds surprisingly good. What about if I change the TDA2030's with LM1875 and the op amps with something " better " even NE5532 are better than 4558 from what I've read about 4558 , maybe some OPA2134 . What you think ? would it be worth ? .
Also I have tested the 4558 on rod elliot's op amp preampifier schematic with other op amps and the 4558 didnt sounded bad to me. I liked it over TL072 ( maybe the TL072 wasnt working well on that schematic ) Schematic is High Quality Audio Preamp (Mk II) Project 88
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Hi Bruno,
Don't use sockets. You would have a huge problem trying to use better than the 5532's. They are better than the output chips in there. Sockets increase capacitance between pins (not good) and may have poor contact. Soldering them in is cheaper and better for contact. 18 volt supplies are fine. These may draw a little more than the 4558 chips.
-Chris
Don't use sockets. You would have a huge problem trying to use better than the 5532's. They are better than the output chips in there. Sockets increase capacitance between pins (not good) and may have poor contact. Soldering them in is cheaper and better for contact. 18 volt supplies are fine. These may draw a little more than the 4558 chips.
-Chris
They not only "may", they most definitely will (8-9 mA a pop vs. 3.5 mA or so?). Whether that is any kind of problem will depend upon the power supply - a simple zener job may not tolerate too much more.
I tend to refrain from giving opamp swapping advice until I've seen the schematic. If you have a unity-gain buffer that has to drive 10 kOhms up, for example, even a humble 4558 will do a perfectly fine job. In P88 we're looking at relatively light loading and nonideal impedance balance in a noninverting circuit - the latter would in fact give a 4558 (and other bipolars) an advantage over a TL07x, which really is better-suited to inverting operation.
LF356 is a bit of an odd choice for a mic preamp, it's pretty good at output driving for its age but doesn't have particularly low voltage noise. Then again, this would mean decent distortion even at high gain with limited GBW, so it makes sense from that POV. I'd rather be using an NE5534(A) though.
BTW, did this Akai unit drop out of the late '90s or something? It sure looks the part. That would explain parts choices, too.
I tend to refrain from giving opamp swapping advice until I've seen the schematic. If you have a unity-gain buffer that has to drive 10 kOhms up, for example, even a humble 4558 will do a perfectly fine job. In P88 we're looking at relatively light loading and nonideal impedance balance in a noninverting circuit - the latter would in fact give a 4558 (and other bipolars) an advantage over a TL07x, which really is better-suited to inverting operation.
LF356 is a bit of an odd choice for a mic preamp, it's pretty good at output driving for its age but doesn't have particularly low voltage noise. Then again, this would mean decent distortion even at high gain with limited GBW, so it makes sense from that POV. I'd rather be using an NE5534(A) though.
BTW, did this Akai unit drop out of the late '90s or something? It sure looks the part. That would explain parts choices, too.
The TL072 and family isn't a good choice for many things with its very limited current output. Depending on how many op amps are involved, the power supply might be an issue, that's true. I don't recommend using premium grade op amps in this amp. They perform at a level much higher than the output stage.
The 5532 is still considered an extremely good part, and with the prices being so low these days .. they represent great value. The 5534 is still considered to be among the better op amps even today.
-Chris
The 5532 is still considered an extremely good part, and with the prices being so low these days .. they represent great value. The 5534 is still considered to be among the better op amps even today.
-Chris
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