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NE5534 circuit. I need more bass. Help!!
NE5534 circuit. I need more bass. Help!!
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Old 12th February 2018, 04:51 PM   #81
cliffforrest is offline cliffforrest  United Kingdom
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NE5534 circuit. I need more bass. Help!!
Quote:
Originally Posted by ammel68 View Post
What do you REALLY expect here?
Do you, for some bizarre reason, think the the NE5532 and 5534 are the "Holy Grail" of op-amps when it comes to sound quality?
If so, I can tell you without a shadow of doubt that they are NOT having trying many op-amps in many different applications over the years.

Why don't you throw the '5534 and its dual counterpart '5532 in the trash where they belong and move on to other more modern and better sounding op-amps?

You have a LOT to learn about audio op-amp circuits, so I wish you nothing but the best of luck with your venture!
And that is about the most unhelpful and arrogant reply to someone who struggling to get a basic circuit to work at all. Op-amp rolling! Give me a break!

The most likely problem here is something very miswired, wrong value component and / or oscillations.
How have you built this circuit? Can you show a clear photo of the components?

Unless something is really askew, an opamp circuit with fixed gain (set by resistor values) will be flat across the audio band. So something is DRASTICALLY wrong. This is difficult for a beginner with no test equipment and limited knowledge.

The 1pF cap bothers me! That is the capcitance of two wires close to each other!

Check all your components and values, post the clearest possible photos.
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Old 12th February 2018, 05:02 PM   #82
rmaudio is online now rmaudio  United Kingdom
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+1
I suggest to the OP that starting point to sort this would be to redraw the schematic clearly with a 'proper' op amp symbol
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Old 12th February 2018, 06:45 PM   #83
dj_holmes is offline dj_holmes  United Kingdom
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there is nothing wrong with the ne5534/32. They can have good bass its just logical the culprit is the circuit design.

I don't have my camera now and the amp is packed away again! But then what will you see as the circuit diagram is very accurate!

With the exception of another resistor at input the circuit for ne5534 is highly accurate.

Rayma kindly suggested changing the 30k to 100k and it worked except for the massive DC offset. Even I know 200mv is very bad!

And that the only real progress!! Ne5534 is fine, the is no distortion etc. The sound is excellent just needs more bass!!!!! Bit flat and bright thats all.

I'm willing to bet money its one or two resistors but only an expert can say which ones! Help!! Please!
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Old 13th February 2018, 12:30 PM   #84
rmaudio is online now rmaudio  United Kingdom
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Quote:
Originally Posted by dj_holmes View Post
there is nothing wrong with the ne5534/32. They can have good bass its just logical the culprit is the circuit design.

I don't have my camera now and the amp is packed away again! But then what will you see as the circuit diagram is very accurate!

With the exception of another resistor at input the circuit for ne5534 is highly accurate.

Rayma kindly suggested changing the 30k to 100k and it worked except for the massive DC offset. Even I know 200mv is very bad!

And that the only real progress!! Ne5534 is fine, the is no distortion etc. The sound is excellent just needs more bass!!!!! Bit flat and bright thats all.

I'm willing to bet money its one or two resistors but only an expert can say which ones! Help!! Please!
It sounds like there is something wrong with the circuit you have put together.
But on the offset - first I'd say that 200mV isn't that big a deal wrt +15V supplies (max output, say circa 13V depending on load ) so just losing a bit of headroom. With a 5534 you'll need to ac couple the output in any case and the amp you're feeding almost certainly has ac coupled input in any case.

But to get reduce it to by getting rid of the gain at DC then you put a big ol' cap between the resistor from the -ve input that currently goes to 0V and 0V.
ie detatch it from ground and put a cap in the gap. If using polarised electrolytic with 5534 then put -ve cap pin to 0V.
Gain at DC is then unity.
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Old 13th February 2018, 01:08 PM   #85
Ola is offline Ola  Estonia
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Put at least 2 200, better 4 700 uF caps to power rails
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Old 13th February 2018, 01:09 PM   #86
Ola is offline Ola  Estonia
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Bass in subjective lend depends firsthand on power rails capacitance. 10 000 uF each rail .... try, You will lovw it
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Old 13th February 2018, 01:49 PM   #87
rmaudio is online now rmaudio  United Kingdom
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Quote:
Originally Posted by Ola View Post
Bass in subjective lend depends firsthand on power rails capacitance. 10 000 uF each rail .... try, You will lovw it
You don't need anything like that capacitance.
It's not a power amp !
What you need depends on the power supply and physical arrangement / cable lengths etc.
In general any reasonable value of bulk decoupling where the power comes onto the board - 100uF is fine. One per rail to 0V.
Then say 100nF Ceramic or Polyester between +15V and -15V near the 5534.
You may want to put small, say 10R, resistors or ferrite beads in series with the +/-15V rails to the 100nF cap.
However I do see from the sketch that only one 22uF cap is shown between +15V and -15V and the +15V isn't shown as connected to anything else - I assume it is actually connected on the hardware.

Please don't tell me this isn't enough - I have a bunch of circuits about 10m away from where I am sitting that shows it does - apart from thousands of audio circuits and channels in operation.

Anyway, unless the OP has stability / oscillation problems this isn't the issue.

Last edited by rmaudio; 13th February 2018 at 01:52 PM.
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Old 13th February 2018, 01:54 PM   #88
anti is offline anti  Slovakia
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To keep the DC offset low, you need to keep the resistances the the inputs see balanced like you have now (36k + 4k7 positive in) and (43k || 220k negative in).

Another wiggle you could try is to up the 36k to 39k, reduce the 4k7 to 1k8 or 1k5; and up the 220pF cap some - I'd try 470pF and go up to 1nF...

Of course, upping the 2u2 input cap would add more bass impact than any of above.
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Old 13th February 2018, 02:21 PM   #89
anatech is offline anatech  Canada
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NE5534 circuit. I need more bass. Help!!
Hi dj_holmes,
I wonder if that op amp isn't oscillating. The 1 pF capacitor across the 220K in the feedback network isn't enough. Your gain is also really high. If anything, you should be hearing bass without much in the way of highs.

Try increasing the 1 pF capacitor to 22pF and go higher. If you have an oscilloscope, you could easily see what the circuit was doing. The NE5534 is an excellent op amp for audio.

Your DC offset isn't surprising since your gain is so high. You might want to break down the stage into two op amps with each at a reasonable level of gain. You can control things much better and your DC offset should really drop to the < 10 mV level

-Chris
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Old 13th February 2018, 04:04 PM   #90
rmaudio is online now rmaudio  United Kingdom
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Offset is irrelevant to the OP's issue unless the signal is crashing into the rails then it would give severe distortion.
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