So I needed a circuit to act as a bass boost. I ended up adapting this circuit (by ESP Sound) by excluding everything but the 35-150hz part.
This simulates perfectly in LTspice.
However, when I try and convert it so that the op amps use a single supply - GND to 12.6V - something goes wrong, and I don't know what.
I added R1 to bias the input. R4/R5 and R7/R8, as well as R10, represent pots. They adjust the volume, amount of bass boost, and the frequency of the boost, resp. The output is 0V - no signal. The transient analysis shows the output is attenuated by about 100dB.
Can anyone help me fix the circuit? Using a dual PS is not an option.
Thanks,
Hengy
An externally hosted image should be here but it was not working when we last tested it.
This simulates perfectly in LTspice.
An externally hosted image should be here but it was not working when we last tested it.
However, when I try and convert it so that the op amps use a single supply - GND to 12.6V - something goes wrong, and I don't know what.
An externally hosted image should be here but it was not working when we last tested it.
I added R1 to bias the input. R4/R5 and R7/R8, as well as R10, represent pots. They adjust the volume, amount of bass boost, and the frequency of the boost, resp. The output is 0V - no signal. The transient analysis shows the output is attenuated by about 100dB.
An externally hosted image should be here but it was not working when we last tested it.
Can anyone help me fix the circuit? Using a dual PS is not an option.
Thanks,
Hengy
So I fixed what you suggested, but it didn't fix it.
Hengy
An externally hosted image should be here but it was not working when we last tested it.
Hengy
What others told you about a shorted capacitor and missing bias is true. What isn't true is that being a parametric equalizer. Those are tunable gyrators but you can't easily alter the 'Q' in this scheme and have a narrow tuning range. Look up 'state variable' filters.
The Technics SH-9010 form the late '70s used state variable filters and allowed 9:1 tuning range and 10:1 'Q' (7 to 0.7) on each of 5 bands. They called it a 'universal frequency equalizer'.
G²
The Technics SH-9010 form the late '70s used state variable filters and allowed 9:1 tuning range and 10:1 'Q' (7 to 0.7) on each of 5 bands. They called it a 'universal frequency equalizer'.
G²
Years ago I made 2-channel/2-band parametric eq's using a ckt that was published in Popular electronics mag, sept 1979, still have a few spare parts and a working unit. I can sell you some of these parts, Alps pots, switches. I guess posting the article, would be okay, if I am not in violation of a copyright?
Hello copyright police, is this okay?
It used TL074CN, as they were new at that time. Let me know if I can help.
Low ban was set at 40-960Hz,+/-20dB@Q=0.16 octaves, +/-12dB@Q=2 octaves
It worked really nice!! I sold a few of them.
There is also Walt Jung's SV EQ ckt's as he published in "Audio IC OPA App's" handbook, p161,fig5-25, it was a 3-band design and had a larger Q range,0.74-4. Maybe Walts' web site has this information, so I do not have to provide it, or violate a copyright.
This stuff brings back memories. I do not use tone control much anymore, as I have very good speakers that do not need tone control, but there are times they can be used, as I guess that you have a reason for needing them.
Rick
Hello copyright police, is this okay?
It used TL074CN, as they were new at that time. Let me know if I can help.
Low ban was set at 40-960Hz,+/-20dB@Q=0.16 octaves, +/-12dB@Q=2 octaves
It worked really nice!! I sold a few of them.
There is also Walt Jung's SV EQ ckt's as he published in "Audio IC OPA App's" handbook, p161,fig5-25, it was a 3-band design and had a larger Q range,0.74-4. Maybe Walts' web site has this information, so I do not have to provide it, or violate a copyright.
This stuff brings back memories. I do not use tone control much anymore, as I have very good speakers that do not need tone control, but there are times they can be used, as I guess that you have a reason for needing them.
Rick
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Jay,
I did find that mistake, and all my simulations are with it correctly oriented. It is also correct in my third post. Thanks
stratus46,
The project I referenced, by ESP Sound, called it a parametric EQ!
Are you saying that this won't work? That I should try a design based on a state variable filter?
The goal of this circuit is to provide both a volume control and bass gain stage before a headphone amplifier.
rsavas,
Thanks for the offer, but I am a student in a CS/Physics program, and would very much rather try building one myself (and learn from my mistakes!).
I will look into those articles you mentioned.
And thank you for understanding. I do not consider myself an audiophile, but I can recognize, and do appreciate, good sound quality and systems. I tend to turn up the bass in almost all of my music, as a personal preference.
Thanks, Hengy
I did find that mistake, and all my simulations are with it correctly oriented. It is also correct in my third post. Thanks
stratus46,
The project I referenced, by ESP Sound, called it a parametric EQ!
Are you saying that this won't work? That I should try a design based on a state variable filter?
The goal of this circuit is to provide both a volume control and bass gain stage before a headphone amplifier.
rsavas,
Thanks for the offer, but I am a student in a CS/Physics program, and would very much rather try building one myself (and learn from my mistakes!).
I will look into those articles you mentioned.
And thank you for understanding. I do not consider myself an audiophile, but I can recognize, and do appreciate, good sound quality and systems. I tend to turn up the bass in almost all of my music, as a personal preference.
Thanks, Hengy
SVF, parametric eq = the same thing
Suggest +/- v rails = more dynamic range
rather than a single supply, not having to bias OPA's at 1/2 Vcc = more components.
SVF, Sure an excellent bass control ckt, to tune a speakers low end to compensate for response roll off.
As an effect, can sweep the freq, with low Q setting, to get the ole flanger effect. Need a sweeper (triangle osc) & a var res for Freq control, say a LDR/LED combo ckt, lots to play with.
Built my SVF (ParaEq) as a college project (tone control section) , part of a pre-amp design, was impresses with the sound, used NE5533 (obsolete = 2x5534=16pin dip ) as gain cell set at a gain of ~6 (1V/150mV), plus a MM phono pre-amp, old LM381. I am amazed that this design would still be valid today as a low cost pre-amp. Of course could use newer OPA's for increased performance and change the MM phono of course.
Like to know if a young lad, would be able to hear the difference between a 5534 and a newer LME49xxx part. Let me know how it goes.
Good Luck
Rick
Suggest +/- v rails = more dynamic range
rather than a single supply, not having to bias OPA's at 1/2 Vcc = more components.
SVF, Sure an excellent bass control ckt, to tune a speakers low end to compensate for response roll off.
As an effect, can sweep the freq, with low Q setting, to get the ole flanger effect. Need a sweeper (triangle osc) & a var res for Freq control, say a LDR/LED combo ckt, lots to play with.
Built my SVF (ParaEq) as a college project (tone control section) , part of a pre-amp design, was impresses with the sound, used NE5533 (obsolete = 2x5534=16pin dip ) as gain cell set at a gain of ~6 (1V/150mV), plus a MM phono pre-amp, old LM381. I am amazed that this design would still be valid today as a low cost pre-amp. Of course could use newer OPA's for increased performance and change the MM phono of course.
Like to know if a young lad, would be able to hear the difference between a 5534 and a newer LME49xxx part. Let me know how it goes.
Good Luck
Rick
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Ok, So I was looking around the ESP site, and I came across the Baxandall tone control circuit. A few adjustments later, I came up with this. Simulates exactly what I want!
Next step is to build it.
rsavas,
I'll need to place an order from Digikey. They have the NE5534P. I'll get two, and compare them to my LME49740s I have. I like to think my ears are pretty good! (and my Audio Technica M50s, too!)
Hengy
An externally hosted image should be here but it was not working when we last tested it.
Next step is to build it.
rsavas,
I'll need to place an order from Digikey. They have the NE5534P. I'll get two, and compare them to my LME49740s I have. I like to think my ears are pretty good! (and my Audio Technica M50s, too!)
Hengy
I'm not saying it won't work, just that it's not a true parametric equalizer. I get the impression you think I'm claiming Rod is 'lying'. People say all sorts of things that aren't true by misunderstanding. I use 'lying' when someone attempts to deceive but I don't think that of Rod at all. I use him a a reference on occasion. Or maybe I'm just too picky.
This may very well be all you need. You have reduced tuning range and no control of 'Q' - while it's operating. You CAN change the 'Q' with component changes but it's not easy to do it with a pot in this configuration. Again, this may be totally satisfactory as it is. Try it and if you need more control it's possible.
G²
This may very well be all you need. You have reduced tuning range and no control of 'Q' - while it's operating. You CAN change the 'Q' with component changes but it's not easy to do it with a pot in this configuration. Again, this may be totally satisfactory as it is. Try it and if you need more control it's possible.
G²
Stratus46,
You misunderstood me! I in no way think Rod is lying. I thought that it would not work because of what I was trying to turn it into - something that I didn't fully understand. That's all. I have reward the ESP site from top to bottom many times, and consider Rod to pretty much be the authority!
I googled for a "bass boost" circuit before trying to adapt my own, but didn't find much.
The last circuit I posted does everything that I want. I think I started with something too complex with the parametric EQ.
Thanks for the help everyone.
Hengy
You misunderstood me! I in no way think Rod is lying. I thought that it would not work because of what I was trying to turn it into - something that I didn't fully understand. That's all. I have reward the ESP site from top to bottom many times, and consider Rod to pretty much be the authority!
I googled for a "bass boost" circuit before trying to adapt my own, but didn't find much.
The last circuit I posted does everything that I want. I think I started with something too complex with the parametric EQ.
Thanks for the help everyone.
Hengy
Bass boost ckts, take a look at Linkwitz Lab - Loudspeaker Design
In particular, Active Filters, shelving low pass, if all you want is extended bass boost.
In particular, Active Filters, shelving low pass, if all you want is extended bass boost.
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