I'm looking to build an EQ for a TC9 array and was hoping a PCB or kit was available to make this a bit easier. I vaguely remember it was an op amp based circuit originally used with the IDS25.
Anyone know of a source for something like this?
Anyone know of a source for something like this?
You can try this post: https://www.diyaudio.com/community/...ssion-lines-and-the-like.310150/#post-5135367
No PCB though, jus a schematic based on Roger Russell's IDS.
That took me a while on my mobile 😀
No PCB though, jus a schematic based on Roger Russell's IDS.
That took me a while on my mobile 😀
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Hope I didn't give the wrong impression, this schematic was created by @Bob Richards and checked by @xrk971 based on published graphs by Roger Russell.
Do you have the article Roger published in AudioXpress many many moons ago? I'll DM you to be sure.
I'd say what Bob and XRK did may be a good starting point but also may need some revisions based on placement of speakers in the room etc. Their journey started here: https://www.diyaudio.com/community/threads/cloning-ids-25s.203356/page-6#post-3612871
Most of us use either a PC with FIR correction capabilities or a stand alone DSP (with or without FIR) for the EQ correction. I do not recall someone trying the above schematic nor do I know someone on here that had acces to a true IDS24. When I build my speakers I've been in contact with Mr. Russell (RIP) but after some talks I could not use him or his IDS24 in my own thread, as I played with the idea to build a few commercially. I had his blessing but it did mean I had to to leave all links to his work out of my story. I never pursued this further though. But his prototypes were my big inspiration, no doubt. You could say I tried to evolve from where he started.
Do you have the article Roger published in AudioXpress many many moons ago? I'll DM you to be sure.
I'd say what Bob and XRK did may be a good starting point but also may need some revisions based on placement of speakers in the room etc. Their journey started here: https://www.diyaudio.com/community/threads/cloning-ids-25s.203356/page-6#post-3612871
Most of us use either a PC with FIR correction capabilities or a stand alone DSP (with or without FIR) for the EQ correction. I do not recall someone trying the above schematic nor do I know someone on here that had acces to a true IDS24. When I build my speakers I've been in contact with Mr. Russell (RIP) but after some talks I could not use him or his IDS24 in my own thread, as I played with the idea to build a few commercially. I had his blessing but it did mean I had to to leave all links to his work out of my story. I never pursued this further though. But his prototypes were my big inspiration, no doubt. You could say I tried to evolve from where he started.
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Wow that is some way back stuff Wesayso! I forgot all about that but now that you show it - seems like a nice a EQ circuit for a line array to get a neutral response with good bass.
Yea, that looks like a simple elegant circuit for the job. I'd definitely add a balanced transformer output to that. I have a DC coupled, balanced input amp which responds well to transformer coupling.
https://reverb.com/item/86219676-klark-teknik-dn360-2-channel-30-band-graphic-eq-2010s-silver
These analog units are easily available pre owned for Pennies on the dollar value……and they sound amazing
These analog units are easily available pre owned for Pennies on the dollar value……and they sound amazing
That op amp circuit brings back memories of my own first projects as a newly minted engineer in the 70's. Today though I can't imagine anything easier than a miniDsp. Nothing simpler than the analog circuit, IF you can stand to keep your hand off it instead of endlessly changing resistor values to tune the response.
It looks like the original IDS25 EQ circuit is designed for fet input op amps ie. TL072. I was going to build a bipolar version with NE5532s but that changes the resistor values around the feedback and input legs due to different input biasing. The LF and buffer section are easy to adapt for bipolar op amps, but the HF section requires more complex changes to keep a bipolar op amp bias balanced.
@mayhem13 I have a couple of DN410 parametric EQs, but I wouldn't consider them low noise compared to a well designed op amp EQ circuit with only a few op amps in the signal path.
@mayhem13 I have a couple of DN410 parametric EQs, but I wouldn't consider them low noise compared to a well designed op amp EQ circuit with only a few op amps in the signal path.
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@nc535 yes, the DSP route would be simpler and more refineable but I don't want a AD/DA step in my main signal path for several reasons. For sake of initial tuning and deriving a final EQ curve I have the versatile multi band parametric EQ on my RME ADIpro2 to utilize. I mainly use it for a master DAC for all my digital sources but without the EQ turned on.
You can also combine with speaker level passive filter if it’s attenuation only. Shelving filters and notches are good this way.
If your 410s are noisy there’e either something wrong with em or the source of noise is your power.
@mayhem13 Nothing wrong with my DN410s. They're completely re-capped and have A-series signetics 5532s throughout with wide band, low noise regs. They're just a little too hissy for my liking inserted between pre and power amp. I have ultra quiet JC2 and JC5. These are known to be excellent in terms of every aspect of accuracy and noise. I don't want anything between those two which aren't as good in terms of SN ratio. DN410s aren't bad, just not in the same league performance wise.
is there any drop in replacement for TL072 which is audibly better?
some say tle2072 has lower distortion but often its reported that other op amps give better improvement in sound
google puts out this
TL072 Equivalent ICs include LM358, NE5532, OPA827, LT1972, and ADA4610-2.2
some say tle2072 has lower distortion but often its reported that other op amps give better improvement in sound
google puts out this
TL072 Equivalent ICs include LM358, NE5532, OPA827, LT1972, and ADA4610-2.2
Look for audio grade dual JFET opamps if your application used the TL072 for its JFET input. NE5532 is quite good sounding but BJT input I think. OPA1642 is a superb sounding JFET input with a nice natural sound. Try it.
The NE5532 is bjt input. The resistor values around the feedback and ground from input legs need to be lower for best noise performance and low offset. Fet input op amps like higher resistance values for best SNR. Not as many choices in the FET category which can equal the NE5532 or LM4562 type