Full Range EQ

Jump to Latest
#284
Power supply is 24v. RCRC reduces it just a bit. I don't have any input on reasonable substitutions, but the necessary transistors come with the board.

I opted to finish mine "breadboard" style. I added little rubber feet and it will sit behind my preamp.
IMG_00298.JPG
 
  • Like
Reactions: sam08861 and WBS
#285
After a few days of listening, these little wonder boards are awesome! I've been using my TangBand 1772 speakers in a 40L vented enclosure for several years. I've been fiddling with an external speaker-level crossover on and off during this time and have made some improvements to the rising top end and the enormous hump from 7-10k, but it never sounded quite right to me. With Nelson's EQ board, I was able to dial things in with much more precision, add a little bass, and now I have a flatter response plot without the nasty 7-10k hump.

This had definitely increased my enjoyment of these speakers! Thank you, Nelson!
 
  • Like
Reactions: otherwillsmith, bigaudioscotto, G600 and 1 other person
#286
Eric said:
Power supply is 24v. RCRC reduces it just a bit.
Click to expand...
Couple of Q's (for any reader)...

First, the schematic in Nelson's opening post lists supply voltage at 47.5 - I assume that's easily drawn from the plus & minus of a 24v bipolar supply?

Second, I imagine wanting to be able to accommodate different drivers. I have one full-range pair of drivers that definitely shout, and I'm also breaking in some new ones that shouldn't need adjustment to the highs. Is there a simple defeat to the high filter, or would a 'neutral' set of RC parts be best? Many thanks in advance for your suggestions.
 
#289
The FullRange EQ is very adaptable if you want/need low range boost and/or mid-to-treble range limitation -- as well expressed in Nelson's article. Lots of this and or that choices. It's cheap and easy to assemble. I think almost everyone would be surprised just trying one without modification even if they have good sized mid-woofers and a fair bit of treble extension from their tweeters all in conventional boxes with decent crossovers. I see help to systems where optimum speaker placement is not possible, bright rooms, and poor recordings of great music, not to mention the more obvious cases. Full Range drivers and open-baffle designs. Sure, they are tone controls, but they are active not passive with those limitations, and crystal clear.

Optimization will need some cap and resistor changes.

Skip
 
  • Like
Reactions: bloozestringer
#291
That is mostly a question above my circuitry analysis knowledge level, but the design has fixed filter order built into its design. You can move the center of the boost/cut filters and flatten or increase the amount of the boost/cut. To control the 20khz level much, the center of the cut would have to be fairly high and you might not get what you want in the upper middle range. I would only mislead if I were to guess at ways to mod the design in any change to the circuit architecture.

Skip
 
#292
francolargo said:
For example, could one simply push the frequency band intended for upper midrange suppression up well above 20kHz? If so, what kind of values for C3 and C4 would accomplish this?
Click to expand...
Simple RC lowpass filter calculator says, for C=100pF and R=40k ohms, the -3dB cutoff is 40kHz. That would seem to do it, but for stability issues, etc. I don't have a Windows machine to install Micro-Cap... 🙁
 
#293
Skip Pack said:
The FullRange EQ is very adaptable if you want/need low range boost and/or mid-to-treble range limitation -- as well expressed in Nelson's article. Lots of this and or that choices. It's cheap and easy to assemble. I think almost everyone would be surprised just trying one without modification even if they have good sized mid-woofers and a fair bit of treble extension from their tweeters all in conventional boxes with decent crossovers. I see help to systems where optimum speaker placement is not possible, bright rooms, and poor recordings of great music, not to mention the more obvious cases. Full Range drivers and open-baffle designs. Sure, they are tone controls, but they are active not passive with those limitations, and crystal clear.

Optimization will need some cap and resistor changes.

Skip
Click to expand...
Thanks Skip. I’ve not measured them in my room yet, but most the graphs I’ve seen show a big dip at 6.5Khz that probably could use correcting. Of course they drop like a rock after 10K, so some sort of tweeter from 8K up might help as well. There is definitely some potential there.
 
#294
I really look forward to incorporating these boards into my new 'small system' being constructed, and I'm trying to 'guesstimate' some starting values without running a simulator. A small request from those with experience using this circuit. In Nelson's intro to the board he presented the below graph, but the traces were not labeled. Clearly, curve B is C1,2 = 0.1uF, and presumably C3,4 = 1 nF.
First question: Which of the two remaining cap values go with curve A vs curve C?
Second question: The "reference curve" as presented (in Nelson's intro) supposedly used C3,4 = 470pF and its treble minimum was at 4kHz. I believe that's inconsistent with the below graph, in which the lowest C3,4 value was 500pF. If the C3,4 value of 1nF produced curve B with a filter minimum at about 4.6kHz, then aren't these treble curves - with minima from ~2.2kHz to 10kHz - about an octave off? [We see that the frequency shift produced by changing R5+P1 is significant, but could that explain the discrepancy?]

Many thanks for any insights or suggestions!

Frank

curves.jpg
 
Last edited:
#296
I changed my listening room from the SLOB's to the Lowther Medallian 2 cabinets with PM2A drivers. Threshold FET 10 HL preamp with a EUVL J2 clone amplifier. The Full Range EQ I built to reduce the 7K Lowther "shout". What an improvement, fuller sound, easy to listen to and has the wife's approval!

Thank you Nelson! This project just saved me from buyers remorse with the Lowthers.
 

Attachments

  • IMG_0263.jpg
    IMG_0263.jpg
    565.5 KB · Views: 113
  • Like
Reactions: otherwillsmith
#299
Perhaps I’ve missed something but is there a place where i can get the correct curves/component values for different drivers Nelson mentioned? I don’t currently have access to a windows machine to run microcap so I tried downloading a similar(?) program for Mac called KiCAD but I can’t get it to open the zipped file so it might not be compatible or I might be doing it wrong

I need it for a pair of FA22rcz - which have been mentioned a couple of times in the thread - in an approx 60L br cabinet if anyone can help. Thanks
 
You must log in or register to reply here.
Top Bottom