Full Range EQ

[andynor]

Just have a look at / post the impedance curve of the driver and you’ll see if the peak is relevant to handle with your current drivers or not.

 

[Nelson Pass]

Here's some more useful information about parts to fit those boards, all at Digikey:

RCA connector, PC mount RED: CP-1419-ND and GREEN: CP1423-ND

DC power supply: Triad WSU240-0500-13 Digikey # 237-1459-ND

Power input jack: CP-037B-ND

100K Potentiometer: Bourns 3386P-1-104LF-ND

Use any Electrolytic caps you like - minimum voltage is 25V, I used Elna 10uF output caps

Film caps have 5mm (0.2 lead spacing. I use Wima polypropylenes MKP2, FKP2

Film resistors - Vishay SFR25 type

 

[peppennino]

there is no voltage gain per se, main cell being buiffer

Hump and Bump are adjustable in circuit

Sorry, I intended a volume pot in order to use it as preamplifier

 

[andynor]

You can, but put it in front of the circuit and not in the midst of it, ref other variants (B1, etc). R3 makes an RC circuit, potting that would mess the EQ all up.

 

[Speedysteve7]

Yea, i think that you are on to something here.

Wether i am using all digital DSP processing as in high end car audio builds, or all analog EQ in home audio, or all digital DSP EQ adjustments as in home cinema setup:

Less is always more. Always!

Less BS is simply always purely, scientifically, and clearly less BS in your system.

Get everything tuned. The room, the crossovers, the placements. The enclosures.

And then, only then: Lightly EQ. Always aim to subtract, try always to avoid boost.

Because boost will always strain the chain.

Took the words right out of my mouth, As Meatloaf would say🙂

Got it down to a precious few cuts 30Hz, 78Hz, 115Hz to fix room modes from the powerful tapped horns.

The rest is as god intended, EQ free, open and glorious

 

[peppennino]

Would a 10K log pot be ok at input for volume control? I don't need a voltage gain since the power amp will be a little Moth Stereo and this board already has a buffer at putput.
Can I swich R3 to a 10K res in series with a 10K pot in oder to be able to vary from +3 to +6dB the bass bump?
Thanks

ok, I retry to write in a less poor English
So, I'd like to use it with OB fullrange spks with a Moth as power amp.
It has very high sensitivity, so I don't need voltage gain.
Since this circuit has no voltage gain but a buffer at output, I thought it was possible to ADD before the board a simple 10K log dual pot.
I do know that R3 is part of the RC filter, since it allows -changing it- to vary the bass EQ. As I need somethig between +3db (22K) and +6dB (10K) I asked if it is possible to use a 10K res together to a 10K pot in series in order to allow an easy regulation "on the fly".
Thanks again

 

[Nelson Pass]

The answer is you can do that, it should work fine. I think I would recommend a 25K pot
in series with R3 at 10K which will give you more range yet, and the mid point of the pot
would be close to stock value.

 

[andynor]

ok, I retry to write in a less poor English
So, I'd like to use it with OB fullrange spks with a Moth as power amp.
It has very high sensitivity, so I don't need voltage gain.
Since this circuit has no voltage gain but a buffer at output, I thought it was possible to ADD before the board a simple 10K log dual pot.
I do know that R3 is part of the RC filter, since it allows -changing it- to vary the bass EQ. As I need somethig between +3db (22K) and +6dB (10K) I asked if it is possible to use a 10K res together to a 10K pot in series in order to allow an easy regulation "on the fly".
Thanks again

Sorry Vinz, I didn’t realize there were two questions there. As usual you got it right the first time 🍷

 

[MEPER]

I think for me this circuit could work pretty well in front of a dedicated amp driving the 15" woofer (+passive cross over) in my OB speakers.
Then I would disable the HF part (assume this is done by not installing any of the HF parts and then make R4 a "short"?.
A circuit that starts to amplify around 40 - 45 Hz and down to 20 Hz would work for me. I can read that this should be possible.
At least I have ordered some circuit bords + components

 

[Mark Johnson]

Nelson gave instructions, about how to simulate the circuit (or your own personal variations of it), using MicroCap, in the .pdf article. Try it out and see whether you get pleasing results.

 

[peppennino]

The answer is you can do that, it should work fine. I think I would recommend a 25K pot
in series with R3 at 10K which will give you more range yet, and the mid point of the pot
would be close to stock value.

Many thanks!! 🙏 🍻

 

[MEPER]

Nelson gave instructions, about how to simulate the circuit (or your own personal variations of it), using MicroCap, in the .pdf article. Try it out and see whether you get pleasing results.

Yes, I will print out the article and read it in more detail. It will be a future project.
I also need to find out if circuit is best to insert after line-output or after preamp (I need some voltage gain with current power amp).
It would be practical to built it into same chassis as the preamp so they share same PSU and less external connections.
If a gain stage could be added "this" could be the preamp. Then it would be like a pre with "preset" tone-control.
Many possibilities for DIY-tweaks. Maybe some would like to use 2SK170 insted of J113.......who knows.....

 

[wrath]

I wonder if J112 will work (with 20R in series). Got bucket of them...

 

[triode_al]

Here is my quick simulation.
There are fancy ways to make variables like Nelson describes, but that is beyond my stock of tricks.
The J112 is 25mdB less gain (slightly higher internal resistance...)
You can of course also use an EF86 there and then you need the R9>500Ω. but this is the solid-state department of course

 

[grataku]

I when to the store today for some other stuff and noticed the kit has evidently already come and gone.
Is there an ETA for more kits?

 

[Nelson Pass]

PCBs shipped today.should be here in a week.

 

[WBS]

I don't have an ETA. However I suggest you click the "Notify When Available" button to be first in line when they reappear.

Ha! You beat me to the draw Nelson!

 

[Nelson Pass]

Yes J112 will work. Resistor should be set for around 10 ma bias.

 

[stocktrader200]

This would work as a loudness contour with a 6db gain stage right after it.

 

[stretchneck]

$150 amp, $10k speakers. I know the amps good. Lots of really decent FR drivers for MUCH less, particuarily if you diy the boxes.

View attachment 1175685

dave

F8 neo nowadays? Moved on from the Magnus which is a single cone whizzer?