[-Richard-]

"I think I would start with 12 ohm resistor and a 0.4 mH aircoil. Such an arrangement will gradually lower frequency response from 1 kHz to about 5 kHz. The effect will be like - 1 dB at 1 kHz and - 6 dB at 5 kHz it will then flatten out and sink the rest of the frequencies from 5 kHz and upwards with about - 7 dB. I think that will fit the actual Dayton response quite well and probably kill the heat. At least it will not cost a fortune to test. If the effect is considered too small complementing the coil with another 0.4 mH unit in series could be a further step.
I think all considered 12 ohm - 0.4 mH combo is preferred to my earlier calculation."

This was Erling's (moniker, Scorpion) suggestion during our email correspondence together quite a few weeks ago. I ordered the parts from Parts Express and hooked them up as he suggested:

"Yes, the inductor and resistor should be connected parallel with each other in the positive speaker lead. However I would place the combination in front of a High-Pass capacitor not to affect the crossover frequency."

He tempered this suggestion with this sage observation:

"This BSC (Baffle Step Correction) filter is of course a compromise. There will be some spillover around  3-4 kHz that ideally should be taken down a bit more. But really you would need a proper notch-filter to do that passively. The best thing would as perhaps you are on to, get a digital filter and do it that way."

So how does it sound? I can now leave the treble control of my re-circuited Heathkit (EL84's hooked up in Triode) to its full "on" position... at least most of the time. Before I had to turn it down... even quite a bit on some not-so-well-recorded music where the high frequencies sounded "hot" on the recording to begin with... which the Dayton Audio PS220-8 8" Point Source Full-Range Neo driver in its original form only exaggerated... given its high-rise (not flat) frequency curve in that area.

However, as Erling suggests, it is not a perfect solution... at least in my set-up. I really need to change the source of the digital signal to compliment Erling's BSC... I am seriously considering either the current Apple Mac Mini which sells for $600, or a current 13" Mac-Book Pro as a server for ripped files. Everyone I seem to know in the audio field is using one or the other (or if they have really deep pockets they have a dedicated "audio" server that does the same thing for much more money). That could bring a little more resolution to the top end and so "finish" the work of Erling's BSC suggestion.

But on many recordings the sound though my OB's is now superb... especially given the sound characteristics of my EL 84 integrated stereo in combination with the cheap Pioneer "universal" CD player I am currently using (not the most refined). On jazz, vocals and many small ensemble classical music CD's... the sound is fantastic. I am still not entirely satisfied with some violin ensembles that are not well-recorded. I am investigating a different amp as well as an apple mac for a music server.

Kudos to Erling... not only is he a very astute and well-intentioned gentleman... but he is a constant source of audio wisdom and very well-informed suggestions that make our group here on the OB Audiocircle forum such an incredible successful and knowledge-laden resource for everyone and anyone, who is interested in getting involved in the DIY Open Baffle experience.

And Erling was traveling in Australia while our correspondence went back and forth over several days. To say I appreciate Erling's advice and suggestions could never capture my feelings of profound respect and deepest admiration for his generosity and willingness to help. It was Erling's early suggestions that allowed me to join the Eminence 15A driver to my then B200's to complete the frequency range and thereby allow me to enjoy a full-musical experience with my OB's.

Thanks Erling. You are a gem.

With Warmest Regards ~ Richard

[Bob in St. Louis]

It's a wonderful community, filled with great people. You and Erling are two of them, for sure. 
Well done Erling.

Bob

[scorpion]

Given that there is some interest in the Decware version of this Dayton PS-220-8 speaker in a thread now (Sep 1st 2012) I tried to refine my BSC with a further Notch filter.
No more components in the signal path but the previous 0.4 mH inductor and 12 ohm resistor. Instead a parallel notch as pictured here:



Proposed PE components: 1.0 mH Jantzen inductor part nr: 255-100, 2 uF Dayton capacitor part nr: 027-414 and a 6 ohm resistor part nr 004-6.
Ca US $ 13 per channel.

The circuit is based on the published frequency response in the Specification sheet. I would think that this should lead to as close a correction for the speaker as is possible with passive components
to achieve a flat response.

/Erling

[scorpion]

By a very strange coincidence the German Klang + Ton DIY magazine presents a bassreflex speaker with the Dayton PS-220-8 in its September number.
The constructors choose the same path as I in their correction of the frequency response a BSC and a Notch filter. Contrasting my approach
they choose to put the notch in the signal path with paralleled inductor, capacitor and resistor. As I simulated my circuit I also did so with the German constructors':

First the effect of the Klang + Ton circuit as simulated:



Then the simulation of my circuit:



Please observe the difference in scale.

The Germans have worked with real units, I made my circuit from the published Specification Sheet.

And last, to please Richard, Klang + Ton did think the the Dayton speaker sound better with a Tube amp. 

/Erling

[Gothover]

Very nice, I have been wanting to try this driver.

Thanks, Dave

[-Richard-]

Hi Erling ~

You have accomplished the magic once again!!!! Thank you for your kindness and help with putting the finishing touches on your already invaluable work with taming the top end of the Dayton PS-220-8 neo drivers.

I am studying the excellent schematic you published for us... since I have never had the opportunity to implement a notch filter (or the BSC filter before you were so kind to share that information with me and everyone interested in using the Dayton driver) I will need to find a photo of what one actually looks like.

Thanks also for providing the actual value and parts numbers for us... that is incredibly helpful... along with the schematic, you have helped immeasurably to bring the cheap, yet classically designed Dayton drivers, as close to perfection as we can reasonably expect.

"And last, to please Richard, Klang + Ton did think the the Dayton speaker sound better with a Tube amp". Very interesting Erling! Strangely, right now I am using a cheap ($500) class D amplifier that I will be soon writing about... this Class D amplifier along with a simple tube preamplifier sound incredible on the Dayton's. I actually prefer it to the all-tube amplifier I have been using. Extraordinarily clean and clear.

However, I feel certain the addition of the notch filter you are suggesting for us will only help to relax the little bit of "shout" that can still be heard when voices, for example, end at a peak pitch in the song. With the new class D amplifier that peak is heard as a sudden unnatural "overshooting" of the voices natural range.

I have had the little light-weight class D amplifier in my system for less than 3 weeks now so it is still breaking in... without the tube preamplifier it is a little artificial sounding... with the tube preamplifier it sounds like a hugely expensive mega-buck Single Ended Triode tube amplifier on steroids... only clearer and cleaner. This sound is what tube amplifier designers spend years trying to achieve. To be able to get away from spending $500 and higher for a pair of expensive tubes that one prays will last is a gift from the gods.

Again... thanks so much Erling, for your thoughtful and skillful sharing of what we can do to tame these amazingly inexpensive drivers that really do deliver the sonic goods with the help of your modeling and filter suggestions.

I am truly impressed how close your suggestions are to the Klang + Ton circuit. I will share with everyone what I hear once I get the notch filter in place on the Dayton drivers. With your help, these drivers can now be referred to as "giant killers".

With Warmest Friendship ~ -Richard-

[doug s.]

hi erling,

i am curious - based upon your observations and simulated measurements, which would you choose, and why?  it appears that your filter is a bit milder.  do you think this driver would benefit from a more extreme filter like the k+t?

also, how would you think this drive would work in something like an oris horn, and would it still benefit from a filter?

thanks,

doug s.

[scorpion]

Doug,

Really someone more neutral should answer to your question.

But, I think I would have chosen my own circuit.
1st: No components in the signal path for the notch filter.
2nd: I think my circuit is more appropiate in the 200 - 2000 Hz region not taking away more than is needed.  It is a bit harder to judge the notch performance as such,
but on the whole I would think my circuit is a bit more balanced over the whole frequency range. Now I have had access to three different measurements of the unit, the Dayton spec sheet
and the German Diy Magazines: Klang + Ton and Hobby HiFi. I was infact quite happy that Klang + Ton published their design, it really could prove that my attempt was not completly out of the blue.

I hope that Richard perhaps will build the circuit and report.

Regarding Oris horn I dare not have any opinion. I have very little experience with front loading midrange horns.

/Erling

[wushuliu]

FYI, there is also the Singularity design for this speaker by Curt Campbell, one of the speaker gurus at PE:

http://speakerdesignworks.com/Singularity_1.html

[doug s.]

hi erling,

thanks for your reply,  i wanted your biased opinion!     having read your prior postings, i believe you would present a fair ewaluation, regardless of your biases.  your comment:

"...I think my circuit is more appropiate in the 200 - 2000 Hz region not taking away more than is needed.  It is a bit harder to judge the notch performance as such, but on the whole I would think my circuit is a bit more balanced over the whole frequency range. ..."

is exactly what i was looking for - your opinion on the overall balance.  i believe if you thought the k+t would have a better balance, you would have stated such...

regarding my oris, it is in fact a full range horn, used from 150-300hz (depending on x-over) up to 20khz.  i was wondering if you had any experience w/something like this, and how this driver's performance might be affected in such an application.  (i presently have decware modified fostex fe206e drivers in use...)



best,

doug s.

[Gothover]

I have tried the Dayton in several configurations, so far I am enjoying the benefits of horn loading.

This is my DIY Monaco horn Fc 200hz

I have built several prototypes of this horn, and so far it looks like it has good potential.

Dave