Very interesting write-up and measurements Bob. I like a warmer balance myself, so I can see why I like these things. Your description appears to coincide with my own experiences. Be interesting to see what different lengths etc would do, as you say.
I'll be putting the 126s into Frugels ultimately, but I'll be trying out a couple of other ideas first -I'm currently fooling around in MathCad to get the details finalised. Will let you know once I'm 100% happy.
I'll be putting the 126s into Frugels ultimately, but I'll be trying out a couple of other ideas first -I'm currently fooling around in MathCad to get the details finalised. Will let you know once I'm 100% happy.
No BSC, I don't even know what one is, I will have to do a search., ..The speaker measure's internaly @ W-7.25" D-10" T-17.5" port is 3"round x 4.5 deep in front below 167. Also a 2.75" x 3/4" brace @ 8.5" @ centered from top. Baffle is 1" thick. fe167e is not recessed, the port flare is recessed. I am new to DIY speakers but not other area's of DIY audio. I am done with all & any commercial offerings in speakers.................
A BSC circuit is a small passive circuit between amplifier and speaker driver that compensates for the 3-4db loss in output below a certain frequency caused by baffle diffraction. The specific frequency at which this occurs depends on the width of the front baffle.
Typically, a BSC circuit consists of an inductor and a resistor paralleled in the + lead to the driver, sometimes with a Zobel network (a capacitor and resistor in series connected between the + and - leads) added. Not to be confused with adding series resistance, which is sometimes done for various reasons, but usually to prevent an amplifier over-damping a low Q driver.
Typically, a BSC circuit consists of an inductor and a resistor paralleled in the + lead to the driver, sometimes with a Zobel network (a capacitor and resistor in series connected between the + and - leads) added. Not to be confused with adding series resistance, which is sometimes done for various reasons, but usually to prevent an amplifier over-damping a low Q driver.
Guys,
I must apologize, i missed the link to Bob's report and my post just after (now deleted) must have been a bit strange.
It is important to keep in mind that the FT-1600 incorporates a filter.
I look forward to the 2nd part of the report (hinted at in private mail from Bob) where a revisit of the filter yields some interesting results (from the plot Bob sent me i extrapolate/guess that the phase plugs and the filter tackle some of the same problems, and with phase plugs + filter some of the issues with the FE167 raw get compensated for twice).
dave
I must apologize, i missed the link to Bob's report and my post just after (now deleted) must have been a bit strange.
It is important to keep in mind that the FT-1600 incorporates a filter.
I look forward to the 2nd part of the report (hinted at in private mail from Bob) where a revisit of the filter yields some interesting results (from the plot Bob sent me i extrapolate/guess that the phase plugs and the filter tackle some of the same problems, and with phase plugs + filter some of the issues with the FE167 raw get compensated for twice).
dave
The FT-1600 speakers I used do indeed have a BSC filter. It is 1.5mH || 6 ohms. The effect of this filter is to set all frequencies above 200-300 Hz down something like 4 dB. This has no effect on the phase plug modification, as can be seen in the 0deg and 10deg plots. The level of these on-axis plots are unchanged out to 13kHz or so.
There are several things I need to look at:
1. Add a zobel to the filter. This will reduce the output at the high end, particularly 5kHz and up. This should reduce sibilance like the phase plugs do, but through a different mechanism. The zobel is electrical while the phase plugs are mechanical. What difference will that make on the sound?
2. Play with the size and shape of the phase plugs. Is there an optimum configuration for phase plugs in this driver?
3. Use phase plugs or electrical filters to reduce the highs, then add a tweeter. Will this give a better overall sound? Maybe go as far as a 2nd order XO around 6kHz or so.
Lots of possibilities.
Bob
There are several things I need to look at:
1. Add a zobel to the filter. This will reduce the output at the high end, particularly 5kHz and up. This should reduce sibilance like the phase plugs do, but through a different mechanism. The zobel is electrical while the phase plugs are mechanical. What difference will that make on the sound?
2. Play with the size and shape of the phase plugs. Is there an optimum configuration for phase plugs in this driver?
3. Use phase plugs or electrical filters to reduce the highs, then add a tweeter. Will this give a better overall sound? Maybe go as far as a 2nd order XO around 6kHz or so.
Lots of possibilities.
Bob
a report back on fe167e w/ phase plugs..
I installed Dave's plugs in my fe167e's in small BR cabs, I was waiting for my stands to be done so I could try in bedroom system, but couldn't wait. Put them in main, on very high end DIY stands. I can say this........ shout is reduced ALOT.!!!!!!! imaging is better & more real than ever, bottom is supported by a pair of active class D subs set half hazardly aroubd 100hz or so, this is wher they shine,....if you bing a good quck sub set high on these they just do every thing wonderfull, bottom is tighter with or without subs, strange........, but very audible, not more bass or slam just more REAL bass & very tight & very fast, faster than before, vocals, are less tipped & shouty....actually alot less tipped & shouty..locating these speakers now is impossible..........Ahhhhhhhhhhhh the pleasant sound of natural highs & none of the over the top compression crap!!!!!!!!!I do NOT run a BSC & feel no need, but might try it some day for the heck of it. also now much smother than before.....for the $ the plugs installed can't be beat, be carefully on the surgery of dust caps,have someone else do it if your the shakey type.........*s*. My main speakers are in the bedroom for now & just might stay there.... a very REAL possibility.. Not pimpin for Dave, don't even know the guy, just a very worth while mod on fe167e's.......
J & G
I installed Dave's plugs in my fe167e's in small BR cabs, I was waiting for my stands to be done so I could try in bedroom system, but couldn't wait. Put them in main, on very high end DIY stands. I can say this........ shout is reduced ALOT.!!!!!!! imaging is better & more real than ever, bottom is supported by a pair of active class D subs set half hazardly aroubd 100hz or so, this is wher they shine,....if you bing a good quck sub set high on these they just do every thing wonderfull, bottom is tighter with or without subs, strange........, but very audible, not more bass or slam just more REAL bass & very tight & very fast, faster than before, vocals, are less tipped & shouty....actually alot less tipped & shouty..locating these speakers now is impossible..........Ahhhhhhhhhhhh the pleasant sound of natural highs & none of the over the top compression crap!!!!!!!!!I do NOT run a BSC & feel no need, but might try it some day for the heck of it. also now much smother than before.....for the $ the plugs installed can't be beat, be carefully on the surgery of dust caps,have someone else do it if your the shakey type.........*s*. My main speakers are in the bedroom for now & just might stay there.... a very REAL possibility.. Not pimpin for Dave, don't even know the guy, just a very worth while mod on fe167e's.......
J & G
Bob Brines said:
A few questions Bob( bear in mind that that I haven't read all your listening report) ;
-what type of amp are you using for listening/measuring purposes?
-have you listened without BSC after adding the phase plugs?
- ever experimented with cone treatment?
disclosure:
I've been closely associated with Dave for the past several years, and have participated in the design process of several of the speaker enclosures posted on his site, and constructed more than a few of the prototypes shown.
While it's hard to play the DIY hobby for long without establishing some strong personal opinions, I try to keep my forum posts as objective as possible.
However, catch me at a trade show or "geekfest" after a long day and a few wobbly-pops and the guard might slip a little
chrisb said:
For listening, I use a Yamaha HT receiver and a 6BX7 PP amp. For measuring, I use a Sanyo chip amp salvaged from a pair of computer speakers and a Beringer EMC8000 mic, but it really doesn't make any difference what amp I use since SoundEasy zeros out the amp FR anyway.
Well, no, but as you can see from the before/after plots, the phase plugs make not difference below 2kHz, so BSC is a mute point. the top/bottom balance is going to have to be addressed with either a BSC step filter or DSP EQ regardless of whether the phas plugs ar installed or not.
No, and I should. I suspect that the 2kHz peak that most full-rangers have might be fixable with cone doping similar to what Dave is doing with the 126/127's.
Just in case anyone missed it, my final impression of the phase plug mod to the FE167E's in my FT-1600 cabinet is that the phase plugs soften the sound, reduce sibulance and give the speakers a somewhat warm sound. I just received a personal email from one of my customers that states the same opinion. It's a good mod and I endorse the Planet-10 phase plugs.
Bob
Shapes and sizes
I made the first attempt at this plug. I based it on an extension of the plug I used for the fe103. That design was arrived at by listening to various plug shapes and sizes. A bit teadious but it worked.
If someone is willing to do the testing I am will to make a few prototypes in an attempt to optimise the shape.
I made the first attempt at this plug. I based it on an extension of the plug I used for the fe103. That design was arrived at by listening to various plug shapes and sizes. A bit teadious but it worked.
If someone is willing to do the testing I am will to make a few prototypes in an attempt to optimise the shape.
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