Modifying Realistic T-100's to Pioneer B20 Full Rangers

greenmark59

Can ya' hear that?
Well here's the finished project that I started Friday 8/27/10 and I completed on Saturday 8/28/10 (fairly simple; the way I like them). I bought these working Realistic T-100 speakers from a thrift store about 2 weeks ago for $30 and they sounded all right especially after I replaced the Radio Shack tweeter with a AR18 tweeter, but I just knew the cabinets were destined for something better. So once I heard that Parts Express had the infamous Pioneer B20FU20 full range driver on sale for ONLY $19, I took the plunge and took off a long lunch and drove to Parts Express (25 miles away) and bought the needed items.

Used the B20FU20-51FW and the Goldwood GT-1005 wide dispersion piezo tweeter with a 20 ohm resistor across it's terminals and a 1 uF capacitor before the L-pad. The big blond 10" wood circle covering the 2nd woofer hole is a 99 cent piece from Hobby Lobby. The (2) port tubes are 2 1/16" x 5". The internal dimensions of the Realistic T-100 cabinet is 34.25" x 10.25" x 11.5" for 2.34 cubic ft or 66 liters. The configuration I'm using will give me 34 Hz according to WinISD.

185516d1282821495-bofu-sale-screenhunter_01-aug.-26-07.15.jpg


Modifications still to do are: reduce the size of the the BIG blond circles and then stain them, simple stands at bottom of speaker to raise B20 height about 7" (closer to ear height when listening). Try to restore cabinet wood. Put felt around the B20 speaker frame legs. Look into installing phase plugs. Install different terminal plates on the rear of cabinet (Radio Shack has their terminal at the BOTTOM of the speaker - yuck!!!).

I have been playing them for over 48 hours and will continue to do so for about 72 total hours to break-in the speakers.

First impressions are that they sound Sweeeeeetttttt!!!!! :thmbsp:

I am already a full ranger speaker lover (RS 40-1354 drivers in Bob Brines designed TL cabinets) and I got to tell you these 8" drivers for $19 really have a lot more bass than other smaller full range speakers. Just as a sound test for deep bass, I play the first song of the Titanic soundtrack and there is a deep kettle drum sound played numerous times and if I can "feel" this bass (which I did with the B20's) I am fairly satisfied with the bass that I will get out of these speakers. I also played Pat Metheny & Charlie Haden's "Beyond The Missouri Sky" album and this album has plenty of bass notes and as I listened I could to easily hear them and they seemed to not be muffled (like they were previously with the T-100 woofers).

I gotta say that with the right cabinet these B20's can really "sing" and everyone is right, you just want to keep listening and listening and bringing out old CDs and records to listen to them over again and it's like rediscovering the music on them. The sound stage both horizontally and vertically is pretty good. I have tried running them with my 8 watt T-amp and my Dayton APA150 150W Power Amplifier with the more powerful Dayton amp giving the speakers more relaxed headroom to play. The T amp sounds very nice at lower volumes, but is strained at larger volumes. I am going to purchase a more powerful T amp and I think it will be more synergistic with the B20. I typically am not too optimistic about most reviews of speakers until I hear them myself, but in all honesty for less then $100-$150/pair TOTAL these have got to be ONE of the best speaker bargains around. I spent $30 for cabinets, $52 for drivers, caps, resistors,tubes and another $5-10 on miscellaneous stuff.

All in all a VERY SATISFYING project and some very, very good sounding speakers. :music:
 

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Nice, I just picked up a pair of these on sale as well...

I have been playing around using them as an open baffle midrange with helper woofer and tweeter. Results are promising but honestly I will probably just end up using them full(ish) range with a helper tweeter as you have done. I don't know if I am going to go the sealed box route or try out the half chang cabinet. probably sealed as the half chang is a little tall for me visually.

I'm thinking your hobby lobby circle plug may be acting as a passive radiator to some extent, especially if it is thin.
 
Nice! I'm a big fan of the B20s...

They match well with the Pioneer Horn Tweeter also.

http://www.parts-express.com/pe/showdetl.cfm?Partnumber=270-050

Here's a tip you may want to try: Pack modeling clay around the throat of the tweeter.

Thanks for the recommendation about the Pioneer Horn Tweeter. I just found out by playing frequency tests on my different speakers that I am only able to really hear up to 16 kHz. I guess that can happen with age. But since most music is played in the mid-range frequencies, I get the benefits of the B20. :yes:

So when you say "Pack modeling clay around the throat of the tweeter" I am assuming you mean on the backside of the tweeter - correct? What exactly does this mod do for the tweeter?
 
I'm thinking your hobby lobby circle plug may be acting as a passive radiator to some extent, especially if it is thin.

Yeah I thought so also, but when I play "bass" oriented music and touch the "plug" there isn't any more noticeable vibration than what can be felt from the cabinet itself (well slightly more). They are mounted through the center and use a toggle bolt with a 8" piece of wood strip to hold the circle in tension against the cabinet wall. I guess if I glued some "weight" to the circle that this would make it less likely to act as a passive radiator. Good idea!!!
 
With the toggle bolt placing the circle under tension it is probably not an issue.
I've gotten to the point in my speaker building career where I hate making boxes. I think I'm going to go the same route and repurpose an older pair...
 
Bob Brines is going to design a TL box for these B20 speakers. Maybe can consider that if you are willing to wait. Look at post #15 in the following thread:

http://www.diyaudio.com/forums/full-range/172231-bofu-sale-2.html

thanks for posting that, that is good news...

I'll probably cobble something together in the interim so I can enjoy these. I'll let Bob do all of the grunt work on the modifications to the driver that he mentions in the thread and then just copy his successes!:yes:
 
So when you say "Pack modeling clay around the throat of the tweeter" I am assuming you mean on the backside of the tweeter - correct? What exactly does this mod do for the tweeter?


Correct... The clay will take the 'plastic zing' sound out from the tweeter (if you think you hear a 'plastic zing' sound) :D
 
With the toggle bolt placing the circle under tension it is probably not an issue.
I've gotten to the point in my speaker building career where I hate making boxes. I think I'm going to go the same route and repurpose an older pair...

After doing some research into the B20, it is a very forgiving driver when it comes to using different boxes. And since it is an 8" driver it can potentially fit plenty of different boxes. Hey I just remembered that I have (3) AR-4x speakers that may just work as sealed boxes for the B20. I could sell the woofers and buy the B20's. Heresy?

EDIT: AR-4x boxes too small - not smooth enough and will have a "bass bump" around 100-120 Hz
 
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I ran some generated sine frequencies through the converted T-100's and could definitely tell (at least by my finely tuned ear) that the speakers do go down to about 36-37 Hz before they drop off in volume. Pretty amazing when considering it's just a full range 8" driver. :)

Wish I had some more sophisticated measuring instruments besides my ears to see what the real frequency curve was on these speakers.
 
Bob Brines is going to design a TL box for these B20 speakers. Maybe can consider that if you are willing to wait. Look at post #15 in the following thread:

http://www.diyaudio.com/forums/full-range/172231-bofu-sale-2.html

Just a head's up, but I believe that there's also a a couple of back loaded horn designs on Dave Duglos' Planet10 site that were designed to work with those Pioneers. It's one of the "Chang" family, it may be a "Half Chang" or a version of the "Curvy Changs" or both.

Bob Brine is a pretty good designer, but these have gotten good reviews by several builders, so this may offer a viable alternative and it never hurts to have choices and options anyway.

Good Luck on your project!

Best Regards,
TerryO
 
This is very interesting - thank you. I have a pair of T-100's that I've stored away for a future project. I thought about e-waving them but this looks pretty interesting. Could a passive radiator be used in lieu of adding the ports? I ask because I have a PR in there now along with a 8" 8-ohm woofer. I don't have a way of measuring the frequency response but they seem to put out pretty good bass with the PR.
 
This is very interesting - thank you. I have a pair of T-100's that I've stored away for a future project. I thought about e-waving them but this looks pretty interesting. Could a passive radiator be used in lieu of adding the ports? I ask because I have a PR in there now along with a 8" 8-ohm woofer. I don't have a way of measuring the frequency response but they seem to put out pretty good bass with the PR.

Got any pics of your speaker setup?

Yes, you can add a PR in lieu of the ports. You will need some type of software to help determine how to use the PR and what weight to add to it to make it compliant. I found this article/software here and may just attempt this myself. :scratch2:

http://techtalk.parts-express.com/showthread.php?t=209863
 
Do they sound better than they did stock? Seems the T100 is a good speaker and i like the mid and bass but the tweeter needs replaced IMHO. I can't see how a $20 FR driver would be better sounding than the stock config. :scratch2:
 
Here's a tip you may want to try: Pack modeling clay around the throat of the tweeter.


Tip #2 :D this time for the B20

Mix 50/50 (water/mod podge) and apply two coats to the outside cone. 24hr drying time between coats. *DO NOT* coat the foam surround or whizzer with this mixture.

For the inner whizzer cone: Apply three coats of Dammar Varnish; 24hr drying time between coats.

:thmbsp:
 
Do they sound better than they did stock? Seems the T100 is a good speaker and i like the mid and bass but the tweeter needs replaced IMHO. I can't see how a $20 FR driver would be better sounding than the stock config. :scratch2:

IMHO the T100 did need a tweeter change and I upgraded mine to a AR18x tweeter and it did make a BIG difference, but the T100 just had this veiled and muffled sound to it. The bass wasn't bad, but to my ears there is no comparison that the mid-range on the B20 is far better. The sound stage of the B20 is also fair superior. These speakers virtually disappear when sitting in front listening to them. You cannot really hear the music coming directly from the speakers because the notes actually "float" within the sound stage before you. At first it's kinda' freaky because you may not be used to this and after awhile you start playing this game of listening to individuals playing their instruments and the singers position on the stage. This is really evident when listening to live recordings. I was listening last night to "Tom Jones: Live at Caesar's Palace" and you can literally sense Tom moving about the stage both width and depth. It makes if fun to listen to music. :music:

Again this is my 2 cents worth.
 
No pics now but I may be able to get some tonight.

The PR's are from some old Polk Monitor speakers - not sure if they can be weight-modified. I think PE sells some though and last I checked they had a 8" model.


Got any pics of your speaker setup?

Yes, you can add a PR in lieu of the ports. You will need some type of software to help determine how to use the PR and what weight to add to it to make it compliant. I found this article/software here and may just attempt this myself. :scratch2:

http://techtalk.parts-express.com/showthread.php?t=209863
 
The original crossover of this speaker was just one capacitor and a variable resistor. So you just replaced each of these? What is the new crossover point?

IMHO the T100 did need a tweeter change and I upgraded mine to a AR18x tweeter and it did make a BIG difference, but the T100 just had this veiled and muffled sound to it. The bass wasn't bad, but to my ears there is no comparison that the mid-range on the B20 is far better. The sound stage of the B20 is also fair superior. These speakers virtually disappear when sitting in front listening to them. You cannot really hear the music coming directly from the speakers because the notes actually "float" within the sound stage before you. At first it's kinda' freaky because you may not be used to this and after awhile you start playing this game of listening to individuals playing their instruments and the singers position on the stage. This is really evident when listening to live recordings. I was listening last night to "Tom Jones: Live at Caesar's Palace" and you can literally sense Tom moving about the stage both width and depth. It makes if fun to listen to music. :music:

Again this is my 2 cents worth.
 
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