RBR-KIT, the “Recession Buster Reference” Kit, Pair

[fjhuerta]

I learned the hard way that is far better to just buy a cheap chip-amp / class-D kit (say, those offered by chipamp.com) or 41hz.com rather than buying a low powered "esoteric" tube amp.

As a matter of fact, I have 5 pretty nice tube amps, and my amp of choice is a Channel Islands solid state Class-D...

[WalkinPaul]

Hi Paul...

Welcome, congrats, and... she sounds like a keeper!! :T

Keep us posted and post some pics!

Jon

You are in for a treat I'm sure. Quality components and Jed's designs are always fantastic (I've built 2 of them now). Good luck with the build and be sure and post pics or they aren't real! (forum rules )

Thanks. I will definitely post some pics. Hopefully I won't be too embarrassed.

I have looked at all the great designs here and was trying to choose one to build. Friday I saw Jed's new design and the price was so good that I just had to try it. I will also need to find a suitable CC at some point.

I ordered the basic XO w/ port. At the moment I'm using a Bose center and a pair of Paradigm mini monitors that I picked up cheap, all driven by a Denon AVR-2802. I will be probably replacing all of this as time and money provides.

I am now contemplating what my cabinets will be made from. I know MDF would be best sonically, but I'm hesitant on doing the veneer myself, since I have never done it before. I would probably go with curly cherry, maple or maybe even an exotic. I'm looking into how to do this now. $

I am also considering using Baltic birch for the sides and using MDF for the baffles. Or a sandwiched cherry/mdf for the baffles with the cherry on the outside. $

I have an acquaintance that is a master furniture maker and has all the veneering tools that you can imagine. His work is absolutely beautiful. I may go talk with him and see what he says. I may just build them & pay him to do the veneer. I have a garage full of tools, so hopefully the cabinets won't be too much of a problem. I also build mandolins, guitars, and Arts&Crafts furniture too when I can find the time. $$.

On the other hand, I have a friend, (of a friend), that can do some amazing instrument finishes. I believe he worked for Fender for a while. I may go with something painted. Maybe he can paint the MDF to look like something exotic. $$$

So many choices, but that is a good thing and I'm definitively keeping the wife. She's been my world for over 19 years now. $$$$!!! (Just Kidding baby). :B

[Hdale85]

Veneering smaller cabinets like that shouldn't be too bad.

[Coconutout]

gentlemen im in trouble. im staying in china for 2 months. just found out earlier that i cannot access the enclosure plan info at http://www.clearwaveloudspeaker.com/RBR/buildRBR.html due to unreasonable chinese firewall. even when i try to bypss it with vtunnel or similar, i still can't see any pictures! please help me figure out the enclosure dimensions for ported version of the RBR kit- asap. because im going to a furniture factory tomorrow where i'll be able to get the enclosure made in birch ply... for free from my dad's partner thank god for chinese hospitality. their internets still horrible tho.

[PoorboyMike]

I hope this is OK to post. 8O If not, sorry in advance.

Image not available

[Coconutout]

thank you. that was a life saver. taking a careful look at the drawing for the first time i see that sealed is dramatically smaller than ported enclosure. this is a big plus in my current living space. i just might opt for sealed version if i can find out how much bass i would be losing over it and leave out the 2flares thats coming with the madisound ported enclosure kit- which btw im still trying to get the flange thickness of.

[Jed]

F3 sealed is just below 60hz. If you want bass go ported otherwise use a subwoofer to fill in the lower octaves.

[Jonasz]

Two quick questions: Does the SB-tweeter have a metal face plate? What's the total system sensitivity?

[JoshK]

This is the first I'm see of this kit. I am highly tempted. My wife rearranged my LR much to my chagrin* and so I am splitting my systems, HT and audio. A smaller 5" 2 way should do very nicely for movie/TV watching.

Madisound should have offered the kit in singles too so one could do 3 or 5 channels for HT.


(*edited by the spelling droid)

[JonMarsh]

With 4 dB BSC it would be about 80-81 dB/watt depending on your LF inductor choice (DCR losses); 5" woofers aren't known for high sensitivity! the tweeter has a plastic faceplate.

[tf1216]

Does anyone know if someone here or on the PE board will supply cabinets for these guys?

[Jed]

I think some guys are missing the page with the specs and design choices etc. I listed the sensitivity at 82db. The FR graph in the SS spec sheet shows about 85.5db, so minus 3.5-4dbs BSC we get around 82-81db.

The engineers of Scan Speak know that in order to get the bass extension you have to give up some sensitivity. My 60watt into 8ohm amplifier drives these to very loud levels, so I wouldn't recommend a tiny amplifier with these, but I also wouldn't worry about whether or not they can play loud.

http://www.clearwaveloudspeaker.com/RBR/infoRBR.html

[Jed]

Does anyone know if someone here or on the PE board will supply cabinets for these guys?

Even the 20L MTM PE cabinet might work fine. Only 1/2" difference. The bump around 840hz will be a tiny bit worse though because the baffle is a little wider.

[Jed]

This is the first I'm see of this kit. I am highly tempted. My wife rearranged my LR much to my chagrin* and so I am splitting my systems, HT and audio. A smaller 5" 2 way should do very nicely for movie/TV watching.

Madisound should have offered the kit in singles too so one could do 3 or 5 channels for HT.


(*edited by the spelling droid)

Call them and see if you can buy 5. Or, you could always buy 3 pairs and sell the extra one. There is a guy over at another forum looking for 3 speakers, so he might take a single off your hands.

Jed

[Hdale85]

Might be a crime to not play music through these though

[Coconutout]

I think some guys are missing the page with the specs and design choices etc. I listed the sensitivity at 82db. The FR graph in the SS spec sheet shows about 85.5db, so minus 3.5-4dbs BSC we get around 82-81db.

The engineers of Scan Speak know that in order to get the bass extension you have to give up some sensitivity. My 60watt into 8ohm amplifier drives these to very loud levels, so I wouldn't recommend a tiny amplifier with these, but I also wouldn't worry about whether or not they can play loud.

http://www.clearwaveloudspeaker.com/RBR/infoRBR.html

so you wouldn't say it's an acceptable match to use this amp with the speakers? this is the system i have planned my budget with that i intend to keep for a very long time. should i not even bother with ported enclosure then and look for a sub instead if i want to still go ahead with the amp?

[DancesWithBeers]

so you wouldn't say it's an acceptable match to use this amp with the speakers? this is the system i have planned my budget with that i intend to keep for a very long time. should i not even bother with ported enclosure then and look for a sub instead if i want to still go ahead with the amp?

Here is what is said at Zaph Audio about the ZD5, which uses nearly the same driver that is used in this reference kit:

"With some of my designs, I post an add-on conjugate notch for impedance flattening. This might make a speaker friendlier to tube amps. This design however has a very low sensitivity and I recommend solid state amps only. Do not use this design with tube amps."

I think the same would apply to Jed's design. Is there any particular reason you don't just buy a used solid state amp with more power for less money on craigslist or ebay?

[Jed]

so you wouldn't say it's an acceptable match to use this amp with the speakers? this is the system i have planned my budget with that i intend to keep for a very long time. should i not even bother with ported enclosure then and look for a sub instead if i want to still go ahead with the amp?

That amp is only 13 watts so it'll be good for low volume listening only. I don't recommend amps I haven't heard before but the low wattage is probably not the best match.

[Coconutout]

Here is what is said at Zaph Audio about the ZD5, which uses nearly the same driver that is used in this reference kit:

"With some of my designs, I post an add-on conjugate notch for impedance flattening. This might make a speaker friendlier to tube amps. This design however has a very low sensitivity and I recommend solid state amps only. Do not use this design with tube amps."

I think the same would apply to Jed's design. Is there any particular reason you don't just buy a used solid state amp with more power for less money on craigslist or ebay?

i only got to enjoy a full tube setup for one day before my dog blew out the el84 by licking it. but just a single song was enough to blow ME away. it was a love at first note and i don't feel like trading its ultra delicious analog distortion for anything less... ok, maybe a mosfet amp but a good one would be just as expensive i imagine. im weighting in your opinion equally as heavly as jed's so the dilema has not been resolved...

[benchtester]

i only got to enjoy a full tube setup for one day before my dog blew out the el84 by licking it. but just a single song was enough to blow ME away. it was a love at first note and i don't feel like trading its ultra delicious analog distortion for anything less... ok, maybe a mosfet amp but a good one would be just as expensive i imagine. im weighting in your opinion equally as heavly as jed's so the dilema has not been resolved...

I googled the amp, but didn't find the output impedance. Do you know either the impedance or if there is enough negative feedback? I'm not an expert on tube amps, but it looks to me like the speaker's impedance varies enough that it wouldn't sound good with a high impedance tube amp. (Could be "fixed" like Zaph's projects.)

[Coconutout]

I googled the amp, but didn't find the output impedance. Do you know either the impedance or if there is enough negative feedback? I'm not an expert on tube amps, but it looks to me like the speaker's impedance varies enough that it wouldn't sound good with a high impedance tube amp. (Could be "fixed" like Zaph's projects.)

output impedance 4O/8O here all the numbers indicate its not a good match but im still tempted due to the low price i found this for on ebay and the fact that i have telefunkens to swap the tubes with. plus i'm not really much of a basshead... is it gonna sound plain bad?

[Jed]

To make the impedance more tube friendly add L4, R5, C5 across the binding posts. This levels the impedance to 6-8 ohms. It doesn't solve the lack of power issue.

[Coconutout]

thank you jed- a design advice from the creator himself means a lot to me. however from two reviews ive read about the mingda el84 amps state that they have no trouble driving low impedance speakers to full power. one reviewer had a pair with 82db other one just as low although the exact number i cannot recall. i'm gonna go ahead and order the ming-da with the result soon to be posted. this amp might be a real winner- tube amp with a separate power supply for $350

[Face]

It depends on how loud you listen and the size of your room. I use a 20wpc triode tube amp with 85db(ish) towers and I'm able to attain enough volume.

[benchtester]

thank you jed- a design advice from the creator himself means a lot to me. however from two reviews ive read about the mingda el84 amps state that they have no trouble driving low impedance speakers to full power. one reviewer had a pair with 82db other one just as low although the exact number i cannot recall. i'm gonna go ahead and order the ming-da with the result soon to be posted. this amp might be a real winner- tube amp with a separate power supply for $350

You may understand this well, but to clarify, Jed's modified crossover circuit above flattens the impedance curve in the midrange. So the frequency response should be more even with a high output impedance amplifier. You should plan on using it. But it would be fun and educational to try it with and without the impedance compensation network connected.

[CAAD]

What is involved in building a non-BSC version of this kit?

[Jed]

What is involved in building a non-BSC version of this kit?

How will the speakers be placed?

[CAAD]

In-wall, with the baffle flush with the wall surface.

[Jed]

In-wall, with the baffle flush with the wall surface.

I was hoping they would be mounted on wall because I could use the measurements that I have. In wall, I can give you a suggestion but no guarantees (although it'll be fairly close) because of the cabinet edge diffraction that was integrated into the original crossover.

[Jed]

Madisound should have offered the kit in singles too so one could do 3 or 5 channels for HT.


(*edited by the spelling droid)

I just got word they are doing this now, but you have to call or leave a note in the comment box of the order. Safest bet is to call them.

[CAAD]

I was hoping they would be mounted on wall because I could use the measurements that I have. In wall, I can give you a suggestion but no guarantees (although it'll be fairly close) because of the cabinet edge diffraction that was integrated into the original crossover.

With all the free time on your hands, what fun would it be if it was that easy?
'Close enough' is good enough for my application. These will be surrounds and I've got to go with ceiling-specific speakers for the rears, so the sound field won't be completely unified anyway.
Deep thanks and respect.

[Jed]

With all the free time on your hands, what fun would it be if it was that easy?
'Close enough' is good enough for my application. These will be surrounds and I've got to go with ceiling-specific speakers for the rears, so the sound field won't be completely unified anyway.
Deep thanks and respect.

I should be able to come up with a design for you around the 19th. I unfortunately left my laptop power cable at my sister's house, and I'm about 600 miles away. Before I left I was playing around with the design and it required a resistor change on the treble and unwinding the larger series inductor. Just remind me next week to get the files up.

[CAAD]

Thanks, man. No hurry, though. The wall is going to require some time consuming 'modification.'

[Jim85IROC]

Well, I just pulled the trigger on a set today. I've got a garage full of drivers that I don't have time to use, so what do I do? I buy more.

But... part of why I haven't touched a lot of those drivers is because I don't have the time to get good enough with Soundeasy to get useful measurements, design & build the filters, then rinse and repeat until I'm satisfied.

With these, I just need to build the boxes... which could still take months.

Anyway... yay. I'm excited. I'm still using my old, OLD Boston Acoustics T830 floorstanders, and as much as I like them, I'm definately looking forward to stepping up to a speaker of this caliber.

[NyxOne]

Hey! Know what ? I've just received my kit from Mad! They did a nice job with the packaging! From the look, I can tell that the box have been beaten pretty badly but everything inside is in perfect condition!

Those scanspeak woofer are really heavy for their size! I was also really impressed by the crossover, it's really large and heavy (I've the upgraded version)!

Now time to start building the enclosure!

This is going to be fun! :B

Chuck

[Jed]

Thanks, man. No hurry, though. The wall is going to require some time consuming 'modification.'

Hi,

I had some time and here is my recommendation. The gray curve is the original response. As you can see I boosted the frequencies above 200hz to give you a flatter response when these are mounted in a wall or on the wall. Without measuring the speaker in that environment this is more of a guess. However, I do think it'll work out well and you can unwind the main inductor and just buy a few extra resistors after you get your kit. Or, maybe you could get the guys at madisound to build it this way for you.

Jed

[JoshK]

I just got word they are doing this now, but you have to call or leave a note in the comment box of the order. Safest bet is to call them.

Thanks for the info!

[looneybomber]

* We are now on back-order for some of the Clarity Caps used in the crossover. The Clarity PX 9 mfd pictured in the woofer circuit will use a Solen Poly FastCap 9 mfd cap instead.*

* The Clarity SA 6.8 mfd used in the tweeter circuit for the standard crossover is also on back-order...Option 2 is to use Clarity PX 6.8 mfd & Clarity PX 12 mfd in this circuit. Price has been adjusted accordingly, select from Crossover drop down menu above when placing your order. *

Would the downgrade in caps have any sonic impact? I wouldn't think so, but I also don't have any experience with them.

[Face]

It shouldn't make a significant difference, though, it should be even more incentive to select the premium kit. CC ESA's are fantastic caps.

[ThomasW]

One would need to own some pretty $pendy electronics to hear the differences in those particular caps.

[CAAD]

Hi,

I had some time and here is my recommendation. The gray curve is the original response. As you can see I boosted the frequencies above 200hz to give you a flatter response when these are mounted in a wall or on the wall. Without measuring the speaker in that environment this is more of a guess. However, I do think it'll work out well and you can unwind the main inductor and just buy a few extra resistors after you get your kit. Or, maybe you could get the guys at madisound to build it this way for you.

Jed

Thanks! I'll give them a call.

[Jim85IROC]

* We are now on back-order for some of the Clarity Caps used in the crossover. The Clarity PX 9 mfd pictured in the woofer circuit will use a Solen Poly FastCap 9 mfd cap instead.*

* The Clarity SA 6.8 mfd used in the tweeter circuit for the standard crossover is also on back-order...Option 2 is to use Clarity PX 6.8 mfd & Clarity PX 12 mfd in this circuit. Price has been adjusted accordingly, select from Crossover drop down menu above when placing your order. *

Would the downgrade in caps have any sonic impact? I wouldn't think so, but I also don't have any experience with them.

I was thrilled to be able to save $25 just by substituting some overpriced poly caps for some less-overpriced poly caps.

[looneybomber]

I was thrilled to be able to save $25 just by substituting some overpriced poly caps for some less-overpriced poly caps.

That's a good point. And since I would power them with an AVR or using the AVR as a preamp to an XPA5 (possible future purchase) it likely wouldn't matter much.

[---k---]

I was thrilled to be able to save $25 just by substituting some overpriced poly caps for some less-overpriced poly caps.

That was my first thought (though I do have some room in my mind for Clarity Caps can sound better under the right conditions).

I'm having a real hard time resisting buying a pair of these to play with. The only thing holding me back is I have no place to put them, and I fearing a WMTMW in my future with all Scan Speak drivers.

This kit is just at a really really good price point. Well done Madisound!

[Dean100]

I'm having a real hard time resisting buying a pair of these to play with. The only thing holding me back is I have no place to put them, and I fearing a WMTMW in my future with all Scan Speak drivers.

This kit is just at a really really good price point. Well done Madisound!

Yeah, the price is almost to good to pass up. Very tempted myself to pick up a pair and do a build this winter when I have a bit more time. This hobby just keeps sucking me in.