Vikash said:
The simulator needs to know the acoustic centres so to sum the curves realistically. For 2.5 kHz the emanating point of the midbasses is about 3/5 their cone depth (from inside to outside) and the tweeter's point lies on the baffle plain. You have to feed the simulator with -z (midbasses emanating depth) -Y (bottom midbass vertical position) +Y (top midbass vertical position) plus x axis distances relatively to the tweeter's position which must be taken as the reference and all measurements taken at that point. Use 2m distance so the measurements will be surely farfield. If all caution is taken, your sim will sum the way you measure. As for the mic I still think that it gains a bit in the highs because tweeters normally show something in between 0 & -30 deg datasheet curve in the farfield. But it maybe +1 to + 2dB and of no consequence since its only the last octave. Plus some cards and cabling need a bit of a push there and maybe you are even.
As for MTM, yes its not that good. Many problems with power response, and if you don't have 90deg phase difference at cross (and nothing else), there is no D'Appolito lobe goodness anyway.
Its just that it looks nice, doubles cone surface in tall and narrow trendy cabs and boosts the sensitivity. But we know better in DIY, dont we?
No it's not connected in parallel with the source. That's why the sim looks better than the measured. The last set of measurements are with L2 connected properly and which is the tweeter response is higher than initally predicted.mhennessy said:
Hi Vikash,
Is L2 really connected in parallel with the source, not the tweeter? This could well be "confusing" the sim s/w...
I wonder if a 2.5way design is the next step? Solves the MTM problems, and will be a serious crossover design learning-experience
Mark
Well spotted.
The null at 2.5k has now gone just by attaching the rear connector plate. Weird. I was doing all my previous measurements with the parts hanging out the back (apart from LF measurements of course) and it just didn't occur to me to try it sealed up. I still don't understand why, but it's solved without worrying about time-alignment nonetheless.
It seems all TDL had to do was add an L-Pad and the tizzy top which was the biggest problem with the RTL3's would have been a smaller problem! 30 degrees off axis this (very cheap) tweeter has a very good FR. I'm not up to measuring distortion yet (and not sure I'd want to on these drivers
)
Without further ado, here's the final result. Now for the other speaker and I think I'll be ahead of your forecasted finishing time PM
It seems all TDL had to do was add an L-Pad and the tizzy top which was the biggest problem with the RTL3's would have been a smaller problem! 30 degrees off axis this (very cheap) tweeter has a very good FR. I'm not up to measuring distortion yet (and not sure I'd want to on these drivers
)Without further ado, here's the final result. Now for the other speaker and I think I'll be ahead of your forecasted finishing time PM
Attachments
Hi Vikash.
I have a pair of RTL2's which Ive modded so I thought you might like to see what I've done to them. Maybe you have some tips for me also?
Thanks,
Mike.
RTL2 Modding
I have a pair of RTL2's which Ive modded so I thought you might like to see what I've done to them. Maybe you have some tips for me also?
Thanks,
Mike.
RTL2 Modding
Hi All
I am new here and was drawn to the forum when i was searching for mods for the RTL3.
Yes bass is great from this budget speaker, but the highs could be tamed.
Mine are 17 yrs old.
Vikash what tweeter did u settle on. Vifa?
And yr X over mods entailed better components and just the L pad pots?
Thanks
Shahrin
I am new here and was drawn to the forum when i was searching for mods for the RTL3.
Yes bass is great from this budget speaker, but the highs could be tamed.
Mine are 17 yrs old.
Vikash what tweeter did u settle on. Vifa?
And yr X over mods entailed better components and just the L pad pots?
Thanks
Shahrin
Greetings all
For anyone who is interested due to a failed bass driver i reworked the speakers completely and this thread was one of the references used so only right and just i post my results back.
Orignal mid/bass units were apparently based on SPH 175's with some changes requested by TDL. As i wanted to "upgrade" i built a config around the SPH176, similar but more powerful unit it received good reviews from a german reference and was used in a setup herre which helped point me in the right direction: http://www.humblehomemadehifi.com/download/Humble%20Homemade%20Hifi_LBS_copy.pdf
The tweeter was replaced with Morel Cat378, mainly because its the same size, is reasonable priced and its sensitivity matched the twin 176's so the crossover was easier.
The original crossover components were all v cheap and having replaced a burnt crossover not long after purchase i noticed when refurbing that despite being an RTL3 part the cossovers weren't identical! I could only win from there...
I plotted FR and impendance curves from the drivers and used the Bagby spreadsheet to get an understanding of what results different component values gave.
After some listening and tweaking I ultimately built a first order crossover using poly caps and air inductors with zobel for the woofers.
Its fair to say the speakers are far from what they were - very enjoybale, shame i would need to buy a stadium to let them really sing. This was some time ago now but happy to dig out the specifics and photos if anyone's interested.
For anyone who is interested due to a failed bass driver i reworked the speakers completely and this thread was one of the references used so only right and just i post my results back
.Orignal mid/bass units were apparently based on SPH 175's with some changes requested by TDL. As i wanted to "upgrade" i built a config around the SPH176, similar but more powerful unit it received good reviews from a german reference and was used in a setup herre which helped point me in the right direction: http://www.humblehomemadehifi.com/download/Humble%20Homemade%20Hifi_LBS_copy.pdf
The tweeter was replaced with Morel Cat378, mainly because its the same size, is reasonable priced and its sensitivity matched the twin 176's so the crossover was easier.
The original crossover components were all v cheap and having replaced a burnt crossover not long after purchase i noticed when refurbing that despite being an RTL3 part the cossovers weren't identical! I could only win from there...
I plotted FR and impendance curves from the drivers and used the Bagby spreadsheet to get an understanding of what results different component values gave.
After some listening and tweaking I ultimately built a first order crossover using poly caps and air inductors with zobel for the woofers.
Its fair to say the speakers are far from what they were - very enjoybale, shame i would need to buy a stadium to let them really sing
. This was some time ago now but happy to dig out the specifics and photos if anyone's interested.Making RTL4's sound like Studio 1's
Hi guys, I just bought some RTL4's on Ebay to replace my Studio 1's as you cant get parts for them any more, but I am really disappointed with them... I find the trebble literally shocking, like I am listening to a track I love and suddenly some harsh thing happens and shocks me out of my mood. And also most surprisingly since they are like twice the size of the Studio 1's, I find they are lacking in bass, I mean the room shakes and everything but they sound really 'thin'... The studio 1's could literally make the air thick with bass, even if they could only go half as loud... And generally I just feel the Studio 1's made music and these make noise.
So I was just wondering if any one here had any tips on things I can do to make the RTL4's sound like the Studio 1s but just go louder!
I know this thread isn't about RTL4's but its the closest I could find!
Hi guys, I just bought some RTL4's on Ebay to replace my Studio 1's as you cant get parts for them any more, but I am really disappointed with them... I find the trebble literally shocking, like I am listening to a track I love and suddenly some harsh thing happens and shocks me out of my mood. And also most surprisingly since they are like twice the size of the Studio 1's, I find they are lacking in bass, I mean the room shakes and everything but they sound really 'thin'... The studio 1's could literally make the air thick with bass, even if they could only go half as loud... And generally I just feel the Studio 1's made music and these make noise.
So I was just wondering if any one here had any tips on things I can do to make the RTL4's sound like the Studio 1s but just go louder!
I know this thread isn't about RTL4's but its the closest I could find!
TDL RTL4. 8" MTM polycone bass. We've had quite a few old speakers lately that have been wired out of phase. To test this, face the two speakers close to each other, and if the bass disappears, THAT is your problem.
Don't know about the treble issue. Maybe corroded connectors or loose screws? Have a delve. A good mechanic checks everything is in good condition. Just unclipping connectors and reclipping them gets rid of corrosion. Of course, those little blue 50V NP electrolytic capacitors in the crossovers deteriorate with age, and soldered joints can get dry and broken. Don't know how relevant this is, but old ferrofluid tweeters also deteriorate with age. The oil evaporates leaving a solid brown sludge in the magnet gap.
Not much choice but to replace them.
Don't know about the treble issue. Maybe corroded connectors or loose screws? Have a delve. A good mechanic checks everything is in good condition. Just unclipping connectors and reclipping them gets rid of corrosion. Of course, those little blue 50V NP electrolytic capacitors in the crossovers deteriorate with age, and soldered joints can get dry and broken. Don't know how relevant this is, but old ferrofluid tweeters also deteriorate with age. The oil evaporates leaving a solid brown sludge in the magnet gap.
Not much choice but to replace them.
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Oh, while I think of it. There is another common problem with old speakers. Voice-coil rubbing. The speaker sags down with time.
Put your fingers below the bass dustcaps and push them in. If you hear a sort of crunchy scraping sound, you need to fix this.
Take the bass speaker out and mark the upwards direction with an arrow with an indelible marker. Then turn it 90 degrees. Usually fixes it.
Put your fingers below the bass dustcaps and push them in. If you hear a sort of crunchy scraping sound, you need to fix this.
Take the bass speaker out and mark the upwards direction with an arrow with an indelible marker. Then turn it 90 degrees. Usually fixes it.
@system7, thanks so much for those tips! I blew my amp yesterday so I am just waiting for another one (I know, I know blowing his speakers, blowing his amp what is this guy like!) but I'll try the phase thing you mention when that arrives...
The other things though all appear to be fine, no bass crunching, no sludge on the tweeters, no corrosion I can see (though I'm not quite sure what to look for)... They seem in pretty good nick to me...
What I do notice though is that literally every detail of the Studio 1's is of a higher quality (Studio 1's NOT RTL 1's btw Studio 1's are the older models that were the bottom of their range at the time but even so they cost more than the RTL 4s did). The wood is much higher density mdf, rather than the chipboard the RTL's are made from, the entire of the inside is covered in egg box foam and behind the cones is very loose wool in addition to the white woool panels (which they do both have), the binding posts are gold plated rather than plastic, the bass cone is doped cobex rather than paper, the tweeters are magnezium etc etc...
So I suppose it shouldn't be surprising that all those things make a big difference! I am not averse to spending some money on upgrading some components and or damping the cabinet... But I'd seriously appreciate some advice on what I could do that will have the most impact... Like the cabinet damping, will that make any difference, or just make the mid bass disappear even more? (I am confused about the difference between 'Reflex Transmission Line' and 'true' transmission line, is it just all the foam and stuff?). What about replacing the tweeters with something sweeter? Or will that be a major ball ache involving doing crossover stuff (which I have NO idea about at all)? Or should I just sell them and just bite the bullet and buy something better!
The other things though all appear to be fine, no bass crunching, no sludge on the tweeters, no corrosion I can see (though I'm not quite sure what to look for)... They seem in pretty good nick to me...
What I do notice though is that literally every detail of the Studio 1's is of a higher quality (Studio 1's NOT RTL 1's btw Studio 1's are the older models that were the bottom of their range at the time but even so they cost more than the RTL 4s did). The wood is much higher density mdf, rather than the chipboard the RTL's are made from, the entire of the inside is covered in egg box foam and behind the cones is very loose wool in addition to the white woool panels (which they do both have), the binding posts are gold plated rather than plastic, the bass cone is doped cobex rather than paper, the tweeters are magnezium etc etc...
So I suppose it shouldn't be surprising that all those things make a big difference! I am not averse to spending some money on upgrading some components and or damping the cabinet... But I'd seriously appreciate some advice on what I could do that will have the most impact... Like the cabinet damping, will that make any difference, or just make the mid bass disappear even more? (I am confused about the difference between 'Reflex Transmission Line' and 'true' transmission line, is it just all the foam and stuff?). What about replacing the tweeters with something sweeter? Or will that be a major ball ache involving doing crossover stuff (which I have NO idea about at all)? Or should I just sell them and just bite the bullet and buy something better!
Was it the RTL4's that blew your amp? Might be an unpleasant low 4 ohm load with two 8 ohm 8" basses in parallel.
Regardless, these splendid old cabs are worth rebuilding, even with modern drivers and crossovers. The Studio 1 design looks good.
I'm not too hot on what basses work well in transmission lines, but am the absolute whizz on crossovers and drivers in general. So you'll be alright.
Regardless, these splendid old cabs are worth rebuilding, even with modern drivers and crossovers. The Studio 1 design looks good.
I'm not too hot on what basses work well in transmission lines, but am the absolute whizz on crossovers and drivers in general. So you'll be alright.
I dont think it was the RTL's fault, I was fiddling around with the wires and I think I shorted it, or maybe it over heated...
I'd say the Studio 1's are 'splendid old cabs' but the RTL 4s not so much... Far more 'cheap and cheerful'. I can buy some replacement drivers for the Studio 1's, its just I *know* I'll blow them again as they just cannot make the volume levels I am hankering after... So I have to make a decision really (no unlimited resources unfortunately) fix the Studio 1's which I love and have had for 20+ years and try to 'grow up' and turn it down, or fix up the RTL4's and maybe fall in love with them...
Regards option two, I've heard other people comment on the harshness of the RTL 4 tweeter, so I thought I could start with that- I could afford maybe £80 for two new ones...So will that be worth doing, I mean I am pretty sure the current ones are working just how they are supposed to, I just don't like them, so if it was worth changing them, what should I go for do you think? Smoothness and beauty are more important to me than attack and punch (I like the shock and awe to come from volume and the fact stuff is falling off the shelves...) Or for that kind of money would I only end up replacing them with things that are probably no better?
And whats your thoughts on the internal cabinet damping idea?
I'd say the Studio 1's are 'splendid old cabs' but the RTL 4s not so much... Far more 'cheap and cheerful'. I can buy some replacement drivers for the Studio 1's, its just I *know* I'll blow them again as they just cannot make the volume levels I am hankering after... So I have to make a decision really (no unlimited resources unfortunately) fix the Studio 1's which I love and have had for 20+ years and try to 'grow up' and turn it down, or fix up the RTL4's and maybe fall in love with them...
Regards option two, I've heard other people comment on the harshness of the RTL 4 tweeter, so I thought I could start with that- I could afford maybe £80 for two new ones...So will that be worth doing, I mean I am pretty sure the current ones are working just how they are supposed to, I just don't like them, so if it was worth changing them, what should I go for do you think? Smoothness and beauty are more important to me than attack and punch (I like the shock and awe to come from volume and the fact stuff is falling off the shelves...) Or for that kind of money would I only end up replacing them with things that are probably no better?
And whats your thoughts on the internal cabinet damping idea?
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