TDL Studio 3 crossover upgrade is better and yet worse as well

Good morning. I'm picking up this thread from quite a while ago! Hope you are all well.
I have a couple of questions.

I have just replaced the metal dome tdl tweeter with this soft dome.

AUDAX TW025A0 8 ohm 12 x 8 Tweeter, replaces IMF, Celef, Radford

I like the difference so far but I've had to put quite a big resistor after the cap that's feeding it.

Original value for the metal dome was 2.2. The new one is 10 ohm. It feels like it is at the right db now and was very overbearing with lesser values.

Onto my question!

Should I adjust any other xover components now that I have added such a change in resistance (in series)?

And will such a difference to the original value put a strain on the amp/ resistor/ anything else? (I have a fairly powerful amp. 2 rotel rb981s run as monoblocks -360 w per channel)

(System 7...I bought all of the components for the crossover redesign you kindly did. Haven't put them in yet...will I need to change any of their values now I have this new tweeter? I suspect so. Probably should have tried it before the new tweeter went in!! At least I still have the old ones and now have more options to tinker with!!)

Thanks
I quote that since we are turning the page.

The speaker is something like this:

596037d1485913957-tdl-studio-3-crossover-upgrade-worse-tdl-studio-3-jpg


And the original crossover looks like this, we think, and it'll be positive polarity:

601069d1487867020-tdl-studio-3-crossover-upgrade-worse-studio-3-schematic-jpg


I don't know what possessed you to change the metal tweeters to these? I wouldn't have.
AUDAX TW025A0 8 ohm 12 x 8 Tweeter, replaces IMF, Celef, Radford

There is a thing in simple first order capacitor filters called the RC constant. What it says is you sum all series resistance (including 6 ohms for the tweeter, we guess, so we are at 8.2R for the original) and note the 3.9uF capacitance. The product gives the response.

To get the same response with a different tweeter, with now 10R plus 6R =16R, we must take the capacitor down by about half. So know we want about 2.2uF capacitor. These values are hardly critical.

TBH, this speaker seems to have a terrible "Mickey Mouse" filter. I'm honestly surprised you like it.

I would be doing something more like this, which is not exactly what you have, but shows some general ideas which I will flesh out if you are interested.:

642372d1509064609-suppose-shallow-vs-steep-argument-s7-notch-filtered-6khz-8-plus-1-png


In my experience, people often pick up these sort of polycone bass speakers sensing a bargain, because they are well-constructed. And the MTM setup is likeable for presence. And transmission line is an expensive and useful idea. But First order tweeter filters are woeful, IMO. Whyever did TDL skimp on this?

Which is why they quickly sell them again. :eek:
 
Don't know if this will help, but I have a pair of TDL Super compact speakers and I think they use the same, or very similar drivers, but in a 2way bookshelf config. Here's the crossover which I traced from them. Accounting for the sensitivity difference of a single vs twin woofer the tweeter section is quite close to your proposed crossover. Sorry but the inductors weren't marked with values.
 

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nerdorama, that's a useful post. :)

AFAIK, these are 16 ohm polycones, so my sim won't be exact on the bass. Mine optimised into a low bafflestep BW3 around 3kHz, negative polarity:

642339d1509050153-suppose-shallow-vs-steep-argument-s7-third-bw3-theoretical-png


Impedance correction must be right for the drivers, so 7.5R plus 39uF won't be right. Wonderful flat impedance! I'd guess your tweeter filter has a 0.4mH coil with 4.7R. :cool:
 

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Always grateful for people's responses. Thank you. I'm looking forward to trying out your suggestions.

I got the soft dome tweeters to see how different They d sound to the metal dome standards.

Intruiged to know why you think I shouldn't have bothered? Always good to hear the opinion of people who are better informed, technically, then me.

My main aim is to squeeze a bit more midrange out of these speakers. I appreciate that it's slightly counter to what they naturally offer but I feel like the have a more balanced sound within...
 
Hi IrishIranian, Steve and fellow posters
I have a pair of these for my main listening and have owned them for about 12 years. I wouldn't dream of replacing them unless I had to.
I found this post quite interesting as I have recently had an issue with one of the woofers (voice coil rubbing) and sought to replace it - haha, yeh good luck with that I hear you say. I attempted a repair on the woofer but unfortunately due to my inexperience, have compromised the movement of the spider - it works now without rubbing but I think its output is slighly lower than it should be. I found there aren't to many options for 16 Ohm drivers on the market but found some dual coil drivers that can be configured to 4,8 or 16 Ohms but not sure of their impact on the sound as yet.
I will also be looking at replacing the caps in the crossover (so thanks for the info on this) and in particular, the tweeter cap.
IrishIranian - If you decide to ditch any of the woofers or tweeters permenantly - PM me ..I'm sure we can come to some agreement :)
Cheers
 
For information - Studio 3 mk2 owners will find the crossover unit directly behind the binding posts on the rear of the speaker and not behind the lower bass/mid driver as shown in images on the net - which I guess are from version 1?
You will find 4 caps on the crossover - 2x 5uF caps, a 4uF cap and a 12uF cap. Please correct me if I am wrong or if you find Mk1's or MkIII's have a different setup.
 
Please help. I'm trying to understand the concept of crossovers (I finally get the concept of high and low filters and even the point of (zobel?) bypass to aid the rolloff). As you can see from my posts above, I have dived in probably before I should have - thus proving a little knowledge can be a dangerous thing.
tdl_electronics_studio_2_3-min-min.jpg I believe C1 is 12uF, C2 & C3 are 5uF and C4 is 4uF. From info on the Studio 3's manual, the crossover point should be around 3KHz ...but from what I have learnt so far, a 5uF cap in series with a 4uF cap is going to result in a much higher crossover point. Could anyone please explain what I'm missing?
Just to add, I have changed all the old ALCAP's to Polyprop's (similar values) and having carried on reading, I understand that I'm going to need to add some resistors to redress the change in ESR. At the moment the Studio 3's sound like there is a slight hole somewhere between upper mids/lower treble.
 
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Correction

TDL_studio_3_values_small.jpg
Please for forgive my second error - I have assumed the original diagrams from IrishIranian were near correct and a simplified version of my Studio 3's. Please see the diagram above where I have written in (albeit a bit scruffy, sorry) the values of the components as I traced the circuitboard on my Studio 3 mkII's.

Please ignore my message about capacitance for the tweeter in the previous post as I can now see it has 4uF and 12uF series capacitors inline with the tweeter.

I don't totally understand why there is a 5uF across the woofers and a second 5uF in series with a 15 Ohms resistor across the woofers also - from what I've read on here, I would have expected cap (C1) in series with the 15 Ohm resistor to be of a slightly higher value?

Again, apologies for the previous confusion and wrongly made assumptions.
 
OMG, THetaII, you are a nightmare! :D

Rubbing voicecoils on old 8" basses is most easily cured by rotating the driver 90 degress. Simple as that.
648700d1512068284t-tdl-studio-3-crossover-upgrade-worse-tdl_electronics_studio_2_3-min-min-jpg


That is a BW3, aka Butterworth 3rd order, it should do this with negative polarity on 8" bass:

642756d1509246366-tdl-studio-3-crossover-upgrade-worse-tdl-super-compact-fr-jpg


642755d1509246366-tdl-studio-3-crossover-upgrade-worse-tdl-super-compact-circuit-jpg


I would never take a crossover apart without drawing the schematic and what values I can read, and noting what goes where. As it goes I have an inductance and capacitance measuring multimeter that makes this all a bit easier.

It's no good pulling stuff off the internet if you don't even know it's right for your model. Manufacturers frequently vary designs.

Doubling the drivers isn't such a big deal, but will modify the crossover substantially. You need to draw the schematic of what you have with as many values as you can read. Usually start with the live and earth tracks and the driver wiring. A photo would help, because I can guess a coil from looking at it to reasonable accuracy.
 
Hehe, Yes, you are right Steve - As I said, I stupidly assumed my crossover would be the same as IrishIranian's... but I'm learning, and now get the general gist of what is going on with this crossover. Although I'm not totally sure on how to correct the esr difference - I'm thinking of adding 1 Ohm next to C1 and a 2 Ohm resistor next to 12uF cap (C4) ...does that sound along the right lines to you Steve? ..and thanks for the tip on rubbing voice coils :)
IMG_20171130_223136.jpg IMG_20171130_215441.jpg Inkedtdl_electronics_studio_3_values.jpg
 
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Hold your fire on resistor changes. Some of them will make no difference at all. Some of those MKP caps are enormous, aren't they? People seem to forget this.

Are we sure about the schematic now? I usually flip the circuit board view to get the idea.

But I feel a headache coming on, or at least bedtime. May sim this when I have time. I'd guess the two 16 ohm woofers behave like one giant 8 ohm one electrically.

But does it sound OK, or worse, or better. In what way?
 

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Thanks for your input Steve. I am fairly sure of the schematic ...now. There is more detail, but also as you and others have mentioned, changing to polyproylene caps has made the treble too loud, plus there appears to be a shortage of upper mids. Sleep well ..and any advice you can come up with is appreciated.
 
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All I see needing doing here is taking the tweeter down a bit. Looks like a (red) 15R shunt will give you -3dB, a 22R shunt -2dB. -3db being half power. A 3W wirewound or ceramic will do fine wired between the tweeter output and earth. You might drill the circuit board with a fine drill at some convenient point to fit it in where there is room. Or use a bradawl if you have one. Don't make the holes too big though, that gets hard to solder.

No changes to the bass circuit required. The red 15R and 15uF is just a modelling device I used to correct the impedance for lower inductance woofers.

All works very well in fact. A very nice design after my own heart. :)

In hindsight, regular smallish Solen MKP 250V would have been easier, no? It is nice to get a good fit. More reliable.
 

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Thanks Steve. Yes, hindsight is wonderful ;)
A lack of knowledge and a silly assumption has made this a lot harder than it needed to be - but, on the other hand, it has forced me to learn the basic concepts of high, low, 2nd and 3rd orders and Zobel ..so I have at least enjoyed the experience.
Another order in at the HiFiCollective - Cheers :)
 
Hiya,

I've just replaced all of the components in my TDL Studio 3s crossover.

I've gone for point to point soldering on the components without a pcb or board of any sort.

I've used the following components.

3.9uF 800Vdc Jantzen Superior Z-Cap (ON THE TREBLE)
10R Jantzen Superes 10W Resistor
2R2 Jantzen Superes 10W Resistor (2.2R)
12uF 450V Mundorf Mcap EVO Capacitor (ON THE BASS)

I've also got new inductors of the same value as the originals done by Gerry at Falcon who knows TDL speakers well.

The improvements in the treble is night and day. Much cleaner, more space better soundstage. The bass seems a tiny bit flabbier (not much in it though) but it's the midrange that seems to be worse. Not terrible but noticeably more muffled than before.

I've still got the original Xover in tact but before I start mixing an matching I thought I'd see what you all think could be the reason.

I'm letting them burn in/ run in to see if that makes a difference (I'm not trying to start a chat about that well trodden and controversial issue so let's pretend I never said it...just trying to eliminate all the possibilities!)

The only differences with the original values is the high pass cap which is a 3.9 rather than the original 4. I've also extended the wires a little as they were quite short and needed extra room to work. No more than 6cm with some decent van damme cable I had. I've used solder with a bit of silver in it and they have been running for a day or 2. Oh and the resistors are 10w instead of 5 but I don't believe that should make and difference.

Can anyone suggest why the midrange seems to have got worse?

Thanks

I was always a big fan of the TDL Studio 3 monitor, which was impossible to find in the US and shipping from UK is prohibitively expensive. A few years ago, I ran into some “Wharfedale M-138 Transmission Line Monitor” from Wharfedale in China (Pic 1). I bought them out of curiosity and found that they were the TDL knock-offs. They have the same aperiodic cabinet design (not TL) as the TDL (Pic 2) and a 2nd order crossover. The cabinet was very well built, but the drivers were very poor quality. I started a mod project.

wharfedale138_peerless-seas_small.jpg Wharfedale138cabinet.jpg

(1) I replaced the drivers with a pair of Peerless 850460 woofers and a Seas 22TAF/G ¾” Aluminuim/magnesium dome.

(2) I modified the cabinet by lining it with 3M 08840 Sound Deadening Pads and replaced the polyester wadding with long fiber wool.

(3) I modified the crossover to 3rd order and added a zobel network for the woofers. (Pic 3) I was able to keep the circuit board and bi-amp input panel. (Pic 4)
wharfedale138_peerless-seas_xover.JPG IMG_2391.jpg

Crossover mod was supported by Jeff Bayby’s PCD software which worked beautifully. The simulation result is shown in Pic 5. I kept the woofer bump to get a bass -6dB cut-off at 35 Hz. It worked exactly as expected. After I fine tuned the driver balance by ears, I made in-site measurement using Ivo Mateljan’s ARTA software. The dip at 450 Hz and the treble drop-off are room effect because I did not make the effort to measure outdoor. (Pic 6)
wharfedale138_peerless-seas_simulation.JPG wharfedale138_peerless-seas_measured.JPG

I have no intention of hijacking this thread. Take my post as an interesting footnote and stay on the topic of TDL. Thanks.
 
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