Replaced Audax HD100's with Audax tw025a0

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Dear people from Diyaudio,

I have struggled quite a bit before trying to solve my issue with the help form this forum. I play with a pair of wonderful mission 717's with a bit of an upgraded cross-over. After modifying my amplifier I heard an issue in my speakers. Both have a slightly different version Audax Hd100 tweeter. To solve the problem I bought the tweeter known as the "Direct replacement for...". After measuring I deal with a +/- 6dB difference. The man who sold me the tweeter kindly helped me and we measured an L-pad for the tweeter. Sadly enough just an L-pad doesn't solve my problem.

To sketch the situation at this point, the original crossover is as following:
Low pass: 1,6mH coil in series.
High pass: 6,8uF capacitor in series, 0,20mH paralel.

Simple, yet effective.
The current situation follows this + a 2,7 ohm resistor series, 5,6 ohm resistor paralel. With this impedance making it a 5,8db attenuation.

I can't honestly say that I feel like I need this or that, it's just not 'there' yet, and I'd love to get some suggestions. I made my filter external so I am able to 'play around with it'.

Hope someone can put my tweeter on the right track, I can feel it's 'almost there'....
 
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There were about five versions of the HD 100 dome tweeter and it would not surprise me if 'specials' to suit a manufacturers specification ,also exist.Do you have the exact coding for the original? i.e. HD 100 D25 SP.If you have this extra information or at least a description of the dome material it may aid in finishing the xover network.
 
Here is some info:
 

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Hey VaNarn,

I have those indeed. One of them was a plain HD100d25, the other one was a HD100d25 BA HR. The HD100d25 is more similar to the replacement tweeter. The BA HR has a smaller magnet/weight. I can tell that in the Mission 717 the woofer seems to be something like an Audax hm210 labeled as a Mission speaker designed in the UK, made in France. The tweeter was sold as a 'damped dome'.
 
Hey Sreten,

The modifications to the original crossover were replacing the nothings of caps with Audyn Cap Plus, same value. Added the Vishay bypass cap as well.

The L-pad is after the cap and coil.

almost 6dB sounds indeed as a lot, especially when this is sold as a direct replacement (thought to screw these tweeties in and be playing my tunes again..). The measurements did show that difference though. It sounds maybe a tad weird to say but it almost seems like they go so high, its inaudible, but painful to the ears.

Thanks!
 
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At face value,given normal manufacturing tolerances,an attenuator pad is not really required as the difference between the two domes in efficiency ,is one dB(on paper).There is the possibility that the original xover did not match the sensitivities of the speakers closely and relied on a deliberately contoured response to mask the problem.I would prefer to use a 3 kHz point to use the Audax TW dome with a 12 dB /octave slope network.The nearest standard values are 4.7 mFd and 0.6 mH for the capacitor and inductor ,respectively.The response of the bass/mid speaker in the upper range could be your remaining issue,as achieving a satisfactory performance around the 3kHz region is a hard ask for an 8'' unit.
 
Hello VaNarn, thanks for the help.
The person that helped me measured this with a microphone. I am not sure what's on paper. A 4,7uf cap and a 0,6mH coil does get pretty close to the speaker as I know him :), many thanks thus far.

I must say with this set-up the highs are still a tad too intensely there. A bit of a fatiguing sound. But the body is definitely back. I think it still needs a bit of attenuation through a resistor. Or would a different value coil smooth things a bit more out? Would there be another way to attenuate the tweeter a bit? When I take a bit more time listening to it, the highs are still, really really hard. though the 5,6 db L-pad sounds almost the same like I don't use the tweeter at all. Thanks, I feel like its getting closer......
 
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If the person using the microphone could do an impedance run and a frequency sweep of the system it would help solve the mismatch problem.It is not unusual to find that speakers from the nineteen seventies were balanced to sound pleasant using the sound media of that time and did not have a reasonably flat frequency response despite marketing claims.I would expect an average sensitivity of around 88dB/1w/1m for the 717 bass/mid speaker, and maybe ,a 3dB attenuator pad would be a better match.(2.2 Ohm in series;22 Ohm in parallel with the tweeter)If you are keen to experiment then I would recommend trying a Quasi second order xover using the component values given in post #7.This is a series connected network.The only other refinement would be an impedance correction network (Boucherot cell) for the 8'' speaker
 
I did some google work and came up with an RLC circuit calculator. As in this:Strassacker: Speaker Building, Components
Is that the same as a Boucherot cell? I still think there is a part in the speaker playing too loud. I re-installed the L-pad with 2,7 ohm series, 5,6 ohm paralel for a 5,8 db attenuation (this with a Zt of 5,6 ohm). I guess I have to say something different than I did in my previous post. Thats a bit confusing, it is, also for me.
Do you mean that? I do play with a tube amplifier. And I feel like somewhere in the soundstage something is really pressing, like sharp-ish. It puzzles me also that this all is caused by such a simple thing as replacing a tweeter. I guess I learned the following: replacing a tweeter isn't a simple thing.
Many thanks! I genuinely hope to get there...
 
Those were my observations too. I think how it's at some places sold as a direct replacement is an insult to the quality from the old tweeters at the time..

I've at that time discarded the tweeters and installed audio note tweeters with silver voice coils. The sounds is magnificent!

Thanks for the advice, I'll keep it in mind for friends :)!
 
Those were my observations too. I think how it's at some places sold as a direct replacement is an insult to the quality from the old tweeters at the time..

I've at that time discarded the tweeters and installed audio note tweeters with silver voice coils. The sounds is magnificent!

Thanks for the advice, I'll keep it in mind for friends :)!

I have just replaced a set of Vifa tweeters in my Dali 18mk2 with a set of Audax tw25a2, which should be a direct replacement for the Dali's original Audax hd100 tweeters.
I am not at all satisfied. The new Audax tweeters sound harsh and has to much energy in the very top of the frequency band.
What audio note tweeters have you used as a replacement? And are you still satisfied?
 
I have just replaced a set of Vifa tweeters in my Dali 18mk2 with a set of Audax tw25a2, which should be a direct replacement for the Dali's original Audax hd100 tweeters.
I am not at all satisfied. The new Audax tweeters sound harsh and has to much energy in the very top of the frequency band.
What audio note tweeters have you used as a replacement? And are you still satisfied?

I am still very satisfied, and I would not take them out to replace them with anything. Mind that they're not direct replacements, I had to correct the speaker filter to quite an extend to get it working (from 1 cap and 1 coil on the high section to 2 resistors, 2 capacitors, 2 coils). I can give you a schematic of my solution, mind that it is definitely not the cheapest solution.
Seas tweeters like the t27 perform really well or perhaps you can use 'jkojic' 's solution. Though I can't guarantee you that either solution will go well without crossover changes. Though, anything is better than the tw025.....
 
Dear people from Diyaudio,

I have struggled quite a bit before trying to solve my issue with the help form this forum. I play with a pair of wonderful mission 717's with a bit of an upgraded cross-over. After modifying my amplifier I heard an issue in my speakers. Both have a slightly different version Audax Hd100 tweeter. To solve the problem I bought the tweeter known as the "Direct replacement for...". After measuring I deal with a +/- 6dB difference. The man who sold me the tweeter kindly helped me and we measured an L-pad for the tweeter. Sadly enough just an L-pad doesn't solve my problem.

To sketch the situation at this point, the original crossover is as following:
Low pass: 1,6mH coil in series.
High pass: 6,8uF capacitor in series, 0,20mH paralel.

Simple, yet effective.
The current situation follows this + a 2,7 ohm resistor series, 5,6 ohm resistor paralel. With this impedance making it a 5,8db attenuation.

I can't honestly say that I feel like I need this or that, it's just not 'there' yet, and I'd love to get some suggestions. I made my filter external so I am able to 'play around with it'.

Hope someone can put my tweeter on the right track, I can feel it's 'almost there'....

Hallo Huub,
Bedankt voor je snelle reactie!

Heb je die oude tweeters nog?
Ik heb namelijk een herstelbedrijf gevonden in Belgie, Diksmuide.
Hij maakt zo nu en dan een rondje om kapot materiaal op te halen, oa in Eindhoven.
Ik weet niet waar je woont en opsturen is natuurlijk ook een optie.

Zelf ben ik nu aan het uitzoeken wat de oorzaak is waarom de tweeter niets doet.
De impulse heeft aparte scheidingsfilters hoog en laag.
Eerst heb ik alleen laag uitgebrobeerd, niets aan de hand.
Toen hoog, geen geluid.
Ferrovloeistof verwijderd en opnieuw geprobeerd, geen geluid.
Zou natuurlijk aan de filters kunnen liggen of aan de tweeters, het laatste ligt naar mijn idee het meest voor de hand.
Wat denk jij?
Mvg
Bart
46bart@gmail.com
 
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Hello Huub,
Thanks for your quick response!

Do you still have those old tweeters?
I have found a repair company in Belgium, Diksmuide.
Every now and then he makes a round to collect broken material, including in Eindhoven.
I don't know where you live and sending is of course also an option.

I am now trying to figure out why the tweeter is not doing anything.
The impulse has separate separation filters high and low.
At first I only tried low, nothing wrong.
When high, no sound.
Ferro liquid removed and retried, no sound.
Could of course be the filters or the tweeters, the latter is in my opinion the most obvious.
What do you think?
Best regards
Bart

English please Bart.

dave :cop:
diyAudio moderation team
 
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