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Multi-Way Conventional loudspeakers with crossovers

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Old 12th July 2010, 11:32 AM   #501
kayelem is offline kayelem  United Kingdom
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Hi Alan,
Quote:
Originally Posted by alan-1-b View Post
f you would like to Post the exact mH measured values of your inductors [...]
Ditton 44 schematic and inductor measurements posted here
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Old 12th July 2010, 02:52 PM   #502
sba is offline sba
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Here's some woofer plots (at 0, 52, and 60 degrees)--

1600 t.png

1600 tt.png

1600 ttt.png

2619 t.png

...and some THD data--

woofer comparison with THD.png

...and impedance data--

66 woofer impedance.gif


That's everything for now
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Old 13th July 2010, 01:52 PM   #503
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Default and the tweeter circuit ?

Hi sba,

its good you have been able to investigate further the nature of the measurements, and Post the additional, etc ...

I will reply with some ideas about the drivers and the crossover as soon as I have time available,
and after I have studied all your additional data Posts.


Do you have the JBL tweeters connected with no attenuation circuit ?

That is OK if you prefer the sound that way and it may suit the acoustics of your room,
but I would have thought it would be a bit too treble dominant with no attenuation ...... ?

I think you may have got rid of one of your HF2000s too soon, given the mismatch of the two remaining ...
which will be audible ! ...
... but if you prefer the JBLs perhaps HF2000s are no worry for you.


I'll Post about the mid-dome distortion later also.
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Last edited by alan-1-b; 13th July 2010 at 01:59 PM. Reason: to better space a paragraph
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Old 14th August 2010, 06:06 AM   #504
sba is offline sba
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Quote:
Originally Posted by WayneSwann View Post

I have taken the advice of Wimslow Audio and installed a pair of MOREL CAT 298 (modified with a 94mm face plate) into my Celestion Studio 66 Monitors. At the first low volume testing they sound pretty good. Their existing tweeters installed by their previous owner were a pair of rather cheapo 'Realistc' (Radio Shack) horn super tweeters. I think the problem I have found with the various bits of information placed by other members has somehow become rather obsessed with the fact that the original HF2000's were described as 'Super-tweeters' with a frequency response from 5000Hz up-to 40000Hz. As far as I understand the adult human cannot hear frequencies much above 20kHz. The MOREL's have a range of 1.8 - 20kHz. They certainly sound much better than the previous 'Realistic' tweeters which were extremely tiring to listen to for any length of time due to the edginess at the top end. I think the real star of these speakers are the mid-range drives, which are excellent in my opinion. I'm not convinced that the passive ABR is a complete success. I have also changed the binding posts, upgrading them to a pair of high quality gold plated units. I have changed the internal wiring using 'Chord Rumour Install' wire. These are 14 AWG silver plated copped stranded cables. I understand the original cables were 18 AWG silver plated copper cables. They just seemed very thin and insubstantial. Bearing in mind that when these speakers were produced amplifiers rarely exceeded output of 70 - 80 watts. Like a lot of enthusiasts I have spent a lot of time,effort and money on the speaker wires connecting the speakers to the amplifier and it just seemed sensible to use the equivalent high quality cables inside the speakers? I would now like to upgrade the crossovers. But I must admit the prospect of doing so seems to be rather a daunting task. I have found a schematic within the pages of this extremely valuable tool (DiyAudio). I have asked Wimslow Audion to provide me with the latest equivalent high quality replacement components. I understand it will be the capacitors only which will need to be replaced? I am writing this really to obtain some feedback regarding the assumptions and methodology I am adopting. I know that these questions were first raised back as early as 2004, and have been spread over many Threads. What I would like to do is to manage to amalgamate all of the knowledge regarding the upgrading these beautiful speakers in the best possible way bearing in mind that the original drivers etc are no longer available.
Wayne,
Welcome! Its better to post in this thread, because itís unlikely that those six-year old threads are being watched. Youíre on the right track though and just need to replace the capacitors, which most likely are way out of spec. Thereís info in this thread on how to do this, but at the moment I donít have time to locate the relevant posts.

****************

Alan,
Hello! Since the JBL - Le25 is about 5db more efficient than the hf2000, I installed an Lpad in the tweeter circuit. It works well and I like having the extra HF efficiency available should a particular room need it.

Iíve also had a little time to start looking at all the data that I collected, and the thing that confounds me the most are some resonances between 2 and 2.5msec on the IR plots [I havenít posted these yet.] . Theyíre apparent on all of my measurements of the LF, Mid, and HF drivers. Iím sort of curious because it makes a big difference in the FR plot whether or not these resonances are "gated" in. Once theyíre included, the FR plot becomes a lot rougher. (There are some early resonances on the IR plots that do sort of make sense, such as those that are probably caused by the cabinetís overhanging lips and grille channels, and by driver resonances. )

Itís also hard to believe that they might be room reflections, because I did my best to minimize those. The measurements were made in a large empty room with a 12Ď ceiling, with the speakers elevated, the floor dampened, and the mic placed on a suitable boom at 1.5 meters. So I really donít knowÖ If this stuff between 2 and 2.5ms has something to do with the cabinet, perhaps thereís a fix. Then again, it might also be some sort of hardware problem, perhaps with the mic preamp or something.

It will be a while before I can get setup again to do some testing, but, when I get a chance, Iíll post the detailed Impulse Response plots.
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Old 15th August 2010, 04:09 AM   #505
sba is offline sba
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Some IR plots of the Ditton 66 system measured at 0, 45, and 90 degrees--


0-8 millisec overview
Impulse 0-8 millisec.png

the same, normalized
Impulse 0-8 millisec normalized.png

this one shows what happens to the FR when the resonance at 2 millisec is gated in
Impulse 0-8 millisec (with new gating).png

0-3 millisec close-up
Impulse 0-3 millisec.png

the same, normalized
Impulse 0-3 millisec normalized.png

the same, shown with distance in cm
Impulse 0-3 millisec normalized (distance in CM).png


Any idea of what’s happening around 2 millisec / 70cm / 28 inches ?

Last edited by sba; 15th August 2010 at 04:17 AM.
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Old 15th August 2010, 09:34 PM   #506
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I have become aware of a pair of Celestion HF2001 tweeters up for sale. There have been some questions raised here on Diyaudio back in 2007 comparing them to the HF2000's. It would appear that the HF2001 was used in the 332, 442, 551 and 662 models,
whereas the HF2000 was used in the previous generation 25, 44 and 66 models. The question asked then was would the HF2001 work in an older 66? I was wondering if anyone has any more recent information regarding the HF2001's? By the way does anyone have or know of a pair of HF2000's going up for sale. I would really still like listen to them in the original Studio 66 setup, Even though I have gone down the replacement route! Using the MOREL CAT 298's as I previously described. Since my last posting I have given my Studio 66's with the MOREL replacements a longer and louder testing session. I must admit I am quite pleased with the results even though I realise the crossovers will need modification for the characteristics of the MOREL tweeters. I have asked Wimslow Audio to give me some idea of the cost involved in making the changes. I will attempt to carry out the work myself. I have a pretty steady hand with a soldering iron! I have spent quite some time looking at the equations involved in reaching the necessary values for the capacitors and other components within the crossover, but I must admit it leaves me with a degree of self doubt in my ability to come up with the correct values
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Old 16th August 2010, 02:40 AM   #507
sba is offline sba
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Quote:
Originally Posted by sba View Post
... the thing that confounds me the most are some resonances between 2 and 2.5msec on the IR plots
I narrowed the problem down to an interaction between HOLMimpulse and my sound card, an Echo Indigo I/O. Only when a soundcard calibration file is used does the caca at 2 msec appear on the IR plot. I don’t know why though… there was no problem when I tried REW (room eq wizard) using a soundcard cal.

Originally I was so focused on the FR plots that I neglected IR ones. I really wish I had magnified and examined the IRs much earlier, before making a multitude of measurements. I tried erasing the soundcard calibrations from my data files, as well as un-checking the calibration box in HOLM, but had no luck. Once the soundcard file is enabled, it seems to become an integral part of the measurements.

********************

today--

HOLM, measurement of the 66 -- caca at 2 msec still there.

.
HOLM, measurement of something different (JBL) -- caca at 2 msec still there.

.
Abandoned HOLM

.
Installed REW (room eq wizard) & made soundcard calibration.

.
REW, measurement of the 66 -- caca at 2msec not there.
http://img185.imageshack.us/img185/5976/rewb.png

.
HOLM, restarted, cleared everything, & reset default settings

.
HOLM, measurement of the 66, without soundcard calibration -- caca at 2 msec not there
http://img155.imageshack.us/img155/1361/holmwo.png

.
HOLM, made soundcard calibration
http://img710.imageshack.us/img710/3449/loop.png

.
HOLM, re-measurement of the 66, with soundcard file -- caca at 2 msec back again.
http://img294.imageshack.us/img294/1223/holmwith.png

Last edited by sba; 16th August 2010 at 02:42 AM.
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Old 16th August 2010, 04:06 AM   #508
sba is offline sba
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Quote:
Originally Posted by WayneSwann View Post
... I have spent quite some time looking at the equations involved in reaching the necessary values for the capacitors and other components within the crossover, but I must admit it leaves me with a degree of self doubt in my ability to come up with the correct values

Wayne,

Replace all of the original caps first. This will get the system closer to original spec… and protect the drivers.

If the new morel seems “bright“, then install L-pads in the tweeter circuit.

Replacement drivers should always be high quality ones that have a smooth response that needs minimal to no correction. There’s too much black magic in the 66 crossover for the home/diy user to be able to successfully alter it using various online calculators. I know this firsthand, LOL ! I put together a 12db/oct crossover for the 66 and fine-tuned it with FR measurements. It measured and sounded ok at first, but, after comparing it with the original, I had to toss it out and have a stiff drink to console me on all the hours put in. In changing the components, it’s just too easy to screw up the phase and the polar response, especially of the esteemed midrange. So if the Morel sounds good, let it ride, and enjoy the music. Moreover….you’d need acoustic measurements to see what's up with a Morel mounted in the 66.

When he returns Alan might also have some ideas on adjusting your Morel.
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Old 17th August 2010, 03:41 PM   #509
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Default Check this:

[QUOTE=sba;

Any idea of whatís happening around 2 millisec / 70cm / 28 inches ?[/QUOTE]

Hi sba,

I read in your next Post that you seem to have found the cause, or a possible cause,
for the 2 msec problem.
I do not know the idiosyncrasies of the software you are using,
however, given the distance that 2 msec corresponds to my initial suspicion is a reflection of the signal from the protruding lip at the top of the enclosure arriving at the mic.
It would be lower amplitude than the initially arriving primary signal.

If you have not suitably treated that lip with absorbent material - with one of the options I posted much earlier in this thread - then I recommend you do so and then measure again.

I apologise that I have had very little time available recently.
I hope to return and post comments and a few recommendations following your measurements soon.
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Old 17th August 2010, 04:14 PM   #510
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Default Briefly for now:

Quote:
Originally Posted by WayneSwann View Post
I have become aware of a pair of Celestion HF2001 tweeters up for sale. There have been some questions raised here on Diyaudio back in 2007 comparing them to the HF2000's. It would appear that the HF2001 was used in the 332, 442, 551 and 662 models,
whereas the HF2000 was used in the previous generation 25, 44 and 66 models. The question asked then was would the HF2001 work in an older 66? I was wondering if anyone has any more recent information regarding the HF2001's? By the way does anyone have or know of a pair of HF2000's going up for sale. I would really still like listen to them in the original Studio 66 setup, Even though I have gone down the replacement route! Using the MOREL CAT 298's as I previously described. Since my last posting I have given my Studio 66's with the MOREL replacements a longer and louder testing session. I must admit I am quite pleased with the results even though I realise the crossovers will need modification for the characteristics of the MOREL tweeters. I have asked Wimslow Audio to give me some idea of the cost involved in making the changes. I will attempt to carry out the work myself. I have a pretty steady hand with a soldering iron! I have spent quite some time looking at the equations involved in reaching the necessary values for the capacitors and other components within the crossover, but I must admit it leaves me with a degree of self doubt in my ability to come up with the correct values
Hi Wayne,

I have very little time today, thus for now:-

HF2001 is an 8 ohm spec tweeter.
It may have no better sound than HF2000, but simply different sound.

It could be adapted to work in the 66 crossover, but so can the Coles CE 4001, and that tweeter will fit the existing cut-out.

Note the unique fitting for HF2000.
I do not know if HF2001 will fit there any better than Coles CE 4001.

I'll look for data for the Morel you bought when I have time available.

Is 298 the actual Model Number of the Morel, or simply a Retailer's Catalog Number for it ?
There should be a sticker on the back of the tweeter with the Model Number printed on it.

************************************************** ****************

Changing the components to optimally match a different tweeter is not easy, as there are several things that need to be taken into account.
I strongly recommend that you go back to earlier in this Thread, and read through till you find my posts about crossovers and capacitors,
and then consider those.

Go also to the Thread titled:- Crossover nightmare!!!!!!!

started by:- lorienblack

which is about Celestion 44 which has the same crossover section for HF2000 as 66, and read through my posts there,
and fairly soon there will be more posted there about adapting the crossover to accomodate a different impedance tweeter.

I don't have time to post all that again.

Wimslow will sell you components, some of which you may not need because you may be able to use the existing inductor.
Also, I think the capacitors that Wimslow sell are not the optimum for that price.
Read in this thread the posts by dloper about the capacitor job he had done by Wimslow which did not provide him with the sound he wanted but knew could be achieved, and which we have been working on and will continue when he returns.

If you are not in a hurry then I recommend that you do not buy now what you may later regret, but spend the time reading through all the above, and whatever we post next about these 2 ongoing crossover adaptions.
Yes, there is a lot in both threads that is not relevant to your specific situation, but I do not remember exactly where everything is in both threads.
Unfortunately one has to search through things to find useful information.
It is time consuming - I do it myself, but hey ... sometimes I find other things there also which I did not know and which are useful
- that is part of diy !
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Last edited by alan-1-b; 17th August 2010 at 04:27 PM. Reason: To add a sentance
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