next use for the L-pads
Hi Stuart,
I apologise for asking you the parts details yesterday.
Today I have found the page here with your circuit diagram,
which shows the 4ohm resistor, and there is mention of the MD500 elsewhere.
I had confused in memory your mid-domes with those of another poster in this this thread.
The way the L-pads are currently connected allows you to attenuate the entire midrange.
I can describe another way to connect the L-pad which will allow you to attenuate the upper mids with very little change to the lower mids.
BUT, you will have to set the lower mids level via a resistor first, so that lower mids are at the level you prefer -{over the average of your recordings}-
so that you can then focus your hearing on the upper mids.
Without this resistor the lower mids will be at least a little too prominent after you change the L-pad circuit location.
Thus, first measure BOTH sides of {both} L-pad/s - that is from Pin 2 to each of Pin 1 and Pin 3 for both, and post the results here.
The actual resistance required will not likely equal the 2 <---> 3 resistance, because it will be connected in a different place in the circuit
{at least till you get the upper mids decided, and perhaps permanently}.
I do need to know the 2 <---> 1 resistances to calculate the actual attenuation you have decided.
Re-connect the tweeters to reverse Polarity before you finalise the L-pads' settings, if different settings have been prefered for Polarity difference.
There is more to the Polarity aspect which I can address later if you have a preference for one over the other,
but it is better to set relative levels with the drivers connected as Celestion chose.
*************************************************************
Do you have any lower than 4 ohms resistors currently ?
If so, post resistance and power rating here.
Hi Stuart,
I apologise for asking you the parts details yesterday.
Today I have found the page here with your circuit diagram,
which shows the 4ohm resistor, and there is mention of the MD500 elsewhere.
I had confused in memory your mid-domes with those of another poster in this this thread.
The way the L-pads are currently connected allows you to attenuate the entire midrange.
I can describe another way to connect the L-pad which will allow you to attenuate the upper mids with very little change to the lower mids.
BUT, you will have to set the lower mids level via a resistor first, so that lower mids are at the level you prefer -{over the average of your recordings}-
so that you can then focus your hearing on the upper mids.
Without this resistor the lower mids will be at least a little too prominent after you change the L-pad circuit location.
Thus, first measure BOTH sides of {both} L-pad/s - that is from Pin 2 to each of Pin 1 and Pin 3 for both, and post the results here.
The actual resistance required will not likely equal the 2 <---> 3 resistance, because it will be connected in a different place in the circuit
{at least till you get the upper mids decided, and perhaps permanently}.
I do need to know the 2 <---> 1 resistances to calculate the actual attenuation you have decided.
Re-connect the tweeters to reverse Polarity before you finalise the L-pads' settings, if different settings have been prefered for Polarity difference.
There is more to the Polarity aspect which I can address later if you have a preference for one over the other,
but it is better to set relative levels with the drivers connected as Celestion chose.
*************************************************************
Do you have any lower than 4 ohms resistors currently ?
If so, post resistance and power rating here.
I'll be a few days listening yet I think. I noted a reduction in bass output after changing to the 70uF bass caps, and I'm experimenting with moving the speakers towards my back wall a little more. This certainly improves the bass, up to a point. Too close to the back wall and it starts to get a bit muddy and overblown. This back and forth movement also has an effect on the mid range, which recedes as I move the speakers back (although the upper mid is still a little hard in any location) so I'll have to experiment with my L-pads in thier present circuit placement to find my ideal.
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My L-pads are wired to attenuate the whole mid-range at present. I find that moving the speakers closer to my back wall improves the bass somewhat, but causes the mid to recede. I don't know if this is a peculiarity of my room and I expect it's also a bad idea to be changing too many parameters at once. I'm experimenting with the L-pad settings to try to restore the overall mid-range balance. Even so, I still find the upper mids prominent, so once I've found a setting that sounds best overall, I'll post the L-pads resistances and hopefully Alan will be kind enough to recommend a fixed resistor value to replace the L-pads. I'll then use them to experiment with attenuating the upper mids, if Alan can tell me how to wire them. Before I do that, I'll also swap my tweeters back to the original polarity.
I'm working in the dark when it comes to sound too.
Any information from Alan as to how to further improve the low bass would also be gratefully received!
By the way Alan, your time and effort is much appreciated.
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Stuart,
find a room position for the speakers where the lower mids sound good,
and where the bass is acceptable or can be lived with.
I'll explain more about the change in bass sound as result of change of capacitor type when I have sufficient time available.
The midrange sound is what determines the accuracy of the loudspeaker,
and as you change the horizontal listening distance you are also at least slightly changing the vertical listening axis.
The lower mids are coming from BOTH the woofer and the MD500,
thus one needs to have a vertical listening axis at which those two signals add coherently.
Optimum vertical listening axis for upper-mids' MD500 to tweeter can be adjusted via suitable resistance, or one capacitor change if necessary, later,
but do listen now with the tweeter Polarity connected as Celestion had it ...
I'll explain more about that later also ... including why your listening experience may be different from damaltor's in that matter.
For now, get the lower mids as close as you can to what you want to hear from that portion of the audio spectrum.
find a room position for the speakers where the lower mids sound good,
and where the bass is acceptable or can be lived with.
I'll explain more about the change in bass sound as result of change of capacitor type when I have sufficient time available.
The midrange sound is what determines the accuracy of the loudspeaker,
and as you change the horizontal listening distance you are also at least slightly changing the vertical listening axis.
The lower mids are coming from BOTH the woofer and the MD500,
thus one needs to have a vertical listening axis at which those two signals add coherently.
Optimum vertical listening axis for upper-mids' MD500 to tweeter can be adjusted via suitable resistance, or one capacitor change if necessary, later,
but do listen now with the tweeter Polarity connected as Celestion had it ...
I'll explain more about that later also ... including why your listening experience may be different from damaltor's in that matter.
For now, get the lower mids as close as you can to what you want to hear from that portion of the audio spectrum.
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Hi Alan - I've reconnected my tweeters as originally wired (out of phase with the other drivers) and moved the speakers forward again to thier original position. Both L-pads, disconnected, measure:
1-2 40 ohm
1-3 40 ohm
2-3 1 ohm
This, to my ear, gives the best overall balance and is back to my original preference.
Now for the fickle bit - Since changing the bass caps, and having swapped the tweeters back to the original polarity, I now prefer the tweeters this way! Ignoring the reticence in the deepest bass notes meantime, the sound is lively, out of the box and the upper mid prominence seems somewhat reduced although still noticable on some recordings. To put it in perspective though, I am talking in absolute terms, so I think I'm being a bit picky in the 'fine tuning'.
I had a look in my box of bits, and all I have is 3 3R9 resistors...
1-2 40 ohm
1-3 40 ohm
2-3 1 ohm
This, to my ear, gives the best overall balance and is back to my original preference.
Now for the fickle bit - Since changing the bass caps, and having swapped the tweeters back to the original polarity, I now prefer the tweeters this way! Ignoring the reticence in the deepest bass notes meantime, the sound is lively, out of the box and the upper mid prominence seems somewhat reduced although still noticable on some recordings. To put it in perspective though, I am talking in absolute terms, so I think I'm being a bit picky in the 'fine tuning'.
I had a look in my box of bits, and all I have is 3 3R9 resistors...
sound and capacitor dielectric type
Hi Stuart ... and to everyone who is following this Sound issue.
I have added the {_____}s with the capacitor types to the text in the Quote Box above.
The primary reason for everything you have heard, as you describe above, is the very low dielectric absorption of the polypropylene capacitors.
There is very little signal being longer stored and delayed in release with these caps in circuit.
With the bipolar electro caps a significant portion of the signal is stored longer in the dielectric and later released.
Delayed signal release causes a smearing of the sound, and in this case with most of it being below 500 Hz is heard as a thickening of the lower mids & upper bass, less precision of dynamics' changes, and an emphasis of the lower bass - all because of the sustained release of the signal.
OK, you like the added weight to the lower bass, but it is a colouration caused by the electro caps - it is not what is coming from the amplifier to the loudspeakers !
You get a choice - you have heard 2 options.
A 3rd option :-
you could use the 80uF electro caps in either of the C6, or C8, positions with the 70uF poly caps in the other position.
This will give an approximately half-way sound between the extremes you have heard,
BUT, neither C6 nor C8 option will give a simple Half-Quantity effect, because each cap is in a different electrical part of the circuit
- the inductor in between them causes each cap's colouration effect to be different.
Also, the absorbed/sustained release signal from the cap closest to the woofer arrives at the woofer before the absorbed/sustained released from the other cap does.
Next is some overlap when delayed signal from both caps is reproduced from the woofer,
and finally is the last audible contribution from the pre-inductor cap.
As result of the those Time Delays, which are very short and thus cause different phase differences for all the frequencies within the filter's bandwidth, a different addition + subtraction effect of specific frequencies in that bandwidth is caused by each of C6 to woofer and C8 to woofer.
You may like the sound of one option better than the other, or you may not like either.
Each will cause a different type of sound from the lower mids and upper bass, though either MAY cause ALMOST the same type sound from the lower bass, albeit to lower magnitude than when both caps are electros.
However, neither is Accurate - both are Colouration - you decide what you prefer to hear.
You will have to experiment and listen,
BUT FIRST, let's get the upper-mids attenuation close to optimum, then you will have a Reference to compare the lower bands' sounds to.
Remember, you earlier described changing the acoustics of your listening room to absorb a bit more of the midrange.
It is possible you may have added a little too much dampening material, or absorptive structure, and have thus absorbed a little of the lower bass also, even though that will be less absorbed than the mids.
If you have the acoustics of your room close to how you want, then we can proceed to attenuating the upper mids,
BUT, if you may have to change anything in the room later which may affect the entire midrange sound, then do that now,
then listen and re-adjust the L-pads if necessary, and Post the re-set ohms for each terminal <---> terminal position.
If I'm remembering correctly you bought Welwyn WP4S series resistors from Farnell... ?
These will be suitable for the attenuating resistor for the lower mids,
but please do confirm here what you can easily buy, as there may be a slightly closer to optimum resistance available from another brand.
{There is no closer to optimum available in the Caddock resistors which Farnell stock.}
Given the different electrical position in the circuit for the attenuating resistors than where the L-pads are the resistance will have to be a little larger than the 1 ohm you have measured.
For the easily available resistances in the UK in suitable power rating,
choice is 1.2 ohm if you are happy with the acoustics of your room as is,
or 1.5 ohm if you think you may have to reduce the LOWER-mids a little more.
Later, after repositioning L-pads to determine upper mids attenuation and putting a resistor there, I will describe a 3rd connection option for the L-pads which will allow you to fine-tune the portion of the low-mids band from the MD500 that is at the 500 Hz crossover point.
It is unfortunate that you have only 3 of 3.9 ohm.
If you had 6 pieces, you could connect for a pair of parallel triplets:-
3.9//3.9//3.9 = 1.3, close enough to try for the mids' attenuation.
Given the low price of Welwyn WP4S in relation to Postage cost, you could buy two of both 1.2 ohm and 1.5 ohm now if you are not sure what you may have to do later,
however, you will likely be buying at least one more pair of resistors after the next L-pad experiment, and perhaps another pair after the 3rd L-pad experiment if you decide to not leave the L-pads permanently in the 3rd position.
If you have the 0.5 ohm in the tweeter circuit currently, then leave it there whilst the upper mids is being decided,
unless you know the high treble region is slightly too reticent for your final preference ... though it will be simpler to decide tweeter level after upper-mids, because you may have to change one capacitor in the tweeter circuit OR try another trick with your then surplus 4 ohm resistor with your 0.68uF cap {previously removed}.
I've posted enough for now.
Proceed, or post a reply, and I'll describe the circuit connection for the L-pad as soon as I have time available.
Hi Stuart ... and to everyone who is following this Sound issue.
I have added the {_____}s with the capacitor types to the text in the Quote Box above.
The primary reason for everything you have heard, as you describe above, is the very low dielectric absorption of the polypropylene capacitors.
There is very little signal being longer stored and delayed in release with these caps in circuit.
With the bipolar electro caps a significant portion of the signal is stored longer in the dielectric and later released.
Delayed signal release causes a smearing of the sound, and in this case with most of it being below 500 Hz is heard as a thickening of the lower mids & upper bass, less precision of dynamics' changes, and an emphasis of the lower bass - all because of the sustained release of the signal.
OK, you like the added weight to the lower bass, but it is a colouration caused by the electro caps - it is not what is coming from the amplifier to the loudspeakers !
You get a choice - you have heard 2 options.
A 3rd option :-
you could use the 80uF electro caps in either of the C6, or C8, positions with the 70uF poly caps in the other position.
This will give an approximately half-way sound between the extremes you have heard,
BUT, neither C6 nor C8 option will give a simple Half-Quantity effect, because each cap is in a different electrical part of the circuit
- the inductor in between them causes each cap's colouration effect to be different.
Also, the absorbed/sustained release signal from the cap closest to the woofer arrives at the woofer before the absorbed/sustained released from the other cap does.
Next is some overlap when delayed signal from both caps is reproduced from the woofer,
and finally is the last audible contribution from the pre-inductor cap.
As result of the those Time Delays, which are very short and thus cause different phase differences for all the frequencies within the filter's bandwidth, a different addition + subtraction effect of specific frequencies in that bandwidth is caused by each of C6 to woofer and C8 to woofer.
You may like the sound of one option better than the other, or you may not like either.
Each will cause a different type of sound from the lower mids and upper bass, though either MAY cause ALMOST the same type sound from the lower bass, albeit to lower magnitude than when both caps are electros.
However, neither is Accurate - both are Colouration - you decide what you prefer to hear.
You will have to experiment and listen,
BUT FIRST, let's get the upper-mids attenuation close to optimum, then you will have a Reference to compare the lower bands' sounds to.
Remember, you earlier described changing the acoustics of your listening room to absorb a bit more of the midrange.
It is possible you may have added a little too much dampening material, or absorptive structure, and have thus absorbed a little of the lower bass also, even though that will be less absorbed than the mids.
If you have the acoustics of your room close to how you want, then we can proceed to attenuating the upper mids,
BUT, if you may have to change anything in the room later which may affect the entire midrange sound, then do that now,
then listen and re-adjust the L-pads if necessary, and Post the re-set ohms for each terminal <---> terminal position.
If I'm remembering correctly you bought Welwyn WP4S series resistors from Farnell... ?
These will be suitable for the attenuating resistor for the lower mids,
but please do confirm here what you can easily buy, as there may be a slightly closer to optimum resistance available from another brand.
{There is no closer to optimum available in the Caddock resistors which Farnell stock.}
Given the different electrical position in the circuit for the attenuating resistors than where the L-pads are the resistance will have to be a little larger than the 1 ohm you have measured.
For the easily available resistances in the UK in suitable power rating,
choice is 1.2 ohm if you are happy with the acoustics of your room as is,
or 1.5 ohm if you think you may have to reduce the LOWER-mids a little more.
Later, after repositioning L-pads to determine upper mids attenuation and putting a resistor there, I will describe a 3rd connection option for the L-pads which will allow you to fine-tune the portion of the low-mids band from the MD500 that is at the 500 Hz crossover point.
It is unfortunate that you have only 3 of 3.9 ohm.
If you had 6 pieces, you could connect for a pair of parallel triplets:-
3.9//3.9//3.9 = 1.3, close enough to try for the mids' attenuation.
Given the low price of Welwyn WP4S in relation to Postage cost, you could buy two of both 1.2 ohm and 1.5 ohm now if you are not sure what you may have to do later,
however, you will likely be buying at least one more pair of resistors after the next L-pad experiment, and perhaps another pair after the 3rd L-pad experiment if you decide to not leave the L-pads permanently in the 3rd position.
If you have the 0.5 ohm in the tweeter circuit currently, then leave it there whilst the upper mids is being decided,
unless you know the high treble region is slightly too reticent for your final preference ... though it will be simpler to decide tweeter level after upper-mids, because you may have to change one capacitor in the tweeter circuit OR try another trick with your then surplus 4 ohm resistor with your 0.68uF cap {previously removed}.
I've posted enough for now.
Proceed, or post a reply, and I'll describe the circuit connection for the L-pad as soon as I have time available.
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an interim circuit
Hello again Stuart,
further to yesterday, I am presuming you disconnected at least one terminal of each L-pad from the circuit before you measured,
because you'd unlikely see 40 ohms 1 - 2 and 1 - 3 if in circuit,
but if the 2 - 3 was in circuit its actual resistance will be greater than 1 ohm.
An interim circuit:-
to decide this 1.2 or 1.5 ohm resistor matter,
the mids' attenuation resistor will have to be in circuit as if it is a part of the 25uF cap.
It can be connected in Series with either end of that cap - that is, at input to the mids' filter, or between the 25uF cap and the junction point of the 2.2mH and .34mH inductors - whichever position is easier, but use same position for both crossovers.
For interim, connect pins 2 <--> 3 of the L-pads between where the resistor will later be.
Leave pin 1 open, not connected to anything in the circuit, and with the body placed so that pin 1 can not touch any metal parts of the circuit.
Adjust the L-pads and listen.
I think it likely you will decide a resistance between 1.2 - 1.5 ohms, but if you decide larger, such as around 1.8 ohm, don't be too surprised.
With very low resistances, near 1 ohm, if you have long wires connecting the L-pads to the board, then measure to include the resistance of the wires in the final measurement.
With the L-pads in this circuit position the change in tone of the midband may be audibly slightly different for small changes of pad setting than was the case in the other position, particually in how the upper mids change.
Try to ignore the upper mids, and focus on the lower mids and decide a resistance for the lower mids.
If the sound of the upper mids is too intrusive to allow you to decide a setting for the lower mids, then with your 3 spare 3.9 ohm resistors, use 2, but ONLY if they are 2 watts or higher rated power.
Connect a 3.9 ohm resistor in electrical Parallel with the 4 ohm resistor that is in the upper mids' circuit -{the resistor in Series with the 4uF cap}.
This will not be a permanent fixture, but has to be electrically conductive, thus scrape clean a section of each end of the in-circuit 4 ohm resistor.
Scrape clean a section of each lead end of a spare 3.9 resistor and form a small Hook shape with the cleaned wire section of each end.
Hook over the cleaned sections of the 4 ohm's leads and solder there.
This parallel connection reduces the resistance to about 2 ohms, thus allows a little more filtering of the upper mids through the 4uF cap bypassing the MD500,
but is not so low in resistance to risk excess audible Parallel Resonance of the cap with the MD500's voice-coil inductance.
2 ohms may not be the ideal resistance here, but I think now that it will be closer to optimum than 3.9 ohms there.
After you have decided the resistance with the L-pads at the input to the mids' filter, this 4 ohm // 3.9 ohm resistors' network will be removed and the pins 2 <--> 3 of the L-pads will be connected in their place.
Try this if you want to, and post the resistances you decide you prefer for 2 - 3 in Series with the 25uF cap.
In the final installation you can have the attenuating resistors in the circuit position that you prefer the sound of, but whilst you are deciding the upper mids' level next you will need a resistor to be in series with the 25uF cap, because it is too difficult audibly to get a precise setting for a low resistance in the upper mids' circuit when there are other resistors in close electrical connection to that part of the circuit.
If your audibly preferred setting is exactly half-way between 1.2 and 1.5, or same between 1.5 and 1.8,
then post the resistance and we'll deal with that then, if ...
Hello again Stuart,
further to yesterday, I am presuming you disconnected at least one terminal of each L-pad from the circuit before you measured,
because you'd unlikely see 40 ohms 1 - 2 and 1 - 3 if in circuit,
but if the 2 - 3 was in circuit its actual resistance will be greater than 1 ohm.
An interim circuit:-
to decide this 1.2 or 1.5 ohm resistor matter,
the mids' attenuation resistor will have to be in circuit as if it is a part of the 25uF cap.
It can be connected in Series with either end of that cap - that is, at input to the mids' filter, or between the 25uF cap and the junction point of the 2.2mH and .34mH inductors - whichever position is easier, but use same position for both crossovers.
For interim, connect pins 2 <--> 3 of the L-pads between where the resistor will later be.
Leave pin 1 open, not connected to anything in the circuit, and with the body placed so that pin 1 can not touch any metal parts of the circuit.
Adjust the L-pads and listen.
I think it likely you will decide a resistance between 1.2 - 1.5 ohms, but if you decide larger, such as around 1.8 ohm, don't be too surprised.
With very low resistances, near 1 ohm, if you have long wires connecting the L-pads to the board, then measure to include the resistance of the wires in the final measurement.
With the L-pads in this circuit position the change in tone of the midband may be audibly slightly different for small changes of pad setting than was the case in the other position, particually in how the upper mids change.
Try to ignore the upper mids, and focus on the lower mids and decide a resistance for the lower mids.
If the sound of the upper mids is too intrusive to allow you to decide a setting for the lower mids, then with your 3 spare 3.9 ohm resistors, use 2, but ONLY if they are 2 watts or higher rated power.
Connect a 3.9 ohm resistor in electrical Parallel with the 4 ohm resistor that is in the upper mids' circuit -{the resistor in Series with the 4uF cap}.
This will not be a permanent fixture, but has to be electrically conductive, thus scrape clean a section of each end of the in-circuit 4 ohm resistor.
Scrape clean a section of each lead end of a spare 3.9 resistor and form a small Hook shape with the cleaned wire section of each end.
Hook over the cleaned sections of the 4 ohm's leads and solder there.
This parallel connection reduces the resistance to about 2 ohms, thus allows a little more filtering of the upper mids through the 4uF cap bypassing the MD500,
but is not so low in resistance to risk excess audible Parallel Resonance of the cap with the MD500's voice-coil inductance.
2 ohms may not be the ideal resistance here, but I think now that it will be closer to optimum than 3.9 ohms there.
After you have decided the resistance with the L-pads at the input to the mids' filter, this 4 ohm // 3.9 ohm resistors' network will be removed and the pins 2 <--> 3 of the L-pads will be connected in their place.
Try this if you want to, and post the resistances you decide you prefer for 2 - 3 in Series with the 25uF cap.
In the final installation you can have the attenuating resistors in the circuit position that you prefer the sound of, but whilst you are deciding the upper mids' level next you will need a resistor to be in series with the 25uF cap, because it is too difficult audibly to get a precise setting for a low resistance in the upper mids' circuit when there are other resistors in close electrical connection to that part of the circuit.
If your audibly preferred setting is exactly half-way between 1.2 and 1.5, or same between 1.5 and 1.8,
then post the resistance and we'll deal with that then, if ...
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Hi Alan and everyone. I haven't been ignoring your replies(post 451 esp) to my posting, just been very busy unfortunately.
Can't respond to much at the moment other than to say cheers.
But here is a little treat for Celestion fans. I searched around several years ago for the old Celestion website and eventually I found it by using the Internet Wayback machine, a very useful archive.
Try this, you may have to click on the links at the top of the page, Ditton is where its at:
http://web.archive.org/web/20000831004615/www.celestion.com/museum/celestion.htm
I will post more IDC. regards ITTF
Can't respond to much at the moment other than to say cheers.
But here is a little treat for Celestion fans. I searched around several years ago for the old Celestion website and eventually I found it by using the Internet Wayback machine, a very useful archive.
Try this, you may have to click on the links at the top of the page, Ditton is where its at:
http://web.archive.org/web/20000831004615/www.celestion.com/museum/celestion.htm
I will post more IDC. regards ITTF
sba's tweeters
Hi ittf,
"cheers" to you also !
... and thankyou indeed for posting that Link to the old Celestion information pages.
It is slow-loading, but I think I got all of several pages I tried there.
Confirmed what I suspected, that there are 2 versions of that tweeter,
thus I think that sba has samples of both HF2000 and HF1000.
-----> hello sba,
- if you are reading, and, examine your 4 samples closely for differences.
*****************************************************
Anyway, ittf, when you have time I'm still interested to know if you can hear any significant differences between any of your 66s
- hey, you're too lucky finding all those pairs, but as you were looking whilst some of us weren't you deserve what you found !
Hi ittf,
"cheers" to you also !
... and thankyou indeed for posting that Link to the old Celestion information pages.
It is slow-loading, but I think I got all of several pages I tried there.
Confirmed what I suspected, that there are 2 versions of that tweeter,
thus I think that sba has samples of both HF2000 and HF1000.
-----> hello sba,
- if you are reading, and, examine your 4 samples closely for differences.
*****************************************************
Anyway, ittf, when you have time I'm still interested to know if you can hear any significant differences between any of your 66s
- hey, you're too lucky finding all those pairs, but as you were looking whilst some of us weren't you deserve what you found !
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Alan,
From that brochure it appears that Celestion made two different tweeters, the top-of-line HF2000 that came with the 66, 25, and UL10 systems, and the HD1000 that came with everything else.
The two models have different mounting plates. Are they acoustically the same ? I don’t know.
As for the 66’s HF2000 tweeter, the adhesive paper disk surrounding the dome has a smaller diameter on the earlier version than on the later one. That’s the only discernible difference.
I hope to make some measurements this summer
Cheers
From that brochure it appears that Celestion made two different tweeters, the top-of-line HF2000 that came with the 66, 25, and UL10 systems, and the HD1000 that came with everything else.
The two models have different mounting plates. Are they acoustically the same ? I don’t know.
As for the 66’s HF2000 tweeter, the adhesive paper disk surrounding the dome has a smaller diameter on the earlier version than on the later one. That’s the only discernible difference.
I hope to make some measurements this summer
Cheers
Alan, It looks like the woofers are used up to 2 khz on the Ditton 25 system.
Hi,
(First post, but I've been following the thread with interest.)
There appear to be errors on that archived page. I've owned two pairs of 44 monitors (early 'black baffle', replaced with my current 'veneered baffle' pair); the tweeter isn't an HF1000...
This Ad. for the Ditton 44 Monitor states it's an HF2000, as does this advert for the Ditton range
Also, the archived Celestion site has the HF2000 as a 1" dome driver. It's 20mm (I've measured a dead one after the grille fell off.)
So IMO you can't really take an archived page from Celestion's own website as definitive...
Regards, Kat
(First post, but I've been following the thread with interest.)
There appear to be errors on that archived page. I've owned two pairs of 44 monitors (early 'black baffle', replaced with my current 'veneered baffle' pair); the tweeter isn't an HF1000...
This Ad. for the Ditton 44 Monitor states it's an HF2000, as does this advert for the Ditton range
Also, the archived Celestion site has the HF2000 as a 1" dome driver. It's 20mm (I've measured a dead one after the grille fell off.)
So IMO you can't really take an archived page from Celestion's own website as definitive...
Regards, Kat
Well I have never noticed the mistake re the 44 tweeter until it was pointed out here!
I have had a few pairs of 44's and 15's as well and the 25, 44 and 66 tweeters and woofers are interchangeable.
Over the years I have noticed the different quality of the 44 and 66 tweeters. (Never had any 25's so don't know about them but I guess they will be the same.) I imagine the tweeters for all 3 were all made to the same sonic specification but over the years some had more love and money spent on them by Celestion!
The best ones I ever saw had a shiney metallic red Celestion sticker on the back and a metal band on the front, compared to the ones with no sticker and lots of cardboard and no band/ridge. I am describing from memory so may be a little out. sba called it an adhesive paper disk but I think it is more cardboard-like.
As I say I always assumed the HF2000 on all 3 speakers and across the years of manufacture and in the Gale and B&O were always made to the same sonic specification but I may be wrong.
I have had a few pairs of 44's and 15's as well and the 25, 44 and 66 tweeters and woofers are interchangeable.
Over the years I have noticed the different quality of the 44 and 66 tweeters. (Never had any 25's so don't know about them but I guess they will be the same.) I imagine the tweeters for all 3 were all made to the same sonic specification but over the years some had more love and money spent on them by Celestion!
The best ones I ever saw had a shiney metallic red Celestion sticker on the back and a metal band on the front, compared to the ones with no sticker and lots of cardboard and no band/ridge. I am describing from memory so may be a little out. sba called it an adhesive paper disk but I think it is more cardboard-like.
As I say I always assumed the HF2000 on all 3 speakers and across the years of manufacture and in the Gale and B&O were always made to the same sonic specification but I may be wrong.
Yes, cardboard like. The early version Hf2000 has a 2-¼” diameter cardboard disk that just barely holds the diaphragm in place. With age these tend to lift around the edge. The late version has a 3-1/8” diameter disk that seems more secure.
I traded away two of my Hf2000s from one of my 66 systems…so now I’m left with just two Hf2000s, one early and one late version. For replacement, I’m using JBL Le26 tweeters (vintage 1970s paper-cone tweeters). I have several pairs of these and they’re one of my favorite tweeters. They’re also four ohms, but are not exactly “drop-in” replacements, since the openings must be widened a bit. So far, they sound great in the 66s, and seem to work seamlessly with the existing crossover. I’ll know more when I make some measurements.
There really seems to be a lot more replacement options for the tweeter than for the dome midrange.
I traded away two of my Hf2000s from one of my 66 systems…so now I’m left with just two Hf2000s, one early and one late version. For replacement, I’m using JBL Le26 tweeters (vintage 1970s paper-cone tweeters). I have several pairs of these and they’re one of my favorite tweeters. They’re also four ohms, but are not exactly “drop-in” replacements, since the openings must be widened a bit. So far, they sound great in the 66s, and seem to work seamlessly with the existing crossover. I’ll know more when I make some measurements.
There really seems to be a lot more replacement options for the tweeter than for the dome midrange.
LOL ! This just came to my attention. Well, I have two pairs of 66s, one original and one experimental.
ittf, I wouldn't put any serious power through your 66s until you've replaced the capacitors, which, in all likelihood, are the original 35 yr old electrolytics, now way out of spec and not properly protecting the midrange and tweeter.
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