Resistors - wire-wound is not MOX
MOX is Metal OXide, and not metal wire.
Some listeners like the sound of metal oxide resistors, at least when those are new, but I am wary of them because the connections between the internal oxide and the metal end caps can become electrically faulty more easily than internal resistance wire does to end connections.
This is more likely to occur if the resistors get hot in use because the junction changes its electrical characteristics during the hot-cold cycle, and more-so over a long period of time of many hot-cold cycles.
Very well designed and constructed metal-oxide resistors of the oxide formulae and assembly/construction used by Caddock -{and probably also by Vishay}- will work well for very long periods because those are designed and engineered to work in critical Military, Aerospace and Medical equipment applications.
MOX is Metal OXide, and not metal wire.
Some listeners like the sound of metal oxide resistors, at least when those are new, but I am wary of them because the connections between the internal oxide and the metal end caps can become electrically faulty more easily than internal resistance wire does to end connections.
This is more likely to occur if the resistors get hot in use because the junction changes its electrical characteristics during the hot-cold cycle, and more-so over a long period of time of many hot-cold cycles.
Very well designed and constructed metal-oxide resistors of the oxide formulae and assembly/construction used by Caddock -{and probably also by Vishay}- will work well for very long periods because those are designed and engineered to work in critical Military, Aerospace and Medical equipment applications.
L-pads versus fixed resistors
The problem with L-pads is that the resistive element wears thin after more than a few turns and to a greater degree than it does inside an amplifier's volume pot for the same number of turns,
because there is much higher electrical current flowing though an L-pad than through an amplifier's volume control in its quite different circuit position.
High current requires very large contact area to be maintained intact, and that is difficult to keep when a tight fitting contact point is continually moved over a deposited track of carbon or spiral of wire -{depending on the type of resistive element used in the L-pad}.
Over time L-pads cause lower quality sound as they wear out - I heard this in my own loudspeakers years ago, and eventually the L-pads connections became audibly intermitant.
Also, there is more heat generated as Power has to dissipated in an L-pad, and most are not made to sufficiently high power rating to have a very long life.
Use an L-pad to experiment in the design stage to find the best comprimise setting, then measure the resistances and substitute fixed wire-wound resistors of those values in place of the L-pad.
The problem with L-pads is that the resistive element wears thin after more than a few turns and to a greater degree than it does inside an amplifier's volume pot for the same number of turns,
because there is much higher electrical current flowing though an L-pad than through an amplifier's volume control in its quite different circuit position.
High current requires very large contact area to be maintained intact, and that is difficult to keep when a tight fitting contact point is continually moved over a deposited track of carbon or spiral of wire -{depending on the type of resistive element used in the L-pad}.
Over time L-pads cause lower quality sound as they wear out - I heard this in my own loudspeakers years ago, and eventually the L-pads connections became audibly intermitant.
Also, there is more heat generated as Power has to dissipated in an L-pad, and most are not made to sufficiently high power rating to have a very long life.
Use an L-pad to experiment in the design stage to find the best comprimise setting, then measure the resistances and substitute fixed wire-wound resistors of those values in place of the L-pad.
freQuence PCA caps
I emailed to freQuence a while ago and received a reply which includes a Specifications' list in English language.
The PCA caps are metalized polypropylene types, thus the dielectric is polypropylene.
There is little on the freQuence web-site about the assembly of the caps, thus it may not be equal to the very best,
but at their prices they will likely be as good as any other axial polypropylene cap at the same price, and may be better.
If anyone trys them, please do Post the audible results in comparison with what was previously used, and where used in the circuit.
alan-1-b said:
I emailed to freQuence a while ago and received a reply which includes a Specifications' list in English language.
The PCA caps are metalized polypropylene types, thus the dielectric is polypropylene.
There is little on the freQuence web-site about the assembly of the caps, thus it may not be equal to the very best,
but at their prices they will likely be as good as any other axial polypropylene cap at the same price, and may be better.
If anyone trys them, please do Post the audible results in comparison with what was previously used, and where used in the circuit.
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3 resistors or only 2 in each circuit ?
Hello Lucas,
as I was reading all the older Posts to see what I had not addressed, and if any other loose ends, I wondered whether you have installed 3 resistors for each crossover or only 2 ... ?
I intended 2 for the mid's filter - such as where you now have a 2ohm -{or 2.2 ohm ?}- plus a 2.7ohm with the 6uF cap
-{see #71 on Page 8 of this Thread - at the bottom of that Post}.
The 0.5ohm to the tweeter is the 3rd resistor.
If you have only a single resistor in the mid's filter and are happy with the sound result, then that is quite OK, but as you now have two spare 1.5ohm resistors you could try them in Series with the 6uF mid's cap if you have no resistor there - you may like that more or you may not.
Do Post how many resistors you have used, and where, so that others who find this Thread later can get some idea of what to expect.
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I'll not Post about inductors now, as you seem to be quite happy with the bass sound,
and the inductors currently in there are quite OK for sound until driven very hard with high volume playing to a greater degree than may be pleasant in your room.
New ones may not be any better for the volume levels you like, and its possible they may not produce as likeable sound at those volumes, though that will depend on the DCRs of whatever new inductors.
Hello Lucas,
as I was reading all the older Posts to see what I had not addressed, and if any other loose ends, I wondered whether you have installed 3 resistors for each crossover or only 2 ... ?
I intended 2 for the mid's filter - such as where you now have a 2ohm -{or 2.2 ohm ?}- plus a 2.7ohm with the 6uF cap
-{see #71 on Page 8 of this Thread - at the bottom of that Post}.
The 0.5ohm to the tweeter is the 3rd resistor.
If you have only a single resistor in the mid's filter and are happy with the sound result, then that is quite OK, but as you now have two spare 1.5ohm resistors you could try them in Series with the 6uF mid's cap if you have no resistor there - you may like that more or you may not.
Do Post how many resistors you have used, and where, so that others who find this Thread later can get some idea of what to expect.
****************************************************************************************************
I'll not Post about inductors now, as you seem to be quite happy with the bass sound,
and the inductors currently in there are quite OK for sound until driven very hard with high volume playing to a greater degree than may be pleasant in your room.
New ones may not be any better for the volume levels you like, and its possible they may not produce as likeable sound at those volumes, though that will depend on the DCRs of whatever new inductors.
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Strange, every single L-PAD I have ever disassembled was a concentric wirewound type with large sliding wipers. They can become intermittent over time, but this is usually because the wiper itself oxidizes. They usually clean up pretty nicely with a couple of rotations, and worst case seem to respond well to a dab of any good contact cleaner. (Caig Labs)
There are plenty of inexpensive, good quality L-PADS rated at 25W or 50W at Madisound, Parts Express, etc. In most applications except for extension speakers they will never see significant power levels in normal use. (A club would be the typical exception.) Most of the power in music is typically found in the lowest few octaves and most mid-range drivers and tweeters are reasonably efficient.
I've had 50yr old JBL speakers with the original L-PADs on the tweeters and they worked just fine.
You shouldn't be adjusting them on a regular basis after all the system response does not abruptly change - although changes in room furnishings and the like may have some minor influence.
L-PADs aren't ideal in other respects as there are several contacts in the signal path and arguably replacing these with a fixed attenuation L-PAD should result in better long term stability and just possibly a slight audible improvement. (I haven't heard any as long as I keep my adjustable L-PADS clean.)
I think the overall recommendation to replace the L-PAD with a fixed set of resistors is a good one though, just make sure that the LPAD reflects the proper resistance back to the X-O otherwise the performance of X-O itself will be compromised. (it is not a simple potentiometer see first link)
Note that you should probably measure the AC attenuation across the L-PAD in circuit (convert to dB) and then use one of the several online calculators to get the correct resistor values. Here's one:
L-PADS
And another:
L pad calculator - attenuation dB damping impedance decibel loudspeaker - sengpielaudio Sengpiel Berlin
These are the best I've found online so far..
L-pads
Thanks for Posting your experiences with L-pads Kevin !
- and it has reminded me that I should have mentioned I was discussing only variable-potentiometer types and not fixed resistor types,
nor even switched resistor types which its possible Lucas may have meant.
The variable-pot L-pads that deteriorated to unusable in my old loudspeakers were in the mid-driver circuit !
I probably tried a contact cleaner in them, as I did squirt contact cleaner in the pots in my electric guitar at times then -{until those deteriorated beyond salvation !}- however I have forgotten.
I have not seen the types in old JBL loudspeakers, and at the then JBL prices I would have thought longer life types would have been used.
I Posted about low-power rated types because that is what was in my old loudspeakers and in various low and mid-price loudspeakers I have seen since, and in particular I am Posting for UK buyers who don't want to buy from overseas' suppliers - for whatever reasons some have enquired such
of me - though I do buy from USA and elsewhere myself for what is not available in the UK.
I didn't adjust pot-type L-pads very often, but it seems some users do want a type they can adjust each time for different recordings they play,
but I think deciding a compromise fixed resistance is better for the long term, and if one owns an amplifier with tone-pots or filters it seems the adjustments are usually better done there.
Thankyou also for Posting the Links to the calculators.
I had not seen the second one previously, and I will look through that web-site when time is available.
www.lalena.com has an L-pad calculator in its audio pages, and it looks to be a correct one to me,
{though I have not used it as I always calculated using some mathematical formulae I found in a diy article in a magazine years ago}.
Do you have any comments about the Lalena site's calculator ?
Thanks for Posting your experiences with L-pads Kevin !
- and it has reminded me that I should have mentioned I was discussing only variable-potentiometer types and not fixed resistor types,
nor even switched resistor types which its possible Lucas may have meant.
The variable-pot L-pads that deteriorated to unusable in my old loudspeakers were in the mid-driver circuit !
I probably tried a contact cleaner in them, as I did squirt contact cleaner in the pots in my electric guitar at times then -{until those deteriorated beyond salvation !}- however I have forgotten.
I have not seen the types in old JBL loudspeakers, and at the then JBL prices I would have thought longer life types would have been used.
I Posted about low-power rated types because that is what was in my old loudspeakers and in various low and mid-price loudspeakers I have seen since, and in particular I am Posting for UK buyers who don't want to buy from overseas' suppliers - for whatever reasons some have enquired such
of me - though I do buy from USA and elsewhere myself for what is not available in the UK.
I didn't adjust pot-type L-pads very often, but it seems some users do want a type they can adjust each time for different recordings they play,
but I think deciding a compromise fixed resistance is better for the long term, and if one owns an amplifier with tone-pots or filters it seems the adjustments are usually better done there.
Thankyou also for Posting the Links to the calculators.
I had not seen the second one previously, and I will look through that web-site when time is available.
www.lalena.com has an L-pad calculator in its audio pages, and it looks to be a correct one to me,
{though I have not used it as I always calculated using some mathematical formulae I found in a diy article in a magazine years ago}.
Do you have any comments about the Lalena site's calculator ?
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Do you know what, Alan, I've tried equivalent values between MOX and Welwyn wirewound, and the MOX sound much nicer, in my opinion. They sound freer and more musical. I think I may revert back to them.
Regarding values, I have 0R5 in the tweeter and in the mids I have 2R7 after the 6uF (to earth), with 2R2 immediately after the 33uF, but I am not entirely happy with the mids. I want them a touch louder generally, and less tight sounding. I may swap the 2R2 for a 1R5 and the 2R7 for a 2R2. I'm going back to MOX too. Sorry if that's dumb, but to my ears they are better sounding. I expect that to be near the end of the resistor road for me. I hope so anyway, as I need a completed reference speaker for when I reassemble and test my amp.
All the best
Lucas
compromises
Its not "dumb" to use the type of resistor that one prefers the sound of !
Given that you have hearing capability to discern the difference between the sounds of the two types, you may as well use the type you prefer.
I posted the warning about MOX type resistors because I cannot guarantee they will remain sounding the same after a long period of use, for the reasons I gave.
My consideration was, because you had previously requested low price components, I thought you wanted a resistor that would not need replacing after a period of hot/cold cycling, and that is what a lot of low budget listeners ask me to recommend.
As for sound quality, well you will know that some enthusiasts use valve{tube} amplifiers because they prefer the sound even though valves wear out and have to be replaced.
Some other listeners do prefer the sound from valve amplifiers but say they cannot afford the maintainance costs of replacing valves, so they buy solid state.
It is often difficult for me to know what to recommend because of this Cost versus Performance trade-off, thus I play it safe and recommend long-life components unless I am asked to recommend otherwise.
For resistors the only oxide types I am confident to recommend for long life are those manufactured by Caddock.
There is audible differences between different types of wirewounds, even between different Series from the same manufacturer.
Please Post and tell us for the use of all readers, which Welwyns did you try -
W__ series, or WA__ series, or WP__ series, or another series of theirs ?
And the MOX type you prefer, which Manufacturer's name is stamped on them ?
or if no known manufacturer, then which Company did you buy them from ?
If you have bought a sufficiently high power rated MOX it will not get hot whilst music signal through it and thus, if it has been well constructed, it's connection contacts may not deteriorate and the sound may remain as good as when new for a very long time.
I prefer Mills brand wirewounds over other wirewound brands I have heard, but some diyers do not want to pay the price for those, and in the UK only the very large 12watt Mills are available and some UK diyers will not buy via Mailorder from USA to obtain the smaller size 5watt Mills, thus why I recommend Welwyn for them, if they want long life.
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For slightly louder mids, do try the 1R5 after the 33uF cap, but retain the 2R7 to ground after the 6uF cap because lower resistance of 2R2 there will cause small attenuation of part of the midrange, however if you wish to hear the nature of the differences then do try both and listen for what you prefer, as you have resistors in all these values now.
Its not "dumb" to use the type of resistor that one prefers the sound of !
Given that you have hearing capability to discern the difference between the sounds of the two types, you may as well use the type you prefer.
I posted the warning about MOX type resistors because I cannot guarantee they will remain sounding the same after a long period of use, for the reasons I gave.
My consideration was, because you had previously requested low price components, I thought you wanted a resistor that would not need replacing after a period of hot/cold cycling, and that is what a lot of low budget listeners ask me to recommend.
As for sound quality, well you will know that some enthusiasts use valve{tube} amplifiers because they prefer the sound even though valves wear out and have to be replaced.
Some other listeners do prefer the sound from valve amplifiers but say they cannot afford the maintainance costs of replacing valves, so they buy solid state.
It is often difficult for me to know what to recommend because of this Cost versus Performance trade-off, thus I play it safe and recommend long-life components unless I am asked to recommend otherwise.
For resistors the only oxide types I am confident to recommend for long life are those manufactured by Caddock.
There is audible differences between different types of wirewounds, even between different Series from the same manufacturer.
Please Post and tell us for the use of all readers, which Welwyns did you try -
W__ series, or WA__ series, or WP__ series, or another series of theirs ?
And the MOX type you prefer, which Manufacturer's name is stamped on them ?
or if no known manufacturer, then which Company did you buy them from ?
If you have bought a sufficiently high power rated MOX it will not get hot whilst music signal through it and thus, if it has been well constructed, it's connection contacts may not deteriorate and the sound may remain as good as when new for a very long time.
I prefer Mills brand wirewounds over other wirewound brands I have heard, but some diyers do not want to pay the price for those, and in the UK only the very large 12watt Mills are available and some UK diyers will not buy via Mailorder from USA to obtain the smaller size 5watt Mills, thus why I recommend Welwyn for them, if they want long life.
**************************************************
For slightly louder mids, do try the 1R5 after the 33uF cap, but retain the 2R7 to ground after the 6uF cap because lower resistance of 2R2 there will cause small attenuation of part of the midrange, however if you wish to hear the nature of the differences then do try both and listen for what you prefer, as you have resistors in all these values now.
same as Lucas
Hi all: I hve studied both threads intensively. My project same as Lucas', except with the MK 2 printed circuit board. Have pretty much deciphered all the info I was looking for except for 2 things. What was ever decided on as the best *compromis* resister values for the mid filter? bearing in mind I am dealing with a 24 vs 33 cap and a 4 vs 6 cap. Are the 2.7 and 2.2 r's that Lucas used applicable to my xover? Should they be higher or lower?
Sorry if I missed seeing this if it exists. So many pages so many times.
Comments. Dont need to start all the whys & howcomes over
Thanks
Hi all: I hve studied both threads intensively. My project same as Lucas', except with the MK 2 printed circuit board. Have pretty much deciphered all the info I was looking for except for 2 things. What was ever decided on as the best *compromis* resister values for the mid filter? bearing in mind I am dealing with a 24 vs 33 cap and a 4 vs 6 cap. Are the 2.7 and 2.2 r's that Lucas used applicable to my xover? Should they be higher or lower?
Sorry if I missed seeing this if it exists. So many pages so many times.
Comments. Dont need to start all the whys & howcomes over
Thanks
Your circuit's capacitors ?
Are you telling us that the 2 capacitors in the midrange filter's circuit are different in your 44s than in Lucas' ?
I am aware of an original and a MkII version of the 44, but rather than me speculate, please Post the actual capacitor values in your 44s ... ?
Values for ESR compensation resistors are a Compromise.
Post whether you prefer to have the upper-midrange response prominent,
or the lower midrange response prominent for your listening ... ?
Note, this does not mean that part of the midrange has to be recessive - of lower output than the other areas of the frequency spectrum.
Describe the current balance of the frequency spectrum in your 44s,
of treble versus upper midrange versus lower midrange versus bass,
and what you would like to change in that balance ... ?
Are you telling us that the 2 capacitors in the midrange filter's circuit are different in your 44s than in Lucas' ?
I am aware of an original and a MkII version of the 44, but rather than me speculate, please Post the actual capacitor values in your 44s ... ?
Values for ESR compensation resistors are a Compromise.
Post whether you prefer to have the upper-midrange response prominent,
or the lower midrange response prominent for your listening ... ?
Note, this does not mean that part of the midrange has to be recessive - of lower output than the other areas of the frequency spectrum.
Describe the current balance of the frequency spectrum in your 44s,
of treble versus upper midrange versus lower midrange versus bass,
and what you would like to change in that balance ... ?
Hi all,
The Mk2 (PCB crossover) Midrange caps are different in that mine were 25uF with an 8uF in parallel. I have a friend whose Mk1 (black front, p2p wired x-over) 25uF caps had no paralleled 8uF, so I guess at some point they decided to go to 25uF. Which is the better solution, however, is not so clear. I am happy with my 33uF caps.
I think you'll be very pleased you've done this. Replacing caps is not as simple as all that. The suggestion of not using ESR resistors at all was quickly put to bed at first listen - the sound was simply excruciatingly awful!
My current set-up for ESR compensating resistors is as follows:
In the treble circuit, replacing film caps with polypropylene film caps, almost no compensation is technically required. I found, however, that a 0.5 Ohm 2 watt wire-wound resistor in series after the last cap attenuated the tweeters which are now much much cleaner and sweeter and seem brighter. The 0.5 helps keep the tonal balance I feel.
In the mids, I have a 2.2 Ohm 4W wire-wound in series immediately after 33uF and a 2.7 Ohm 4W wire-wound in series immediately after 6uF to earth.
For the bass I replaced old electros with new electros, so no ESR compensation here. The cost of 4x huge polyprops is hard to justify here, especially for the bass circuits, where the sensible money would first go on new air-core inductors if anything.
This set-up works well if your amp can produce good bass. I have a cheap Onkyo amp that I originally tested the amendments to ESR with and they made the speakers sound very bass light, which is a shame because the big easy bass is a big part of the appeal with these speakers. I considered what to do with ESR to improve bass, but fortunately it resolved itself as the issue was with the bass-shy amp. My newly built amp reintroduced the bass to give a lovely balanced sound and so I recommend the values I have now. They do sound quite special now - cleaner and crisper.
I hope that helps. All praise to Alan though - not me!
Lucas
The Mk2 (PCB crossover) Midrange caps are different in that mine were 25uF with an 8uF in parallel. I have a friend whose Mk1 (black front, p2p wired x-over) 25uF caps had no paralleled 8uF, so I guess at some point they decided to go to 25uF. Which is the better solution, however, is not so clear. I am happy with my 33uF caps.
I think you'll be very pleased you've done this. Replacing caps is not as simple as all that. The suggestion of not using ESR resistors at all was quickly put to bed at first listen - the sound was simply excruciatingly awful!
My current set-up for ESR compensating resistors is as follows:
In the treble circuit, replacing film caps with polypropylene film caps, almost no compensation is technically required. I found, however, that a 0.5 Ohm 2 watt wire-wound resistor in series after the last cap attenuated the tweeters which are now much much cleaner and sweeter and seem brighter. The 0.5 helps keep the tonal balance I feel.
In the mids, I have a 2.2 Ohm 4W wire-wound in series immediately after 33uF and a 2.7 Ohm 4W wire-wound in series immediately after 6uF to earth.
For the bass I replaced old electros with new electros, so no ESR compensation here. The cost of 4x huge polyprops is hard to justify here, especially for the bass circuits, where the sensible money would first go on new air-core inductors if anything.
This set-up works well if your amp can produce good bass. I have a cheap Onkyo amp that I originally tested the amendments to ESR with and they made the speakers sound very bass light, which is a shame because the big easy bass is a big part of the appeal with these speakers. I considered what to do with ESR to improve bass, but fortunately it resolved itself as the issue was with the bass-shy amp. My newly built amp reintroduced the bass to give a lovely balanced sound and so I recommend the values I have now. They do sound quite special now - cleaner and crisper.
I hope that helps. All praise to Alan though - not me!
Lucas
ESR resistors, and capacitors, and Celestion 66 thread
Hi DM,
Celestion used the same PCB for both 44 and 66 because both use the same circuit configuration, even though some different capacitor values in each.
For maximising upper mids, use 3.9ohm in Series with the 4uF cap -{and that is likely the maximum ESR that would have been in the original cap in the upper mids}- as that will reduce the filtering roll-off of upper mids.
I would start with whatever resistors I had on-hand.
If you have a 3.3ohm then try that with the 4uF cap.
If you have a 1ohm or 1.2ohm then try either in Series with the 24uF cap,
but I would start with 1.5ohm there,
so if you are buying, buy 1.5ohm and 3.9ohm.
Perhaps buy cheap 5watt wirewounds from a local shop to try, to hear if those values give close to the frequency balance you want.
If a little too much upper mids, then reduce the 3.9 to 3.3 or even to 2.7ohm, but if you go lower than about 2.7 ohm then you may start to hear a narrow-band midrange resonance via the mid-dome.
I posted why that occurs ... some where in the 66 thread ...
To reduce mids overall, increase the 1.5ohm to 1.8 or 2.2 or 2.7 until you hear close to what you are wanting - but with 3.9ohm to the 4uF cap to retain upper mids, and then reduce to 3.3 or 2.7 there if necessary after listening.
After that, then buy a good quality 5watt non-inductive resistor for the 24uF application.
The 4uF application does not need a non-inductive BUT it does need a quality manufactured resistor so that voltage annomolies resulting from poorly constructed resistors do not couple into the mid-dome's signal.
The sound should be clearer or cleaner with the better resistors than with the cheap ones you experiment first with,
BUT, please do Post your listening results about resistors' quality - in the 66 Thread - because that is useful to other restorers.
Post also the brand and type of capacitors you are using for each filter section of the crossover.
From where you seem to be located you will likely be able to buy Mills MRA-5 non-inductive wirewounds via Mail-order easily,
and those are fine for both resistor locations.
The Mr_White , Celestion 66 thread is alive and well.
I am currently discussing other capacitors, and the eventual ESR resistor to his 25uF Series midrange cap, with a critical listener there.
After you have decided your preferred resistor values, go to Post #349 on Page 35 of that Thread and try the EXPERIMENT I described there-in.
Then tell us there what you prefer !
Hi DM,
Celestion used the same PCB for both 44 and 66 because both use the same circuit configuration, even though some different capacitor values in each.
For maximising upper mids, use 3.9ohm in Series with the 4uF cap -{and that is likely the maximum ESR that would have been in the original cap in the upper mids}- as that will reduce the filtering roll-off of upper mids.
I would start with whatever resistors I had on-hand.
If you have a 3.3ohm then try that with the 4uF cap.
If you have a 1ohm or 1.2ohm then try either in Series with the 24uF cap,
but I would start with 1.5ohm there,
so if you are buying, buy 1.5ohm and 3.9ohm.
Perhaps buy cheap 5watt wirewounds from a local shop to try, to hear if those values give close to the frequency balance you want.
If a little too much upper mids, then reduce the 3.9 to 3.3 or even to 2.7ohm, but if you go lower than about 2.7 ohm then you may start to hear a narrow-band midrange resonance via the mid-dome.
I posted why that occurs ... some where in the 66 thread ...
To reduce mids overall, increase the 1.5ohm to 1.8 or 2.2 or 2.7 until you hear close to what you are wanting - but with 3.9ohm to the 4uF cap to retain upper mids, and then reduce to 3.3 or 2.7 there if necessary after listening.
After that, then buy a good quality 5watt non-inductive resistor for the 24uF application.
The 4uF application does not need a non-inductive BUT it does need a quality manufactured resistor so that voltage annomolies resulting from poorly constructed resistors do not couple into the mid-dome's signal.
The sound should be clearer or cleaner with the better resistors than with the cheap ones you experiment first with,
BUT, please do Post your listening results about resistors' quality - in the 66 Thread - because that is useful to other restorers.
Post also the brand and type of capacitors you are using for each filter section of the crossover.
From where you seem to be located you will likely be able to buy Mills MRA-5 non-inductive wirewounds via Mail-order easily,
and those are fine for both resistor locations.
The Mr_White , Celestion 66 thread is alive and well.
I am currently discussing other capacitors, and the eventual ESR resistor to his 25uF Series midrange cap, with a critical listener there.
After you have decided your preferred resistor values, go to Post #349 on Page 35 of that Thread and try the EXPERIMENT I described there-in.
Then tell us there what you prefer !
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44's mid-cone drivers ? , and etc ...
Hi Lucas,
If your friend's board has still the old capacitors, look very closely to see if any evidence of a parallel connected cap having been de-soldered from the original 24uF cap.
Another possibility:-
take a midrange cone driver out of his and compare it visually to one of yours.
If the cones themselves are visually different, or with different termination material surrounds, then a different value capacitor may have been required for the correct cross-over frequency,
and/or,
if the sizes of the magnets on the back of the drivers' chassis are different, then almost certainly a different cap value would have been required.
But, if his mid-drivers are identical to yours he can try 33uf there if he wants to, but if that worries him then simply use a new 25uF cap there, or use a 27uF cap for a least a little additional low mids' weight, unless he prefers the 25uF sound.
Post and tell us about the actual midrange driver in each version, as this will be useful to other restorers.
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The "seem brighter" -{in addition to "cleaner and sweeter"}- from the 0.5ohm resistor terminated tweeters is likely a psychoacoustic effect resulting from closer matching of the transient response of the tweeter to the midrange as result of the resistor ... and possibly better displaying the quality of the capacitors you used.
The "4W" wirewounds you have installed in the mids, are those Welwyn's WP series ?
or another Welwyn series ?
or another brand ?
*************************************************************
Electros in the bass filter cause part of the bass and low-mids' sound, and if you like that then it is fine.
I have discussed this with dloper in the 30s' pages of the Celestion 66 thread.
The types, and the DCRs, of the inductors also cause part of the bass sound,
thus if you decide to spend significant money to try to get another specific sound in the bass later Post here if you want to discuss possibilities.
If you currently have low resistance in the cored inductors, but buy air-core inductors of higher resistance the sound will change but perhaps not in the way you may want.
The old cored inductors are fine for low to medium volume levels,
but will cause a noticeable change of sound if driven harder.
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Regardless of what Onkyo may achieve with some of their premium models of amplifiers, their cheap models are not usually wonderful, as you can hear !
For anyone wanting reasonably good quality sound bass extension from a low priced amplifier, try the basic Rotel current or recent models.
Given the general Rotel sound of recent years, though it is a bit different between models, I think they are a suitable minimum amplifier to use with the classic Celestion 44s and 66s, if one cannot build or afford substantially better.
Some past NAD cheap models were OK in the bass, and perhaps their current model is, however I have not heard a sample.
Lucas's description of the differences in bass quality when using different amplifiers is very good - particually as relevant for these loudspeakers.
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Thankyou for your compliment Lucas !
and, your reports of changes to the sound and the descriptions of your modifications are also worthy of note because this is one of the ways we learn things.
With Celestion 44, the "EXPERIMENT" I describe in Post #349 on Page 35 of the Celestion 66 midrange Thread can also be tried.
Hi Lucas,
If your friend's board has still the old capacitors, look very closely to see if any evidence of a parallel connected cap having been de-soldered from the original 24uF cap.
Another possibility:-
take a midrange cone driver out of his and compare it visually to one of yours.
If the cones themselves are visually different, or with different termination material surrounds, then a different value capacitor may have been required for the correct cross-over frequency,
and/or,
if the sizes of the magnets on the back of the drivers' chassis are different, then almost certainly a different cap value would have been required.
But, if his mid-drivers are identical to yours he can try 33uf there if he wants to, but if that worries him then simply use a new 25uF cap there, or use a 27uF cap for a least a little additional low mids' weight, unless he prefers the 25uF sound.
Post and tell us about the actual midrange driver in each version, as this will be useful to other restorers.
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The "seem brighter" -{in addition to "cleaner and sweeter"}- from the 0.5ohm resistor terminated tweeters is likely a psychoacoustic effect resulting from closer matching of the transient response of the tweeter to the midrange as result of the resistor ... and possibly better displaying the quality of the capacitors you used.
The "4W" wirewounds you have installed in the mids, are those Welwyn's WP series ?
or another Welwyn series ?
or another brand ?
*************************************************************
Electros in the bass filter cause part of the bass and low-mids' sound, and if you like that then it is fine.
I have discussed this with dloper in the 30s' pages of the Celestion 66 thread.
The types, and the DCRs, of the inductors also cause part of the bass sound,
thus if you decide to spend significant money to try to get another specific sound in the bass later Post here if you want to discuss possibilities.
If you currently have low resistance in the cored inductors, but buy air-core inductors of higher resistance the sound will change but perhaps not in the way you may want.
The old cored inductors are fine for low to medium volume levels,
but will cause a noticeable change of sound if driven harder.
*************************************************************
Regardless of what Onkyo may achieve with some of their premium models of amplifiers, their cheap models are not usually wonderful, as you can hear !
For anyone wanting reasonably good quality sound bass extension from a low priced amplifier, try the basic Rotel current or recent models.
Given the general Rotel sound of recent years, though it is a bit different between models, I think they are a suitable minimum amplifier to use with the classic Celestion 44s and 66s, if one cannot build or afford substantially better.
Some past NAD cheap models were OK in the bass, and perhaps their current model is, however I have not heard a sample.
Lucas's description of the differences in bass quality when using different amplifiers is very good - particually as relevant for these loudspeakers.
*************************************************************
Thankyou for your compliment Lucas !
and, your reports of changes to the sound and the descriptions of your modifications are also worthy of note because this is one of the ways we learn things.
With Celestion 44, the "EXPERIMENT" I describe in Post #349 on Page 35 of the Celestion 66 midrange Thread can also be tried.
No 8uF removed. They came like that. I've seen other 44 x-overs that were a single 25uF too. My 8uF parallel was factory fitted too, as it is the same brand as other 72uFs fitted elsewhere in the circuits.
I won't be able to remove them to compare, but they certainly look identical. they may have different magnet sizes - it's possible. I reckon that they just responded to reviews or feedback, and changed caps in response to give a different sound.
I meant that they seemed brighter and cleaner/sweeter than the old original caps. The resistor did nothing I could hear but attenuate them a touch.
They're the Welwyn WP series, as you recommended. My previously stated preference for MOX resistors was just nonsense from me in response to multiple alterations and my making assumptions about what caused what effect. The Welwyns are good.
I'd certainly never buy an Onkyo again, that's for sure - this one is 20 years old - I was a teenager! In fact, I'd only ever recommend a Pass Labs B1 pre and F5 power combination these days. It seems that for about £150 you can make an amp that is almost flawless. I have the B1 already. It is superb! The F5 is my next project for January 2010
I'll check that out. Thanks Alan. As always, your commitment is compelling!
Lucas
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