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Crossovers for the New Advent Loudspeaker


Guest One-Shot Scot

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Guest One-Shot Scot

My primary interest is in the New Advent Loudspeaker, models A3, U3, A4 and U4. With two exceptions, I have found that the New Advent crossovers contain the following components, attached to a quarter-inch thick, 4.75" x 4.75" piece of Masonite:

1 Non-inductive resistor, 1 ohm.

1 Non-inductive resistor, 1.5 ohm.

1 Capacitor, non-polarized 13uF

1 Three-position tweeter switch

4 Speaker connectors, which appear to be 20-gauge aluminum wire.

1 Inductor, specifications presently unknown. (I would appreciate hearing from anyone who knows the inductance value and DCR (ohms) rating of the original New Advent inductor.)

I have measured the values of original Advent capacitors and resistors and found most of them do not match their original specifications. The values of the capacitors were usually too low. The values of the resistors were variable and two didn't work at all. Therefore, rebuilding the original New Advent crossovers is a necessity, if the original New Advent sound is to be equaled or exceeded.

The A3 and U3 crossovers have thinner speaker connection wires than the A4 and U4 crossovers. It looks like the gauge of the actual wires is the same on both series of crossover models, but the plastic insulation on the A4 and U4 crossovers is thicker. Also, there are minor layout differences in the way the capacitor and resistors are connected between the A3 and U3 models when compared to the A4 and U4 models.

It seemed to me that the use of 18-gauge stranded copper wire would be a good rebuilding choice, considering the gauge of the wires used in the original inductors, capacitors and resistors. Dayton resistors seemed almost identical to the ones used in the original crossovers.

My problem was in deciding what to do about replacing the 13uF capacitor, which doesn't seem to be manufactured any more.

Some say that substituting a 12uF capacitor for the original 13uF part is good enough and will only slightly alter the crossover frequency. Others say that two capacitors whose combined value equals 13uF are a better choice. But what values should be combined? A value from each end of the spectrum, such as a 12uF and a 1uF? Or, would it be better to use two capacitors of nearly equal value, such as a 6.2uF and a 6.8uF? I decided to go with the 6.2uF and a 6.8uF combination and I chose Solen over Dayton because the tolerance for the Dayton caps is 10% and the Solens are rated at 5%.

Apparently, even Advent had problems locating 13uF capacitors at the end of the New Advent production run in the early 1980s. Two A4 speakers that I bought at this time (A4 47882 and A4 47681) had crossovers which each contained a 12uF and a 1uF capacitor wired together. Advent used inexpensive components in its crossovers as a cost-cutting strategy. But, rather than use a single 12uF cap, Advent went to the added expense of wiring in an additional 1uF cap in order to create the necessary 13uF value which would maintain the desired 1500Hz crossover frequency. My thinking is that if Advent went to all to this trouble to obtain its 13uF capacitor specification, I should do the same.

Here is a link to a web page I made which shows original A3 and A4 crossovers, an A3 crossover which I rebuilt and an original A4 crossover which contains both a 12uF and a 1uF capacitor:

http://home.comcast.net/~newadvent/NewAdventCrossovers.html

I would like to make a crossover for the New Advent speaker which would leave out the 3-position switch. I am asking for information, and advice on how to better rebuild New Advent crossovers as well as how to make new ones.

One-Shot Scot

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Hi there;

I will write more if they did use aluminum wire in the speakers.

Going the extra yard, I would buy a capacitor with the closest uf rating and measure to see if it close to the specified original value and buy 2 sets.

If the original is, for just an example 6uf, then if you can find a 5.9uf and it measures at 6uf then buy a matched set of 2, if you have two speakers.

If you are stuck like a lot of members and need to mailorder them, then I would suggest ordering the combined value of 6uf whether they are different values or not, do not worry.

The sonic difference will quite probably not be noticeable by most people.

Good luck.

You will quite likely only do the capacitor change once in your lifetime, don't worry about a few dollars spent now.

Good luck.

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Another xover combination to consider for improved sonics is a 12 uF pp cap bypassed by a series connected 1 uF film/foil cap. It looks in your pics like you didn't replace those cheap, sand cast resistors. I recommend you do with non-inductive, wire wound audio grade resistors. Parts Express sells them for about $3.50 each.

There are earlier posts in the Advent area in which I advised another poster how to eliminate the switch. Use the search tool to locate it. It's about 1 month old now.

Remember, it's all about the music

Carl

Carl's Custom Loudspeakers

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Guest One-Shot Scot

<

There are earlier posts in the Advent area in which I advised another poster how to eliminate the switch. Use the search tool to locate it. It's about 1 month old now.>>

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Carl:

Thanks for the reply.

You're right, I replaced the original, cheap, sand-cast resistors with new, cheap, sand-cast resistors. In view of the overall quality of the Advent woofer and tweeter, I thought that the Dayton resistors would be a good choice because they appear to be exactly the same as the originals. Yet, following through with this logic would require that I use other parts which closely match the originals, such as $0.60 electrolytic capacitors and 20-gauge aluminum wire.

If the Mills resistors will give better results, I will do an upgrade. After all, I will only be out the $2.50 per crossover that I spent on the Daytons.

It looks like the back sides of the original Advent crossover boards were smeared with glue and then pressed over the rear hole in the cabinet. Getting these crossovers out of the cabinet without damaging them takes a lot of skill and patience. Therefore, when I put the crossovers back into the cabinet, I run a bead of hot glue around the outer edge of the crossover board. This method creates an air tight seal, while still allowing the crossover to be easily removed for repairs or replacement.

I am going to do some more research on the capacitor bypass idea that you mentioned. In the meantime, do you think that combining a 6.2uF with a 6.8uF capacitor is better than combining a 12uF with a 1uF?

Thanks,

One-Shot Scot

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Guest One-Shot Scot

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Vern:

My main concern was to keep the original Advent capacitor value at 13uF so that the crossover frequency would be as close to 1500Hz as possible. If my understanding is correct, using a 12uF capacitor would push the crossover frequency up to somewhere around 1650Hz.

Unfortunately, I have to purchase all of my electrical components from mail order companies, so it is impossible for me to bench test any parts.

Thanks,

One-Shot Scot

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Guest twist72

I just upgraded my caps in a pair of U3 Advents. I used the Dayton 6.2uf and 6.8uf in Parallel. Works fine and sounds great. BTW the Daytons are rated @ 5% tolerance. Saved alittle money but not much over the Solens.

I also went through PartsExpress, highly recommended!

As far as resistors went, I checked all of mine and they were actually a tad higher than rated. I didnt feel it much of a concern since both sets seemed very close and I left them be. I did redo the conection with the yellow wire and the ends of the two resistors. The copper(?)clip that held the conection together was corroded and looked very cheap. I just clipped it and used some 60/40 solder to hold things together.

Todd

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>

>sonics is a 12 uF pp cap bypassed by a series connected 1 uF

>film/foil cap. It looks in your pics like you didn't replace

>those cheap, sand cast resistors. I recommend you do with

>non-inductive, wire wound audio grade resistors. Parts Express

>sells them for about $3.50 each.

>There are earlier posts in the Advent area in which I advised

>another poster how to eliminate the switch. Use the search

>tool to locate it. It's about 1 month old now.>>

>

>>

>

>>

>>

>

>

>Carl:

>

>Thanks for the reply.

>

>You're right, I replaced the original, cheap, sand-cast

>resistors with new, cheap, sand-cast resistors. In view of the

>overall quality of the Advent woofer and tweeter, I thought

>that the Dayton resistors would be a good choice because they

>appear to be exactly the same as the originals. Yet, following

>through with this logic would require that I use other parts

>which closely match the originals, such as $0.60 electrolytic

>capacitors and 20-gauge aluminum wire.

>

>If the Mills resistors will give better results, I will do an

>upgrade. After all, I will only be out the $2.50 per crossover

>that I spent on the Daytons.

>

>It looks like the back sides of the original Advent crossover

>boards were smeared with glue and then pressed over the rear

>hole in the cabinet. Getting these crossovers out of the

>cabinet without damaging them takes a lot of skill and

>patience. Therefore, when I put the crossovers back into the

>cabinet, I run a bead of hot glue around the outer edge of the

>crossover board. This method creates an air tight seal, while

>still allowing the crossover to be easily removed for repairs

>or replacement.

>

>I am going to do some more research on the capacitor bypass

>idea that you mentioned. In the meantime, do you think that

>combining a 6.2uF with a 6.8uF capacitor is better than

>combining a 12uF with a 1uF?

>

>Thanks,

>

>One-Shot Scot

>

>

I think your best bet is to go the bypass route. It's the most common xover technique used.

Remember, it's all about the music

Carl

Carl's Custom Loudspeakers

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Guest One-Shot Scot

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Todd:

Thanks for the confirmation that using the 6.2uF and 6.8uF combination was a good one.

I would like to know for certain that the 5% tolerance specification for Dayton capacitors is correct. Parts Express has stated both 5% and 10% tolerance specifications concerning Dayton capacitors:

"250 VDC * 5% tolerance * High purity * High current capacity * Specially designed for crossovers."

http://www.partsexpress.com/webpage.cfm?&WebPage_ID=61

"All values are rated at 250 VDC, 10% tolerance."

http://www.partsexpress.com/webpage.cfm?&DID=7&WebPage_ID=69

250 VDC

5% tolerance

High purity

High current capacity

http://www.partsexpress.com/pe/pshowdetl.c...tNumber=027-424

On page 138, the Parts Express catalog (#25, 2006) says that Dayton Metallized Polypropylene Capacitors have the following attributes: "All values are rated at 250 VDC, 10% tolerance."

So, with this amount of confusion in regard to the tolerance specification of Dayton capacitors, I chose the Solens.

Have you measured the values of the Dayton capacitors and found them to be within 5% of their stated specifications? If so, I will consider using Dayton capacitors.

One-Shot Scot

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Guest One-Shot Scot

>Hi again;

>

>Sorry, but I am having a problem in reading you refer to the

>wire as aluminum.

>

>Are you certain you have aluminum wires?

Well, I don't claim to be a metallurgist, but the wires that I have removed from all New Advent A4/U4 and A3/U3 crossovers appear to be made of aluminum. I could be wrong.

The wires on the A3/U3 crossovers do appear to be of a smaller gauge than those of the A4/U4 crossovers. However, this difference in size seems to be due to the thicker insulation which was used in the A4/U4 crossovers. I have noticed that the wires on the A4/U4 crossovers seem to be more brittle than those on the A3/U3 crossovers and tend to break off very easily from their solder points.

Here is a picture that I took of some A4 crossover wires:

http://home.comcast.net/~newadvent/cabinet...dventWires.html

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>>Hi again;

>>

>>Sorry, but I am having a problem in reading you refer to

>the

>>wire as aluminum.

>>

>>Are you certain you have aluminum wires?

>

>

>Well, I don't claim to be a metallurgist, but the wires that I

>have removed from all New Advent A4/U4 and A3/U3 crossovers

>appear to be made of aluminum. I could be wrong.

>

>The wires on the A3/U3 crossovers do appear to be of a smaller

>gauge than those of the A4/U4 crossovers. However, this

>difference in size seems to be due to the thicker insulation

>which was used in the A4/U4 crossovers. I have noticed that

>the wires on the A4/U4 crossovers seem to be more brittle than

>those on the A3/U3 crossovers and tend to break off very

>easily from their solder points.

>

>Here is a picture that I took of some A4 crossover wires:

>

>http://home.comcast.net/~newadvent/cabinet...dventWires.html

>

>

Hi there;

The reason I question about the aluminum wire is all the problems that have been created in its use.

Aluminum wire is used probably by every electrical utility company to carry our hydro power to every house's service panel in North America.

It is cheaper than the superior copper wire, buts needs to needs to be a larger guage to carry adequate current.

Connections are very critical as aluminum oxidizes (tarnishes) at all connections unless chemically treatd.

In residences here, a paste is applied to the connections to prevent oxidation.

In homes here during around the 1960 -70's aluminum wire was used to wire single family dwellings.

In a safety magazine in early 1974 I read that there was 1/4 million known house fires known to be caused by aluminum wire.

No records were kept for homes where only partial homes were wired with aluminum wire.

The aluminum wire here was 12 guage solid versus the normal 14 guage copper solid conductor.

Regular light switches, outlets and Marrettes (electrical connectors) were compatible with copper connections.

Aluminum wire was not a problem initally, after a period of time the problems started showing up.

If anyone should find that they have aluminum house wire, they probably find that some lights, outlets or appliances fail to work.

You should seriously look into preventative maintenance, soon.

I have seen a few scarey situations in my work.

Polybutylene plastic piping, Urea foam insulation, and aluminum house wire are just a few issues that have popped up during my work life.

Aluminum solid wire can also be nicked and it tends to break at that point.

Aluminum wire can be soldered, I have a real old bar of aluminum solder from Sears Roebuck, probably 50 years old.

A riveted connection is good when freshly done, but being soft aluminum wire can crush and oxidation can ooze into that connection.

I have never read anywhere where aluminum wire was used inside speaker enclosures, but, aluminum voice coil wires have been used by numerous companies.

Weight, cost, ability to cool better than copper, easier on the machinery, who knows.

After all this rattle, I would suggest, if there is aluminum wires within the enclosures, replace with stranded copper wire, perhaps 14 guage or better.

Solder all connections, and don't use the original, Marr twist on connectors used in some speakers systems.

You don't need a highend silver solder, a low alloy of silver is reasonably available today, use safety glasses and ventilation cautions.

Good luck.

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Another brief rattle;

I came across a 2 speed fan motor one time that was shaking a house furnace like crazy.

I took the fan door off to see there was a glow inside the terminal end of the motor.

Back, maybe in the 1960's, fractional motor companies started using a copper colour lacquered aluminum motor winding wire, to replace the more expensive copper wire.

The motor housings went from being heavy cast iron with minimal ventilation openings, to steel heavily ventilated openings with aluminum bell ends.

The call I was on, I had installed the 2 speed motor a few years earlier.

The glow was one end of the winding wires, where they still used a brass crimpon connector to fasten the lead to the circuit board connection.

The motor would start and the connection would glow and the motor would stop, to let it cool down, it appeared to be like a blinking flashlight.

The connector and circuit borard connections were almost melted but still functioning on an off and on basis.

If the motor was typical of the hairy motors I have come across, because of poor or no air filtration, a house fire was pending.

I only saw one of these examples and once is scarey enough.

When you've seen how burnt a woofers voice coil can become, charred, toast, you try to err the side of caution.

Good luck.

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Scot, scrape those bare, aluminum appearing wires with a knife. If the wire stays silver all the way through, it could be aluminum. If you hit copper coloring, it is, well, copper :^). Tinned copper.

I agree with Vern that it does seem strange that they would have used aluminum wire in speakers. However, these were made in the late seventies when interest rates and inflation were at nauseating levels and many companies tried many different things to save money. So who knows?

I have a friend who bought a house that was built in 1978 and when he went to replace the soffits and face boards on the roof edges because they were falling apart, he found that they were made of compressed cardboard!

Doug

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Guest One-Shot Scot

>Scot, scrape those bare, aluminum appearing wires with a

>knife. If the wire stays silver all the way through, it could

>be aluminum. If you hit copper coloring, it is, well, copper

>:^). Tinned copper.

>

>I agree with Vern that it does seem strange that they would

>have used aluminum wire in speakers. However, these were made

>in the late seventies when interest rates and inflation were

>at nauseating levels and many companies tried many different

>things to save money. So who knows?

>

>I have a friend who bought a house that was built in 1978 and

>when he went to replace the soffits and face boards on the

>roof edges because they were falling apart, he found that they

>were made of compressed cardboard!

>

>Doug

Doug:

I scraped and scraped and sure enough, a faint copper color began to appear in the original Advent wires. They are indeed made of tinned copper.

I apologize for my mistake.

One-Shot Scot

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Guest One-Shot Scot

<>

1 Non-inductive resistor, 1 ohm.

1 Non-inductive resistor, 1.5 ohm.

1 Capacitor, non-polarized 13uF

1 Three-position tweeter switch

4 Speaker connectors, which appear to be 20-gauge aluminum wire.

1 Inductor, specifications presently unknown. (I would appreciate hearing from anyone who knows the inductance value and DCR (ohms) rating of the original New Advent inductor.)>>

*** *** ***

My DMM + LCR Meter arrived last Thursday and I was able to obtain the inductance value of the New Advent.

I checked 8 inductors from a mix of A3/A4/U4 crossovers and got the following values:

0.316 Mh

0.334 Mh

0.337 Mh

0.299 Mh

0.337 Mh

0.329 Mh

0.319 Mh

0.327 Mh

2.598 Mh Total ÷ 8 = 0.325 Mh

The average inductance was 0.33 Mh.

The average DCR was 0.55 ohms.

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