New Large Advent Model Numbers

[Horswispr]

Does anyone know the differences (if any) between the Advent A3 and A4? Both are New Large Advents with similar woofers and fried egg tweeters. I have one pair of each, and the internal wiring appears to be heavier in the A4. The A4 also has leads to positive on the left, the A3 on the right (to the woofer and the tweeter; the hookups on the backs of the speaker cabinets are the same). I don't Know if these differences are representative. I think these are wonderful sounding speakers, by the way.

Thanks!

[Doug G.]

I have heard of the larger wire thing before but is the actual wire larger or just the insulation?

They must have changed production methods on the woofer somewhere along the line and ran the ends of the coil to opposite positions. Or the coil is wound the opposite from previously and would thus have to hooked up opposite so the cone moves the same direction.

Doug

[Guest One-Shot Scot]

>>"Does anyone know the differences (if any) between the Advent A3 and A4?"

I have noticed differences in cabinet construction of the A3 and A4 models. The A3 appears to have used plywood for the top, bottom and sides of the cabinet, while the A4 seems to have gone to 100% particle board construction as you can see here:

http://home.comcast.net/~scot100/Advent/Ne...ntCabinets.html

>>"Both are New Large Advents with similar woofers and fried egg tweeters. I have one pair of each, and the internal wiring appears to be heavier in the A4."

There are differences in the layout of the A3 and A4 crossovers, but the components are identical. The A4 wiring appears thicker than the A3 wiring, but I feel that this is only because the insulation is thicker on the A4 wires. The gauge of the actual wire seems the same:

http://home.comcast.net/~scot100/Advent/Ne...Crossovers.html

>>"The A4 also has leads to positive on the left, the A3 on the right (to the woofer and the tweeter; the hookups on the backs of the speaker cabinets are the same). I don't Know if these differences are representative. I think these are wonderful sounding speakers, by the way. Thanks!"

I have not noticed any difference in the leads. However, the specifications of the components of the A3 and A4 crossovers are the same:

NEW ADVENT A4, A3 U4 and U3 Crossover Specifications:

(1) 4.75" x 4.75" x 1/8" Masonite board

(1) 3-position tweeter switch

(1) 0.33 mH inductor *

(1) 13uF bi-polar capacitor

(1) 1ohm 10W resistor

(1) 1.5ohm 10W resistor

(2) binding posts

(The wire gauge specifications below are estimates. The original wire is so thin that it may actually be 22 gauge.)

(1) 20 gauge stranded yellow wire

(1) 20 gauge stranded red wire

(2) 20 gauge stranded black wires

(1) 20 gauge solid yellow wire

* There are reports that the New Advent crossover used a 0.300 mH inductor and some crossovers had this value. I have checked a total of 16 New Advent crossovers (a mix of A3, A4, U3 and U4) and found that 10 inductors produced readings between 0.324 and 0.334 mH. Of the other 6 inductors, 4 had values under 0.324 mH and 2 had values over 0.334 mH. (The lowest reading was 0.296 mH and the highest reading was 0.337 mH.) When the values of all 16 inductors is averaged, a median value of 0.323 mH is the result. Therefore, I have concluded that 0.330 mH was the target value.

When rebuilding New Advent crossovers, higher-quality inductors are readily available in both 0.300 and 0.330 mH values. My choice is the 0.330 mH inductor, which is much closer to the median value of 0.323 mH than the 0.300 mH inductor.

I hope this helps.

[Guest MarkG]

>>"Does anyone know the differences (if any) between the Advent A3 and A4?"

There are differences in the layout of the A3 and A4 crossovers, but the components are identical. The A4 wiring appears thicker than the A3 wiring, but I feel that this is only because the insulation is thicker on the A4 wires. The gauge of the actual wire seems the same:

I have not noticed any difference in the leads. However, the specifications of the components of the A3 and A4 crossovers are the same:

I hope this helps.

I just opened up my U3s and they look very similar with the same components. I traced out the crossover schematic and it seems that in the

extended position they short out the inductor to the Woofer. The 8 ohm side of the input is connected to the center contact of one side of the

switch and when in the ext position, it reads shorted to the woofer, effectively shorting out the inductor. Otherwise, I believe it has 13 uF and

1 ohm to the tweeter in normal mode, 13 uF and 2.5 ohms to the tweeter in dec mode and 13 uF and .6 ohms to the tweeter in ext mode.

Do you agree with this? Is it wired correctly? It is hard to tell the connections from your pictures, but it appears to be the same.

Got suggested caps? I was going to go with Solen 10 and 3 in parallel. I'm not a golden ear so I probably can't tell the difference in

inductors, but I can certainly tell the difference between 20+ year old electrolytics and new Metalized PPs.

Thanks for posting this info. It's just what I needed.

Mark

[Guest MarkG]

I saw http://baselaudiolabs.googlepages.com/ADVENT_LA_XO.html and it sure seems like they really did short out the

woofer series inductor. They did not do this in earlier or later large advents. I think I need to replace two inductors.

What did you use?

Mark

[Guest One-Shot Scot]

<<"I just opened up my U3s and they look very similar with the same components. I traced out the crossover schematic and it seems that in the extended position they short out the inductor to the Woofer. The 8 ohm side of the input is connected to the center contact of one side of the switch and when in the ext position, it reads shorted to the woofer, effectively shorting out the inductor. Otherwise, I believe it has 13 uF and 1 ohm to the tweeter in normal mode, 13 uF and 2.5 ohms to the tweeter in dec mode and 13 uF and .6 ohms to the tweeter in ext mode. Do you agree with this? Is it wired correctly? It is hard to tell the connections from your pictures, but it appears to be the same.">>

Sorry that I took so long to reply. I have been away for the holiday.

I do not feel qualified to make comments as to the specifications of the New Advent 3-position tweeter switch. In my opinion, you are better off without it, because it has been subjected to at least 25 years of corrosion. I made two sets of entirely new crossovers and found that using a single Mills 1 ohm 12w non-inductive resistor in the tweeter path provides the best overall sound. This is the equivalent of using the "Normal" setting of the original New Advent tweeter switch.

Unfortunately, the original New Advent crossovers were made of the cheapest components: lightweight inductors, sand-cast resistors, electrolytic capacitors, low grade binding posts and thin-gauge wire. This is a real shame, because the New Advent's high-quality wood cabinets, woofers and tweeters were crippled by the use of such inferior crossover components.

A typical, low cost New Advent crossover upgrade procedure involves replacing the original electrolytic capacitors with metallized polypropylene models and replacing the original sand-cast resistors with the same type or wire-wound models. The midrange and highs will definitely benefit from these upgrades, but the low end sound will still be restricted by the low quality, original New Advent inductor. The original New Advent inductor weighs 2.5 ounces, which is approximately half the weight of even the cheapest 14 to 15 gauge replacement. I feel that upgrading the inductor is an essential part of rebuilding a New Advent crossover.

<<"Got suggested caps? I was going to go with Solen 10 and 3 in parallel. I'm not a golden ear so I probably can't tell the difference in inductors, but I can certainly tell the difference between 20+ year old electrolytics and new Metalized PPs.">>

If you are able to find a poly cap in Advent's original 13uF value, you are doing well. Some say to compromise and use a poly cap with a value of 12uF and others say to use a 12uF in parallel with a 1uF. While the latter combination is better than using the wrong value, I prefer to use capacitors that are of nearly equal value, by combining a 6.2uF with a 6.8uF. While Solen is a good choice, I was unable to decide between using Solen and using Jantzen. (I also considered using Dayton, but its specifications were not as good as those of Solen and Jantzen.) My compromise was to use a Solen 6.2uF in parallel with a Jantzen 6.8uF. I also eliminated the 3-position tweeter switch and used a Mills 1 ohm, 12W resistor to soften the tweeter. (If you use the 3-position tweeter switch, you will need to add a 1.5 ohm resistor to duplicate the 1 ohm (Normal) and 2.5 ohm (Decrease) values of the original crossover.)

Here is my list of parts that I purchased from Parts Express:

255-614 Janzen 0.33mH 16 gauge copper foil inductor (used on one pair of crossovers.)

255-404 Janzen 0.33mH 15 gauge air core inductor (used on another pair of crossovers.)

027-558 Solen 6.2uF-400 VCD polypropylene capacitor

027-928 Jantzen 6.8uF-400 VCD polypropylene capacitor

005-1 Mills 1 ohm 12w non-inductive resistor

091-1247 Dayton binding posts

260-330 Acousta Stuf (used in combination with the original New Advent foam squares.)

These items were also used:

Radio Shack 18 gauge stranded wire

Spade connectors

Solder

Hot glue

<<"Thanks for posting this info. It's just what I needed. Mark">>

Once again, I hope I have been of some help.

One-Shot Scot

[Guest MarkG]

Here is my list of parts that I purchased from Parts Express:

255-614 Janzen 0.33mH 16 gauge copper foil inductor (used on one pair of crossovers.)

255-404 Janzen 0.33mH 15 gauge air core inductor (used on another pair of crossovers.)

027-558 Solen 6.2uF-400 VCD polypropylene capacitor

027-928 Jantzen 6.8uF-400 VCD polypropylene capacitor

005-1 Mills 1 ohm 12w non-inductive resistor

091-1247 Dayton binding posts

260-330 Acousta Stuf (used in combination with the original New Advent foam squares.)

These items were also used:

Radio Shack 18 gauge stranded wire

Spade connectors

Solder

Hot glue

Once again, I hope I have been of some help.

One-Shot Scot

I have mixed old and new Advents so I got 8 uF Solens and 5 uF Solens so I could make up 13 uF or 16 uF. I like the new metal tweeters much better

than the masonite ones. I also got two Solen 16 ga inductors for two of the 4 speakers I rebuilt. I decided to keep 4 with newer woofers and tweeters.

I had lent my speakers to someone a few decades ago and replaced two resistors that they burnt up with nothing special.

I could easily tell the improvement with the caps, not really tell the inductors or resistors. The two speakers I rebuilt more fully I just bypassed

the switch and wired it "normal".

I wound up with newer metal woofers and tweeters in original large Advent cabinets with crossovers that match the new ones (13 uF .33 mH 1 Ohm).

Probably sacrilege to some, but sounds like the other pair of new Advents I rebuilt to me. I'll probably sell the masonite tweeters and woofers I have left

over with the correct crossover parts for those drivers. I'm sure some prefer those. I started out with 7 speaker of various vintages and cabinet sizes

and wound up with two pair stacked large Advents with the new drivers.

Thanks again for your info.

Mark