Kef 304 vs Advent Prodigy

[Rmdav8]

Hello,

Looking to get some opinions on the kef 304 (export versions of the Concord III) since I have not heard one and there is a set on CL near me for $160 w stands but tweeters might be blown.

I currently have a set of advents prodigies that I reformed so I was hoping to get ppls opinion on if I should stick with the advents or move to the kefs.

This is my first post, so my apologies if this post is unorthodox or not welcome here.

 

[WillMeyer]

I know nothing about the KEFs, but I know alot about the Prodigies. I've done a couple of minor inexpensive upgrades that take that speakers to a whole new level.

The KEFs have a great reputation and I'm sure you won't go wrong with them. But if you decide to invest a little bit of money in the Prodigies, they will really impress you.

I have 2 pair, so I would try something on one pair, do A/B testing against the other pair , and if sucessful, upgrade the second pair. The Jensen era Advents have great drivers and a nice cabinet, but their crossovers are as cheap as they come. Also Advent put minimum sound isulation inside the cabinet. For around $40 to $50 you can fix the issues by: 1) Adding additional sound insulation 2) Replace the 2 electrolytic capacitors with Metalized Polypropylene (if I remember correctly without checking my notes it uses a 6uF and a 13uF). - this is in the tweeter circuit and it will significantly improve the high end, and 3) change the 2 inductors (300uH and 200uH) to larger iron core or preferably air core inductors.
If you are interested in pursing the upgrade direction, reach out to me and I'll send you pictures and info. I'd be willing to walk you through it. I have a post on this site with a picture of the upgraded crossover. See Crossover-Inductor Question

 

[philster]

I know nothing about the KEFs, but I know alot about the Prodigies. I've done a couple of minor inexpensive upgrades that take that speakers to a whole new level.

The KEFs have a great reputation and I'm sure you won't go wrong with them. But if you decide to invest a little bit of money in the Prodigies, they will really impress you.

I have 2 pair, so I would try something on one pair, do A/B testing against the other pair , and if sucessful, upgrade the second pair. The Jensen era Advents have great drivers and a nice cabinet, but their crossovers are as cheap as they come. Also Advent put minimum sound isulation inside the cabinet. For around $40 to $50 you can fix the issues by: 1) Adding additional sound insulation 2) Replace the 2 electrolytic capacitors with Metalized Polypropylene (if I remember correctly without checking my notes it uses a 6uF and a 13uF). - this is in the tweeter circuit and it will significantly improve the high end, and 3) change the 2 inductors (300uH and 200uH) to larger iron core or preferably air core inductors.
If you are interested in pursing the upgrade direction, reach out to me and I'll send you pictures and info. I'd be willing to walk you through it. I have a post on this site with a picture of the upgraded crossover. See Crossover-Inductor Question

Do you think the crossover upgrade would translate to the advent maestro as well??

 

[WillMeyer]

I never owned a set of Maestros, but I've owned most of the other sets of Jensen era Advent ( I am looking to buy a set of Maestros though). When I saw your posting I went to the internet to research the Maestro crossover. Its typical Advent (picture attached) except it does include a large air core inductor.

Assuming the picture and downloaded schematic are correct (you can compare it to yours), I would do the following if they were my speakers.
1 - Add additional sound insulation. Don't go overboard- you can overstuff the cabinet which I found muddies the sound - but make sure there is a layer of sound insullation on the top, bottom, back wall, and side walls.
2 - change to poly caps - there are only 2 so it won't be expensive.
3 - I would keep the large air core inductor but would consider upgrading the smaller iron core inductor although this would probably not yeild much of an improvement.
4 - the terminal package that the crossover is attached to... Its the same size as the ones used on the Advent Heritage even with the same tweeter fuse. I've bought them on eBay pretty cheap and used them on my Laureates and Prodigies (I have to open up the cabinet with my sabre saw for the Prodigies-but they fit right in on the Laureates). The advantage to the Heritage is they have 5 way binding posts and take banana plugs.

 

[Lou G]

I have never heard the KEF 304 but I have been a KEF fan since 1979, when I purchased my first KEF speakers. The KEF 304s have the well regarded T33 soft dome tweeter and two B200 (8 inch) midrange drivers. It was one of the first 2 1/2 way designs. The response of the lower B200 driver is progressively reduced as the frequency rises so that only the upper driver is radiating in the crossover region. Thus it is possible to retain the advantage of twin drivers at the low end of the range without the phase interference effects usually associated with multiple drive units. The KEF 304s were sold between 1979 and 1980. Most KEF speakers made around this period had a very smooth, rich somewhat laid back presentation. They are typically easy to listen to for long periods without any ear fatigue.

If the T33s are blown, there are replacements available on the bay but that may be more than you want to get into. If they are blown the selling price should be much less than $160.

 

[philster]

I never owned a set of Maestros, but I've owned most of the other sets of Jensen era Advent ( I am looking to buy a set of Maestros though). When I saw your posting I went to the internet to research the Maestro crossover. Its typical Advent (picture attached) except it does include a large air core inductor.

Assuming the picture and downloaded schematic are correct (you can compare it to yours), I would do the following if they were my speakers.
1 - Add additional sound insulation. Don't go overboard- you can overstuff the cabinet which I found muddies the sound - but make sure there is a layer of sound insullation on the top, bottom, back wall, and side walls.
2 - change to poly caps - there are only 2 so it won't be expensive.
3 - I would keep the large air core inductor but would consider upgrading the smaller iron core inductor although this would probably not yeild much of an improvement.
4 - the terminal package that the crossover is attached to... Its the same size as the ones used on the Advent Heritage even with the same tweeter fuse. I've bought them on eBay pretty cheap and used them on my Laureates and Prodigies (I have to open up the cabinet with my sabre saw for the Prodigies-but they fit right in on the Laureates). The advantage to the Heritage is they have 5 way binding posts and take banana plugs.

Yah I think I’ll leave the inductors alone and change the 4uf and 14uf caps. I’ll look for the binding posts u mentioned. What kind of stuffing?? The pillow stuff you can get at Walmart. Also the maestros have a foam material on the front of the cabinet but mine has been pulled off. You can buy the foam at PE and there is a good read and pics on a maestro restore in the tech talk section

 

[WillMeyer]

The walmart stuffing in blanet form works great (polyfill). I use fiberglass insulation on my air suspension speakers and found that easy to work with and effective. That stuff makes me itch so I only use it in sealed enclosures

Parts Express is a good source for the caps. If you need any help send me a message. My recommendation is to go with basic poly caps. I like Solens but Daytons and Audyns are fine. You'll find that the cheapest poly cap sounds better than the best electrolytic caps.

I took a quick look at PE, and you can get a Dayton 4uF for $2, and while a 14uF isn't available, you can get a 12uF for $4.50 and put a 2uF (@ $1.60) in parallel with the 12 to get your 14uF. Total cost for the upgrade $8.10 per speaker. Nice inexpensive upgrade and a good learning exercise.

Be aware the poly caps are alot larger than the electrolytic caps so you may have to be creative in your mounting. I've attached a couple of pics for your reference. One is of an Infinity crossover so you can see one example of mounting these and an idea of their size. The other pic shows a standard (but blown) Prodigy crossover, in the back you will see a Prodigy crossover with upgraded caps and inductors. In particular notice that the large cap has a small cap piggy-backed. As I suggested above, to get the value you need, you sometimes have to wire 2 caps in parallel.

I hope this helps.

Enjoy the music!