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TrueBluePhil

Crossover Cap Value

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I have 4 Large Advents form 1978 and I just reformed them and rebuilt the crossovers. After this the mid ranges and upper ranges really should harsh. I think it could be the caps that I replaced. The originals were 13uF and I replaced them with 16uF because it is all I could find that was closest to the original value.

Do you the 16uF caps are causing this harshness or could it be something else.

I am driving the speakers with a Hafler 9300 Transnova Amplifier

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With the higher value caps you are crossing over at a lower frequency, thus putting a strain on the tweeter = more distortion.

12 uF and 1 uF caps are quite common. You can parallel them to get the original 13 uF value which, I assume you had in your new, large Advents.

Erse sells 13 uF caps but they have a minimum order level you may not like. The 12 and 1 paralleled will work just fine.

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Thanks Carl, Thats what I thought but wasn't sure before I change them out. I go the 16uF's from Parts Express. I will see if they have some so I can match it closer to the original specs. Anyone else have some input to this issue. Like where to find good caps?

Phil

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Don't replace the inductor. It's just a copper wire.

Of course Carl is correct--these don't usually go bad. OTOH, Pete has recommended some better inductors for the OLA (yours are the NLA but there may be something to be learned from the OLA discussion).

Here is Pete's Advent page: http://baselaudiolab.com/ADVENT_LA_XO.html

And here is a rather long thread addressing Advent crossovers: http://www.classicspeakerpages.net/IP.Board/index.php?showtopic=6623&st=0

There are parts lists and photos of my xo rebuild, using Erse inductors. Again--this is for the Original, not the New. Maybe Pete will have advice regarding the New.

Another suggestion, as long as you're in there: Try adding some cabinet bracing.

After all that I sold the Advents. Spent too much on the crossovers for something that eventually got sold (at a loss :wacko: )

How much did the Advents improve with the new xo? I'm not sure. They're nice but I prefered the sound of the AR2ax.

Hope this helps.

Kent

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Thanks Jkent. I just got my new Dayton Caps today and will replace them this weekend. I will read Pete's thread on this.

Phil

Of course Carl is correct--these don't usually go bad. OTOH, Pete has recommended some better inductors for the OLA (yours are the NLA but there may be something to be learned from the OLA discussion).
Here is Pete's Advent page: http://baselaudiolab.com/ADVENT_LA_XO.html
And here is a rather long thread addressing Advent crossovers: http://www.classicspeakerpages.net/IP.Board/index.php?showtopic=6623&st=0
There are parts lists and photos of my xo rebuild, using Erse inductors. Again--this is for the Original, not the New. Maybe Pete will have advice regarding the New.
Another suggestion, as long as you're in there: Try adding some cabinet bracing.
After all that I sold the Advents. Spent too much on the crossovers for something that eventually got sold (at a loss :wacko: )
How much did the Advents improve with the new xo? I'm not sure. They're nice but I prefered the sound of the AR2ax.
Hope this helps.
Kent

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ok so i replaced the caps with a 10 uf + 3 uf to get the 13 uf. The Advents still sound very harsh in the mid high and highs. I have installed Pete's BCS box and it has helped smooth things out but I still can hear the harshness although less. Any suggestions on what to do from here?

Phil

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Most modern recordings have gross compression and clipping that a high end

system will not hide if it is accurate. This is no joke, it is a very serious and

pervasive problem:

It has been going on for nearly as long as there have been recordings:

Where do you have the tweeter controls set?

Tell us what specific recordings sound harsh.

Do any sound particularly good?

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Are you sure you used the correct surrounds? Generic surrounds are not as good as this: http://www.ebay.com/itm/LARGE-Advent-10-Classic-Speaker-Deep-Roll-reFoam-Two-woofer-Kit-/261106324302?pt=US_Amplifier_Parts_Components&hash=item3ccb26534e or this: http://www.ebay.com/itm/LARGE-Advent-10-Classic-Speaker-reFoam-Two-woofer-Kit-/260624893108?pt=US_Amplifier_Parts_Components&hash=item3cae7444b4

Also, it is generally believed new foam surrounds have to break in. Play them for hours at low levels, gradually increasing to higher levels. See how they sound after a few days.

Kent

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ok let me answer the questions first.

Are you sure you used the correct surrounds? I have four NLA and two were professionally refoamed 5 years ago. The the other two were done in January this year by me and I used the Msound product so I don't think this is the issue.

Phil, have you verified that the amplifier is good? Well i thought this could be the issue so I changed out my Hafler 9300 and replaced it with another Hafler P-1500 and no change. Ok, then I replaced it with a P-500 workhorse and no difference.

Where do you have the tweeter controls set? Pete, I assume your are talking about the actual controls on the speakers. I usually run them at the normal position but now I have it at the decreased position. My pre-amp has only one bass and one treble. Before I did the XO I ran them in flat position (12 o'clock high) but now I need to have the treble at the 9 o'clock position to make it even bearable.

As to what music recordings it does it on it doesn't matter. I listen to all kinds of music but mostly Jazz, blues and rock and also some classical. Country music isn't worth listening to ;)

So I am at a loss right now. Could it be my pre-amp? I don't have another one to try that.

Phil

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Were the dust caps on the woofers replaced one either pair?

You can try adding 1 ohm in series with the new caps to simulate the

higher ESR of the electrolytic caps, normally I'd suggest .5 ohms but

the NLA tend to be quite hot and 1 ohm will not hurt.

Does the switch seem to make a difference, you might have wired the

XO wrong ....?

Your preamp could need recapping but you seem to be saying that the

change happened after recapping the speakers so it doesn't really

make sense.

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Hi Pete, Yes the dust caps were replaced on all of them. So this could effect them but these were done a while back before the harshness I am hearing now. When I replaced the caps to the 13uF i down loaded the schematic from your site and made sure I had the XO correctly and when I change the switch it makes a slight difference but the harshness is still there. I will try the 1 ohm resister and see if that helps.

As to the pre-amp it is getting old and you would think that it would get muddier instead of brighter/harshness but it could. I talked to John at Musical Concepts and he said that that some propolene caps can take time to break in and it could be that. I think it is a long shot but who knows.

I do know this that todays recordings are shit compared to 70's and 80's. Pete you are correct that there is to much compression and clipping

Phil

Were the dust caps on the woofers replaced one either pair?

You can try adding 1 ohm in series with the new caps to simulate the

higher ESR of the electrolytic caps, normally I'd suggest .5 ohms but

the NLA tend to be quite hot and 1 ohm will not hurt.

Does the switch seem to make a difference, you might have wired the

XO wrong ....?

Your preamp could need recapping but you seem to be saying that the

change happened after recapping the speakers so it doesn't really

make sense.

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Ok, I completely removed my pre-amp and went straight to my amp and the harshness is still there. So I reduced the 8k and 16k frequencies by 8 to 10 db and it smooths out. So it has to be the crossover circuit. What do you think?

Phil

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First, do you find that you have to run the volume control much higher with

the BSC circuit? This is normal and not to worry about but if you do not

then it is in backwards.

I cannot imagine anyway for caps to make an 8 to 10 dB difference. I actually

compared old NPE caps to new films and it was impossible to hear any

difference without using an A/B comparison and even then, it was very

difficult.

Can you go back to your old caps as a sanity check?

The BSC also provides some HF boost but it is very hard to hear if you are

older. It is about 6 dB max at 20 K or above and about 2 dB at 10K. You

can open the BSC box and remove jumpers that disable the HF boost. They

are computer board style slip on jumpers.

In my testing Advents with BSC were very hard to tell apart from a pair of

modern full range monitors that I have here. It was hard to believe and everyone

who A/B compared the two speakers agreed.

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I forgot to mention that I took out the BSC circuit when I did the last test. But when I had it between my pre-amp and amp I did have to increase the volume to get the same levels but it did smooth the sound. It did improve the sound a lot but I could still hear the harness although a lot less.

As to changing the setting on the BSC I would never hear the 20k, but I can at the 10k. I have my hearing checked every year and 14k and up it really drops off. Aging is not good on the ears.

I wish i had kept the old caps but I didn't. Didn't think I would have this issue.

I have another set of NLA woofer sitting waiting to get reformed but the dust caps on them are in good shape so all I am going to change is the foam then install them in two of the speakers then I will do a A/B tests to see if I can tell the difference between them and the ones that has the dust caps changed also. I will be surprised if it does improve the sound though. But if it does then this will be an easy fix.

First, do you find that you have to run the volume control much higher with

the BSC circuit? This is normal and not to worry about but if you do not

then it is in backwards.

I cannot imagine anyway for caps to make an 8 to 10 dB difference. I actually

compared old NPE caps to new films and it was impossible to hear any

difference without using an A/B comparison and even then, it was very

difficult.

Can you go back to your old caps as a sanity check?

The BSC also provides some HF boost but it is very hard to hear if you are

older. It is about 6 dB max at 20 K or above and about 2 dB at 10K. You

can open the BSC box and remove jumpers that disable the HF boost. They

are computer board style slip on jumpers.

In my testing Advents with BSC were very hard to tell apart from a pair of

modern full range monitors that I have here. It was hard to believe and everyone

who A/B compared the two speakers agreed.

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Just to update everyone that has given me great suggestions and I just went back into the boxes to confirm that I did the XO's correctly. I also took the time to replace to old square foam in them and replace them with the OC fiberglass insulation that Carl suggestion doing and WOW! what a difference this makes. The bottom end is back and mids are much smoother. I am beginning to believe that I might have put in the original foams squares in incorrectly and this contributed to the problem.

My next step is to replace all my speaker wires. I have had them on them since the beginning of time and they are beginning to get hard. Does anyone have any suggestion as to what speaker wires and banana plugs to get?

Thats to everyone that has helped me.

Phil

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I have used 16ga and 14ga wire bought off a roll for about $.65 ft. at Home Depot for years. Most of the banana plugs I use are the type where two plugs are molded into one housing. I also have the singles. I personally like the ones where you put the wire through a hole and tighten a screw down on it. There are others that attach the wire internally and they work but 14 ga wire is hard to work with in these. Don't waste your money on expensive wires......you don't need them. Spend your money on the music!

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Well after much frustration I decided to change the caps and resistors again. I replaced them with 13uF SonicCap GEN I Capacitors and Mills Resistors on two of my NLA and my speakers are back to playing smoothly with the detail I have had for 30 years. Man was this an expensive journey but it was worth it.

What I learned from this was that not all caps and resistors that claim to be audio grade works well with all speakers. I am sure that the Dayton Caps and Resistors are good but they didn't do well with my speakers. Tonight I will replace the other two speakers to get to match.

Thanks to everyone that helped me get through this.

phil

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I will, once again, opine that this modern-day replacement of capacitors with types other than those originally installed, without consideration of the effect on the sound of the speaker system and just accepting the general, "these caps will make a HUGE difference" is asking for possible disappointment.

Kloss and his people (and other speaker designers) designed the sound of his speakers around the capacitors available for a reasonable cost at the time (not necessarily the best, admittedly) and just willy-nilly replacing them with other types just because they may be considered "audiophile" is not the best action, in my opinion.

This is not really directed at you, Phil. It's just that your experience seems to verify my opinion.

Doug

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Hi Doug,

For us that aren't engineers what other recourse do we have other then buying audiophile grade parts. I agree what you are saying but we don't have $10,000 of test equipment laying around to test things so we rely on what manufactures and other people say. We have no choice other then buying, trying and then replacing if they don't work as good. Any suggestions?

Phil

I will, once again, opine that this modern-day replacement of capacitors with types other than those originally installed, without consideration of the effect on the sound of the speaker system and just accepting the general, "these caps will make a HUGE difference" is asking for possible disappointment.

Kloss and his people (and other speaker designers) designed the sound of his speakers around the capactors available for a reasonable cost at the time (not necessarily the best, admittedly) and just willy-nilly replacing them with other types just because they may be considered "audiophile" is not the best action, in my opinion.

This is not really directed at you, Phil. It's just that your experience seems to verify my opinion.

Doug

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