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bennybee

Advent Heritage Xover upgrade produces too much treble

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Hi List,
I am very glad to have found this forum. Iam an Advent fan since I heard the Large Advent and the Powered Advents about 20-25 years ago. They were beyond my budget then, so my first pair of Advents were the 5004 (I think that's what they were), but about 15 years ago I bought the Heritage pair that I'm still enjoying today. Reading a thread here by 'jmitchnh' a few weeks ago, I decided to upgrade the crossover filters like he did. The original capacitors were the KSC electrolytics of resp. 20MFD and 6MFD (+/-10 p.c.) 100V. I replaced these by black Jantzen Crosscaps of 22uF and 6.2uF (+/-10p.c.) 400V.
I could not find the exact same values but figured that these were within acceptable limits. The original KSC 1ohm resistor was also replaced by a Jantzen MOX 1ohm 10W resistor.
I installed the components last saturday and was at first very enthusiastic. I 'upgraded' one speaker and compared L/R with the old one : there was a bit more and somewhat tighter bass, a more open and brighter sound, clearer voices (less 'boxy'). Persuaded that there was an improvement I then also tackeled the second speaker. After a couple of hours though, I began to notice that there was way too much treble, to a point that it becomes annoying and even painful to the ears with f. ex. guitar solos (Santana on 'Europa') or high pitched voices (Temptations' ooh-ooh-ooh crying high falsettos). I need to turn down the volume and the treble control of my Sony amp TA-FA50ES. Will this improve after a burn-in time of the caps? I must say that until now I din't believe in the voodoo of burning in cables and capacitors with pink noise or hundreds of hours of music or what-have-you, but given the slight disappointment in my 'upgrade' I'm now silently hoping that burning in caps will have an effect...! Could the small difference in value of the capacitors be the reason that too much energy goes to the Advent's tweeter? Or is this the character of these particular capacitors and should I try another brand of caps? Can I perhaps add a resistor somewhere to reduce the energy sent to the tweeter? Thanks in advance for your advice and for sharing you experiences.
kr, Bennybee

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Here are the complete crossover component values for the Advent Heritage (Classic Heritage, twin woofer). I originally only replaced the caps, but then discovered at higher volumes, the iron core inductors were saturating. I replaced the woofer inductors with Erse iron core inductors and the saturation issue was resolved.

I also replaced the tweeter inductor with an air core type.

I used DATS 2 to make the measurements.

Advent Heritage Crossover Values_062618.pdf

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@THD+N   How did you measure the inductor saturation?

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I think this is a good example of users, out in the field, changing things around in a speaker without considering the original design or why certain components are in a speaker. I realize cost is often a major factor in speaker design and construction but, the thing is, the components in a speaker ARE the components in the speaker and if you go changing them, you may well alter the sound but not necessarily for the better.

Doug

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