Hi, I wanted to upgrade the crossovers of a Wharfedale Linton 85th. I was trying to find out what the signal path is before reaching the driver so I found a schematic online and various images. Looking at the schematic it looks like after the signal reaches the tweeter, it goes through R2, C3 and then through L1 for the second time before go back to the circuit's minus. This seems a bit odd and I was wondering if the polarity of the drivers could be displayed incorrectly here. Why would there be components after the drivers? Can someone explain?
Here is an image of the path on the crossover board.
Here is an image of the path on the crossover board.
Thanks for the replies. I still don't fully understand the schematic. Current flows from the circuit's plus to minus so there still is an order in which current passes through the components, including the parallel components, right? If so what is that order? Correct me if I'm wrong. And why are the tweeter and mid driver's plus and minus reversed compared to the bass driver?
Regarding the change. I want to play around with the internals and improve the sound. The designer stated that audible improvement is possible, especially with the coils and resistors. The caps are mostly pp already but I've seen people swap it for mundorf or jantzen so I'm curious about that aswell.
Regarding the change. I want to play around with the internals and improve the sound. The designer stated that audible improvement is possible, especially with the coils and resistors. The caps are mostly pp already but I've seen people swap it for mundorf or jantzen so I'm curious about that aswell.
The plus and minus symbols on the driver terminals simply indicate the phasing. If a 1.5 V battery were connected across the terminals in that polarity, the driver cone would move outward.
The electrical out of phase connection of the mid and hi drivers in this crossover is necessary to ensure they are acoustically in phase with the woofer.
I suggest you start off by analysing a simpler crossover circuit - such as the one attached.
The Linton 85's crossover contains additional response shaping components in addition to the essential crossover components, making it difficult to analyse.
Attachments
That makes me wonder what audible improvement you are looking for.
It would be interesting to know what your source of dissatisfaction is with these fine speakers.
Note that air core coils having the same low DC resistance as the fitted iron core coils would be very large and very expensive, and you may struggle to hear an audible improvement (reduction in distortion) at normal listening levels.
I am of the camp that says that ceramic resistors 'sound' just fine - any small inductance they have is only likely to have an effect at frequencies above the audible range.
It flows both ways.
It passes simultaneously.
..and less current means more Voltage.
Thanks! Now the schematic makes sense.
This one I can understand. I'll try and put the Lintons in Xsim to get a sense of what some of it does.
Not dissatisfied nor a certain expectation. I know the opinions vary on the effect of component upgrades. Some have (very) very strong opinions. I want to see for myself and learn something about crossovers. Nobody will die if my resistors are overspec'd
This one is hard to grasp. The components are in a certain order and the output is different if that order was different, no?
This one from Peter Comeau? He states that some benefit is possible.
"I thought would put my official reply into this thread because there’s a lot of misinformation out there and it is worrying owners who, otherwise, would probably be quite happy with their speakers. I don’t want to get into arguments with people who have strong opinions on this subject, but you all deserve to know the difference between fact and BS. So here goes …
Resistors: as is typical in the hi-fi manufacturing industry, we use Cermet resistors. These are wirewound resistors encased in a ceramic housing. Generally they do their job very well and have minimal effect on dynamics. You can replace them with Mundorf Supreme and possibly get some benefit. I suspect that is probably the biggest audible difference in the HEADquarter Audio mod.
Capacitors: the majority of caps in the standard crossover are polypropylene. There are some high value electrolytics but they are bypassed with PP caps to reduce any distortion. So is there any reason to replace them? You could replace the electrolytics with a load of PP types but you’ll have trouble fitting them on the PCB.
I don’t really understand why HEADquarter Audio think that the really superb quality PP cap in the HF section can be improved by a Jantzen type? But I will get hold of some Jantzen caps and do some tests and report back on what I hear, probably after Christmas.
Coils: we use silicon iron layered core inductors in the bass and midrange in order to keep DC resistance low. These types of cores have a good hysteresis loop and, in general, I prefer to keep DC resistance low especially for high value inductors in the bass. There would be an audible difference if you replace the midrange coil with an air core but make sure you keep the DC resistance low. Which means a big coil! So you need to Mount it off the PCB and keep it well away and at right angles to the other coils.
What is often not appreciated about air core coils is that they are much more prone to electromagnetic interference than cored coils. So, if you’re going to use them, you need to space them well apart. Usually I use two PCBs if I’m going to do this.
Terminals: all our terminals are plated copper. Why people want to replace terminals like these I don’t understand. There might be a benefit in using a low metal content terminal like the special ones from WBT. Keeping the metal content low is supposed to reduce eddy current effects. But then you have all the wires and coils inside the speaker, which also contribute these effects, so what are you going to do?
Cables: we use good quality connecting cables internally. Some people like exotic cables. You could play around here but IMO the benefits, if any, are minimal. But maybe worth it to some people.
Solder connections to drive units: The reason we use push on connectors is to enable easy servicing. I have seen lots of drive units ruined by overheating the terminals when poorly soldered by hasty service mechanics. Years ago I held a blind listening test on soldered vs push on terminals. The results were inconclusive. Here’s why I think that is …
We crimp push on terminals onto the cables using high pressure machines. This makes an excellent metal to metal, air free joint. The push on terminals then slide tightly onto the drive unit terminal blades. This wiping action again makes a good metal to metal contact and our terminals are the locking type which means that contact stays stable. With soldered joints the current passes from the cable through solder to the blade. Most solder is an amalgam of different metals which lower its melting point, has a chemical action on the metal to wet it, and is oxidised when it melts and cools. If you’re going to use solder make sure it has a high percentage of silver and solder at the manufacturer’s recommended temperature.
Frequency response: Frequency response in axis at 1m doesn’t give you any clue as to how a speaker sounds. The ear/brain system is much more critical of temporal performance and whether the harmonic structure of an impulse is correct/realistic than it is of 3dB changes in frequency level. Also, how you make these measurements is critical. Making a gated response in-room, like GR Research, is prone to huge errors. Compare its results to the Stereophile and Erin’s Audio Corner reviews. Erin and Stereophile accord to the measurements I make as a designer.
Nuff said."
You seem to be trying to say yes or no to each component based on what you see. I would suggest there's more to it than appearance.
You are experimenting.. and that's OK. So do all components make a difference? Maybe none do? Why are you attempting to determine if only half of them do, without any evidence? If someone were identifying the operating conditions and parameters responsible for changes in sound, then I'd expect them to seek them out via measurement or similar analysis.
Crossover upgrades ordinarily involve determining the component values, the circuit itself. If that's good, then why not get yourself some EQ for the speaker overall, and find a good location for it.
I am curious: when substituting the electrolytics that are being bypassed with PP, wouldn't it be a wise choice substituting a pair for an equivalent one since they are in parallel?
For example the woofer has two: 68uF and 18uF. Could we put a 82uF standard value instead and get better performance with less components? It's only 4uF less.
The midrange has 22uF and 8.2uF. Could we put a standard value 33uF in spite of a 3uF difference?
Or is it better to substitute for same values one to one?
I am guessing that both the 8.2uF and 18uF are polypropylene.
Hi wyup!
Those 'strange' parallel combinations of capacitance in this carefully designed crossover have been arrived at through careful analysis of the response of the speaker.
Your substitutions would change those values by 5% and 10% respectively, enough to change the response from that which the designer intended.
Rest assured that Peter Comeau knows what he is doing!
P.S. Looking at the photo of the crossover board in post #1, both the 8.2 uF and 18 uF are yellow film capacitors.
The 22 uF and 68 uF they are in parallel with respectively are electrolytics because equivalent film types would be large and expensive.
Those 'strange' parallel combinations of capacitance in this carefully designed crossover have been arrived at through careful analysis of the response of the speaker.
Your substitutions would change those values by 5% and 10% respectively, enough to change the response from that which the designer intended.
Rest assured that Peter Comeau knows what he is doing!
P.S. Looking at the photo of the crossover board in post #1, both the 8.2 uF and 18 uF are yellow film capacitors.
The 22 uF and 68 uF they are in parallel with respectively are electrolytics because equivalent film types would be large and expensive.
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