@chrisng you’re a machine! 🙂 thank you muchly. ❤️
Right - I’ll get the inductor measurements from the K and the last inductor measurement from the K2 and annotate the circuits kindly provided by Chris and post back here. Gimme a couple of days.
Also, I wasn’t expecting the bass to have no filters. Looks like my tracing skills are rubbish 😂
Right - I’ll get the inductor measurements from the K and the last inductor measurement from the K2 and annotate the circuits kindly provided by Chris and post back here. Gimme a couple of days.
Also, I wasn’t expecting the bass to have no filters. Looks like my tracing skills are rubbish 😂
It took me a while to figured out where the 1.47mH coil connected to until I saw the photo on post #17. 🤔
Hi there,
I read earlier that the cross-over frequencies were meant to be 1.5Khz & 6Khz. (I am assuming the drivers are 8 ohms)
I was looking at the component values in the circuit just above, and some things just don't add-up.
I will start with the tweeter and work down to mid and then bass.
With a (Tw.) capacitor of 5uF, the corresponding (mystery coil) should be .5mH giving a XO. of 2.5Khz. (that is not 6Khz)
In fact there are no 6Khz filters using 5uF without severe impedance implications.
Now, the Mid 'hi-pass' using 10uF & 1.47mH = a XO. of 1.1Khz. (not 1.5Khz)
The Mid 'low-pass' using .32mH & 5uF is problematic, giving a XO. of around 3.5Khz but with an output peak and
corresponding impedance dip. (certainly not 6Khz)
With the woofer having no filtering, I don't really see it rolling off naturally at 1.1Khz, surely it would go higher.
I would love to know more about the drivers and see a picture.
I read earlier that the cross-over frequencies were meant to be 1.5Khz & 6Khz. (I am assuming the drivers are 8 ohms)
I was looking at the component values in the circuit just above, and some things just don't add-up.
I will start with the tweeter and work down to mid and then bass.
With a (Tw.) capacitor of 5uF, the corresponding (mystery coil) should be .5mH giving a XO. of 2.5Khz. (that is not 6Khz)
In fact there are no 6Khz filters using 5uF without severe impedance implications.
Now, the Mid 'hi-pass' using 10uF & 1.47mH = a XO. of 1.1Khz. (not 1.5Khz)
The Mid 'low-pass' using .32mH & 5uF is problematic, giving a XO. of around 3.5Khz but with an output peak and
corresponding impedance dip. (certainly not 6Khz)
With the woofer having no filtering, I don't really see it rolling off naturally at 1.1Khz, surely it would go higher.
I would love to know more about the drivers and see a picture.
@Mister Audio I’ll need to apologise I think as I may have created some confusion. The original reason for this thread was the magnum K (not K2) crossover. But since @chrisng traced it with ease, I asked him to look over my K2 pic as well. So we’ve unintentionally got 2 different speakers in the mix here. The crossover frequencies posted by @Galu of 1500 and 6000 in this link: https://worldradiohistory.com/hd2/I...ecording-IDX/IDX/ATR-1966-4-OCR-Page-0025.pdf are for the K not the K2.
I’d have to look into the K2 frequencies when I get back from the school run, I will also have some time today to measure the inductors on the K. I’ll repost the crossover pics with additional annotations.
I’d have to look into the K2 frequencies when I get back from the school run, I will also have some time today to measure the inductors on the K. I’ll repost the crossover pics with additional annotations.
I just did some YouTube watching - I must say these are old & rare speakers.
If the bass & mid drivers are not damaged, I would say they are worth 'treasuring'.
With the K's (not K2's) I saw 2 coils and 3 capacitors.
Just to be sure, do the speakers you want to work on have > cone, or dome tweeters?
Are they the K's or K2's ?
If the bass & mid drivers are not damaged, I would say they are worth 'treasuring'.
With the K's (not K2's) I saw 2 coils and 3 capacitors.
Just to be sure, do the speakers you want to work on have > cone, or dome tweeters?
Are they the K's or K2's ?
@Mister Audio yes the Ks are rare. I have 2 pairs of Ks and three pairs of K2s... given free of charge a couple of weeks ago. Some sort of house clearance.
The Ks have an inferior cone tweeter, superior alnico mids, and the bass goes down to 20,000Hz on paper IIRC. The K2s have the superior DT-3 dome tweeter but the inferior midrange driver and the bass goes down to 22,000Hz on paper.
I am currently considering modding a pair of Ks and K2s but I want to have a 'factory spec' pair to compare. For this reason, I am rebuilding the crossover with newer components and fresh ofc wire to make them as good as possible for the comparison.
One thing I had considered, was having a pair of the Ks with a pair of the DT-3s in.. I'm still brainstorming at the moment.
Here is the annotated K crossover:
The Ks have an inferior cone tweeter, superior alnico mids, and the bass goes down to 20,000Hz on paper IIRC. The K2s have the superior DT-3 dome tweeter but the inferior midrange driver and the bass goes down to 22,000Hz on paper.
I am currently considering modding a pair of Ks and K2s but I want to have a 'factory spec' pair to compare. For this reason, I am rebuilding the crossover with newer components and fresh ofc wire to make them as good as possible for the comparison.
One thing I had considered, was having a pair of the Ks with a pair of the DT-3s in.. I'm still brainstorming at the moment.
Here is the annotated K crossover:
Attachments
Well, one is done! 🙂
I developed new levels of hate for these Goodmans crossovers removing those Lpads and don’t get me started on the bolt securing the cap clamp. Everything was glued and lacquered. The mind boggles how they can put effort to secure those sorts of things, then use the crappiest wire in the world for the drivers. 🤷♂️
I developed new levels of hate for these Goodmans crossovers removing those Lpads and don’t get me started on the bolt securing the cap clamp. Everything was glued and lacquered. The mind boggles how they can put effort to secure those sorts of things, then use the crappiest wire in the world for the drivers. 🤷♂️
Attachments
@chrisng Looks like a mod has done that for me 😉 I'll open a K2 and get the tweeter inductor value and post back over the next couple of days then both are complete 🙂
@Mister Audio the value in there at the moment is 4.7uF, I have some 3.3s somewhere. You're absolutely right, the K tweeter is naff. On paper, really it's just the alnico mid that the K has going for it. I wonder what a combination of K2 bass/tweet and K mid would sound like? 🤔
Thank you very much to everyone who has helped with this 👍
@Mister Audio the value in there at the moment is 4.7uF, I have some 3.3s somewhere. You're absolutely right, the K tweeter is naff. On paper, really it's just the alnico mid that the K has going for it. I wonder what a combination of K2 bass/tweet and K mid would sound like? 🤔
Thank you very much to everyone who has helped with this 👍
Just found some DT-2s in box.... are these not practically identical to the DT-3s except minor QC improvements?
I forgot to mention a few things >
The XO. frequencies of the 'correct' K circuit are: 1.2Khz and 5Khz, depending slightly on the impedance of the drivers.
2 times 2.2uF caps in parallel will give you 4.4uF. That would probably be better than 3.3uF.
With such old drivers, if you ever remove the woofers from the box, take the opportunity to treat the 'flexible chassis to cone wires'
by gently coating them with motor oil (WD40 is too thin). This will prevent likely future failure due to corrosion.
You could even go as far as securing a large "silica gel pack" in the box.
Happy fun fun 🙂