Line level crossover
HI Pierre,
Tried to simplify a little. Have only made some guesswork about crossover-frequencies.
Tried to simplify a little. Have only made some guesswork about crossover-frequencies.
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Brgds
Lars
Lars
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This transformer was drawn for simulation purpose and it seems to work. Here I speak to the specialist: maybe can you make better ? If you think the above transformer is the best compromise (because all is compromise) so yes, the same. If no, I let you do and suggest. Than you.do you mean a 1:1 bifilar with 50hy's of inductance as drawn in the sims above?
Regards.
Pierre.
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I ran the DC operating point and the current is 30ma. While I can do a 50hy 30ma 300R device, it will be on a larger core than ultimately needed and since these will ultimately be for specific frequencies, I see no need for them to all be the same.
I can do the 50hy @ 30ma if the DCR's go up to 600 ohms per winding or get closer to the 300 ohm number and give 30hy's @ 30ma. I like the idea of going for the lower inductance but let see if Lars has an opinion.
Ultimately you could go with something like 50hy 600R for the bass 30hy 300 ohms for the mids and 15hy 150R (or use a smaller 80% nickel core) for the highs). My sims still show 30hy's in this situation being -1dB at 3hz so i'm not concerned
dave
I can do the 50hy @ 30ma if the DCR's go up to 600 ohms per winding or get closer to the 300 ohm number and give 30hy's @ 30ma. I like the idea of going for the lower inductance but let see if Lars has an opinion.
Ultimately you could go with something like 50hy 600R for the bass 30hy 300 ohms for the mids and 15hy 150R (or use a smaller 80% nickel core) for the highs). My sims still show 30hy's in this situation being -1dB at 3hz so i'm not concerned
dave
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reVintage.reVintage wrote:HI Pierre,
Tried to simplify a little. Have only made some guesswork about crossover-frequencies.
The guesswork about crossover-frequencies at line level be a pin in ass, you would need some like of prototype type of crossover that you might lend in your local pro audio shop… I did not read the thread but I do not like what I see in the picture.
HF: get rid of that C1 and do for RL filter. It is not even arguable in my book
MF: This band passes works but if you have the top knee relatively high or if you objectives are too refined then it will not and you need to convert it into a series resistor and cap and coil to ground. It will give you the same filter but you will have no reactive complement in signal bypass
LF: If you cat off is low than you will have a large inductance with a lot of wire in it. Since it bass you would need a very low DCR that means think wire and very large size. Well, did you try to hide a large size coil inside of an amp? Good luck with that! So, you might want to use the same concept: no reactive elements in series application, or to use a resistor and a cap to ground. You might not like caps but THIS cap will not be a problem as it will only pass the shuntable signal that is NOT in the pass of the channel.
Rgs, Romy the Cat
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ReVintage,reVintage wrote:Romy,
Come back when you have read the whole thread! And don´t give me the advice, better you address your ideas to Prazza or Dave.
As I understand it the thread is primary about Prazza wanting to mate transformers with transistors in a filter of his own design.
I did not give an adviser to YOU but I posted it a public forum. For you it cost as much as you invest into reading my post and if you did not “get” my objectives then it is fine with me. I still did not read the thread and I posted what I posted based upon your image - if the image has nothing to do with content of the thread then what does it do there? The point of all of it is that I spent a LOT of time experimenting, analyzing and listening different line-level crossover topologies in different applications. I have to throw into the mix the proposal that in contrary to many others “soldering” audio people I know sound and I know what to listen while I am listening. If you feel annoyed that I have expressed my observation about the filtering schema proposed in your drawing then discard what I expressed and forget about it – I truly have no need to convince you in anything.
The Cat
Romy and ReVintage, please keep cool. I'm ready to accept any advice.
In the meantime I had worked a little on filter and I have made something a little like Romy suggestion.
Romy, any critic ?
ReVintage, thank you for your advices too, I appreciate a lot to work with you and Dave because I have not your experience. If you could give us results about harmonics simulation.. After I will see with Dave about continuation.
Thank you for all, you people !
Regards,
Pierre
In the meantime I had worked a little on filter and I have made something a little like Romy suggestion.
Romy, any critic ?
ReVintage, thank you for your advices too, I appreciate a lot to work with you and Dave because I have not your experience. If you could give us results about harmonics simulation.. After I will see with Dave about continuation.
Thank you for all, you people !
Regards,
Pierre
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Hey Prazza,
The network loads the driver harder at low frequencies. It will probably be better if you go for as in this case 4,7k all the way to get equal loading independant of frequency.
Personally I would go for lower series-resitances all over. Your driver could easily take something in the ballpark of 2k.
The network loads the driver harder at low frequencies. It will probably be better if you go for as in this case 4,7k all the way to get equal loading independant of frequency.
Personally I would go for lower series-resitances all over. Your driver could easily take something in the ballpark of 2k.
Brgds
Lars
Lars
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Pierre, this is a bit tricky.
The filters look now all right to me, presumably that the values are right. You need to look for the environmental damage. I do not know SS and I have no idea if your transistors will do OK with a cap or inductor sitting right at their base. I do not know if your driver will be able to drive this low impedance. So, you need to look into all of the environmental variables.
What is tricky here is to find out if the different load for different channels will be OK. Of course if you make then the same then you out of muddy water BUT I have seen situation what moderation of LF channel impedance in relation to other channels did make an interning effect. Your MF channels will be no changed but your LF channel will or might. Basically you moderate current that will be reassigned between the channels. In theory current does nothing in this case and you care just about voltage. In practice, if you have very capable LF section, then you can recognize the difference. Back in 2001 I have a 2 pairs of ML2 and I was driving my Bass ML2 with twice higher or lower impedance (I do remember already). It was very auditable difference. Well, in my case I drover cable, so high current “pressed” them harder, that is always better. In your case it might be not a factor – you need to try it. Also, the large amount of magnetics might have some masking effects to your bass quality, so it might be all irrelevant in your case.
The Cat
The filters look now all right to me, presumably that the values are right. You need to look for the environmental damage. I do not know SS and I have no idea if your transistors will do OK with a cap or inductor sitting right at their base. I do not know if your driver will be able to drive this low impedance. So, you need to look into all of the environmental variables.
What is tricky here is to find out if the different load for different channels will be OK. Of course if you make then the same then you out of muddy water BUT I have seen situation what moderation of LF channel impedance in relation to other channels did make an interning effect. Your MF channels will be no changed but your LF channel will or might. Basically you moderate current that will be reassigned between the channels. In theory current does nothing in this case and you care just about voltage. In practice, if you have very capable LF section, then you can recognize the difference. Back in 2001 I have a 2 pairs of ML2 and I was driving my Bass ML2 with twice higher or lower impedance (I do remember already). It was very auditable difference. Well, in my case I drover cable, so high current “pressed” them harder, that is always better. In your case it might be not a factor – you need to try it. Also, the large amount of magnetics might have some masking effects to your bass quality, so it might be all irrelevant in your case.
The Cat
Hi Prazza,
Check your filter once again ! If you buy the concept with a 6H choke picking up hum when in the bass-channel it will pick-up equally much hum when situated in the midchannel.
One shouldn´t mix up what is going on inside the buffered filter with what is happening from the output of the filter to the input of the poweramps. For the input-buffer it is important to see the same load over the entire frequency-spectrum!
Check your filter once again ! If you buy the concept with a 6H choke picking up hum when in the bass-channel it will pick-up equally much hum when situated in the midchannel.
One shouldn´t mix up what is going on inside the buffered filter with what is happening from the output of the filter to the input of the poweramps. For the input-buffer it is important to see the same load over the entire frequency-spectrum!
Brgds
Lars
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Hello Pierre,
The 30hy 30ma was a guess based on using the same wire gauge on the primary and the secondary. This may have been covered but do you want a lower DCR for biasing reasons?
You can think of it this way, both the primary and secondary appear in series for the output impedance so you will have a ~600 ohm resistive Zout (300 + 300 assuming the sand is near 0). nothing says the wire cant be chosen to get a 150 ohm primary but then you end up with a 450 ohm secondary. Essentially the DCR is set by the winding window size and the number of turns. There are two ways to lower the overall DCR and that is a bigger window (larger core which increases $$) or fewer turns which requires the choice of lower inductance / current.
At this point there are just ballpark guesses (+- say 20%) and I'd have to wind and measure a sample to get accurate numbers.
dave
The 30hy 30ma was a guess based on using the same wire gauge on the primary and the secondary. This may have been covered but do you want a lower DCR for biasing reasons?
You can think of it this way, both the primary and secondary appear in series for the output impedance so you will have a ~600 ohm resistive Zout (300 + 300 assuming the sand is near 0). nothing says the wire cant be chosen to get a 150 ohm primary but then you end up with a 450 ohm secondary. Essentially the DCR is set by the winding window size and the number of turns. There are two ways to lower the overall DCR and that is a bigger window (larger core which increases $$) or fewer turns which requires the choice of lower inductance / current.
At this point there are just ballpark guesses (+- say 20%) and I'd have to wind and measure a sample to get accurate numbers.
dave
Dave,
I asked that to have lower output impedance not for bias (this is ok). I already have a preamp with OPT and I have measured DCR of secondary around 8 ohms. But maybe this OPT is used in Parallel Feed Single-Ended (with capacitor) mode so maybe with low primary and secondary DCR. Your opinion ?
Pierre
I asked that to have lower output impedance not for bias (this is ok). I already have a preamp with OPT and I have measured DCR of secondary around 8 ohms. But maybe this OPT is used in Parallel Feed Single-Ended (with capacitor) mode so maybe with low primary and secondary DCR. Your opinion ?
Pierre
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I ran the step command in spice to look at the inductances and dropping it to 3hy only makes a slight visible change so how about something like 6hy to be "safe" If we come up with a realistic inductance that you are happy with then i'll see what the DCR will be.
dave
dave
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