Calling my great and unpaid crossover consultants. If I put a high power variable pot (say two outside legs of a speaker lpad at the tweeter crossover input ( where protection relay was) will this affect level only with minimum impact on crossover frequency, as it might eight at the tweeter side? Thank you guys a lot, variable tweeter level is need on this unit in my situation.
I assume you're saying the tweeter is too bright? 🙂
You don't use an L-pad at the tweeter input with a zobel fitted to the tweeter. You just use a series resistor at the tweeter filter input. Since the rough zobel gives a tweeter impedance around 6 ohms, a 2.2R or 3.3 R 7W wirewound is indicated for fairly substantial level reduction around 3dB.
This won't mess up the crucial phase relationship. I've enjoyed this thread a lot. It's opened my eyes to how you get a 1" tweeter working with an 8" bass. Low order filter on the tweeter doesn't hack it. You need a shallow fourth order, which has a built in time delay. 😎
You don't use an L-pad at the tweeter input with a zobel fitted to the tweeter. You just use a series resistor at the tweeter filter input. Since the rough zobel gives a tweeter impedance around 6 ohms, a 2.2R or 3.3 R 7W wirewound is indicated for fairly substantial level reduction around 3dB.
This won't mess up the crucial phase relationship. I've enjoyed this thread a lot. It's opened my eyes to how you get a 1" tweeter working with an 8" bass. Low order filter on the tweeter doesn't hack it. You need a shallow fourth order, which has a built in time delay. 😎
That's what I mean Steve, I will use an 8 ohm pot at the input, which in this case is exactly where the old tweeter protection relay was. A variable high power 0 to 8 ohm wirewound series resistor (pot) instead of a fixed value nothing wrong with that is there?
Damn! Another mystery, when I manually disengage the relay as a test the entire speaker cuts out, not just thetweeter!!
WTH?
WTH?
So since this relay is single point it must be throwing a common point to not t and woofs, but I will be damned if I see that. My schematic reading skills, at least on this one must really be bad, glad I'm not geeking diy medical gear.
^ I meant common to both tweeter and woofer. In any event an 8r series pot between the relay and C5 which is apparently the input of the hi side of the xover should give me tweeter level control without altering crossover I am assuming hopefull?
I see, I was incorrect, its the juncture of l4 and C6 that is the real input of the HF section and it is there I must insert the series resistance correct?
Ok guys I am very sorry, the entry point is at C5 as Mr. Chau poointed out. What is not in the circuit and is present on all three boards I have is a soldered on jumper wire between C5 and L1, plus some other minor changes in layout. These are revisions.
Hi Pete
I don't quite understand. If there's a jumper wire from L1 to C5, what it means is that the Protection Relay and it's associated circuit is bypassed.
The output of your 8 ohm pot should be connected to C5. The question now is where the input should be connected. Is the jumper on the pcb from L1 to C5 or to Relay where R13 is?
Regards
Mike
I don't quite understand. If there's a jumper wire from L1 to C5, what it means is that the Protection Relay and it's associated circuit is bypassed.
The output of your 8 ohm pot should be connected to C5. The question now is where the input should be connected. Is the jumper on the pcb from L1 to C5 or to Relay where R13 is?
Regards
Mike
Hi Michael, there are other revisions, what I did was cut a trace then then woofer and tweeter were separates from the relay, rerouted the woofer back on the other side of trace, the resister is now between one side of the ( closed ) relay and C5. So far its seems to be ideally working with my test resistors of 4 ohms a bit too low, so I think I will have it with the 8r pot.
Thanks Michael!
Ok, here is where I am. At this point we probably know as much about these units as anyone (-: This thread is hopefully going to make life easier for whoever is next rebuilding these units. They *are* worth the effort.
Again, the people on this group here are nothing short of awesome, a word I do not throw around like grains of sand or salt.
To clarify, the factory (or a factory field revision) has put a jumper wire between the relay terminal point that is common to both tweeter and woofer terminal and inductor L1. This jumper wire is present on *all three* crossovers units in my possession, two revisions total, 2 of them from 1986, one from 1987 all intended for the Matrix series 1 speakers that I have, not for the later series 2 from 88 0r 89 or so.
How they made the one point relay common to both T and W's in that circuit I know not, but that relay is indeed common. I have verified this by opening the relay manually. Doing so is a full stop for the entire speaker speaker, not just the tweeter. What I did was cut the trace between C5 and the relay and jumped the woofer back into the circuit on woofer to relay side of the cut but leaving the circuit open between C5 (tweeter xover input) and the relay.. I then soldered leads to both sides of the trace I cut now between relay and leading back to L5 and placed them outside of the speaker for to insert various low resistor values for testing..
Here is what I have found. I have two 10 watt 4 ohm resistors here currently, using so parallel or series or alone I have 8, 4 and two ohms to work worth until and if I obtain the pots.
8 ohm?of course too much series resistance,
4 ohms too much still,
2 ohms? Damn near perfect! Only a *tiny* bit laid back, perhaps and by measurement against my other units around 1 db too low.
*I'm guessing my next step down will be 1.6 ohms does that sound about right?*
If I can get there I will forgo using pots. Seems to me that System 7 had me somewhere in that range around 20 posts or go, damn you guys are good, no gratuitous crap here either, you really are.
Were I not a mix/master guy I probably would never hear it or care, but *this is a game of inches*, It's not necessarily true that you can just buy more accurate speakers, I am there , I am doing that. .Through the years I have found that one will wind up adjusting both the room and speakers until, that perfect "pocket" is hit, most guys who do what I do know that pocket when they hear it and that pocket is very small, smaller than most speaker/room combos are capable of attaining. Even the very best, Dunlavy's Nautilus etc. need many room tweaks, many positioning tweaks to hit that pocket, so it is worth working with a good speaker when you think you have one, even if it's not a 50,000 speaker. Some of the best units for this job are available for less than $2000 that is a fact.
All of this is off topic, but hopefully it explains why I've went to all this effort and asked for so much help with what must seem like overly anal minutia to some of you veteran speaker building guys.
Ok, here is where I am. At this point we probably know as much about these units as anyone (-: This thread is hopefully going to make life easier for whoever is next rebuilding these units. They *are* worth the effort.
Again, the people on this group here are nothing short of awesome, a word I do not throw around like grains of sand or salt.
To clarify, the factory (or a factory field revision) has put a jumper wire between the relay terminal point that is common to both tweeter and woofer terminal and inductor L1. This jumper wire is present on *all three* crossovers units in my possession, two revisions total, 2 of them from 1986, one from 1987 all intended for the Matrix series 1 speakers that I have, not for the later series 2 from 88 0r 89 or so.
How they made the one point relay common to both T and W's in that circuit I know not, but that relay is indeed common. I have verified this by opening the relay manually. Doing so is a full stop for the entire speaker speaker, not just the tweeter. What I did was cut the trace between C5 and the relay and jumped the woofer back into the circuit on woofer to relay side of the cut but leaving the circuit open between C5 (tweeter xover input) and the relay.. I then soldered leads to both sides of the trace I cut now between relay and leading back to L5 and placed them outside of the speaker for to insert various low resistor values for testing..
Here is what I have found. I have two 10 watt 4 ohm resistors here currently, using so parallel or series or alone I have 8, 4 and two ohms to work worth until and if I obtain the pots.
8 ohm?of course too much series resistance,
4 ohms too much still,
2 ohms? Damn near perfect! Only a *tiny* bit laid back, perhaps and by measurement against my other units around 1 db too low.
*I'm guessing my next step down will be 1.6 ohms does that sound about right?*
If I can get there I will forgo using pots. Seems to me that System 7 had me somewhere in that range around 20 posts or go, damn you guys are good, no gratuitous crap here either, you really are.
Were I not a mix/master guy I probably would never hear it or care, but *this is a game of inches*, It's not necessarily true that you can just buy more accurate speakers, I am there , I am doing that. .Through the years I have found that one will wind up adjusting both the room and speakers until, that perfect "pocket" is hit, most guys who do what I do know that pocket when they hear it and that pocket is very small, smaller than most speaker/room combos are capable of attaining. Even the very best, Dunlavy's Nautilus etc. need many room tweaks, many positioning tweaks to hit that pocket, so it is worth working with a good speaker when you think you have one, even if it's not a 50,000 speaker. Some of the best units for this job are available for less than $2000 that is a fact.
All of this is off topic, but hopefully it explains why I've went to all this effort and asked for so much help with what must seem like overly anal minutia to some of you veteran speaker building guys.
Last edited:
Ok I thinkI understand this, we are still talking about a 6 ohm nominal tweeter circuit? I am assuming this might still apply here with even the zobels and delay circuits
1 db, 0.75 ohms.
2-dB, 1.6 ohms
3 dB, 2.5 ohms,
4 dB 3.5 ohms
5 dB 4.7 ohms ?
well I do think this is roughly analogous to what I am hearing.
I'm thinking it was overall about a 2db rise in tweeter level that's been bugging me. Right now I have 2.2 ohms because that is what I had laying around (a 5 plus a 4 in parallel) that could do both sides with. it now around 1.5 to 2 db too low, so I'm thinking somewhere between 1 and 1.6 ohms I am going to hit the pocket huh?
1 db, 0.75 ohms.
2-dB, 1.6 ohms
3 dB, 2.5 ohms,
4 dB 3.5 ohms
5 dB 4.7 ohms ?
well I do think this is roughly analogous to what I am hearing.
I'm thinking it was overall about a 2db rise in tweeter level that's been bugging me. Right now I have 2.2 ohms because that is what I had laying around (a 5 plus a 4 in parallel) that could do both sides with. it now around 1.5 to 2 db too low, so I'm thinking somewhere between 1 and 1.6 ohms I am going to hit the pocket huh?
Try parallel resistors.
1) 2 ohms parallel with 8 ohms = 1.6 ohms
2) 2 ohms parallel with 4 ohms = 1.33 ohms
3) 2 ohms; 4 ohms; 8 ohms in parallel = 1.14 ohms
When you get the right value, the music will "snap" in.
1) 2 ohms parallel with 8 ohms = 1.6 ohms
2) 2 ohms parallel with 4 ohms = 1.33 ohms
3) 2 ohms; 4 ohms; 8 ohms in parallel = 1.14 ohms
When you get the right value, the music will "snap" in.
Edit* Oh I see you were giving me "cheat sheet" to get to my values! Duh!
Thanks. I am calculating a that my current 5 ohm resister parallel to my 4 ohm resister is giving me a total resistance of 2.2 ohms which I am now placing as per instructions between C5 and relay and I am almost there, it actually is "snapping in, I am near the window of perfection for this room but think I am hearing around 1 to 1.5 db too low. If I wish to raise the tweeter level now by a db or two I am going to need to decrease my resistance there by about half perhaps, if I am getting this right? These tweeters DCR at 5.9 ohms and I do know the Zobels and delay circuit are going to make this hard to calculate so this is going to be ear work as opposed to calclations, just trying to guess closer to the goal before I buy resistors.
Thanks. I am calculating a that my current 5 ohm resister parallel to my 4 ohm resister is giving me a total resistance of 2.2 ohms which I am now placing as per instructions between C5 and relay and I am almost there, it actually is "snapping in, I am near the window of perfection for this room but think I am hearing around 1 to 1.5 db too low. If I wish to raise the tweeter level now by a db or two I am going to need to decrease my resistance there by about half perhaps, if I am getting this right? These tweeters DCR at 5.9 ohms and I do know the Zobels and delay circuit are going to make this hard to calculate so this is going to be ear work as opposed to calclations, just trying to guess closer to the goal before I buy resistors.
Last edited:
- Status
- Not open for further replies.