I'm looking for some help please... I'll try to keep it short:
I just made a set of OB speakers using an Eminence 12LTA used full range. I also added a 1" Eminence tweeter. Both drivers are 8 ohms.
I first hooked them up in parallel and ran them from my 2A3 SET amp, the sound was very good, I was happy. Then I learned that the two drivers wired in parallel present a 4 ohm load to my amp which is not the best way to run. So... I wired them in series to present a 16 ohm load to my amp, I changed the lead on the OPT to the 16 ohm position and they sounded good as well, but the tweeters were way too bright.
I read up on how to reduce tweeter output by the use of added series resistance and nothing I add seems to help.
What am I doing wrong? Any help is appreciated., thanks.
I just made a set of OB speakers using an Eminence 12LTA used full range. I also added a 1" Eminence tweeter. Both drivers are 8 ohms.
I first hooked them up in parallel and ran them from my 2A3 SET amp, the sound was very good, I was happy. Then I learned that the two drivers wired in parallel present a 4 ohm load to my amp which is not the best way to run. So... I wired them in series to present a 16 ohm load to my amp, I changed the lead on the OPT to the 16 ohm position and they sounded good as well, but the tweeters were way too bright.
I read up on how to reduce tweeter output by the use of added series resistance and nothing I add seems to help.
What am I doing wrong? Any help is appreciated., thanks.
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Hi
You can't wire them in series properly without using a series x/o.
The impedance will then be 8 ohms, as it will be using a
parallel x/o, or only using a parallel x/o on the tweeter
with the bass unit full range in parallel.
You need a minimum of a series capacitor on the tweeter,
(high x/o frequency) and an L-pad to adjust the tweeter level.
rgds, sreten.
You can't wire them in series properly without using a series x/o.
The impedance will then be 8 ohms, as it will be using a
parallel x/o, or only using a parallel x/o on the tweeter
with the bass unit full range in parallel.
You need a minimum of a series capacitor on the tweeter,
(high x/o frequency) and an L-pad to adjust the tweeter level.
rgds, sreten.
I need to reduce the tweeter output by 9dB, so I calculated the resistance of both the parallel and series resistors by use of the formula on this page: L-Pad Driver Attenuation Circuit) Designer / Calculator Help
The series resistor calculated out to be 3 ohms and the parallel resistor calculated out to be 4.5 ohms. After I wired them in, no change.
The series resistor calculated out to be 3 ohms and the parallel resistor calculated out to be 4.5 ohms. After I wired them in, no change.
I'm not using any crossover. The 12LTA runs full range from my amp and the tweeter used a 1.0uF cap to which I added the parallel and series resistance I posted above.
Thanks for the replies so far. I did just place an order for two L pads, I'll have them in a few days to try out.
Thanks for the replies so far. I did just place an order for two L pads, I'll have them in a few days to try out.
Running the two drivers in parallel with a cap on the tweeter is fine. Run them in series and you are filtering bass from both drivers hence the sound will be bright.
Hi, that is simply not possible, you have made some sort of error, rgds, sreten.
Probably the series connection is just totally wrong, with no bass possible.
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Ok, lots to learn on my behalf, so I appreciate the input...
Bootsale: Understood, it never occurred to but you're right in your comment about filtering from both because they're in series.
streten: Thanks, I'll go back and look at my calculation again
Charlielaub: No it doesn't
Since I have ordered the L Pads, am I OK to leave the wiring in series, and just install the L Pad on the tweeters and adjust until OK?
Bootsale: Understood, it never occurred to but you're right in your comment about filtering from both because they're in series.
streten: Thanks, I'll go back and look at my calculation again
Charlielaub: No it doesn't
Since I have ordered the L Pads, am I OK to leave the wiring in series, and just install the L Pad on the tweeters and adjust until OK?
Pano: Yes, I kind of thought that was the way to go, because I've had nothing but trouble working with the series wiring... but I was concerned about the 4 ohm load on my SET tube amp, shouldn't I be?
I was scratching my head here along with everybody else, no doubt. 
Below seems to be the right way to do the parallel filter as described.
Seems OK. The series version becomes a sort of midrange filter. If you foolishly put the 1uF AFTER the attenuator, it peaks up into the upper midrange, then falls away to nothing. 😱
(Where do people get these nicks from? However do you pronounce Mijknarf. 😀 )
Below seems to be the right way to do the parallel filter as described.
Seems OK. The series version becomes a sort of midrange filter. If you foolishly put the 1uF AFTER the attenuator, it peaks up into the upper midrange, then falls away to nothing. 😱
(Where do people get these nicks from? However do you pronounce Mijknarf. 😀 )
Attachments
Let me take a look at your drawings...thanks for the help.
Actually, we all have to start somewhere with this hobby, so I'm not posting to impress, rather, I'm trying to learn. Any suggestion made here, I'll have to run down until I understand what works. I'm sure I'll come out of this much more knowledgeable than I entered. Thanks to the many who have responded.
My name is pronounced the same way you pronounce any other words, sound it out, not that tough... its actually my name backwards.
Actually, we all have to start somewhere with this hobby, so I'm not posting to impress, rather, I'm trying to learn. Any suggestion made here, I'll have to run down until I understand what works. I'm sure I'll come out of this much more knowledgeable than I entered. Thanks to the many who have responded.
My name is pronounced the same way you pronounce any other words, sound it out, not that tough... its actually my name backwards.
You'll get it, don't worry.We all had to start somewhere and you've done well to ask up front.
To many of us here it seems super simple, but that's because we've done it for so long. It wasn't simple when we started. 🙂
System7's diagram will but you on the right path. You can replace the resistors with your L-Pads when they arrive - that will allow some tuning.
To many of us here it seems super simple, but that's because we've done it for so long. It wasn't simple when we started. 🙂
System7's diagram will but you on the right path. You can replace the resistors with your L-Pads when they arrive - that will allow some tuning.
Just as well we don't have any members called Natas then, mijknarf...we don't, do we? 😀
High efficiency is a nice topic. Troels Gravesen does interesting things with a Monacor whizzer-coned fullrange here, adding a ribbon tweeter:
Monacor SP200X +
My favourite SET-friendly fullrange article is Morgan Jones' Arpeggio speaker:
http://www.diyaudio.com/forums/diyaudio-com-articles/158899-arpeggio-loudspeaker.html
Be interested to know the exact drivers you are attempting to integrate here.
High efficiency is a nice topic. Troels Gravesen does interesting things with a Monacor whizzer-coned fullrange here, adding a ribbon tweeter:
Monacor SP200X +
My favourite SET-friendly fullrange article is Morgan Jones' Arpeggio speaker:
http://www.diyaudio.com/forums/diyaudio-com-articles/158899-arpeggio-loudspeaker.html
Be interested to know the exact drivers you are attempting to integrate here.
The Beta 12 LTA is a well known fullrange driver that sounds much better than it ought to, given it's appearance and price. The top end can be tricky to properly crossover because of the whizzer.
As for the 1" tweeter, are you using the APT-50 or a 1" compression driver and horn?
As for the 1" tweeter, are you using the APT-50 or a 1" compression driver and horn?
Assuming that the full-range driver is active within the pass-band of the tweeter, this means that, in that common frequency range, the total load presented to the amp is the load of the two drivers in parallel. So this means that the amp will see (about) a 4 Ohm load in the higher frequency range. This of course only applies to "hooking them up in parallel".
Okay, well scratch that if the cap in-series with the tweeter is 1 uF. Then the tweeter in that arrangement is a "super" tweeter and operating above the high-end response of the full-range driver.
Regards,
Pete
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Pano: The tweeter is an Eminence ASD1001 horn driver with a wave guide. I actually copied its use from Godzilla here who mated it with the 12LTA.
MCPete: Yes, I used a 1uF cap in series with the tweeter and all was well when I hooked them up in parallel, but, as the novice I am, I thought a series connection would be better for my amp, that is where things went south.
MCPete: Yes, I used a 1uF cap in series with the tweeter and all was well when I hooked them up in parallel, but, as the novice I am, I thought a series connection would be better for my amp, that is where things went south.
OK, let me see if I have this right:
1. The cap on the tweeter, when wired in parallel only effected the tweeter, but when wired in series, the cap effected the 12LTA driver as well which accentuated the high end even more. When I started to add resistance to the tweeter, the resistors also affected the full ranger and totally screwed with everything.
2. The 8 ohm tweeter (with series 1uF cap) wired in parallel with the 8 ohm full range, really doesn't present a 4 ohm load to the amp except in the range the two drivers overlap.
I'm just going to go back to parallel wiring, insert the 1uF cap in series with the tweeter and I'll be back where I started, which was a good place. I thought I was doing something good with the series move, but lost control.
One more question... if I were to add the L Pads to the tweeter when wired in series, wouldn't they also affect the output of the full ranger?
Jim
1. The cap on the tweeter, when wired in parallel only effected the tweeter, but when wired in series, the cap effected the 12LTA driver as well which accentuated the high end even more. When I started to add resistance to the tweeter, the resistors also affected the full ranger and totally screwed with everything.
2. The 8 ohm tweeter (with series 1uF cap) wired in parallel with the 8 ohm full range, really doesn't present a 4 ohm load to the amp except in the range the two drivers overlap.
I'm just going to go back to parallel wiring, insert the 1uF cap in series with the tweeter and I'll be back where I started, which was a good place. I thought I was doing something good with the series move, but lost control.
One more question... if I were to add the L Pads to the tweeter when wired in series, wouldn't they also affect the output of the full ranger?
Jim
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