crossover with l-pad, bypassing the l-pad?

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EZHusky

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crossover with l-pad, bypassing the l-pad?
« on: 11 Dec 2018, 04:30 am »
so i plugged in the teacs, and i found that one of the l-pads are broken. so im wondering if i can just get rid of it all together so i wont have to worry about it, since i have no idea how i would fix it.







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« Last Edit: 12 Jan 2019, 10:26 pm by EZHusky »

S Clark

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Re: crossover with dial, how do you bypass the dial?
« Reply #1 on: 11 Dec 2018, 05:16 am »
Take a volt/ohm meter and measure the resistance of the working one as you turn the knob.  Replace the variable resistor with a resistor value near the middle of the readings- and with at least a 5 watt rating.  I bet that it controls the volume of the tweeter.  Want more treble? Use a smaller value. Want less, use a larger one. That should get you a usable crossover. 

But it's hard to see exactly from the photo, so who knows, these changes could cause it to spontaneously ignite.

EZHusky

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Re: crossover with dial, how do you bypass the dial?
« Reply #2 on: 11 Dec 2018, 05:23 am »
But it's hard to see exactly from the photo, so who knows, these changes could cause it to spontaneously ignite.
That's comforting, would you like more pictures? Also do you think it would be a good idea to completely remake the crossover with all new parts? Since this fix requires spending money I would like to make it nicer instead of just "alright"

jules

Re: crossover with dial, how do you bypass the dial?
« Reply #3 on: 11 Dec 2018, 05:37 am »
When you say the "dial" is broken, does that mean you can't adjust it at all?

It's probably an L-pad. Easiest way to understand that is to google L-pad.

See if you can read enough part numbers off the broken item to look up. Part numbers are often easy to search, given they're unique. Best fix that allows you to adjust the tweeter according to your room, would be to replace the broken part with a new one and as S Clark says, if you can, check the current adjustment.

Here's an example:

https://www.parts-express.com/parts-express-speaker-l-pad-attenuator-100w-mono-3-8-shaft-8-ohm--260-262

If the capacitors are getting a little old, it would help to replace them and maybe upgrade them.

S Clark

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Re: crossover with dial, how do you bypass the dial?
« Reply #4 on: 11 Dec 2018, 05:49 am »
Well, it's not likely that you'll burn down the house... but a low rated resistor in a woofer circuit actually could do just that.  Luckily, most L pads are in the tweeter circuit.   Close up photos might help.    What is under those metal brackets? Coils (inductors)?  If so and if they're steel, I'd get rid of those brackets and hot glue the coils in place or use some zip ties. 
Which model of Teac is this?  Maybe there are schematics of the crossover available on line.  That would be helpful. 

EZHusky

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Re: crossover with dial, how do you bypass the dial?
« Reply #5 on: 11 Dec 2018, 06:05 am »
When you say the "dial" is broken, does that mean you can't adjust it at all?

It's probably an L-pad. Easiest way to understand that is to google L-pad.

See if you can read enough part numbers off the broken item to look up. Part numbers are often easy to search, given they're unique. Best fix that allows you to adjust the tweeter according to your room, would be to replace the broken part with a new one and as S Clark says, if you can, check the current adjustment.

Here's an example:

https://www.parts-express.com/parts-express-speaker-l-pad-attenuator-100w-mono-3-8-shaft-8-ohm--260-262

If the capacitors are getting a little old, it would help to replace them and maybe upgrade them.
The dial makes it sound like you are covering your head with a pillow or if you were underwater (I don't know how else to explain it) like all you hear is the lows, and I say it is the dial because if you turn the dial on the other one it fixes itself (the other dial is broken but sounds good if you turn it all the way up)

EZHusky

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Re: crossover with dial, how do you bypass the dial?
« Reply #6 on: 11 Dec 2018, 06:06 am »
Well, it's not likely that you'll burn down the house... but a low rated resistor in a woofer circuit actually could do just that.  Luckily, most L pads are in the tweeter circuit.   Close up photos might help.    What is under those metal brackets? Coils (inductors)?  If so and if they're steel, I'd get rid of those brackets and hot glue the coils in place or use some zip ties. 
Which model of Teac is this?  Maybe there are schematics of the crossover available on line.  That would be helpful.
I'll be getting better pictures Tomorrow, and the model is the teac -ls350, I've tried looking them up but I can't find anything on them

FullRangeMan

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Re: crossover with dial, how do you bypass the dial?
« Reply #7 on: 11 Dec 2018, 11:30 am »
I fail to see any in this dark images.

EZHusky

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Re: crossover with dial, how do you bypass the dial?
« Reply #8 on: 11 Dec 2018, 01:48 pm »
I fail to see any in this dark images.
You fail to see what? And if you read the comments you would see that I'm going to get better pictures.

S Clark

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Re: crossover with dial, how do you bypass the dial?
« Reply #9 on: 11 Dec 2018, 02:10 pm »
You have to understand that FullRangeMan's native language isn't English, but Portuguese.  He is very knowledgeable, but sometimes communication can be flawed. 
AFter looking around for your Teac, I think I'd follow Jules' advice and just pick of two of those L Pads from partsexpress.com.
It looks like everything in your speaker is 8 ohm, so I'd replace the old Lpad in both so that they would perform the same.  These appear to be big old 12" three ways from the late 70's or early 80's.  I don't see a port, and if they are sealed, they may offer a decently quick response for big speakers.  They're definitely worth repair, but I wouldn't go down the upgrade rabbit hole very far. 

FullRangeMan

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Re: crossover with dial, how do you bypass the dial?
« Reply #10 on: 11 Dec 2018, 03:07 pm »
You fail to see what? And if you read the comments you would see that I'm going to get better pictures.
I understand all perfectly, I read english since the 1970s.
Not need take new photos, there is better images on the web.
Current audiophiles like to fix what is not broken.
Your comments dont inform electrical values, remove the pot not need any xover change, its not recommended as it will lost all the vintage value of this speaker and will remove part from the original mid-fi raw sound.

It even say its a 3way xover but have only 2 speakers.
The woofer is Alnico and well regarded as vintage sound.


EZHusky

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Re: crossover with dial, how do you bypass the dial?
« Reply #11 on: 11 Dec 2018, 03:18 pm »
I understand all perfectly, I read english since the 1970s.
Not need take new photos, there is better images on the web.
Current audiophiles like to fix what is not broken.
Your comments dont inform electrical values, remove the pot not need any xover change, its not recommended as it will lost all the vintage value of this speaker and will remove part from the original mid-fi raw sound.

It even say its a 3way xover but have only 2 speakers.
The woofer is Alnico and well regarded as vintage sound.



xover = crossover (?)
Sorry that I didn't post any of the specs of the crossover, I don't know much about them. Also is is a 3 way, one of the speakers are hidden inside the wood box between the woofer and tweeter

EZHusky

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Re: crossover with dial, how do you bypass the dial?
« Reply #12 on: 11 Dec 2018, 03:22 pm »
You have to understand that FullRangeMan's native language isn't English, but Portuguese.  He is very knowledgeable, but sometimes communication can be flawed. 
AFter looking around for your Teac, I think I'd follow Jules' advice and just pick of two of those L Pads from partsexpress.com.
It looks like everything in your speaker is 8 ohm, so I'd replace the old Lpad in both so that they would perform the same.  These appear to be big old 12" three ways from the late 70's or early 80's.  I don't see a port, and if they are sealed, they may offer a decently quick response for big speakers.  They're definitely worth repair, but I wouldn't go down the upgrade rabbit hole very far.

Alright, I will definitely be replacing the l-pads,

FullRangeMan

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Re: crossover with dial, how do you bypass the dial?
« Reply #13 on: 11 Dec 2018, 03:38 pm »
one of the speakers are hidden inside the wood box between the woofer and tweeter
In this case of 3 ways its more difficult to get good results,
contact Jeff at the Sonic Craft Circle:
https://www.audiocircle.com/index.php?board=201
Change the thin wiring to Teflon occ copper could be an sound improvement.
http://www.soniccraft.com/index.php/neotech-wire-teflon-solid-cu-c-296_175_183_221

EZHusky

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Re: crossover with dial, how do you bypass the dial?
« Reply #14 on: 11 Dec 2018, 03:53 pm »
one of the speakers are hidden inside the wood box between the woofer and tweeter
In this case of 3 ways its more difficult to get good results,
contact Jeff at the Sonic Craft Circle:
https://www.audiocircle.com/index.php?board=201
Change the thin wiring to Teflon occ copper could be an sound improvement.
http://www.soniccraft.com/index.php/neotech-wire-teflon-solid-cu-c-296_175_183_221
That was already ihe plan lol, I definitely will be looking into and upgrading the wire, do you think I could get away with just upgrading to some solid core wire that I have laying around? What guage?

S Clark

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Re: crossover with dial, how do you bypass the dial?
« Reply #15 on: 11 Dec 2018, 08:46 pm »
I would bet that issues with the factory drivers and crossover would more than overshadow any changes wire might offer.  However, better caps might be noticeable.  You could put Sonicaps in place of what appears to be two electrolytic caps.  Probably the most improvement might be from working on the box.  I'd think about adding some deadening to the front and back baffles.  The fiberglass is good, but doesn't help much with lower frequencies.  I like No Rez of all the commercial products, but there are DIY options as well.  Two sheet would be plenty, and one would be enough to help.  http://gr-research.com/norez24x27sheet.aspx

FullRangeMan

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Re: crossover with dial, how do you bypass the dial?
« Reply #16 on: 11 Dec 2018, 10:32 pm »
That was already ihe plan lol, I definitely will be looking into and upgrading the wire, do you think I could get away with just upgrading to some solid core wire that I have laying around? What guage?
I could not ''upgrade'' to a regular wire on hand, but to any real good as these Neotech which are a mid price range no expensive as Mundorf silver+gold, there is Neotech PVC jacketed less expensive than Teflon, awg 14/16 could be suited.

There is some inexpensive passive upgrade treatments to the internal box and yet keep the xover in stock condition:
https://www.audiocircle.com/index.php?topic=100689.0

EZHusky

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Re: crossover with dial, how do you bypass the dial?
« Reply #17 on: 11 Dec 2018, 11:30 pm »
So in the course of me leaving them playing music while I was at school, they fixed themselves! Still looking to improve them quite abit to see if I can get the best sound possible out of them.




S Clark

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Re: crossover with dial, how do you bypass the dial?
« Reply #18 on: 12 Dec 2018, 01:54 am »
Fixed themselves means an intermittent connection in the LPad.  I'd still replace them at your leisure.

EZHusky

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Re: crossover with dial, how do you bypass the dial?
« Reply #19 on: 12 Dec 2018, 02:44 am »
Fixed themselves means an intermittent connection in the LPad.  I'd still replace them at your leisure.
I will still be doing that, as I don't want them to break again