Model 19 Ground Bypass Mods Revisted !

I'm reposting this info for "Russ in Ohio"

Russ,

I looked for the thread,but it seems after the changeover a lot of the pictures,and links seem to be missing,or not working so here it is again. I tried to draw a very simple diagram in the paint program. I just labeled the 4 rivets clockwise for simplification with the inductors/coils and L-pads directly above rivets 1-2 when looking at the diagram.If you just solder a black ground wire from rivet 1 to Rivet 2 and then from 2 to 3 and then 3 to 4 you will bypass the ground rivets that hold the terminal strips to the Aluminum plate.Very easy to follow.In the picture I forgot to label the ground wire that goes from 2 to 3,it follows the yellow wire in the photo.If you look close you will see it.Also in the second photo you can see where the ground wire is on the outside of the terminal strip.You really need to get these XO mods done the 19's will get better I promise you that.Maybe you should give Dave Wojo a call ... Thanks Again for the well wishes !! :smile2:

All The Best !


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And here is the picture that I posted previously that shows how Altec did the ground jumpers at the factory during the last days of production for the 19s.

AH!.....Ok NOW I get it....clearly. Thanks John and Tim......sorry I had a hard time understanding this.


I'm considering doing this mod this coming weekend. I've already replaced all the crossover wiring a few years back because the factory wiring was very "spindly".....and some of the original solder joints were quite weak.

Other than wiring......I plan to keep my crossovers bone-stock.......as I want the 19's to keep their original "voice". I'm guessing however.....that this tweak to the ground rivets will surely benefit that original factory "voice" due to the oxidation over the years within the mechanical connection of these rivets.

Who knows? It is entirely possible that the ground rivets on my particular crossovers are so firmly attached metal-to-metal that no hard wire is needed....but it sounds like a great idea anyway.


Thanks guys, tremendous help!

Russ

Hey Russ ! Cool, I'm glad your getting a hold on it ! The rebuild will keep your crossovers completely stock.Your just replacing component for component when changing out the caps and resistors. If you don't have a meter to check the values on the resistors ? I would just go ahead and change them out anyway, they are cheap, couple bucks each.They (Components) are over 30 years old now and are no doubt out of spec I'm willing to bet.On mine 2 of the 4 resistors on each one were out and most of the caps.A long with the bypass,you will have a much better performing 19 IMHO. Mine had a dramatic improvement. Good Luck with it.

You will love the improvement ! :wink2:

Hi there,

I've been reading a lot of posts the last few years, but I just recently joined as a member. I tried to PM you regarding the Model 19 x-over rebuild, but I guess I need 10 posts first so I had to post my question here. Sorry to everyone if some ( most ) of these questions are redundant, and if you don't have time to answer I completely understand.

I picked up a set of stock 19's about a year ago and would now like to have the x-overs rebuilt. I've read a lot of info and opinions, but I think I'm going to go the path that you've suggested using Dayton or Jantzen caps. Unfortunately I'm not a tech at all, so I'll be having someone else do all the assembly. I was wondering if there is any chance you could send me a list of what caps / resistors to use and the values I need to order as I get the impression the exact values aren't available in some cases? I've tried to research the different Altec forums, but there's so many opinions on types ( PIO,metal/poly,film,charge coupled,etc. ) and I have really no idea about that stuff. Don't want to order/use the wrong thing.

I may try and clean the pots but I will be leaving them and the coils alone as you suggested, as I definitely want to retain / regain that classic Altec voicing. I think I understand what has to be done for the grounding of the lugs. Would you suggest leaving the original L-pads in or replacing them as well? I'll print out a schematic to take with me to wherever I get the work done, but I would like to be able to give them as much info as I can on what exactly I want done in order to avoid any issues.

Thanks for posting all the great tips, and for any additional advice you might be able to offer. If not, no worries and sorry to bother you. Thanks and take care.

Mike

Quote:

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Originally Posted by mac24

Hi there,

I've been reading a lot of posts the last few years, but I just recently joined as a member. I tried to PM you regarding the Model 19 x-over rebuild, but I guess I need 10 posts first so I had to post my question here. Sorry to everyone if some ( most ) of these questions are redundant, and if you don't have time to answer I completely understand.

I picked up a set of stock 19's about a year ago and would now like to have the x-overs rebuilt. I've read a lot of info and opinions, but I think I'm going to go the path that you've suggested using Dayton or Jantzen caps. Unfortunately I'm not a tech at all, so I'll be having someone else do all the assembly. I was wondering if there is any chance you could send me a list of what caps / resistors to use and the values I need to order as I get the impression the exact values aren't available in some cases? I've tried to research the different Altec forums, but there's so many opinions on types ( PIO,metal/poly,film,charge coupled,etc. ) and I have really no idea about that stuff. Don't want to order/use the wrong thing.

I may try and clean the pots but I will be leaving them and the coils alone as you suggested, as I definitely want to retain / regain that classic Altec voicing. I think I understand what has to be done for the grounding of the lugs. Would you suggest leaving the original L-pads in or replacing them as well? I'll print out a schematic to take with me to wherever I get the work done, but I would like to be able to give them as much info as I can on what exactly I want done in order to avoid any issues.

Thanks for posting all the great tips, and for any additional advice you might be able to offer. If not, no worries and sorry to bother you. Thanks and take care.

Mike

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Hi Mike,

All the info you need are in these threads.All the info you need should be here, but of course if you have any other questions. I would be happy to answer them..

I would use Solen Fast Caps 250v or 400v are fine..Leave the coils ! They very rarely ever go bad, and is a waste of money IMHO.. The parts you may have to source from 2 different places to get the correct values.. Like for the 3.9 Ohm resistors I had to get them at Madisound as Parts Express don't carry them.You may also have to use 2 different caps to reach a value like using 2 8 uF caps to reach a 16uF value..The hardest cap to find will be the 21uf so paralleling a 10 and an 11 uf cap maybe required.

New Member here..

New Model 19 owner - xover/foam questions

Quote:

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Originally Posted by Altec Best

Hi Mike,

All the info you need are in these threads.All the info you need should be here, but of course if you have any other questions. I would be happy to answer them..

I would use Solen Fast Caps 250v or 400v are fine..Leave the coils ! They very rarely ever go bad, and is a waste of money IMHO.. The parts you may have to source from 2 different places to get the correct values.. Like for the 3.9 Ohm resistors I had to get them at Madisound as Parts Express don't carry them.You may also have to use 2 different caps to reach a value like using 2 8 uF caps to reach a 16uF value..The hardest cap to find will be the 21uf so paralleling a 10 and an 11 uf cap maybe required.

New Member here..

New Model 19 owner - xover/foam questions

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Okay, thanks for the reply and info. I'd read a couple of posts on a different site saying to avoid the Solens for the 19s as they sounded "gritty", but obviously experiences and opinions vary considerably. Thanks for the tip on Madisound as well.

Mike

Quote:

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Originally Posted by mac24

Okay, thanks for the reply and info. I'd read a couple of posts on a different site saying to avoid the Solens for the 19s as they sounded "gritty", but obviously experiences and opinions vary considerably. Thanks for the tip on Madisound as well.

Mike

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The Solens are fine you can use Daytons as well..They aren't expensive and work well.I also tried Sonicaps they sound good to but are much more expensive then the Solens or Daytons..

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Quote:

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Originally Posted by Altec Best

Hi Mike,

All the info you need are in these threads.All the info you need should be here, but of course if you have any other questions. I would be happy to answer them..

I would use Solen Fast Caps 250v or 400v are fine..Leave the coils ! They very rarely ever go bad, and is a waste of money IMHO.. The parts you may have to source from 2 different places to get the correct values.. Like for the 3.9 Ohm resistors I had to get them at Madisound as Parts Express don't carry them.You may also have to use 2 different caps to reach a value like using 2 8 uF caps to reach a 16uF value..The hardest cap to find will be the 21uf so paralleling a 10 and an 11 uf cap maybe required.

New Member here..

New Model 19 owner - xover/foam questions

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Okay, thanks.

A couple other questions for you then...............is there any benefit / disadvantage to using a 10 and an 11 cap for 21uF, versus using a 20 and a 1 together?

Also, I think I've identified everything I need, but I'm a little stumped as to the L-Pad. The Altec schematic I have lists R1, R3 = 8 ohm L-Pad, but on the drawing it shows
R1=8 ohm and R3 = 35 ohm? Plus, I can't physically find them on the crossover board.
Sorry, probably silly questions but remember..........non-tech here :)

One more question. I'd like to use Mills resistors but they only seem available in a 12w as opposed to the 10w specified by Altec. Is it even possible to use the 12w instead, and if so what would the main difference be ( HF volume etc. ) ?

Thanks for the help and patience,
Mike

No audible difference really in joining the capacitors together to reach the desired capacitance (other than taking up space on the board and a bit more work for your tech!).

The L-Pads are the "dials" on the front of the crossover assembly. Note that those units function in the stock M19 crossover circuit as variable resistors, not true L-Pads.
The schematic is a little misleading. You don't literally need 8-ohm and 35-ohm L-pads. The way that the L-pads work in this circuit is that they are actually both 8-ohm L-Pads, but have their connections "reversed" for the HF vs the MF L-Pad. There are actually two variable resistors within each. One (series) provides up to 8-ohms of resistance, the other (parallel) provides up to ~35 ohms.

These essentially provide user-controlled resistance to help adjust the Mid frequencies and High frequencies for the particular material you're playing, the type of equipment in your system, or the dynamics of the room.

On your last question, higher wattage resistors won't make any difference, they simply have a bit more power-handling before they cook. 12w will be fine in your circuit.

OK Mike answered your questions..Pretty much what i was going to say..But i personally like to keep the values closer together.. When working with 2 similar size caps it is easier to work with than one big one and one tiny one.. A 1uF cap is quite small..Also looks a lot better I think.No sonic difference that i can tell however.The L-pads are those big round things on the back of the black aluminum plate...

These are the L-pads I use https://www.madisoundspeakerstore.co...w-8-ohm-l-pad/.

Quote:

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Originally Posted by Alien_Shore

No audible difference really in joining the capacitors together to reach the desired capacitance (other than taking up space on the board and a bit more work for your tech!).

The L-Pads are the "dials" on the front of the crossover assembly. Note that those units function in the stock M19 crossover circuit as variable resistors, not true L-Pads.
The schematic is a little misleading. You don't literally need 8-ohm and 35-ohm L-pads. The way that the L-pads work in this circuit is that they are actually both 8-ohm L-Pads, but have their connections "reversed" for the HF vs the MF L-Pad. There are actually two variable resistors within each. One (series) provides up to 8-ohms of resistance, the other (parallel) provides up to ~35 ohms.

These essentially provide user-controlled resistance to help adjust the Mid frequencies and High frequencies for the particular material you're playing, the type of equipment in your system, or the dynamics of the room.

On your last question, higher wattage resistors won't make any difference, they simply have a bit more power-handling before they cook. 12w will be fine in your circuit.

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Thanks so much for the reply and the great description. I understand the network a lot better now, thanks. Ordered my caps and resistors today, so I'm looking forward to the rebuild. I'm going with Dayton PCMP 250v caps, and Mills 12w NI Resistors. I'd be happy to post my thoughts on the results when I'm done if anyone is interested?
Thanks again for the advice,
Mike

Of course!
These threads are always much more useful with the follow-through of results once the mods are completed.
Do let us know if you have any other questions or your findings once you're done.

Quote:

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Originally Posted by Alien_Shore

Of course!
These threads are always much more useful with the follow-through of results once the mods are completed.
Do let us know if you have any other questions or your findings once you're done.

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Thanks Allen, I agree. That's why I like these forums. I'll list the rest of my system as well, when I post my initial "post-mod" opinion.

on the ground bypass, all that has to be done is run a wire from lug 1-2 then 2-3 then 3-4? does any other wiring need to be done?