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NotThisChris

Altec 511b inside of a Cornwall.

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3 hours ago, moray james said:

crossover point is not the issue the slope is the issue (not saying it is the best point but it's not a bad choice for your driver). Trouble is that at 1800 Hz. your woofer output is only 6 db down in level from the xover point of 900Hz., at 3600Hz it is only 12 db down do you think you really want o be listening to this? along with the scattered dispersion from such a large woofer with waves that cancel and those which couple you are going to have a loudspeaker which will not disappear. Using an active xover will let you easily find the best crossover point and slope as well as the   crossover filter type, you will need four channels of amplification and it does not matter if they are SS or tube matching gain of all the channels is a good idea which is why I suggested two stereo block amps same brand/model will work well. You should be able to come up with a nice two way, I like two ways have fun. I hope this helps.

Thank you for your wisdom sir. I found a crossover that may do the trick locally, a dbx233s for 50 bucks. I have a pair of tube amps that I wouldn’t mind using for the task as well. Gain may be a problem but I’m patient with tuning stuff.  I will post again when I get the set up working. 

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8 hours ago, NotThisChris said:

The project is done, sort of.  I’m having issues with balance due to the Lpads I purchased not being matched. I need to see if I can take it apart to make it work. 

A08CD2E3-2427-4520-9AD2-B9D40020B7DE.thumb.jpeg.f2332cdf38d00013cf5451886b988447.jpeg
 

you have to work on the rear area to close it off ,  for leaks in the cabinets - , a small wooden box  that is sealed over the mids drivers should be better that this picture -

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6 hours ago, NotThisChris said:

Thank you for your wisdom sir. I found a crossover that may do the trick locally, a dbx233s for 50 bucks. I have a pair of tube amps that I wouldn’t mind using for the task as well. Gain may be a problem but I’m patient with tuning stuff.  I will post again when I get the set up working. 

if your amps are stereo blocks then simply use one stereo block per speaker, right channel woofer left channel tweeter problem solved (vertical biamping) adjust any left to right speaker output level difference with the active xover. done.

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3 hours ago, moray james said:

if your amps are stereo blocks then simply use one stereo block per speaker, right channel woofer left channel tweeter problem solved adjust any left to right output level difference with the active xover. done.


Actually I intend to use a separate amp for lows and highs. I think I can do that with this.  I don’t have enough TRS to RCA connectors so I need to buy more tomorrow. Just running one speaker, some observations:

1. Transparency is present now. 
2. The crossover sounds much better at 700 hz. 
3. Taking the Highs down 10 dB balances everything very well. A click Less or more and the sound goes out the window.  Go figure, one is roughly 10db more sensitive. 

 

I probably would have given up if I stayed passive. Thanks for everyone’s suggestions to go active. I need to acquire wood at some point to finish the rear of the cabinets. 

 

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by using a stereo amp for each speaker the gain of the amp driving the woofer and the tweeter of each speaker matches. By all means do what ever you like this is a learning experience.

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An update! I found a pair of Turbosound LS-1506 15” woofers, apparently equivalent to a precision device woofer of some kind. Anyone heard of turbosound? They were free, for the most part. They are humongous, cast aluminum frame, and sound pretty damn good. 
 

The crossover sounds nice as configured. I plan to address the amplifier issue at sone point. This was just a luck find. 

D22C3191-84E5-49C8-93B7-65F9FC4D30D9.jpeg

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9 minutes ago, NotThisChris said:

An update! I found a pair of Turbosound LS-1506 15” woofers, apparently equivalent to a precision device woofer of some kind. Anyone heard of turbosound? They were free, for the most part. They are humongous, cast aluminum frame, and sound pretty damn good. 
 

The crossover sounds nice as configured. I plan to address the amplifier issue at sone point. This was just a luck find. 

D22C3191-84E5-49C8-93B7-65F9FC4D30D9.jpeg

good find -----------

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Posted (edited)

After an hour or two of listening and tweaking I can say with confidence that these woofers are some capable pieces of equipment. AB’ing the woofers alone, They are flatter in response, balanced but powerful. I guess cohesion comes to mind with the horns. Only negative is my Cornwalls now weigh 100 pounds+.  I’m a bit tired now but here are some more photos of the project as it’s taking shape and form. 40645C3E-0FA4-4F43-9114-E39E7830F39E.thumb.jpeg.cc3c153dd57b86e840d7082c707de255.jpeg3A621355-6B0E-482F-8792-D8AC93574E3B.thumb.jpeg.a368150e0fee0762d60a5ecfdba4de68.jpeg

Edited by NotThisChris
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On 5/19/2020 at 7:22 PM, RANDYH said:

you have to work on the rear area to close it off ,  for leaks in the cabinets - , a small wooden box  that is sealed over the mids drivers should be better that this picture -

 

I agree with Randy on this. Even though the cabinet is ported, you don't want any air leaks around the compression drivers. I can't tell how far they protrude, but a piece of 3/4 inch ply with a cut out and then another piece to cover it would be fine and not hard to make.

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7 hours ago, NotThisChris said:

Only negative is my Cornwalls now weigh 100 pounds+.

 

Original La Scalas were approx. 125 lbs. Mine are up from that as I did some other work on them. My MWM cabinets are around 288 lbs. each. I don't move them much. 😉

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9 hours ago, Marvel said:

 

I agree with Randy on this. Even though the cabinet is ported, you don't want any air leaks around the compression drivers. I can't tell how far they protrude, but a piece of 3/4 inch ply with a cut out and then another piece to cover it would be fine and not hard to make.

I could honestly take an inch ply and hollow it out a bit. It’s only about 1/4 inch protruding. It will happen after I finish stuffing the cabinet walls with damping material. 
 

To touch up on your weight comment, I had a pair of klipschorns and La Scalas at some point. It’s just odd with a Cornwall.

 

So, all seriousness aside, Cornwaltecs or Voice of the Corn? 😃
 

 

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33 minutes ago, NotThisChris said:

 It will happen after I finish stuffing the cabinet walls with damping material.
 

 

make sure you leave a large open volume of air inside the cabinet which directly couples the vent to the woofer, this volume of air is necessary and it must be open and free to resonate as it is this resonant energy of the air which lets the woofer drive the vent into sympathetic reflex action. If you were to fully stuff the cabinet the reflex action would diminish dramatically and you would lose bass weight.

Back in the seventies I had a pair of Altec A7-800 and I really wanted to switch up to the 511b horn but just did not have the funds to cover the expense of all the components necessary. I had spent some time listening to the 511b and much preferred it to the 811b. That was a long time ago and today's modern horns are so much better in every way.

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1 hour ago, moray james said:

make sure you leave a large open volume of air inside the cabinet which directly couples the vent to the woofer, this volume of air is necessary and it must be open and free to resonate as it is this resonant energy of the air which lets the woofer drive the vent into sympathetic reflex action. If you were to fully stuff the cabinet the reflex action would diminish dramatically and you would lose bass weight.

Back in the seventies I had a pair of Altec A7-800 and I really wanted to switch up to the 511b horn but just did not have the funds to cover the expense of all the components necessary. I had spent some time listening to the 511b and much preferred it to the 811b. That was a long time ago and today's modern horns are so much better in every way.

Thanks for the tips. My friend gives me shredded denim pads that his food service uses to insulate food. It does pretty well for the walls, which I intend it to go. Only the walls though. I say stuff but a better term is probably lined. 
 

I actually had no desire for altec anything. I got them as a package deal, the gentleman previous had them on top, which seems like a sensible idea. I am not sensible however, and always wanted a two way speaker. I’ve come to love klipsch through my desire to build tube amplifiers, which sound lovely with klipsch heritage stuff. Really cool on the A7’s though!

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On 5/22/2020 at 4:16 PM, NotThisChris said:

So, all seriousness aside, Cornwaltecs or Voice of the Corn? 😃

 

Ultra-Crites

 

DSCN3437.thumb.JPG.44b70a7629cccf09b046847f3de52eec.JPG

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Posted (edited)

So, out of curiosity, does anyone have any experience with time alignment? A crossover that I found for sale has the ability to time delay a specific speaker. Is it futile without equipment to measure results or can I adjust by ear? 
 

Ultra-Crites. Yeah. Gonna need. A sponsorship for that one. All jokes aside, I did just buy some 3636 autoformers from him. I’m not sure he would want his name on these... things.  😄

 

Besides, my friend already named them Cornhorns. 🙃 I’m getting it engraved in brass. 

Edited by NotThisChris

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1 hour ago, mike stehr said:

 

Ultra-Crites

 

DSCN3437.thumb.JPG.44b70a7629cccf09b046847f3de52eec.JPG

 

In '04  I had the 511b and 902 driver perched on top.  Baby-cheeks tweet.   Called them  Alcorns. 

My wife was out of town came back the next day.  She asked " What have you done to my walnut speakers"?  

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2 hours ago, mike stehr said:

 

Ultra-Crites

 

the paint job looks fantastic , evel looks piano black , can you please share what paint was used to achieve this---shiny  result

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47 minutes ago, IB Slammin said:

 

In '04  I had the 511b and 902 driver perched on top.  Baby-cheeks tweet.   Called them  Alcorns. 

My wife was out of town came back the next day.  She asked " What have you done to my walnut speakers"?  

yeah -  like ooooops

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10 hours ago, mike stehr said:

 

Ultra-Crites

 

DSCN3437.thumb.JPG.44b70a7629cccf09b046847f3de52eec.JPG

 

7 hours ago, RANDYH said:

the paint job looks fantastic , evel looks piano black , can you please share what paint was used to achieve this---shiny  result

 

Yes, I’d really like to know too!!!

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