Autoformer Attenuation

[Deang]

I tried this a couple of months ago in the technical section, but got a limited response.

We have all of these various horn and driver combinations out there now, and because of this crossover thing I do, I'm really curious about where folks are dialing their drivers back in at.

So far, with the 2" drivers and the horns that are available for them, I don't see anyone attenuating more than 13dB, and everyone I know about right now is either at -12, -12.5, or -13dB.

Is there anything that anyone wants me to know, or are those numbers pretty much the same for everyone?

The tweeters are piling up too. Any data for those would be greatly appreciated as well.

[DrWho]

I think it would really depend on the style of horn....constant directivity versus collapsing polars can be a good 10-16dB different when comparing at 20kHz.

I wonder if resistors or the autoformer would be lower distortion....temperature hysteresis x temp co versus magnetic hysteresis.....I'd probably go with the autoformer for people with tube amps.

I'm kinda surprised I don't see anyone putting heatsinks on their resistive pads and/or going to crazy temp co parts. You can measure the distortion with line level signals and that's with only 100mW of dissipation...

[jcmusic]

Dean I am using the 2" V-Trac's from Volti Audio with BMS 4592 ND-Mid Drivers and an upgrades version of AL's Universal A xovers, I am at -10db on the mid drivers...

[Sprinter1104]

Dean- Like Canyonman, I'm using V-trac's with the BMS 4592 NC-Mid with Al's Universal Kit. I'm at -12.5db on the mid drivers.

[Deang]

Thanks Jay, that's helpful actually. So far, you're the only person that's not attenuating more than that. But then, you're networks are a little different than what most are using.

Mike, by the time an autoformer starts to saturate, you're going to be deaf. If you haven't already, read PK's "The Problem with Attenuators". Roy mentioned the problems associated with phase, but I believe an autoformer will have considerably less distortion than an L-pad.

I'm always surprised by the lack of participation in these poll type threads. C'mon folks, work with me here.

[Cut-Throat]

Dean....I know what you mean.....I get very little participation when I asked about Bi-amping.

To answer your question....With my 1.4 inch Drivers and Altec Horns, I am -12db down......But you probably knew that, as you helped me build them.

[Shakeydeal]

Al set my xovers for 6db of attenuation on the mid. Bobs are set at -9. It seems as though everyone is doing way more than that. I will spend the long weekend experimenting.

Shakey

[Deang]

It depends on your setup. The guys who responded first are using 2" exit drivers with sensitivity ratings substantially higher than the K-55. What are you running speaker wise?

[Deang]

I'm real sorry about that incident with the bi-amping question Kevin, that was not my finest moment. To be honest, I wasn't quite sure how to answer since you were splitting the network and doing a hybrid application. I didn't even fully understand until I saw your posts in the bi-amp/active thread. I'm not always as sharp as some think I am, and it really doesn't take much to get me out of my comfort zone.

Okay, another -12dB

What I want to know is how you guys are getting -12.5dB with Al's networks. All of the charts I have for the 3619 (when the swamping resistor is used), shows -12dB and then the next increment is -13.7dB.

[mboxler]

This is from ALK's "Universal upgrade" in his download section...

Taps -db

x-1 -22.7

1-2 -19.7

2-3 -16.7

0-x -15.0

2-3 -13.7

0-1 -12.0

x-3 -9.8

0-2 -9.0

1-4 -6.8

0-3 -6.0

x-4 -5.5

2-5 -3.8

0-4 -3.0

1-5 -2.5

x-5 -1.7

Mike

[Deang]

Thanks. Yep, same one I have. Time to call Al!

Those of you with newer networks are getting 3619-ET units and the networks have been rewired in such a way to allow for 1dB increments. I just did the same with the Super AA network - so no more gaps in attenuation. Still, you get -12dB or -13dB, there is no -12.5 with either autoformer or wiring configuration. I'm sooo confused. I'm also trapped in my car with just my phone and a bad memory!

[jcmusic]

Dean, Thanks Jay, that's helpful actually. So far, you're the only person that's not attenuating more than that. But then, you're networks are a little different than what most are using.

Exactly and it might be the huge inductor coils I am using making that difference plus I am using a different autoformer, also when I was using Al's Universal I too was attenuating to -12.5db. However when I went to the new xovers I started at -12db and quickly realized I needed to go to -11db, after a little while I move to -10db and found this is exactly where I need to be. I will not change from here, Dean the paperwork I got with my Universal's has it as -12.5 and that came from Al himself.

[Shakeydeal]

It depends on your setup. The guys who responded first are using 2" exit drivers with sensitivity ratings substantially higher than the K-55. What are you running speaker wise?

Bob's stock C cornscala with selenium drivers.

[Cut-Throat]

I'm real sorry about that incident with the bi-amping question Kevin, that was not my finest moment. To be honest, I wasn't quite sure how to answer since you were splitting the network and doing a hybrid application. I didn't even fully understand until I saw your posts in the bi-amp/active thread. I'm not always as sharp as some think I am, and it really doesn't take much to get me out of my comfort zone.

Okay, another -12dB

What I want to know is how you guys are getting -12.5dB with Al's networks. All of the charts I have for the 3619 (when the swamping resistor is used), shows -12dB and then the next increment is -13.7dB.

All forgiven no problem....I am bi-amping now and it is the biggest single improvement that I have made to my system since I swapped out the midrange horns. I've got 800 watts per chanel on the Bass bins now with a whopping 1.8 watts per channel on the mids and tweeters.

I will probably be getting some different horns in the near future...Maybe Oris and they include the passive crossover with them. I am using Hypex Plate Amps on the Bass Bins that have an active crossover built into them. I might understand them in a few years.

Edited November 27, 2013 by Cut-Throat

[muel]

Gee whiz you're impatient, Dean!

I've settled at 12 in my setup and haven't moved it since.

Nice Jupiter caps in your avatar! On what network have you installed them? I priced these a long time ago and it was pretty steep!

[Deang]

Al set my xovers for 6db of attenuation on the mid. Bobs are set at -9. It seems as though everyone is doing way more than that. I will spend the long weekend experimenting.

Shakey

The Selenium D405 has a sensitivity of 110dB (on a horn, but I don't know which one). So -9dB seems appropriate.

I guess you have CornScala-walls? The -6dB isn't right, unless of course it sounds right and you like it. How long ago did you purchase these - do they use the new 3619-ET? If so, the red wire plugs into the input tap labeled -0 and the other wire should be plugged into the tap output labeled 9.

[Deang]

Gee whiz you're impatient, Dean!

I've settled at 12 in my setup and haven't moved it since.

Nice Jupiter caps in your avatar! On what network have you installed them? I priced these a long time ago and it was pretty steep!

I have no patience, you should know that by now!

I'm not ready to talk about the Jupiters here, not yet. I'll post impressions within the next month on my business Facebook Page, as well as the details surrounding what I'm going to be doing with the first $1200 order being shipped to me on Monday.

Edited November 27, 2013 by DeanG

[Shakeydeal]

Al set my xovers for 6db of attenuation on the mid. Bobs are set at -9. It seems as though everyone is doing way more than that. I will spend the long weekend experimenting.

Shakey

The Selenium D405 has a sensitivity of 110dB (on a horn, but I don't know which one). So -9dB seems appropriate.

I guess you have CornScala-walls? The -6dB isn't right, unless of course it sounds right and you like it. How long ago did you purchase these - do they use the new 3619-ET? If so, the red wire plugs into the input tap labeled -0 and the other wire should be plugged into the tap output labeled 9.

These are brand new, just received them Monday. I haven't even installed them yet, hopefully tonight. Yes, they are cornscala-walls.

Shakey

[Schu]

Gee whiz you're impatient, Dean!

I've settled at 12 in my setup and haven't moved it since.

Nice Jupiter caps in your avatar! On what network have you installed them? I priced these a long time ago and it was pretty steep!

I'll show you pictures of them when they come in

Edited November 27, 2013 by Schu

[ClaudeJ1]

I think it would really depend on the style of horn....constant directivity versus collapsing polars can be a good 10-16dB different when comparing at 20kHz.

I wonder if resistors or the autoformer would be lower distortion....temperature hysteresis x temp co versus magnetic hysteresis.....I'd probably go with the autoformer for people with tube amps.

I'm kinda surprised I don't see anyone putting heatsinks on their resistive pads and/or going to crazy temp co parts. You can measure the distortion with line level signals and that's with only 100mW of dissipation...

Well, when I measure an 85 db average level at my sweet spot (where A/V receivers calibrate and, co-incidentally my listening level), my mid horns only draw about 10 milliwatts, so I'm 10 db below that. Besides, since I "gain matched" my drivers I only use one cap and no resistors or autoformers in the signal path. I guess you might say it's not part of my listening or design equation.