Using Altec 30904 atteuator with 511/416

srm51555

AK Subscriber
Subscriber
Hello,

Has anyone tried using the 30904 with a 511 horn, 807 drivers and a 416 woofer? The crossover is a N501. I built a pair of speakers with these and it's seems as if the midrange needs to be tamed. I have read that the 30904 was only used for the 411 woofer,but I thought about just building the HF part to solve my problem. I have never built anything from scratch like this before and all suggestions will be greatly appreciated.

Thanks, Scott
 
30923 is the HF section only version.

Use 4-Ohm resistors in lieu of 3.9 Ohms.

6.2 uF is fine instead of 6.0 uF, or use two 3.0 uF in parallel.

You can vary R-2 to alter the amount of compensation.

Yes, you need it.... :yes:

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Hello,

Has anyone tried using the 30904 with a 511 horn, 807 drivers and a 416 woofer? The crossover is a N501. I built a pair of speakers with these and it's seems as if the midrange needs to be tamed. I have read that the 30904 was only used for the 411 woofer,but I thought about just building the HF part to solve my problem. I have never built anything from scratch like this before and all suggestions will be greatly appreciated.

Thanks, Scott


I use the network, listen to it every day. It works well and improves the highs and overall tonal balance. I use only the high frequency section of the network.
 
Only thing i'd add is that using the EQ/attenuator with the 416/807 combo might run you into power limitations on the 807 depending on your listening habits/preferences.

Do the 807's still have the symbiotik diaphragms in them?
 
Are the components the same if used with 16 ohm drivers?
I don't think so.

Might be as simple as multiplying or dividing values by a factor of two.

Pinging our resident network experts on this one...................Zilch, TB, anybody?
 
I was thinking 1/2 * C. and 2 * R . Then I looked at some of Jeff M.'s crossovers and am more confused as this part of his circuits are similar
for 8 and 16 ohm.

Bryan
 
Are the components the same if used with 16 ohm drivers?
DRAT! I knew last night somebody would ask.

I'll look at it in SPICE for a definitive answer.... :yes:

Edit: Green is 30923 with 8-Ohm resistive load, and yellow is 16 Ohms.

It works the same, but with 2 dB less attenuation. There may be impedance implications for your primary filter, though.

For the same contour at 16 Ohms, it's C1 = 3 uF, R-1 = 7.8 Ohms and R-2 = 13 Ohms.

Stock resistor values R-1 = 7.5 Ohms and R-2 = 12.5 Ohms generates the cyan curve using 3.0 uF C-1.

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Again, varying R-2 alters the amount of compensation:

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Zilch, Thank you for the info. It's just what I needed to try to tame these horns. Is using the 30923 similar to what Altec was doing on my 19's except with out the controls?

Bowtie427ss, the 807's still have the symbiotik diaphragms in them. I also tried using the 806's (16 ohm) bi-amped but it still wasn't the sound I was looking for. The speakers will be played with mostly classical at low and moderate volumes, I'll save the rock for the 19's. Thanks again
 
Ok lets see if I understand this fully.
A lower value for R-2 = more compensation = less output to HF driver but a
flatter response?

Bryan
 
Ok lets see if I understand this fully.
A lower value for R-2 = more compensation = less output to HF driver but a
flatter response?
Yes. Less mid-frequency output to the driver, but the high-frequency remains the same. That's how midband attenuation is use to flatten the response.

For it to work, you need headroom, i.e., differential sensitivity between the woofer and the HF driver/horn combination. Generally speaking, there's usually enough available to accomplish some amount of response leveling, even with 806/807 drivers and efficient horn LF.

Appreciate, however, that if the LF is 98 dB, and the HF is 101 dB, there's not much to be achieved with this approach. Sub BMS drivers having at least 110 dB sensitivity, and there's plenty of headroom to work with, but they won't play very well down at 500 Hz.

I've never looked at the larger format versions, which may be another possibility for Srm51555.... :dunno:

Bowtie427ss, the 807's still have the symbiotik diaphragms in them. I also tried using the 806's (16 ohm) bi-amped but it still wasn't the sound I was looking for.
Did your active crossover have built-in CD compensation? Did you try using that?
 
That helps,thanks Zilch.Looks easy and cheap enough to try.
I'm pleased that some guys are getting this.

Many vintage Altec enthusiasts seem to be in denial regarding the inherent deficiencies of their systems in home use, even though Altec themselves ultimately recognized these and provided means to correct them. :dunno:
 
Zilch, the crossover used doesn't have any cd compensation. What do you mean when you say a larger format version? Thanks again for all of you help this prolem in these speakers has been haunting me for years.
 
Zilch, the crossover used doesn't have any cd compensation. What do you mean when you say a larger format version? Thanks again for all of you help this prolem in these speakers has been haunting me for years.
I assume 500 Hz capability matters to you. Go to the BMS site and look up the specs of their 1.4", 1.5", and 2" drivers. 511E horns are 1.4", as I recall, but they are merely 511s with the throat lopped off at the appropriate diameter and a mounting flange added, which any competent machine shop can do.

The most direct solution to your problem is an active crossover with CD compensation like Behringer CX3400, ~$150 complete with cables at Guitar Center or similar source. AK members have been securing them there for $99 for the unit itself lately....
 
I'm pleased that some guys are getting this.

Many vintage Altec enthusiasts seem to be in denial regarding the inherent deficiencies of their systems in home use, even though Altec themselves ultimately recognized these and provided means to correct them. :dunno:


Denial? Many users of old Altecs know perfectly well what their shortcomings are and like them regardless. That's not denial that's satisfaction. And Altec fans have been fiddling with (and then often discarding) compensation networks for many years.

Now I like the extended highs and lows of the later model 19 but on the other hand I'd rather listen to my old AS-21s, warts and all, then most other speakers which have "improved" specs. There's much to be said for relaxing and enjoying something you consider good regardless of it's shortcomings. You know, like with people.
 
Thanks again for all of you help this problem in these speakers has been haunting me for years.
I don't know that any of these suggestions will resolve it for you, but at least you are now aware that the problem is real, and that there are options available to try. :yes:

I don't know who I'd be more pissed at -- the marketeers playin' fast and loose with the specs, or the "Ignore the numbers, trust your EARS, it's the MUSIC, stupid" subjectivists perpetuating the myth

After 40 years of listening to Valencias. and trusting the marketing pitch of how great they are, I am pissed at myself for falling for all the BS.

There's much to be said for relaxing and enjoying something you consider good regardless of it's shortcomings. You know, like with people.
People are rather more of a challenge, Tom.... ;)
 
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