Who designed the original SP-3? I think it is unique and great

[dak]

The question I have is HOW does Peavey get such flat response out of the SP3 ? LOL, the frequency response graph in the Peavey Literature looks almost like a straight line! Very Impressive!

Well, look at this whitepaper, the bottom section about constant directivity horns. The SP3 uses a specific frequency crossover that

• employs the bass speaker as part of the highpass circuitry for the horn driver, resulting in higher steepness at the cost of being specific to one bass speaker
• attenuates the horn response at lower frequencies with a custom autotransformer that is different for every speaker combination/enclosure
• uses components of custom values for every separate speaker model

So there is really no point in, say, replacing the bass speaker with a "better" one. And this is a speaker that is pretty good even off-axis as opposed to speakers with more directive horns.

So the "flat response" is not an accident but a consequence of engineering the frequency crossover to make for such a flat response, including components and a design that is kind of unusual to see in typically more generic crossovers.

[ka7niq]

The question I have is HOW does Peavey get such flat response out of the SP3 ? LOL, the frequency response graph in the Peavey Literature looks almost like a straight line! Very Impressive!

Well, look at this whitepaper, the bottom section about constant directivity horns. The SP3 uses a specific frequency crossover that

• employs the bass speaker as part of the highpass circuitry for the horn driver, resulting in higher steepness at the cost of being specific to one bass speaker
• attenuates the horn response at lower frequencies with a custom autotransformer that is different for every speaker combination/enclosure
• uses components of custom values for every separate speaker model

So there is really no point in, say, replacing the bass speaker with a "better" one. And this is a speaker that is pretty good even off-axis as opposed to speakers with more directive horns.

So the "flat response" is not an accident but a consequence of engineering the frequency crossover to make for such a flat response, including components and a design that is kind of unusual to see in typically more generic crossovers.

What I still dont understand is, how does Peavey get such a nearly ruler flat response out of the SP3, when the Peavey 22A driver in that Horn shows a big broad peak from 2 to 4 K ?
The Peavey SP3 uses the same horn and driver as my speakers, and also crosses over at 800HZ.
Ya think maybe that Peavey is Lying to us about the response of the SP3 ?
If you ever get the chance, look at the Peavey Spec Sheet on a SP3.
It shows nearly ruler flat response, clear out well past 10K!
This has got to be a Lie, because not only does the Peavey 22A driver have a well known broad peak from 2 to 4 K, but it also does not play well out in frequency either!
Yet Peavey shows the SP 3 with nearly ruler flat response, well out to nearly 20K!

Screenshot (6).png (368.71 KiB) Viewed 2458 times

[dak]

So the "flat response" is not an accident but a consequence of engineering the frequency crossover to make for such a flat response, including components and a design that is kind of unusual to see in typically more generic crossovers.

What I still dont understand is, how does Peavey get such a nearly ruler flat response out of the SP3, when the Peavey 22A driver in that Horn shows a big broad peak from 2 to 4 K ?
The Peavey SP3 uses the same horn and driver as my speakers, and also crosses over at 800HZ.

I may not be expressing myself well, so let's try this again: the frequency crossover of the SP3 does not just split the output between different frequencies, it also significantly attenuates the horn driver response (using an autotransformer) where you see that broad peak in its response and then fades out that attenuation as frequencies get higher (bypassing the autotransformer with a capacitor).

The crossover contains elements compensating for the unequal frequency response of the driver/horn combination. I actually have broken down a somewhat similar crossover (1545M) for parts and used it for improving the frequency response of a Leslie clone (after replacing both bass and horn driver), with a few iterations of measuring frequency response (electrically at the individual speakers and acoustically) and working with Spice. You don't really get autotransformers with horn-crossover usefulness at scrapyard prices easily, so I was glad for that expedient.

While I did mess with other parts for reduced noise, the replaced speaker section makes the main difference. I needed this accuracy since we currently employ this for amplifying both a drum computer (well, an arranger keyboard) and an acoustic bass accordion, and the latter specifically has a rather crowded frequency spectrum and easily sounds awful with too much bumpiness in the frequency response.

So Peavey put components (and work) into the crossover for flattening the frequency response of the crossover/driver combination.

[Bartman]

As dak mentioned previously, go read that white paper, the part concerning CD horn EQ. The crossover in the SP3 is doing it's own EQing in order to get that flat response, while a paper showing just the horn response is showing you what happens when you don't have any horn EQ engaged. The CD horn EQ needs to be done either with the speaker's internal crossover circuitry, or done externally by electronics before the signal gets to the amplifier that will be driving the horn (this is part of bi-amping).

[Dookie]

The question I have is HOW does Peavey get such flat response out of the SP3 ? LOL, the frequency response graph in the Peavey Literature looks almost like a straight line! Very Impressive!

Well, look at this whitepaper, the bottom section about constant directivity horns. The SP3 uses a specific frequency crossover that

• employs the bass speaker as part of the highpass circuitry for the horn driver, resulting in higher steepness at the cost of being specific to one bass speaker
• attenuates the horn response at lower frequencies with a custom autotransformer that is different for every speaker combination/enclosure
• uses components of custom values for every separate speaker model

So there is really no point in, say, replacing the bass speaker with a "better" one. And this is a speaker that is pretty good even off-axis as opposed to speakers with more directive horns.

So the "flat response" is not an accident but a consequence of engineering the frequency crossover to make for such a flat response, including components and a design that is kind of unusual to see in typically more generic crossovers.

What I still dont understand is, how does Peavey get such a nearly ruler flat response out of the SP3, when the Peavey 22A driver in that Horn shows a big broad peak from 2 to 4 K ?
The Peavey SP3 uses the same horn and driver as my speakers, and also crosses over at 800HZ.
Ya think maybe that Peavey is Lying to us about the response of the SP3 ?
If you ever get the chance, look at the Peavey Spec Sheet on a SP3.
It shows nearly ruler flat response, clear out well past 10K!
This has got to be a Lie, because not only does the Peavey 22A driver have a well known broad peak from 2 to 4 K, but it also does not play well out in frequency either!
Yet Peavey shows the SP 3 with nearly ruler flat response, well out to nearly 20K!
Screenshot (6).png

In all fairness though I wouldn't call them ruler flat. There is 10 db's per line going left to right in this graph. 10 db's most people feel is twice as loud. To get 10 db's louder a person would have to go from 100 watts to 1000 watts roughly. Point 1 looks to be about 5 db's down with the points between 5000hz and 7000hz or so. Then at 16,000hz it is up 5 db's from that point. 3 db's is a noticeable change. 5 db's should show up in younger peoples hearing range. As a person gets older they don't hear high frequencies. If a person is above 45/50 or so they don't hear much above 8,000hz or so. With a lifetime of loud music some can't hear even those frequencies. If a person around 40 or so says they can hear above 14,000hz or so just smile and walk away Also the 22A back then really didn't go much above 16,000hz. It's easy to see how the response drops out in that graph. Again 10 db's is quite a drop in output. The graph also has no spec's to the measurement type, amount of smoothing/averaging which can make a ok speaker look better than it is. As always it's good to know what the measurements are telling you. Is this on axis or off? If it is on axis what does it look like 45 degrees to the left or right? I started with SP1's many years ago and have had way too many Sp speakers with the 22,22A,22XT,22TI on and on to even begin to recall. Remember the 22 and the crossover in it is designed to work with the CD Horn. With a CD horn the output decreases as the Frequency increases. By design it's mass is just to great to reach the highest of frequencies. I've measured more than a few with Smaart through the years to not know how they perform or sound. I had my Sp1's on Home Stereo Duty back in the mid 1990's and thought they sounded fine for what they are. Time does march on though. Doug

[Dookie]

The question I have is HOW does Peavey get such flat response out of the SP3 ? LOL, the frequency response graph in the Peavey Literature looks almost like a straight line! Very Impressive!

Well, look at this whitepaper, the bottom section about constant directivity horns. The SP3 uses a specific frequency crossover that

• employs the bass speaker as part of the highpass circuitry for the horn driver, resulting in higher steepness at the cost of being specific to one bass speaker
• attenuates the horn response at lower frequencies with a custom autotransformer that is different for every speaker combination/enclosure
• uses components of custom values for every separate speaker model

So there is really no point in, say, replacing the bass speaker with a "better" one. And this is a speaker that is pretty good even off-axis as opposed to speakers with more directive horns.

So the "flat response" is not an accident but a consequence of engineering the frequency crossover to make for such a flat response, including components and a design that is kind of unusual to see in typically more generic crossovers.

What I still dont understand is, how does Peavey get such a nearly ruler flat response out of the SP3, when the Peavey 22A driver in that Horn shows a big broad peak from 2 to 4 K ?
The Peavey SP3 uses the same horn and driver as my speakers, and also crosses over at 800HZ.
Ya think maybe that Peavey is Lying to us about the response of the SP3 ?
If you ever get the chance, look at the Peavey Spec Sheet on a SP3.
It shows nearly ruler flat response, clear out well past 10K!
This has got to be a Lie, because not only does the Peavey 22A driver have a well known broad peak from 2 to 4 K, but it also does not play well out in frequency either!
Yet Peavey shows the SP 3 with nearly ruler flat response, well out to nearly 20K!
Screenshot (6).png

Thought I'd give a better example. Here is a Peavey SP2G. As you can see there is 10 db's per line. Point 1 is 10,000hz and Point 2 is 20,000hz. It's easy to see the difference between 10,000 and 20,000 hz is around 14 db's. Also looking through the entire frequency range of the speaker you can see peaks and dips in that 10 db window. This is not all that bad for a high output PA speaker and is more realistic with the 22 driver used. Just food for thought. Doug

https://assets.peavey.com/literature/ma ... 300313.pdf

[dak]

Well, with the SP2G frequency response one sees the "horn EQ" pretty well: the high frequency gain with a simple analog circuit cannot really be lower than 6dB/octave and the horn losses at high frequencies are smaller than the compensation. Newer horn shapes and drivers make for more even response even with larger horizontal fanout of directivity at higher frequencies. For open-air, one can also compensate by making the vertical directivity fit the desired frequency response (basically wasting more sound on the birds at lower frequencies), leaving less work for the frequency crossover. But in a closed room, that strategy gives mixed success.

But at any rate, the measurement situation is typically just on-axis and open-air and not necessarily representative of the average use case for the audience. You have to hear it.

[Dookie]

Well, with the SP2G frequency response one sees the "horn EQ" pretty well: the high frequency gain with a simple analog circuit cannot really be lower than 6dB/octave and the horn losses at high frequencies are smaller than the compensation. Newer horn shapes and drivers make for more even response even with larger horizontal fanout of directivity at higher frequencies. For open-air, one can also compensate by making the vertical directivity fit the desired frequency response (basically wasting more sound on the birds at lower frequencies), leaving less work for the frequency crossover. But in a closed room, that strategy gives mixed success.

But at any rate, the measurement situation is typically just on-axis and open-air and not necessarily representative of the average use case for the audience. You have to hear it.

The passive crossover network turns down the lower range of the horn to compensate for the loss of higher frequencies to get a flatter response. Because of the CD horn "Lens" design, in these older horns we are talking about, as the frequencies go up its output goes down because of the spreading out of the higher frequencies the lens does. They lower the frequency output level of the lower frequencies the horn operates in to account for it. The Horn driver is around 10 db's louder than the woofer in many cases so they can use a pad to get the horn output a little more even. This is a compromise. These older first-generation lenses are what they are. The crossover for the horn/horn lenses compensation in them is pretty basic by today's standards. We are talking about an over 40-year-old design. I owned one of the first generation SP1's just a couple of years after they came out and many models of the CD horns on up so yeah, I've heard and measured them. I'm not knocking the CD horn or it's response but one has to have realistic expectations of these first generation horns we are talking about. Certainly if the internal passive crossovers are used.
https://peavey.com/c/Horn-Equalization