Rebuilding Four SP-2 Cabinets

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Wooferhound
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Rebuilding Four SP-2 Cabinets

Post by Wooferhound » Wed Oct 28, 2020 12:23 pm

I have just rebuilt 4 Peavey SP-2 cabinets. A club was going out of business and gave me a vanload of blown up Peavey gear and these 4 cabinets were part of the booty

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I always change out the jacks on the back panel from the old 1/4 inch to the newer Speakon twist lock connectors, these are all Combo connectors, so 1/4 inch plugs will also work in there.

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It is a big project to change out these jacks that are soldered to the crossover, here are the steps....
- Remove crossover from the backplate
- Punch larger holes in the backplate for the Speakons
- Mount the new Speakon connectors
- Use blowtorch to unsolder and remove all 1/4 connectors from crossover
- Resolder the connections broken by removing the switched bi-amp jacks
- Add wiring for Full Range input from Speakon connectors
- Remount crossover in a new location away from the backplate
- Solder wiring between Speakon connectors and crossover
- Glue metal over the unused holes leftover from the 1/4 inch connectors
The cabinet can No Longer be bi-amped and is now permanently Full Range

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These 2 cabinets were originally SP-2 Ti. One of the 1505-8KADT woofers needed a new basket. One of the Horns had a working RX22 driver on it so I changed the other blown driver to RX22 so the drivers have a slight upgrade. They ended up looking and sounding very nice.

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A week later I rebuilt 2 more newer versions of the SP-2 Cabinets. Did all of that ugly crossover work and changed out the connectors. Both had working woofers and blown 22-XT diaphragms. Fixed the Horn Drivers and spray painted it all new again.

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The backplates claim they were originally SP-2G and SP-5XT but they seem to have been reworked a lot over time and don't have the original components, but they ended up sounding Great. These can't be bi-amped again either and are just Full Range.

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I took all of the Woofers apart to check them, and all of them had the Foam Disk floating in there behind the center Dome.
----- W o o f e r h o u n d -----

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Re: Rebuilding Four SP-2 Cabinets

Post by Dookie » Wed Nov 04, 2020 1:03 pm

The Bottom set of speakers in your post are SP2X's. Both crossovers came from different boxes that are in them now. The Sp5 crossover was setup for a much smaller horn and possibly a higher crossover point so the horns would sound "slightly" different. I had a set of the SP2X's that I rebuilt maybe 7 years ago or so and liked them although heavy. I'd find a matching SP2G or SP2X crossover to get them as close as possible sound wise.

Doug
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Dano0369
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Re: Rebuilding Four SP-2 Cabinets

Post by Dano0369 » Fri Nov 06, 2020 2:36 pm

Looks Good Tim, I started on a set of sp 2 xt today. I need to call roger and check the numbers. By my count they are early 80's but have '79 dates on them . :arrow:
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Re: Rebuilding Four SP-2 Cabinets

Post by Dookie » Sat Nov 07, 2020 7:53 am

Dano0369 wrote:
Fri Nov 06, 2020 2:36 pm
Looks Good Tim, I started on a set of sp 2 xt today. I need to call roger and check the numbers. By my count they are early 80's but have '79 dates on them . :arrow:
Dano. SP2A's came out around 1989 or so. My first Peavey speakers. After them came SP2TI's that ran for a few years. The SP2Ti's were the last in the Sp2 series that had the "Baby Butt" rounded horn len. Guessing 1993 or so they stopped. The SP2 XT's came out after that so they should be around 1993 to 1996 or so and they were the first Sp2's that had a flat horn lens. Then came the SP2G's and later the SP2X. Last is the newer SP2 with nothing after it. I had a set of all of them other than the newest ones. EDIT I do remember one other style of SP2's that were really ugly to me with odd shaped grill and plastic ports. The model number escapes me.
Doug

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Re: Rebuilding Four SP-2 Cabinets

Post by Wooferhound » Mon Nov 09, 2020 9:37 am

I will use the matched SP-2Ti cabinets for smaller sound systems, or as part of a large system as Side Fill monitors or Near Field speakers on the Mains.
The 2 unmatched speakers would be best for for stage monitors for the drums or bass guitar. Could also be used as Delay speakers on the mains
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Re: Rebuilding Four SP-2 Cabinets

Post by netrecce » Wed Nov 11, 2020 11:43 pm

Good job on the Restorations!

On the 2nd set of "unmatched" newer speakers, the "rounded" horn is old and not a Constant Directivity (CD) design. I'd try to replace it with one that matches the angular horn in the other cabinet.

..

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Re: Rebuilding Four SP-2 Cabinets

Post by Dookie » Thu Nov 12, 2020 4:30 am

netrecce wrote:
Wed Nov 11, 2020 11:43 pm
Good job on the Restorations!

On the 2nd set of "unmatched" newer speakers, the "rounded" horn is old and not a Constant Directivity (CD) design. I'd try to replace it with one that matches the angular horn in the other cabinet.

..
The "Rounded Horn Lens" is a CD horn and does require CD horn eq in a active or passive crossover. When these types of horns where used in a Bi Amp setup using the PL type crossover cans often the PL800eq was used. Later to increase power handling the crossover point was raised to 1200hz.

https://reverb.com/item/2143837-peavey- ... etwork-new

https://reverb.com/au/item/2143867-peav ... er-network

I remember well talking to Marty McCann , the head of Peavey's sound division when they had Sound Reinforcement events, about CD horn eq in those speakers horn lenses around 1990 or so. CD horn eq came out with the SP series and others. Even the first SP1 needed CD horn eq in their large horns.

Doug

EDIT: I wanted to add in the first big SP1 speakers the crossover point was 500hz. To get the required CD horn eq for 500hz and above you'd go into the Full Range input with a PL500 can or a active crossover to use the Passive CD horn eq built into the passive crossover. 500hz and below you'd go into the Bi Amp Low jack. Later on it was deemed ok to use the PL800eq with them as the sound quality out weighted the slightly high crossover point for the 15 folded horn so the biamp high/low jacks were used. There was also available a SP-1 PL Crossover can at some point. I honestly don't remember which came out first.
Last edited by Dookie on Thu Nov 12, 2020 7:19 am, edited 2 times in total.

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Re: Rebuilding Four SP-2 Cabinets

Post by Dookie » Thu Nov 12, 2020 4:51 am

netrecce wrote:
Wed Nov 11, 2020 11:43 pm
Good job on the Restorations!

On the 2nd set of "unmatched" newer speakers, the "rounded" horn is old and not a Constant Directivity (CD) design. I'd try to replace it with one that matches the angular horn in the other cabinet.

..
Found this.


Marty McCann:
In answer to the question regard CD horns, here is some history:

Before the Constant Directivity horn was introduced our choices were Lenses, Multi-cell, or Exponential Radial Horns. The CD Horns are described as Multi-Taper and Multi-Flare, due to different rates of expansion from the throat entry to the mouth. There are portions of them that are straight, while other sections resemble conical segments, but with a rough averaging, they can appear close to the Exponential.

F.Y.I., Yes EV did patent the very first CD Horns designed by their engineers Don Keel and John Gilliom. However after months of staying up all night in Buchanan Michigan in the mid 70's using a very slow modem to have a computer on campus at Purdue University crunch the numbers for them, Don and John submitted their design to the management at EV. At that time in the History of Audio, EV was owned by the giant conglomerate Gulton. Management essentially told the engineers that they did good in coming up with this revolutionary design, but that they currently had more orders than they could fill for existing horns and drivers (and after all the tooling and fixtures for current (at the time) models were already amortized (or already paid for). You see the corporate sugar daddies at Gulton did not want to pay for the necessary tooling. CD horns could not be produced with simple blow-molds (like some previous horn models). The mutli-flares and multi-tapers require hard-tooling from a tool and die shop, which cost beau coup $$$'s. Esentially the engineers were told that they did good and that EV would file the patent, but management did NOT want to spend the money for the tooling at that time. The were told to go back to the lab and design other products that would NOT take expensive tooling.

I always had a problem with a form of Dyslexia when it came to that corporate conglomerate's spelling; I always wanted to put the L before the U.

Now I don't know how you would feel if you were told this, but what happened next was probably very good for our industry. Don Keel resigned from EV and went to Altec/Lansing as an independent consultant and designed for them their first CD horn now known as the Mantra-Ray. Of course it was very large, as Altec at the time was doing a lot of stadium installations and they wanted better control in the vertical plane than conventional CD horns. Conventional CD horns are notoriously nearly Cardioid in the vertical plane within the first couple of octaves above the loading cutoff frequency.

Don Keel subsequently went (as a consultant) to JBL and designed their first CD Horns.

In the mean time John Gilliom called Hartley Peavey in Meridian Mississippi, and told HP that since he coauthored the original patents with Don Keel for Electro-Voice, that he knew how to design a CD Horn that would NOT infringe upon the EV patent. So John Gilliom and Peavey formed a relationship. John came up with a completely new CD horn design, as well as a compression driver to compliment the horn (the first Model 22 driver). Hartley Peavey was not afraid to invest 100's of thousands of dollars into tool and die making. """""" Now the rest of this story is that Peavey Electronics actually scooped EV in that Peavey brought a complete loudspeaker system with a CD horn to the market place, which was the very first SP-1 enclosure."""""" We were just down the hall from EV at the Waldorf Astoria at the AES convention ion NYC. EV was delivering an AES paper on the new CD Horn technology at that very convention, and just 2 doors down the Hall from their exhibit room, Peavey actually had a finished working model horn in a releasible product.

Note: the initial info in this story was told to me a few years later by John Gilliom's partner Paul Bolivar who also worked at EV at the time.

Since the mid 70's practically every manufacturer has their version of the CD horn. There is actually a relatively new horn technology called the Quadratic Throat Waveguide from Architectural Acoustics. Although Constant Directivity horns were a benchmark improvement over past devices, they still have their issues, when trying to create arrays to emulate a point source. They all have issues not widely discussed when it comes time to array them. There is a blurring of the produced wavefront that is analogous to astigmatism or a form of lens distortion. The Quadratic Throat Waveguide is another step forward in quality of reproduction. For more on this technology information please go to this URL, for a white Paper by John Murray: http://www.peavey.com/media/pdf/aa/qwp1.pdf

The above information is intended as historical information for those of us that appreciate the efforts of those who came before us.

marty

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