Building A New System Around Some SDA SRS2.3TL Speakers

indytriple

Hello all,

I recently picked up a set of SDA SRS2.3TL speakers from a local estate auction.

I'm going to build up a system around these speakers. I'm a record store owner and music nut, but I'm not what you'd call a traditional audiophile. I'm pretty unfamiliar with the equipment and the nomenclature that goes along with this type of advanced gear, but I'm willing to learn. I also have an amazing vintage audio servicer/reseller in town here that can really help me out with the other pieces of the system I will need (Getchell Amplifier).

The first thing I want to do before I spend any money on any other components or upgrades for the speakers is to test them. Currently, the only unit I have available to test them is aclean, well-working, late-70's Kenwood KR-4070 stereo receiver that has only 40WPC. I realize that this isn't a suitable unit to drive these speakers properly, but can I at least use it to safely test them to make sure that they work? I am also aware that these speakers require an amplifier with a common ground. Based on what I can find, it seems as if the Kenwood meets that requirement, but I'm not sure. Any advice on that topic?

The speakers did not come with an interconnect cable so I purchased a decent KabelDirekt RCA Hi-Fi, Double Shielded cable from Amazon, and modified it to remove the metal blades around the prong. It seems to fit perfectly in the pin portion of the pin/blade interface.

I'm looking forward to getting these tested so I can then begin to invest and build a proper system around them. I already have a wonderful listening space in a very large room where they can be placed and set up appropriately. Since I own a record store I already own most of the Polk recommended playlist for this speakers either on vinyl or CD. I can't wait to make my way through the list once everything is setup appropriately.

Thanks in advance to anyone on the message board that is able to help me along.

Cheers,
Jonathan

F1nut

Welcome to the rabbit hole.

The Kenwood is safe to use, but definitely not enough to do justice.

Emlyn

The receiver will be fine for testing at a low volume. A trick for listening to hear the tweeters working or not is to get the roll from a roll of paper towels and put that up to your ear over each tweeter. They won’t all sound exactly the same. With no music playing, you can gently push in on the midwoofers equally a few times with all fingers to hear if there are any scratching sounds indicating that the drivers are not moving freely. Take the passive radiators off and look inside the cabinet to see if there are loose wires hanging down or if the batting material has slipped down from the upper cabinet section from being moved around,

I would not use the receiver to listen to music for long, just enough to make sure all the drivers are working. Have fun!

audioluvr

Welcome. They have great potential but done right take a certain amount of determination. Where do you call home?

Tony M

Emlyn wrote: »

The receiver will be fine for testing at a low volume. A trick for listening to hear the tweeters working or not is to get the roll from a roll of paper towels and put that up to your ear over each tweeter. They won’t all sound exactly the same. With no music playing, you can gently push in on the midwoofers equally a few times with all fingers to hear if there are any scratching sounds indicating that the drivers are not moving freely. Take the passive radiators off and look inside the cabinet to see if there are loose wires hanging down or if the batting material has slipped down from the upper cabinet section from being moved around,

I would not use the receiver to listen to music for long, just enough to make sure all the drivers are working. Have fun!

I did just that with those new/used tweeters I bought off of eBay a week ago. I put the replacements in without testing them because they looked so darn new. I put some low volume to the repaired speakers and put my ears close to the speakers. I thought they weren't playing loud enough or not at all.

So I got the paper towel cardboard roll I have just for listing to specific drivers and sure enough, the tweeters were playing fine. I slowly kept turning up the volume and soon enough, the tweeters were heard plainly blended with the woofers.

I've also used "Christmas wrapping paper" cardboard tubes for years.

It's amazing how these tubes isolate soundwaves like they do.

Mike Reeter

Congrats to the O.P. on your new SDA's. The 2.3TL's don't demand a massive amount of Power, but do like a healthy dose of Current. A good used Parasound A21 Amplifier is a near perfect fit.

They are certainly worthy of building a good System around, as they will continue to respond to every upstream upgrade that you make along the way.

But, as you realize they won't be to their full potential until you perform the documented modifications and upgrades.

lightman1

Bobby G knows his stuff. I've been to his shop several times and bought a set of speakers from him. Rock on with more current!

indytriple

Y'all are a big help! Thanks for the quick replies. I really appreciate all of the help.

I'm in Brownsburg, Indiana for those of you that asked (NW-side of Indianapolis).

Here's an update:

Before hooking them up and testing them, I carefully moved each mid-range speaker in and out carefully with my fingers per Emlyn's tip. Each speaker moved very smoothly and quietly. Also, when I moved the passive radiator in and out gently with my fingers each mid-range speaker moved in and out along with it so the cabinets are sealed well.

I got the speakers hooked up with my diminutive Kenwood KR-4070. I can hear some slight distortion at very high volume levels, but I'm generally a low-to-medium volume listener. At those volumes everything sounds very crisp and clear. I'm sure it's nowhere near the potential of what the speakers can sound like, but at least I know that they work. I can now begin to enjoy them and restore them in earnest.

I still need to get inside them to have a look at the wiring/bracing/baffling.

I did remember that I own a commercial-series amplifier that I have used for the last 30 years as a casual side-gig DJ. It's a Peavey CS-400 from the mid-80's. Per the user manual it is rated and recommended for home Hi-Fi use as well as commercial use. I recently had it completely refurbished and restored by Kevin Silva at Uncle Albert's Amplifier repair here in Indianapolis (highly recommended) so it is in tip-top shape. Should I get that out of my DJ rack and give it a try? Is it common ground and safe to use? I realize that it won't have nearly the refinement of a good, high-end audiophile amplifier, but perhaps it will feed these speakers some of the power they need and take me one step further along in the meantime.

Here are the specs for the Peavey CS-400 from the manual:
Frequency Response:
+0, -1.0dB, 5Hz to 40KHz @ 1.0 watt, 4 ohms
Power @ Clipping:
Typically: (1.0% THD, 1.0KHz, 120 VAC line)
150 watts RMS into 8 ohms
260 watts RMS into 4 ohms
150 watts RMS into 2 ohms
Rated Power:
200 watts RMS into 4 ohms (Both Channels Driven)
400 watts RMS into 8 ohms (In Bridge Mode)
Intermodulation Distortion:
Less than 0.1% from 20mW to 200 watts RMS into 4 ohms, Typically below .05%
Total Harmonic Distortion:
Less than 0.1% from 20mW to 200 watts RMS, 20Hz to 20KHz into 4 ohms, Typically below .04%
Slew Rate:
20 V per micro second
Hum & Noise:
95dB below 200 watts RMS output (20Hz to 20KHz)
Load Impedence:
4 ohms or greater (stable in any load configuration)
Damping Factor:
Greater than 100 (1.0KHz, 4 ohms)
Input Sensitivity:
1.0 volts RMS for 200 watts, 4 ohms
Input Impedence:
50 K ohms (input overload protection)
Load Protection:
Short, mismatch, open circuit proof, voltage/current limiting instantaneous with no thumps or cutout
Speaker Protection:
Instantaneous crowbar circuit clamps the output upon advent of amplifier failure.
Power Consumption:
900 watts, 120 VAC, 50/60 Hz
Weight: 40-45 Pounds

Any and all thoughts and suggestions appreciated. I'm happy to stick with the Kenwood for the time-being if that seems like the best option.

BTW, I recommend listening to the Flim & The BB's album recommended on the Polk list. Great dynamics!

Cheers,
Jonathan

invalid

The kenwood is the better option until you can get a home audio amplifier. Pro amps have the power but don't sound very good, as they are made to play loud and not break.

Navy_Goat

Congratulations! For now, why not try both and see what sounds better?

gmcman

As far as pressing on the passive to observe the mids, you want to press the passive in gently and hold it, then observe how quick and/or how long it takes the mids to relax, should be about 3 sec.

I personally would look to other means of amplification than a pro-style amp. Those big SDA's will benefit from fresh components and good, clean, high-current power. Sure, they will work, but if you want to enjoy those speakers to their fullest, the cleaner the signal, the more of the SDA experience you will enjoy.

Here's a good analogy, take a flow of water that's running 5 gal/min. What does the water look like flowing from a hose with a nozzle compared to without the nozzle. Without the nozzle the water looks clear and with it has more of a transparent appearance. You want clean, high current power at low volume "settings" , not high volume "settings" . You should be able to drive the speakers at very loud levels while staying under about half of the volume setting. HTH.

pitdogg2

Many members live near you @indytriple
@Bigbang
@EndersShadow
@trav0810
@indyhawg
@Indyaudio2

Bigbang

We should have a mini polkfest.

Gardenstater

THD and IM both less than 0.1% ain't bad. How do you get power without current? I never understand that.

invalid

Gardenstater wrote: »

THD and IM both less than 0.1% ain't bad. How do you get power without current? I never understand that.

There is always some current, but some amps produce higher voltage and lower current to get watts, while others use higher current and lower voltage.

xschop

invalid wrote: »

Gardenstater wrote: »

THD and IM both less than 0.1% ain't bad. How do you get power without current? I never understand that.

There is always some current, but some amps produce higher voltage and lower current to get watts, while others use higher current and lower voltage.

At Club Polk, V=IR is a myth.

invalid

At Club Polk, V=IR is a myth.[/quote]

I did not know that, that's good sssstuuffff!

Schurkey

indytriple wrote: »

The speakers did not come with an interconnect cable so I purchased a decent KabelDirekt RCA Hi-Fi, Double Shielded cable from Amazon, and modified it to remove the metal blades around the prong. It seems to fit perfectly in the pin portion of the pin/blade interface.

The center pin may "fit", but that cable probably has a tiny conductor inside.

Contact the seller, see what they're using as the conductor. OEM was 16 or 18 gauge.

dpowell

Congrats on picking up some great speakers! Your journey down the rabbit hole has just begun. You will have to decide on priorities based on funding but I always recommend getting the crossovers upgraded first. Those old caps and resistors are way beyond their intended life and the speakers will never acheive their intended sound without new components. There are many threads on here to help you with that when you are ready. I went with sonicaps and mills resistors on my 2.3TLs. Bass came alive after that upgrade.

Also be on the lookout for a good preamp and amp. A standard receiver will make them work. Great pre and pro will make them sing.

verb

Awesome snag OP! And welcome to CP! Lot's of good advice here to help you on your journey!

indyhawg

Congrats on the speakers. I am about an hour from you, but we have a good group of folks here in Central Indiana who can help you. Feel free to reach out to any of those @pitdogg2 listed in his post for assistance.

ken brydson

verb wrote: »

Awesome snag OP! And welcome to CP! Lot's of good advice here to help you on you spend your money!

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