A pair of SLAs... Perhaps..

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JensToft91
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A pair of SLAs... Perhaps..

#1 Post by JensToft91 »

Hi all.

I'm thinking about building some SLAs, that I really don't need. I'm just really curious about the concept of leaving the "expensive drivers and very precisely tuned filters" for high sensitivity and therefore low distortion, and then rely on EQ to take home the cake.

I have the classic 2.5 DIY kit from Paul Carmody, and I absolutely love everything about them.

I will maybe build these to see, if they can actually beat them - and if the hi-fi world is totally nonsense.

First: Driver selection. I want to go as cheap as possible.
GRS 4PF-8 for the woofers (a bit boomy, but EQ will take care of it, hopefully)

First question: is it possible to modify the crossover/wiring to use 4 ohm drivers? I'm thinking about these:
GRS 1TM-4 1" Mylar Replacement Tweeter 4 Ohm

The are dirt cheap, and seems perfect for the job - except for the impedance.

Thank you in advance for any replies and answers.

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AntonZ
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#2 Post by AntonZ »

JensToft91 wrote: Fri Jul 22, 2022 12:35 pmI will maybe build these to see, if they can actually beat them - and if the hi-fi world is totally nonsense.
Not entirely sure about that, but so far just about all my pair of Pro SLA's have done is provide me with music in my man cave aka home office when working from home. I have been working from home a lot over the last two years so they have seen a lot of use. Woofers are the standard Alpha-6. Tweeters are arrays of 6 pizzers, cut and glued. Music coming from my PC. Four-channel sound card, crossover and EQ are handled in the PC (Equalizer APO), a pair of decent home power amps, one is driving the SLA's, the other uses one channel to drive my AutoTuba, tucked away in a corner. It works totally fine for me. I do not long for anything more than this can give, other than perhaps dig out my T18. It should provide a tad more bass. While that would be satisfying, it might also make for too much of a distraction while working :lol:

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Bill Fitzmaurice
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Re: A pair of SLAs... Perhaps..

#3 Post by Bill Fitzmaurice »

With 4 ohm tweeters wire them as two banks of three in series, the two banks parallel.

JensToft91
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Re: A pair of SLAs... Perhaps..

#4 Post by JensToft91 »

If it's possible, the project is very likely to happen. 94 USD for all drivers. 8 woofers and 12 tweeters.

I read in another thread that stuffing the cabinet dense with isolation will help with the boominess. I'll probably do that.

I actually believe these will blend better with the sub than my current speakers are. My room is very lively at 30 Hz, which my other speakers will play. The crossover from the receiver is not steep enough to stop them from playing 30 Hz, and that interferes with the sub.

Then there's the 100-150 Hz dip from having the speakers away from the wall - that will go away from wall hanging these.

Before I know it, my beloved classic 2.5's is sitting in the garage. R.i.p

JensToft91
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Re: A pair of SLAs... Perhaps..

#5 Post by JensToft91 »

I'll also be using this thread to write down thoughts. I'll try to keep out unnecessary ones.

I'll probably pay a bit more to get the recommended woofer, as the sensitivity is 7 dB higher..

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Bill Fitzmaurice
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Re: A pair of SLAs... Perhaps..

#6 Post by Bill Fitzmaurice »

Don't stuff it until you're sure it needs it. Lightly fill it first.

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Tom Smit
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Re: A pair of SLAs... Perhaps..

#7 Post by Tom Smit »

JensToft91 wrote: Fri Jul 22, 2022 2:04 pm If it's possible, the project is very likely to happen. 94 USD for all drivers. 8 woofers and 12 tweeters.
Is that the quantity per cab?
TomS

JensToft91
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Re: A pair of SLAs... Perhaps..

#8 Post by JensToft91 »

Tom Smit wrote: Fri Jul 22, 2022 10:29 pm
JensToft91 wrote: Fri Jul 22, 2022 2:04 pm If it's possible, the project is very likely to happen. 94 USD for all drivers. 8 woofers and 12 tweeters.
Is that the quantity per cab?
Would be quite serious! But no. 4 woofers, 6 tweeters pr cap.

And thanks Bill

howiez
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Re: A pair of SLAs... Perhaps..

#9 Post by howiez »

I like budget builds, and I've thought about some SLA's for my HT. I'll be keeping tabs on this!

JensToft91
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Re: A pair of SLAs... Perhaps..

#10 Post by JensToft91 »

howiez wrote: Sat Jul 23, 2022 8:42 am I like budget builds, and I've thought about some SLA's for my HT. I'll be keeping tabs on this!
Thanks Howiez! I'd like to go for the cheaper woofers- but I'm too worried about the low sensitivity. 84 dB Vs 90-91. I think it will be overly bright / not efficient enough if I go for these.

So recommended woofers, and cheap tweeters.

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Bill Fitzmaurice
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Re: A pair of SLAs... Perhaps..

#11 Post by Bill Fitzmaurice »

Never trust SPL figures without running the numbers. The GRS is actually higher in sensitivity in the midbass, the same everywhere else. That's why it may be somewhat boomy. But the room influences that as well, hence my advise not to stuff and compress the cab until you're sure it needs it.

JensToft91
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Re: A pair of SLAs... Perhaps..

#12 Post by JensToft91 »

Bill Fitzmaurice wrote: Sat Jul 23, 2022 11:30 am Never trust SPL figures without running the numbers. The GRS is actually higher in sensitivity in the midbass, the same everywhere else. That's why it may be somewhat boomy. But the room influences that as well, hence my advise not to stuff and compress the cab until you're sure it needs it.
Wow, okay! I was comparing GRS to GRS, so i thought i was comparing Apples to Apples.

If you're not "scared away" from the cheaper woofers, i'll go for the full budget build.

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Bill Fitzmaurice
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Re: A pair of SLAs... Perhaps..

#13 Post by Bill Fitzmaurice »

I thought you meant the Goldwood GW-4028 and the GRS 4FR-8. The GRS4PF-8 is similar to the 4FR-8, I'd get whichever is less expensive.

JensToft91
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Re: A pair of SLAs... Perhaps..

#14 Post by JensToft91 »

Bill Fitzmaurice wrote: Sat Jul 23, 2022 2:02 pm I thought you meant the Goldwood GW-4028 and the GRS 4FR-8. The GRS4PF-8 is similar to the 4FR-8, I'd get whichever is less expensive.
I should probably be more specific, when I'm writing comparisons.

Thank you, Bill. Guess I'll take your word for it. Loudspeaker database seems to show quite the difference in sensitivity. I've attached screenshots of both.
I just don't want to save 20 euros to screw the build up.
But I won't screw it up, because you wouldn't be recommending it if it didn't work.

I'm going full budget
Attachments
Screenshot_20220723-212129_Chrome.jpg
Screenshot_20220723-212207_Chrome.jpg

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Bill Fitzmaurice
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Re: A pair of SLAs... Perhaps..

#15 Post by Bill Fitzmaurice »

Their data is flawed, because modeling programs are only accurate up to about 200Hz. They also show results if mounted in a wall baffle, not enclosures of equal size. Worse, they measure one at 2.83v, one at 4.0 v. I don't know what that's all about, but it accounts for a 3dB difference.

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