TLAH sound

For livingroom sound better than in a theatre.
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Line92
Posts: 48
Joined: Wed Apr 15, 2020 12:54 am
Location: Sweden

TLAH sound

#1 Post by Line92 »

Hello, i built myself a pair of TLAH and used GRS 4PF-8 and Goldwood GT-302/S from Soundimports.
I am really impressed with the sound but im not sure if i did something wrong, they really lack bass/low-mid.
I tested all the drivers individually and sorted out a couple of bad tweeters, luckily i purchased 6 extra tweeters.
Filters are as close as possible to the plans with good components. Tripple checked all connections and polarity of all the drivers. Tweeters give a total of 5.1 ohm. Woofers a total of 7.1 ohm.

I did not came across any problems during the building, i centered and glued the tweeters to the back of the baffle with a thick silicone-like black sealant, and used a thin layer on the midbass front gasket. Checked all the sealings separately with air and light, did not find any leaks then.

But when i now have followed the plans and tested polarity, damped them and then did some more frequency sweeps, i noticed very noisy air leaks through all tweeters when using a 50-120hz tone.
I checked all the tweeters again and did find out that the GT-302 has 2 small openings just under the connectors, so i sealed all those holes, tested the cabs and i still have some air leaks through them. And it is not coming from the tweeter-baffle seal.
Anyone else that had this "problem" with these tweeters?
I have not noticed the noise when playing music tho, maybe a bit with bass heavy music and loud levels.

But i feel like they lack some bass/low-mid, from 80-270hz they are pretty weak compared with the rest of the upper range 300hz and up. Tried to use a bit less damping and i think it helped maybe just a little bit, first time it was pretty heavily filled.

I would like to try to make them sound a bit more warm and smooth without eq and then by using maybe a 3dB series/paralell resistor (L-pad) to the tweeters after the filter. But that will not help with the weak bass range.

Any ideas? Thanks in advance.
//Linus from Sweden.
Attachments
20230110_145015.jpg
Screenshot_20230129_203306_Gallery.jpg
SLA PRO 4X6
T60 2x20"
Labgruppen fP6400. fP2400Q. DBX Driverack PA2
TLAH
AT 20"
TRT

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Bill Fitzmaurice
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Re: TLAH sound

#2 Post by Bill Fitzmaurice »

Without seeing an SPL chart I can't venture an opinion.

Grant Bunter
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Location: Ilfracombe Queensland Australia
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Re: TLAH sound

#3 Post by Grant Bunter »

Hello, nice build!

I don't understand transmission line array theory well enough, so hopefully Bill will chime in soon.

I do notice though, that the specs of the GRS mid drivers quote useable response from 100Hz and up (to 10K), and unless the transmission line does magic, that might help explain a deficit below 100Hz.

One thing I know for sure, our ears deceive us, so, I'll ask the question; Did you measure response when you said "lacking from 80Hz -270Hz", or is that perceived?
Built:
DR 250: x 2 melded array, 2x CD horn, March 2012 plans.
T39's: 4 x 20" KL3010LF , 2 x 28" 3012LF.
WH8: x 6 with melded array wired series/parallel.
Bunter's Audio and Lighting "like"s would be most appreciated...

Line92
Posts: 48
Joined: Wed Apr 15, 2020 12:54 am
Location: Sweden

Re: TLAH sound

#4 Post by Line92 »

Bill Fitzmaurice wrote: Sun Jan 29, 2023 4:42 pm Without seeing an SPL chart I can't venture an opinion.
Okay, then next obvious question is, how do i do to get a SPL chart? :D
I have a DBX RTA mic, and a computer, thats it. What more hardware/software do i need to get to measure the speakers and get out a SPL chart? The least pricy alternative wins :lol:

Right of, do you think very small air leaks from the tweeters could be the source of my problem?
I would guess we are talking of atleast 8-10dB lower response below ~250hz.
Tried 2 different rooms, 3 different placings, not a huge difference in sound.
SLA PRO 4X6
T60 2x20"
Labgruppen fP6400. fP2400Q. DBX Driverack PA2
TLAH
AT 20"
TRT

Line92
Posts: 48
Joined: Wed Apr 15, 2020 12:54 am
Location: Sweden

Re: TLAH sound

#5 Post by Line92 »

Grant Bunter wrote: Sun Jan 29, 2023 4:52 pm Did you measure response when you said "lacking from 80Hz -270Hz", or is that perceived?
Hi and thank you!
No, perceived. But according to my ears they do really really slope down below 270hz. But i guess a measurement would be of great use here. I could maybe use my hand hold spl meter and take 10-20hz steps from 80hz-300hz and draw a curve manually from that?
But, i would like a good measured curve. Any input of what i need in hardware/software?
SLA PRO 4X6
T60 2x20"
Labgruppen fP6400. fP2400Q. DBX Driverack PA2
TLAH
AT 20"
TRT

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Bill Fitzmaurice
Site Admin
Posts: 28619
Joined: Tue May 02, 2006 5:59 pm

Re: TLAH sound

#6 Post by Bill Fitzmaurice »

I use HolmImpulse. There are a number of RTA programs available. REW is another.

Grant Bunter
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Joined: Mon Nov 28, 2011 11:12 am
Location: Ilfracombe Queensland Australia
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Re: TLAH sound

#7 Post by Grant Bunter »

Line92 wrote: Sun Jan 29, 2023 5:11 pm But i guess a measurement would be of great use here. I could maybe use my hand hold spl meter and take 10-20hz steps from 80hz-300hz and draw a curve manually from that?
If nothing else, your suggestion above may confirm there is an issue, while you search for a suitable programme...
Built:
DR 250: x 2 melded array, 2x CD horn, March 2012 plans.
T39's: 4 x 20" KL3010LF , 2 x 28" 3012LF.
WH8: x 6 with melded array wired series/parallel.
Bunter's Audio and Lighting "like"s would be most appreciated...

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Bill Fitzmaurice
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Posts: 28619
Joined: Tue May 02, 2006 5:59 pm

Re: TLAH sound

#8 Post by Bill Fitzmaurice »

I don't see mention of your subs.

Line92
Posts: 48
Joined: Wed Apr 15, 2020 12:54 am
Location: Sweden

Re: TLAH sound

#9 Post by Line92 »

Bill Fitzmaurice wrote: Sun Jan 29, 2023 10:09 pm I don't see mention of your subs.
I will try to make a manual C-weighted curve tonight or tomorrow from 70hz up, measured at 2 or 3 different locations in the room. It will be far from perfect but maybe it will be enough to see if there actually is a real problem or not from my building.
It could be my ears that are doing tricks.

Correct, i do understand that i need sub(s) to go lower than 100hz with enough spl to match the TLAHs response. I was thinking of maybe one or two 24" THTLP in the future.
But for now i would like to get them a litte warmer sounding alone. Now they are extremely sterile and cold, super crisp and clean, good stereo image and there is bass, but barely noticable when playing music. Im not trying to make these go lower than what is possible, just some more 80-250hz.

Do you think a baffle step correction circuit would be of use here?
SLA PRO 4X6
T60 2x20"
Labgruppen fP6400. fP2400Q. DBX Driverack PA2
TLAH
AT 20"
TRT

User avatar
Bill Fitzmaurice
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Posts: 28619
Joined: Tue May 02, 2006 5:59 pm

Re: TLAH sound

#10 Post by Bill Fitzmaurice »

No, because baffle step is a red herring. It reduces sensitivity by 6dB above where the baffle is 1 wavelength in dimension. That's all well and good if the speaker is used outdoors away from buildings, but it ignores what happens when the speaker is in a room. EQ is what you use, as it takes the room into consideration. TLAH will take quite a bit of EQ, since the total displacement of nine drivers is considerable.

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Seth
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Re: TLAH sound

#11 Post by Seth »

For contextual reference, presumably built and measured by Bill...


80Hz is 10ish dB down from mean sensitivity.
Build in process - 2 WH6, one Alpha 6a loaded, one PRV Audio 6MB250-NDY loaded

Two 2x6 shorty SLA Pro's
One T39, 16", 3012LF loaded
Tall AutoTuba, 20" wide, 2x 8" MCM 55-2421
TruckTuba, 8½" wide, 2x 8" MCM 55-2421

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Bill Fitzmaurice
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Re: TLAH sound

#12 Post by Bill Fitzmaurice »

That's mine.

Line92
Posts: 48
Joined: Wed Apr 15, 2020 12:54 am
Location: Sweden

Re: TLAH sound

#13 Post by Line92 »

I placed the speakers in my small livingroom thats 20m², far from optimal placement, but thought okay, lets give it a try.
Using SMSL DO200 DAC to a Yamaha P2500S spare poweramp. (YS Processing was off when i did the measurements) no eq or anything, same voltage level in all the frequencies.

So i started playing sine waves at 1.5v (my ears did not like any stronger) and sitting at the same place, around 4m away from the speakers, used my hand hold spl meter, not a correct way but its something atleast.

I noticed that the peaks and valleys where about the same amplitude but just moved slightly in the SPL range when i moved position. So i did only one positioning.

My hand written chart shows deep (15dB) valleys and peaks, thats from the room, nothing strange. The peaks and valleys change place and spl as i move the meter, pretty obvious.
I took 10hz steps from 60-400hz where i thought the problem was, then 50hz steps to 1k and then 1k steps and so on..

Wherever i listened the 300hz range was way more sensitive, the rest of the "measured" peaks/valleys was not as noticable as the 270hz valley and the 300hz peak. Pretty much the only spot i would like to change, and thats easy with an eq, but not sure if i could do something to it with the filters?
Nothing will be done yet before i could do a real measurement in a correct way.

However, when i was finished with the sine waves and i played music and started to write down the chart. I had a hard time writing because i was amazed how good the speakers sounded. ALOT warmer and better sounding with even more bass.
Did i judge it way to soon before drivers even got the first hour brake in? Did something else change, or it it only my ears that tricked me? I dont know but with just a little bit of eq i could solve this.
Well here is the result :lol:

The 3k peak should be at 94dB not 97... sorry
Attachments
20230130_180418.jpg
20230130_211455.jpg
SLA PRO 4X6
T60 2x20"
Labgruppen fP6400. fP2400Q. DBX Driverack PA2
TLAH
AT 20"
TRT

User avatar
Bill Fitzmaurice
Site Admin
Posts: 28619
Joined: Tue May 02, 2006 5:59 pm

Re: TLAH sound

#14 Post by Bill Fitzmaurice »

Before break in the suspension and spider are stiff, so Fs is higher than after they break in. The peaks and valleys are room sourced. My chart doesn't have them because I measured mine outdoors. Mic/listening position makes a world of difference as well: http://ethanwiner.com/believe.html

Keryn O'Shea
Posts: 444
Joined: Sat Jan 26, 2013 5:50 pm
Location: Brisbane, Australia

Re: TLAH sound

#15 Post by Keryn O'Shea »

Which species of timber is that Linus, and is it a stained finish? The colour is so nice.. also backmounting drivers to me looks much cleaner, more work but worth it.
Imagine how amazing the sound is going to be with a proper bottom end... you could drag in one of your T60s
AT8 14", AT10 19", T30 28" LAB12, T48 36" 3015LF, THT 20" LAB15, SLA 4x3"/4x4", CArray 6x4", TLAH, TLAP, J10 FLat, J12 Flat, OT12 Flat, OT15 CD, SLAP 2x6"/4x6", WH8, DR280 Mld'd, XF210. Next J10L

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