TG "The Loudspeaker" Build (Sort of)

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MistyBlue
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#1 TG "The Loudspeaker" Build (Sort of)

Post by MistyBlue »

Apologies for the long intro, but thought it would be relevant.

OK, so here goes……

I have been planning something like this ever since Troels published this design. I knew that it would be quite an effort to better what I built last time and cost considerably more, but I just couldn’t resist the size of those bass drivers!

I posted some of the following on DIYaudio as a homage to Lynn Olson’s “Beyond the Ariel” thread for the inspiration that it gave me, and I’ll repeat some of it here so you get the picture and where I’m coming from.

My current speakers were built in 2018 (30mm B/BB birch ply heavily braced and damped 230 litre cabs with Faital 15PR400 and HF146 HF drivers, crossover 3rd Order electrical at ~800Hz) which originally had JMLC425 horns. They are similar to the design that was discussed on that thread some time ago (15” Bass/Mid PA driver and 1.4” exit CD) with the GPA/Altec and Radian drivers, but with European drivers that are more easily obtainable in the UK and not to mention considerably cheaper. I played it safe with the choice of drivers, took some tips from others by trawling the various forums, got traces of measurements from multiple sources and simulated extensively before I took the plunge. When the cabinets were built, I took my own acoustic measurements and used VituixCAD to model the crossover. All the usual stuff.

They were a revelation to my ears, and I found them preferable to the Tannoy Windsors they replaced which sounded too overly refined and polite (being polite here - that old Linn advert comes to mind LOL). Both of us also prefer them to my previous Lowther based speakers and conventional cone/fabric dome hi-fi floorstanders.
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In 2021 I changed the original JMLC fibreglass horns because they were just too forward for extended listening sessions and 3D printed some freestanding OSSE waveguides with the rounded edges to reduce diffraction. This improved things greatly with the HF, reducing colouration and they became much less forward in presentation and simplified the crossover. Much better.

However, since then both of us in the household have found that we still get listening fatigue, and whilst the sound is brilliant, it is just a bit too much excitement. They do all of the music we like excellently (Mark Knopfler, Norah Jones, Tracy Chapman, Pentangle, Roger Waters, First Aid Kit, Carcass (!) etc, they are detailed, they have that big sound that we like, they work well with films/games/DAW/TV etc as well as music, and they are absolutely mesmerising with Nightwish (Floor Jansen is a Goddess!). So there is much that is good about them, and we will never go back to the conventional HiFi stuff. But it’s just this one main issue.

I’ve experimented with equalisation with the convolution filter in HQ Player etc, messing with the crossover and remeasuring (I have measuring microphones, ARTA, REW, even a specially made measuring trolley with a boom arm jig that I machined that can do angles (polars), that I can put the speakers on to take them outside and measure if needed) to get a fix on what’s going on, but whatever I try, I can’t seem to shake it. I point the finger squarely at the CD (the Faital HF146). I could change it, but I feel as though the compression driver is crossing too low. Not that it can’t technically do it, or I’m pushing the envelope. Using this sort of CD (1.4” exit) down to 800Hz at domestic listening levels (especially a UK living room) is not exactly pushing it. It might be fashionable (in some circles) to go as low as you can in these setups, but I have concluded I just don’t like it. Having experimented with other CDs, I’ve heard the same thing when going low (below 1.5kHz). Joseph Crowe does an excellent video on YouTube, demonstrating this with one of his projects and I can hear exactly the same thing there. On the forums, there are quite a few people who say the same thing about similar designs with compression drivers in general. I suppose it comes down to personal taste in the end.

I pretty much know we are on the right track with the PA drivers for HiFi type thing, mostly direct radiator (we don’t have space for big front loaded horns and they are just too ugly and imposing – we do have some limits), but I suppose we need that extra refinement. I did design the current speakers with an option in mind for putting an 8” midrange driver like a BC 8PE21 or something similar (TG has one with the 18 Sound 8NMB420). But when I tried to simulate in VituixCAD, it just didn’t seem to gel and get a suitable enough result (impedance, sensitivity) to go with the 2A3SE which we both adore.

Plus, I like those huge 18” bass drivers!

So here’s my plan. TG’s “The Loudspeaker”. Are they too big for the room? Maybe……. :) That’s part of the fun!

I admire Troels and I greatly respect his designs. Whilst his designs are a package, like IPL Acoustics used to do, there are couple of things that I have to do differently for practical and financial reasons. Taking one of his designs and modifying it is a lot safer than having to buy a load of drive units for a 4 way project, building test boxes, voice everything into something coherent by mix and match and still run the risk of getting into an almighty pickle. That sort of activity is way beyond my means at the moment, and frankly, I’d rather not get that involved at this time either. If it’s good enough for him to have built a second pair of them for use as his reference speakers with his experience, that says enough for me.

TBC
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#2 Re: TG "The Loudspeaker" Build (Sort of)

Post by Toppsy »

Hi,
I do like some of the TG speaker designs but do wonder if they perform as good as with a (how shall I put this?), a cheaper version of his chosen drivers (that always seem to be top-of-the-range from his sponsored driver catalogue), and not using the most expensive crossover components from the likes of Jansen who sponsor a lot of his designs. Still 'The Loudspeaker' is an interesting design and I wish you good fortune in the build.

Which of 'The Loudspeaker' versions are you intending to build? The original 'The Loudspeaker LT-1', 'The Loudspeaker-2' or the scaled down latest version 'The Loudspeaker-III'?

Though you make mention you believe the issue you have with your current speakers of fatigue over extended listening periods is perhaps down to the CD I do note that all three versions of 'The Loudspeaker' have CD drivers. I too have come to the same conclusion and find that every speaker I have listened to that has a CD I experience the same fatigues in the HF. To my ears I find the SB Acoustics Beryllium dome tweeters (Model TW29BN-B) overcome this issue and I believe to be one of the best HF drivers available today. These can be safely used down to 1KHz. However the one design feature I really do like and approve, is the use a Hypex amp to drive and tailor the bass to ones room. I fully endorse this method and use it in my own design Swansong speakers.

Do keep us updated of build progress as I will follow your project with great interest.
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#3 Re: TG "The Loudspeaker" Build (Sort of)

Post by rowuk »

I also use the HF146 that worked fine at 300 Hz with a 66cmTractrix horn. In the mean time I replaced the "large" roundover with a wooden ring (horn now 55cm) and now cross over at 450 Hz with phenomenal results. This driver is a keeper and 300 Hz was no problem - even with the distortion curves. A shallower horn will provide different loading and horns get honky if driven too low. Have comfort that it is NOT the drivers fault.
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The Karlson Coupler tweeter is being driven by a Beyma 1" compression driver.
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#4 Re: TG "The Loudspeaker" Build (Sort of)

Post by MistyBlue »

Hi guys, thanks for sharing your experience with me. I'll try and answer each of your points.

Toppsy - I know exactly what you mean about the cheaper drivers and crossover components thing. I have felt that the sponsorship issue has definitely influenced things with his designs - especially given that some of the simulations I have ran have suggested that more cost effective solutions re crossover and drivers (especially the bass driver) can be realised. The expensive caps is a dead giveaway for that one. I don't subscribe much to that sort of thing anymore after my own experiences with a few amp rebuilds using expensive components (including my current one). There is just not enough of an improvement for the cost. One builder did substitute the expensive BMS driver for a much cheaper Faital unit - and that is something I have done (I've already got the drivers). TG states on his site that a lot of his stuff wouldn't be possible if it wasn't for that sponsorship, so I am not going into this completely blind.

The closest version to what I am building would be the TL1 with some of the mods of TL2. However, this is a rather loose description - I am not using the same waveguide, as I am not convinced that the XT1086 would be best for us with the previous experience that we had with the JMLC (depth of horn). I also have a practical issue with the height of the complete cabinet of the design, so a freestanding WG will be used. Basically, I have kept in mind the issue TG mentions about the baffle width re the mid driver, kept the width the same, checked with baffle diffraction simulations, and I have designed a new cabinet accordingly.

So I suppose a more correct description of this thread maybe something like - I saw this, and fair enough, but I'm going to go my own way. Whilst I did mention about not getting that involved, I'm under no illusions of the risk with this approach and am fully prepared to go it alone with the HF section to get what we are after.

It's good to hear your comments about CDs re fatigue and have a number of contingencies should this occur, in that the freestanding WG can be replaced with an upper mid driver, or indeed something like the SB Acoustics Be dome as you describe. This was part of the initial evaluation before committing to the project. I have programmed in some wriggle room to make sure that I get this right with the choice of HF. I did have a look at your "Swansong" speaker build with the mid array - that's an amazing build and a fantastic design!

I am open to the idea of the the Hypex with the DSP, but one thing that doesn't make sense to me is taking the main amplifier output (in my case the 2A3) and then taking a tap off of it, making it line level, and passing it through an ADC to DSP and back to analogue. I suppose I could just take a line level signal split from the source and run it through a Hypex or similar. I have heard more than one person who has gone with the former approach mention that it just didn't sound right to them and reverted back to either passive or an active solution. But I certainly do agree with your point about using DSP to tailor the bass response to the room. My sources are digital only, so I have no problem with that.

Rowuk - It's good to hear that you had such success with the Faital HF146. Especially with such a low xover point. The OSSE WGs that I swapped out on my build certainly got rid a lot of the colouration we experienced with the JMLCs. I sold the JMLCs to a horn fanatic who was building a major project along the lines of a 5 way like Romy. I used to think (a long time ago) that that was the way to go, but I soon dumped that idea when I realised how much I dislike that sort of colouration. I could have put up with some of the cosmetics if the performance was as good as proponents claim. Thank you for sharing your experiences with this driver - It certain confirms what I suspected about personal preference. Love what you have done with the Karlsons, reminds me of some of the approaches with the MEHs. Measurements that I did on the HF146s did show that they break up and fall off around 14-15kHz. I ignored it, on the basis that my hearing drops off at 14kHz, but I'm sure I'm missing some sparkle.

The plan is that I will use the NSD1095N on an OSSE WG as before only smaller, with the xover at 1.3kHz as Troels designed it (changing the xover point would lead to other problems), and if we still decide that we don't like it we will look at the other options. I have done some simple listening of this driver with the prototype OSSE WG, and heard much less of the annoying (to our ears) forward presentation in the area around 1kHz. Maybe it's just I don't like the sound of a CD in this range - the rest of the HF sounded good. This point is what drove me to look at a dedicated cone mid. One alternative to the CD I have in mind is a wideband mid as Toppsy mentioned, or a single high mid driver such as the BC 5NSM38. I did even consider multiple high mid drivers funnily enough, including using dome mids - but I don't won’t to pre-emptively decide on that before we have lived with the current plan for a while.

I suppose the main thing is that we are leaning towards a dedicated, high quality mid driver and dedicated bass rather than trying to "stretch" bandwidths in a 2 way.

Of course, if I’m wrong and it doesn’t work out, I still have my current speakers. :wink:
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#5 Re: TG "The Loudspeaker" Build (Sort of)

Post by simon »

MistyBlue wrote: Wed Feb 21, 2024 8:49 pm One builder did substitute the expensive BMS driver for a much cheaper Faital unit - and that is something I have done (I've already got the drivers).
Which Faital drivers out of interest? Those BMS look impressive with a reckoned 28.5Hz from a vented 153L cab. That doesn't say how they would sound of course. Do the Faitals get close to the extension for the volume?
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#6 Re: TG "The Loudspeaker" Build (Sort of)

Post by vinylnvalves »

Having been involved with a pair of Troels DQWT in the past, I wasn’t impressed by that design.

On the topic of small horns, I am currently doing some horns for a 1.4” driver for an open baffle design, similar to the Perry Marshall OB speakers, but looking at using a newer horn design that has a weird throat -
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. Once the prototype has been measured and assessed, I will share more.

You may find this useful too.
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After a decade of using a midrange horn, I am using a 12” driver in my latest creation, that I brought to Owston last year, yes it beams a bit, but in a typical uk room that’s not an issue.
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#7 Re: TG "The Loudspeaker" Build (Sort of)

Post by MistyBlue »

Hi Simon,

Bass driver is Faital 18FH500. -3dB point is about 31Hz according to Vituix. WinISD (sanity check) came up with 32Hz. See simulation below. I did say I like big speakers! This is really the limit for us though!

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Group delay is slightly worse than the BMS. On the previous build, I went to the trouble of reserving the option of sealing the enclosure using an interchangeable ring or plug and doing a linkwitz transform. Seemed like a good idea.

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I had a silly idea that I probably picked up years ago from somewhere that you can always reduce volume of a cab if you really need to by filling it or baffling it off, but you can’t so easily increase it.

Hi vinylnvalves,
I have followed some of your work with your cnc router and various horns – awesome stuff! I’ve always been curious about the Beyma TPLs but never heard them. They are pretty expensive - so I would be nervous about going in blind. A lot of people have lots of good things to say about them.
Thanks for reminding me about the room/WG coverage size diagram – I saw it a while back on DIYaudio I think. Our ears on the sofa are about 3.5 metres away from the source.
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#8 Re: TG "The Loudspeaker" Build (Sort of)

Post by MistyBlue »

As mentioned, I got the drivers last month and have been breaking them in and doing preliminary measurements (impedance curves of the bass and mid drivers).In the sims,the bass driver’s sensitivity keeps up with the midrange driver and has good bass extension, so the option of a fully passive crossover is available if I choose to go that route. I have also designed a ROSSE waveguide using ATH4, 3D printed a prototype and done some acoustic measurements of them on the NSD1095N and plugged them into VituixCAD for crossover sim. So far, it’s stacking up well.

NSD1095NOSSE307Dsml.jpg
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I have also bought some Fountek Neo CD3.5H ribbons for supertweeter duty, as they did rather well in sims, and I liked the sound of them when I tried them a couple of years ago. I also designed a new WG based on an OSSE profile. I cut away the protection grill to measure the exit angle of the metal parts, with the intention of getting a seamless transition into the throat of the WG, and like a dumbass concentrating so hard on the job in hand, used metal calipers. :shock: Following the inevitable fallout, I ordered some plastic calipers. Sensing an opportunity out of this catastrophe, I ordered some 10.5um domestic aluminium baking foil on Ebay and subsequently changed the diaphragm (the standard is a 15um composite which looks like aluminium/kapton film which I weighed on an analytical balance at 0.0235g - the new 10.5um one is 0.0210g). This gave it a bit of a lift in sensitivity above 9kHz when measured but exacerbated the variations in response lower down. They will be crossed over at about 8.5 – 9kHz, 3rd order electrical, so that doesn’t really matter. The CSD waterfall plot also checked out ok. I tested the other ribbon, which was still in it’s box untouched, and discovered it had no output, so I returned that one to Caroline at Willy’s HiFi to be replaced, which they did promptly.

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#9 Re: TG "The Loudspeaker" Build (Sort of)

Post by MistyBlue »

It’s been a big day today, we both drove up to Keynsham (mind the step LOL) to pick up some birch ply from Sydenhams (formerly Avon Plywood). Used them last time, but prices have skyrocketed in recent years. I hope I don’t need to do this again, although I think I said that last time!

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I think I need to lie down now. :blackeye:
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#10 Re: TG "The Loudspeaker" Build (Sort of)

Post by simon »

Is that really a 300L cab? :-D Impressively big. And that must be a small fortune of birch ply.
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#11 Re: TG "The Loudspeaker" Build (Sort of)

Post by MistyBlue »

simon wrote: Thu Feb 22, 2024 9:07 pm Is that really a 300L cab? :-D Impressively big. And that must be a small fortune of birch ply.

Oh yes indeed :) , it really is the limit for us - I'm not joking! And yes it did cost a small fortune.

Fortunately, the guys at Sydenhams gave us a really good deal and used my cutlist optimiser layout to get the grain in the right direction on the important panels. The panels are 30mm thick.

We are going to have to play tetris to get these built, but the panels will need processing ie routing out etc if it ever stops raining of course!

I may be busy for a while!
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#12 Re: TG "The Loudspeaker" Build (Sort of)

Post by andrew Ivimey »

Wow! all the best for that then. Onwards!
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#13 Re: TG "The Loudspeaker" Build (Sort of)

Post by Dave the bass »

Watching this thread, its been a long time since a big speaker build.

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#14 Re: TG "The Loudspeaker" Build (Sort of)

Post by Tony Moore »

Me too! Can't wait to see the progress. 8)
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#15 Re: TG "The Loudspeaker" Build (Sort of)

Post by Cressy Snr »

Me three :)
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