IPL Transmission Line Speaker Revelation

[Scroobius]

I have been reticent to post this without someone else whose ears I trust also listening for fear of questions regarding my sanity. Luckily Nick came by yesterday and he will post his thoughts separately. Really this post is about what properly designed, engineered and implemented transmission line speakers can do. However I just wonder if IPL are the only ones out there. I say that because I have heard highly regarded PMC Tx Lines and they were not in the same class.

There is no word other than "revelation" to describe my experiences with IPL speakers. I have now built three speakers in the range S2 (for my brother), S4 (for a friend as he was so impressed with the S2's) and finally for me the mighty S5's.

My comments on sound quality apply to all the above speakers as is seems the speakers are designed for different room sizes and it is not necessarily the case that "bigger is better". Choose your speaker with care!.

Over the years I have heard just about every type of speaker and I have never heard any speaker that produces proper bass. And it is not a question of how low they go it is more about its quality.  Maybe the biggest problem with box speakers is that rear going wave from the driver hitting the back of the box and bouncing back through the drive unit giving rise to colouration and time smearing. Yuk I really do not like that sound and it seems to be present in most speakers right from expensive to cheap. Other speakers have other problems open baffle and panel speakers could work in a big enough room but in the real world who has a big enough room?.

I cannot describe the character of the S5's (or S4/2's) as they do not have a character as such. Colouration is the lowest I have heard. From highs to lows the sounds are properly separated. Each subtle strand can be heard clearly. It is really hard to imagine that the sounds are actually coming from a box. S2,4 and 5 all produce the most natural rendition of human voice with very little boxy colouration. But then if there is some deep bass in the recording it is played clearly accurately without drama just naturally.

Yesterday Nick and I listened to a Grant Green track with some electronic organ. Overall the recording is light and airy with guitar drums and cymbals almost sounding electrostatic in nature. But there is some extraordinary low bass from the organ that I have never heard before that the S5's produces effortlessly - and it is a shock when you first hear it - you almost feel the bass and it just seems to be separate from the speaker. No other speaker that I have heard does this. Guitar and plucked strings just sound amazingly natural.

I have always been struck by how a real church organ sounds in a church. There is a lot of subtle detail, harmonics and little strands of sound. There is no wash of bass in the sound but you just hear little strands of deep bass occasionally and very clean. No speakers I ever heard get anywhere near reproducing church organ - until now. Church organ is stunningly natural via the S5's.

Ivan Lesley (he is IPL) gets big respect from me he has put years of engineering development and tweaking into his speaker range (and particularly crossovers) endlessly playing with crossovers and drivers to come up these transmission line speakers that I have to say I find astonishing. The key has to be removing/reducing that rear going wave problem. What other speakers do that without the real life open panel problems? I can only think of these IPL's and possibly Bert's Waves (but unfortunately I have never heard them). Of course there may be other speakers but they would be outside of my experience.

Just one last thing when any of these speakers play deep bass (and oh boy do they play deep bass) the drive units hardly move - also there is very little air coming out of the port at the bottom of the speaker - a very good sign!.

IPL has turned upside down many pre-conceptions I had about how to get great sound quality from a speaker.

These speakers are not expensive in materials but it could take around a week on and off to make a nice job of building them. But you will be rewarded with something very special.

By the way S5's are big much bigger than they look in the picture.

Paul

[SeVeReD]

Thank you for this post.  My huge speakers are long in the tooth (or is that me) and I'm beginning to think drivers are not matched anymore, along with some super tweeter concerns.  I like a good stereo image (along with all the more important stuff) and after reading I'm starting to think I'd like to build the S5s... but I go at these decisions very slowly now.

[Nick]

I'v been looking forwards to hearing IPLs for the first time. As Paul mentioned he's built 3 sets of different IPLs over the last few weeks and its been fascinating hearing about them from a distance as the results have unfolded.

Well this weekend I heard the TL4s that Paul built for a friend and Paul's own TL5s (in the picture above).

The TL4 delivered a very sweet top end, excellent stereo imaging and  low register resolution and extension that I have not come across before. Not a hint of boom, just real sound detached from the speakers. Paul's friend played an acoustic guitar track, the TL4s made it posible to sense the tension in strings and really hear the resonances of the boy of the instrument. Then there was Massive Attack......... :-)

Back at Paul's in his larger and very difficult shaped listening room the TL5 where really special, absolutely no problem driving the difficult space with a sense of ease. The first thing that strikes you is just how coherent they are, there is almost no sign at all that these are three way speakers. Then you try to analyse the sound only to find your attention slips time and again to just listening to the music. Humm, there is very little that you can latch onto to analyse the speakers are just making music and that's what you end up hearing not "attack" "decay", "highs" "transients" etc etc they do all this but quickly you realise they sound right and just listen.

Highlights are the very tuneful and realistic lows and a very transparent midrange. But they are extremely good top to bottom.

(The above comments on the TL5s are in the context of Paul's excelant PC, NOS1 DAC, and bi amped, bridged gainclones)

In the flesh they are certainly larger then they look in Paul's pictures. Overall very handsome, and a credit to Paul's craftsmanship and IPLs excelant engineering.

A very interesting and enjoyable visit, many thanks Paul.

Nick.

[listening]

Hi Paul,

the TM loudspeaker principle surely benefits from the xxhighend software. A lot of years ago I owned a pair of IMF TLS 50 and was very satisfied - until I moved to another location. I got a lot of resonances in the new room and sold the speakers. It would be interesting to hear them again 

Georg 

[Scroobius]

I forgot to mention that about 18 years ago I built a pair of Transmission Line speakers based on what was a very highly regarded design at the time. We were still in the same house then but the room was a different shape. My experiences with those TxL's was very different they just did not work well whatever I tried. I had had big hopes for transmission line speakers then and I was disappointed.

However back in those days I do not think there was a mathematical model for TxL's. There is now though and with much engineering and development (by someone who has passion and dedication) the results that I hear cannot be compared with that early effort.

Regards

Paul

[manisandher]

Hey Paul/Nick, thanks for sharing your thoughts.

I'm planning on taking a trip down to Paul's next week (exact day still TBD) as I'm really interested in hearing the IPLs for myself. I've visited Paul's place on a couple of occasions already, the last I suppose around a year or so ago, and have been massively impressed - totally different sounds on both occasions, but both absolutely listenable. So my expectations are nigh-on stratospheric this time. I'll share my impressions as honestly as I can once I've visited.

More next week...

Mani.

[Scroobius]

Oh Dear!!!! - Stratospheric expectations is a bad thing - they can only lead to disappointment.

I made the first of a couple of tweaks to the S5's today so that they work better in this room. The result is that with one quick tweak to internal damping (after a long chat with Ivan) I was able to achieve pretty much exactly what I aimed to. But of course extended listening is needed. There is another tweak on the way ..... watch this space!!! I shall be looking out for a little parcel in the post over the next couple of days.

So these speakers start off sounding really great but then in addition there is the freedom to modify them to match the listening environment. Manufacturers of speakers do not stand a chance!!

Paul

[Mamba315]

Any update on the S5's?  I am in need of some affordable speakers to tide me over while Peter and Bert finalize their design.  I was considering the waveguide S5's.  I have a friend with a wood shop too, but not sure if he would let me use it yet.  I think I would prefer wood cabinets over MDF though.

[PeterSt]

Haha, I don't want to interfere, but the design is ready by now. Playing here as I never heard anything before.

That's all !
Peeter


PS: Sorry, but I had to respond to that.

[Scroobius]

Hey Peter - The point is the performance versus COST these transmission lines are absolutely superb. Better than anything I have heard to date overall (REALLY). And they are silly silly cheap (but lots of hard work to build).

Apologies Mamba I do not know your name but you are very welcome to come along for a listen (and a coffee and a chat) and make up your own mind.

For anyone prepared to put in the work these are the bargain of the century. Really.

BUT BUT BUT you must make sure the speakers are the right size for the room. The S5's can put out a lot of bass energy the S4's are also superb and will sound better in a smaller room.

Peter - the Orelino's look fantastic and the design and engineering fantastic but for sure they are going to be VERY EXPENSIVE and not everyone has pockets that deep.

UNLESS that is you can say otherwise. I hope you (or Bert) can because you will have my order tomorrow (REALLY). But I know you cannot - 6 x 12" bass drivers just for starters mmmm then the horns the woodwork the in built electronics etc etc - please tell me I am wrong but that is serious dosh.

The IPL's are designed to be neutral and they are very revealing so you must make sure your front end is excellent.

How do they sound? - neutral & natural not dramatic in any way. They will just make what you were listening to before sound coloured (IMHO that is).

Cheers

Paul

[Scroobius]

Hey Mamba - I forgot to add that the waveguide S5's are what I originally looked at but after a chat with Ivan (the designer) he recommends the ribbon tweeter version for better sound quality. The waveguide version was made for very low power amps.

Also I did not properly read your post I missed that you are waiting for the Orelino's. That is great. For sure you cannot go wrong with the S5's whilst you are waiting.

If you are going to build them from wood maybe have a chat with Ivan first - he has taken great care in the design to get neutral sound and that may be affected with wood. I am sure he will have experience of that or someone who has built them will have.

Anyway hope all goes well if you do go for them.

Cheers

Paul

[Mamba315]

Peter,
  The Orelino's are ready perhaps, but the other?

Paul,
  Quite right about the massive cost difference between these IPL's and those Orelino's.  I think I need to save more money if I go Peter/Bert's method.  Just in case something unexpected were to happen.  In the meantime, I do need something better and these IPL's are under strong consideration.  I live in the States (California) so an audition may be somewhat difficult for the IPL's.

Am surprised to learn that the waveguide version is for lower powered amps.  Sensitivity is only 1db higher (92 vs 91) and power handling is actually much higher (500 watts vs 200 watts).  Did he really say the regular S5's sound better?

S5's could definitely do well for my present location.  How is the SQ as you walk around the room?  In practice, I'm rarely in the sweet spot.

[PeterSt]

Mamba,

The others are the same and two pairs are being build right now. But maybe this is too much secrecy and I better send you a mail.

Regards,
Peter

[Scroobius]

Hi - Yes I was surprised as sensitivity is so close to the ribbon version - but Ivan was clear that the ribbon version is best for SQ.

My S5's are 8' apart and I sit a non ideal (for imaging) 27' away from them so imaging is not a priority for me. There are four seats available around my seating position and the sound is fine in all those seats.

As you will see from the photo's the ribbon tweeter is at the bottom of the three drivers so the speakers need to be angled back.

What size room do you have? The S4's may be worth considering also they work in a wider range of room sizes.

Cheers

Paul

[PeterSt]

What size room do you have? The S4's may be worth considering also they work in a wider range of room sizes.

I really (really) don't want to interfere, but since Mamba's room is maybe the nicest I have ever seen, which right away makes it the strangest ...
... I will try to answer for fun. Ok, to help.

Now let me estimate ...
43'-46' from all sides to all sides. I am implying a circulair room here.
Height maybe 33'.

View from the room is outrageous. But that's something else.

Peter