Jenzen Illuminator, built by Steven
Copyright 2019 © Troels Gravesen

Hi Troels,
I have just set up the speakers for a test, all I can say is the the sound is truly remarkable and i am stunned at their performance. I have a whole new perspective on what recorded music can deliver! The test extended well into the night and my wife was also completely taken by what she could hear.
I still have to complete them as the cabinets have to be veneered to match the existing furniture, as soon as I have done that I will send some pictures across.
In the meantime I want to express my deep gratitude to you for making your knowledge and designs freely available, without it I couldn’t have got to the result I have.
Cheers and thanks again
Steven

Hello Troels,
 
Apologies for the delay in responding as I have been on a quest for improved sound and have completely rebuilt my HiFi system, largely inspired by yourself, so before I start, a very big thank you for all you have shown on your website. I don’t know whether you want to use all of this mail as it will be quite lengthy; it will cover many aspects of my HiFi system and not just the speakers.
 
Speakers
 
The beginning was around 2 years ago after Christmas when I was sitting down with my wife and we were discussing what to do and the question was raised as to why we didn’t listen to more music, looking at the existing system the answer appeared immediately, it was very old and was tiring to listen to, the question was what to do about it? The internet is a wonderful thing and very quickly speakers were seen as the first improvement opportunity, as someone who likes making things DIY came up and very quickly i had found your website. The first question was what size and type of speaker to build? As you say size matters, equally important is the WAF for final approval. I was looking for the best possible sound with the ability to play at a relatively low level, hence Transmission Line, the other factor was that I worked for Vestas at the time, had been to Videbaek many times and was surprised that at the back of the office there was the Scanspeak factory, consequently the decision was the Jenzen Illuminator. For final WAF approval they had to match the existing furniture, so were to be veneered in yew.
 
They were largely based on your design, except they were to be of a single cabinet construction, modular, allowing access all the internals when built. Following a quick exchange of emails with yourself there was to be a 2mm gap between the top of the bass and the M/T cabinet. For modularity the three major parts for each cabinet were to be the box, the baffle including the drive units and the crossover board including the base plinth. Pan headed screws were used to connect them together, this also allows for easier movement as once the speakers are assembled they would be too heavy to move by a single person. To maintain edge stiffness in the base section, as the baffle was not to be glued in place, additional pieces were added along the edge of the bass cabinet, whether this has any measureable affect is open to question but was easily done, the other thing noticed is that by making a single box the top of the base section is stiffer. The baffle itself was made of plywood, this is significantly stiffer than MDF, again whether this has an effect I do not know, however, as you say on your website plywood baffles are not so easy to work with, I ended up by using a round bevel finish for all the sharp edges. I tried to paint them myself, unsuccessfully, so I asked a local painter to cover them with a two pack epoxy paint, the results exceeded my expectations and gave the baffles a very professional finish,
 
Building was at the limits of the available space and tools, the sections of plywood for the speakers were cut by the local wood supplier on a professional table saw, in total this requires two sheets (2440 x 1220) of 24mm plywood for the cabinets and the two baffles come out of a single sheet of 15mm plywood with extremely low levels of waste. The only cutting I did was for the internal sections and the bases. The cabinets were glued together using biscuits with butt joints, this allowed good alignment to be made between the sections before gluing commenced, once in the gluing phase alignment could not be easily changed as the box assembly was both large and heavy requiring extensive clamping. The mid and tweeter box was built first with the bass being added as the second stage. A point to note is that you have to be comfortable working to tolerances of better than 0.5mm to achieve a rectangular box with good joints when using this approach, later adjustments are not really possible. The baffle was made by gluing together sheets of 15mm ply to get the 30 and 60mm thicknesses, the first stage was to glue the two larger sections to get to 30mm then rout the bass and treble driver holes then glue the smaller sections on to rout out the mid driver hole. The 29mm between the mid and tweeter was achieved by routing out the mid to a 1mm greater depth.
 
The components arrived from Jantzen audio, an excellent service, with final build and assembly then taking place. As you can access all the compartments it was relatively easy to fit all the internal damping after the main cabinets had been built. The modules are held together by hex drive flathead screws with countersunk hex screws used for the drive units, these are both screwed into inserts permanently fixed in the cabinet. Crimp connections are used fo connect the drive units to the wires and to allow the crossover board to be removed. Whether this affects the sound is a question that will be asked, my view is that there are bigger things to worry about. This modularity was tested later when the bases were removed to convert the speakers to Bi-Amping and later complete disassembly took place to add the veneer, in both instances this was straightforward.
 
Now we come to the testing, I set up the new speakers next to the old ones with the idea to compare, suffice it to say there was no comparison and the old ones went straight to the loft. The range, transparency and detail was stunningly different with whole new levels of sound appearing even when played through the old system. The other outcome was that the speakers very quickly highlighted the deficiencies in the rest of the equipment.
 
The total build cost was around £4000/€5000, the question is what would they cost commercially? I happened to come across the Vapor Audio site, if you look at the Joule Black or White you will see largely the same set up and drive units, admittedly on a very well finished cabinet, but I suspect with a very similar sound capability. The price on the website shows what the commercial value of the Jenzen speakers probably are as you will also have to include shipping, duties and local sales tax to the price.
 
Turntable
 
As I was building the speakers I was very impressed by your modification of the Lenco 75 with a new plinth; based on that I set about obtaining an old unit, this was probably the most difficult part as they are increasingly rare. An old Dynatron music centre was the donor, creating the plinth itself was reasonably straightforward after experience gained by building the speakers. The painting was done by the same painter who did the baffles, again a stunning outcome. The arm used was off the original deck I had, a Mission 774LC - a rebadged Jelco. With the original MM cartridge the performance was stunningly better, both the top end and bottom appeared as if by magic. A Denon MC cartridge was then used which took it a step further, once I had built a suitable phono amplifier, yet another story.
 
PreAmp
 
I was impressed by your TRAM with output transformers, I had already identified that I was looking to BiAmp the speakers so I looked into how to make it. The final outcome was to put it in a professionally made box (Modushop by Hi-Fi 2000), the power supply was to be the PS1 from the TubeCAD website with the output transformers from Sowter. The remaining components came from HiFi Collective. I roughed out the layout to ensure that everything would fit, it was going to be tight, using 6N6P valves using a 2U height box meant that there would be only 1-2mm clearance both top and bottom. The only real change I made to your design, apart from the solid state power supply, was to use a 3.3k resistor rather than a 100 ohm one, the reason behind this was to pull the operating point of the triode down to a lower quiescent current. When measured the supply from the PS1 is 160V and the voltage at the anode is 140V. After prolonged operation the case is only warm to the touch.
 
Once in receipt of all the components assembly commenced, this was largely uneventful and when I plugged it in, it worked well, except for the hum……to cut a long story short I purchased some MuCans, they are not cheap but the results are excellent; the transformers were now shielded and the problem was solved. If you put your ear right in the cone of the speaker you can just about hear it, at 1 metre, nothing. Once the hum was removed I could then really appreciate the abilities of the PreAmp to connect the source to the amplifier without adding or just as importantly losing anything. Looking at the Van der Veen website there are some interesting articles that show why this might be the case.
 
Amplifiers
 
As was indicated earlier I was seeking to Bi-Amp the speakers, the final outcome was that I built a Hypex unit for the bass and bought a Glowmaster Amplifier, it really does stand out as excellent value and I was not disappointed. The main difference to your Glowmaster is the layout and the addition of automatic bias. After searching around the best information on auto bias was again on the Van der Veen website which indicates that for toroidal transformers it is a great benefit. For air gapped, which are less sensitive to DC voltage, there is very little information. What is clearly a benefit is that you just switch on, wait a while and then listen without having to set or worry about the bias. The other upside is that it gives the valves a consistently smooth ride.
 
The difference between using a single amp and Bi-Amping is not as large as others but still very noticeable, bass is well controlled with improved mid and top end clarity. I was also very aware of the difference between voltage control and current control of the speakers by each amplifier. After thinking about it I believe that the impedance of each section of the speakers when Bi-Amped would be nearer 8 Ohms as the connection between the base and mid/top is now broken, this was the setting used on the Glowmaste. It sounded better, however, without the means to measure this it is an estimate based on your original measurements.
 
Other activities
 
Alongside the above I also built a phono PreAmp using the circuit boards from Elliott Sound Products together with Sowter transformers for connecting it to an MC cartridge.  The other activity was to rebuild my very first CD player, a broken Philips CD-104 I had in the loft, where after the griplets were fixed an upgraded power supply, OsCons and NOS (No Over Sampling) were installed. For both of these builds  I was extremely pleased with the outcomes, more detail, transparency and dynamics were heard. There are many websites detailing the changes that can be made to a CD-104 so I will not say any more here.
 
Observations
 
What I very quickly discovered on the internet were the many, often contradictory opinions held. On careful reading and thought it was noticed that many have some truth within them. What guided me on my journey was the following:
 
For the individual system components (Sources, amplification, speakers) a very careful assessment of their individual performance capabilities versus my overall requirements were made before build/purchase
The interfaces between the components selected were crucial, careful matching is necessary here to maximise performance of the next stage(s)
I took a holistic view of the entire system, the sum is what I actually hear, the completed system was a conscious plan that started with the speakers
 
Final thoughts
 
I have a music system with which I am extremely satisfied, the challenge now, for both myself and my wife is to increase our musical experiences with new material.
 
Finally thank you again for your inspiration, information and passion for improvements.
 
Steven