After a complete change of career, around 5 years ago, I didn’t had much time to invest in hobbies anymore. The limited free time I had was invested in learning more about pedagogy. This is Slowly changing, returning to more reasonable schedules at work, and I recently started playing with audio related projects again.
During that period of transotion I lost interest in social medias, forums and blogs … But I did manage to do some improvements to my audio gears and here they are :
A new amplifier for the mid horns
Since 2016 2017 my only “big” project has been to build a small tube amplifier for my mid horns. It’s a simple, but overkill, el84 in single ended triode configured and driven by a 6n1p. I only used high quality components that I had laying around (ex : audionote power xfo, james 6123hs outputs, elna cerafin in a LCLCLC-C configuration after hexfred diodes) etc. It’s a huge amplifier considering it output only 2 watts per channel … while consuming a 50 watts from the outlet. It sound fantastic when used full range but I’ve limited the frequency range to 100hz and up. The reason been that it will only be used only for mid-range. In my current application, the amplifier cover from 370hz to 2khz.
Going from icepower to a small tube amp completly opened up the mids and brought back a level of information missing. I tried going back to the icepower in the next summer (to limit exelectricity consuption when running the AC unit) and just couldn’t live with the icepower on my mid horns anymore. The first D class amplifier from my system was gone.
Adding new beyma tpl-150 in JMLC horns
I wanted to get rid of the raal for some time and after trying diffretent solutions, a friend sold me a pair of beyma tpl tweeters. They are fitted to small JMLC horns. I was curious to see how well they would work with my mids.
In my system the synergy with my larger JMLC music concrete horns is fantastic. The efficiency, dynamics and tonalities are a huge improvement compared to the small raal. The raals did a good job from 10khz and up but couldn’t match the livenes and dynamic range of the horns so they forced my to use a high crossover point and get some directivity in the mid range.
While Amazing from 2 khz to 10khz, the tpl didn’t cover the 10 khz to 20khz as well. For me, the 2khz to 10khz is a lot more important than the 10khz and higher. Later I got a NOS pair of coral horn tweeters, in a swap meet, for a ridiculously low price and brought them home hoping they would be efficient enough to be used over my tlp-150. After some measurement and trying different ntegration point, I’m now using them from around 10 khz to whatever they can give . They go up to around 20khz and match the efficiency of the beymas quite well. It sound nice enough and I don’t miss the raals for the 10khz plus anymore. Eventually I may try replacing the corals for a pair of visatoon tl16h. I really like their frequency response measurements published on a French audio forum.
I’ve bean listening to those two tweeters together for over a year now and still enjoying it.
Fast forward to 2019
Late 2019 I got a chance to purchase back my old pair of SETH PP 2a3 amplifiers. I had the pair home around 2010 and after couple or years, I sold them needing more power. I always regretted selling those, fearing that one day I would get speaker efficient enough to use them. The amps resurfaced on the used gear market and spotted them while I was searching for parts to build something similar. Finding permaloy transformer and nickel interstage and chokes is not easy task now and it’s really expensive.
The SETH PP 2A3 magnequest amplifiers are a design of Jean-Francois Lessard that was published on magnequest web site some time ago. It’s a DIY poject published for free and you can find the parts around the web. The 3 transformers and 3 chokes per mono block , using magnequest nickels parts made the project very expensive and few have built them. The result extremtly good and completly noise free (a must for my 103 db eff tweeters). It’s a push pull of triode using no feedback at all, and a center tapped choke specifically made to be used as a phase splitter.
I bought the amplifiers back, removed the Chinese tubes on it and installed a fresh pair of 2A3 sovtek tubes. The amplifiers are now used from 2 khz and up (tweeters) replacing my old icepower 125asx2. Since I cross my tweeters quite low, at 2 khz, the amplifiers sound quality is very important. This change helped a lot when matching my mids and highs horns seamlessly. This change brought me closer to the music and turn out to be an important one.
A second D class amplifiers was gone
Removing the back caps of my JBL 2440 with radian diaphragms
A simple test of measuring the horns with and without the back caps of the compression drivers revealed a nicer and smoother frequency response when removing the back cap. Since my horn loaded beyma are also di-polar, I simply installed some heavier shades behind the speakers and I’m now having the diaphragms completely exposed on the back.
The drawback of doing so is that you have expensive diaphragms completly exposed on the back of the compression drivers.
Now, if you want to visit me, you need to sign a mendatory weaver stating you wont put your fingers in those radian diaphragms 🙂
One way was still using D class amplifiers
The last D class amplfier standing was my custom made pair of icepower 500asp. The 2 mono blocks power my visaton tiw250xs woofers. Considering that removing the other icepower amplifiers made me enjoy more and more my system I was curious to know what would be the result of replacing those 2 mono blocks by something with similar power while been A classe or AB classe.
It’s not easy to find a 500-600 watts tube amplifiers and I didn’t want to manage a farm of high power tubes so I was fixed on transistor for this way. I started reading about different type of amplifier and was looking for either Krell, Passlabs or Bryston monoblocs.
In the last days of 2019 I’ve been lucky to find a deal on a nice pair of bryston 7b3 (or 7b cubed) mono blocs. These are demos from a local retailer I often do business with called Solen (www.solen.ca) and got what is pretty much a brand new pair of fully warranty covered amplifiers. It’s a very expensive upgrade but after reading a lot about the bryston’s cubed serie it seems to be a departure from their older sound which I wasn’t specially a fan of. The new sound is more on line with what I like.
Bryston is a Canadian company with an amazing warranty. These two points helped to take the decision. I wasn’t looking for the most powerfull amplifier at 2 ohms (or 1 ohms) but to get over 500 watts at 8 ohms. They also need to sound good even on a small full ranger driver pushing low power or in other words, the first watt need to sound very good. The 7b3 mono blocks fitted the needs but at a cost, a high one. I bought them.
My 7b3 are delivering 677 watts in 8 ohms (manufacturer test sheet), my soon to be redesigned bass cabinet will now use 4 visaton tiw250xw and 4 externally adjustable passive radiators per side and this configuration will result in 8 ohms instead of the 4 ohms I’m now getting. This mean my 500asp would had went from 500 watts to 250 watts per side. Compare this to the 7b3 I go from 250 watts to 677 watts and from 2 drivers to 4 drivers per side. I’m pretty sure the efficiency and power will make my bass cab closer to match the energy I get from the horns. Anyway, right now at 500watts in 2 drivers per side it’s very impressive for the reality of my home and room so it can only be an improvement.
I had to install my 100 pounds 70″ lcd screen on the wall in order to make room on the top of the audio rack for the amplifier. I also had to bring a dedicated electrical circuit just for the amplifiers.
I got the amplifiers home today and did a quick replacement and gain adjustment to do a first listening session and so far so good.
It’s another layer of veil lifted and my low mid are more detailed and energetic. Everything is new and I have to take more time to fine tune the integration in my DEQX but just matching the gain was enough to convince me I went the right way by removing the last D class amplifiers from my system.
I will have to take some times to listen and compare before having a final idea but so far I can’t see a negative side while enjoying the impeovements.
I was afraid the bryston wouldn’t control the woofers as well as the icepower asp series of amplifiers but it’s not the case. The bryston have no problems on this aspect. So far I would say the kick drum punch more with the brystons and sub bass is solid and free of distortion.
It’s not over
Next step is finally making my version two of the bass cabinets doubling the drivers from 2 to 4 per side and also doubling the number of passive radiators.
Basically, each cabs will be 4 independent cabinets for a total of 8. This project should start in February and hopefully be functional this summer.
My actual cabinets are poorly made proof of concept using thin plywood and no bracing and even then they are very enjoyable. I have huge expectation for this anyway since I will raise efficiency, lower the distortion a reduce cabinet resonances.
I did take a break of improving my system for some years and took time to do other hobbies (photography, cycling, mechanics on my old car, work …) but during that time I never stopped using my sound system and was enjoying it a lot. When I’m home, there is either music playing or a TV series playing. I work often from home in my new career and can really enjoy siting on my computer desk while having nice music playing. My sound system is a very important part of my life.
I wouldn’t say the D class amplifiers that I replaced where bad, in fact I was quite happy using them for many years. There is always something better but the complexity and/or price to to get it can be a huge barrier. If you are willing to go the extra miles it can be rewarding but it’s costly and complex in my case.
Those last changes made my sound system more enjoyable and brought me closer to music.
The biggest change is when listening at low or medium sound level. It used to be a little flat and dead compared to when pushing it. replacing the amplifiers for class A on mid and highs and a quad something bla bla AB class from bryston removed that problem and I can feel the energy of the instruments without having to get to unreasonable spl. At higher spl there is also a good gain in realism and accuracy.
It’s, in a way, a huge change for me. Would someone that listen to my system only from time to time feel the same way ? … will see.
What’s next ?
- Building and finishing the bass cabs
- Making a for of stand to place the horns over those bass cabs
- Changing the driver section of the SETH PP 2A3 amplifier to the mkII version using a 6H30 tubes (I just got all the parts for this)
- I would like to try a pair of visaton tl16h instead of the coral horn tweeters for 10khz and up
- I wand to change my mid amplifier coupling from the driver stage to the el84 with a pair of lundhal inter-stages transformers
- Improve the digital source, testing other solutions to my hifiberry digi out
- And other things for sure
Thanks for visiting my blog, I will try to post the next projects when they are done.
A good 2020 year to all !
Edit : I took some time to rearrange my components in the audio rack so it’s all contained and no amplifier has to sit on the ground.
Here is the new arrangement :