Clik here to view.
300B SE Amp: build part IX (Layout)
Feedback was that more pictures were preferred. So here they are. I have little time, but slowly I will make progress I hope. The main chopping board is what is left now. Layout is tricky as have not...
View ArticleBa DHT Spice Model
I really love the Ba DHT preamp, if you need the gain in your system, is likely to be one of the best sounding DHT preamps in my experience. As received many requests for the SPICE model for the Ba...
View ArticleClik here to view.
300B SE Amplifier Finished!
When everything was going to plan… This build became one of the quickest and eventually the most painful from all, perhaps not really. However, it was very challenging in the end. I will tell you why...
View ArticleClik here to view.
300b driver experiments
I’ve been enjoying and carefully listening my new 300B amplifier. I have to say that I love every bit of its sound, treble detail and strong bass. The amplifier is fast and can drive very well my...
View ArticleClik here to view.
D3a Spice Model (Pentode & Triode)
My latest 300B amplifier brought me again closer to the D3a. I have to say it’s an exceptional driver for this amp as well as it can perform in a phono stage at same excellent level. I took the...
View ArticleClik here to view.
UX-120 DHT Preamp into 300B
My friend Rob was right. The UX120 sound is unique. Perhaps is due to its cylindrical anode, thoriated-tungsten filament. Anyhow, he was also right that they pick hum and are extremely microphonic!...
View ArticleClik here to view.
300B SE Amp: 46 Driver (Part I)
And time arrived to start experimenting with the different drivers. Why? Well, the whole point of the latest modular design is that I can easily (I hope) make quick changes and experiment. The D3a...
View ArticleClik here to view.
300B SE Amplifier write-up
Finally I managed to get the time to write this up. Hope you enjoy it, you can find it here. 300B Amp in action
View ArticleClik here to view.
300B SE Amp: 46 Driver (Part II)
The 300B amplifier journey continues as planned. A bit lower than expected, however small steps being made. Recently I mentioned about the 46 driver. I made some progress on the LL7903 step-up...
View ArticleClik here to view.
300B SE Amp: 47 Driver
Going DHT end to end As previously mentioned, I played around with the 46 driver. I love it sound and is a great valve. However, there were 2 reasons that pushed me to switch to the 47. Firstly, I...
View ArticleClik here to view.
EML300B Mesh – initial test
My friend Mirek sent me from Czech Republic a few valves for testing, including a pair of precious EML300B Mesh valves. I managed to slot them into my system before departing for holidays. I only...
View ArticleClik here to view.
Pentode driver with feedback (Part I)
It was about time to get my hands on this driver experiment. I’ve been trying to find the time for a while and could only make it due to the obliged COVID-19 isolation upon return from holidays. The...
View ArticleClik here to view.
PP with local feedback: bias PCBs
I’ve been doing some push-pull output stage experiments with either cathode feedback (CFB) via the output transformer (Toroidy custom-made OPT) and parallel-parallel feedback (aka plate-to-grid or a la...
View ArticleClik here to view.
RL12P35 SE Amp – part I
I have plenty of these German WWII pentodes. I’ve been saving them for a few projects. Quite likely for a push-pull amp given the OB speaker project I’m cooking. Either way, I have a nice set of CFB SE...
View ArticleClik here to view.
Fixed Bias Board
Long time ago I built a series variable voltage regulator for 600V. It worked flawlessly and survived all sorts of abuses as is on my bench HT supply. With the same circuit design, I developed the...
View ArticleClik here to view.
EL152 Pentode Spice Model
EL152 Telefunken Some time ago I got hold of a nice stash of Telefunken EL152. These German pentodes are amazing. After playing with the RL12P35P and then obviously GU-50 (which is a copy of the...
View ArticleClik here to view.
SRS551 Pentode Curves and Model
It’s been a long and weird year with COVID-19. This evidently has kept me a bit distracted and changed priorities (as probably has done to you as well). Anyhow, here are the belated curves I was asked...
View ArticleClik here to view.
Mono Amp: EF37a driver (part I)
It’s been a while since I last share some of the experiments. I’ve done a lot with different drivers topologies and pentodes lately, yet not much time to sit down and do a proper write-up. I have a...
View ArticleClik here to view.
Mono Amp: EF37a driver (part II)
On the last post, I shared this great circuit. Now, with the Holiday season and being locked down I somehow find the time to build it. A very quick process as it’s all modular. I’ve got all PCBs that...
View ArticleClik here to view.
Mono Amp: EF37a driver (part III)
After a few exchanges with different people, it was time to make a few tweaks to the EF37a driver. Increasing the G3 voltage helps in squaring up the pentode curves as shown by few before. By...
View Article