Clik here to view.
Stop that oscillation please!
I’ve been playing for some weeks the marvellous UV-201a stage. The addition of the source follower brings a new dimension to this stage. However, I experienced random oscillation on this setup. I...
View ArticleClik here to view.
Ba German DHT Preamp, here we go…
Flying around Travelling around Europe on business is paying its toll. I’m away from home every week and pretty exhausted now. I don’t have much time free and whatever is available I spend with my...
View ArticleClik here to view.
Ba DHT Preamp (Part II)
I’ve been posting not very frequently lately. This is mainly due to lack of time and the level of business travel which reduced to nearly none the time available for DIY audio. Nevertheless, the...
View ArticleClik here to view.
2P29L DHT preamp (again)
Well, after enjoying the 2P29L as part of the Mule preamp project, I decided it was worth building it so I can continue with my adventures on the DHT land. The 2P29L sounds so good that is worth...
View ArticleClik here to view.
Sunday night
It was time for the 10Y DHTs to do their beauty today. Sunday night with good music and single malt. Nothing more can be asked!
View ArticleClik here to view.
UV-201a final version
Top plate arrived as well, so we can put the UV-201a DHT preamp in its final frame. Now it will be time for soldering, yay!
View ArticleClik here to view.
UV-201a final version – finished!
After doing all the soldering part (which I enjoy much), the preamp is now finished. It sounds as good as the original breadboard: For the curious ones, here you have a picture of the inside: The...
View ArticleClik here to view.
4P1L / 4П1Л Siberian Gen4 in Screen mode (part 2)
Last time I wrote about the 4P1L in screen mode. It was great to see some DIYAudio member (Blitz) to post about his work on the 4P1L with screen as anode. I call it screen mode but probably is...
View ArticleClik here to view.
2P29L DHT Preamp – final build
Finally I managed to build a stable version of the 2P29L preamp. The wooden modular version inspired on DHTRob designs paid off. Here it is: The result is fantastic. The 2P29L is a superb DHT, quiet...
View ArticleClik here to view.
Screen supply with VR valve
If you like your VR valve glowing in the dark but you’re concerned about how quiet it will be, then you may be interested in this post. I like the VR, I used them a lot. They are quieter than most...
View ArticleClik here to view.
01a Preamp build by Paul
Here’s an excellent build of the 01a Preamp with the gyrator PCBs and the Source Follower PCBs by Paul. I will leave to him to write down his impressions of this preamp and the build experience.
View ArticleClik here to view.
Flexible CCS board prototype
I’ve been prototyping a flexible CCS PCB. The intent is to provide a cascoded FET pair with some interesting features: The lower FET can be multiple devices depending on the choice of reverse...
View ArticleClik here to view.
eTracer Build and Review
Tracing valves: an obsession Since my early days of valves and DIY audio, I developed an obsession around testing and tracing valves. This led me to design and build my analogue curve tracer which I...
View ArticleClik here to view.
A tale about DHT Supplies
I’ve been using my choke-input DHT filament supplies for many years. I’ve got many of them as you’d expect. Something I do really hate is to build power supplies. It’s dull and boring, but they’re a...
View ArticleClik here to view.
Tail CCS PCB prototype
Recently I’ve spent some time designing some PCBs for my own use and why not to share them as well to the DIY audio community. Currently I have a flexible CCS board for anode loads and a tail CCS,...
View ArticleClik here to view.
EML 20-AM DHT curves and model
There is one DHT which attracted me from Emission Labs which is the EML20. If you’re looking for a mid-mu DHT valve these days, this one is the way to go. In order to meet with the two key requirements...
View ArticleClik here to view.
Swenson+ HT regulator test
So the developing is progressing. This time I tested the first PCB prototype of my enhanced “Swenson” regulator which I baptised Swenson+. It’s a great circuit and performs really well. Although...
View ArticleClik here to view.
300B Un-bypassed Rk Bias Line Stage
Many times I get emails from DIY Audio builders who embark on building a DHT preamp when they don’t need gain, but instead what they need is a simple line stage to drive their amplifiers and...
View ArticleClik here to view.
Valve test rig with fixed bias
My test rig for DHT/IHT stages (and even Pentodes) has evolved over the years. Lately I settled with some nice modifications to allow testing the majority of valves I have. I use a modular socket...
View ArticleClik here to view.
Emission Labs 20AM: first tests
After tweaking my test rig to fit a variable supply for fixed bias, I proceeded with the tests with the EML20AM valve. After playing a bit today with the valve, found that it picks up hum like the Ba...
View Article