Clik here to view.
01a Low Gain DHT preamp
How many times I’ve been asked “how do I lower the gain of the DHT preamp?” many builders love the DHT sound and yet don’t really need that gain. Of course when you use a transformer load, step down is...
View ArticleClik here to view.
300B/845 Amp: Driver Options
For more than 6 months I’ve been playing with a lot of satisfaction my 300B amplifier with the 47 driver. Since then, I’ve made 2 modifications: Major one was the introduction of my Open-Baffle (OB)...
View ArticleClik here to view.
01a Low Gain DHT preamp (finished)
It was a half-hour job to mod my Mule preamp by swapping out the UX-120 and introducing the 01a (CX-301a in fact), add the resistor divider to deliver low gain on this preamp: 01a mule I set the valves...
View ArticleClik here to view.
The low gain DHT pre-amp library
For more than 10 years I’ve been experimenting, designing and enjoying DHT pre-amps. Without over-dwelling on this subject, to me DHT preamps bring the unique sound transparency and detail we all seek...
View ArticleClik here to view.
801a preamp build
I wanted to share a nice review provided by Lionel Borcelot on his journey in building the VT-25/10Y/801a preamp as shared previously. I think this is a good example on what to expect and how to...
View ArticleClik here to view.
845/813 SE Amp: And the iron is here
I’ve received several emails from people asking me why I’ve gone quite lately. Nothing to be alarmed, I’m just simply buried on the daily grind like many out there are on these Pandemic times. My...
View ArticleClik here to view.
LL1943 SUT PCB V02 – Balanced option
After a long time, decided to update the PCB of the LL1943 SUT to provide extra flexibility on the grounding connection. This is in essence to ensure no ground loops and noise when either using...
View ArticleClik here to view.
FT-3 Coupling Cap PCB
As several DIYers out there, I’m a big fan of the Russian teflon FT-3 capacitors in my preamps. I normally use the 220nF/600V ones as have plenty of them in stock. These are superb in my view, however...
View ArticleClik here to view.
EF86 – 300B XLS SE Amplifier build
Here is a very nice build from Dan Kercher on his contraption of the 300B amplifier with auto bias. The driver is an EF86 with SiC diode biasing, the topology is a hybrid mu-follower and a source...
View ArticleClik here to view.
DHTs and cathode bias degeneration
A few years back I went down the path of exploring different DHT in pre-amp stages for sonic improvements on detail and dynamics. I explored all sorts of different DHTs as have posted in the blog and...
View ArticleHT Supply PCB
I added these PCB for sale. I made a small batch for my own use (you can see them in the 300B amplifier here) but am selling the rest of them.
View ArticleDHT Supply PCB
I took me a couple of years but eventually found the time to build the BOM and a simple documentation guide for the DHT LT supply PCB. I’ve been using this PCB for a long time on most of my DHT preamps...
View ArticleClik here to view.
801a preamp revisited (part I)
It’s been a long since I last posted here some project stuff. I’ve been busy with work and family. On my spare time, spent mostly listening to music, developing some synthesiser modules and playing...
View ArticleClik here to view.
01a Preamp by Nash
It’s always satisfying to see someone else enjoying the end result of their build work. Here’s a great example of Nash building his take on the 01a low gain DHT pre-amp: Hi Ale, Its now over two...
View ArticleClik here to view.
Aa DHT Spice Model
About 5 years ago I built the first version of the Aa DHT preamp. It looked like this: This preamp sounded great (as you would expect with this DHT valve). As wrote before, with a gain of about 30 is...
View ArticleClik here to view.
24 Driver
About 10 years ago I used this tetrode driver which I loved. The 24. It has hungry filaments, albeit a lovely sound. I probably lost a few readers by now, but don’t care. The 24 into the 45 Single...
View ArticleClik here to view.
1624 feedback SE Amp
Long time ago I breadboarded the 1624 valve and liked the sound. The 807 is famous and I never ended up with a permanent system with this valve. Yet, I like it. And if you have them at hand, use them....
View ArticleClik here to view.
811a SE Amplifier with a twist
Goodbye Jon Sadly, yesterday heard the sad news that our friend Jon Finlayson from the London Audio Circle passed away. Jon was an incredible person, a true music lover and passionate about life. He...
View ArticleClik here to view.
6P36S Mono SE Amp
Brief post of a very long experiment. Unfortunately I’d have to dig out a long list of notes, tests and simulations to get the full thing out there. Unfortunately due to constraints, this will be brief...
View ArticleClik here to view.
Bartola Valves Book Scam!
It’s been long since my last post. Life is busy for me these days, so not much time free for Audio work. I managed to rebuild my listening room after nearly a year of disruptive and delayed building...
View Article