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 for. They can make night or day difference in any system. And is not about gain, hence I’m focusing on sharing this blog entry.
Tag: 10
DHT Folded Cascode Experiments
Here we are on holidays and surprisingly I struggle to find any free time in which I can sit down in front of a tablet and write this blog entry. This is actually quite good as it’s a sign of me being disconnected and looking after my daughters. Life is good.
DHT Audio Shootout @ London
Here’s the summary of the shootout day we had yesterday at my place with Tony Rees and Andy Evans
Test Music
For testing the pre-amps Andy suggested the following 2 tracks:
- Ravel Feria (Cleveland/Boulez)
- Janacek The Cunning Little Vixen Act 3 Scene 7 “A vixen’s running through the woods” Prague Theatre/Gregor
Andy Evans
The Ravel is orchestrated for a large orchestra and percussion, and listening was particularly for the timbre of strings, brass and woodwind and the clarity of the percussion. The Janacek is for several different voices and chorus, and listening was for the tone and character of the voices and how well they were differentiated from each other. In both cases the overall clarity, life and crispness was considered.
Although I wasn’t familiarised enough with these 2 tracks myself, I found them to be an excellent choice and a reflection of Andy’s musical experience and knowledge as musician.
Continue reading “DHT Audio Shootout @ London”801a DHT Triode Spice Model
My friend Bela, who is an experienced DHT user and very fond of the 801a, asked me if I could help in developing an LTSpice model for the venerable 801a. I have several 10/10Y but unfortunately no 801a at hand to trace so I used the data sheet curves which are a bit challenging due to resolution/scaling of the characteristic curves:
I had to compromise the model fit as if you want accuracy in A1 region the matching is less than perfect in A2. Still, the model is not perfect but is very good for simulation purposes.
VT-25 / 10-Y triode curves
Everyone loves this thoriated-tungsten DHT valve. I’ve only used it in a preamp and was hooked with its sound. Really warm and nice. Downside is, it’s very pricey these days and also is quite demanding from a filament perspective. You can check the characteristics here.
For those who like testing their designs with LT SPICE, I produced a model which matches really well the traced curves. Would like anyone to use this one, to drop me a note with any feedback 🙂
Here is the VT-25 spice model. Let me know how it works for you!