EML-20A DHT Preamp

Recently I posted about this amazing DHT. Although my original intent was to use them as part of my Parafeed headphone project, I decided to try them as first stage on my system. I have been playing lately with mid-mu DHTs with great success, and this valve didn’t let me down at all.

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ELROG ER801-A Review

I’ve been listening for over a week the Elrog ER801a prototypes. I can say that I’m very please with them. Before I make any further impressions about their sound, let me start from the beginning.

I purchased last year from ELROG (now Deutsche Elektronenröhren Manufaktur GmbH.) a pair of these valves to be used on my VT25/10Y preamp.  I do not own any 801a, but have a good stash of NOS VT25 and 10Y valves. I love this preamp, probably my favourite with the 01a.

Thomas Mayer offered me to send me a preliminary set of prototype valves in advance so I can submit them to the mercy of my tests. That sounded like really good fun and also I thought that the folks out there would be very keen to see the results.

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GM-70 SE Amplifier

I keep getting requests about SE amp designs using the 6SF5 driver. Here is what I have come up with for the 6SF5 driving the GM-70. With only one stage you can drive the GM-70 to full power and get 18W out of this lovely transmitting valve: Continue reading “GM-70 SE Amplifier”

John Cale and the LCO @ Barbican, London

Not many times I write about music, probably I should do it more often. In the end, everything I do here is around and about music, so why not?

I don’t consider myself a music critic, and want to be far from that. Anyhow, I wanted to just share my experience at the Barbican Centre in London this weekend. You may probably know, John Cale played 2 nights with the London Contemporary Orchestra. Cale is one of my favorite musicians. I discovered him back in my youth days when I was a big fan of the Velvet Underground. However, his solo career surprised me and captured me even more. He’s one of the few who continued to evolve, surprise and transform his music over the years. Not an easy thing to do when the majority of the musicians at some point run out of steam in their creativeness and end up in a vicious circle of repeating themselves when they are looking to create something new.

When my wife and I moved to London about 12 years ago, we followed Cale playing around the country. I remember once when we took the train down to Reading. We stopped at a nice pub and managed to get a lovely Mead (which isn’t usual at all) before getting into the concert place. Every time I went to see Cale, he always surprised me in some way.

This time was no different. I went to the Barbican with no real expectation. I said to myself, he’s 76, he may have ran out of steam, as many other ones of his time. However, I was completely wrong and great thing I was! From the first song, I was completely magnetized. Cale dismantled and reassembled the classic songs like never before. Each song was played at different tempo, arrangement and overall song was morphed into something new. Beautiful, not a single miss. The stage was blended with a curious projection of videos on the back of the artists, very well achieved.

I’m not going to mention any of his songs in particular, you can google for the reviews and all the details you want. Just wanted to share what music produces to ourselves when we get close and tuned to the artists. What a night, I went back home with a smile in my face.

Thank you John Cale, Mr. Reed should be very proud of his friend….

Ale

Swenson+ tests with SMPS

Here is a test you might want to take into account. I own an HGC-320-700A SMPS which only allows for maximum current trimming, but output voltage is fixed. In order to avoid unnecessary heatsink, I will suggest using an RC before the Swenson where the R is a big Alu clamped wirewound resistor bolted to the chassis. Just leave 50V for the regulator which may dissipate a lot anyway depending on the output current.
 
There is no caps below and was stable enough. I could have added an output cap but I didn’t on this test. You can see how all the HF noise is trimmed out! About 40 to 60dB 🙂
 
The 44mA and 88mA traces are the SMPS feeding the power resistor directly. 
 
 
This can be improved further with a (mandatory) output cap. A nice 30uF oil cap should do well.
 
I have offered some pairs built and tested to builders using the prototype boards. I may do a couple more if you are interested
 

Another DHT Preamp

Another DHT Preamp on the way with Rod Coleman regs. I will do a A-B comparison with some Tentlabs modules, it’s an interesting experiment to undertake. The preamp has the classic gyrator Rev07 and Source Follower boards…