Yarland/Ariand Class A Tube Amplifier Thread

[bkatbamna]

If you want to use 2 different pre-amps and amps, you don't need a switcher box for inputs or for speakers. I have y-connectors going from both my pre-amp outputs to both my amplifiers and then 2 female to one male banana plug connectors going to the speakers. As long as only one amp and one pre-amp are on, there is no problem as long as the speaker inputs are insulated from each other.

Available from Amazon, just make sure the speaker connectors going into these adapters don't short.

 

[mhardy6647]

^^^ At loudspeaker level, that is so not a good idea.

A line-level splitter is OK; a line-level combiner... not so much.

 

[bkatbamna]

I've been using that set up for a long time. But, I make sure the amplifier that is not being used is unplugged while using the other amplifier. And of course, the speaker connectors are insulated and separated from each other so they cannot short out.

 

[Xulonn]

My YarLand EL34 amplifier is working fine, and the heat of a mid-power Class-A vacuum tube amplifier helps a bit with the evening chill. It typically reaches a high of about 80°F/27°C during the day, and sometimes drops as low as 60°F/15°C at night here in the mountains of Western Panama. Brrrr.... So chilly, in fact, that I actually have to put on a long-sleeve shirt in the evening! (Those are year-round temps - no four seasons weather here in the tropics at 8°N latitude!)

But I digress. The amp is still sitting on a console table next to my desk while I wait for the arrival of a printer stand (pic below) and XLR Cables from Amazon, and a "two amplifiers to one pair of speakers switch" from AliExpress. The stand will be a temporary location for the amp and step-up transformer until I finish the design and have a proper media stand built. The new media stand will hold my A/V electronics, L/C/R speakers, 40" Samsung LCD TV, and some art pieces and books.

I am still listening to music via MoOde on my RPi and the Yamaha NS-A325 mini-monitors - which are only rated down to 150Hz. MoOde is a Digital Audio Player, so even though it can play in internet music streams, you cannot browse to a website and select test tones to play. So I downloaded some MP3 frequency test tones (from TestTones.com) to roughly measure bass response, and discovered that the tiny Yamahas are still clearly audible down to 100Hz, but inaudible at 60hz. Some music - especially music with mostly electronic instruments, including rock and some jazz, is not enjoyable with such limited bass. OTOH, a lot of acoustic music still is quite listenable. I will be happy when everything I ordered arrives, so I can hear the YarLand via my Wharfedale speakers.

 

[Xulonn]

There's been a big change in my final configuration plans. My current main system is primarily a video configuration that I also use for music, using LibreELEC/Kodi on an Intel NUC3 which feeds an IOTAVX AVP via HDMI with XLR out to my Ghent/ICEPower amplifiers, which drive my L/C/R Wharfedale 300 series loudspeakers.

When @amirm tested the Topping DX7s a couple of years ago, and it became available for a good price via Drop, I bought one, planning on getting headphones for the first time (which I never did). Then I moved to the AVP and HDMI, and set the DX7s aside I had almost forgotten about it as it was sitting on a closet shelf.

A few days ago, I realized that the DX7s would be a perfect solution for integrating my YarLand EL34 vacuum tube amplifier into my system. I realized that I could send audio from the MoOde/RPi player to the DX7s via USB, and then the line-level output to the YarLand via XLR balanced. Speakers can be switched bettween amps, and with separate sources, no source switch is necessary. Such a configuration allows a high fidelity stereo audio system to work side-by-side with an optimized video/HT system.

Compared to MoOde, Kodi is quite complex and a pain to navigate to and then play MP3 files - and it also has a very limited and poorly implemented headless operation. Kodi's primary mission is to play movies and videos while sitting in front of a TV, and I will continue to use it for thatas well as for music videos.

My MoOde/RPi, OTOH, is a dedicated headless music player that can be used with no direct connection to a screen and keyboard. It is controlled via a network IP connection from my Wndows 11 PC, or from my Android tablet or smart phone.

The only issue of concern is accidentally leaving the vacuum tube amplifier on when switching the speakers away from it. Apparently that can cause problems for output transformers and possibly lead to serious damage to tube amplifiers, but switching between tube and SS amplifiers is something that I and others want to do. ASR member @Blumlein 88 told me that a 220Ω/5w resistor across the tube amplifier speaker outputs would alleviate the "no-load" output transformer problem and not affect sound. I will explore that issue further in another thread so people can find it more easily in the future if they have similar concerns.

 

[Blumlein 88]

There's been a big change in my final configuration plans. My current main system is primarily a video configuration that I also use for music, using LibreELEC/Kodi on an Intel NUC3 which feeds an IOTAVX AVP via HDMI with XLR out to my Ghent/ICEPower amplifiers, which drive my L/C/R Wharfedale 300 series loudspeakers.

When @amirm tested the Topping DX7s a couple of years ago, and it became available for a good price via Drop, I bought one, planning on getting headphones for the first time (which I never did). Then I moved to the AVP and HDMI, and set the DX7s aside I had almost forgotten about it as it was sitting on a closet shelf.

A few days ago, I realized that the DX7s would be a perfect solution for integrating my YarLand EL34 vacuum tube amplifier into my system. I realized that I could send audio from the MoOde/RPi player to the DX7s via USB, and then the line-level output to the YarLand via XLR balanced. Speakers can be switched bettween amps, and with separate sources, no source switch is necessary. Such a configuration allows a high fidelity stereo audio system to work side-by-side with an optimized video/HT system.

Compared to MoOde, Kodi is quite complex and a pain to navigate to and then play MP3 files - and it also has a very limited and poorly implemented headless operation. Kodi's primary mission is to play movies and videos while sitting in front of a TV, and I will continue to use it for thatas well as for music videos.

My MoOde/RPi, OTOH, is a dedicated headless music player that can be used with no direct connection to a screen and keyboard. It is controlled via a network IP connection from my Wndows 11 PC, or from my Android tablet or smart phone.

The only issue of concern is accidentally leaving the vacuum tube amplifier on when switching the speakers away from it. Apparently that can cause problems for output transformers and possibly lead to serious damage to tube amplifiers, but switching between tube and SS amplifiers is something that I and others want to do. ASR member @Blumlein 88 told me that a 220Ω/5w resistor across the tube amplifier speaker outputs would alleviate the "no-load" output transformer problem and not affect sound. I will explore that issue further in another thread so people can find it more easily in the future if they have similar concerns.

This link might be useful in the thread you start.

https://dalmura.com.au/static/Output%20transformer%20protection.pdf

Detailed explanation about what happens with unloaded vacuum tube output transformers and ways to protect them. The resistor idea is around the middle of this article on page 8. I don't know where I first encountered it, but it was years ago, and it works.

Some will say you don't need anything, but they've just been lucky. No load with no signal will sometimes be okay for a few moments (sometimes not). If you have no load with any substantial signal bad things will happen.

It is also possible to protect them by putting a resistor on the primary side of the transformer. I forget the details, I think you need a fairly small value. What happens is without a load voltage goes to max plus an inductive kick and shorts/arcs the windings.

 

[LTig]

This link might be useful in the thread you start.

https://dalmura.com.au/static/Output%20transformer%20protection.pdf

Detailed explanation about what happens with unloaded vacuum tube output transformers and ways to protect them. The resistor idea is around the middle of this article on page 8. I don't know where I first encountered it, but it was years ago, and it works.

Some will say you don't need anything, but they've just been lucky. No load with no signal will sometimes be okay for a few moments (sometimes not). If you have no load with any substantial signal bad things will happen.

It is also possible to protect them by putting a resistor on the primary side of the transformer. I forget the details, I think you need a fairly small value. What happens is without a load voltage goes to max plus an inductive kick and shorts/arcs the windings.

You've just beat me, I was going to intervene as well. Would be a real pity if he blows his new amp in such a way.

 

[Xulonn]

An aside on my adventure with trying to use a HiFiBerry DAC Pro+ and why it didn't work with Volumio or MoOde:

Although I had great expectations, my experience with a HiFiBerry product is mixed. I have a 3-year old RPi3b+ with a HiFiBerry DAC Pro+ hat housed in a metal HiFiBerry case. I used it for showing movies in an expat community theater a couple of years ago, and I dragged it out of my closet to use with my new YarLand amp. With the movies, I used OSMC, a Kodi variant, on the RPi. I fed the video output to a projector via HDMI, and the 2-channel audio to the side-stage mixing panel via the HiFiBerry's RCA outputs. Everything worked great - it was a pefect application. Then the movies were shut down when Covid hit and social restrictions were implemented here Panama. (Since then, the stage/backstage and 100 chair seating and risers have been ripped out due to serious pest/insect problems and the room converted to other uses in what is now a restaurant/sports bar facility.) The RPi sat idle in my closet until this week.

With the YarLand amplifier, I was interested in a pure headless DAP/DAC setup for music, separated from my video/HT system. So, as I have etioned before, I will use a speaker switcher on the L/R Wharfedale speakers to break them from my 3.0 (L/C/R) Kodi/IOTAVX AVP/ICEPower system.

I believe that an RPi3B+ is an excellent piece of source hardware, so I pulled the MicroSD card out of the RPi and installed Volumio on it. It worked and the interface looked normal, but unfortunately, all I got out of it was white noise with the audio faintly audible buried way down in the noise. So I tried MoOde and got the same result. After hours of trying everything I could think of, I assumed that there was a problem with the HiFiBerry hardware or firmware. So I gave up and inserted my backup DAC (an S.M.S.L Sanskrit 6th) in the chain via USB from the RPi, and now everything works fine. (When my XLR cables and other hardware bits arrive, I will replace the S.M.S.L. Sanskrit with my Topping DX7s.)

I didn't like Volumio's features and interface - and it is buggy. Fortunately, MoOde works perfectly - and I like the interface. A nice feature is that it seems to automatically update only the current folder you are in when doing a Library Update after adding or removing some MP3's. By not re-indexing the entire library on updating, you can add some files to your NAS or local drive, and play them within a few minutes rather than waiting hours for a full library update. I have a rather large (30K+) MP3 music library, and the MoOde update algorithm saves a lot of time.

It is my opinion that an RPi3+ is adequate for a true high-fidelity digital source that can be used use to play local or NAS files or internet radio, and I can see no reason to use a more expensive desktop DAP. But I do recommend using an external DAC/ I have no desire to use any HiFiBerry product in the future due to both my problems plus their lackluster showing in the measurements performed here at ASR by @amirm.