Lyrita 2A3 with directly heated triode 45 tube as driver

[Rajiv]

Hi,

It has been a while since I have posted about my system. Mainly because there has been so significant change to the system.

My primary system is based around the Lyrita 2A3 amp and Lyrita DHT pre. Speakers are a DIY effort using Altec 515B woofers in a half horn cabinet,RCA 9584 midrange driver with Lyrita 400hz LeCleach horn,tweeter is a Pioneer/TOA HW7.

TT in current use is the Garrard 301/SME 3012/Ortofon SL15 or Linn Karma.(plinth is an experimental design) Phono stage is the Lyrita MC phono stage. Digital is served by a PC with Juli@ sound card.

Over the years I have incorporated the upgrades to the Lyrita amplification chain on Viren's suggestion.

A couple of months back Viren called and said that he had been experimenting with directly heated triodes as driver tubes in the 2A3 amp and the improvement in sound quality was significant.

My amp made the trip to Delhi and back for Viren to incorporate the modifications. The stock Lyrita 2A3 is no slouch and has easily bested many amps that are far more expensive. The change of driver tube to the 45 which is a directly heated triode has taken the sound quality to a whole new level.

Music sounds real and instruments and voices sound "organic". The overall sound quality has improved over the entire spectrum.This is the most significant improvement to the system in quite a while. Thank you Viren for all your help and advice over the years.

Members are welcome to listen to my system.

Regards
Rajiv

 

[Rajiv]

Hi,

The pictures did not upload with the previous post.

Regards
Rajiv

OOPS! How do I get them right side up?

 

[GeorgeO]

Great Rajiv!

 

[captrajesh]

The change of driver tube to the 45 which is a directly heated triode has taken the sound quality to a whole new level.

Music sounds real and instruments and voices sound "organic". The overall sound quality has improved over the entire spectrum.This is the most significant improvement to the system in quite a while. Thank you Viren for all your help and advice over the years.

Members are welcome to listen to my system.

Congratulations Rajiv. A reason for me to make a trip to Chennai soon.

 

[prem]

Great to hear about this upgrade Rajiv. It's something I always wanted to experiment with when using the 2a3 amp but never got around doing it.

 

[Kushanava]

What is the output wattage ?

 

[Rajiv]

Hi,

The amp can use both the 2A3 and the 45 in the output stage. With the 2A3 tubes the output is about 2.5 to 3 watts. With the 45 tubes in the output stage the power output is around 1.5 watts.

Regards
Rajiv

 

[sunder]

What would be the sonic differences between if we use the separate Lyrita DHT preamp with 2A3 amp and another preamp with your modified 2A3 amp, Rajiv? It excels only with Lyrita DHT preamp? Thanks.

-Sunder.

 

[viren bakhshi]

Ah, some insights into the new circuit are in order, I think.

Just like in an audio chain, all components determine the overall sound, the earlier ones having an equal, or more, influence. So to in the amplification stages of a tube amp. In the Lyrita 2A3 SET power amp, the driver tube sees the signal first before it reaches the 2A3 output tube - so, in essence it's only half a DHT amp. To make the amp all DHT, the driver tube has to be one too, and the 45 tube serves admirably. You get the full tonal colour that only DHT tubes can provide, and a realism to music that has to be heard!

Of course, to make the entire amplification chain all DHT, the preamp has to have one too. The Lyrita DHT Line preamp serves here.

And, there is no free lunch! The 45 tube as driver just doesn't have enough gain, so another gain stage is required in the amp. Can't defeat the intent of an all DHT setup - so an input transformer is used to provide the gain. Now, not only do we have an all DHT amplification chain, it is also all transformer coupled. Nary a capacitor in the direct signal path!

In my opinion, transformers are the most benign out of all components in influencing sound. The entire chain then contributes to a very dynamic, live sound.

Regards,
Viren

 

[sunder]

Thank you Viren ji. But, the speakers with very high sensitivity will be needed since the output wattage is below 2W. Thanks.
Sunder.

 

[amit11]

Recently I started taking interest in SET amps. I came across one article which was mentioning the sensitivity of speakers required vs the SET amps wattage. I have attached one screenshot and highlighted that section. Might be useful.