Standard 33S29B / 5691 Sweden

Standard 33S29B / 5691 Sweden
Military spec, heavy duty construction 5691 made by Standard in Sweden 1950s under license of RCA. ULTRA RARE!!! One of the best 6SL7 ever made just like her sister 6SN7 equivalent 3S30B/5692. This tube has dark brown base, triple mica, black plates, double D-getter and 5 support rods. Our huge stock is labeled and boxed as 6SL7WGT/Haltron, the reliable British company. Please see below for the reference pictures to compare. Nowhere else on the earth available in such a large quantity! Matched pairs and quads available.

Quantity in Stock : Out of Stock!
Price : US$ 0,00/each ; US$ 0,00/matched pair                 

Grade A - The best in the stock. Lowest noise and microphony with the tightest balanced sections we have available. This is typically 10% or often tighter given the large volumes of our stock.
Grade B - Low noise and microphonics with a section balance typically between 15% and 20%, but may be higher depending on available stock.
Grade C - Lowest noise but slightly microphonic. Section balance will be similar to Grade A or B. This grade is only suitable for use in the driver stage of an amplifier, or the output/buffer stage of a DAC or CD Player.


  1. Exceptional sound: warm, smooth, perfectly balanced with a lot of dynamics. Adds depth and stereophonic space resulting in improved listening pleasure though the previous tubes I had were good NOS 6SL7WGT. Well worth the expense. Once again,an excellent advice from Koray !
    Serge Bottari

  2. Hi Koray,
    I received the Haltron they were excellently packed. They have had a few days running in and they already sound outstanding. These are easily the best sounding 6SL7 I have ever heard.
    Thanks Dean - Australia


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