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Siemens CCa (E88CC+) Silver Shield A-Frame Matched Pair w/ BWB Tube - Munich A4 9L/A6 0G - NOS

Siemens CCa (E88CC+) Silver Shield A-Frame Matched Pair w/ BWB Tube - Munich A4 9L/A6 0G - NOS

Regular price $750.00 USD
Regular price Sale price $750.00 USD
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Product Summary

Made for BP (Bundespost - German Federal Post of Berlin) by Siemens, later also approved for military use and various broadcast applications, these tubes carry a long and mysterious history, which might take months to recount. Yet we picky audiophiles approve of their superior qualities...on all accounts: matched triode, low noise screening, minimum 10,000-hour heater life expectancy, carefully controlled frame grid winding and anti-vibration build - this is about as good as it can ever get in the entire vintage tube world! With the unmistakable two-line Munich date code printed on the metal tag, this pair also comes with the famous A-frame construction, the "audiophile version" of CCa!  
What makes this pair so special is the "A6 0G" tube with the BWB military "falcon" stamp - the guarantee of "tested above specs" and high performance. 

Sound Qualities

As a major step-up of Siemens E88CC, the CCa tube naturally posses all the greatest traits of the family: the airy and transparent natural tone unrivaled even to this day, the extended yet never tizzy top end, the incisive, neutral and balanced midrange presentation, the clearly defined and deeply controlled bass that's always there with the perfect amount of weight. All these fantastic sound characteristics multiplied by three and that's what you should expect from the Siemens CCa.  And the most defining sound characteristic of Siemens tubes is their ability to retrieve the deepest levels of detail in sound, and these hidden sonic layers can go a long way to reveal the subtle ambient clues that help complete building a truly 3D holographic sound reproduction. The sound stage of Siemens CCa is amazingly wide and feels like the holographic field gets "flattened" into a panoramic view of your music, still curvy and enveloping, and with added head room - nothing in the sound can escapes your ears (or eyes.) While as quiet and analytical as the Telefunken CCa/E188CC tubes, Siemens CCa's also create a warmer, smoother and sweeter German tone (and very German) that's rarely heard elsewhere. 

Professional Sound Evaluation

The pair worked wonderfully and sounded terrific in our professional studio setup for monitoring. 

 - Input: Cambridge Audio CXC V2 dedicated CD transport + Schiit Audio Bifrost 2 Multibit DAC
 - Amplification: Liquid Platinum Tube Amplifier by Alex Cavalli 
 - Output: Focal Clear MG Pro open-back headphones

Our full tube sound review was written 100% based on the actual listening experience while this pair of tubes were running in the system described above.

Professional testing & sound evaluation

Both tubes tested Super Strong NOS (120%+ mutual conductance) on a Mercury 2000 tube tester with the following result (mutual conductance both in uMhos and in percentage of nominal):

Tube 1: 16,010/16,050 (128%/128%) 
Tube 2: 16,000/16,900 (128%/135%)

Good tubes start at 7000 and new tubes (incl. NOS/NIB) 12,500 - 13,000, and the Mercury 2000's rated mutual conductance (nominal) for new tubes is 12,500. Test result can also be seen in the pictures. In case you wonder what all these numbers mean to your sound experience, it's actually quite straightforward: mutual conductance directly translates to a tube's ability to amplify sound so the higher the numbers the stronger. 

Appearance & Cosmetic condition

At least 90% of the paint and lettering have been well preserved on these tubes. The 2-line Munich date codes printed on the metal tag inside the glass are perfectly visible:

A4 9L (A = CCa/E88CC, 9 = 1969 or Rev. #9, L = December) 
A6 0G (A = CCa/E88CC, 0 = 1970 or Rev. #0, G = July) 
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