September 23, 2012
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AEG CCa and Siemens E188CC
Today’s review takes us to Germany and, specifically, to small signal tubes manufactured by Siemens. The subject tubes are the AEG CCa 6922 which was used as the input tube in the Premier 140 and six Siemens ECC188/7308’s in the Premier 16LS2 preamplifier.
AEG is an acronym for Allgemeine Elektricitäts-Gesellschaft which is German for “the General electricity company” and the competing radio companies AEG and Siemens & Halske merged back in 1903 to form the subsidiary company Telefunken. On January 1, 1967 AEG and Telefunken merge to form the not very originally named AEG-Telefunken. Sound confusing and more than a bit incestuous? In any event, based on its construction which includes a four-seamed top and a silver production chad bearing the imprint:
A6 (Siemen’s designation for a 6922)
0B (1980 production)I’m going to say with some confidence, this is a Siemens 6922. The CCa is a subgroup from general production (typically around 15% of a batch) that was selected for low noise and close triode matching and ear-marked for the German postal service (telephone, telegraph, telex, and the postal system).
The Siemens E188CC tubes in the 16LS2 also bear a silver chad with the imprint:
G6 (Siemen’s designation for an E188CC/7308)
8B (1978 production)AEG CCa AEG CCa Rear View
Siemens E188CC Siemens E188CC Rear View
Siemens E188CC Bottom View Siemens E188CC Top View
As a point of information, some vendors say that the later production Siemens ECC188/7308 (late 70’s and 80’s) sound nothing like earlier production and should be avoided because they sound harsh.
You take what you can get. One other bit of information, the Siemens E188CC’s produced a tinging sound out of the left channel speaker at times (especially when cold) when volume changes were made on the preamp. As far as I could tell, however, they were not microphonic while music was playing.
This set of seven tubes replaced an Amperex pinched-waist 1958 US production 6922 that had been in the Premier 140 and Amperex small O-ring 6DJ8’s from Holland that were marked HP (Hewlett-Packard) in the 16LS2. In other words, they had their work cut out for them.
Total playing time for this configuration was 54 hours.
Listening Impressions:
- Bass is tight and well-defined with no booming qualities.
- Impactful sound with reference level macrodynamics.
- The overall sound quality leaned towards the analytical with a lack of the Amperex’s vaunted smoothness and refinement. It could almost be described as more solid state than tubular.
- Frequency response is even across the spectrum but with a little glassiness in the lower/mid treble.
- The sound stage started in a plane farther behind the speakers compared to the Amperex configuration, although it projected well into the listening room as is characteristic for my system.
Changes made to the system which included power cords, speaker cables, aftermarket fuses, and new phase splitter tubes in the Premier 140 while this configuration was in place were consistently audible. I take that as a very good sign.
If your system currently leans a little to the dark side of neutral, these tubes may offer you a useful fine-tuning option.
Comments (4)
Beautiful!
what is your fave tube in your C-J gear?
It's funny, but since I've had the Teflon capacitor upgrade done to the Premier 140, my opinions are changing. At this point, I'd have to say that my favorites would be the stock configuration of 6922EH in the Premier 16LS2, 6922EH as the input tube in the Premier 140 and the SED =C= 6550C power tubes. The only change from stock would be the 6H30π-DR in place of 6H30π-EB as the phase splitters.
@JAFANT -
I'd have to add what's in the system now to my above choice as an also favorite: Voskhod 6H23π-EB in the Pr. 16LS2 preamp and the Pr. 140 as input tube, 6H30π-DR as the phase splitters and vintage Tung-Sol solid grey plate 6550's. I've been listening to this configuration all day and it's right up there at the top.
Very nice JDA!