Soundlumia's Opinion

The beauty, the legend, the classic, the Special Quality(SQ) - this is the super tube from Heerlen's high echelon that doesn't break the bank. Known for their superb musicality and ultra low noise, thanks to Philips' proprietary SQ design, these tubes remain among audiophiles' top choices for critical listening. 

Immediately appealing is the super smooth highs offered by these tubes with lots of open air. The overall tonality of SQ is warm, musical and euphonic. The midrange displays some secondary octave nuances, which is very unique and can hardly be found even among the top-end German tubes. Similar to the Telefunken tubes, the SQ's can create infinite levels of harmonic depth and a liquid sonic texture without altering the musicality of the sound. The bass on these is the clear winner of the Heerlen tubes family: articulate, accurate, deep, textured, full-bodied and powerful. The sound stage is wide and structured - it feels the dimensions of the sound shape are clearly defined no matter how it moves.  

Vocal representation on the SQ's is close to Mitcham and Blackburn Mullard tubes in terms of warmth, sweetness and texture, making them great alternatives to Mullard's as the best vocals tube. But what truly shines on SQ tubes, especially the ones from the 1960s like this pair, is their magic in portraying piano music: creamy smooth, richly colored, realistic and intimate. For many audiophiles (incl. ourselves), they're the go-to tube for piano sound. Listening to Claudio Arrau's Beethoven Complete Piano Sonatas on these tubes should be on your bucket list if you happen to be into classical piano music, but even if you are not, these tubes' superb "interpretation" of piano music from any genre will amaze you.

The ultra low noise on SQ's also sets them apart from most of the high-end tubes. They don't just compete with Telefunken tubes in low noise; they're known for being a long-term leader in low noise. As a result, you get superb detail and clarity from these tubes as well. 

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 Tube Testing 

This set was tested and certified by RoeTest V11 tester with the following result: 

Tube 1:

Measured transconductance(GM): 10.66/10.34 mA/V  - 85%/83% (100% = 12.50 mA/V)
Measured plate current(IA): 11.001/10.941 mA  - 73%/73% (100% = 15 mA)

Tube 2:

Measured transconductance(GM): 10.02/10.05 mA/V  - 80%/80% (100% = 12.50 mA/V)
Measured plate current(IA): 14.541/12.899 mA  - 97%/86% (100% = 15 mA)

NO shorts, leakage or gas. NO noise or microphonics.

Curve trace is also included in the original RoeTest report.

Appearance & cosmetic condition

Besides the world-class sound characteristics, we still treasure this pair for its near pristine cosmetic condition given the tubes' age - nearly 100% of the paint is still intact on both tubes, and the very close (practically identical) acid-etched date codes of the Heerlen factory are perfectly visible on both tubes: 

7LH ⊿4B2 (7L = E88CC, ⊿ = Heerlen, 4 = 1964, B = February, 2 = Week 2 of the production month)

Shipping Policy 

 - US Shipping: Flat-rate USPS Ground Advantage (upgradable to flat-rate USPS Priority or FedEx 2nd Day for expedited delivery.)

 - International Shipping: (Please read carefully) USPS First Class International is used for all countries EXCEPT: Armenia, Chile, China, India, Latvia, Mauritius, Mexico, Serbia, Slovenia, Tuvalu, and Vietnam. If you prefer to use a different carrier or shipping service, please contact us first so we can establish shipping rates before you make payment. If you are a buyer in one of the excluded countries, you must contact us prior to purchase to arrange shipping. Soundlumia-sponsored 3-day guaranteed worldwide delivery program ($30 flat rate for ALL destinations in the world) via DHL Express is highly recommended to serious and committed buyers. 

 - Same day shipping: Orders placed by 2:00PM US Pacific Time on weekdays are posted on the same day, otherwise the next business day. 

 - Combined shipping available - request invoice for total before making payment or receive shipping credit after order ships. 

Return Policy - Please READ carefully

Returns are acceptable if we made a mistake by delivering you wrong or defective products. Tubes we sell are guaranteed to work because we run professional tests and sound evaluation TWICE: before they are approved for listing AND before we ship them to customers. So the "defective item" case doesn't exist and please do not bother trying - this type of returns will NOT be accepted without proof that tubes are faulty and we will open disputes with eBay. Sound experience is very subjective and we do NOT accept returns because you do not like the tube's sound signature or because you changed your mind about your purchase. Please contact us to work things out before submitting return requests claiming "item is defective" or "item not as described" or "just didn't like it" or "changed my mind."

Tube rollers abusing the return system will be reported to eBay immediately and negative feedback will be left to your account - that's guaranteed. We have already opened several dispute cases to report abusive buyers and eBay has always ruled in our favor. International buyers who request return or refund claiming your country's import duties or sales tax/GST/VAT are too high will be reported to eBay immediately for dishonesty and will be permanently blacklisted from purchasing from Soundlumia. We are committed to working closely with eBay to help rid the marketplace of dishonest, unjust, unreasonable, abusive buyers that are detrimental to the vintage tubes market and the audiophile community.