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Sound Rating: 5 / 10 # Owners: 1
Relaibility Rating: 5 / 10 Views: 155

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Technical Details

Brand: Pentron






Country of Manufacture:USA

Release dates:1954 - 1957

Original Price: $190

Tracks:1/2 Rec/PB

Speeds: 3 3/4, 7 1/2

Max Reel Size("): 7"

Number of heads: 2

Head Composition: Permalloy

Head Configuration: Mono - Full Track

Voltage(s): 110-120v

Outputs: RCA

Frequency Response:50 to 9.5 kHz (all 3 dB) 7½ ips

Wow and Flutter:less than 0.5%

Signal-to-Noise Ratio:50 dB

Sound quality rating:5 / 10

Long-term reliability rating: 5/ 10

Additional Details


Quite similar to the earlier 9T series, the TR-4 was a portable, dual-speed, dual track machine with push-button select for either 7½ or 3¾ ips. It was also available with full width, single track heads. Signal to noise ratio was 50dB and wow & flutter measured less than 0.5% at 7½ ips.
There was an edit key and magic eye level indicator and the in-built 5 watt amplifier drove a 6″ permanent magnet speaker.

The two input jacks (left hand side) were for radio, TV or phono and microphone.  The outputs were for an external speaker and external amplifier or headphones.  The Model HT-225 Hi-Fidelity was more or less identical to the TR-4 except that it had an extended frequency range due largely to the installation of two “woofer” speakers and a tweeter together with an LC crossover. Prices in 1954 were $190 for the TR-4 and $225 for the HT-225.

Additional Info

Valve complement: 5879 or 6J7 (mic pre-amp). 6SL7 (AF amp). 6V6GT (bias & audio) 6E5 (record level indicator) and 6X5GT (rectifier) / Rewind speed: 7″ 1200 ft reel in 70 seconds (20:1 ratio) / Audio output power: 5 watts / Inputs: radio / TV / phono and microphone / Outputs: external speaker and external amplifier or headphones / Speaker(s): 6″ permanent magnet (TR-4) two 6″ woofers and a tweeter with LC crossover (HT-225) / Weight: TR-4: 27 lbs (12.3 kg) HT-225: 33 lbs (15 kg) / half-track mono (full-track available)


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