A Technical Comparison

Among a majority of users of vintage Tandberg receivers it seem to be an agreement that the Huldra 10 (H10) are to be considered "the best" sounding. Or possible more accurate explained, — the warmest sounding of Tandberg's amplifiers with unique timbres and nerve. Much of its sound character stems from its discrete build and the single supply push-pull transistor power amplifier with a big capacitor in series with the speaker output.

Still Huldra 10 second hand prices do not confirm this expressed admiration compared to some other models often mentioned when users ask for buying recommendation of Tandberg amps or receivers.

Trying to better understand as to why this is, and to clear some misconception found online we had a deep dive into schematics and forum posts.

Below we've broken down each model to show some of the differences with focus on amplification function only. With one exception none of the often recommended models should sound "as" a Huldra 10. We asume they all sound good of course, but why would the marked upscale prices on some of those other models rather than the Huldra 10 itself that everyone compares to?

• Availability could be one major factor. Huldra 10 considered a top model where in production for numerous years. Longer than TR-1000/1010 which got replaced by TR-1040/1055 only two years after introduction. Leaving a lot more or less working H10 still around compared to the more powerful alternatives. Similar can be seen for TA-300 and TR-200 which also values less than they're good reputation would expect.
• Form factor also seems important. With cabinet width at 53.5 cm H10 are more than 10 cm wider than the 43 cm standard the industry later settled on. When your vintage stereo has to be hidden inside a cabinett, or fit on standard rack shelf this feature might tip the scale in favor of one of the more narrow models.
• And of course there are users also looking at power rating for more easily finding speakers to fit. Guess the appeal of modern RCA connectors and screw speaker terminals aren't completely worthless either.

"Closest I came to tube sound without the hassle of tubes"

"Tandberg did well with the transition from tubes to transistors"

anonymous forum members

Huldra 10 2x25W/8Ω

• Single supply push-pull power amp
• 61VDC single power rail
• Seperate transformer windings and rectifier to supply 25VDC to radio/preamp
• Up until serial number 471500 Huldra 10 had TBA231 op-amp in the phono/riaa stage — then changed it in favour of a descrete transistor circuit.
• Output transistors: MJE3055/MJE2955
• Output capasitors: 4700µF changed to 3300µF on later units
• 2 pin and 5 pin DIN connectors only
• Later models had many 22µF caps values upped to 47µF throughout all printed circuit boards with no changes made to the schematics.
• From s/n 483170 accuracy for the FM stereo decoder are better using IC on the main board. But if sound quality for the FM receiver are of importance we are supposed to look for serial numbers from 477000 to 484000 still using transformers. Else later models (as in newer) are noted to sound better for amplification duties.
• W53.5 H12 D30.5 cm, 8.2 kg

TA-300(M) 2x25W/8Ω

• Single supply push-pull power amp
• 59VDC single power rail
• Power amp share secondary transformer windings and rectifier bridge with the preamp
• Early models with serial numbers from 1220000 to 1220500 made use of the TBA231 op-amp in the phono/riaa amp just as early H10.
• Output transistors: MJE3055/MJE2955
• Output capasitors: 4700µF/40VDC in place - 4000µF shown on schematics
• With the exception of a simpler power supply the schematics are nearly a blueprint from Huldra 10 without the radio tuners. Even the tuner input makes use of the extra transistor stage (2.7x gain) shared by the phono input after the riaa, — just as it is done in the H10. PCB and chassis layout are somewhat different from H10 and for specimen we've had on the work bench film caps are different brand/type than H10.
• As H10 the TA-300 has 2 and 5 pin DIN connectors only, even the microphone input
• Unique features:
  • Two Phono inputs sharing a single riaa/phono amp.
  • Tape Monitor function on both tape inputs for use with tape machines with separate recording/playback heads.
  • Two headphone jacks
  • Stereo Mono-L Mono-R, — all in L/R swap places
  • The TA-300M model has microphone input with a fader to mix with any selected source before the power amp. Can not be routed to tape out.
• W43 H8.7 D24.3 cm, 5kg

TR-1000/1010/1020 2x35W/8Ω

• Single supply push-pull power amp
• 64VDC power rail
• Seperate secondary transformer windings and rectifier to supply 25VDC to radio/preamp
• Seperate secondary transformer windings, rectifier and 3300µF cap for each power amp channel oddly enough, H10 has better channel seperation (crosstalk) given Tandbergs numbers are ment to be read as negative numbers like -60dB/1kHz vs TR-1000's -52dB
• TBA231 op-amp used in the phono/riaa stage using indetical circuit as seen in early Huldra 10. Not changed until sometime into TR-1040
• Output transistors: MJ802/MJ4502
• Output capasitors: 3300µF
• RCA and 5 pin DIN connectors
• Speaker terminals with screw posts and 2 pin DIN
• RCA have different impedance with higher output voltage (changing two resistor values give H10 similar line output voltage)
• Unique features:
  • Seperate Left/Right bass & tremble control
  • Can be used as preamp with Tape 3 Preamp Record activated
  • TR-1000 FM only
  • TR-1010 FM/AM
  • TR-1020 FM/AM different AM board to TR-1010 possible US only including ferrite aerial?
• W43 H12 D30.5 cm, 8.8 kg

TR-1040/1055 replaces TR-1000/1010/1020

• Dual supply push-pull power amp
• TR-1040 2x40W/8Ω, +/-40V dual power rails
  TR-1055 2x55W/8Ω, +/-45V dual power rails with seperate secondary transformer windings, rectifier and 4700µF cap for each power amp channel
• Seperate secondary transformer windings and rectifier to supply 25VDC to radio/preamp.
• Models with serial numbers up until 1426000 made use of the TBA231 op-amp in the riaa/phono. Then switch to discrete transistor circuit with close resemblance to Huldra 10 throughout
• Output transistors: MJ802/MJ4502
• Output capasitors: None, — not needed with differential power supply alternating at 0 volt. No longer having a cap to block DC offset errors at startup and power down a relay on the speaker output are introduced on this model.
• For TR-1055 there are a simplification to power amp circuit from serial number 1426401 bringing it closer to TR-1040 now only differentiated by the PSU
• Model name ending with P have preset buttons for FM radio stations
  Model name ending with A have AM radio and FM (launched late 1974)
• RCA and 5 pin DIN connectors
• Speaker terminals with screw posts and 2 pin DIN
• RCA Preamp Out and Power-Amp Inputs on US version
• Level trimpots for line inputs on the back (loading source signal to ground)
• W44.5 H13.5 D31 cm, 9 kg

TR-200 2x15W/8Ω

• Single supply push-pull power amp
• ??VDC power rail
• Power amp share secondary transformer windings and rectifier bridge with the preamp and radio
• TBA231 op-amp used in the phono/riaa stage using indetical circuit seen in early Huldra 10
• Output transistors: 2N5496/2N5496
• Output capasitors: 2500µF shown on schematics
• Simpler circuit throughout with no Hi/Low filters
• W43 H8.7 D24.3 cm, 5 kg

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