Join me again as we look at another (semi-)baby amplifier, the gorgeous Sony TA-1150 integrated amp.

Welcome back, everybody, for another in my baby amplifiers series. A lot has been happening at Liquid Audio in the past few weeks, and I’m inundated with work as usual. That said, things could be a lot worse, so here’s another article on what I hope to make a regular/semi-regular Monday morning spot. I hope you enjoy it!

Quick question: Would anyone be interested in a M-E-G-A amplifiers series, a counterpoint to these baby amplifiers? Let me know in the comments because I have plenty of those to write about!

Baby Amplifiers, Power & SPL

I wrote a primer about baby amplifiers in my first baby amplifier article about the Kenwood KA-4002A, so you can check that for a quick refresher. In a nutshell, though, the baby amplifiers I’m interested in are discrete hi-fi stereo amplifiers with around 20 Watts per channel, or less, and hailing from when such things were well-made and repairable. 

That means no integrated, midi, music or shelf systems. It also excludes cheap modern plastic stuff, which you don’t want to read about anyway. Classic baby hi-fi amplifiers I’ve written about before include the stunning Naim Nait, Mission Cyrus One, and Marantz 1030 from last week, and the Sansui AU-101, which I will feature soon.

The Sony TA-1150 outputs 30 Watts per channel, and so is not a true baby like the others we’ve looked at. In terms of the listening experience, though, 20 Watts vs 30 Watts represents under 2dB difference and is therefore essentially inaudible. You need to double amplifier power to yield a 3dB increase in sound pressure level (SPL), considered a perceptible increase. For more on the relationship between power and SPL, read this.

The TA-1150 fits the brief in every other way, so she’s in. I may include other 30-Watt models, I’ll see how I go in terms of time, energy, etc. There are, of course, baby receivers, such as the stunning Sansui 661 AM/FM stereo receiver I’ve just listed for sale in my store. PS – there’s also a beautiful matching Sansui SR-212 turntable in the store, for anyone wanting a complete vintage Sansui system..!

Sony TA-1150 Design & Features

I’ve previously written about the Sony TA-1150D, a later variant of the TA-1150, so check that out if you haven’t already. Sony always did things a little bit differently, as you will see when we look inside the TA-1150. In terms of build quality, though there isn’t much in it, the Sony TA-1150 is probably the best built of the three baby amplifiers that we’ve looked at so far. There’s a jewel-like quality to Sony amplifiers; they truly are wonderful to work on.

Most of these baby amplifiers use small output devices because of their low power output. The previous models we looked at used little TO-66 output devices. The Sony TA-1150 uses even smaller TO-220 devices, but more of them. TO-220 devices are typically used as driver transistors rather than output devices. To reach the rated power, the Sony amplifier utilises four devices per channel. You can see them at the top of the amplifier, below.

The 2SA670/2SC1060 devices used here are each rated at 25 Watts max power dissipation. That is pushing these tiny devices, so Sony has conservatively used 4 devices per channel, meaning each device dissipates a maximum of 7.5 Watts. That’s well within their design limits, hence the reliability of this design. These devices can easily be replaced with various modern, rugged alternatives, so no dramas here in terms of longevity.

The Sony TA-1150 does contain operational amplifiers or op-amps, unlike the previous baby amplifiers we looked at. These are located in the tone and phono preamp circuits. Op-amps – two of them here – are used to simplify the design and reduce the parts count, and therefore the cost.

In terms of features, this lovely TA-1150 is once again all metal, very heavy for its size and power rating, and built to last. The proof is the 100% original parts inside this 50-year-old amplifier. Let that sink in for a moment. That’s right, this amplifier is completely original, at 50+ years of age. It contains not one single replacement part. You’d be lucky to get 5 years from a cheap modern amplifier.

The Sony TA-1150 features separate left and right channel bass tone controls, high and low frequency filters, loads of inputs, including two turntables and tape inputs. Many folks had two turntables in the ’70s. There are even tone control turnover frequency switches for those looking for that last bit of functionality from their tone controls. This is certainly the most fully featured of the baby amplifiers we’ve looked at so far.

Sony TA-1150 Specifications

As always, courtesy of our friends at HiFi Engine

Power output: 30 watts per channel into 8Ω (stereo)

Frequency response: 15Hz to 80kHz

Total harmonic distortion: 0.1%

Damping factor: 100

Input sensitivity: 2mV (MM), 140mV (line)

Signal to noise ratio: 70dB (MM), 90dB (line)

Output: 140mV (line), 24mV (DIN), 0.8V (Pre out)

Speaker load impedance: 4Ω to 16Ω

Semiconductors: 26 x transistors, 3 x diodes, 2 x IC

Dimensions: 400 x 149 x 316mm

Weight: 8.3kg

Year: 1973

Service

This Sony TA-1150 came to me courtesy of a new customer, but someone who’d utilised my advisory service and enjoyed my articles over the years. Tony, the owner, told me that he read my TA-1150D article some years ago and decided he just had to have one. I don’t blame him!

This particular unit needed the usual age-related cleaning, service and adjustment. All the controls were noisy and needed attention, particularly the slider potentiometers. The tone controls needed to be re-indexed as they no longer pointed where they should be. Quiescent current adjustments were also considerably out of spec. Thankfully, Sony engineers designed equipment like this to be serviceable.

Results

I’m not sure I even really need to say anything here. The noisy switches and controls are gone, DC symmetry and quiescent current are spot on, and this baby Sony TA-1150 sings sweetly as she was designed to.

Folks looking for a vintage baby amplifier would be well served tracking down a Sony TA-1150 or TA-1150D. These are heirloom pieces in many ways because of their incredible reliability, timeless good looks, and sonic performance.

Remember, we’d put people on the moon when this was made. Do you reckon we could do it now? We had the technology to make superb audio gear decades ago. Nothing in this is TA-1150 superseded by something dramatically better, but things are made more cheaply now.

Yes, modern transistors have lower noise and handle more power, but the Sony TA-1150 isn’t that kind of piece. I made the phono preamplifier in the Marantz 1030 much quieter by replacing old devices, for example, so this is no big deal in what are not edge-case high-end pieces.

Amplifiers like the Sony TA-1150 are not high-end pieces in sonic terms, but they represent a high-water mark in terms of design and construction of affordable equipment, from a bygone era. The TA-1150 sounds wonderful, is affordable, reliable, and you can pass it on to your next of kin. What’s not to love about that?!

Thanks!

As always, thank you for visiting. I hope you enjoyed this article and maybe learned something. If you’d like me to take care of your Sony TA-1150 or other vintage Sony amplifier, don’t hesitate to let me know.

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