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Sony STR-6055 hum and low volume problem

Hammett

Hammett

Active Member
Hi all,

I recently picked up an STR-6055 to go along with my STR-V4.

They are very different units, with the STR-V4 being much fuller sounding, with a tonal balance that decidedly leans toward the lower frequencies. It is a joy to listen to as the treble is actually quite detailed, while not being in any way harsh.

The STR-6055 leans toward the brighter end of the spectrum, with tight bass, but also a slightly edgy treble. It is also very enjoyable to listen to.

The problem is that the STR-6055 requires the volume to be much higher than any other receiver/amp I own. It is normal to run it at 11:00 or 12:00 or even 1:00, for music or television. I am not hard of hearing nor a teenager. To put this in perspective, it is rare for me to go beyond 9:00 or 10:00 on any other amp.

I have thoroughly De-oxited the receiver. The DC offset is 2.6mv/8.2mv. The amp runs cool.

There is a hum, apparently from the transformer, when I first turn it on--maybe about a second and a half long. It rises and then quickly falls. Other than the volume and turn on hum, the amp seems to run normally.

I bought the amp with the intention of ultimately recapping it, but the volume issue makes me wonder if it is not something else, such as transistors.

Does anyone have any thoughts on what it might be?
 
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greetings and welcome to AK.

It's not a over powering amp at 40watts per and hungry speakers at 8ohm will have an effect. I doubt its transistors as you claim quality of sounds. As for the initial 'hum', that 'may' (maybe) be cured with capping the power supply mains, perhaps an arrestor cap on the power switch per inrush current. Haven't look at the Serv. manual. http://www.hifiengine.com/manual_library/sony.shtml
 
Binkman said:
greetings and welcome to AK.

It's not a over powering amp at 40watts per and hungry speakers at 8ohm will have an effect. I doubt its transistors as you claim quality of sounds. As for the initial 'hum', that 'may' (maybe) be cured with capping the power supply mains, perhaps an arrestor cap on the power switch per inrush current. Haven't look at the Serv. manual. http://www.hifiengine.com/manual_library/sony.shtml
Click to expand...

Hi Binkman,

Thanks for your response. The sound is quite nice. A little bright, but still vert listenable. I have other 40 watt amps and lower and do not need to turn them up this high. The volume does not start to become noticeable until I hit at least 9:00 (from a starting point at 7:00)

I have been looking over the service manual like nobody's business. Are you referring to C809-C813 (p. 42 for the diagram and p. 53 for parts list)? These are on my list to recap.
 
I've had a 6055 since new and they have a very slow taper pot for volume. Don't panic, that's just how they are. The intention was to make small changes at low levels more easy. I've always liked it that way. It may put you off but it's actually working just fine. They made use of the whole range available.
 
sinewaver said:
I've had a 6055 since new and they have a very slow taper pot for volume. Don't panic, that's just how they are. The intention was to make small changes at low levels more easy. I've always liked it that way. It may put you off but it's actually working just fine. They made use of the whole range available.
Click to expand...

Thanks Sinewaver! That is very interesting.

What a great site! That is not the sort of information you can find just anywhere. The volume taper is definitely slow, but other than that it does seem normal (no big jumps etc.).

I am still left wondering about that turn on hum.

Any ideas anyone?
 
Hammett said:
Hi all,

The problem is that the STR-6055 requires the volume to be much higher than any other receiver/amp I own. It is normal to run it at 11:00 or 12:00 or even 1:00, for music or television. I am not hard of hearing nor a teenager. To put this in perspective, it is rare for me to go beyond 9:00 or 10:00 on any other amp.

I have thoroughly De-oxited the receiver. The DC offset is 2.6mv/8.2mv. The amp runs cool.

There is a hum, apparently from the transformer, when I first turn it on--maybe about a second and a half long. It rises and then quickly falls. Other than the volume and turn on hum, the amp seems to run normally.
Click to expand...

Both my STR6055 and my STR6065 make a brief rushing sound when I first power them on. Maybe that's the "hum" you refer to. I think it's due to their design ("cap coupled" ?)? Typical listenining volumes for all of my STR60xx are at 10 o'clock on a variety of speakers (Klipsch Forte's, Bose 301's, BA40's). What speakers are you using and how efficient are they?

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I just leave my STR-6055 turned on 24/7 and dispense with the startup/shutdown noises and warm-up noises. Probably needs to be re-capped but it sounds perfect right now so that's how I leave it. Normal listening volume into Kef 104/2s is at 10 o'clock.
 
bluemooze said:
I just leave my STR-6055 turned on 24/7 and dispense with the startup/shutdown noises and warm-up noises. Probably needs to be re-capped but it sounds perfect right now so that's how I leave it. Normal listening volume into Kef 104/2s is at 10 o'clock.
Click to expand...

It is starting to sound more and more like these characteristics are normal for this model.

I have been running it with Acoustic Energy Evo 1 (90 db claimed, 84 db measured), Pioneer FS52 (87 db) and Pioneer BS22 (85db), all of which are lower than Klipsch Fortes or KEF 104/2s.

The unit does not seem to be running out of steam, it just has to be turned up a bit.

I have to say that I am enjoying it immensely.

In twenty years it is also the only piece of audio equipment my wife has commented on positively!
 
The relative position of the volume control is a function of the gain of the amp stages and the input level of the source device or internal tuner - not to mention the efficiency of the speakers being used.

Frankly, I never understood why manufacturers of audio gear set the gain levels so one never got close to 12 o'clock on the volume control. For one, it limits the use of the control and, for another, it reduced the value of the Loudness feature, which tapers off across the rotation of the control.

Just my thoughts on the matter.

Cheers,

David
 
Greeting Hammett!

The sounds you are hearing when you turn it off and on are what I would describe as "normal". There is no relay to prevent sound from coming through when the receiver first powers up. You may also hear a light thump through your speakers when you turn it off. If either are bothersome you can always turn the speakers off before turning the power off and waiting a few seconds when powering the unit on before engaging the speakers. The volume control is also performing normally based on what you have described.
 
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