Sony STR-6060F Restoration and Upgrade

thanks for the welcome!

I am very curious how you will rate your 6060 once upgraded. as I see in your signature you also own a 6120. is that restored, too? would be curious about the differences. and how compares the 6055 re bass and treble sweetness?

.....

eschenborn

Congratulations on making progress on your 6060. It may be a few months before I get mine back from restoration but I am very curious to hear what it sounds like.

My 6120 is all original but sounds very good to my ears. I haven't decided whether to have anything done to it. My 6055 is also original but I've never had any complaints about the sound of the bass (thru Bose 301's or my BIC 66's).

Except for the 6060, none of my other Sony receivers have been worked on and I'm at the point of deciding whether to sell some off to fund restoration of a few keepers.
 
I have two 6055s, one I recapped last summer, and one 6065. None are bass shy or flabby. The recapped 6055 seems to me to have flatter bass response than the original one, which seems to have a bit of a mid-bass hump. Perhaps yours also had this hump. Extension is just fine on the recapped model, but it was different than the unrestored version.
 
with all restorations Leestereo-style I could hear amazing differences between the status quo before and after. normally, however, these changes were audible immediately. I am astonished that it took so much time. I don't think that I simply adjusted my hearing.

now, with the bass present, I would say that there is much more of it then before I started soldering. I did not really hear the midbass hump. the 6060 already sounded remarkably open for a device unchanged for 50 years, more so than many others from that time. but the bass was weak. this is why I expected it to be there after the upgrade.

@jwhvt : I am curious what you will experience once you get the unit back. does your tech do a like-for-like recap or will he go for an upgrade?
 
not so sure anymore about the tonal balance of the 6060.

after listening to some more vinyl I put the 6050 back into the chain and – it IS more bassy. it just makes some not so good recordings (like old motowns) sound less bad – but not because it seriously loses detail, but because it is warmer. the 6060 sounds a bit solid state, too much for me to bear it for a long time listening without starting to try to change things (this is why I post here again). very tight lows, yes, but it sounds like too much NFB.

so I pulled out R632 and C633 in the preamp, just to test without NFB. it sounded much fuller – but also extremely hissy.

I am curious if I could swap the preamp transistors into low noise ones and experiment with leaving out NFB altogether. but there might remain still some hiss. it could use some more gain as well, as I need to crank up the volume nearly to 12 o clock to get good listening volume. on the other hand I am sorry for all these surgical thoughts, as it is a great legacy amp.

@Moving Ahead : if I understood you well, you exchanged the transistors in your KA-1120 preamp, and it had a much fuller sound afterwards. did I get it right? but you left the circuit as it is I assume.
 
So you're ready to go to the dark side?
Let me reinstate I have not had the pleasure of seeing a 6060 in the flesh so what I pass on you can take with a grain of salt.

Firstly as you can appreciate it is a historical piece and one must appreciate this- warts and all.
And secondly I don't know about your str unit but I'd rather have a lobotomy than work on the 1120 again. So proceed at your own peril.

The 1120 should be your big brother- so I can assume it shares the same DNA. Yes I did change out the sC631,sC632. They were all 430hFE +-5%. I replaced with low noise type with higher gain than the originals. I than tied a knot in the head amp feedback. I replaced with old resistor to match the original look so no one will know any different. So yes I kept the circuit the same. I doesn't achieve a zero noise floor but man I can hear a pin drop.
In addition Q1 on the main amp board-c631 I changed out too. I applied a little pressure to the brake pedal here cause of the earlier changes.
Now the heat sink has dropped about eight degrees as the volume is about 10 o'clock. Which works for me as the thermal compensation diodes can now have a holiday.

The unit I have brings much joy.
 
I love the comments about the circuit integrity and parts quality having a big effect on the overall sound of an amplifier..I was flamed pretty good by someone in another thread who insists that there is no difference whatsoever in the headroom,over all feel etc. between amps..He also challenged me to call Mcintosh engineers who he supposedly talk to 3 times to confirm that 50 watts is 50 watts etc. Hope their boss doesn't read those quotes, because it might interfere with future pricing :)..
Totally agree with your soft top end comments. I think that's the key to fatigue free listening. Soft top end to me doesn't mean lack of detail, but a refined sweet level of detail..cheers!
QUOTE="Leestereo, post: 8353091, member: 1051"]The Restoration Casualties:



Power Amplifier Adjustments

The STR-6060F is an output capacitor-coupled design and as such there is an AC balance adjustment in addition to the idle current(bias) adjustment. Note that the AC balance adjustment should be done first as it will affect the idle current adjustment. Interestingly, measurements taken before the restoration showed that the AC balance on the left channel was off by ~7V, no doubt due to the failing output coupling capacitor. With the new output coupling capacitors installed, only a minor adjustment to the AC balance of each channel was necessary. The owner had also noted that the left channel heatsink was noticeably warmer than the right one; indeed, the initial left channel idle bias measured 38mV (>3X the prescribed 12mV). With the bias was adjusted to the proper setting, the Sony just gets slightly warm, even after playing for a couple of hours.





Sound Impressions of Restoration/Upgrade

Before starting the restoration/upgrade, I listened to the STR-6060F for several hours in one of my systems (substituting for a restored NAD 106 preamp and harman/kardon hk770 power amplifier). During these initial listening sessions, some notes were kept (since I didn't want to rely on just my sonic memory) for comparison with the restored/upgraded unit.

As received, the STR-6060F was quite pleasant to listen to, it had a non-fatiguing presentation and the vocals, in particular, were clear and natural sounding. My impression (from memory), is that this Sony sounded more clear, uncoloured than most of the unrestored vintage receivers that have crossed my workbench of late. This may largely be due to Sony's use of (wherever possible) film capacitors and silver mica in the signal path of the preamplifier and power amplifier stages rather than the more common practice of using electrolytic or ceramic capacitors. The bass, while full sounding, didn't seem to be very extended nor "tight" sounding (in retrospect, this is not that surprising considering the under-sized main power supply capacitor and output coupling capacitors as well as the chosen F3 cut-off of the high-pass filters). Similarly, the treble range did not seem particularly extended and could be characterized as sounding "soft", with recessed sibilants. For example, recordings that are known to have an aggressive high range (e.g. Standage/ECO Four Seasons; Rolling Stones/Some Girls; Led Zeppelin/Mothership) sounded uncharacteristically subdued; the likely culprit here is a frequency dependent rise in ESR in the old electrolytic coupling capacitors.

Following the restoration/upgrade, I listened to the Sony for a couple hours before the owner picked it up. Playing selected tracks from recordings that I'm very familiar with (e.g., Steely Dan/Aja; Miles Davis/Kind of Blue; Beatles/Abbey Road; Dave Brubeck/Time Out), the sonic difference from the stock condition was quite noticeable. The most obvious change was in the sound of the bass range (<240Hz); it had a more "authoritative" presence; and was subjectively deeper and "tighter". As mentioned above, the treble range was somewhat "soft", but was now subjectively more extended and natural/real sounding (e.g., the different percussion timbres are easily discerned). Overall, the sonic presentation was now more lively/dynamic.

A couple of other thoughts: IMO, the sound of this Sony, or any other unit, is the result of the circuit topology and the implementation of this topology, i.e., the quality of the components used in the build maximize/enhance the sound potential of the design. As this project hopefully demonstrates, the sound of a good (vintage) design can be even better than its original incarnation by replacing the failing/tired components with upgraded parts that either didn't exist (e.g., stacked film capacitors) or weren't available in a size small enough to fit the design (e.g., high capacity, high voltage capacitors) or were deemed too costly by the bean counters when the unit was originally manufactured.[/QUOTE]
 
So you're ready to go to the dark side?
Let me reinstate I have not had the pleasure of seeing a 6060 in the flesh so what I pass on you can take with a grain of salt.

Firstly as you can appreciate it is a historical piece and one must appreciate this- warts and all.
And secondly I don't know about your str unit but I'd rather have a lobotomy than work on the 1120 again. So proceed at your own peril.

The 1120 should be your big brother- so I can assume it shares the same DNA. Yes I did change out the sC631,sC632. They were all 430hFE +-5%. I replaced with low noise type with higher gain than the originals. I than tied a knot in the head amp feedback. I replaced with old resistor to match the original look so no one will know any different. So yes I kept the circuit the same. I doesn't achieve a zero noise floor but man I can hear a pin drop.
In addition Q1 on the main amp board-c631 I changed out too. I applied a little pressure to the brake pedal here cause of the earlier changes.
Now the heat sink has dropped about eight degrees as the volume is about 10 o'clock. Which works for me as the thermal compensation diodes can now have a holiday.

The unit I have brings much joy.

thanks. that's very interesting. which transistors (numbers) did you use then?

I am always flirting with the dark side. although I am hesitating to do this change, because it is not my only amp, and it is fully functional. the legacy thing. and I have used up all my spare time for the moment. but it would be interesting to hear what difference there is.

I was wondering about how it sounds without NFB altogether. not sure if this is possible in that circuit, as any transistors, even low noise, may introduce some hiss. but what I heard in the low end when I shortly eliminated the pre-amp global NFB circuit was a very full low end.

can aging transistors cause a different sound balance? or was the amp designed like that?

@FOH Engineer : the strange thing is that my 6060 unit is on the border of too bright. super revealing and extremely resolving with some recordings, to bright and sharp with others. this is what I meant with "to solid state". my experience is that normally the older the vintage SS gear is, the less pronounced is the SS flair of it, and the nicer it is to listen to. so for me the 6055 was a step down from the 6050. in that logic, and due to many happy owners posting their bliss, I was thinking that the 6060 was even better. but there might be wide variations between single units of the same model.
 
thanks. that's very interesting. which transistors (numbers) did you use then?

I am always flirting with the dark side. although I am hesitating to do this change, because it is not my only amp, and it is fully functional. the legacy thing. and I have used up all my spare time for the moment. but it would be interesting to hear what difference there is.

I was wondering about how it sounds without NFB altogether. not sure if this is possible in that circuit, as any transistors, even low noise, may introduce some hiss. but what I heard in the low end when I shortly eliminated the pre-amp global NFB circuit was a very full low end.

can aging transistors cause a different sound balance? or was the amp designed like that?

@FOH Engineer : the strange thing is that my 6060 unit is on the border of too bright. super revealing and extremely resolving with some recordings, to bright and sharp with others. this is what I meant with "to solid state". my experience is that normally the older the vintage SS gear is, the less pronounced is the SS flair of it, and the nicer it is to listen to. so for me the 6055 was a step down from the 6050. in that logic, and due to many happy owners posting their bliss, I was thinking that the 6060 was even better. but there might be wide variations between single units of the same model.
I think that the degradation of caps resistors etc. leads to a path of eventual sonic critical mass...just before failure or going out of spec it seems like the fatigued parts pass a little more of a relaxed sagged signal as opposed to a fast critically clean signal...and frankly it's very pleasent if your listening closely...I think you experienced that on initial listening..I think cap replacement should be approached pretty cautiously..You might feel the same way as I do because it seems like there is recap fever going on with new "used" purchases..When maybe just a minor tweaking is all that's needed...I'm not referring to qualified experts doing a valid renovation like yourself. But people instantly recapping everything , kind of because everybody else says they did....sort of like audio peer pressure....Your thoughts are eagerly awaited, as you obviously get it.
 
I think that the degradation of caps resistors etc. leads to a path of eventual sonic critical mass...just before failure or going out of spec it seems like the fatigued parts pass a little more of a relaxed sagged signal as opposed to a fast critically clean signal...and frankly it's very pleasent if your listening closely...I think you experienced that on initial listening..I think cap replacement should be approached pretty cautiously..You might feel the same way as I do because it seems like there is recap fever going on with new "used" purchases..When maybe just a minor tweaking is all that's needed...I'm not referring to qualified experts doing a valid renovation like yourself. But people instantly recapping everything , kind of because everybody else says they did....sort of like audio peer pressure....Your thoughts are eagerly awaited, as you obviously get it.

thanks @FOH Engineer for replying. I agree that first gen SS units mostly have a very nice sound "as is". recapped they mostly open up quite a bit, particularly if treated in Leestereo manner, which means taking into account the function of the cap and uprating it gently if necessary. after such a recap, the best of them can be pretty clean but not fatiguing, just sweet and airy and open with no grain. when I compared my sony STR-6060 to my 6050 I compared two totally recapped items. on listening "as is", the 6060 was already quite crisp, but a bit edgy, and lean on bass. the edginess went away, but the leanness remained.

re my 6060, I just wonder why the effect on the bass is so slim. I am pondering deeper changes, just for curiosity.
 
looks like you've got an itch you can't scratch.
To me it only makes sense considering all the killer amps you have.
You'll get there.
 
Hi everyone,

I just picked up a Sony STR-6060F from a friend and ran into some problems with it trying to test it out. Hooked up a couple of speakers and there was no sound coming out of the left channel. Tried to use the headphone jack and it sounded horrible (bass was booming with loudness set either ON or OFF with lots of static in the background). Opened it up to check the capacitors and looks like there were a few leaks. I am a newbie at this and have no electrical background so I was unable to identify a few of the leaky capacitors. Most of the leaked capacitors are on the top side board right behind the Tuning dial and two on the board right beneath that board on the bottom side. The ones I could not identify are:

4700J 50 ST.A
224K 50 NCC
STYCON 4700J WV50V

I did a quick search on the net and was able to find out that 4700J mean 4700pF with 5% tolerance and WV 50V is working voltage of 50V. I could not find anything on what the 224K 50NCC mean. Could anyone tell me what the suitable modern replacements are for those three capacitor? Your help is greatly appreciated.

As I've mentioned earlier, since I'm a newbie with no electronics background, would it be worth doing this myself or have a shop do the repair for me? I am decent with the soldering iron (have done some desoldering and soldering for an old Walkman repair) but have not tried to replace capacitors. I want to learn but am afraid that I would do permanent damage to the receiver.

PS. All of the pictures on the restoration posted by Leestereo are no longer visible. Could someone repost them? Thank you.
 
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OK, looked through the service manual and the parts list online and I figured out that Stycon and 4700J 50 ST.A are both 4700pF, 50V, 5% tolerance capacitors on the MPX decoder board. I can not find any suitable replacement on the online websites. Can anyone suggest one?

Also, the 224K 50 NCC turned out to be two of the same resistors on the preamp board. The parts list stated that they are 560 ohm 5% tolerance RDI/4SR. Not sure what RDI/4SR means. Can I use any resistor that fits the spec or is there a specific type better suited for this application? Also, I thought resisters don't leak but there are some hardened brown stuff at the feet of both resisters. Maybe it's just accumulated dirt? Didn't see that on any other resistors on the same board though. The resistors are the two green ones in the attached photo with the brown stuff spilling over to the neighboring resistors. Any suggestions at this point would be highly appreciated. Thanks.
 
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Lee,
Great stuff you have done here. Would happen to have a list of all the parts you used so I can order all at once.

I just picked up one yesterday. At first I used the 4 ohm Infinity RSb’s to test it for a few minutes it sounded good but when I saw smoke coming out of the power supply lid line wtf, I opened it up to see if there was some burnt smell. Then I used a pair of 8 ohm speakers and it never had issues. So I’m assuming these units don’t like 4 ohm speakers ?
 
Does the UF4006 diode need to be rated 3A/600V? Can’t seem to locate that size at Mouser or Digikey.
 
Thanks. Can you provide a part number for the safety caps? Also, what are your thoughts on installing a CL60 thermistor to mitigate turn on thump?
 
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I just wonder if someone in the know could at least roughly describe to a layman how capacitance of coupling caps is calculated in an upgrade like this for a desired cut off frequency.
 
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