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basses on SX-950 Vs SX-750
- Thread starter Aja097
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If 50 wpc beat 85 wpc, I would say yes.
Retro
Retro
Unican_Eric
Pioneerious Collecticus
What sources were you using for the side by side comparison?
Was it FM, turntable CD etc:
Were you running 2 sets of speakers? Were both receivers running at the same time with say the FM being a source?
Its possible that the speakers could give you a different result as they are not the same. Could be the source as well. Different CD players may have a different output level giving you a different level. Lots to concider here.
Lets also say if it was the FM you were using for the comparison. Maybe its just the FM that has a problem in one of the receivers that is not doing its job properly.
There is just to much to concider to jump to the conclusion that your driver board might need recapping.
Course I could be wrong.
Was it FM, turntable CD etc:
Were you running 2 sets of speakers? Were both receivers running at the same time with say the FM being a source?
Its possible that the speakers could give you a different result as they are not the same. Could be the source as well. Different CD players may have a different output level giving you a different level. Lots to concider here.
Lets also say if it was the FM you were using for the comparison. Maybe its just the FM that has a problem in one of the receivers that is not doing its job properly.
There is just to much to concider to jump to the conclusion that your driver board might need recapping.
Course I could be wrong.
agger said:
I agree. As the value of an electrolytic coupling cap goes down, due to aging (drying of the electrolyte), the bottom end will roll off.
If you are going to open her up to the degree needed to replace the coupling cap(s), you might as well do the full monte, and replace all the electrolytic caps (except maybe the main supply caps, unless they are swollen or leaking). Retouch the pcb solder joints as well (even more important).
Rich P
Unican_Eric
Pioneerious Collecticus
Now remember I did say I could be wrong.......I usually am. But I try.... 
Aja097 said:
Finding the electrolytic coupling caps, if any, is a fairly technical operation. Essentially, your amp is made up of several amplifier stages, performing various functions (tone control, straight amplification, mixing, etc.). Often, the manufacturers used electrolytic capacitors to couple the audio signal from the output of one amplifier stage to the input of the next stage. Since these are usually low value capacitors, they are usually quite small. Aluminum electrolytic capacitors depend on a moist electrolyte, between their plates, in order to function and provide the required value and voltage rating. Over a long period of time, the electrolyte can dry to various degrees. The small ones are more subject to the drying out, than the large main supply caps, simply because they have a smaller internal volume. Unless you are fairly well versed in electronics fundamentals, you will need the assistance of a technician, with the needed schematic, to tell you which caps are used for coupling.
Note: Most of the original capacitor series used in these old units are long obsolete. Selecting replacements, from current manufacturers and their series, is also a task requiring a qualified tech. There are many parameters to consider (operating temp, value, value tolerance, life expectancy, effective series resistance, internal losses, size, etc.).
As to why the solder joints need to be refreshed...The life expectancy for a wave soldered connection (used in circuit board manufacturing) is around 30 years. They tend to oxidize, and fracture, etc. I have had more units fail for aged solder joints than for aged capacitors, by an easy order of magnitude. When I recap a unit, I always retouch all of the circuit board solder joints.
Note: Styrol (polystyrene) capacitors are extremely sensistive to heat. They cannot tolerate temperatures above 85 degC, and will be damaged is subjected to higher temps. Soldering involves temperatures in excess of 200 degC. You must clip a heatsink clip between the capacitor and the solder joint when retouching joints associated with styrol caps.
Rich P
Last edited:
Aja097
Member
pustelniakr said:
Thanks for explanation. I had a look at the service manual and even if all boards are really distinct and easy to maintain it's quite a big task for me to change these caps. I think i'm going to try to locate if problem may come from pre-amp or amp side as there is a jumper on the SX950 between them. Then ...
Jerome
Aja097
Member
Then ...
i changed all coupling caps :
pre-amp; tone control; power amp with nice Elna ROD caps :yes:
Changed some other caps as well such as power supply with Panasonic FC ...
And now this 950 is just gorgeous :thmbsp:
mmmhhh just listening to old R. Wyatt stuff .... oh My ...
Jerome
i changed all coupling caps :
pre-amp; tone control; power amp with nice Elna ROD caps :yes:
Changed some other caps as well such as power supply with Panasonic FC ...
And now this 950 is just gorgeous :thmbsp:
mmmhhh just listening to old R. Wyatt stuff .... oh My ...
Jerome
reggaenaut
Addicted Member
Davidb the bass on the 7070 is one of the most articulate I have heard on a receiver.
I have found that the 750/650's volume control to be different than the 850/960/1050 by advancing the volume farther with less turn on the knob making them appear more powerful. They are putting out more at the same point on the knob up to their maximum output. . .
Someone might explain the difference better. . . In the ones I have owned they were wide open at 11 O-Clock where the 850/950 were not at max until 1 or 2 O-clock if this makes any sense. . .
Even the 650 running "flat" seems to deliver more bass at lower levels almost like the loudness was engaged earlier. . . .
I can not say if this is right or not just my experience from the 4 or 5 650/750s that I have owned and the several 100(total) bigger models (780/850/880/950/980/1050). . .
If the 650/750s weren't so damn heavy for their output. Other 35-50 watt receivers weigh about half of what they weigh making shipping too expensive. . .
Someone might explain the difference better. . . In the ones I have owned they were wide open at 11 O-Clock where the 850/950 were not at max until 1 or 2 O-clock if this makes any sense. . .
Even the 650 running "flat" seems to deliver more bass at lower levels almost like the loudness was engaged earlier. . . .
I can not say if this is right or not just my experience from the 4 or 5 650/750s that I have owned and the several 100(total) bigger models (780/850/880/950/980/1050). . .
If the 650/750s weren't so damn heavy for their output. Other 35-50 watt receivers weigh about half of what they weigh making shipping too expensive. . .