Pioneer SX-750 vs SX-838, sound very different, need restoration?

[lshj2015]

I bought a Pioneer SX-750 as it was highly recommended here with typical sound of the 50 series receiver. Recently I bought another Pioneer SX-838 mainly because of good price. None of these two receivers have been restored or serviced, I believe both have the original electrical components.

Both have similar power with 50w per channel. I compared these two with different speakers, I have noticed that the 838 sounds significantly better than 750 to my ear no matter which speaker I have tried. The major difference is that 750 has much enhanced bass and sound too muddy at lower frequency compared to 838. I tried to decrease the bass on 750 but no matter how I adjust it with tone control, the 838 always sounds better.

I know these are old receivers. Without restoration to replace the aged component it won't be a fair comparison. I probably will restore one of them that I like the most. I like the looks of SX-750 but like the sound of SX-838 much better. The Sx-750 is smaller which is another big advantage to me. I would like to hear any advice with people who have experience with similar pioneer receivers. I am not sure if the enhanced bass of SX-750 is a typical sound character of Pioneer 50 receiver, or it is mainly due to aged capacitors that restoration will make it much better? If Pioneer 50s receivers all have typical enhanced bass compared to x3x receiver, I probably won't waste my time to restore the SX-750. I really like the look of SX-750 and wish I could make it sound better with restoration.

 

[lshj2015]

When I bought SX-750, the guy also has a SX-850 on sale which cost twice as much as 750. But SX-850 is significantly larger with more knobs. I personally like the appearance of 750 better and I am not a big fan of larger size and too many control knobs. They all said that SX-750 and SX-850 sound similar. So it's a easy choice for me to pick SX-750. I don't need another Pioneer receiver but just saw a SX-838 with very good price at Craigslist. I bought SX-838 half the price of SX-750 but surprised to found that it sounds much better to me.

 

[Watthour]

It is not only capacitors which can change over time, but carbon resistors as well. There are plenty of both in the audio path, including the tone control circuits.

Consider yourself fortunate that this is not a later 1970's Kenwood receiver, with the "printed on" carbon resistors. That makes it a greater challenge to repair.

 

[lshj2015]

It is not only capacitors which can change over time, but carbon resistors as well. There are plenty of both in the audio path, including the tone control circuits.

Consider yourself fortunate that this is not a later 1970's Kenwood receiver, with the "printed on" carbon resistors. That makes it a greater challenge to repair.

That's interesting to know. I have a Kenwood Kr-4400, really love the look of this Kenwood receiver, but not much of the sound. I have read many post about restoration, but rarely seen people replacing resistors, maybe because too much work or resistor only make subtle change?

I don't have very sensitive ear, never expect that I could hear difference between different amplifiers. I have a Elekit 8200 tube amplifier, I compared it to Marantz 2275, Yamaha AS-301 modern amplifier, a Sansui 7900z receiver, I couldn't hear any significant difference among all these. So I thought maybe most amplifiers are similar, or the difference is too subtle for my ear. Then I bought Kenwood kr-4400, and Pioneer SX 750. These two receivers sound significantly different with different sound character compared to other receivers that I have owned. If my ear can hear significant difference, then the difference might be huge like day and night to some other people.

 

[Watthour]

Speaking of Kennys, I have a pair of KR-6050s which sound remarkably different when compared on the same speakers. One was fairly clean, but had some output problems. The other was a complete DOA unit which appeared to have been submerged, as in hurricane Katrina submerged. Both are working, but the filthy/rusty/wet one has a very muffled, dull, lifeless sound compared to its brother - Very bass-heavy as you describe the SX-750. I suspect the printed resistors were under as much water as the rest of the unit, and thus may have been altered significantly in value. It's in one of the racks, waiting for my time.

 

[lshj2015]

Speaking of Kennys, I have a pair of KR-6050s which sound remarkably different when compared on the same speakers. One was fairly clean, but had some output problems. The other was a complete DOA unit which appeared to have been submerged, as in hurricane Katrina submerged. Both are working, but the filthy/rusty/wet one has a very muffled, dull, lifeless sound compared to its brother - Very bass-heavy as you describe the SX-750. I suspect the printed resistors were under as much water as the rest of the unit, and thus may have been altered significantly in value. It's in one of the racks, waiting for my time.

That's a really rusted machine. My Kr-4400 was well kept by the original owner, in almost like new condition. The inside only has some dust, but not rust or corrosion that I can see. The Pioneer sx 750 was also in very good condition although not as good as Kenwood Kr 4400, but still very good condition considering these are more than 40 years old. That's why I thought they might just sound like that or due to aging. The Kenwood kr 4400 sound very muddy to my ear although I really like the look of this receiver. I might try to restore it if it's not too much work. I heard it's a receiver easy to work with, not very complicated.

 

[spicer]

I bought a Pioneer SX-750 as it was highly recommended here with typical sound of the 50 series receiver. Recently I bought another Pioneer SX-838 mainly because of good price. None of these two receivers have been restored or serviced, I believe both have the original electrical components.

Both have similar power with 50w per channel. I compared these two with different speakers, I have noticed that the 838 sounds significantly better than 750 to my ear no matter which speaker I have tried. The major difference is that 750 has much enhanced bass and sound too muddy at lower frequency compared to 838. I tried to decrease the bass on 750 but no matter how I adjust it with tone control, the 838 always sounds better.

I know these are old receivers. Without restoration to replace the aged component it won't be a fair comparison. I probably will restore one of them that I like the most. I like the looks of SX-750 but like the sound of SX-838 much better. The Sx-750 is smaller which is another big advantage to me. I would like to hear any advice with people who have experience with similar pioneer receivers. I am not sure if the enhanced bass of SX-750 is a typical sound character of Pioneer 50 receiver, or it is mainly due to aged capacitors that restoration will make it much better? If Pioneer 50s receivers all have typical enhanced bass compared to x3x receiver, I probably won't waste my time to restore the SX-750. I really like the look of SX-750 and wish I could make it sound better with restoration.

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My two cents... I remember when that later line of the SX Pioneer receivers first came out and I thought they did not sound 'as good' as the previous line with the black out look. It was as though the signature sound of Pioneer receivers had changed. With that said the new line was very popular. All things being equal, which they aren't, I'd keep the 838 because I prefer the look.

 

[lshj2015]

My two cents... I remember when that later line of the SX Pioneer receivers first came out and I thought they did not sound 'as good' as the previous line with the black out look. It was as though the signature sound of Pioneer receivers had changed. With that said the new line was very popular. All things being equal, which they aren't, I'd keep the 838 because I prefer the look.

I read some posts here and learned that the x50 receivers are very popular today for pioneer vintage receivers, people praised a lot for the sound of x50 receivers. That's why I always want buy a SX750 which has the highest power for that size. Receivers higher than 750 are significantly bigger.

I never planned to buy a 838 initially, just found a one with a very good price. Surprised to found that I like its sound so much better. I actually like the look of 750, but not the sound.

 

[spicer]

I read some posts here and learned that the x50 receivers are very popular today for pioneer vintage receivers, people praised a lot for the sound of x50 receivers. That's why I always want buy a SX750 which has the highest power for that size. Receivers higher than 750 are significantly bigger.

I never planned to buy a 838 initially, just found a one with a very good price. Surprised to found that I like its sound so much better. I actually like the look of 750, but not the sound.

I hear you... actually, if I found locally a cosmetically sound SX 828 for a good price I'd buy it, rebuild and use it. I like the blackout look and in my opinion they have good sound... plus I've had a number of them on the bench back in the day and know what they need. I wonder if you'd been happy with the sound of the 750 without having the 838 to compare... that's the 'problem' with this hobby...

 

[Blue Shadow]

The earlier units x2x were replacing the tube units and voiced to be a nice unit. The x3x kinda continued this but the x50 series was more about better specs and that clean sound is harsher sounding to many. Lots of love for both the 3 and 50s but up to the listener as to which they prefer. The smoother more musical sound of the early units of the cleaner sound of the later units.

 

[lshj2015]

I hear you... actually, if I found locally a cosmetically sound SX 828 for a good price I'd buy it, rebuild and use it. I like the blackout look and in my opinion they have good sound... plus I've had a number of them on the bench back in the day and know what they need. I wonder if you'd been happy with the sound of the 750 without having the 838 to compare... that's the 'problem' with this hobby...

I actually wanted to buy a 828 because I really like the look. But have no luck to find a one with reasonable price. I don't like the sound of 750 even without hearing the 838. To my ear, the 838 sound more balanced, not like 750 with boosted bass and bright high frequency. I do like the the sound of my Marantz 2275.

 

[lshj2015]

The earlier units x2x were replacing the tube units and voiced to be a nice unit. The x3x kinda continued this but the x50 series was more about better specs and that clean sound is harsher sounding to many. Lots of love for both the 3 and 50s but up to the listener as to which they prefer. The smoother more musical sound of the early units of the cleaner sound of the later units.

Sometime I am really confused with what is really tube sound. I have an Elekit 8200 tube amplifier, to my ear, My Maramtz 2275 and Pioneer 838 are more close to the tube amplifier I have. The Marantz 2275 has more modern sound I believe, clean, dynamic, and more details, that is also what I feel for my Elekit 8200 tube amplifier, definitely not "warm" sound that people refered to. But Elekit 8200 is a modern tube amplifier, not vintage tube amplifier. Maybe my SX 750 is a bad one, just has too much bass that is not well balanced sound.

 

[spicer]

I actually wanted to buy a 828 because I really like the look. But have no luck to find a one with reasonable price. I don't like the sound of 750 even without hearing the 838. To my ear, the 838 sound more balanced, not like 750 with boosted bass and bright high frequency. I do like the the sound of my Marantz 2275.

The 828 and Marantz 2275, that series of Marantz have similar sound to my ears. I hesitate to say... but I didn't like the sound of that generation of Pioneer receivers from the first time I heard them... the ones from the series of the 750. They had excellent tuners though and good specifications across the board.

 

[exybeth3]

if i may comment in this 838 vs 750, the 750 does have a ic in the tone board for the opa, a ta7136, but the 838 is a more traditional transistor board based opa "operational amp" we did rebuild the 750 to a nice extent, excluding resistors, and found that with a modified opa board and a texas instruments opa604 in the place of the ta7136, the clarity was inhanced, but yes, 750, bassy unit

 

[rulnacco]

if i may comment in this 838 vs 750, the 750 does have a ic in the tone board for the opa, a ta7136, but the 838 is a more traditional transistor board based opa "operational amp" we did rebuild the 750 to a nice extent, excluding resistors, and found that with a modified opa board and a texas instruments opa604 in the place of the ta7136, the clarity was inhanced, but yes, 750, bassy unit

Hi! I find your comment interesting. I just refurbed my SX-750 myself. It sounds good, but if it can be made to sound even better (particularly in terms of clarity), I'd be all for that. It doesn't look like the OPA604 is a direct drop-in replacement for the TA7136, but if I were to get an OPA604, could I use this adapter to insert the OPA604 into the circuit? How did you modify your OPA board? Thanks for any information you can provide!