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| Model: | SX-1000TW - Allied 395 |
| Category: | Receiver |
| Suggested Retail Price: | $265 used |
| Description: | Stereo Receiver |
| Manufacturer URL: | Pioneer |
| Review by sony6060 on April 21, 2021 at 19:46:27 IP Address: 47.26.52.145 | Add Your Review for the SX-1000TW - Allied 395 |
The Pioneer SX-1000TW (Allied 395) is a very good sounding receiver. It is an all discrete design avoiding the less than great early Op-Amps that many receivers used in the mid 1970s thru 1980s. The receiver is capacitor coupled on the speaker output that some say is more tube like in sonics. What this receiver needs is the ELNA Silmic II 1000uF 50 volt speaker output audio grade capacitors and replace the two 1000uF @ 100 volt power supply capacitors with 2200uF @ 100 volts DC. I would buy the highest ripple current rated power supply capacitors you can find.
I compared the re-built Allied to a Marantz 2270 and find the Allied 395 superior sounding. I also compared to an upgraded tube amp with best tubes and the Allied was surprisingly close in performance. It is extremely clear and distortion is low enough to not be detected. The soundstage is wide that produces sound beyond the speaker edges. The speakers at least in part mostly disappear. A wide soundstage and speakers disappearing are the two most important parameters in great sound.
The receiver produces 50 watts per channel and has a damping factor of 25. Similar to a tube amp of 30-50 watts damping factor.
The receiver is often overlooked as it is not well known. It is Pioneer's first high-end receiver. This receiver is a great value as used costs $200 to $250.
If you find the SX-1000TW or Allied 395 in good condition I would not hesitate purchasing. You will be hard pressed to find a better sounding vintage receiver after the Silmic II audio grade capacitors are installed.
| Product Weakness: | none |
| Product Strengths: | Excellent sound |
| Amplifier: | Allied 395 |
| Preamplifier (or None if Integrated): | none |
| Sources (CDP/Turntable): | Luxman PD-272 with VM540ML |
| Speakers: | Revel M22 |
| Cables/Interconnects: | zip cord/Blue Jeans |
| Music Used (Genre/Selections): | Rock & Roll |
| Room Size (LxWxH): | 17 x 15 x 10 |
| Room Comments/Treatments: | none |
| Time Period/Length of Audition: | 7 days/30 minutes |
| Other (Power Conditioner etc.): | none |
| Type of Audition/Review: | Product Owner |
| Your System (if other than home audition): | none |
-when I worked at the Allied RS Service dept.
The voltage regulator probably has been replaced. If not they can develop thermal intermittents.
The FM IF section employs 6-legged ICs that were a common failure issue. A number of generic replacements have existed over the years and work fine. The complaint is weak reception- not much inter-station hiss. The failing IC can be diagnosed by jumping a small disk cap (0.01uf is good) from input to output. If the FM reception improves you found the bad part.
I would not just replace the output coupling caps and power supply caps although that is a good place to start. Really any of the electrolytic caps in the signal path are suspect.
Its a good idea to put the unit on the bench and run a low distortion sine wave through it and just listen to the waveform at a low volume level. Quite often the bias was set a little low and crossover distortion can be heard. You can increase the bias a bit to just get rid of this. But some units will run hot depending on the device used in the circuit- there are variants! There is an electrolytic coupling cap at the input of the power amp board- replace it. Do not use tantalums!
The amp section employs thermisters for thermal feedback. This system works alright but is not as accurate as diode thermal feedback. Be careful if servicing the output section as the thermisters are fragile!
I would replace every electrolytic capacitor on the regulator board.
The output of the unit uses those goofy Pioneer connectors which look a bit like the prongs of an AC power cord but one prong is rotated 90 degrees with respect to the others. You can find these on ebay, search on Pioneer speaker plugs and a variety of them will show up.
The design of this circuit tends to make a bit of 2nd ordered harmonic which causes it to sound pretty smooth until you turn it up. But if you put it beside a good tube amp you'll probably not want to keep playing the Pioneer. In a nutshell at the time the semiconductors that were really needed to make a low distortion solid state amp really didn't exist. The THD of this unit is 1%...
Thanks. I will replace all the capacitors on preamp and driver boards.
If you are replacing the output caps to the speakers, they are 1,000uF. If you like tight bass change them to 2,200uf. Don't go higher unless you are going to up the main, twice the old value is pretty much a limit. If you go higher you might have nuisance fuse trips. If you double that it should be safe to go to three times on the outputs, to 3,300. Should.
This will give you noticeably better low end.
-----[EVIL LIVES]-----
Now to show it off, at your discretion of course, get a couple of 0.0039uF caps and put them across the bass controls. Off the top of my head I think it lowers the turnover frequency by about 2/3rds octave, or at least 1/2.
Now you can use the bass control without making the sound all muddy. And don't think it is like "not purist", it wasn't the minute after it came out. And you are just compensating for deficiencies. That low bass is being restored.
Can you explain .0039uF across the bass controls? Do they replace an existing capacitor, or simply solder across the bass potentiometers? If so, what two pot leads are you referring to?
It does not replace, it augments. It is effectively added to the capacitance it already has. You remove nothing.
I should have noted the phono amp section is close to flawless and as good as my tube phono amplifier. Never heard that from any solid-state phono amp.
For some reason this Allied 395 (Pioneer SX-1000) just does not have the slight haze of the newer 1970s-80s silver face Pioneers with possible exception of the SX-1010 and higher power Pioneers.
Highly recommended, but you must replace the power supply with new 2200uF caps and the speaker output 1000uF capacitors with ELNA Silmic II 1000uF @ 50 volts DC to get the best sound as described.
Newer silver face Pioneers (compared to the SX-1000 series) use a poor sounding op-amp in the phono amp. You have to buy SX-850 and higher power models to avoid that bad news op-amp. Any new amp with phono-stage will outperform the op-amp Pioneers.
Edits: 05/02/21
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