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Accuphase e470

Mikechw

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Hello Accu480 and Mikechw,

I believe you need/should directly contact with headquarter of Accuphase Laboratory, Inc. in Japan using their inquiry page;
http://www.accuphase.com/contact/contact_us.html
to communicate and discuss the issue(s) you have with E-480 etc., and, as far as you can, you need to share the communication with Accuphase at here in this thread.

Otherwise, I assume, this thread would be misleading, or giving unfair, inproper message and/or impressions to the people visiting here...

Please note that I am just one of the end users of Accuphase product (E-460), and I have no conflict of interest at all with Accuphase Laboraroty, Inc.
I think the unit can reach quite high temperature. I couldn't keep my hands on the top of the unit when its hot.
(There is around 8 cm on top of it to let out the heat.)
I had it inside my wooden cupboard and the ventilation isn't as ideal..

I solved this by installing this AC Infinitiy fan on top of it and I am happy with it. I can listen to it as long as I like.. Also its winter time at the moment.
The air on top of it should be below 40°C all the time.
1.jpg


I could send an query to Accuphase Japan and see what is their reply.
 

dualazmak

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In my project with ACCUPHASE E-460, YAMAHA A-S3000 and SONY TA-A1ES, I carefully arrange (layout) them in "open air";
WS001338.JPG


WS001340.JPG


For details, please visit my thread, especially post #307 and thereafter in page 16, and finally the post #311 containing the above two photos. I placed these four posts just one hour before today.
 
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Balle Clorin

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Regarding sound qualiity and temperature , the E480 and other newer units do not use the Toshibas Accuphase used to use but had to change to Fairchild MOSfets since Toshiba stopped production, some units even use bipolar transistors. The characteristic of the Fairchild is quite different from the classic Toshibas. I do think my A48 with new transistors sound better than my A36 with the classic MOSfets , regardless of temperature. But the Toshibas look very linear in the Data sheet
 
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kschmit2

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Since I am using E-460 with great satisfaction, I would highly appreciate if we could hear measurements of E-470, E-480, E-380, E-650 and also E-800; these are the recent integrated amp series from ACCUPHASE!

Accuphase measurements:
https://www.stereo.de/hifi-test/produkt/accuphase-e-800-1911
https://www.stereo.de/hifi-test/produkt/accuphase-c-2150-1765
https://www.stereo.de/hifi-test/produkt/accuphase-p-4500-1766
https://www.stereo.de/hifi-test/produkt/accuphase-e-480-1641
https://www.stereo.de/hifi-test/produkt/accuphase-t-1200-1601
https://www.stereo.de/hifi-test/produkt/accuphase-dp-560-1552
https://www.stereo.de/hifi-test/produkt/accuphase-c-2450-1480
https://www.stereo.de/hifi-test/produkt/accuphase-a-47-1481
https://www.stereo.de/hifi-test/produkt/accuphase-dp-430-1307
https://www.stereo.de/hifi-test/produkt/accuphase-e-270-1106
https://www.stereo.de/hifi-test/produkt/accuphase-e-370-972
https://www.stereo.de/hifi-test/produkt/accuphase-dc-37-886
https://www.stereo.de/hifi-test/produkt/accuphase-c-2120-771
https://www.stereo.de/hifi-test/produkt/accuphase-p-4200-772
https://www.stereo.de/hifi-test/produkt/accuphase-dp-550-590
https://www.stereo.de/hifi-test/produkt/accuphase-e-260-548
https://www.stereo.de/hifi-test/produkt/accuphase-c-2820-386
https://www.stereo.de/hifi-test/produkt/accuphase-a-46-387
https://www.stereo.de/hifi-test/produkt/accuphase-dp-510-262
https://www.stereo.de/hifi-test/produkt/accuphase-e-460-263
https://www.stereo.de/hifi-test/produkt/accuphase-p-6100-184

right-click on the measurement graphs and open image in new tab
 
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kschmit2

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I’ve emailed Accuphase and awaiting feedback. After reading the comments of the E270 review, I’m curious why someone hasn’t asked Accuphase for their measurements on the e270 to compare with Amir’s.

They're included in the Japanese manual for the E-270:
1626353492471.png
 

St1n

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Again, I have lots of use of my E-480 using many different input and output configurations, and I have never encountered this issues you are describing.
I recently pulled the trigger on an E-480 and the recently released DAC-60 upgrade card. I really hope I don't experience any of that...

Trying to downsize my setup, and use the E-480 during the summer months, and also use it as a pre-amp with some Class A power amps during the cooler months, or when I'm in that kind of mood.
 

trl

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I had E480 for over a year. The amp sounds very clear when its cold/warm.. After it heats up, I noticed sound quality does degrade.. My friend told me its because mosfet's noises increase with temperature.. I have a little temperature controlled fan on top of E480. And now my E480 sound good for as long as I have it turned on..

Try to keep your E480 in open space may help.
I don't think the way the output transistors are mounted on the heatsink is the best, see the below pics:

dz0xMjAwJmg9MTEwNQ==_src_39257-accuphase_e470_fot3.jpg

Power transistors are moounted on the edges of the heatsink


dz02NzgmaD00NTI=_src_61172-accuphase-e-470-fot6.jpg

Few mm away from the edge of the heatsink
I would move the transistors couple of inches away from the sides/edges of the heatsink and also rotate them with 90 degrees for a better heat dissipation, due to the fact that the thermal resistance of the heatsink itself is higher than zero (zero being the ideal heat conductivity of a heatsink). Also, the three transistors from each channel are one on top of the other, so heat dissipated by the lower transistor would move up to the transistor on top. On ideal conditions, with proper convection and maybe active cooling too, this may not be an issue.

@restorer-john and @solderdude maybe would like to jump in a bit here, meanwhile I consider that repositioning the output transistors would lower their inside junction temperature with few degrees.
 

A Surfer

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I don't see any possible way to move them, there just isn't any room and I cannot imagine a tiny move even if possible changing things in any substantive way. What am I missing here?
 

trl

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My message was mostly related to how the manufacturer positioned the transistors, probably not in the best way to minimise heatsink temperature. I don't think you should try moving those transistors!
 

St1n

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It's possible that he was having issues with his E-480 due to bias -- maybe the trim pot was bumped out of position during shipping?

I'm seeing around 23mVDC on the these test points (TP1; on top of the unit, next to the transformer and filter capacitors). I'd be curious to know what other E-480 owners see their bias set to.
PXL_20210831_195723564.jpg
 

Balle Clorin

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The 23mv is not necessarily the bias. It is just the voltage over a parallel part . In A36 the similar test point is 40mV or somrthing, but that corresponds to an actual bias current of more than 1A,,
 
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pierre

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If I am reading the graphs correctly, the new e480 has 5x the distortion of the e470 at 1W (converging to the same at full output). Correct?
 

restorer-john

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If I am reading the graphs correctly, the new e480 has 5x the distortion of the e470 at 1W (converging to the same at full output). Correct?

The E-480 has a lot more high frequency distortion. They have switched their output stage MOSFETs as the Toshibas they were using are EOL. I think that will be the main issue causing the THD.
 

Dichotome

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The E-480 has a lot more high frequency distortion. They have switched their output stage MOSFETs as the Toshibas they were using are EOL. I think that will be the main issue causing the THD.
Does anyone know just when they switched to Fairchild mosfets? In particular do the A-75 and A-250 have the Toshibas?
 

Moises

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I think the unit can reach quite high temperature. I couldn't keep my hands on the top of the unit when its hot.
(There is around 8 cm on top of it to let out the heat.)
I had it inside my wooden cupboard and the ventilation isn't as ideal..

I solved this by installing this AC Infinitiy fan on top of it and I am happy with it. I can listen to it as long as I like.. Also its winter time at the moment.
The air on top of it should be below 40°C all the time.
View attachment 105779

I could send an query to Accuphase Japan and see what is their reply.
952FAD7A-77DF-471A-B66B-12A2EBDB5316.jpeg
 
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