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ARC D 70 II

71.63.69.67
Posted on August 8, 2024 at 09:35:28
dgaapc7
Audiophile

Posts: 431
Joined: August 16, 2013
 I am getting my second D70, regretting selling one a few years ago.
Question- there are 4 power tubes, either 6550s or KT 88s. There is a fifth power tube that I think is part of the power supply. Can one use an 88 for power supply and 6550 s for power, or vice versa?
Supposed to arrive today. A terrific amp. Will compare to my MC 275 vi and restored MAC 1500, amp section only. Hey, a classic shoot out in me own home.
LowIQ

 

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RE: ARC D 70 II - Yes, posted on August 8, 2024 at 10:00:58
Chip647
Audiophile

Posts: 2693
Location: The South
Joined: December 24, 2012

The "5th" tube is just a pass element for the regulator section.
It just has to be a properly functioning tube of the 6550/KT88 family.
It does not have to match the others.

 

RE: ARC D 70 II - Yes, posted on August 8, 2024 at 13:38:24
dgaapc7
Audiophile

Posts: 431
Joined: August 16, 2013
 Thanks for the info. I'm listening to it right now, delivered two hours ago. Just biased with 6550's. The 6550s are labeled made in USA, but I can't seem to find a brand label.
Why did I ever sell the first one I had? The amp is terrific, with the trademark ARC way of making the music sound lively, full, and colorful.
LowIQ

 

RE: ARC D 70 II - Yes, posted on August 14, 2024 at 02:12:52
Akolegov88
Audiophile

Posts: 399
Joined: January 7, 2014
 If the 6550 tubes are straight-bottle shape, they are most probably GE.

 

FWIW dept.: that amp is old enough that the power supply is at risk. , posted on August 14, 2024 at 09:50:54
Ralph
Manufacturer

Posts: 4839
Location: Minnesota
Joined: April 24, 2002
 Make sure the filter caps in the power supply have been replaced. You might have already done that, but if not, they have a way of burning up the main power transformer which is something you really want to avoid!

 

I have an early Dual 50, posted on August 14, 2024 at 17:52:33
www.records
Audiophile

Posts: 4996
Location: SW Missouri
Joined: December 22, 2003
 that is marked Electronic Industries and need a complete rebuild. I got it in a storage clean out of vintage audio stuff almost 20 years ago.

 

RE: I have an early Dual 50, posted on August 14, 2024 at 20:52:41
hahax@verizon.net
Audiophile

Posts: 4432
Location: New Jersey
Joined: March 22, 2006
 That is old. It was in a period Bill Johnson had sold ARC before buying it back.

It brings back memories. I owned a Dual D MK2 that was modified to a DUAL 50 F MK2. Unfortunately it blew up 3 times in 3 years. That was a difficult version, so Bad Audio Research them selves took my amp in trade for a Dual 51. That was a much better experience.

 

Dates back to '69, posted on August 15, 2024 at 08:00:17
E-Stat
Audiophile

Posts: 38852
Joined: May 12, 2000
Contributor
  Since: April 5, 2002
 according to ARCDB.

Schematics and pics found at link.

 

RE: Dates back to '69, posted on August 15, 2024 at 09:25:34
Sondek
Audiophile

Posts: 9930
Location: Fort Worth
Joined: May 17, 2000
Contributor
  Since: April 5, 2002
 And I thought my Acoustat amps were ugly. That's a close runner-up to them, IMO.

 

RE: Dates back to '69, posted on August 16, 2024 at 07:39:48
www.records
Audiophile

Posts: 4996
Location: SW Missouri
Joined: December 22, 2003
 I have seen that site. I have no plans for doing anything with it. It make an excellent door stop. :)
It's in pretty rough shape, especially after digging it out of the tornado rubble.

 

RE: Dates back to '69, posted on August 16, 2024 at 07:44:32
www.records
Audiophile

Posts: 4996
Location: SW Missouri
Joined: December 22, 2003
 Yeah, she is like a 400 lb woman with 2 kids. You would have to think they were twins, because who could imagine someone sleeping with her twice.

 

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