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Explain parafeed OPTs in an DHT SET amp

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Posted on February 11, 2015 at 23:04:45
Frihed89
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Posts: 15703
Location: Copenhagen
Joined: March 21, 2005
 How do they differ from the use of air gapped OPTs in the output stage of an SET. For that matter how does the output stage differ?

What are the comparative strengths and limitations of parafeed OPTs vs air gapped OPTs.

 

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Link, posted on February 12, 2015 at 08:35:46
Caucasian Blackplate
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Posts: 8313
Location: Seattle
Joined: June 18, 2004
 Here's some basic reading on the subject. Do note that the *dis*advantage of parallel feed is that it costs *more*.

 

RE: Explain parafeed OPTs in an DHT SET amp, posted on February 12, 2015 at 10:37:41
LinuxGuru
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Posts: 582
Location: European Union
Joined: November 11, 2008
 Hi, Frihed89,

Parafeed output transformer is much cheaper and easier to build having the same inductance and much lower parasitic parameters. It don't need air gapped core and can fully utilize magnetic properties of core material.

I think parafeed SET with solid-state CSS is something worth building.

Sonic signature will be quite different from traditional SET, and many die hard SET fans may say parafeed SET is not a real SET.

 

Have you ever bought a pair of AN(UK) Doual C-Core OPTs? nt, posted on February 12, 2015 at 10:49:04
Frihed89
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Posts: 15703
Location: Copenhagen
Joined: March 21, 2005
 nt

 

And thanks nt, posted on February 12, 2015 at 10:53:29
Frihed89
Audiophile

Posts: 15703
Location: Copenhagen
Joined: March 21, 2005
 nt

 

RE: Have you ever bought a pair of AN(UK) Doual C-Core OPTs? nt, posted on February 12, 2015 at 11:22:36
Caucasian Blackplate
Industry Professional

Posts: 8313
Location: Seattle
Joined: June 18, 2004
 I haven't used them, but if you'd like to send me a pair, I'd be happy to try them.

 

RE: Have you ever bought a pair of AN(UK) Doual C-Core OPTs? nt, posted on February 12, 2015 at 18:12:54
alexz
Audiophile

Posts: 52
Joined: June 24, 2010
 I was listening to 300S transformers for a few months.
What is the question ?

 

Simply a reply about price to CB, posted on February 12, 2015 at 22:53:01
Frihed89
Audiophile

Posts: 15703
Location: Copenhagen
Joined: March 21, 2005
 about the relative cost of parafeed OPTs compared to "high end" OPTs used in cap-coupled output systems.

 

RE: Simply a reply about price to CB, posted on February 13, 2015 at 09:51:09
Caucasian Blackplate
Industry Professional

Posts: 8313
Location: Seattle
Joined: June 18, 2004
 Unfortunately, the Japanese way of doing things in audio often means that key measurements are missing. In the case of the Audio Note single ended transformers, there doesn't seem to be any indication of primary inductance.

There is also a note that they match output transformers by frequency response for their amps, but they don't actually say what that nominal frequency response is for any of their transformers.

I think for price comparison, it makes more sense to price iron from companies that make both parallel feed and series feed iron, like Sowter or Magnequest. If Audio Note did a parallel feed output transformer and ate choke set, it would undoubtedly cost more than a single series feed transformer.

 

RE: Simply a reply about price to CB, posted on February 13, 2015 at 10:13:53
Frihed89
Audiophile

Posts: 15703
Location: Copenhagen
Joined: March 21, 2005
 I was referring to Audio Note (UK). Never owned any Kondo gear.

 

Pros and Cons ..., posted on February 13, 2015 at 14:04:59
Naz
Audiophile

Posts: 2184
Location: Sydney
Joined: September 2, 2005
 from someone who has built both.

OP tranny for Parafeed is smaller, lighter and cheaper ... think PP trannies. No air gap means inductance can easily be made higher for good bass. Overall BW is usually easy to make superior to air gapped trannies as used in SETs. One other advantage is that it's possible to tune the OP stage (cap and tranny) for gentle bass boost to compensate for speaker roll-off PROVIDEd you have sufficient headroom. So far all good!

The big downside is having to use a sizable choke and what some miss is the fact that it MUST be high quality or sonics will suffer (same as if you used a poor quality OP tranny in a SET). Since the choke must be air gapped it takes you right back where you started. In addition you must use a cap and it too must be high quality.

Frankly, IMO there is little sonic difference between well designed SET and Parafeed given that all of the above is observed. So for me there's little point in the extra complexity of Parafeed unless you want to take advantage of the bass boost possibility. Others will argue the opposite and I respect that ... like I say, both can be made to sound just as good as each other!

Naz

 

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