🚀 go-pugleaf

"Arny Krueger" <arnyk@hotpop.com> wrote in message 
news:aaCdndTmqeSwuEnfRVn-1w@comcast.com...
> "Trevor Wilson" <trevor@SPAMBLOCKrageaudio.com.au> wrote in
> message news:42d41ed6@news.comindico.com.au
>> "Arny Krueger" <arnyk@hotpop.com> wrote in message
>> news:X4-dnZRDL_aHhknfRVn-tQ@comcast.com...
>>> "robert casey" <wa2ise@ix.netcom.com> wrote in message
>>>
> news:xOUAe.21856$eM6.10366@newsread3.news.atl.earthlink.net
>>>>>> it apart from cheap CD players. These include:
>>>>>>    Proper relay muting.
>>>>>
>>>>>
>>>>> Nothing magic about that. Just something mechanical to
>>>>> break.
>>>>>
>>>> A relay avoids any possible effects of the unmuted
> muting
>>>> transistors causing distortion because of nonlinear
>>> effects.
>>>
>>> But if there are no problems with distortion due to the
>>> muting transistors, then the relay is futile.
>>
>> **IF that is the case, then yes. However, a relay avoids
> the
>> possibility entirely.
>
> Well, until the contacts get dirty.

**Not even then. In any case, decent equipment uses hermetically sealed, or 
mercury wetted relays. These demonstrate phenomenal reliability. More 
importantly, is the fact that relays are almost always used to short the 
signal to ground. Dirty contacts (if they ever occur) will therefore be 
irelevant.

>
>> Muting transistors cause measureable  problems in many
> units.
>
> Never saw the problem even though I've read people get
> paranoid about it.

**And rightfully so.

>
>>Properly implemented relays cause no  problems. Ever
>
> Until the contacts get dirty. I've experience that problem
> with power amps.

**Indeed. Series relay contacts can be a problem. However, we're talking 
about shunt circuits.

>
>>>>>>    Decent output stage, which does not include
>>> primitive,
>>>>>> 4558-style output ICs.
>
>>>>> Nothing magic about that. Terevor, your phobia about
>>> 4558s
>>>>> isn't my problem.
>
>>>> Some op-amps can have crossover distortion issues.
>
>>> Yup in the late 60s and early 70s, but mostly not even
> then.
>
>>>> Don't  know about the 4558 specifically though.
>
>>> I do. It's widely used in consumer and pro audio gear.
>
>> **No. 4558 style chips have not been used in any decent
>> equipment since before 1980.
>
> OK, so all this fairly new  pro gear such as the power amp
> for my NHT Pro A10s is indecent. Either that or it was made
> before 1980 even though that  model came out just a few
> years ago.

**If it uses a 4558-style chip (and depending on how it is used), then it is 
crap. 4558-style chips have been available since the late 1970s. There are 
far better performing chips available. Such chips are inexpensive and have 
been available for decades. Be aware, that I have no issue with 4558-style 
chips as part of DC servo, or in LF circuits.

>
>> Even pro audio equipment
>> manufacturers stopped using them two decades ago. They
> were
>> resurrected by cheap Asian CD/DVD player manufacturers
> awhile
>> ago. Decent equipment eschews the use of them.
>
> I run into 4558s every once in a while in all sorts of gear.
> Just because Trevor is paranoid about them doesn't mean that
> everybody is.

**I'm not paranoid about them. They just have no place (outside DC 
functions) in decent audio equipment.

>
> Yes, 4558s aren't the greatest op amp in the world, but they
> are still being used to make quality new equipment.

**No, they're not. Their use is confined exclusively to cheap, Asian 
equipment, or to DC and LF functions. They are not used (and haven't for 
decades) for high quality equipment. Consumer or pro.


-- 
Trevor Wilson
www.rageaudio.com.au