Author Topic: QUAD II (old old stock): Alternatives to KT66?  (Read 8786 times)

Offline charles

Re: QUAD II (old old stock): Alternatives to KT66?
« Reply #30 on: May 27, 2019, 03:54:37 PM »
Regarding the Quad II/22 Instruction books:

I have 4 original ones, all different issues.

There are differences in some of the issues.
It makes good reading.

One of the issue states: "The performance specification is fully maintained with random valve
replacements from standard commercially tested valves without matching or alignment of any
kind" 

This issue refers to the following Valves: 2 x EF86, 2 x KT66, 1 x GZ32

Offline fredeb

Re: QUAD II (old old stock): Alternatives to KT66?
« Reply #31 on: May 30, 2019, 06:17:47 AM »
 :popcorn:

I love all the information from this thread  :)
...evolution is the gradual development and stratification of progressive series of wholes, stretching from the inorganic beginnings to the highest level of spiritual creation.
Jan Smuts

Offline El Sid

Re: QUAD II (old old stock): Alternatives to KT66?
« Reply #32 on: May 31, 2019, 10:55:02 PM »
One of the issue states: "The performance specification is fully maintained with random valve
replacements from standard commercially tested valves without matching or alignment of any
kind" 


This issue refers to the following Valves: 2 x EF86, 2 x KT66, 1 x GZ32

Ooh that kind of talk could get you burned at the stake for heresy on some forums

Offline Ampdog

Re: QUAD II (old old stock): Alternatives to KT66?
« Reply #33 on: June 01, 2019, 04:09:13 AM »
One of the issue states: "The performance specification is fully maintained with random valve
replacements from standard commercially tested valves without matching or alignment of any
kind" 

Charles,

When was that book published?  I bet one can no longer make that statement for valves over the last two decades!
Audio must be the only branch of engineering where lack of basics' knowledge is considered a superior form of wisdom. (Anon)

Offline charles

Re: QUAD II (old old stock): Alternatives to KT66?
« Reply #34 on: June 02, 2019, 09:43:05 PM »
Ampdog,

Only a reference number, no date.

Possibly the very first edition. Completely different from the other ones.
On the cover is a photo of the Quad II/22. Installation information in inches,
the other issues in inches and mm.

All the other ones have Issue numbers with dates.

Offline HH NS1000

Re: QUAD II (old old stock): Alternatives to KT66?
« Reply #35 on: May 16, 2020, 01:50:06 PM »
Anyone have any KT66ís Iím rebuilding a set of Quad llís.
If you don't understand your own perceptions you cannot really make any sensible judgements.....or should I say you would not really fathom the conclusions you come to.

Offline Ampdog

Re: QUAD II (old old stock): Alternatives to KT66?
« Reply #36 on: May 17, 2020, 04:54:13 AM »
HH NS1000,

I may be repeating: did not reread the entire thread. The difference between 6L6GC (5881) and KT66 is smaller that the spread in characteristics of either. Replicas in appearance may be more attractive. but are also often significantly more expensive. I have long since stopped bothering about this and am using 6L6GCs for years now. Your money; your taste. (As stated earlier 5881s are also suitable - just; this regarding anode dissipation. bit I have found some 5881s to be more expensive than 6L6GCs!)

(Further repetition: Many Russian KT66s are using the exact same innards fir KT66 and 6L6.) Also bringing forward other perhaps misconceptions: The use of more powerful valves: The output power of an amplifier - all else being the same - depends on the voltages/currents available. It is utter nonsense to replace KT66 with EL34 or even more ridiculous, with KT88s, and only taxing the power transformers more. (What will 'they' do next - try KT120s?)   
Audio must be the only branch of engineering where lack of basics' knowledge is considered a superior form of wisdom. (Anon)

Offline HH NS1000

Re: QUAD II (old old stock): Alternatives to KT66?
« Reply #37 on: May 17, 2020, 01:13:08 PM »
Thank you for your reply I have now heard the same from some other esteemed forum members.
If you don't understand your own perceptions you cannot really make any sensible judgements.....or should I say you would not really fathom the conclusions you come to.