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Knight KA 95
Knight KA 95
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Old 19th July 2018, 11:40 AM   #11
sony6060 is offline sony6060  United States
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Actually Mullard mesh plate EF86. I changed to Mullard solid metal plate as many stated sounds better. I have bid on 1950 Valvo & 1960s Telefunken chrome plate EF86 tubes. I also changed the 12AY7 GE center bump plate to NOS 12AY& GE box plate as others stated the box plate is best sounding.

The amp was partly recapped in 1982 per receipts. Values were all wrong and too low. I have new caps and will install tonight. I went from stock values of 20uF to 120uF on the GZ34s and 60uF to 440uF capacitor thru a 150 ohm resistor supplying the EL34s. Rest of caps are 40% higher except last 5 caps that are same value as factory stock (30uF). A lot of capacitors in this amp. I will fire up tonight. Russian K40Y-9 coupling caps are on order. These caps will take the amp to another level in performance.

Last edited by sony6060; 19th July 2018 at 11:43 AM.
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Old 19th July 2018, 12:12 PM   #12
scottpetersen is offline scottpetersen  United States
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The first cap off the 5AR4(GZ34) should not be greater than 40mfd, unless there is a choke (or resistor) between them
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Old 19th July 2018, 12:18 PM   #13
sony6060 is offline sony6060  United States
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All the tube data I read stated max of 60uF. Where did you get the 40uF value?
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Old 19th July 2018, 11:49 PM   #14
6A3sUMMER is offline 6A3sUMMER  United States
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How about these:

https://frank.pocnet.net/sheets/093/5/5AR4.pdf GE 5AR4: Capacitor input filter: 40uF (scroll down to the next to last chart at the bottom). 200 Ohms per plate (1/2 secondary DCR + R = 200 Ohms). 160 mA DC maximum output

https://frank.pocnet.net/sheets/035/5/5AR4.pdf Amperex 5AR4: Capacitor input filter: 60uF 200 Ohms per plate (1/2 secondary DCR + R = 200 Ohms). 550Vrms maximum per plate (1100Vrms center tapped maximum) Rating chart at the bottom (page 5) 160 mA DC maximum output Even though GE lists 60uF, they still have maximum 160mA DC load.
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Old 20th July 2018, 12:09 AM   #15
sony6060 is offline sony6060  United States
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Thanks
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Old 20th July 2018, 12:43 AM   #16
45 is offline 45  Italy
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Quote:
Originally Posted by sony6060 View Post
I just bought a Knight 95 and will restore. It has UL connected EL34 power tubes. Anyone have any experience with this rather rare amplifier?
As I said in the other thread it's anything but rare. Have a look at the Mullard 5-20....

Twenty-Watt Amplifier
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Old 20th July 2018, 12:53 AM   #17
sony6060 is offline sony6060  United States
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Only seen a few KN95 on ebay for sale last 6 months. Many are the same old beat up dogs no one wants. I have seen 100s of Dynaco ST-70. The Knight KA95 I believe only had a production year of 1962 to 1963. I believe Allied went with Japanese imports for their line after 1963.

Last edited by sony6060; 20th July 2018 at 01:23 AM.
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Old 20th July 2018, 01:33 AM   #18
45 is offline 45  Italy
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It doesn't matter. It's a (bad) copy of the Mullard, IMHO. So if you want to know how it works in detail or play with it have a look at the Mullard....
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Old 20th July 2018, 01:44 AM   #19
sony6060 is offline sony6060  United States
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The Knight is a direct copy of the mallard circuit. EF86 pentode driving a twin tail phase splitter. Operates the EL34 in ultra linear like the Mullard 520 circuit. I can also change it to pentode operation by lowering resistor R128 for 400 volts on the EL34 screens. The 6600 primary impedance is great for pentode operation as it unloads the EL34s and unloading the plate to plate impedance has always resulted in better sound per my experience. It uses a 12AY7 phono amp into a 12AX7 tone control. 12AY7 is a serious tube. It used a pair of Mullard GZ34 that is more than adequate to power the amp unlike the Dynaco ST-70. I read the audio output transformers are very good. They have been robbed for other amplifiers. So, even though it is a lowly Knight name, I think it is a serious contender. If it does not play it goes. I already have great sounding gear.

After electrolytic capacitor replacement, I will take first listen. I know it will not impress me, but I will get an idea of its sound. Then, I will replace every coupling capacitor including the important tone controls with Russian K40Y-9 paper in oil. I know it will be good after that, but will it be great? I will find out. Takes 30 days to get those K40Y-9 though.

I also read the audio transformers are based on the Knight 60 amp series. Tests show a class A rating. Only a few vintage amps have a perfect Class A audio transformers. Unfortunately, the KN95 has not been tested to ensure class A audio transformer operation. See this web site for vintage audio transformer tests. Push-Pull Transformer Test

I have four Mullard EL34 xf1. four Genelex Gold Lion KT77 and four Svetlans Wing C EL34. I have GE box plate 12AY7, 1960 Mullard EF86 mess plate, 1970 Mullard solid plate, old stock Tesla EF806S, and perhaps win Telefunken chrome plate & Valvo D getter EF86s on ebay. 12AX7 are RCA 12AX7 black plate and Mullard 12AX7 long plate. I will also try Sovtek 12AX7LPS in the phase splitter only. I should find a good combination of tubes for best sound. Most state the new Genelex KT77 will outperform the other EL34 tubes.
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Old 20th July 2018, 07:53 AM   #20
45 is offline 45  Italy
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Speaking of EL34 I have yet to find one type that will outperform the original Philips. I have only a used pair, testing new, made in 1960's with dark brown base. No other EL34 has had the same performance, been able to withstand incredible abuse and after go back to work as nothing had happened. It's the only EL34 that has been able to survive, actually pass with flying colours, guitar amp tests up to insane levels. I have never found another vintage or current EL34 even remotely close....

From the point of view of performance I have found the tipped glass EI to be very good but a lot of these show red plate when power dissipation goes above 21-22 W. First production of chinese Golden Dragon, from 1990's, were also very good performance wise but some tubes failed if put under stress (G2 voltage above 400V). Current production Gold Lion seem to be quite good.

The KT77 was made precisely for UL application. I would go with the 77. Never found anything special in the Mullards. You might keep them as collectibles and speculate on their future value or even sell them now at premium price....
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