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ZKit2 alternative parts question (Read 5245 times)
Rusty
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ZKit2 alternative parts question
01/20/16 at 01:05:29
 
Hi,

Can someone recommended a replacement for Metal Film Resistors - Through Hole 1/2watt 2.7Kohms 2% and Wirewound Resistors - Through Hole 300ohms 5% 5watts as I'm unable to find any

Thanks, I'm not confident enough to make an informed choice on alternatives.

Thanks Mark

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Rusty
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Re: ZKit2 alternative parts question
Reply #1 - 02/02/16 at 03:03:10
 
As there has not been a reply I'll move on.

Thanks anyway
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Core32
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Re: ZKit2 alternative parts question
Reply #2 - 02/02/16 at 12:18:02
 
Sorry. Just saw your posting.
When you say "replacement" do you mean a place to buy those particular parts, exactly as specified?
Or are you looking to replace the "type" resistor they are?
(I wouldn't know why but thought I would ask.)

I use Antique Electronic Supply for most of my discrete components: https://www.tubesandmore.com/products/resistors

2.7K 1/2W MF  1% =  R-M2D7K
300 ohm WW 5W 5%  =  R-Q300

If you use their value select dropdown on each type you should be able to find these part numbers.
Not expensive at all. You can of course spend a ton more but for this kit I think these prices are about right.

You can also try Mouser but I try to support the shops that cater to the tube DIY crowd.  :)
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Rusty
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Re: ZKit2 alternative parts question
Reply #3 - 02/03/16 at 04:12:16
 
Thankyou, I couldn't find the two parts listed and I didn't want to substitute them without asking first.

I'll check out tubesandmore.

Cheers,
Mark
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Tempest2k8
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Re: ZKit2 alternative parts question
Reply #4 - 02/25/16 at 02:02:49
 
If my speakers are 8 Ohm, could I use GXSE10-8-8K instead of 10-6-8k?
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Core32
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Re: ZKit2 alternative parts question
Reply #5 - 02/25/16 at 02:16:40
 
I don't doubt you could but it would limit the range of speaker impedance the 10-6-8K is centered around and I don't doubt Steve has set this amp design up to match that 6 ohms.
They are the same price so I would ask why change up a tested and proven combination?
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Tempest2k8
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Re: ZKit2 alternative parts question
Reply #6 - 02/25/16 at 03:35:17
 
It's been 30 sumthing years since I did any design and very little tube even then. But I seem to remember something along the lines of max power output when the load resistance equals the source. I may have this out of context, which is why I asked. But the output impedance of the transformer in the parts sheet is 6 Ohms. My speakers are 8 Ohms, so theoretically the best output would be achieved with an 8 ohm transformer & my 8 ohm speakers. I guessed the 6 ohm would be for a variety of speaker resistances, 2,4,8 & would be a good general part.

Hoping to stimulate my brain cells again and build a couple of these for fun.

Chris
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Core32
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Re: ZKit2 alternative parts question
Reply #7 - 02/25/16 at 12:55:09
 
I'm sure you are correct on the impedance matching.
And for sure Steve wanted the great little amp to be able to drive a range of speakers.
If you think you are always going with 8 ohm speakers then I don't see a problem changing it.
I need to read back through some of Steve's design write ups though because I have a faint memory why there may be another reason for the 6 ohm output.
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Tempest2k8
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Re: ZKit2 alternative parts question
Reply #8 - 03/04/16 at 15:50:58
 
I think I found the answer. Thanks for pointing me in the direction to look.

"I also choose a single 6 ohm tap because I found the single tap prototypes sounded better than the multi-taps, something about the unused taps.  The primary impedance is 9800 ohms with 2850 winds.  This makes the el84 and SV83 tubes couple more power as the speaker impedance drops.  Max power is at 2 ohms."
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Core32
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Re: ZKit2 alternative parts question
Reply #9 - 03/04/16 at 16:12:39
 
That's the one.
And for what it's worth I used the 6 ohm output transformers in my DIY builds and my speakers are 8 ohm rated.
No regrets here. Good luck!
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