Matchless Spitfire Questions

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Jonas Gemini
Hey get your own solder
Posts: 295
(2/9/04 6:55 pm)
 Matchless Spitfire Questions
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 Just need to start getting some information on the matchless spitfire from everyone.

1. I heard that the original outputs had 4000 ohm primaries for the two EL84 output tubes. Is there any truth to this?

2. I plan on using a tranny with about 6600 ohms, how would this effect the effeciency of the output tubes? I ask this because the original schematic shows about 350V on the plates, so I plan to use the EL84M/7189 type tube but would aslo like to know how the impedence mismatch really meansa and if I sould worry about this.

3. I have seen everything from 120 ohm 5watt/25uf to 120 ohm 15watt/250uf cathode resistors setups on the matchless EL84 type amps. What's going on here?

4. Any advice or changes to the schematic are diffenetely welcome here?

Much Ablidged
Jonas
 
ganzonimx
Hey get your own solder
Posts: 358
(2/9/04 7:36 pm)
 Re: Matchless Spitfire Questions
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 I read also about that mismatch, but I went better with a 8000 ohm OT for my Lighting. Tube data point to 8000 ohm. It might be flawed information, why should Matchless mismatch on the 2%%WORD26%„ and not mismatch on the 4%%WORD30%„ amps? Dave West sells at a decent price transformers that are suposed to be left overs from Matschless, you could buy the tranies there ore ask him about specs.

I had 365 volts on the plates and with a 125 ohm cathode resistor the tubes run at nearly at 15 W idle. With a 220 ohm they run a little cooler but still at 85% max plate dissipation. I'm waiting now for some zehners to put in to bring the voltage down. With a 330 Ohm resistor the idle current would be fine but there are nasty tonal changes when playing loud.

I would look in a seccond bult for a PT that gives a lower platevoltage to not cook the tubes to hard...

Cris

 
wayneosdias
Senior tube assistant
Posts: 230
(2/9/04 7:40 pm)
 asdf
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 Hey Jonas

I did the spitfire and then the lightning, both spinoffs of the marshall 18w blues breaker. Having built and played all 3 the 18w blows them away in terms of tone. Granted I used a 125e ot instead of a matchless tranny or the west lab repro tranny for the spitfire and a 1608 for the lightning, still I liked the 18w better and used both of the aforementioned trannies. Yes there is a Z mismatch on the spitfire which acounts for the the tone of the amp. I did this w/the 125 where it is very ez to manipulate 1ary and 2ary impedance, trying it both ways the lower Z made for a crunchier tone. You may want to look on blueguitar.org and look under articles, theres a interview of the founder of matchless and he goes into some about this "apperant miss wire". Also if you decied to step up to the lightning it uses the same tranny, keep in mind those pt/ot combos from westlab are not cheap. Ont the other hand the 18w circuit pushes the el84s very hard which accounts for the power stage distortion, and in my opinion, sounds more pleasing.

goodluck and you may want to try and page joguitar, he built a few w/the westlab trannies and freq'd this forum some time ago. He was very happy w/his spitfire/lightning builds.

wayne
 
wayneosdias
Senior tube assistant
Posts: 231
(2/9/04 7:43 pm)
 asdf
--------------------------------------------------------------------------------
 ohya,

i used the schems off schmatic heaven for both builds.

wayne
 
scole90
Junior tube assistant
Posts: 16
(2/9/04 11:57 pm)
 Re: asdf
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 i built my spitfire using the westlab trannys, i think the amp sounds incredible, im getting 352 volts on the plates, just a hair under 16w dissipation. it was recommended to me to put a 5k 5w resistor just before the two 100 ohm screens, this is supposed to cool the tubes down without sacrificing any tone.
 
ganzonimx
Hey get your own solder
Posts: 360
(2/10/04 10:40 am)
 Re: asdf
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 Hey Wayne

I searched for that article you mentioned at blueguitar.org, but coudn't find it - would you mind to post the link?

Thx Cris
 
wayneosdias
Senior tube assistant
Posts: 233
(2/10/04 10:55 am)
 asdf
--------------------------------------------------------------------------------
 Hey Cris, Howz Mex?

I just pulled up the article on blueguitar.org,but it wont post the httpaddress in the browser bar so I couldnt paste it here for you. Youll have to go to the site, hit ftp site map, scroll down and hit matchless and it should pop up. Didnt have time to reread the article but I think theres some info there re the ot Zed. if you cant find it there try going to 18watt.com and page zaphoidphil re matchless, hes got the skinny on the topic.

cheers
wayne
 
ganzonimx
Hey get your own solder
Posts: 362
(2/10/04 11:05 am)
 Re: asdf
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 Thanks Wayne, I found it!

the day is nice, sunshine, about 82ºF, I havn't seen any patients today, so I'm surfing the board ...

Cris
 
wayneosdias
Senior tube assistant
Posts: 234
(2/10/04 4:22 pm)
 asdf
--------------------------------------------------------------------------------
 Nice, its about 70 w/the sun shining here, but theres a nasty wind blowing down the surf. I had a few Pts remit to the hospital so my case load is light today.

cya
wayne
 
ganzonimx
Hey get your own solder
Posts: 363
(2/10/04 5:26 pm)
 Re: asdf
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 Wayne

am I right, assuming we'r from the same professional species?  

Cris
 
wayneosdias
Senior tube assistant
Posts: 235
(2/10/04 6:12 pm)
 asdf
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 No, Im not an MD, too much school. Im a PT and do alot of home health, alot of s/p thr, tka, cva stuff. So are you scratching your head askig why didnt you go the engineering path yet? I do everday i sit down and start messing w/my amps, hahah, just kiddin, I like health care alot, good rewarding career path.

Keep up the good fight Cris

wayne
 
Jonas Gemini
Hey get your own solder
Posts: 298
(2/11/04 12:12 am)
 Re: asdf
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 Thanks for all the information. I will keep in touch.

Jonas
 
 
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