LITE 2 PARALLEL/DRIVE

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kanj
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Re: LITE 2 PARALLEL/DRIVE

Post by kanj »

Geoff 1965,

Thanks for the recommendations, posting all your experimenting, and all the advice for this ....and all your other replies & answers to my numerous newbie questions!

As you have written before, being new to this and trying to really understand what's going on has certainly "popped" some brain cells along the way.... hopefully I'm starting to understand a little more also.

Thanks very much,
kanj
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geoff 1965
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Re: LITE 2 PARALLEL/DRIVE

Post by geoff 1965 »

Kanj,
yeah i'm going to rest my remaining brain cell's now and just play my guitars!
best of luck with your build
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Re: LITE 2 PARALLEL/DRIVE

Post by geoff 1965 »

Pilgrim's
finished the last tweak to the drive stage resistor! this will depend on the pickup output of your guitar,my strat has 6K ohms and the guitar with humbucker's has 9K neck and 16K bridge so i've used 400K as a nice balance between the two.
here's the updated schematic and layout.
PREAMP LAYOUT.jpg
PREAMP.jpg
pin layout.jpg
thank's to ZP and the guys who worked on the parallell/cascade mod,that was a useful reference.
Big thank's to Curtiss and Rockmumbles for their help and good advice.
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Re: LITE 2 PARALLEL/DRIVE

Post by geoff 1965 »

Hello pilgrim's
just posting an update for the preamp cathode biasing,i settled at 1K5/.68uf on the 1st triode and 1K5/3.3uf on the 2nd which was good for both parallel and drive and cured the "mushiness" i was getting with the drive signal but i was'nt 100% happy with the parallel,it was a bit "thinner" sound compared to 25uf on each cathode. so after hours of testing again i've found a better solution with 2K2/1uf on the 1st triode and 1K5/10uf on the second and i have a nice full tone on the parallel and the same on the drive signal with good bass response with no mushiness.plate voltage is 152 parallel so the 2K2 raises it by around 12 volts.
Last edited by geoff 1965 on Thu 06/28/18 6:59 pm, edited 1 time in total.
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geoff 1965
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Re: LITE 2 PARALLEL/DRIVE

Post by geoff 1965 »

Hello,
i've finished the final tweaking to the cathodes and gain stage on the cascade/parallel mod! i added a dpst switch for the cathodes so i could switch between film and electrolytic caps,the 1uf/3.3uf film caps are superb for response and clarity especially on the gain stage but on parallel you lose the warmth you get with the higher value electrolytics.
i initially tried the standard 50uf/820 on the second half of the switch but the shared cathode was no good cascaded,i was getting a kind of "motorboating" effect so eventually settled at 10uf electrolytic on the 2nd triode which has turned out to be good in both parallel and cascade.with using the 10nf to volume pot cap instead of the standard 4n7 anything above 20uf on the cathode creates "mushiness" when cascaded.
just a quick note regarding the gain stage,the series resistor in the gain stage was quite a challenge,i was getting the best tone/clipping from the lower value 220 & 280K values but the signal was too high so i used a 400K to reduce it which worked but altered the tone.so thank's to you guy's and learning about voltage dividers i went back to 220K for the best tone and added a 220K divider which has worked perfectly! got some very good tones and level of drive now.
GAIN STAGE.jpg
NEW CATHODE BIASING.jpg
011.JPG
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Re: LITE 2 PARALLEL/DRIVE

Post by JMPGuitars »

Wow, that WIMA cap looks a lot bigger than I was expecting!
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geoff 1965
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Re: LITE 2 PARALLEL/DRIVE

Post by geoff 1965 »

ha! ha! yeah Josh, it's 100V rated the same as the mallory next to it! i don't think i'll get any leakage problems with the cathode voltage trickling through it,the tone & response from that is superb.
notice i fitted another turret board for the new cathode and cascade layout,made things a lot easier.
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