# Building an M800 (PAL800).. should I do any changes to improve it?



## Idroj (Dec 3, 2020)

Hi I'm starting an M800 (PAL800) and would like to know if the J201 transistors is the absolute best transistor choice for this pedal. I read something somewhere about a "Slash Mod" but can't find it anymore... any other change you suggest? I'm after that Marshall / Slash / JCM800 sound..  It'll probably never sound like the real thing but I'd like to get as close as I can get...

Thanks!


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## BuddytheReow (Dec 3, 2020)

You can use these J201s here. They dont make the regular shape like you see with other transistors, however they do still make the SMD. I asked this very same question about the J201s






						J201 Substitute
					

Ordered some j201s from smallbear last week. They got back to me today and said they had a website error and are all sold out. They offered a refund or to replace them with j112 or pf5102. Are these good substitutes? Trying to vero a dr boogie and warhead x2 amp in a box. Also wanted to have...



					forum.pedalpcb.com
				












						MMBFJ201 JFET (Pre-Soldered) - PedalPCB.com
					

JFET




					www.pedalpcb.com


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## BuddytheReow (Dec 3, 2020)

Build the board as is first. You want to make sure it works normally before you start modding it


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## Idroj (Dec 3, 2020)

I found the J201s (regular shape) on eBay from Oregon.. They look normal.. hopefully aren't fakes..
Yes, I should build it normal first, I'm getting ahead of myself.. ?


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## phi1 (Dec 3, 2020)

Definitely socket the jfets! eBay j201s are notorious for often being fake (way out of spec). 

Personally if using the eBay ones I’d recommend measuring the Vp and Idss.

I’ve used this layout to measure (updated version, with no op amp).








						Greatly Improved JFET Matcher
					

Collection of vero (stripboard) & tagboard layouts for 100s of popular guitar effects, with over 500 verified designs. DIY your own boutique effects!




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## BuddytheReow (Dec 3, 2020)

In general, stay away from ebay unless you absolutely know the seller. There are more fakes than anything else. If its too good to be true (price included) it probably is...


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## Idroj (Dec 3, 2020)

phi1 said:


> I’d recommend measuring the Vp and Idss


Is this something a beginner pedal builder can easily do? ?


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## phi1 (Dec 3, 2020)

Well... I think it’s doable buy reading the layout I linked, but maybe not most beginner friendly project, especially if you’ve never built on vero board. It’s a small layout, but you’re likely to run into several questions. I could give you some pointers. But, the easiest way would be to buy the presoldered smd j201s from pedalpcb (linked by buddy).  You can always come back to measuring the eBay parts when you have more experience with vero / multi meter etc.


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## Idroj (Dec 3, 2020)

Good idea, I'll do that.. thanks!  I see that the presoldered ones have 3 holes.. how do I install them? can they be socketed?


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## phi1 (Dec 3, 2020)

Use some resistor leg clippings to make legs for it. Then you can solder the legs to the board or insert in a socket.

I know it’s kind of a bit of work since there’s 6x on this build. To me, knowing I have good parts is worth the extra clipping and soldering.


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## BuddytheReow (Dec 3, 2020)

Patience here is rewarded


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## Chuck D. Bones (Dec 4, 2020)

Idroj said:


> I found the J201s (regular shape) on eBay from Oregon.. They look normal.. hopefully aren't fakes..
> Yes, I should build it normal first, I'm getting ahead of myself.. ?


I'm taking wagers.  I'll bet a 6-pack that none of them meet spec.


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## Chuck D. Bones (Dec 4, 2020)

Idroj said:


> Is this something a beginner pedal builder can easily do? ?


Yes, if you have a DMM and a 9V power source.  If you're going to buy transistors on eBay, then being able to test them is an essential skill.



Idroj said:


> Hi I'm starting an M800 (PAL800) and would like to know if the J201 transistors is the absolute best transistor choice for this pedal.



PF5102 should work in this pedal, you can get them from Small Bear, they will cost less than the crap on eBay and will be the real deal.  For maximum gain, you want ones with a low Vp for everything except Q4.  Q4 can have any Vp that's in spec.


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## Mcknib (Dec 4, 2020)

I've got about 40 odd through hole J201's left - if you gimme one of your arms, or a leg, or both I'll send you 1 per limb.......

Alright 2 then


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## Idroj (Dec 4, 2020)

Mcknib said:


> I've got about 40 odd through hole J201's left - if you gimme one of your arms, or a leg, or both I'll send you 1 per limb.......
> 
> Alright 2 then


I need 6 and only have 4 limbs, what should I do? ?


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## Idroj (Dec 4, 2020)

I also bought 4x 2N5088 from the same eBay seller and those I installed on my Muffin Fuzz.. Now I'm not looking at the muff the same ?
Thank god I socketed them... I may have to test them or buy new ones and compare?


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## Idroj (Dec 4, 2020)

Should I buy one these Transistor Testers to verify these J201s and 2N5088s I got from ebay, and other future transistor purchases? Do these provide accurate and reliable readings?


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## Mcknib (Dec 4, 2020)

Idroj said:


> Should I buy one these Transistor Testers to verify these J201s and 2N5088s I got from ebay, and other future transistor purchases? Do these provide accurate and reliable readings?


Always handy for checking components I've got the DCA55 and one of these, the DCA doesn't fully check FETs just gives the type N or P and Gate

The cheap one identifies all FET pins and gives VGS

Most results between the DCA and this one are fairly close

For the money it's excellent you can test a lot more than you can with the DCA55 inductors, caps etc

I bought this one









						Mega328 Lcr-t4 ESR Transistor Tester Diode Triode Capacitance SCR With Case for sale online | eBay
					

Find many great new & used options and get the best deals for Mega328 Lcr-t4 ESR Transistor Tester Diode Triode Capacitance SCR With Case at the best online prices at eBay! Free delivery for many products!



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## Chuck D. Bones (Dec 6, 2020)

I have a similar one, paid around $20US.  I use it all the time.


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## perfboarder (Dec 6, 2020)

Me too. LCR T4 is cheap big help.
Dont forget to buy the case and update firmware. Easy to do with arduino.

If want LCR with adaptor, just solder dc jack and use positive center adaptor. No more waste battery. Cmiiw


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## Idroj (Dec 6, 2020)

Got the presoldered J201s from pedalpcb ?✅


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## DrumBuster (Dec 9, 2020)

Chuck D. Bones said:


> Yes, if you have a DMM and a 9V power source.  If you're going to buy transistors on eBay, then being able to test them is an essential skill.
> 
> 
> 
> PF5102 should work in this pedal, you can get them from Small Bear, they will cost less than the crap on eBay and will be the real deal.  For maximum gain, you want ones with a low Vp for everything except Q4.  Q4 can have any Vp that's in spec.


Sorry for bumping this thread but a fellow member recommended me to ask you, I got some generic J201s from Small bear, they don’t seem to be on spec, do you recommend me getting the PF5102 from the same seller? Do they highly differ on tone?


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## Chuck D. Bones (Dec 9, 2020)

Can you be a little more specific, what about the "generic J201s" are out of spec?  Which pedal are you building, the M800? 

I recommend that you *read this* if you haven't already, it might answer your questions. Subbing JFETs might alter the tone, depends on the circuit and how you dial-in the bias.


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## DrumBuster (Dec 23, 2020)

Chuck D. Bones said:


> Can you be a little more specific, what about the "generic J201s" are out of spec?  Which pedal are you building, the M800?
> 
> I recommend that you *read this* if you haven't already, it might answer your questions. Subbing JFETs might alter the tone, depends on the circuit and how you dial-in the bias.


Sorry, didn’t get a notification. Small bear sold them as “generic j201”, which scares me a lot. I swapped a horribly out of spec for a pf5102, I now have “noise”.


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