freestompboxes.org

thetragichero wrote:hey it works! and it's LOUD!
bass control isn't doing anything but the bass is in a state where I'm okay with that. treble control has a lot of range, from slightly dull to almost shrill - I like it!

I don't have a 'clean' bass amp (not really my style), so I will have to wait to hear it through the DI at church

but this old has some new life!

good - did you use 2N5457 ?
check your pot wiring - the bass control range should be huge - are you using 250k pot ?
check that you are using 100n, 47n, 100k and 8k2
keep going
cheers
bajaman

2n5457, made the necessary resistor changes
250k log pot (I think I just realized from the schematic that key=b means linear...it's push/pull to give series/parallel for the neck humbucker so I'll have to live with a non-ideal taper... I imagine bass would mainly be set and forget anyway, unlike treble that I can tweak several times per song if required)

if i'm reading the schematic correctly, the bass control is setup like a variable resistor/rheostat (only wiper and one of the lugs used) as opposed to a potentiometer (wiper and both lugs used), yes?

it's bedtime anyway

thetragichero wrote:if i'm reading the schematic correctly, the bass control is setup like a variable resistor/rheostat (only wiper and one of the lugs used) as opposed to a potentiometer (wiper and both lugs used), yes?

I don't think that will make any difference. You'll just chamge the resistance between wiper and one lug anyway.

gonna give this another try with k117 (these look genuine). I think this will work better in my pbass with two dissimilar pickups than one of the original music man preamps...

(thinking of laminating some old solid cabinet doors together to make a (5 string) jbass body and I think that would work better... check back in like two years lol)

So I finally built and tested this one. I made the mistake of wiring both tone pots in reverse, since I'm not good on understanding tone stacks I go for the luck, it's a 50/50 chance of getting it right .

The first thing I must say is this is loud. So loud it easily distorted my amp when I turned the bass volume to the max. I didn't tested it too much because I used a guitar amp and don't want to abuse the speaker.

I'm still doing some tests because I found out this preamp is noisy when the treble is full. This is probably due to the bass I'm using have no shielding, so I removed the whole thing and I'm shielding it before test it again. But I had to post here to say this preamp sounds amazing, and I'll surely be putting it on the bass of some friends.

Is there a guitar version on your plans?

Ok, so I shielded the bass and played with this preamp a little bit more. This is a little beast and what I can say to all the bass players is to just build it! I loved the distorted bass sound I can get at full volume.

With a shielded bass and 9V battery, it's dead quiet. No noise at all. Mine is still noisy, but it's because I'm powering it with a 18650 battery along with a charge module and a MT3608 based step up module to get 9v out of the 18650 battery. I tried a few things to get rid of the noise, but with no luck. I'll probably just use a 9V battery. If I use one rated for 400mAh, one battery should last 5000h, which is a lot of time.

sourced some genuine 2sk117 Ys and built this for my pbass. this doesn't seem as loud as the other version, and I like that. I may have to revisit the bass with 2n5457 version to see where I went wrong, but I'm SUPER HAPPY with this in my #1 bass
tested the current draw. 46uA not too shabby!

thanks again!

Okay I'm maybe being a complete noob here hedged with a touch of paranoia because I'm forever ordering the wrong bits.

I've ordered the parts up for the 2N5457 version (Because I could get all the bits from one place without hassles). But I've read the schematic as having non-polarised Capacitors. BUT when I look at Jarno's layout and thetragichero's made up board I see polarised caps.

Have I screwed up or just being an undereducated noob and missed something?

TIA

Johnston_evo3 wrote:Okay I'm maybe being a complete noob here hedged with a touch of paranoia because I'm forever ordering the wrong bits.

I've ordered the parts up for the 2N5457 version (Because I could get all the bits from one place without hassles). But I've read the schematic as having non-polarised Capacitors. BUT when I look at Jarno's layout and thetragichero's made up board I see polarised caps.

Have I screwed up or just being an undereducated noob and missed something?

TIA

You can either use polarized electrolytic/tantalum caps or non-polarised ceramic or non-polarised electrolytics. I'd prefer to use ceramics.
When using polarised caps, just rotate them with + pointing to the the higher voltage.

Thanks for that. Thought I had cocked up.

I still have some Fender jack sockets kicking about when I ordered the ones for the FX loop rather than the input

Instead of 2N5457 can J201 be used?

perfector wrote: ↑20 Sep 2019, 09:53 Instead of 2N5457 can J201 be used?

no - not without altering resistor values
cheers
bajaman

What is this particular transistor arrangement called? I've seen it only once before (with another bjt as the n-type controlling device). It seems really interesting I'd like to do more research on it

asbestosaurus wrote: ↑11 Oct 2021, 09:00 What is this particular transistor arrangement called? I've seen it only once before (with another bjt as the n-type controlling device). It seems really interesting I'd like to do more research on it

the anti-symmetric pair

Hi Bajaman, is there an equivalent to the 2SK117(Y) witch is VERY difficukt to get here in Europe? Could also be an SMD-FET...
Thanx a lot
Harald from Austria

Hello, They are available, and in stock from: https://www.musikding.de/2SK117-GR

marsbel wrote: ↑17 Apr 2022, 11:42 Hello, They are available, and in stock from: https://www.musikding.de/2SK117-GR

NO!
watch what you say! seriously, it is the "GR" version, not good for this circuit...
as Bajaman said it multiple times, the "Y" version is needed for this application...

different "ending" (Y / GR / BL) mean different IDSS "range".... see in the datasheet...