freestompboxes.org

@Manfred - what about an AC sweep sim then
I am sure you will see that the Musicman circuit with any of those transistors is totally unsuitable for use in this project
My sims show almost identical frequency response curves to the 1N4148 diodes - I merely posted the MM snippet to show that using base emitter junctions of transistors is not a new idea, as this amplifier was in production in the early 80s.
Like wise you are fairly unlikely to see any difference with a single frequency signal interactive simulation but the AC sweep analysis across the bandwidth reveals a completely different story
have fun
bajaman

Bajaman, did you by any chance sim ZTX 653, ZTX 450 or ZTX 550? Those seem to be the only Zetex devices available in my country and RS doesn't ship here. Have you tried MJE253 in real world? Those should be available as well.

It would be cool (albeit a bit of an overkill) to build the pedal with a DPDT switch wired to each clipping section and have the clipping diodes switchable between stock and something else (maybe the Zetex?). That's 8 different combinations.

Can't wait for my board to arrive to dig into it

Cheers

Thank bajaman! I will apply ZTX951 and BAV99 then I will choose one that sound good to me.

And can you introduce any other overdrive/distortion pedal that use BJT clipper?

bajaman wrote:

ZTX951 clippers.JPG

also worth consideration are the ZTX851 and ZTX849 npn transistors - again connected with reversed base emitter junctions.
The ZTX849 is the flattest simulation yet - beats the ZTX951 by reducing the slight mid peak by 1 dB, although this would be difficult to hear in practice
Both the ZTX951 and ZTX851 devices are available http://www.rs-components.com if you are having any difficulty sourcing them from your local
cheers
bajaman

Bajaman, did you by any chance sim ZTX 653, ZTX 450 or ZTX 550

hello Bancika
Yes - sim with ZTX653 will give a mid boost of 7.5db around 1k7Hz region, but still not as bad as 1N4148 - half way between and lower frequency boost which may be enough to avoid squeal
ZTX450 adds even more boost - a further 6db above the ZTX653 and shifts the centre to 2.5kHz
ZTX550 - slightly less than the ZTX450 and peaks slightly lower around 2kHz
If you cannot get ZTX849, ZTX851 or ZTX951 devices then the next best option would be the ZTX653 I suppose
cheers
bajaman

Thanks, bajaman. Very interesting info!
In that case, it looks like MJE253 is the closer to the "holy grail", no?

In that case, it looks like MJE253 is the closer to the "holy grail", no?

No - slightly worse than ZTX653 but better than the other two Zetex devices.
I have ordered some ZTX851 which have a similar almost flat response compared to the ZTX951, but because they are npn devices only half the price here in New Zealand.
I will report my findings in this thread once i have received and tried them.
all the best
cheers
bajaman

"If you don't want to risk toasting them with your iron I think you can isolate them enough if you remove C12 and R12.."

Thanks, but no issues brother. I was a Sr. Tech when I started my career and have the same equipment I have at home (PACE SensaTemp Wave Solding Station) as I did when I used to work for United Technologies and desolder and solder SMD components by hand....no issues, but thanks for the heads up!

"I think we may be getting the ! or i confused with a 1 like alkuz1961 pointed out.. that looks like a manufacturer logo."

"YES - the schematic that yellowboy and pakrat and the board that bugg has provided is CORRECT and true to the actual Friedman BE-OD circuit"

k. Thanks for the confirmation then and it's just a matter of best suitable thru-hole components to use in place of the BAV99, or whatever it is...but that is based on if that component is in fact a BAV99. Do we need to confirm this and then match up a similar thru hole component or is the ZTX951 just confirmed as should have the ideal characteristics we're looking for?

"I would strongly encourage those wishing to build this pedal to purchase one of bugg's excellent boards (still waiting for mine to arrive bugg ) and try the ZTX951 pairs - you could even fit a small toggle switch to switch between the diodes and the transistors."

Yes, it's definitely a case of adding a switch or ad least pins so you can swap components in and out to see what people like. As I said the tone I heard was very, very nice and only the noise issue a problem. Eliminate that and I would be happy. Add an even better component and that's just the whipped on the cake for me! Not that it's a matter, but huge difference in pricing between ZTX951 and 1N4148...$1.02 v. $0.10!!!

"What about using an NPN instead of a PNP???"

Always a possibility, but not advantageous in my opinion. Why?? I've played with and HEARD circuits over the last 10 years or so, both amp and pedals. PNP...ALWAYS,always, always "sound" better to my ears in my opinion! I personally will not put NPN in.

"I will apply ZTX951 and BAV99 then I will choose one that sound good to me."
" have ordered some ZTX851 which have a similar almost flat response compared to the ZTX951, but because they are npn devices only half the price here in New Zealand. I will report my findings in this thread once i have received and tried them."

Awesome job guys. Looking forward to the continued feedback and getting mine finally going. I'll order parts today. I wonder if I can get those Veroboards going swapping out components? As I said way back in the thread, I'd like to get a MIDdle control added also since Friedman (or EDI) left one out.

Alright, everything checks out. All PCBs will be shipping today.

I have plenty more so can ship them immediately without delay now.

bajaman wrote:@Manfred - what about an AC sweep sim then
I am sure you will see that the Musicman circuit with any of those transistors is totally unsuitable for use in this project
My sims show almost identical frequency response curves to the 1N4148 diodes - I merely posted the MM snippet to show that using base emitter junctions of transistors is not a new idea, as this amplifier was in production in the early 80s.
Like wise you are fairly unlikely to see any difference with a single frequency signal interactive simulation but the AC sweep analysis across the bandwidth reveals a completely different story
have fun
bajaman

Sorry, I see, you are right.
I gave a hasty reply.
I deviated from the theme, my focus has been on the Musicman circuit.

No problem Manfred
all the best
bajaman

Manfred wrote:

bajaman wrote:@Manfred - what about an AC sweep sim then
I am sure you will see that the Musicman circuit with any of those transistors is totally unsuitable for use in this project
My sims show almost identical frequency response curves to the 1N4148 diodes - I merely posted the MM snippet to show that using base emitter junctions of transistors is not a new idea, as this amplifier was in production in the early 80s.
Like wise you are fairly unlikely to see any difference with a single frequency signal interactive simulation but the AC sweep analysis across the bandwidth reveals a completely different story
have fun
bajaman

Bipolar transistors(BJT) are not the only devices that can be connected as diodes.

refer to this link:
https://en.wikipedia.org/wiki/Diode-con ... transistor

A diode-connected transistor is a method of creating a two-terminal rectifying device (a diode) out of a three-terminal transistor.
A characteristic of diode-connected transistors is that they are always in the saturation region for MOSFETs and in the active region for BJTs.

A diode-connected transistor is made by:
connecting the base and collector of a BJT
connecting the drain and source of a JFET[1]
connecting the gate and drain of a MOSFET

Diode-connected transistors are used in current mirrors to provide a voltage drop that tracks that of the other transistor as temperature changes.[2] They also have very low reverse leakage currents[3]

I intend to explore the sound qualities of ALL of these when my pcbs arrive.

it will also be interesting to check out different op-amps. TL072 is so vanilla People get obsessed with opamps in tubescreamers.
I have a few different dual opamp types leftover from experimenting with Timmy circuit, I'll give them a try here.

Cheers

Hi,

I have an issue with mine, crafted this morning. True bypass is OK, but no sound when ON. R22 heats so much that film has burnt (0.6W metal film 10 Ohms) and is desoldered after a few seconds. 8.9V before R22, 1,8 after. The 4 circuit LED doesn't light (the indicator one does).

Any idea ? Bad R22 (measured at 10 ohms) ?

Most likely you have a dead short so check the circuit till you find it.
The leds across the signal won't light up like the indicator led, they are there for there diode function not light function.
Phil.

Any update(s) in regard to different components used yet??

My parts should arrive today! I'll start populating the Buggs board as it is verified now and add pins so I can swap in and out components in regard to BAV99's. I hope this time this f*cker works! Good lord, long 2 months trying to get something to work and quiet!! Wish me luck.

rmroza wrote:Any update(s) in regard to different components used yet??

My parts should arrive today! I'll start populating the Buggs board as it is verified now and add pins so I can swap in and out components in regard to BAV99's. I hope this time this f*cker works! Good lord, long 2 months trying to get something to work and quiet!! Wish me luck.

You should start with a simpler circuit.

https://buildyourownclone.com/collectio ... r-packages

bajaman wrote:

ZTX951 clippers.JPG

also worth consideration are the ZTX851 and ZTX849 npn transistors - again connected with reversed base emitter junctions.
The ZTX849 is the flattest simulation yet - beats the ZTX951 by reducing the slight mid peak by 1 dB, although this would be difficult to hear in practice
Both the ZTX951 and ZTX851 devices are available http://www.rs-components.com if you are having any difficulty sourcing them from your local
cheers
bajaman

So for this mod you're using 4 ZTX951's in pairs tied by their base and emitter?

We can wait for a response, but yeah, it would be the Base to Emmiter breakdown I believe

ZTX951's are BJT PNP, to the bases would go together and emitters out.

For NPN, again use B-E, but emitters go together and bases out (like MPSA06's in the BE-100 amp).

Correct??

So for this mod you're using 4 ZTX951's in pairs tied by their base and emitter?

We can wait for a response, but yeah, it would be the Base to Emmiter breakdown I believe

ZTX951's are BJT PNP, to the bases would go together and emitters out.

For NPN, again use B-E, but emitters go together and bases out (like MPSA06's in the BE-100 amp).

Correct??

NO

HINT: read the thread before making the wrong assumptions

GO BACK TO PAGE 17 of THIS thread and READ THE DIAGRAM 13 posts down

Only one pair of transistors is required
bajaman

Well, fuck me! It was a good guess thou!!