Friedman BE-OD Pedal  [traced]

General documentation, gut shot, schematic links, ongoing circuit tracing, deep thoughts ... all about boutique stompboxes.
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bugg
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Post by bugg »

toneman wrote:
bugg wrote: I'm looking now, if I can come across one of these in the $150 range I'll buy it and we'll put an end to this madness.
there's one on Ebay right now for $149.99 + shipping
https://www.ebay.com/itm/FRIEDMAN-BE-OD ... 1438.l2649
Hey thanks! I saw that one, but was somewhat put off by the almost 3 week "Extended handling time" ... Ideally I'd like to have it here by the weekend if possible.

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Post by bmxguitarsbmx »

Interesting stuff Bajaman.

It would be interesting if the BAV99 was in fact a transistor. I don't get squeeling with 4x1n4148's however.

Someone with the original pedal could prove if my 1.4 drawings presence is correct: By setting the internal gain pot to minimum, presence circuitry would be defeated how I have it drawn.

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Post by bugg »

I have an original incoming. Should be here by the weekend. :thumbsup

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Post by destro »

https://postimg.org/image/bvdem87cd/

In this pic there appears to be a trace between r18 and c14, making the proposed 1.4 schem inaccurate. Interested to hear the diode/transistor tests.
Attachments
R18 C14 connection Friedman BE-OD
R18 C14 connection Friedman BE-OD

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Post by toneman »

the ZXTP25015DFH is a switching transistor, used for driving a power mosfet. Even has a complimentary PNP for totem pole configuration.
these transistors are not designed to operate in the linear region, only in the saturated or cutoff regions. All on/All off.
i would think that would make them, in a way, like a schottky diode in that they are used for highspeed/highfrequency switching.
but, highspeed switching refers to frequencies wayyy beyond----> audio :shock:
destro:
i dont even see a "C14"; i do see a "R18" :scratch: unless...... u've seen the "other side" :lol:
bugg:
didnt notice the "waiting time" :slap:
hey, soon U will know "the rest of the story" :thumbsup

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all i have are sneeze(s). [allergies]
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Post by bajaman »

okay folks - the continuing saga of "those" clippers :wink:
I finally tracked down a spice model of the ZXTP25015DFH SOT23 pnp medium power transistor, which i believe to be the ones used in the friedman be-od pedal :wink:
The clipping response when running the simulation with these sot23 devices is a lot flatter across the band between 100hz and 10khz and, a similar gain level is shown compared to the through hole ZTX951 devices I simulated previously. The ZTX951 simulations show a gradual and broad -3db dip in the response centred around 2khz but the sot23 devices are nice and flat - would be interesting to switch between the two types for slightly differing response characteristics perhaps :)
After simul-testing numerous pnp through hole transistors in an attempt to match the response of the ZXTP25015DFH devices the closest i could come up with both happened to be 4A devices.
They are the MJE253 (the closest match within a db) and the MJE15029 which has ever so slightly more presence. I also tried the MJE15031 and MJE15033 (higher voltage rated than the 15029) but these although good were not as close as the MJE253 and MJE15029 devices. I shall post some overall response curves soon.
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Post by bajaman »

graphs.gif
These graphs show the output frequency response characteristics using differing devices around IC2a gain stage.
In all cases the input signal level was exactly the same (10mv ), tight control set to minimum , gain at 15%, trim gain at 50%, treble and presence on full and bass at minimum, master output at 80%
cheers :)
bajaman
Did you use two transistors in each direction? How are they wired?
one pair of transistors, 2 pairs of 1N4148 and one pair of schottky and leds - transistors are treated like diodes - only base and emitter junctions used - no connection to collector pins.
the base of device 1 is connected to the emitter of device 2 and the emitter of device 2 is connected to the base of device 1 - just like two diodes reversed in parallel :wink:
Hope that makes sense :?
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Post by bancika »

Thanks, great info. And you left LEDs at 2nd and 4th stage unchanged for all sims?
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Post by bajaman »

Thanks, great info. And you left LEDs at 2nd and 4th stage unchanged for all sims?
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Post by rmroza »

"Do you have the layout showing the components numbers and values? The schematic just shows the value and the board just shows the component number."

"Yeh, having part numbers associated with values would be a BIG help in communicating any mods/improvements!"

Yes, this was another thing besides component numbers between schematics were different, then one or te other not called out, so you had to go back and forth and to confirm design.

ZTX951 Datasheet - https://www.diodes.com/assets/Datasheets/ZTX951.pdf

"On the face of things, these ZTX951 or similar devices are crucial to nailing the response characteristic of this pedal - diode clippers will NOT work properly"

"My ZTX951 transistors arrive from http://www.rs-components.com today - looking forward to fitting them and will advise results."

Cool. Appreciate your support banjamin as well as Buggs and everyone, so do NOT get us wrong in the aggregate and NO even if the board don't turn out to be the fine, I personally will not be wanting a replacement or any money back! I will order the new one and appreciate the effort you and everyone put in! :)

What we're trying to do is confirm design....baseline, then improvements and ALIGN each other since this was a very exciting project and everyone got engaged.

For the PNP transistors, do we just remove a leg, like collector and use base and emmiter in place of a diode??

Also, realize guys that again we have 2 things....baseline and improvements. MAYBE the 1N4148's are better than the original design?!?? Maybe not. I can tell you again, I have the original and althouth really good, I have some reservations. The tone I got out of this colective project (although noise I cannot get rid of), I have not A-B'ed (due again to noise), but sounds BETTER on the face value and again witout A-Bing!

"someone who has the pedal should use a multimeter and measure for accurate schematic layout at the very least before anybody tries to build this pedal"

What specifically do you need measured or everything? I have the pedal. I'm open to measure it or any way else I can help!

"I have an original incoming. Should be here by the weekend."
Ok. I was going to ask if you want me to send you mine!

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Post by bugg »

Once I have the original in hand I will remove the pots, take photos of both sides of the board, retrace the entire circuit, then remove one of the diode/transistors in question and determine what we're dealing with.

I'll leave the pedal dissected until there's no more doubt so I can reverify any questionable connections along the way.

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Post by albru80 »

Great job guys!
Your forum contributions to DIY are incredible!
Now I would like to ask something to rmroza:
You expect other people to give you fully working schematic and layout straight away.
You mentioned that you are an engineer and your time is soooooo valuable (I am an engineer and my time is valuable too, like everyone else).
May I ask: apart from constantly complaining, stating the obvious or keep repeating that you wanted to A-B the circuit with your original (which you don't have), what was you real contribution to this thread? Shouldn't you be more humble, appreciative and respectful?
I apologize if I'm wrong.

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Post by ozzy666 »

rmroza,

out of sheer curiosity, why did you not open up your pedal and take pictures or perhaps retrace the board by yourself that way bugg would not have to purchase his own?

bugg, bajaman

hats off to your contribution to the diy here! it's amazing!

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Post by bajaman »

why did you not open up your pedal and take pictures or perhaps retrace the board by yourself
yes - i was wondering that as well :wink:
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Post by bugg »

ozzy666 wrote:out of sheer curiosity, why did you not open up your pedal and take pictures or perhaps retrace the board by yourself that way bugg would not have to purchase his own?
We've come to the point where I really just wanted to see the thing for myself. I didn't want to borrow one because I don't need the stress of worrying about damaging someone elses pedal. If I break it, tough shit, my loss. :D

I sold PCBs to folks so I feel some level of responsibility to confirm the circuit is correct, I have no problem getting my hands dirty. You guys helped pay for it, so it only seemed fair. I'm not trying to get rich, let's put the money back into the cause. Once I'm done I'll sell it and put the cash into another trace. In fact, I already have something else on the way. :mrgreen:

BTW: ETA on the pedal is Friday.

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Post by rmroza »

Buggs, you are top notch!!!

"As far as "rmroza, out of sheer curiosity, why did you not open up your pedal and take pictures or perhaps retrace the board by yourself that way bugg would not have to purchase his own?""

I DID take mine apart and take photos...I thought posted! (thread is sooo long maybe buried or not). As was communicated on and Guitar FX page for the vero seemed confirmed, I didn't see the need of going the next step and depopulating the board or sending to say Buggs, but WOULD HAVE and as I said, soo many chiefs, I wasn't sure who was leading! You have Benjamin, and Alex, and Buggs, and Weedman, and....... It was not clear to me!

Buggs is taking the lead and we'll know 100% in a couple days, so let's just fall back and wait the feedback. If need be, mine is still available, unmolestered at this point and again, just waiting the FSB board and A-B things! Looking forward to it...as many many folk are. Thanks again all for everyone's support! :)

I again just ask a standard format and to reverse and clone 100% and not because certain components are common and readily available. Then move from baseline and improvement ideas. Maybe the common will be a better sound. Maybe not. Benjamin ran some analysis and suggested some direct cross reference parts...but again, just because in analysis or data sheet it looks better or is an ideal cross reference, doesn't mean it "sounds" better. Only your ears can do that versus theory.

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Post by bajaman »

who the fuck is this Benjamin character :?: :slap:
rmroza ? You could have saved everybody a LOT of trouble by accurately tracing this pedal - instead you only did a piecemeal analysis and made numerous mistakes - thank Christ or Allah etc that buggs has bitten the bullet and decided to accurately trace this pedal for all of us here - I have ordered one of his boards and cannot see any difficulty in modifying it if necessary, once he has done his analysis, which I am sure will be 100% accurate unlike your mess - and all the time this thread has run it's 15 pages you have been sitting on the sidelines sniping when all you needed was to open the fucking pedal up and measure track continuity with an ohmmeter ffs :roll: :roll: :roll:
Thanks but no thanks for your effort :blackeye . Crikey, you couldn't even get my username correct :roll:
bajaman (not benjamin :lol: )
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Post by bajaman »

Please ignore my last post - having a senior moment - frustrating pedal :lol:
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Post by bugg »

Now look what you've gone and done, you've made Benjamin blow a gasket. :mrgreen:

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Post by bajaman »

bugg - The more I try and figure this out the more I realise that your schematic is correct except for those smd clipping devices - i did a search for the BAV99 which someone mentioned were the correct diodes but the Vishay datasheet gives JE for the type marking so surely they cannot be correct.
The Zetex datasheet for the ZXTP25015DFH on the other hand gives 1A7 for the type marking, which is the same as the board pictures.
Using diodes for clippers accentuates the upper midrange compared to the pnp transistors which would tend to make it a bit more fizzy sounding perhaps :hmmm:
Still waiting on the transistors to arrive so will just have to be a bit more patient.
cheers
bajaman
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