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Messages - edvard

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Preamps and Effects / Re: Strange pedal issue
« on: November 10, 2018, 11:56:49 PM »
Yes the plug that won't work is TRS and it's the same with my other pedals. Explain?

Sent from my SM-G935F using Tapatalk

In a lot of pedals, the input is a stereo jack that has the (-) lead from the battery or adapter on the R lug, so that when you plug in a TS, it shorts to ground and you have power.  Your cable's TRS end obviously doesn't have any wire connected to the R lug, so the power never makes contact in the pedal.  Sounds like the cable is a home-build?  If so, simply open up the TRS plug and solder a wire from R to S.

I fried a Crate Mini-stack yeeeeeeeeaaaaaaars ago by accidentally plugging the speaker outs into each other.  Smoke smell and buzz were the result.  I'll hazard a guess that it's the same thing here.  If you open it up, you'll most likely find a chip-amp handling the speaker output, and the smoke will have escaped.  First thing I'd do is replace the chipamp and the output capacitor, then work backwards from there if that doesn't cure it.  I couldn't find any schematics or specs to suss out what variety of chipamp is loaded in there, but talk around the 'net says contact Crate and they can advise you on that detail.

Are you handy with tools and a soldering iron?

Amplifier Discussion / Re: parts
« on: July 18, 2018, 05:18:19 AM »
Let me rephrase that
Please teach me how to figure out a replacement part.
Do I look at data sheets?

quick google someone said 2n5457 - so I guess I need to compare data sheets on those.

The 2SK30 is an N-channel MOSFET, not a JFET like the 2N5457.

I would go to, do a search for N-Channel MOSFET and plug in all the details you can from the 2SK30 datasheet in their search filter.

As far as suppliers, I tend to order a lot of parts from Tayda Electronics, but I've used Futurlec and Mouser a few times as well.
Tayda keeps up on what's in stock and available, and their shipping is reasonable.  Futurlec can have stuff you won't find anywhere else, but there are complaints all over the net about their shipping time, mostly because they will hold up your entire order for one item that's out of stock.

Tayda says 2SK30 are out of stock, Futurlec says they have them in stock, but don't believe them until you get a positive response.  Their "Contact us" page has phone numbers and email addresses.

Amplifier Discussion / Re: Thinking about building a SS amp
« on: June 17, 2018, 03:57:20 PM »
As to tone controls, be aware that "Tone mender" has a noise penalty but then most passive tone circuits do come with the old *Insertion loss* and as they are Hi Z they tend to pickup noise if your design and layout is a bit sloppy.

I spent many years bread boarding and building tone control circuits and the one that impressed me most was the HiWatt circuit. <3)

The most frustrating part was learning how to circumvent the noise problems. I doubt one will ever win the S/N battle but my PhAbbtone circuit is very quite when compared to Tonemender.

This will certainly work and (unlike fender and similar) has a midrange control that actually WORKS. ;)
This gives a big round bass as well as bright treble,, May even be too bright for your liking but you mentioned adding a top cut which is a good idea,, I just use a cab sim which has similar effect.
I've recently run across your PhAbbtone circuit, and will be the next thing I test.  A usable midrange would be nice, though I've found a flat midrange is enough.  I haven't noticed much issue with noise in the ToneMender circuit, but then again, maybe I'm just used to it :P
What impressed me about the ToneMender (with my subtle tweaks) is that when I cranked a knob, I FELT it.  Most generic FMV and the Baxandall circuits I tested were way too subtle, and the ToneMender even had usable tones at extremes of the knob positions, which I found amusing.  Hopefully, I can give a good report on the PhAbbtone...

The other circuit that impresses me is a simple compressor that a FSB
member *mictester* designed and posted.
Original post here BUT you will have to be a member to read it.
I've seen that one as well.  I like the simplicity.  I've thought about having a compressor/limiter on the end of the chain just before the power amp just to keep things tame going into the watt generator, but that might not work as well as I think.  I prefer a comp at the beginning of the chain, and even then mostly for clean stuff.  Come to think of it, maybe a good compressor circuit might work well as a second channel if I decide to make this a channel-switching amp.  Not that I do much clean playing...  8|

If any interest I can post my Cab sim circuit as well?
By all means.  That might make a good dedicated-out for headphone practice or in situations where I don't have access to a computer to play cab simulator (Yes, I know...).  Most cab sim circuits I've tried range from "is this thing on?" to "Good lord, what speaker is THAT supposed to be?".  Hopefully yours is different.

Regarding Power Amp design.
In My limited experience (hey it's only a hobby for me)
I've researched and tested Current FB setups on SS power amps and although it does alter the outcome it's a not mind blowing difference.
I've played a few SS peavey amps with Sat control (I think that is what it's called) and it does alter the outcome a bit but I suspect that a SS power stage running an output transformer might reap far better results.  but that bumps up the cost :-\
At high volume CFB seems to help but for home use it may not be audible.
I have a massive Factory type PA amp which has 70/100 volt output transformer as well as an 8 Ohm tap which does a good job of replicating a cranked Valve power stage but same limitation, you don't notice it at low volume.
Thank you for your insight on that.  When I first ran across the CFB idea, it simply made sense to me, even though I suspected it wasn't a huge difference in the sound (or else we'd ALL have CFB amplifiers in our home and car stereos).  That and Rod Elliott mentioned that CFB might add a little margin of safety for the speakers (emphasis on 'might' and 'little' :P).  I also have one of those 70 volt PA distribution transformers, which I bought a loooooooong time ago in anticipation of building a low-wattage tube amp.  Maybe I'll save that one for the eventual MOSFET experiments...

Oh yes,,good looking job on that guitar. :dbtu: :dbtu:
Thanks, I haven't been able to put it down since I built it, which makes things a bit inconvenient when I think about doing a few details like shielding the cavities, taming a few wily fret levels, or tweaking the tone control.  I've also noticed it really does need a belly cut.  Age and a wife who's an amazing kitchenista has not bode well for my midsection.  ;)

here´s some of the new stuff, which I introduced at the 2018 Convention of the Audio Engineering Society Buenos Aires branch:
Holy smokes JM, those are some fancy lookin' amplificators.   :dbtu: :dbtu:

As usual, I have a mildly heretical viewpoint.   :)
I remember you from the stompbox forums.  Your viewpoints have always been helpful, heresy or no  8|

Chip amps do have fundamental limitations on their ability to dissipate power. As a practical matter, the TO-220 packages like the LM1875 can only really do a 20W amp out at the edge of reliability. The LM3886 and similar packages can get to about twice that and be reliable without gigantic heat sinks.

My solution to this is to use the LM3886, which is an incredible deal at about US$5 each, and use more of them. There are circuits to parallel them up for higher currents and better power dissipation, and to run them bridged for higher voltage. However, I would not use them that way.

The LM3886 is quite reliable (given a decent heatsink) at 30-40W output. Most guitar amps run one 12" speaker on about 30-50W of amplifier power. When it gets over that most amps run two 12s or four 12s. Why fight the 30W per speaker practice? Why not make one highish quality amplifier per speaker. They're easier and more reliable that way, as well as more adaptable to situations and portability.

I just went through this in designing a replacement/repair power amp for the Thomas Vox amps. I opted for using an LM3886 per 30W speaker load. This covers the Buckingham and Viscount with 8 ohm loads with one amp each. The Royal Guardsman needs two modules to run two 12s at 60W, and the Beatle needs four for 120W.

It is far easier to get a 30W amp to run right than to get a 120W or higher to run right. And replicating several small things can be simpler than making one big one.

I did a PCB that is about 2" by 3" and runs one LM3886. I found a suitable heat sink for under $8 at Antek offers the AS-0522 toroidal transformer for $17.50, and this is a nearly ideal transformer to power the LM3886. You can fit the whole amplifier on one heatsink serving as a sub-chassis, power supply included.

And if one fails, you've thoughfully made one more power amp module than you really needed, so you swap in the spare while you fix the broken one.

Just sayin' ...
Thank you for the insight.  My current intention is to refill the unfortunate carcass of a late-80s Crate 'mini-stack' with my own design stuffed in the head and replacing the two 4x6" speaker arrangements with one 12" per cab.  Using one chipamp per speaker would fulfill my wattage desires, and have a little more beef than what was originally there (two TDA2030s, one for each speaker, running at 10 watts each).  Making these higher-powered chips run a little cooler would save me on power supply and heat sink costs.  Glad I wasn't the only one thinking on those lines. 
I'm really only intending to use the chipamps to get the thing making noise, and go discrete or MOSFET later.  I might even dip my toe in the Class D water someday, but today is not that day.

Amplifier Discussion / Re: Thinking about building a SS amp
« on: June 17, 2018, 06:42:40 AM »
Thanks for the insight JM.  I knew the 2050s had gone out of production, but I didn't know it was that recent.  If I'd been paying attention, I would have snapped up some myself.  Either way, such is the fate of specialized devices, which is why I'm debating making this thing modular at the least.  I'll most likely build a proper discrete power section at some point, I'm leaning toward MOSFETs, but not sure if that's the best choice.
Until then I got these chipamps to make noise with, and that's what counts.

Back to the bench!...

Amplifier Discussion / Re: Thinking about building a SS amp
« on: June 17, 2018, 03:13:16 AM »
I like the guitar project. I also took inspiration from Ovation electrics using the Viper body shape.

Those Vipers are pretty sweet, minus the pickguard; never liked those bubbly pickguards on the Viper or the Preacher, though I admit if I could own one of each, I probably would...

On to tone controls.
I've tested a few different takes on the Baxandall and the classic FMV tone stacks in my breadboarded preamp, and the one that ended up staying the longest is a slightly tweaked version of RunOffGroove's "Tonemender".  I wanted to like the Bax, I really did, but it's just too subtle for the duties I have in mind.  However, I've noticed a bit of high-end unpleasantness on higher gain settings of my preamp-currently-under-test, and now I'm wondering if there's something different that might work a bit better...
I'm thinking two gyrators for Bass and Mid, and a cut-only Treble.  The Bass control will be a 'shelving' control that cuts and boosts.  The Mid control will be centered at ~650 hz that only goes flat or notch. I may make it adjustable from ~350 to ~1200 hz because it's just only one more potentiometer, though I'm kinda questioning the usefulness.  Lastly, a cut-only Treble because the last thing most folks need is shriller highs from most amp topologies (mine included) that tend to end up on the sharp side of the spectrum just before tone controls anyway.
Thoughts?  Opinions?

Tubes and Hybrids / Re: What to do with this old Pye radio?
« on: June 14, 2018, 01:48:30 AM »
If the capacitors have paper sleeves, a good trick to upgrading but keeping the "vintage" look is to put new caps in the old paper sleeves.  Done correctly, nobody will tell the difference.

I was unashamedly asking for *opinion* on heads you may have used that you like the sound of or conversely do not like.

My apologies, but I plead the hive-mind of the internet.  Ask opinions on a ham sandwich and by the second page it's a full-blown smackdown on whether French Crullers are better than Danishes.

What kind of music do you play?  I am assuming something Rock-oriented but I don't like to assume.  If you lean towards the harder side, I don't think you can go too wrong with a Randall RG series.  I can personally vouch for pretty much any Peavey heads for clean tone, and some TransTube heads have switchable loads. Beyond that, not sure.

Amplifier Discussion / Re: Thinking about building a SS amp
« on: June 11, 2018, 02:36:26 PM »
Hey Ed,,
Those TDA2050's are a 28Watts @ 4Ohms Watt chip,,Depending on load and PSU. 35Watts if you want to push 4 Ohms with 10% Distortion.
The 50Watt crap is music power which is a fancy fan-dangled way of making it look more powerful. That is what happens when marketing geeks use maths. :duh
Back at a less stressful 8 Ohms and it's somewhere between 18 ~22Watts RMS in the real world.
So I'd call that what it actually is,, about 20Watt Chip.

Yep, I know the marketing-speak and I got the 35 watts at ±30V from the Volts-to-Power chart on the datasheet.  I know they are simple-but-tough little critters and you can push them to get better power, and bridging them is even funner, but I'm trying to keep it simple.  For the moment they are out of stock at Tayda, so I won't be trying them anytime soon.

Frankly you sound like you are over thinking this whole thing. 8|

HA! Ya think?  :dbtu:

A SS power amp of any type normally used is a world away from a Valve equivalent. The rare circuits that might be able to compete will cost $$$.

I stated in my first post I'm not trying to concoct a magic equivalent of tube amps, and I think that's a lost cause anyway, for reasons I am not interested in discussing.  Seems to me, the only things truly in common between tubes and silicon is they are both made from hot glass and they can both amplify.  After that, there's a lot of dead horses being beaten, and I want no part of that.

With SS all your tricks are easier and a lot $$Cheaper$$ to do in the preamp.

Pre-zactly.  The one thing I do like about tube amps is their innate habit of soft-clipping even when running clean, and that mostly holds for the pre-amp triodes.  Output pentodes can clip just as ugly as their 3-legged cousins.  Well, so can triodes if you abuse bias them properly, but I digress.  My pre-amp tricks aren't new, but hopefully pleasant as I try and avoid hard-clipping (I may say more about that later).

That TDA7294 is likely the best bet and just follow the data sheets.
Though LM3886 has less pins and likely a bit easier to make a PCB.

Chip amps can run just fine for years if used as intended.
i.e. a proper heat sink and conservative loads.

I got those because they were dead cheap, and my favorite supplier is currently out of stock of 3886s. I will probably pick up a few at some point, just trying to avoid fakes.

I've built a few discrete pwr amps like ESP's P3A and they run fine. About as simple as it ever gets 8|. They have no Short protection and as Rod states in one of his pages the current protect circuits are not fool proof anyway and can fail.
So I just use a PTC on the output as they negate all the extra current protect circuitry which makes life easier for a home builder.  These are poly thermal switches and are sold as speaker protection devices BUT they can also protect the amp from shorts IF inserted right at the output of the power amp pcb. :dbtu:
They look like a disc cap.

I've built about a dozen amps using these for protection and had no trouble. <3)

I guess it's kinda silly of me to complain about the complexity when I've built more than one Big Muff  :loco , but I can't help but get just a little freaked out looking at those glorious schematics.  I'll probably opt for Project 27 if/when I decide to do a discrete power section, and I am intrigued by the whole "current drive" thing anyway.  Thanks for the PTC suggestion, I'd wondered about that myself.  I've got a good handful of them in my parts buckets...

Back to preamps,, Go purchase a bread board or 2 and start experimenting with a few simple preamp circuits.
I have a few circuits on here which are simple but quite effective, some are on my pedal board some tricks are in amps I have built.

My pedal chain is a fet preamp>> a couple of dirt pedals (never maxed out)>> mictesters (from FSB) compressor circuit (Brilliant) >> my own cab sim design>> my not Famous but very potent PhAbbtone and the amp is actually an old Laney keyboard amp. I have owned and built many amps, Valves as well and the above line up is still my go to rig. It just works.  <3)
I can plug my acoustic into this,, I can use my Strat and when needed I plug in keyboards as well.
I can pull country clean,, to ZZtop thick OD with ease.

As much as I always wanted to have  all this in one Amp I've had revert to pedals as it's just more versatile.
Most of my circuit schematics are on this site.
If it interests you I'll take some pictures?
Hope it helps ,, Regards.. Phil.

I've got more breadboards than I can shake a stick at, so I'm good there.  Being a former pedal junkie, I got pre-amps pretty much covered, though if you have links to some of your favorites, I'm always interested, thanks.
I'm focusing on the power section at the moment because I know I can whip up a pre-amp practically in my sleep, and power has always been an afterthought; the job of whatever amplifier I'm unhappy with at the moment.  It's a challenge and I want to learn.
In fact, that's the whole point of this experiment, to make a standalone amp that I'm happy with because I put all my best ideas in one package.  Yes, a chain of pedals can be quite versatile, but if I wanted to fiddle with pedals, I would have kept the old Peavey I sold because I hated the distortion channel.  I want the simplicity of just plugging in and cranking up without having to worry if my batteries are fresh.  I built my own guitar because for the same reasons; I have two others that work just fine, but now that I've built one, it's my favorite, and I'm going to build another based on what I learned with the first one.

Yeah, I'm overthinking it, and I probably can't compete with what the "big guys" have already done and been doing for the last 50 years, but dangit, I'm having FUN...

P.S. My guitar project, if you're interested:

Amplifier Discussion / Re: Thinking about building a SS amp
« on: June 11, 2018, 04:44:00 AM »
I've heard of Sloane's book, but haven't picked up a copy yet.  I've also amassed a large collection of datasheets for TI and other chipamps, as well as many Application Notes from TI, National Semi and others.  I've also pored over collections of schematics and have built quite a few stompboxes, so I'm not exactly new to the subject, I just have never before assembled the required parts into a cohesive unit, AKA a solid-state amplifier that is tweaked to MY tastes and preferences.

My first hurdle is going to be power, as in how am I to feed current into this collection of parts.  That means starting with the power amp.  In that regard, we have a few choices:
Pros: Simple to design for, and can be inexpensive if you shop around.
Cons: Many good chips are now obsolete, and current production will someday be obsolete as well.  Not sure I want to chase that dragon, so if I settle on one, I should probably buy 3 or 4 more as backups. Or perhaps make the power section a separate module, so I can simply replace it with whatever the cool kids are using that month.
Pros: LOTS of designs freely available on the web to suit many tastes and power output needs.
Cons: Can be complex, which can lead to expensive, depending on what bells and whistles you want.  Speaker protection? Power-on muting? Even more complexity.
Pros: Most common circuits are less complex than Discrete designs overall. 
Cons: Lateral MOSFETs (that means the GOOD kind) are designed for audio, and are VERY rare/expensive.  Cheaper vertical MOSFETs are not designed for audio, so they can be more "touchy" to work with, but see International Rectifier's Application Note AN-948 "Linear Power Amplifier Using Complementary HEXFET Power MOSFETs".  Very informative.  Also, heat... so much heat.
-Class D
Pros: Same pros as chipamps, but with vastly reduced heat concerns.
Cons: REALLY not targeted to guitar, and need to be protected from transient input spikes.  Overdriving a Class D chip is not pleasant.  At all.

I happen to have a few different chipamps, so I'll roll with that for this first project.  For the TDA7294 I have, ±30V should give me ~50 watts.  The Triad Magnetics F8-24 should get me there, is within budget, and has a 100VA rating, which Rod Elliott might argue is a bit under-powered for a 50-watt guitar amp, but anything more than that gets spendy pretty quick.  Besides, I don't plan on gigging with it any time soon; I'm not THAT good...  Alternatively, if I can find a good source of TDA2050s, I suppose I could live with the 35 watts it can put out with a ±18V supply and a 4-ohm speaker load.

Two thoughts:
Can the cab not be re-wired for a lower load?  From pictures I was able to look up, the speakers are 16 ohms each, wired series/parallel.  If you wired it all parallel, it would come down to 4 ohms.

See illustrations below.

While that would bring the overall load down to something more useful, it won't magically transform the individual speakers into 4-ohm units, so the frequency response will likely be somewhat different from a standard 1960 cab.
I realize that would also limit your choices to amplifiers that are capable of handling a 4-ohm load, but as JM stated, that's at least more common.

Second thought:
While a 16-ohm load would reduce the power available from a solid-state head, isn't that what you want?
while I love a plexi as much as the next guy, I'll need a decent reactive load to keep the peace with the neighbours if I want to get the right crunch out of one - not to mention I like having my hearing.
Though I agree with JM's opinion,
"too much cabinet for too little driving power".
it might still work for your purposes.

I would NOT plug a 16-ohm cab into a tube amp that doesn't have a 16-ohm output.  There are all kinds of reasons why not that I won't get into here.  Suffice to say that it's not good for the output tubes or the output transformer to mis-match loads.  Solid-state is a little more tolerant, just with the afore-mentioned imposed power capability limitations.

Amplifier Discussion / Thinking about building a SS amp
« on: June 09, 2018, 04:27:10 PM »
Yep, just the thinking part for now, though I already have most of it worked out.

Here are my first thoughts:
1 - Start with the speaker and power section.  I get the nagging feeling that designing a SS amp is akin to pairing up a distortion box with a 3-band EQ and power amp, so we start with the limitations (power watts and budget) and work down from there.  I'm thinking 50 watts is a good compromise between "I might have to gig with it someday" and cranking it up to a dull roar while the wife is out shopping.  I want the best speaker I can afford that doesn't have "British Voicing" (to my ears that means "sounds like a box"... sorry, that's just me).  I am also torn on the issue of the power section; basically I have 3 choices: Discrete, Chip amp, and MOSFET.  They all have their pros and cons, but that's for further discussion...

2 - Single channel.  In the '80s I cared about channel switching.  These days, I don't need to go back and forth; I have re-discovered my guitar's volume control so I can go from "Really Crunchy" to "Not So Crunchy" without having to set up two different tones. 
However, just writing this paragraph is making me think I may change my mind.  More about this later...

3 - Don't try too hard to emulate tubes, except for soft limiting in all clean gain stages.  An elegantly designed overdrive stage doesn't do much good if your signal hits the rails before it even gets there.

Thoughts?  Opinions?  I've read a good part of TeemuK's excellent book, so that's given me some good groundwork.  I'll lay out details in following posts, and give a complete schematic at the end for any other intrepid solder junkies.

The Newcomer's Forum / Re: Hello from the new guy
« on: June 09, 2018, 03:47:18 PM »
The Crate board was cannibalized for pedal parts years ago.  I was never 100% happy with the preamp anyway; I had to crank up both volume and gain to get a decent sound out of it.  At one point, I had audacious plans to house a tube amp in the head, but those plans never panned out (power transformers are spendy!), and I'm not in the mood to deal with tubes these days anyway.  The amp was rated for 20 watts output (2 TDA2030s at ±12 volts to make ~10 watts each), so the original transformer will have to go to something else.

The Newcomer's Forum / Re: Hello from the new guy
« on: June 07, 2018, 10:50:55 PM »
Well tel us what those other Amps are that you have laying around because you may find you already have got most of what you need. :tu:
They may only need small mods to better suit your needs.
And maybe add a link to schematics of same if you can.

Amps I own at the moment:
-My grandfather's 1952 Fender Deluxe 5A3, which is a great tube amp, but it doesn't do the Rock thing so well, and I'm a metalhead from way back.  It's amazing how much this thing doesn't distort.
-Park Bass GB 25-12. It's a bass amp, no more, no less, and doesn't distort either.  Currently doing duty as the speaker for my science experiments.  More about that later...
-First Act MA214.  Small practice bass amp that came with the bass my wife got me for Father's day a few years back.  It sounds OK with guitar, as long as you've got a good dirt box in front of it, and even then it's just OK.

For my current plans, I've got the cabs and head of a Crate G200C XL "Mini-stack" that I bought new in '89 and gutted YEARS ago after the power section blew, and I couldn't find the chips for it.  This was back before the internet could have gotten me 2 TDA2030s to fix it for less than bus fare downtown.  The cabs are loaded with four 6"s each and they sound awful; imagine shaking a sackful of marbles and that's what distortion sounds like through these cabs.  My current goal with that is to replace the arrays of 6s with one 12" each for true girth.  I need to find ones that will do OK in smaller-than-average sealed cabs though.

Also if you want an easy 50 Watt power amplifier then look at the LM3886 power chip, there are many circuits and PCB's on the net for that chip.

Yep, I've looked at that one many times but could never afford it, and I had the hots for some TDA2050s before they went out of production.  At the moment, I've managed to snap up a couple LM1875s and a TDA7294 with some Christmas money, so I'm not out of options.

I'm thinking I've finally got my thoughts straight on what I'm going to do with all this silicon and hubris; I'll post in the relevant section later. 

The Newcomer's Forum / Re: Hello from the new guy
« on: June 04, 2018, 02:34:47 AM »
Hadn't thought of that, thanks.  I've also found a guy on eBay who sells old speakers pulled from organ units and the like.  Many of them look like re-branded Jensens and others, and many are dirt cheap.  I haven't seen any 'victim of an upgrade' speakers on my local Craigslist, but I'll keep looking...

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