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Darker Sounding Preamp?

Started by exztinct01, November 17, 2016, 10:53:59 AM

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exztinct01

I've been using my P27 preamp with a silicon fuzz face clone in front and is not quite satisfied with the results. I love the cleans of the P27 alone, although not amazed by the sound produced by those clipping diodes. I might just remove those in the future.
However, I also want some darker sounds for other kinds of music. What preamp can I build to achieve this?
My speaker only adds to the brightness of the P27 and adding that FF clone resulted in harsh and unpleasant sound IMO. I need some dark distorted sounds from some gears, be it a complete preamp, a distortion pedal, that will balance the brightness of my speaker.

PS: I was considering the Lead 12 Pre as it already earned some praise from people more experienced than me but I don't know if it's what I need. Is it?
~ Stephen

exztinct01

Additional Info: I use a Telecaster copy so setup's really bright. I just have to ask if it can be achieved  :loco
~ Stephen

J M Fahey

Dark and Tele do not belong in the same phrase ;)

That said, you omit a most important information: what speaker are you using?

Besides that, "Fuzz-anything" IS a recipe for buzzy sound, if you want a darker distortion, a RAT with its cut only, variable frequency tone control can go from dark to mud.

Build one, it´s actually quite simple, and the project, including an iron on transfer PCB dsign is available at the usual pedal sites.

Don´t sweat to get the original LM308 Op Amp, which has been obsolete by decades, use either a TL071 for a slightly brighter sound to a 741 for an old, Lo Fi sound.

LM308 needs an external compensation capacitor, which you´ll see in the original schematic; not needed in the "modern" ones.

The Marshall Lead 12 is killer sounding, but (as expected) , quite aggressive; I guess your problem mainly lies in the speaker and somewhat less on the guitar.
Using thick strings ( .012) will help a lot.

exztinct01

I've been using eminence red white & blues, which i know is not really for that kind of sound i am looking for. I was just wondering if something can be done to enable my setup to get darker  :)
i can't change my guitar and speaker, but maybe the electronics will get me there? some eq maybe?
~ Stephen

exztinct01

i just realized I'm asking for varied sounds using a Tele and an RWB, and many times I've read that versatility can only be achieved by using multifx rather than single amp, is this necessarily true?
~ Stephen

J M Fahey

Build and use a 6 band or more graphic EQ (one of Phatt´s secret weapons  ;) ) and insert it between preamp and power amp.

No need to use slider pots, which are the home builder´s nightmare, but conventional rotary ones, which are easier to mount.

exztinct01

~ Stephen

phatt

#7
From fig 1 of P27 preamp.

Try doubling the value of C9 (120p). You can do the same for C4 but do them one at a time as you may only need to do it on U1B.  Raise the value of C8 if you want more bottom end.
You might also try a ~ 470pF cap across the input at U1B,, I'd have to simulate it to be sure but then your speakers might be very different to mine so suck it and see what happens.
Yes the diodes are likely going to be disappointing,,  I'd just delete them and use pedals for dirt.

FWIW,,,In my humble hobby experience home builders of SS amps are better off just building a one channel clean SS unit and use pedals for all the fancy stuff.

I'm yet to find a player who has purchased a 2 or more channel hot rod Brand name rig with built in OD/ Crunch/ Dirt/ Distortion amplifier and was happy with it all.

Most common answer is; I ended up only using the clean and rely on pedals for the other stuff. :loco

Now if the Big names struggle to get it right what chance does the novice have????? 8|

I just scored a SState Fender Bassman 200 for a mate.
Probably not the best Bass rig but with just One channel it does have a couple of important features which are rare. My mate does a lot of acoustic playing and his Peavey Bandit is far from ideal as it really trashes his beautiful guitar playing.  :'(

He also owns a AER mini rig which is ok but being very small seriously lacks the fullness he needs, (cost him a small fortune) :o

I only had to plug  into the Bassman for a few minutes to realise that the simple controls on this Fender actually worked,, stunningly brilliant tone control for such a middle of the road quality Fender rig. :dbtu:
Next to it was a Fender FM 212 which was (as expected) just trashy cheap SS sound. yuk.
The Bassman has a tweak-able low freq roll-off as well as sweep mid control.
Combine that with a 15 inch speaker and a small horn which is controlled via an Lpad on back panel and it just works.
Limiter seems to work ok and compressor is noise free. but I doubt they will be needed for acoustic as the amp is not over powered.
Master works very well i.e. no big massive jumps in volume ,, just a steady increase. No Feedback problems at high levels so If I was about to build a preamp I'd seriously consider using that preamp as a template. :dbtu:

My strat and pedal board sound great through this Bassman as well,,, better than my Laney that's for sure,,,, Geez I wish I had the spare cash at the time. :'( :'( :'(

Nuff of me ranting,,,Now back to the problem.
Speaker might be an issue as Tele's are by nature very bright.
I recall reading an electronics article years back where the (obviously well versed writer) noted that it might be better to design a HiFi system from speaker back through to amplifier as the speaker is the defining factor. Having built a lot of stuff I tend to see the wisdom in his observations.

Most guitar players tend to buy an amp then spend forever swapping speakers to find the the sound,, A rather time consuming and costly exercise.
But then most players don't understand the hidden secrets of speakers and even a lot of experts could not tell you off the top of their heads which is best for your particular sound. Point being;; Mr Fahey builds his own speakers so  maybe start with his recommendations, might save a lot of frustrations. 8|

I've ranted enough.

Phil

exztinct01

May I add another question. If I remove those clipping diodes and the other related components, will it make the preamp's volume at max higher? I just thought that since it clips the signal, so the resulting volume is a bit lower.

~ Stephen

phatt

You may,,  ;)
Yes the output will be a bit higher but no clipping.
Just lift one end of both diode strings and that will disable it.
You can leave the following circuit intact. 

The diodes form a type of limiter circuit but I doubt most players would like the way it responds.
IF you wish to keep the limiter add a 1k~5k pot in series with R14 (220R) you will then be able to dial in the amount of limiting you need.

The Bassman 200 I mentioned uses a limiter that is very similar to ESP circuit.
The idea has been used in many circuits but will not sound very Valve like,, if that is what you are hoping for.

I use a very simple compressor for the overdrive effect of old valve amps and just use a fet boost which then enhances the drive effect of old Valve gear.

OR as J M Fahey has already noted,,, just build a RAT,, Hint. 8|

The beauty of using pedals with a basic SS rig is that you can build your sound from small external circuit blocks. Believe me it's a lot easier to do that than to build 10 or 20 Amplifiers in vain hope it will deliver. :duh

My Laney only has 3 knobs,, Gain Treble and Bass and a master volume.
On it's own it would be the last amplifier a guitar player would purchase but in combination with external pedals it delivers a lot of versatile usable sounds.

Hope it helps,, Phil.

exztinct01

#10
Quote from: phatt on November 21, 2016, 06:22:50 AM
Hope it helps,, Phil.
oh it helps a lot!  :)
Well then, the RAT will be next on my list.
Right now, I just finished the Lead 12 Preamp, Rebote 2.5 delay and TS 808, all on vero and all without a case. They're still on my bench waiting for their enclosures. I tested them all and they work except that I don't think I like the sound of the TS, it doesn't sound like a TS at all when I tested it in front of my P27 Pre. I'll try removing the clippers in the P27 and test the TS again in front.

Also, I'm planning to build the Multicab Simulator to be able to play direct to mixer/PA speakers or PC. Good idea or not?
We'll be having a big church event in an open field and we don't have any stacks that can handle that requirement. We do have an MG250dfx and it has done it before but it will be used for one guitar only, so we need to connect the other guitar to PA system, and upon reading, I realized we need a cab sim to reproduce guitar tones.

Edit: Not actually open field but an open plaza (think of two open basketball court size), surrounded by some small establishments and a park. Also, the MG250dfx did cut it but at almost max levels, we tried connecting it to PA but we know how harsh the sound of those early MG series are, after hearing the distortion in the PA system, the sound guy removed it immediately.
~ Stephen

phatt

The TS circuit tends to work well into Valve Amps where there is often already an Odriven signal and the freq response curves are also different than most SS circuits. A pedal which some famous player used through a big Valve rig will likely sound very different through the rig you have. It's a very common misconception that the *Pedal* delivers the tone but truth is,, it's a combination of many many factors and there are many ways to achieve the same result.  some simple some insanely expensive. :-X

So yes a cab sim might help but not always. The PA Rig will likely have at least a 2 way speaker system and direct line out even running through some cab sim circuit will still come out harsh and brittle because the PA system has *Full Bandwidth* speakers.  Easiest way is to mic your MG as that will remove a lot of the top end hash you often get from line out DI setups.
Expensive way is to use a second Amp or slave into a power amp into a big Quad box or similar setup.

I had a young fella asked me a simple (but intelligent) question a while back.
What in your opinion is the problem with modern amplifiers as the old ones always sound better?

My answer was direct and simple; TOO MUCH BANDWIDTH!!!!! :trouble :trouble :trouble
and that goes for both SS and Valves.

BTW Diodes Alone DO NOT alter the tone curves removing them won't change the tone much. They do tend to add a lot of high end hash with some SS. Valve Amps by design tend to roll excess hi freq and that goes a long way to exlplaining why a lot of SS rigs tend to sound harsh. The MG250 is a 50~60Watt @ 8 Ohm amplifier,, likely 2x12 speakers. So yes at larger venues you need to move more Air. I doubt a cab sim between the MG and PA will do much especially if the guy behind the Desk does not know the tricks.
 

Regarding Removing diodes, you will likely still need to wipe off some top end and then try the TS Circuit again. Depending on the speakers you run through it might work.

A lot of Modern guitar speakers can be extremely harsh when compared to older units.
I replaced the Fane Speaker in my Amplifier which was extreme with a lower SPL rated speaker and it made a world of difference.

Phil.

exztinct01

Thanks to all your answers. I had a friend bring his Epiphone LP, plugged it in my Lead 12 Pre assembled in a lunchbox  :lmao:, then to the LM3886 Power Amp, to my Eminence RWB,
and WOW, so different than my Tele to P27 Pre Setup. I won't say that I prefer this new setup, since I still like the clean tone of the P27, but for darker ones, I will go with the LP to Lead 12.
~ Stephen

J M Fahey

QuoteI don't think I like the sound of the TS, it doesn't sound like a TS at all when I tested it in front of my P27 Pre.
You mean a TS played by you into a P27 preamp into an LM3886 into a single 12" Eminence it does not sound like a TS used by SRV (the main factor) using his guitar and strings (did you try my suggestion of thick strings? he often used 0.12 sets  :o and some mentioned he went even higher) , into a Super Reverb played full blast and then some, or a Vibrolux, same thing ?

pedals are the MOST overrated element in the signal chain.

I was almost lynched at MEF because I said the Zendrive was quite similar to generic distortion pedals and I found no justification *at all*  for its fame as "a Dumble amplifier inside a pedal box" .

I was given a list of top tier Guitar players which used it, maybe I was not that impressed considering all of them plugged it into a *real*  Dumble amplifier .

A Blues playing friend of mine got pretty excited about a Boss made "Fender Bassman 59 in a box" pedal or the "Fender Deluxe ´65 in a box", which are expensive and hard to find in Argentina (basically because shops cater to the much more abbundant hairy metal community) , so he bugged everybody who travelled to USA to bring one for him.

Boy, WAS he dissappointed !!!!!!!!  :-\

- "Hey Juan, please check it, it sounds NOTHING like the YT videos !!!!!"
- "Did you notice that in all videos guys plugs into this pedal ... and then the pedal is plugged into a Fender Tube amplifier?"
8|

exztinct01

i haven't tried the thicker strings yet, can't find a store with it near my location
But I'll order online as soon as I have the $$  ;)

Anyway, I removed the R14 and the clippers in the P27 and replaced the R13 (4k7) with a 100 ohms one, I left the Master Volume and emitter follower circuit in there and I did not change the connection of the output. Is it okay or should I connect the output jack directly after R13 which would make the Master Volume useless?
~ Stephen