This gets a bit off topic from OTL amps, but in my opininon, there are quite many "unneccessary" tubes in a generic all-tube amp. Basically, you can evaluate how much each tube stage -really- contributes to overall tone and then just substitute the "transparent" ones with cheaper solid-state circuitry.
For example, input stage of a generic tube guitar amp has very high headroom and receives a very low-magnitude signal. Under practical conditions, including "boosting" the input signal, it's quite difficult to get any clipping distortion from the first gain stage. The harmonic distortion it introduces in linear region is basically inaudible too. You can easily substitute this with a solid-state circuit and no one hears a difference. In addition to things like FX loop buffers, reverb driving amps, active tone controls, etc. you'll likely also find one or two "recovery" gain stages from the signal path, which have no other purpose but enhancing SNR by amplifying a weak signal stronger (no clipping). All this can be substituted with solid-state stuff and no one will likely hear a difference.
In the end, you may notice that tube clipping distortion is acquired only in two or three stages of the preamp. Those are only tubes they "audibly" require to have. You can substitute rest with solid-state circuitry that is functionally similar. You may not be surprised that the result of this conversion ends up being like many todays "hybrid" amps that have just one or two dual triodes in the preamp section, but the important stages that contribute to clipping.
I don't know why it's such a trend to call them "gimmick" designs with token valves. Usually the tubes have specific function in these circuits, and it is to acquire specific overdrive characteristics we have got accustomed to. You typically find one of the following:
- Common cathode amp directly coupled to cathode follower, typically driving a tonestack (classic Marshall amp clipping circuit)
- Two capacitively coupled common cathode amps, (modern "cascaded gain" clipping circuit)
As is, these two have somewhat different clipping and bias shifting characteristics, very important contributers to "tube tone", and you'll find them being clipping circuits of many revered tube-based guitar preamps. I don't know where the "gimmick" label comes from.
Ok, I do know a few designs of that nature too...
But tubes are just glass bulbs to me. I can relate to all non-related topics like visual aesthetics, nostalgia, etc. - some of it definitely even affects how we hear psychoacoustically - but for audio/electric purpose that glass bulb is just a "black box": It has certain function, we can analyze its behaviour, we can substitute it with a circuit that performs similarly, at least according to our personal expectations and preferences about it. Personally, I feel it's just a minor step further to analyze characteristics of those tube gain stages and mimick them with solid-state circuitry. But that's a different story. But if you ask is there stuff we can "remove" from valve amps then yes, there is plenty of stuff in all-tube amps, which could be converted solid-state without affecting the operation audibly or without loosing that tube-associated "feel" of interaction with the amplifier.
Preamps are usually way less complex than power amps: Current draw is low so not much voltage sag that could cause interaction throughout the circuit, gain stages are typically triodes (no screen voltage vs. gain -effect to concern about), stages actually contributing to clipping and harmonic distortion are few. In power amp you have much more interaction throughout the circuit, especially if it is a circuit that employs feedback: You have voltage sag of B+ and screen supply, which affect overall headroom and gain of the power tubes, you have saturation and cutoff clipping modes of the power tubes, one of them typically leading to clipping of the PI, especially in feedbacked systems. You have interstage capacitive coupling, which leads to bias shifts in overdrive conditions, and you have high impedance circuitry, which leads to weaker damping factor and to interactions with reactive characteristics of the speaker load. If you have to start removing one or few of the very few valves there, which one's they're going to be is going to be a quite tough call.
In that regard, OTLis a pretty strange choice of topology because it typically abandons all "classic" power amp architectures we favour in tube guitar amps, and substitutes them with a tube circuit, which is very solid-state-ish by architecture. The whole purpose of OTL were not musical warmth, sweet overdrive charcteristics at limited bandwidth, and poor damping of the louspeakers, but pretty much the opposite: It aims to achieve a better damping factor (fails), extends the bandwidth allowing more negative feedback, and has abrupt and harsh overdrive characteristics with no associated dynamic-effecting side effects that we search for from a tube power amp, bias shifts and sag.
Every sensible designer will also tell that far better results are achieved by using MOSFETs in the output instead of tubes.
One really interesting "OTL" topology replaces a traditional transformer with a switch-mode generic impedance converter circuit. A generic impedance converter is basically like a transformer in that it "reflects" impedance of its primary and secondary terminals, but the function is actually generated with operational amplifier circuitry. These amplifiers can operate in any class, but in high power systems powerful amplifiers are also needed since the conversion process is by no means efficient. Efficiency wise class-D, or any switching mode operation, makes sense. The topology does not have bandwidth restrictions of a generic transformer, nor - most importantly - as severe phase shifts as a real transformer, and it (especially in switch-mode-type) may also be more compact, cooler, lighter and cheaper than using a real output transformer.
The other benefit of this topology is that circuit's using it do not require huge architectural changes, one can retain to a traditional design and just substitute the traditional transformer element to SSGIC.
Traditional hybrid design hardly goes through such effort: Characteristics of a power amp circuit can be replicated in lower current, higher impedance circuits. These can be plainly re-amped, or which I think is pretty clever, hooked to an SSGIC, like Vox Valvetronix amps do.
Ok, maybe done with off topic now. Also, I agree: I'd hate to see this conversion turn into hostile argument where same old stuff gets rephrased again, and again, and again, and again...
Are you sure? Can you tell me a tube manufacturer that still makes PL519's today?
Best regards!
And yet, this supposed "falsehood" never actually existed. I never wrote "OTLs can only drive speakers with hundreds of ohms". Re-read my post and see for yourself!
OK- this is where I got that- if you meant something else, I would suggest a rewrite of this passage emphasis added):
Now in context, the prior post makes sense; if you meant it that way I've no argument! Where would one ever find a speaker impedance that high? However in the topic of the thread in general, ifeemeka's post was an interesting side comment, but if pursued would derail the thread.
??! This statement is blatently false. I think what you might not be understanding is that OTLs don't use the same power tubes as Marshalls and Fenders. You use tubes that are capable of high current and operate on lower voltages. The 6AS7G is a good example. A 6AS7G is ideally only good for about 10 watts and we are getting that much out of them in our products. So we are well above your '2%' figure, which I have to guess you must have been talking about a KT88 or the like? That's the only way that comment makes any sense.
Modify what amp?? If you are building an OTL, you don't start with a Marshall. You build the amp from the ground up and if you do it right they are quite practical on real world speakers. In my hifi set up, my listening position is about 9 feet from the speakers and I can hit 112 db (measured) at the listening chair without overloading the amps. So the quoted phrase above doesn't sound right at all.
One tube works great for headphones! But even there you have two sections, not one! I can get about 10 watts with a pair of 6AS7Gs; my speakers are 16 ohms. But keep in mind that is four sections, not just one. I operate the tubes class A2; I've been doing this for 40 years and over that time I've sorted out how to drive tubes when they are in an OTL circuit. Its not the same as when driving the grids of a pentode running an output transformer!
Seriously- you've not thought this through as far as I can tell! In this case your comment is actually false: It **would** be true for most people; I get full bandwidth (I limit it at 2Hz for hifi), and the speakers I use are mostly 16 ohms. At the shop they are 93 db 1 watt/1 meter and with 2 power tubes the room is easily filled. At home, again I have 16 ohms speakers but they are 98 db (not that different from many guitar speakers BTW) and I can achieve satisfying volumes with ease.
There are a lot of Hi-Fi speaker manufacturers that would dispute this point and might also be insulted by your assertion! Classic Audio Loudspeakers (US), Avantgarde (Germany), Tonian Labs (US), Horning, Cogent... as well as the usual suspects JBL, Altec, ElectroVoice and Klipsch.
Perhaps I have studied how the ear/brain system works more than yourself. There is exactly one transistor developed (by Sony, see http://www.diyaudio.com/forums/pass-labs/276711-sony-vfet-amplifier-part-2-a.html) that has the needed characteristics (triode like linearity combined with soft clipping- prevents odd ordered harmonic generation) in order to not make the higher ordered harmonics used by the human ear to gauge sound pressure (again: because the ear uses these harmonics as loudness cues, it is really incredibly sensitive to them!). All other semiconductor devices do; and since about 99% of the amps that use them also use loop negative feedback to linearize the amp, those designs will make higher ordered harmonics as well (see Norman Crowhurst for how feedback does this- his books can be downloaded free from Pete Millet's website tubebooks.org - Vintage info from the age of vacuum tubes).
IOW my generalizations are correct: they are based on objective research (Norman Crowhurst laid out the issues with feedback, then in the 60's General Electric demonstrated that the ear used odd ordered harmonics as loudness cues; their test is easy to replicate with simple test gear), which is quite plausible as a result!
Some of those brands I mentioned were out of business, others are not. And it was a limited list! The point is that OTLs have been in manufacture for the last 50 years. In your comments you make it sound like they are some sort of odd and impractical concept that never went anywhere!
Reality belies your comment. How it really works is you sort out first how much power you want to make, then you sort out what tubes to use and how many. You also have to understand that if you are working with a tube that is only good for 10 watts, you might have to use several (our 60 watt monoblock uses 8 per channel and does 60 watts into 8 ohms). Then there is the class of operation, and what speaker load is your target.
Sort those things out and the design of the amp might present itself if you understand the 'fundamental engineering factors'.
Possible tubes that are used in OTLs today: 6H13C (6AS7G), 6C33 (4 required to do 60-80 watts into 8 ohms), PL509, PL519. We're working on reintroducing the 7241 (two of those will easily do 50 watts into 8 ohms...).
I think you have this a bit wrong. OTL circuits are quite often based on very traditional tube designs. Ours was the first to employ more modern approaches that were more like semiconductor topologies. But we were not looking for particularly high damping factors as there is a lot more to life than just high damping factors. In fact, there are no speakers made that need more than 20:1, and there are a good number of speakers made that require considerably less!
So in my case at least (and being the oldest OTL manufacturer in the world, maybe the approach meant something...) the idea was to not generate the distortions to which the ear is keenly sensitive, and not to worry quite so much about the ones that it does not seem to care about (which traditionally is the 2nd harmonic, but we got rid of that one anyway). To this end, the circuit we came up with does not employ loop feedback and so has a higher output impedance.
I found that in this case, if you could get the speaker to work with the amp, it would immediately and obviously sound better than an amp that was running loop feedback (IOW, was more transparent, wider soundstage, deeper bass, stuff like that). The line became what sounded like real music as opposed to what sounded like a hifi.
Despite the higher output impedances we've been able to stay in business because there have always been plenty of speakers which work fine with the amps. So they've always been practical despite not meeting the goals you set out above.
When I built the OTLs for guitar, basically I limited the LF bandwidth and dispensed with a lot of the balanced circuitry I used in the hifi amps, in order to get a richer tone. I also limited the power supplies in order to get a bit of sag. With a high output impedance (a few ohms) and no feedback, a low damping factor was already in the mix. Really, the big problem was the speaker load and the fact that we ran four power tubes that guitarists aren't used to seeing. The speaker part was the easy part! Getting guitarists to play through an amp that has no pentodes is the hard part
Just for the record, the amp to which you refer is designed by David Berning but even he will tell you its not an OTL! OTLs by definition don't have an output transformer and the ZOTL amps most definitely have an output transformer! Take a look at the abstract on the patent.
There's an oops- sorry about that! It the EL509 that is still in production- made by JJ: www.thetubestore.com - JJ EL509-S Audio Tubes
It appears that the EL519 is still made in Russia.
hummmm eso pensé yo al ver los amplificadores de David Vering, no son muy cara a cara, demasiadas cosas en la cadena de la señal, siguen siendo necesarios un grupo de tubos a la salida numeroso, al menos 4,... por lo menos en los de guitarra, para mi manera de ver el tema, eso es complicarse mucho la vida, ahora si dice que suena bonito, bien yo lo creo, pero me parece otra cosa muy distinta, no es lo que yo veo como OTL puro, o estandar, aunque hay que apoyar cualquier trabajo en esta dirección, sea el que sea, como dije es otra opción más.....de otro tipo de amplificador y en otra clasificación distinta.
De Acuerdo con Atmasphere que en que en tema altavoces todo esta ya sobre la mesa y es como se ha dicho y la forma de conducir altavoces de Alta o baja impedancia ya es a gusto de cada uno, esta claro que los de 16 ohms son más estandar y documentados, yo he hecho pruebas con mis amplificadores y también se puede con cajs de 2x12" o 4x12" facilita mucho y bajando un poco la impedancia con el diseño del circuito.
A los guitarristas nos gustan los amplis potentes, en otl será similar, pero veo más potencial en los de baja tensión, pero al verse tan pequeños, ligeros, eficaces, bajo consumo, baratos, sencillos, asequibles...pudiera parecer otra cosa que no es,
aunque para mi, el de 0,5 a 2w y en 12v es el objetivo más revolucionario y deseado de todos.
pero aún así todo es atractivo, tambien de media y más alta potencia en guitarra.
Por eso he preferido construir todo un rango de potencias, para poder tener argumentos de peso, y otras valoraciones sin salirme de mi linea de trabajo.
Genobudy, estoy de acuerdo por otro lado con usted, porque si que se alcanzan sonoridades muy deseables y similares al estandar de la guitarra de alto nivel con estas soluciones sencillas....y otras cosas paralelas con su propia personalidad y quizás algún plus sobre lo conocido.
Usted comenta que le gustaron las dos muestras de sonido, gracias, supongo se refiere a los dos vídeos.
Creo que también será de su agrado una comparativa de los mismos amplificadores con numerosas guitarras, no se si lo vio, se lo dejo aquí :
Amplificadores de Válvulas OTL sin Transformador de Salída, Muestras de Sonido.
Otra cosa que deseo añadir es que ya es conocido lo bien que rinden los OTL con cascos de alta impedancia.
Otra ventaja, con unos cascos de alta impedancia tipo AKG 141 o tipo Senheiser 414 bien conocidos, el resultado con cualquier potencia es como poco sorprendente.
En el de 0,6w " the Atomic Ant" (esquema puesto en esta discusión) la misma salida de altavoz alimenta sin problema de manera real y directa unos auriculares AKG 141, es el amplificador mas real donde se cumple estrictamente lo de salida directa por triplicado.
, esto es otro plus...más.Puede parecer así, pero en mi caso como guitarrista encuentro varias razones:
Menor peso ( muy importante)
Menor costo , aumentando la calidad a la vez con algo muchísimo mas simple.
Simpleza.
Mantenimiento escaso y barato
Consumo bajo.
Todo a válvulas.
Pureza y linealidad del OTL, adios a perdidas de OT y adios a histéresis en salida, adios si se desea a los controles de tono innecesario, (aunque ya estamos muy acostumbrados a los abusos de los controles de tonos para tapar otras carencias estandar)
Sin renunciar ni al aspecto de los amplificadores de guitarra e incluso con valvulas estandar de los mismos. (Aunque se pueden utilizar cosas más raras claro).
El ampli en el que trabajo actualmente tiene 5y3 en rectificación, ecc82=12ax7/ o /ecc83=12au7 en previo y 2 EL34 en etapa de potencia.
De cara al guitarrista no ha cambiado nada, solo un plus en calidad y sencillez...lo que el guitarrista busca, enchufar su guitarra y a tocar.....y todo lo demás ya le es familiar, excepto que se asombra de que pesa tan poco, y a veces lo gracioso de que los que lo prueban se asombran de que un cono de solo 6" (800 oms) pueda sonar y rendir así, jajaja lo miran y remiran varias veces....
Los guitarristas debemos de ser un poco incredulos por naturaleza ;-)
Todo esto es algo muy muy bueno para la guitarra también.
************************
Ya solo me queda sacar una señal de linea para grabar externamente (directa si se puede de este gran pequeñin.)
Para la salida de linea quizás si les tenga que pedir opinión, ya que si fuera una salida estándar de señal desde trafo de salida, con dos sencillas resistencias ya valdría, al es
El texto supera los 5000 caracteres máximos permitidos.
TRADUCIR MÁS INGLÉS
Hummmm that I thought seeing the amplifiers David Vering, are not very face to face, too many things in the signal chain, a group of tubes are still needed at the output numerous, at least 4, ... at least In the guitar, for my way of seeing the subject, that is very complicated life, now if it says it sounds nice, well I believe it, but it seems to me something quite different, it is not what I see as pure OTL, Or standard, although you have to support any work in this direction, whatever, as I said is another option ..... of another type of amplifier and in another classification.
According to Atmasphere that in that in theme speakers everything is already on the table and is as it has been said and the way of driving loudspeakers of High or low impedance is already to taste of each one, it is clear that the ones of 16 ohms are more Standard and documented, I have tested with my amplifiers and also can with 2x12 "or 4x12" boxes facilitates a lot and lowering the impedance a bit with circuit design.
In guitarists we like powerful amps, in otl it will be similar, but I see more potential in low voltage, but because they are so small, light, efficient, low consumption, cheap, simple, affordable ... could seem something else It is not,
Although for me, 0.5 to 2w and 12v is the most revolutionary and desired goal of all.
But still everything is attractive, also of medium and higher power in guitar.
That is why I have chosen to build a whole range of powers, to have strong arguments, and other valuations without leaving my line of work.
Genobudy, I agree on the other hand with you, because if you achieve very desirable sonorities and similar to the standard of high-level guitar with these simple solutions .... and other things parallel with your own personality and perhaps some more about The known.
You comment that you liked the two samples of sound, thanks, I suppose it refers to the two videos.
I think it will also be to his liking a comparison of the same amplifiers with numerous guitars, not if he saw it, I leave it here:
Http://otl-fmk-amp.blogspot.com.es/2017/04/version-de-enclosure-de-diseno-para-el.html?m=1
Another thing I want to add is that it is already known how well OTLs perform with high impedance helmets.
Another advantage, with high impedance helmets type AKG 141 or type Senheiser 414 well known, the result with any power is not surprising.
In the 0.6w "the Atomic Ant" (schematic put in this discussion) the same speaker output automatically feeds a direct AKG 141 headphones, it is the most real amplifier where the direct output is strictly met by triplicate.
, this is another plus ... more.It may seem so, but in my case as a guitarist I find several reasons:
Lower weight (very important)
Lower cost, increasing quality at once with something much simpler.
Simplicity.
Spare and cheap maintenance
Low consumption.
Everything to valves.
Purity and linearity of the OTL, adios to OT losses and after hysteresis in output, adios if desired to unnecessary tone controls, (although we are already very accustomed to the abuses of the tone controls to cover other standard deficiencies)
Without giving up neither the look of the guitar amplifiers and even with standard valves of the same. (Although you can use rarer things of course).
The ampli I currently work has 5y3 in rectification, ecc82 = 12ax7 / o / ecc83 = 12au7 in previous and 2 EL34 in power stage.
Looking at the guitarist has not changed anything, just a plus in quality and simplicity ... what the guitarist looks for, plug in his guitar and play ..... and everything else is already familiar, except that he is amazed that It weighs so little, and sometimes the funny thing is that those who test it are amazed that a cone of only 6 "(800 oms) can sound and render like that, hahaha they look at it and they re-send several times ....
The guitarists must be a bit incredulous by nature ;-)
All this is very very good thing for the guitar as well.
*************************
I can only get a line signal to record externally (direct if you can of this great little one.)
For the line output, maybe if you have to ask for an opinion, since if it were a standard signal output from the output transformer, with two simple resistances it would already be worth, in the style of what Mr. Rob Robinete says in his modifications for Guitar amplifiers etc,
But being DC voltage and without trafo I'm a bit doubtful and I'm seeing the best way to add a line output or external recording in this little monster, any ideas ?. You atmasphere will surely have had to be in this situation ever before.
I suppose there will be several ways to do it, the voltage with speaker charge are about 5v DC.
What would be some advisable way for line output well adapted to record guitar ?, same with the same two resistors ?, some special care for DC voltage of the circuit.
**************************
FMK = (efeemeka in spanish
. )
As 12V and 0.5 to 2W usually call for solid state, I have to ask you what types of output valves you're intending to use?
Best regards!
As I said in this forum a little later I am very pleased and a very special valve and low impedance output ,
With a specific physical structure for the types that are called double impulse, it is a double aid to the electrons to give an extra boost and that can work in + B only at 12 volts, (actually and effectively from 9 to 30v , With higher voltage of 12v higher performance, although it is expected to increase a little impedance as is reasonable,
At 12 volts with the described circuit delivers 600 ohms (ohms) and 0.6 or 0.7 watts approx, with 1/2 triode.
For guitar I use a pre boster, the BSIAB II, for hifi or line or reproduction from a source type signal standard vale without preboster.
This valve is the 12k5, used in vintage car radios
But there are others similar, we are in luck
regards
,With a specific physical structure for the types that are called double impulse, it is a double aid to the electrons to give an extra boost and that can work in + B only at 12 volts, (actually and effectively from 9 to 30v , With higher voltage of 12v higher performance, although it is expected to increase a little impedance as is reasonable,
At 12 volts with the described circuit delivers 600 ohms (ohms) and 0.6 or 0.7 watts approx, with 1/2 triode.
For guitar I use a pre boster, the BSIAB II, for hifi or line or reproduction from a source type signal standard vale without preboster.
This valve is the 12k5, used in vintage car radios
But there are others similar, we are in luck
regards
No, what I want is to feed it with insulated wallwashing transformers plus good grounding added on the external ones and a standard transformer in which they go inside the equipment.
The consumption is not much, I have them working with a simple plug of wall-mounted on those lower power models. Although I guess it could be used with this model battery but for now I have not had the need.
The highest power, with Valve 5y3 for 5w and 25w or more.
The consumption is not much, I have them working with a simple plug of wall-mounted on those lower power models. Although I guess it could be used with this model battery but for now I have not had the need.
The highest power, with Valve 5y3 for 5w and 25w or more.
Dropbox - DSCN1411.JPG
Dropbox - DSCN1411.JPG
Dropbox - DSCN1415.JPG
There is here in Madrid a craftsman builder who manufactures loudspeakers, combos boxes and heads and furniture for amplification with an exquisite taste and very high sound quality, are the dress that I want for my OTL guitar amps, to see what they look like , Has good taste and are already works very recognized locally and internationally, is called LCA guitars, also consyruye cigarbox and a long experience.
Is what I prefer for my OTL to be artisans and with a classic and vintage touch.
Dropbox - DSCN1411.JPG
Dropbox - DSCN1415.JPG
There is here in Madrid a craftsman builder who manufactures loudspeakers, combos boxes and heads and furniture for amplification with an exquisite taste and very high sound quality, are the dress that I want for my OTL guitar amps, to see what they look like , Has good taste and are already works very recognized locally and internationally, is called LCA guitars, also consyruye cigarbox
and a long experience.Is what I prefer for my OTL to be artisans and with a classic and vintage touch.
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Otl of guitar eléctric whit 2 EL34, pictures speaker of 600 ohms
One equip beautifull of see
OTL EL34 - Google Drive
One equip beautifull of see
OTL EL34 - Google Drive
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I have much time in see how can more power at OTL single in 12v topology for Double impulse tubes,
And I have this implementing of one single form.
In the 12v of the this otl's whit +B at 12v, transform this at +B 30v, this supuse one increment in the power whit one only tube very netcesary and more headroom whit one speaker of 800 ohms.
I construct this in one enclosure type Fender champ bñackface OTL
And this supuse one more optión or solutión very single at the small amp guitar world, and very utility.
And I have this implementing of one single form.
In the 12v of the this otl's whit +B at 12v, transform this at +B 30v, this supuse one increment in the power whit one only tube very netcesary and more headroom whit one speaker of 800 ohms.
I construct this in one enclosure type Fender champ bñackface OTL
And this supuse one more optión or solutión very single at the small amp guitar world, and very utility.
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I joy this Otl amp, whit standar speakers.
Whit standars speakers of 16 and 8 ohms. ( Celestion and Eminence for guitar players)
Whit only one valve in power sectión,( And whit 800 ohms too).
An in this monts i eliminate too I eliminate the D.C. component to speaker, for have more segurity in this. In the speakers is good not have dc to cone.
And this is direct output, whitoutht not capacitive acopled,, and not negative feedback.
Direct direct, an not colours much the signal.
The solution for more volume in this small amps, and have volume for practice for guitar is :
1 ) atack the previo the big posible, i put guitars pedal in the imput, one, two...in the signal is big whit this. Or one previous whit much signal.
2 ) +B of 12v to 30v ( whit 12k5 tube).
3 ) select speakers of big presure of sound 100 to 103 db.
Whit all this i have, need put to potentiometer of volume( of amp or pedals) at 1/3 of total , jeje in my salon inclusive whit estandar speakers for normal práctice.
Sorry my bad english write traductión !
Other plus + , at all this, can be conver this Otl amp in portable.
This work whit 12v , whit one ups batery or other of 1,5 to 2 amperes convert the Amp in one beautiful champión portable !!!.
This song good for my head.
I very happy
And one big avanced
The OTL in 12v. Work, and very good.
The 12k5 tube is ideal for this portable finality,
The tube is create for this specific purpose for olds casettes cars, and batery of 12v
The first OTL Portable guitar amp?
I can not say ....but this is big.
Good day. Otl readers
Whit standars speakers of 16 and 8 ohms. ( Celestion and Eminence for guitar players)
Whit only one valve in power sectión,( And whit 800 ohms too).
An in this monts i eliminate too I eliminate the D.C. component to speaker, for have more segurity in this. In the speakers is good not have dc to cone.
And this is direct output, whitoutht not capacitive acopled,, and not negative feedback.
Direct direct, an not colours much the signal.
The solution for more volume in this small amps, and have volume for practice for guitar is :
1 ) atack the previo the big posible, i put guitars pedal in the imput, one, two...in the signal is big whit this. Or one previous whit much signal.
2 ) +B of 12v to 30v ( whit 12k5 tube).
3 ) select speakers of big presure of sound 100 to 103 db.
Whit all this i have, need put to potentiometer of volume( of amp or pedals) at 1/3 of total , jeje in my salon inclusive whit estandar speakers for normal práctice.
Sorry my bad english write traductión !
Other plus + , at all this, can be conver this Otl amp in portable.
This work whit 12v , whit one ups batery or other of 1,5 to 2 amperes convert the Amp in one beautiful champión portable !!!.
This song good for my head.
I very happy
And one big avanced
The OTL in 12v. Work, and very good.
The 12k5 tube is ideal for this portable finality,
The tube is create for this specific purpose for olds casettes cars, and batery of 12v
The first OTL Portable guitar amp?
I can not say ....but this is big.
Good day. Otl readers
Hi
Wasn't there a company called Victor, or something like that, that made an OTL guitar head? Their site had a pic of a band that looked like the Three Stooges comedy brothers.
OTL as a tube amp is not very efficient, so what you gain by losing the weight of an OT you lose by reduced power or extra weight in the OT or by having to use wierd tubes.
Wasn't there a company called Victor, or something like that, that made an OTL guitar head? Their site had a pic of a band that looked like the Three Stooges comedy brothers.
OTL as a tube amp is not very efficient, so what you gain by losing the weight of an OT you lose by reduced power or extra weight in the OT or by having to use wierd tubes.
How does 50 watts sound in a combo, weighing less than a Fender twin and better able to project? That's with 4 power tubes and tubes don't weigh that much. The efficiency of an OTL depends entirely on the load and its not that hard to come up with a real world load that a smaller OTL can drive.
I use 6AS7Gs. They are weird but they're still cheap and apparently still in production (China).
Yes for 20w it is good and generic more people. And 50w for scenary play is good.
Atmasphere , ¿ For 2x 6AS7Gs, are aprox. 20w? Or less for 100db speaker? And in output at speaker te voltage is big?, ¿How of big in volts.? Whit 2 6AS7Gs can go to be.?
Is netcesary bind or aislate the cable line and not put conections in the air or chasis for combo and head supuse.
In low voltage and in higth voltaje the sound is good in direct output (low voltage) and capacitor acoplate ( in higth voltage) And the saturate in big volumen amp only sume, not bad Not is very netcesary none type of negative realimentatión for guitar, uh
Thanks
Atmasphere , ¿ For 2x 6AS7Gs, are aprox. 20w? Or less for 100db speaker? And in output at speaker te voltage is big?, ¿How of big in volts.? Whit 2 6AS7Gs can go to be.?
Is netcesary bind or aislate the cable line and not put conections in the air or chasis for combo and head supuse.
In low voltage and in higth voltaje the sound is good in direct output (low voltage) and capacitor acoplate ( in higth voltage) And the saturate in big volumen amp only sume, not bad Not is very netcesary none type of negative realimentatión for guitar, uh
Thanks
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