Hi Guys , Im prety new to tubes but have done a lot of Solid state stuff so Im not new to electronics so I have some general tube questions a questions about some Mystery tubes I have so I can attempt a tube project (guitar amp)......
1
I was wondering about Grounding , specificly , do you tie the heater Ground and the plate ground together ?? And if not were does the audio ground go ??
2 What is the output AC Voltage (audio signal) of a Tube like a 12ax7 at full gain ?? Does the Voltage go up considerably after several Tube stages or does it just hit a certain clipping threshold ??
3 I found a busted home made Tube amp that has some tubes in it that aren"t really labeled and was wondering if you guys might have a clue what they are....
The first one has 5 Pins and has UY above 76 inside a stop sign shaped circle , its shaped like 6V6 but about 25% smaller .....
The other one is the same size and shape but has 6Z above P1 inside a stop sign shaped circle , but this one has 6 pins .....
There is one more that I cant find right now but I think it is a rectifier tube as it only has 3 pins ....
The amp also has a small 6 in speaker and a small output transformer and a small power transformer .......
Thanx Guys !!!
1
I was wondering about Grounding , specificly , do you tie the heater Ground and the plate ground together ?? And if not were does the audio ground go ??2
What is the output AC Voltage (audio signal) of a Tube like a 12ax7 at full gain ?? Does the Voltage go up considerably after several Tube stages or does it just hit a certain clipping threshold ??3
I found a busted home made Tube amp that has some tubes in it that aren"t really labeled and was wondering if you guys might have a clue what they are....The first one has 5 Pins and has UY above 76 inside a stop sign shaped circle , its shaped like 6V6 but about 25% smaller .....
The other one is the same size and shape but has 6Z above P1 inside a stop sign shaped circle , but this one has 6 pins .....
There is one more that I cant find right now but I think it is a rectifier tube as it only has 3 pins ....
The amp also has a small 6 in speaker and a small output transformer and a small power transformer .......
Thanx Guys !!!
1
Depending on the tube used. With indirectly heated tube you can leave it floating or tie it at a fixed positive potential. With directly heated tube you have no choice but to tie it to ground at one point.
2
Amplification factor of 12AX7 is 100 in theory and somewhere between 55-60 in practice. Output swing depends on input swing and supply voltage (it cannot go past supply rails, obviously).
The followup question makes no sense (to me at least): of course the voltage goes up in cascaded stages with gain larger than unity and of course it can get into clipping eventually.
3
Photos will go great length further than text description.
Hi , Thanx for the explanation but now I"m more confused than before ....
What is an Indirectly heated tube as opposed a directly heated tube ??
I only know about takeing a seperate winding off the transformer and either Powering the Tubes heaters with AC or rectified Filtered DC , and was wondering if I tie the DC Heater ground to the Plate supply ground , or if I use AC do I just leave it floating ?
My question about output voltage and clipping has to do with in solid state you go into clipping when the output voltage approaches the supply voltage , But in tubes the Supply Voltage is upwards of 350v so it wouldn"t go into clipping till it appraches 350v , which would take quite a few tubes at max gain and a 200mv guitar signal to get it to clip but we all know you can get a single tube to clip, as they do in many guitar amps .......
So that was why I was asking , also if I wanted interface a High gain Tube preamp with a solid state Power amp I would need to know what type of output Voltage I would expect so I could suitably Pad it down .....?
As for Pictures of the Tubes I can"t do that as I am one of those loosers that doesn"t have a camera as I can"t justify spending money on something I will use once a year, but there is absolutely nothing on the tubes accept for what i described .....
Maybe I need to ask this differently , what types of tubes have 5 pins ?? and what type of 6 pins ?? (EG: Triode , Pentode ect)
Thanx a Lot ....Cheers
What is an Indirectly heated tube as opposed a directly heated tube ??
I only know about takeing a seperate winding off the transformer and either Powering the Tubes heaters with AC or rectified Filtered DC , and was wondering if I tie the DC Heater ground to the Plate supply ground , or if I use AC do I just leave it floating ?
My question about output voltage and clipping has to do with in solid state you go into clipping when the output voltage approaches the supply voltage , But in tubes the Supply Voltage is upwards of 350v so it wouldn"t go into clipping till it appraches 350v , which would take quite a few tubes at max gain and a 200mv guitar signal to get it to clip but we all know you can get a single tube to clip, as they do in many guitar amps .......
So that was why I was asking , also if I wanted interface a High gain Tube preamp with a solid state Power amp I would need to know what type of output Voltage I would expect so I could suitably Pad it down .....?
As for Pictures of the Tubes I can"t do that as I am one of those loosers that doesn"t have a camera as I can"t justify spending money on something I will use once a year, but there is absolutely nothing on the tubes accept for what i described .....
Maybe I need to ask this differently , what types of tubes have 5 pins ?? and what type of 6 pins ?? (EG: Triode , Pentode ect)
Thanx a Lot ....Cheers
Hi,
Iam a newbie too. In direct heating the AC or DC heats the Cathode itself, and in the Indirect Heating the AC or DC voltage heats a filament near the Cathode that heat the cathode by radiation(no physical contact).
For HiFi use DC heating is best sound and more expensive, maybe in guitar amp you can use AC heating.
This is my two cents, Gustavo
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Quote>> Maybe I need to ask this differently , what types of tubes have 5 pins ?? and what type of 6 pins ??
Looks it could be a Single Triode or a Single Pentode respectively...
The Double Triode 12AX7 family have 9 pins, Single Triode like 572/211/845 power tubes are 4 pins.
Regards, Gustavo
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Hi , Thanx , I just found a bit of info on the tubes I have, They are Old Japanese tubes , the 6ZP1 I believe is a Pentode as it says it is good for 1w output , and the UY76 is a single triode , there is Very little info on these tubes on the net accept in Japanese which doesn"t Translate well ....
I"ll just scap the idea of useing these tubes and just use the Power transformer for a 12ax7 Tube preamp project ......
Maybe someone will help with my other questions ....
Thanx
I"ll just scap the idea of useing these tubes and just use the Power transformer for a 12ax7 Tube preamp project ......
Maybe someone will help with my other questions ....
Thanx
I know it's tempting to ask a series of questions, since there's a seemingly endless source of replies out here, but simple questions like this, and quite a lot of more complex ones, can be answered for yourself with google.
Yes, valve amplifiers clip. If you think about it tho', they use high voltages. This means small currents (otherwise the powers would be very large), and that means high impedances compared with solid state circuits (in general). It means transformers to drive speakers. Interstage voltages and currents all need to be planned tho' to meet the requirements of the various stages.
If you can design a SS amplifier, then you can probably plot a load line. If you plot a load line on a valve characteristic, you can see the input and output voltages, and the voltage gain, etc., etc. Again there are tutorials on this and simulators, some dedicated to valves.
w
This question doesn't make any sense. If it's a directly heated tube, you can't leave its heater supply floating, otherwise the circuit won't be completed and no current will flow. If it's an indirectly heated tube we're talking about you can do either.
This is not a question, this is a statement, and confusing one at that. I can't think of a way to get a single 12AX7 stage to clip with 200 mV p-t-p input and 350V anode voltage (nevermind exceeding the maximum rating ...) in a simple common cathode configuration. But yeah, if a tube with sufficiently high amplification factor was used and the load presented to it was very large, it could go into clipping with 200 mV input (think pentode + CCS load).
Depends on tube, topology and exact component values; the only correct answer would be "any and all". Anything from 0V to about as much as anode supply voltage is doable (peak to peak).
Perhaps your mobile phone has a camera ? Most of these come with one nowadays, under reasonable light it will substitute for the real thing just fine.
It doesn't work this way - there are different types of bases, UX5 being an example of 5-pin base and "27" (triode), ""47" (pentode) etc. being examples of different tube types using same UX5 base. This is not unlike solid state world where you can find BJTs, diodes, FETs, complex ICs, triacs, thyristors, etc. all tucked into same plain TO-220 package.
You need to determine tube type by its name and/or manufacturing code, then we might be able to give you answers that pertain to your tubes only and not to tubes in general (which is what you're asking now).
@ Minion
Go out and get yourself a copy of Morgan Jones "Valve Amplifiers 3rd Edition" as this will give you a very solid foundation upon which to build your understanding.
Presumably having dabled with solid state you understand the very fundamentals of electronic theory - if not you should probably study up on Ohm's Law, Thevenin's and Norton's theorems, and the behavior of inductors, capacitors and resistors as a minimum..
Good construction practices can be learned from you guessed it: Morgan Jones "Building Valve Amplifiers"
For anyone who loves audio electronics these two titles are extremely entertaining reading, and IMHO if anything is a must read these titles are it.
Online (Pete Millett's site, etc.) look for old Norman Crowhurst articles. Back issues of Audio Amateur, Glass Audio, and the current AudioXpress are also sometimes good sources of newbie learning.
Most of all don't give up! Building your first tube project will be rewarding as you learn how to do things, and finally get it working. There will be plenty of help here..
Go out and get yourself a copy of Morgan Jones "Valve Amplifiers 3rd Edition" as this will give you a very solid foundation upon which to build your understanding.
Presumably having dabled with solid state you understand the very fundamentals of electronic theory - if not you should probably study up on Ohm's Law, Thevenin's and Norton's theorems, and the behavior of inductors, capacitors and resistors as a minimum..
Good construction practices can be learned from you guessed it: Morgan Jones "Building Valve Amplifiers"
For anyone who loves audio electronics these two titles are extremely entertaining reading, and IMHO if anything is a must read these titles are it.
Online (Pete Millett's site, etc.) look for old Norman Crowhurst articles. Back issues of Audio Amateur, Glass Audio, and the current AudioXpress are also sometimes good sources of newbie learning.
Most of all don't give up! Building your first tube project will be rewarding as you learn how to do things, and finally get it working. There will be plenty of help here..
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Hey Kevin , Ive actually been doing electronics for maybe 6 years and have built several amps and designed many circuits and designed and built most of the equipment I use in my Studio , Most of it Solid state but My latest guitar amp that I built has a Tube preamp in it , but it is a Low Voltage tube preamp , the Plate runs at 45v DC and the heaters are 12VAC , the Thing is the Plate Voltage is just Made From a Voltage tripler from the 12v AC Heater Voltage so the grounds are the same Hence my question about grounding the heaters and Plate Voltage to the same point ..... which was really the only pressing question I had , but I thought since this is a forum for asking questions to awesome poeple and geting a reliable answer that i would ask a few more but I guess that was a mistake.....
Look , I"m not asking someone to explain Tube theory to me I"m just asking a couple seemingly simple questions here (Does the DC heater Ground connect to the Plate DC Ground? , I can figure out the Output Voltage thing myself ) and I know you mean well but it doesn"t help me for you to tell me to read a Book when someone can just give me a simple answer , you know , out of the Kindness of there hearts .......?
Thanx
Look , I"m not asking someone to explain Tube theory to me I"m just asking a couple seemingly simple questions here (Does the DC heater Ground connect to the Plate DC Ground? , I can figure out the Output Voltage thing myself ) and I know you mean well but it doesn"t help me for you to tell me to read a Book when someone can just give me a simple answer , you know , out of the Kindness of there hearts .......?
Thanx
Heater reference can be confusing. For indirectly heated tubes there is sometimes an advantage to referencing to a voltage above ground to help reduce hum. On a guitar amp I built I did this simply by connecting the heater center tap (for the 6V heaters not the rectifier heater) to the cathode of the output tubes. The output tubes were self biased so that point was + with respect to the chassis ground.
One thing to watch out for though is that different tubes have different specs on the maximum voltage differential between their heaters and their cathodes. Depending on the circuit and the tubes involved this could become an issue. Best to check your design against the tube data sheets to be sure.
I have not done any DC heaters so I can't really comment on that.
Look forward to seeing what you are building.
One thing to watch out for though is that different tubes have different specs on the maximum voltage differential between their heaters and their cathodes. Depending on the circuit and the tubes involved this could become an issue. Best to check your design against the tube data sheets to be sure.
I have not done any DC heaters so I can't really comment on that.
Look forward to seeing what you are building.
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