hello,
I have a 90's 10watt SS guitar Practice amp with volume and master controls that is extremely versatile for different ranges of sound, I love it but there are ranges of setting where the tone starts to go a pretty dull and flat..
theres a 12vac transformer sitting around in my box of bits so i thought about getting a tube pre/buffer kit since there is room in the chassis so thought about mucking round with it.
I have built ss amps and high voltage tube preamps before following existing designs so I am aware of the basics like proper grounding, layout, fusing, safety etc.
unfortunately i have trouble with the maths and selecting anode, cathode voltage resistance etc and matching gain stages/levels. so really need some help.anyhow the idea......
is to alter one of the two stereo kits below in the schematics as a pre and possibly cut and jump the kits pcb to run the stereo channels in to each other as two stage mono buffer and maybe drive the second half of the tube or other.
the designs use lower voltage than most tube amps +/- 30v so im not sure if it will be possible to use one stage to drive the other into overdrive?
I'm not sure what adjustments to make, adding cathode capacitors and anode resistors and which kit/design would be better to use? i saw one has series heater wiring, not sure if that is a good idea. one design uses both halves of a 6n3 the other uses two 6j1's. any help, scribbles and advice would be great thanks
ps just noticed is the 5v heater reg receiving ac on the 6n3 schem? and why did they not reg to 6.3v or 6v at least with a 317 or something.
.
I have a 90's 10watt SS guitar Practice amp with volume and master controls that is extremely versatile for different ranges of sound, I love it but there are ranges of setting where the tone starts to go a pretty dull and flat..
theres a 12vac transformer sitting around in my box of bits so i thought about getting a tube pre/buffer kit since there is room in the chassis so thought about mucking round with it.
I have built ss amps and high voltage tube preamps before following existing designs so I am aware of the basics like proper grounding, layout, fusing, safety etc.
unfortunately i have trouble with the maths and selecting anode, cathode voltage resistance etc and matching gain stages/levels. so really need some help.anyhow the idea......
is to alter one of the two stereo kits below in the schematics as a pre and possibly cut and jump the kits pcb to run the stereo channels in to each other as two stage mono buffer and maybe drive the second half of the tube or other.
the designs use lower voltage than most tube amps +/- 30v so im not sure if it will be possible to use one stage to drive the other into overdrive?
I'm not sure what adjustments to make, adding cathode capacitors and anode resistors and which kit/design would be better to use? i saw one has series heater wiring, not sure if that is a good idea. one design uses both halves of a 6n3 the other uses two 6j1's. any help, scribbles and advice would be great thanks
ps just noticed is the 5v heater reg receiving ac on the 6n3 schem? and why did they not reg to 6.3v or 6v at least with a 317 or something.
.
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You know, using a voltage doubler to produce +28 v like the first schematic is not going to get much output power. Likely to be unimpressive.
The second amp at least shows 30v coming magically from somewhere. I suggest, as a regular Salvation Army resale shopper, a 32 v power supply from a copier/fax/printer machine. I used one recently for a power supply for a zimblestern motor.
I also suggest if you are an electric guitar or bass player, a used amp or a kit of one of the classics. Fender, Ampeg or others, knew how to make them sound. There are copy kits sold by various guitar parts shops, the one I trade with is tubesandmore.com.
The main advantage of tubes IMHO is the soft hit red plate distortion of the output tubes, giving second harmonics. You're not going to get much red plate with a 28 v supply.
I just got a 120 watt rms capable 10" speaker from partsexpress for $15, so limiting oneself to 10 watts is again extreme economy. It is a great power to learn your 6 basic chords, but time to move on to something real IMHO. A Peavey 10" (really 9.5") speaker capable of 400 W program is about $55.
There are guitar amp parts shops in OZ, I've seen various posts on here but haven't logged their name because I live half a world away.
The second amp at least shows 30v coming magically from somewhere. I suggest, as a regular Salvation Army resale shopper, a 32 v power supply from a copier/fax/printer machine. I used one recently for a power supply for a zimblestern motor.
I also suggest if you are an electric guitar or bass player, a used amp or a kit of one of the classics. Fender, Ampeg or others, knew how to make them sound. There are copy kits sold by various guitar parts shops, the one I trade with is tubesandmore.com.
The main advantage of tubes IMHO is the soft hit red plate distortion of the output tubes, giving second harmonics. You're not going to get much red plate with a 28 v supply.
I just got a 120 watt rms capable 10" speaker from partsexpress for $15, so limiting oneself to 10 watts is again extreme economy. It is a great power to learn your 6 basic chords, but time to move on to something real IMHO. A Peavey 10" (really 9.5") speaker capable of 400 W program is about $55.
There are guitar amp parts shops in OZ, I've seen various posts on here but haven't logged their name because I live half a world away.
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Thanks, I have lots of powerful tube and solidstate amps genuine 50's 60's 70's 80's 90's, probably enough to blow out my neighbors windows. this is really just a fun project i want to muck around with. I like to re-cycle broken stuff and use the parts from different era's to create sound, some times its easy to get a cheap kit and load it with some quality parts. I have higher voltage ss transformers if the voltage dubler circuit is no good. Anyhow its only to add to the pre-section, im not using it as a power amp. i have a ton of speakers already. thanks for the shopping tip, will still do the experiment though.
Experimenting is fun.
Actually the transistor part of both these schematics appears to be the power supply regulator, and that a rather old fashioned one. TO92 package (.5 W) transistors as regulators don't put out much current. I use TIP142/147 darlington transistors as regulators in a TO247 package with a heat sink, with 1 W zener diode stacks driving the base lead for whatever voltage I want (-1.5). Use a resistor from raw high voltage to the zener diodes stack to limit the current to whatever they can take, go for about 1/2 watt on 1 watt diodes. Each TIP147 (for positive) can put out about an amp and a quarter.
I really don't see the advantage of tubes for a preamp part, they use a lot of power and are shock fragile for just a linear output. Tubes are great as output devices, because of the red plate compression gives "that sound". My PAS2 12AX7 linear preamp still works, but draws 125 W for a job that can be done for 7 W with op amps. I used a surplus wall-transformer to power the op-amp mixer, that eliminated an internal transformer & power switch that caused a lot of hum. 18 v transformer from a car race set turns into +- 8v easily with a couple of 5 w zener diodes, some current limiting resistors, and appropriate electrolytic caps in & out.
The quietest cheapest op amps are ST33078, but 5532 is quiet too if you can get them (often out of stock at farnell here).
I get enough of tubes with my organs, the H100's have 23 each. The one with 72 new e-capacitors works okay, but I have to shake the tubes in the sockets sometimes to get a reconnect and passage of sound. With all the weight the H100 are not road worthy. Not unless you tow a battery forklift behind your van.
Have fun.
Actually the transistor part of both these schematics appears to be the power supply regulator, and that a rather old fashioned one. TO92 package (.5 W) transistors as regulators don't put out much current. I use TIP142/147 darlington transistors as regulators in a TO247 package with a heat sink, with 1 W zener diode stacks driving the base lead for whatever voltage I want (-1.5). Use a resistor from raw high voltage to the zener diodes stack to limit the current to whatever they can take, go for about 1/2 watt on 1 watt diodes. Each TIP147 (for positive) can put out about an amp and a quarter.
I really don't see the advantage of tubes for a preamp part, they use a lot of power and are shock fragile for just a linear output. Tubes are great as output devices, because of the red plate compression gives "that sound". My PAS2 12AX7 linear preamp still works, but draws 125 W for a job that can be done for 7 W with op amps. I used a surplus wall-transformer to power the op-amp mixer, that eliminated an internal transformer & power switch that caused a lot of hum. 18 v transformer from a car race set turns into +- 8v easily with a couple of 5 w zener diodes, some current limiting resistors, and appropriate electrolytic caps in & out.
The quietest cheapest op amps are ST33078, but 5532 is quiet too if you can get them (often out of stock at farnell here).
I get enough of tubes with my organs, the H100's have 23 each. The one with 72 new e-capacitors works okay, but I have to shake the tubes in the sockets sometimes to get a reconnect and passage of sound. With all the weight the H100 are not road worthy. Not unless you tow a battery forklift behind your van.
Have fun.
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