Even if the volume on the laptop is turned to the max the Aleph is in no way challenged and neither are the speakers. I can't imagine this wrong thing that you imagine that would be so loud and bad as to blow things up . I think you have a wild imagination Jean-Paul.
I could more easily imagine something burning inside the Aleph from no particular reason, just a component failure. I hope it doesn't for a very long time as I love this amp.
No wild imagination at all but simple experience and some facts. Your imagination tells you they blow up as I did not write that, they will overheat/burn. With normal 2Vrms outputs and a "open" power amplifier with 1.5Vrms input sensitivity many can testify that when the input signal level goes to maximum for some unexpected reason the amplifier will amplify that input signal multiplied with its gain and it will then also be overdriven (distortion so likely high DC component) and this will be very loud and damaging unless someone is there to dive to the power switch.
In your case volume can be limited in software or something like that (which still is software and software sometimes fails) or it might be the odd one that has low line output level. I am the guy they call when the woofers are burnt so I have seen quite some setups with let's say streamers with 2V rms outputs directly connected to power amplifiers without volume control with these results.
If the setup with the laptop does allow maximum volume (what when you switch to a source that does do 2Vrms?) then it still is better to have output levels of the source set to max and use hardware volume control. It is a simple test to do by ear.
In your case volume can be limited in software or something like that (which still is software and software sometimes fails) or it might be the odd one that has low line output level. I am the guy they call when the woofers are burnt so I have seen quite some setups with let's say streamers with 2V rms outputs directly connected to power amplifiers without volume control with these results.
If the setup with the laptop does allow maximum volume (what when you switch to a source that does do 2Vrms?) then it still is better to have output levels of the source set to max and use hardware volume control. It is a simple test to do by ear.
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'Heater wiring: If your heater winding/supply voltage is 6.3 volt
Solder a short wire in-between pin 4 and 5. Now connect you 6.3 volt supply to pin 3 and 4. You are done.'
Dear Wot, since your heater supply is 12 volt and if one wire is connected to pin4 and the other to pin5 then it is fine. 13 volt instead of 12.6 volt is not a big problem. You can use your metal cabinet as ground plane as temporary measure. I am telling this because I want the system up and running. We can fix small problem like hum etc. afterwards.
Yet if you find your plate voltage voltage is 13 volt replace plate CCS with a 6K-8K 10 watt resistor. What is your B+ voltage it's important to know.
Dear jean-paul, I am a firm believer in proper gain structure. But I am encouraging Wot to build this pre so that be learns the build process and afterwards, if need be, he can build a tube buffer stage.
Regards
Solder a short wire in-between pin 4 and 5. Now connect you 6.3 volt supply to pin 3 and 4. You are done.'
Dear Wot, since your heater supply is 12 volt and if one wire is connected to pin4 and the other to pin5 then it is fine. 13 volt instead of 12.6 volt is not a big problem. You can use your metal cabinet as ground plane as temporary measure. I am telling this because I want the system up and running. We can fix small problem like hum etc. afterwards.
Yet if you find your plate voltage voltage is 13 volt replace plate CCS with a 6K-8K 10 watt resistor. What is your B+ voltage it's important to know.
Dear jean-paul, I am a firm believer in proper gain structure. But I am encouraging Wot to build this pre so that be learns the build process and afterwards, if need be, he can build a tube buffer stage.
Regards
Hi Minhaj,
I connected all the earths and it works. Kindof. It doesn't make horrible noises, it plays music through but the level is lower and more distorted than without it in the line.
I have yet to replace the 10M45's with those resistors as that's a trip to town. I won't be driving 30minutes each way just for those so it will have to wait till next week.
There is satisfaction in actually getting it to kind of function but it is looking as if Jean-Paul is correct concerning the Aleph not needing a preamp.
So once I fit those resistors and test it again will you tell me about the Amp you are planning to build?
Also you wanted to know the voltage at B+ but I'm not sure where to measure it from.
If I take it from the junction of the 390K resistors it is about 9V.
If I go from the negative on the bridge rectifier it's 190V.
Cheers.
I connected all the earths and it works. Kindof. It doesn't make horrible noises, it plays music through but the level is lower and more distorted than without it in the line.
I have yet to replace the 10M45's with those resistors as that's a trip to town. I won't be driving 30minutes each way just for those so it will have to wait till next week.
There is satisfaction in actually getting it to kind of function but it is looking as if Jean-Paul is correct concerning the Aleph not needing a preamp.
So once I fit those resistors and test it again will you tell me about the Amp you are planning to build?
Also you wanted to know the voltage at B+ but I'm not sure where to measure it from.
If I take it from the junction of the 390K resistors it is about 9V.
If I go from the negative on the bridge rectifier it's 190V.
Cheers.
Congratulation! I am more than happy that it makes sound. This is big thing for us.
B+ should be measured from +side of 33uf cap to ground. If it is 190 volt your plate resistor will be 5k 10 watt for 90 volt plate voltage @ 20ma plate current.
Please measure B+ once again and confirm.
Once you replace 10M45 with 5k resistor you need to bypass the cathode resistor with 220uf 16-25 volt Elna Silmic II capacitor. Please check if 500 ohms resistor is installed in-between cathode pin (pin no 1) and ground. cathode bypass cap also should be connected in-between cathode pin (pin no 1) and ground.
Since now your plate voltage is 13 volt only and it is passing very little current instead of 20ma the sound is distorting. Once the biasing is done properly you will be rewarded with beautiful sound.
Since many of us use more than one source (CD is 2 volt, tape, tuner and phono is 500mv-1volt) in real life a pre should have 3x-4x gain. This is my take. By the way 12B4A gain after insertion and other losses will be max 5x. My DHT pre with 3a5 battery tube in para-feed config has 3x gain. It is perfect for my CD player (heavily modified with 1.3 volt output) as well my phono and tuner.
My main system is heavily modified Fostex 206 in Fostex 208 back loaded horn cab driven with home made two stage AC coupled 300b se amp. My next project is 12'' high effc. cone driver in 60L sealed cab and 2'' comp driver in 300Hz tractrix front horn. Both the bass cabs and front horns are already constructed. I will install the drivers soon. The bass cabs I will drive with 50watt-100watt solid state amp and the 300hz horns will be driven with DC coupled el84/6V6 or 2A3 amp.
Again, congratulation!
B+ should be measured from +side of 33uf cap to ground. If it is 190 volt your plate resistor will be 5k 10 watt for 90 volt plate voltage @ 20ma plate current.
Please measure B+ once again and confirm.
Once you replace 10M45 with 5k resistor you need to bypass the cathode resistor with 220uf 16-25 volt Elna Silmic II capacitor. Please check if 500 ohms resistor is installed in-between cathode pin (pin no 1) and ground. cathode bypass cap also should be connected in-between cathode pin (pin no 1) and ground.
Since now your plate voltage is 13 volt only and it is passing very little current instead of 20ma the sound is distorting. Once the biasing is done properly you will be rewarded with beautiful sound.
Since many of us use more than one source (CD is 2 volt, tape, tuner and phono is 500mv-1volt) in real life a pre should have 3x-4x gain. This is my take. By the way 12B4A gain after insertion and other losses will be max 5x. My DHT pre with 3a5 battery tube in para-feed config has 3x gain. It is perfect for my CD player (heavily modified with 1.3 volt output) as well my phono and tuner.
My main system is heavily modified Fostex 206 in Fostex 208 back loaded horn cab driven with home made two stage AC coupled 300b se amp. My next project is 12'' high effc. cone driver in 60L sealed cab and 2'' comp driver in 300Hz tractrix front horn. Both the bass cabs and front horns are already constructed. I will install the drivers soon. The bass cabs I will drive with 50watt-100watt solid state amp and the 300hz horns will be driven with DC coupled el84/6V6 or 2A3 amp.
Again, congratulation!
12B4 Preamp wanted
Pls. check the link the resistor loaded 12b4A is simple to implement. If your B+ is 190 volt you need 5K 10watt resistor.
Pls follow the above schematic as mentioned in post no. 5, once it is up and running you can mod it afterwards for better sound etc. Please note I don't like sound signature that CCS loaded plates produces. But that is my preference you may like otherwise that is perfectly alright.
Regards
Pls. check the link the resistor loaded 12b4A is simple to implement. If your B+ is 190 volt you need 5K 10watt resistor.
Pls follow the above schematic as mentioned in post no. 5, once it is up and running you can mod it afterwards for better sound etc. Please note I don't like sound signature that CCS loaded plates produces. But that is my preference you may like otherwise that is perfectly alright.
Regards
So I connected the other earth that I had forgotten, one from the negative input of the rectifier, and it doesn't work anymore. The choke gets very hot so then I rewired the power supply but still the same thing happens with no sound.
I've had enough minhaj, sorry you invested your time with me. I'm not worthy and I don't want to do this any more.
The circuit I was using by the way does not have a 33uF cap. It was a simplified version roughly scrawled by Eli and I don't think it's a good one.
However I am not in a position to judge but these schematics didn't include the way the 10M45 was hooked up so maybe I screwed that as well.
In any case my play time with this preamp is over so it will go back to be forgotten in the cupboard as I have too many other things to do.
All the best,
Cheers
I've had enough minhaj, sorry you invested your time with me. I'm not worthy and I don't want to do this any more.
The circuit I was using by the way does not have a 33uF cap. It was a simplified version roughly scrawled by Eli and I don't think it's a good one.
However I am not in a position to judge but these schematics didn't include the way the 10M45 was hooked up so maybe I screwed that as well.
In any case my play time with this preamp is over so it will go back to be forgotten in the cupboard as I have too many other things to do.
All the best,
Cheers
All the best Wot.
Should you need my help some other day Please don't forget to knock my door.
Regards
Should you need my help some other day Please don't forget to knock my door.
Regards
Dear Wot,
I will give you very simple and complete schematic for 12b4 pre. Since you have all the necessary parts and you are only a inch away from completion you may like to try once again in the coming weekend.
I am confident that you are worthy for this.
Regards
I will give you very simple and complete schematic for 12b4 pre. Since you have all the necessary parts and you are only a inch away from completion you may like to try once again in the coming weekend.
I am confident that you are worthy for this.
Regards