Hello everybody! I'm new to this forum and kinda new to vacuum tubes(2 years plus or minus) and any advice would be appreciated. I want to build from scratch the audio section of a Sonora model 220 to play music from an Mp3 player at work. I have all the parts(2x6sq7, 2x25L6gt, output transformer and 120 volt isolation transformer along with all the caps and resistors). My question is this: aside from not building any of the RF stuff before the first 6sq7 are there any other things to watch out for that might interfere with the sound, and, is there anything I can do to improve the fidelity a bit? Thanx in advance for the help. By the way I tried audioasylum and, to put it mildly, the reaction I got made it plain that my project isn't up to their megabucks audiofile standards! What I'm looking for is an inexpensive push-pull style amp to give my music that old-style sound from the good old days.

Isaac, interesting project. Be sure to post your results!

I haven't studied the 220 scheme and know nothing about MP3 players, but you probably should check out the signal level of the MP3 and see if a pre-amp might be req'd.

Somebody here will know more than I.

Doug,
I'm not familar with MP3 players, but suspect it has an earphone output jack only rated at several milliwatts and a low impedance. On the other hand a line level output of 600 ohms,if available, would be more appropriate for this application.

marv

:Isaac, interesting project. Be sure to post your results!
:
:I haven't studied the 220 scheme and know nothing about MP3 players, but you probably should check out the signal level of the MP3 and see if a pre-amp might be req'd.
:
:Somebody here will know more than I.

:Hello everybody! I'm new to this forum and kinda new to vacuum tubes(2 years plus or minus) and any advice would be appreciated. I want to build from scratch the audio section of a Sonora model 220 to play music from an Mp3 player at work. I have all the parts(2x6sq7, 2x25L6gt, output transformer and 120 volt isolation transformer along with all the caps and resistors). My question is this: aside from not building any of the RF stuff before the first 6sq7 are there any other things to watch out for that might interfere with the sound, and, is there anything I can do to improve the fidelity a bit? Thanx in advance for the help. By the way I tried audioasylum and, to put it mildly, the reaction I got made it plain that my project isn't up to their megabucks audiofile standards! What I'm looking for is an inexpensive push-pull style amp to give my music that old-style sound from the good old days.

Isaac,

If you decide to do the project, you may want to consider using a couple of 50L6 tubes and a 12SQ7. The filament series resister would be smaller using these tubes.

Radiodoc

::Hello everybody! I'm new to this forum and kinda new to vacuum tubes(2 years plus or minus) and any advice would be appreciated. I want to build from scratch the audio section of a Sonora model 220 to play music from an Mp3 player at work. I have all the parts(2x6sq7, 2x25L6gt, output transformer and 120 volt isolation transformer along with all the caps and resistors). My question is this: aside from not building any of the RF stuff before the first 6sq7 are there any other things to watch out for that might interfere with the sound, and, is there anything I can do to improve the fidelity a bit? Thanx in advance for the help. By the way I tried audioasylum and, to put it mildly, the reaction I got made it plain that my project isn't up to their megabucks audiofile standards! What I'm looking for is an inexpensive push-pull style amp to give my music that old-style sound from the good old days.
:
:Isaac,
:
:If you decide to do the project, you may want to consider using a couple of 50L6 tubes and a 12SQ7. The filament series resister would be smaller using these tubes.
:
:Radiodoc
:
By my math, the filament series resistor would go away entirely if you used Radiodoc's scheme, 2 X 12.6 + 2 X 50 = 124.2 volts.

Bill

:::Hello everybody! I'm new to this forum and kinda new to vacuum tubes(2 years plus or minus) and any advice would be appreciated. I want to build from scratch the audio section of a Sonora model 220 to play music from an Mp3 player at work. I have all the parts(2x6sq7, 2x25L6gt, output transformer and 120 volt isolation transformer along with all the caps and resistors). My question is this: aside from not building any of the RF stuff before the first 6sq7 are there any other things to watch out for that might interfere with the sound, and, is there anything I can do to improve the fidelity a bit? Thanx in advance for the help. By the way I tried audioasylum and, to put it mildly, the reaction I got made it plain that my project isn't up to their megabucks audiofile standards! What I'm looking for is an inexpensive push-pull style amp to give my music that old-style sound from the good old days.
::
::Isaac,
::
::If you decide to do the project, you may want to consider using a couple of 50L6 tubes and a 12SQ7. The filament series resister would be smaller using these tubes.
::
::Radiodoc
::
:By my math, the filament series resistor would go away entirely if you used Radiodoc's scheme, 2 X 12.6 + 2 X 50 = 124.2 volts.
:
:Bill

Thanks Bill,

I failed to see the 2x in front of the 6SQ7. The eyes are another thing to go with age.

Radiodoc

::::Hello everybody! I'm new to this forum and kinda new to vacuum tubes(2 years plus or minus) and any advice would be appreciated. I want to build from scratch the audio section of a Sonora model 220 to play music from an Mp3 player at work. I have all the parts(2x6sq7, 2x25L6gt, output transformer and 120 volt isolation transformer along with all the caps and resistors). My question is this: aside from not building any of the RF stuff before the first 6sq7 are there any other things to watch out for that might interfere with the sound, and, is there anything I can do to improve the fidelity a bit? Thanx in advance for the help. By the way I tried audioasylum and, to put it mildly, the reaction I got made it plain that my project isn't up to their megabucks audiofile standards! What I'm looking for is an inexpensive push-pull style amp to give my music that old-style sound from the good old days.
:::
:::Isaac,
:::
:::If you decide to do the project, you may want to consider using a couple of 50L6 tubes and a 12SQ7. The filament series resister would be smaller using these tubes.
:::
:::Radiodoc
:::
::By my math, the filament series resistor would go away entirely if you used Radiodoc's scheme, 2 X 12.6 + 2 X 50 = 124.2 volts.
::
::Bill
:
:Thanks Bill,
:
:I failed to see the 2x in front of the 6SQ7. The eyes are another thing to go with age.
:
:Radiodoc
:
Doing the math with the 6SQ7's and 25L6GT's we get a filament resistor of 181 ohms 16.2 watts, minimum. This will throw some serious heat. Can you trade in your tubes?

Bill

:::::Hello everybody! I'm new to this forum and kinda new to vacuum tubes(2 years plus or minus) and any advice would be appreciated. I want to build from scratch the audio section of a Sonora model 220 to play music from an Mp3 player at work. I have all the parts(2x6sq7, 2x25L6gt, output transformer and 120 volt isolation transformer along with all the caps and resistors). My question is this: aside from not building any of the RF stuff before the first 6sq7 are there any other things to watch out for that might interfere with the sound, and, is there anything I can do to improve the fidelity a bit? Thanx in advance for the help. By the way I tried audioasylum and, to put it mildly, the reaction I got made it plain that my project isn't up to their megabucks audiofile standards! What I'm looking for is an inexpensive push-pull style amp to give my music that old-style sound from the good old days.
::::
::::Isaac,
::::
::::If you decide to do the project, you may want to consider using a couple of 50L6 tubes and a 12SQ7. The filament series resister would be smaller using these tubes.
::::
::::Radiodoc
::::
:::By my math, the filament series resistor would go away entirely if you used Radiodoc's scheme, 2 X 12.6 + 2 X 50 = 124.2 volts.
:::
:::Bill
::
::Thanks Bill,
::
::I failed to see the 2x in front of the 6SQ7. The eyes are another thing to go with age.
::
::Radiodoc
::
:Doing the math with the 6SQ7's and 25L6GT's we get a filament resistor of 181 ohms 16.2 watts, minimum. This will throw some serious heat. Can you trade in your tubes?
:
:Bill

Bill,

Isaac may take a look at an amp using 60FX5 tubes at

http://www.heggeseth.com/60fx5_files/60fx5_amp.pdf

It is a mono amp, could multiply it by two for stereo. I think the tubes are still reasonably priced. There also,is a schematic for a stereo amp in the RCA receiving tube manual number RC-30.

Radiodoc

::::::Hello everybody! I'm new to this forum and kinda new to vacuum tubes(2 years plus or minus) and any advice would be appreciated. I want to build from scratch the audio section of a Sonora model 220 to play music from an Mp3 player at work. I have all the parts(2x6sq7, 2x25L6gt, output transformer and 120 volt isolation transformer along with all the caps and resistors). My question is this: aside from not building any of the RF stuff before the first 6sq7 are there any other things to watch out for that might interfere with the sound, and, is there anything I can do to improve the fidelity a bit? Thanx in advance for the help. By the way I tried audioasylum and, to put it mildly, the reaction I got made it plain that my project isn't up to their megabucks audiofile standards! What I'm looking for is an inexpensive push-pull style amp to give my music that old-style sound from the good old days.
:::::
:::::Isaac,
:::::
:::::If you decide to do the project, you may want to consider using a couple of 50L6 tubes and a 12SQ7. The filament series resister would be smaller using these tubes.
:::::
:::::Radiodoc
:::::
::::By my math, the filament series resistor would go away entirely if you used Radiodoc's scheme, 2 X 12.6 + 2 X 50 = 124.2 volts.
::::
::::Bill
:::
:::Thanks Bill,
:::
:::I failed to see the 2x in front of the 6SQ7. The eyes are another thing to go with age.
:::
:::Radiodoc
:::
::Doing the math with the 6SQ7's and 25L6GT's we get a filament resistor of 181 ohms 16.2 watts, minimum. This will throw some serious heat. Can you trade in your tubes?
::
::Bill
:
:Bill,
:
:Isaac may take a look at an amp using 60FX5 tubes at
:
:http://www.heggeseth.com/60fx5_files/60fx5_amp.pdf
:
:It is a mono amp, could multiply it by two for stereo. I think the tubes are still reasonably priced. There also,is a schematic for a stereo amp in the RCA receiving tube manual number RC-30.
:
:Radiodoc
:

:::::::Hello everybody! I'm new to this forum and kinda new to vacuum tubes(2 years plus or minus) and any advice would be appreciated. I want to build from scratch the audio section of a Sonora model 220 to play music from an Mp3 player at work. I have all the parts(2x6sq7, 2x25L6gt, output transformer and 120 volt isolation transformer along with all the caps and resistors). My question is this: aside from not building any of the RF stuff before the first 6sq7 are there any other things to watch out for that might interfere with the sound, and, is there anything I can do to improve the fidelity a bit? Thanx in advance for the help. By the way I tried audioasylum and, to put it mildly, the reaction I got made it plain that my project isn't up to their megabucks audiofile standards! What I'm looking for is an inexpensive push-pull style amp to give my music that old-style sound from the good old days.
::::::
::::::Isaac,
::::::
::::::If you decide to do the project, you may want to consider using a couple of 50L6 tubes and a 12SQ7. The filament series resister would be smaller using these tubes.
::::::
::::::Radiodoc
::::::
:::::By my math, the filament series resistor would go away entirely if you used Radiodoc's scheme, 2 X 12.6 + 2 X 50 = 124.2 volts.
:::::
:::::Bill
::::
::::Thanks Bill,
::::
::::I failed to see the 2x in front of the 6SQ7. The eyes are another thing to go with age.
::::
::::Radiodoc
::::
:::Doing the math with the 6SQ7's and 25L6GT's we get a filament resistor of 181 ohms 16.2 watts, minimum. This will throw some serious heat. Can you trade in your tubes?
:::
:::Bill
::
::Bill,
::
::Isaac may take a look at an amp using 60FX5 tubes at
::
::http://www.heggeseth.com/60fx5_files/60fx5_amp.pdf
::
::It is a mono amp, could multiply it by two for stereo. I think the tubes are still reasonably priced. There also,is a schematic for a stereo amp in the RCA receiving tube manual number RC-30.
::
::Radiodoc
::Thanks for all the input guys(why aren't there ever any gals in tube forums??). You're right about the dropping resistor, that's a lot of wasted heat circulating inside the cabinet. Maybe if I'll stick in a 25Z6gt rectifier for the B+ I can lower the resistor and wasted wattage(approx. 90 ohms and 8 watts if my calcs are correct).

::::::::Hello everybody! I'm new to this forum and kinda new to vacuum tubes(2 years plus or minus) and any advice would be appreciated. I want to build from scratch the audio section of a Sonora model 220 to play music from an Mp3 player at work. I have all the parts(2x6sq7, 2x25L6gt, output transformer and 120 volt isolation transformer along with all the caps and resistors). My question is this: aside from not building any of the RF stuff before the first 6sq7 are there any other things to watch out for that might interfere with the sound, and, is there anything I can do to improve the fidelity a bit? Thanx in advance for the help. By the way I tried audioasylum and, to put it mildly, the reaction I got made it plain that my project isn't up to their megabucks audiofile standards! What I'm looking for is an inexpensive push-pull style amp to give my music that old-style sound from the good old days.
:::::::
:::::::Isaac,
:::::::
:::::::If you decide to do the project, you may want to consider using a couple of 50L6 tubes and a 12SQ7. The filament series resister would be smaller using these tubes.
:::::::
:::::::Radiodoc
:::::::
::::::By my math, the filament series resistor would go away entirely if you used Radiodoc's scheme, 2 X 12.6 + 2 X 50 = 124.2 volts.
::::::
::::::Bill
:::::
:::::Thanks Bill,
:::::
:::::I failed to see the 2x in front of the 6SQ7. The eyes are another thing to go with age.
:::::
:::::Radiodoc
:::::
::::Doing the math with the 6SQ7's and 25L6GT's we get a filament resistor of 181 ohms 16.2 watts, minimum. This will throw some serious heat. Can you trade in your tubes?
::::
::::Bill
:::
:::Bill,
:::
:::Isaac may take a look at an amp using 60FX5 tubes at
:::
:::http://www.heggeseth.com/60fx5_files/60fx5_amp.pdf
:::
:::It is a mono amp, could multiply it by two for stereo. I think the tubes are still reasonably priced. There also,is a schematic for a stereo amp in the RCA receiving tube manual number RC-30.
:::
:::Radiodoc
:::Thanks for all the input guys(why aren't there ever any gals in tube forums??). You're right about the dropping resistor, that's a lot of wasted heat circulating inside the cabinet. Maybe if I'll stick in a 25Z6gt rectifier for the B+ I can lower the resistor and wasted wattage(approx. 90 ohms and 8 watts if my calcs are correct).

Isaac & Bill,

This may be the project to use the proverbial capacitor to drop the excess voltage in the filament circuit.

Radiodoc

:::::::::Hello everybody! I'm new to this forum and kinda new to vacuum tubes(2 years plus or minus) and any advice would be appreciated. I want to build from scratch the audio section of a Sonora model 220 to play music from an Mp3 player at work. I have all the parts(2x6sq7, 2x25L6gt, output transformer and 120 volt isolation transformer along with all the caps and resistors). My question is this: aside from not building any of the RF stuff before the first 6sq7 are there any other things to watch out for that might interfere with the sound, and, is there anything I can do to improve the fidelity a bit? Thanx in advance for the help. By the way I tried audioasylum and, to put it mildly, the reaction I got made it plain that my project isn't up to their megabucks audiofile standards! What I'm looking for is an inexpensive push-pull style amp to give my music that old-style sound from the good old days.
::::::::
::::::::Isaac,
::::::::
::::::::If you decide to do the project, you may want to consider using a couple of 50L6 tubes and a 12SQ7. The filament series resister would be smaller using these tubes.
::::::::
::::::::Radiodoc
::::::::
:::::::By my math, the filament series resistor would go away entirely if you used Radiodoc's scheme, 2 X 12.6 + 2 X 50 = 124.2 volts.
:::::::
:::::::Bill
::::::
::::::Thanks Bill,
::::::
::::::I failed to see the 2x in front of the 6SQ7. The eyes are another thing to go with age.
::::::
::::::Radiodoc
::::::
:::::Doing the math with the 6SQ7's and 25L6GT's we get a filament resistor of 181 ohms 16.2 watts, minimum. This will throw some serious heat. Can you trade in your tubes?
:::::
:::::Bill
::::
::::Bill,
::::
::::Isaac may take a look at an amp using 60FX5 tubes at
::::
::::http://www.heggeseth.com/60fx5_files/60fx5_amp.pdf
::::
::::It is a mono amp, could multiply it by two for stereo. I think the tubes are still reasonably priced. There also,is a schematic for a stereo amp in the RCA receiving tube manual number RC-30.
::::
::::Radiodoc
::::Thanks for all the input guys(why aren't there ever any gals in tube forums??). You're right about the dropping resistor, that's a lot of wasted heat circulating inside the cabinet. Maybe if I'll stick in a 25Z6gt rectifier for the B+ I can lower the resistor and wasted wattage(approx. 90 ohms and 8 watts if my calcs are correct).
:
:Isaac & Bill,
:
:This may be the project to use the proverbial capacitor to drop the excess voltage in the filament circuit.
:
:Radiodoc
:

::::::::::Hello everybody! I'm new to this forum and kinda new to vacuum tubes(2 years plus or minus) and any advice would be appreciated. I want to build from scratch the audio section of a Sonora model 220 to play music from an Mp3 player at work. I have all the parts(2x6sq7, 2x25L6gt, output transformer and 120 volt isolation transformer along with all the caps and resistors). My question is this: aside from not building any of the RF stuff before the first 6sq7 are there any other things to watch out for that might interfere with the sound, and, is there anything I can do to improve the fidelity a bit? Thanx in advance for the help. By the way I tried audioasylum and, to put it mildly, the reaction I got made it plain that my project isn't up to their megabucks audiofile standards! What I'm looking for is an inexpensive push-pull style amp to give my music that old-style sound from the good old days.
:::::::::
:::::::::Isaac,
:::::::::
:::::::::If you decide to do the project, you may want to consider using a couple of 50L6 tubes and a 12SQ7. The filament series resister would be smaller using these tubes.
:::::::::
:::::::::Radiodoc
:::::::::
::::::::By my math, the filament series resistor would go away entirely if you used Radiodoc's scheme, 2 X 12.6 + 2 X 50 = 124.2 volts.
::::::::
::::::::Bill
:::::::
:::::::Thanks Bill,
:::::::
:::::::I failed to see the 2x in front of the 6SQ7. The eyes are another thing to go with age.
:::::::
:::::::Radiodoc
:::::::
::::::Doing the math with the 6SQ7's and 25L6GT's we get a filament resistor of 181 ohms 16.2 watts, minimum. This will throw some serious heat. Can you trade in your tubes?
::::::
::::::Bill
:::::
:::::Bill,
:::::
:::::Isaac may take a look at an amp using 60FX5 tubes at
:::::
:::::http://www.heggeseth.com/60fx5_files/60fx5_amp.pdf
:::::
:::::It is a mono amp, could multiply it by two for stereo. I think the tubes are still reasonably priced. There also,is a schematic for a stereo amp in the RCA receiving tube manual number RC-30.
:::::
:::::Radiodoc
:::::Thanks for all the input guys(why aren't there ever any gals in tube forums??). You're right about the dropping resistor, that's a lot of wasted heat circulating inside the cabinet. Maybe if I'll stick in a 25Z6gt rectifier for the B+ I can lower the resistor and wasted wattage(approx. 90 ohms and 8 watts if my calcs are correct).
::
::Isaac & Bill,
::
::This may be the project to use the proverbial capacitor to drop the excess voltage in the filament circuit.
::
::Radiodoc
::Well, after almost 2 months of experimenting I finally came up with the best of both worlds. I started with the basic circuit of a Westinghouse H-122 but instead of using 2x25L6gt and a 25Z6GT I wired 2 70L7GT's with their filaments in parallel and connected this duo in series with a 6SC7 for the phase splitter and second audio stage, and ahead of all this I added in series a 6AV6 for the first audio stage. I put in a two-way switch. This way when I want to listen to recorded music I route the signal just through the first triode of the 6SC7. If I want to play guitar I just flip the switch and the signal is first routed through the 6AV6 and then through the rest of the amp.