Tube Amp with the "Good Kind of Distortion"

[SIY]

Thank for reply
I really don't know about the DC heater or property done AC,

Short version: they are interchangeable in 99.999% of situations.

 

[dienson]

Short version: they are interchangeable in 99.999% of situations.

SIY thank U

 

[Helicopter]

Hmmz. Surfing how to parallel tube amp output tubes and found a curve tracer assembled kit and vacuum tube tester.

Buy online

etracer digital vacuum tube curve tracer/tester project's website

www.essues.com

This is the way. Better and cheaper than vintage tracers. Unsurprisingly, lots of tube 'experts' swear by vintage gear that performs worse.

 

[Doodski]

This is the way. Better and cheaper than vintage tracers. Unsurprisingly, lots of tube 'experts' swear by vintage gear that performs worse.

Yes, and no CRT screenshots made with 35mm camera gear and a hood. It's pure PC based. For reaLZ!
Behold... A oscilloscope camera for a Tektronix O-scope.

 

[Helicopter]

Yes, and no CRT screenshots made with 35mm camera gear and a hood. It's pure PC based. For reaLZ!
Behold... A oscilloscope camera for a Tektronix O-scope.

Admittedly I am a little jealous of people who got to cherry pick gear from old lab cleanout day. I would love to play around with this stuff if some of it fell in my lap.

 

[Doodski]

Admittedly I am a little jealous of people who got to cherry pick gear from old lab cleanout day. I would love to play around with this stuff if some of it fell in my lap.

I've handled some of the Tektronix camera gear on 7000 series scopes for demonstration and getting a look at how it all looked and it's all beasty equipment. No pictures taken just assembled the gear and checked it out.

 

[MakeMineVinyl]

Yes, and no CRT screenshots made with 35mm camera gear and a hood. It's pure PC based. For reaLZ!
Behold... A oscilloscope camera for a Tektronix O-scope.

I think that was a polaroid camera back. I never actually used one but that's my memory.

 

[Doodski]

I think that was a polaroid camera back. I never actually used one but that's my memory.

Could be. I know very little about camera gear. To me it was big, chunky, metal.. arrgH heavy...

 

[egellings]

The amplifier will not be harmed by using either tube. Performance may vary.

 

[mhardy6647]

Hello all member
I am newbee, I need some help about my McIntosh C8 tube preamp, I want to buy new tubes for C8, but the stock tube have letter A at end of tube modelname ( 12AX7A ), and all tubes on market no letter A on it ( 12AX7 )
question is can I buy tube 12AX7 without letter A and use on C8 ?
Thank you all

The 12AX7A has a different filament configuration (spiral wound) to reduce noise and/or hum.

http://www.tubebooks.org/tubedata/HB-3/Receiving_Tubes_Part_2/12AX7-A.PDF

http://www.tubebooks.org/tubedata/HB-3/Receiving-Type_Industrial_Tubes/6681_12AX7.PDF

There are reports on the internet that the unsuffixed version can only be used with parallel filament circuits, while the "A" morph can be used with series or parallel filament circuits, but I am not at all sure that is true. That said, generally speaking*, the "A" suffix referred to a tube with a controlled heater warm up time, which is (more or less) required for series filament strings, and tubes like the 12AX7 were occasionally (OK, more than occasionally!) used in transformerless (!), so called "AC-DC" series string filament electronic equipment. Such designs were rightly known, even when they were common in consumer products, known as "killer" circuits. With a nonpolarized AC mains plug, there was a 50-50 chance of the chassis being "hot" (i.e., directly connected to the hot side of the AC supply).

The two spec sheets above from RCA's HB-3 reference are pretty much "Gospel".

______________________
* always remember: all generalizations are false, including this one.

 

[mhardy6647]

since I mentioned "Killer" transformerless circuit designs it seems only fair to illustrate one. Note the configuration of the power supply in this charming "spud"* stereo amplifier, using the redoubtable (not) 60FX5 tube. The two tubes' 60 volt filaments are in series with each other and the 120 VAC supply.

source: https://worldradiohistory.com/BOOKSHELF-ARH/RCA-Books/RCA-Receiving-Tube-Manual-1964-RC-23.pdf page 590

_________________
* In vacuum tube DIY parlance, a "spud amp" is one that uses a single vacuum tube (in this case, a single vacuum tube per channel) with no other active components (other than the HV rectifier diode). Thus, a "spud" amp is a "one tuber".

This is the other kind of spud/tuber, for those for whom English may not be a primary language:

 

[dienson]

The 12AX7A has a different filament configuration (spiral wound) to reduce noise and/or hum.

http://www.tubebooks.org/tubedata/HB-3/Receiving_Tubes_Part_2/12AX7-A.PDF

http://www.tubebooks.org/tubedata/HB-3/Receiving-Type_Industrial_Tubes/6681_12AX7.PDF

There are reports on the internet that the unsuffixed version can only be used with parallel filament circuits, while the "A" morph can be used with series or parallel filament circuits, but I am not at all sure that is true. That said, generally speaking*, the "A" suffix referred to a tube with a controlled heater warm up time, which is (more or less) required for series filament strings, and tubes like the 12AX7 were occasionally (OK, more than occasionally!) used in transformerless (!), so called "AC-DC" series string filament electronic equipment. Such designs were rightly known, even when they were common in consumer products, known as "killer" circuits. With a nonpolarized AC mains plug, there was a 50-50 chance of the chassis being "hot" (i.e., directly connected to the hot side of the AC supply).

The two spec sheets above from RCA's HB-3 reference are pretty much "Gospel".

______________________
* always remember: all generalizations are false, including this one.

mhardy6647: Thank you
I am not pro to understand what you wrote, thank you anyway
Just ask if anyone know can replace 12AX7 to 12AX7A ( stock tubes on McIntosh C8 Preampplifier ?
Thank bro Have a good weekend

 

[mhardy6647]

mhardy6647: Thank you
I am not pro to understand what you wrote, thank you anyway
Just ask if anyone know can replace 12AX7 to 12AX7A ( stock tubes on McIntosh C8 Preampplifier ?
Thank bro Have a good weekend

So... yes... assuming your Mac doesn't have a series filament string.
Which is a pretty darned safe assumption.

No good reason to do so, though. The "A" tubes should peform a little better in terms of S/N.
Do you have specific tubes in mind?

 

[MakeMineVinyl]

mhardy6647: Thank you
I am not pro to understand what you wrote, thank you anyway
Just ask if anyone know can replace 12AX7 to 12AX7A ( stock tubes on McIntosh C8 Preampplifier ?
Thank bro Have a good weekend

If in doubt, I'd just use the "A" spec ones.

 

[dienson]

So... yes... assuming your Mac doesn't have a series filament string.
Which is a pretty darned safe assumption.

No good reason to do so, though. The "A" tubes should peform a little better in terms of S/N.
Do you have specific tubes in mind?

I want to try this :

Genalex Gold Lion 12AX7 tube (ECC83),​

one month my amp kill one tubes, i am waiting to replace from bestbuy, now I don't want to use preamp, I know get tubes from Mac so slow, then want to buy another tubes use this waiting time,
one thing I try swap the dead tube around,
if swap the dead tube to V1 or V2 the sound on left or right off (no sound)
if swap the dead tube to V3 or V4 the sound light not warm, a little distort, but sound out left right okie
Thank you

 

[dienson]

If in doubt, I'd just use the "A" spec ones.

I try to looking around, don't see any store have 12AX7A, maybe it has different name

 

[MakeMineVinyl]

I try to looking around, don't see any store have 12AX7A, maybe it has different name

ECC83

 

[dienson]

ECC83

here the ones I want to buy, but it haven't letter"A"

Genalex Gold Lion 12AX7 tube (ECC83)​

 

[MakeMineVinyl]

here the ones I want to buy, but it haven't letter"A"

Genalex Gold Lion 12AX7 tube (ECC83)​

I'm sure they will be fine.

 

[dienson]

I'm sure they will be fine.

thank U
I'll place order two from Amazon,
and have another question, I'll buy two tubes, what socket I replace, on board it say V1, V2, V3, V4
thank U
Have a good night