Tube Amp Archive

andresound wrote: ↑Fri Mar 23, 2018 6:18 am I don’t speak that language (French?).

Spanish!

that was an amp i modded for a friend of mine.
the unnused triode make it easy.

Hi Guys, I am using this JTM45 type pre section in a bassman re-build. 2 ch (JTM and Dumble clean). Is the coupling cap circled in red, really necessary? Thanks That's funny... i "draw" that schematic maybe 10 years ago using Windows Paint. I'm not a pro now, but back those days i barelly understan...

I have the same amp. Is called the "Crestline" model.

I attached the schematic.

I have that DAW. It works with Linux. Similar to Ableton.

https://www.bitwig.com/en/bitwig-studio/overview.html

Man, you are lucky. Put voltages in a amp old like that without check works is really dangerous!!!

Before put yours hands in a guy like that i recommend you read a lot in forums like that or books.

Give us a bit more information about the amp. Model, gut pics,....

Sure you can, but you are gonna need another gain stage to raise uo the signal.

Here are some others examples of G2 regulation. Those ones use an EL34 and half ecc83 to do the job.

http://mundomusicalmeria.com/mundomusic ... n_2500.jpg

http://mundomusicalmeria.com/mundomusic ... 000_vr.jpg

Just for share proposits, years ago i repaired an old spanish tube amp with a voltage divider for G2:

http://s101.photobucket.com/albums/m74/ ... IGINAL.gif

Hi there, I have a 90´s Orange Overdrive with high frecuency noises. In fact i can recognice two diferent noises. One continious and the other is more like... "phone interferences". The strange is that both disapear with bias pot at minimun... Reverse diode is ok. ¿should i suspect from the bias fil...

i found my self..

138639

138 = Stancor (Chicago-Standard)

39 week / 1956 (could be 1966, but those caps seems older)

Power Trafo is marked:

12518-5
138639

Any idea where it cames?

New measurements.

Vin: 220vac
Vout: 3,98

220/3,98 = 55,274

so: 55,274 sqared = 3055 ohm
Voltages between primary extreme and CT: 119v - 101v

Some pics:
https://picasaweb.google.com/davidageit ... gvb5gvOzag

Repeat the measurement with 4R load on secondary side. If you're using a variac to excite the primary winding than by all means go to 200V or higher range. This will give results closer to the conditions in normal use. A second test to do is to determine ratio from each half of the primary to secon...

Hi, i have an old chasis with two 6V6, one 5Y3 and one 12AX7. No marked speaker impedance, so.. I aplied 36,2 vAC to primary/plate taps. I get 0,65 vAC in secondary. so: 36,2/0,65 = 55,6923 55,6923 square = 3101 ohms If a pair of 6V6 at 285vdc need to "see" 8k, i have a dilema: With a 2 ohm load i g...

From pin 8 there goes a wire to the first elko. (b+)

What DC voltage do you have there?