JeffTD
Senhor Testiculo
Oh shit, totally forgot about that guide! Going to have to make a parts order and get cracking on this summabitch!
5150 Mod Thread
- Thread starter Wolfeman
- Start date
Oh shit, totally forgot about that guide! Going to have to make a parts order and get cracking on this summabitch!
Chris_P_Critter
Freeze Tag Assassin
Quick clip of how my amp now sounds at low MV. Using Ola's latest DI's(thanks). Wish I had a clip before I started fucking with it.
http://dl.dropbox.com/u/2033066/5150combomodtest.wav
Edit- Same amp settings/mic position, just cranked MV.... What a big difference.
http://dl.dropbox.com/u/2033066/5150combomodtestfullmv.wav
http://dl.dropbox.com/u/2033066/5150combomodtest.wav
Edit- Same amp settings/mic position, just cranked MV.... What a big difference.
http://dl.dropbox.com/u/2033066/5150combomodtestfullmv.wav
MaxStatic
Member
I can't really think of anything else to do to it now.... I don't want to change transformers or anything, not worth it in a $375 amp.
Mid sweep, bias, and changing the coupling caps to 5150 head values seems to have helped this amp out tremendously. If anyone has any other ideas, post em here!
Mid sweep, bias, and changing the coupling caps to 5150 head values seems to have helped this amp out tremendously. If anyone has any other ideas, post em here!
JeffTD
Senhor Testiculo
Uberkab
The 2x12 probably wouldn't sound half that bad with a set of V30's in it. Those Sheffield's sound ok in the room, but god damn awful mic'd up.
Wolfeman
I know this thread is old but could you post exactly how you did the mid sweep mod? If you can that would be amazing!
I know this thread is old but could you post exactly how you did the mid sweep mod? If you can that would be amazing!
ah shit that sucks! I hope everything goes good for him! Did anyone get the info on the mid sweep mod and try it out?
sprack
Thread Killer
I don't know exactly what resistor it was, and it depends on if it's a 5150, 5150 II, or the combo. I'll look at the schem tomorrow and let you know. Also, what I did was change the resistor value, then fed it to the pot. you can then play around with values of the resistor/pot to get the range and amount of sweep you want. If you leave the resistor out, which is fine to do, you just get a really wide range that IMO becomes unusable to a point. But either way is fine.
C_F_H_13
Protools Guru
Off topic question.
Anyone know of any good websites/pdfs/books/videos that would help someone understand the basics of amp design?
I'm not about to attempt to mod my 5150 myself, but it would be a cool hobby to at least get started on that stuff, and start understanding WTF is going on inside this beast.
Anyone know of any good websites/pdfs/books/videos that would help someone understand the basics of amp design?
I'm not about to attempt to mod my 5150 myself, but it would be a cool hobby to at least get started on that stuff, and start understanding WTF is going on inside this beast.
Start by reading the RCA Radiotron Designers Handbook. You should be able to find that free online. It's pretty much the book that laid out tube amp design for the years to come(I think it was written in the 1950's).
Also, read all you can on the AX84 site. They have some good tutorials on how amps work, piece by piece.
Also, read all you can on the AX84 site. They have some good tutorials on how amps work, piece by piece.
C_F_H_13
Protools Guru
Where would be the best spots for me to add (correct) bias test points for my 5150II? From what I could find out, pin 8 is where a bias probe checks the bias. I'm just not sure at which point to tie into to get a reading.
Pin 1 and 8 should be tied together, so anywhere off of there. You still need to add 1ohm resistors to ground, and read the bias across said resistor. You could use 2 (one for each pair of tubes) or use one for each tube if you wanna go that far.
I should add that you will have to cut traces on the pcb if you want to do it properly. If you don't want to go all out like that, you can just add one resistor and check the overall bias for all 4 tubes at once.
I should add that you will have to cut traces on the pcb if you want to do it properly. If you don't want to go all out like that, you can just add one resistor and check the overall bias for all 4 tubes at once.
Yeah, I couldn't see anyway to get a read from a single tube or pair without cutting a trace or jumper. If I wanted a read from each pair, where should I cut the traces?
So, just to clarify, I will have two 1 ohm resistors, one for each pair, with one end connected to the trace, and the other to ground. Just ground anywhere to the chassis? I would then run a wire from the ground to the back of the amp as the common ground test point. After that, run a wire from the leg of the resistor that connects to the trace to the back of the amp as a test point to measure that pair. Am I right? Thanks for all the help Wolfeman!
