Search found 284 matches

by FunkyE9th
Wed Jan 18, 2012 6:27 pm
Forum: Technical Discussion
Topic: Amp Question
Replies: 11
Views: 2497

Re: Amp Question

My guess.... Looks to me like they are trying to feedback part of the heater signal to cancel some 60Hz noise from the reverb. By making the one side have a variable cap, you can change the phase and amplitude of the 60Hz signal that's fed back.
by FunkyE9th
Tue Nov 01, 2011 8:09 pm
Forum: Technical Discussion
Topic: Any experience with Mojo Speakers?
Replies: 11
Views: 3167

Re: Any experience with Mojo Speakers?

I've never tried any of the mojo speakers, but I've been thinking of it. If you check out some of the Granger amp demos on youtube, they use mojo speakers.
by FunkyE9th
Fri Jul 15, 2011 1:46 pm
Forum: Technical Discussion
Topic: Chicago area wood source
Replies: 10
Views: 2525

Re: Chicago area wood source

Yeah Owl is a great place to go for wood. I've been to the Lombard and Des Plaines store. The Des Plaines store is their biggest store.

Another place that I just heard about is ... http://www.horiganufp.com/ I was actually there last week.
by FunkyE9th
Fri May 27, 2011 4:30 am
Forum: Trainwreck Discussion
Topic: Low Frequency Response
Replies: 14
Views: 4191

Re: Low Frequency Response

Attached is a file that shows you the math on how to calculate the 3dB point using the transfer function. It gives the same result as using Tau (i.e using the time constant formula)
by FunkyE9th
Fri May 20, 2011 8:54 pm
Forum: Trainwreck Discussion
Topic: Low Frequency Response
Replies: 14
Views: 4191

Re: Low Frequency Response

Thanks! Now I get it. I got the same plot as you did. My problem was when I did the math via 20log(vo/vin) it was relative to 0dB so I was getting ~810Hz. When really it should have been 3dB down from -1.96dB as you pointed out. It maxes out at -1.96dB because of the resistive divider so you'll neve...
by FunkyE9th
Fri May 20, 2011 3:14 pm
Forum: Trainwreck Discussion
Topic: Low Frequency Response
Replies: 14
Views: 4191

Re: Low Frequency Response

Using 20log(Vo/Vi) should have been the correct thing to do. You are dealing with voltages. 10log(P1/P2) is used if you are dealing with power. P already has the voltage squared that's why it's only multiplied by 10 instead of 20. Edited/corrected due to my wrong math.. :( Oops!!! Nevermind my volta...
by FunkyE9th
Sat May 14, 2011 9:28 pm
Forum: Technical Discussion
Topic: Negative feedback - How much?
Replies: 45
Views: 17832

Re: Negative feedback - How much?

As mentioned above, the LTP is a differential amplifier. It takes the difference (subtraction) between the 2 inputs and amplifies it. For example: Cosine(0) = 1: Cosine(180) = -1 This is 180degrees out phase with respect to cosine(0). Yes I already knew that. But my argument is about negative feedb...
by FunkyE9th
Sat May 14, 2011 2:04 pm
Forum: Technical Discussion
Topic: Negative feedback - How much?
Replies: 45
Views: 17832

Re: Negative feedback - How much?

no the long tailed pair is a differential amplifier. Page 177 of Merlin's 1st book. With due respect, this is not relevant to the point I am making. I'm talking about the phase between the NFB signal and the PI's cathode (being out-of-phase). (Not discussing the difference between the PI's plates -...
by FunkyE9th
Sat May 14, 2011 1:12 pm
Forum: Trainwreck Discussion
Topic: My X10 has begun
Replies: 190
Views: 43488

Re: My X10 has begun

If you really want to stick with 1K, another option is to piggy back 2 5W 2K resistor in parallel. You get the equivalent of a 1K 10W resistor. Edited to add... Just wanted to say that the simulation I provided was not meant simulate the Xits amps PS. The main point I was trying to make was that the...
by FunkyE9th
Sat May 14, 2011 4:36 am
Forum: Trainwreck Discussion
Topic: My X10 has begun
Replies: 190
Views: 43488

Re: My X10 has begun

Keeping this simple regarding the 1k 5W wattage rating. taking 12W as max dissipation and 330 volts on the plate: 12w/330v = 36mA draw screen = 10mA 3x12ax7 = 5mA This is 51mA 0.051 * 0.051 * 1000ohms = 2.6W so the 5W being double should be okay. I assume it is if Xits used them but just want to un...
by FunkyE9th
Fri May 13, 2011 7:58 pm
Forum: Technical Discussion
Topic: Switchcraft MILSPEC Phone Jack
Replies: 28
Views: 7034

Re: Switchcraft MILSPEC Phone Jack

Thanks guys. Looks like I have several options. Will also check mcmaster and Ace. Got a few of those Ace HW in the are so will probably check that out also. Got a lot of my screws and nuts over there.
by FunkyE9th
Fri May 13, 2011 6:07 pm
Forum: Technical Discussion
Topic: Switchcraft MILSPEC Phone Jack
Replies: 28
Views: 7034

Re: Switchcraft MILSPEC Phone Jack

Thanks, will put those down on my next mouser order.
by FunkyE9th
Fri May 13, 2011 3:21 pm
Forum: Technical Discussion
Topic: Switchcraft MILSPEC Phone Jack
Replies: 28
Views: 7034

Re: Switchcraft MILSPEC Phone Jack

David,

Do you use anything to isolate it from the chassis? Some kind of special washer? Been thinking of trying the jack out, but not if I can't isolate it.

Thanks!
by FunkyE9th
Tue May 10, 2011 10:26 pm
Forum: Technical Discussion
Topic: Amp prototyping
Replies: 22
Views: 6523

Re: Amp prototyping

I've been thinking of using these.. http://apexjr.com/images/coloredposts.JPG but haven't gotten around to it. It's a dollar a piece so it gets expensive quick. :(
by FunkyE9th
Tue May 10, 2011 9:19 pm
Forum: Technical Discussion
Topic: Quick Bleeder R, Safety Question
Replies: 5
Views: 1277

Re: Quick Bleeder R, Safety Question

Under no load conditions (this is your worst case i.e. voltage is maxed), with a full wave rectifier, your voltage is approx SQRT(2) times the rms voltage of your PT. If you have a 260-0-260 PT, you should get ~368VDC. So from there you can calculate current and power dissipated by your resistor. Ho...