• TalkBass has been independent since 1998. Add your voice.
    Create a free account to reply to discussions, view embedded media, and browse with fewer display ads.
    Join free Log in
    Want zero display ads or expanded classifieds tools? Compare plans.

Stingray aftermarket 2 band pre

#341
i_got_a_mohawk said:
How do you mean testing? Or just that you actually played using it?

My multimeter seems to flake out with the 2M resistors, so it looks like I'm going to have to hope for the best with those :-\
Click to expand...

As far as testing, I usually do a current draw test at a much lower than rated voltage to see if there is any short circuits, then test the inputs and outputs for excessive DC before I plug it in to anything. You can do all that with a DMM (what I still call an 'ohm meter', I need to stop doing that ;)).

But after all that, I plugged it into a test harness I made and got to hear how it sounds and I'm loving it.



On a vast majority of DMM's after about 680 Kohms, you need to test them with lead clamps (aka Invalid Link Removed) (you can make them for free if you have a set of old leads that fit your meter and some alligator clips to solder to the probe ends of them) and not touch either lead with your fingers (you can also just use a glass table or something and just press down against it with the DMM leads).. This is critical if you have one of those dreaded auto-ranging meters..

Your skin's resistance will mess with the readings if you're holding both ends (try it: grab both leads and the harder you squeeze the lower the resistance will show on the meter. This is especially true if you're sweating or your fingers are a little moist.). Also be sure to count out 3 - 5 seconds for the reading to stabilize.
 
#343
If you're going to start playing around with stuff like this on a regular basis, I highly recommend a really good DMM. I've been using a [Invalid or Expired Link Removed] and I love it. You can find them at a few places online still. I'm not ready to try the 2706B, but I'm sure its a superb meter as well. If I get a new one it will probably be the 2707B.
 
#345
sorry, if I touch on things that have been already addressed...
just found this thread and being somewhat if a diy'er myself and own an EBMM, I am very intrigued.

One question I have is has anybody used another op amp. If you are trying to capture that vintage stingray tone the LM4250 is the way to go, but has anybody experimented with another type? JFET input op amps are ideal for this application. There are some very nice offerings from Analog Devices that could be interesting to listen to.
 
#347
I threw a 741 in an early build of the board just to check everything was functional while waiting for the 4250s to arrive. It worked, but wasn't particularly amazing. Maybe as much down to input impedance as anything else, but I didn't bother investigating, I just wanted to see some sort of output on the scope.
 
#348
BassLife77 said:
I wouldn't trust that schematic. as you can see the capacitors on the schematic don't match up with the ones on the layout
Click to expand...

this reply is a little late but I wouldn't be too concerned with the value of the 1uF electrolytic caps. "1uF" may have been put on the schematic as more of a place-holder.
2 of them filter the power rail for the bias voltage. You can increase the value for improved filtering and decrease noise. At some point though you reach the point of diminishing returns.
The caps in the signal path are intended to block DC so that only ac signal enters and leaves the preamp. They will have an impact on low-frequency response depending on the value of resistance that follows. Increasing the value of the cap will lessen the audible impact on low frequencies, but again at some point you reach a point of diminishing returns.
 
#349
Totaly blown away but what you guys are building; all looks 1st class and suspect they will sound the same when they are sorted.

Anybody thinking of selling this super clean build version complete with pots and ready to solder in?
 
#350
Jim C said:
Totaly blown away but what you guys are building; all looks 1st class and suspect they will sound the same when they are sorted.

Anybody thinking of selling this super clean build version complete with pots and ready to solder in?
Click to expand...

I wouldn't have time to start assembling these on a commercial basis right now, but if someone else is interested PM me and we can talk quantity supply of boards.
 
#351
rumblinbass said:
this reply is a little late but I wouldn't be too concerned with the value of the 1uF electrolytic caps. "1uF" may have been put on the schematic as more of a place-holder.
2 of them filter the power rail for the bias voltage. You can increase the value for improved filtering and decrease noise. At some point though you reach the point of diminishing returns.
The caps in the signal path are intended to block DC so that only ac signal enters and leaves the preamp. They will have an impact on low-frequency response depending on the value of resistance that follows. Increasing the value of the cap will lessen the audible impact on low frequencies, but again at some point you reach a point of diminishing returns.
Click to expand...

A few posts further on it was said that the schematic was wrong in that part, the layout is right.
 
#359
I'm guessing a few posts got deleted or am I going crazy?

Here is what I have to say from what I can put together:
1. There is no excuse for the soldering job on the ebay one. I did better when I was literally 7 years old.
2. UncleFluffy is not selling these boards outright for profit. He just decided to do us ALL a favor here, and we bought him a beer for it.
3. Some people shouldn't be allowed on the internet because for some strange reason the ones that should be standing out in the cold trying to bribe the doorman always end up ruining quality online forums..
 

Latest posts

Top Bottom
Back