• 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.

Active preamp, no EQ

#141
SGD Lutherie said:
The first time I put a JFET buffer into a bass (my '73 Rick with Hi-A pickups), I installed a bypass switch. I never used it in passive because it sounded so lifeless! The buffer extended the top end and tightened up the bottom.
Click to expand...

I have been talking to the guys who make the Redeemer about a buffer that could preserve Ric-O-Sound, which you probably remember from owning a Ric is a way of keeping the pickups isolated until you plug into the mono jack. They have a good idea but the R&D makes it a bit cost prohibitive for me. Essentially this module would come with two jacks instead of one, two pickup inputs instead of one, and a selector switch in addition to the battery clips. Do you think you could design anything similar or suggest any schematics for DIY? (I know how to solder...)

My other idea was to keep ROS passive and just get a $50 module for mono but that requires some annoying "tricks" in the circuit to keep the signals from mixing prematurely.
 
#142
cassius987 said:
I have been talking to the guys who make the Redeemer about a buffer that could preserve Ric-O-Sound, which you probably remember from owning a Ric is a way of keeping the pickups isolated until you plug into the mono jack. They have a good idea but the R&D makes it a bit cost prohibitive for me. Essentially this module would come with two jacks instead of one, two pickup inputs instead of one, and a selector switch in addition to the battery clips. Do you think you could design anything similar or suggest any schematics for DIY? (I know how to solder...)

My other idea was to keep ROS passive and just get a $50 module for mono but that requires some annoying "tricks" in the circuit to keep the signals from mixing prematurely.
Click to expand...

By the time I had a buffer in my Ric is was no longer stereo. I had a series/parallel switch for the two pickups. Then it had three pickups (I added a DiMarzio Model P). It also had a Varitone, and I didn't feel like making a stereo version. First I had a Bartolini Hi-A TC-1 preamp, but the headroom was to low and it would clip. Then I installed the JFET circuit.

I still have the TC-1 I bought back in 1977!

The dual buffer I posted a photo of works this way. Each pickup has its own buffer, and then they are mixed together. That would be fairly simple to use for a stereo bass.

The wiring on the Redeemer is a bit odd from what I remember. I'd have to refresh my memory since I haven't looked at one in a while.
 
#143
rumblinbass said:
possible.
IMO the main purpose of an onboard preamp is to unload the pickups and provide a buffer so that you can get all that the pickups can offer.

that said, my dream bass would have no eq/tone control at all. Just a buffer and blend/balance and volume...maybe not even that.

Not quite sure of the passive master tone...have to give that some thought. AFAIK it really is just a low pass filter. Should be quite easy to implement in an active preamp but I would have to think about it.
Click to expand...

Linc Luthie
 
#144
SGD Lutherie said:
If you build the NTMB, I'd give it a little more gain. Those preamps are on the quiet side.

Be aware that some JFET buffer circuits; such as the Stratoblaster type; actually work better on 9v. You can change the components to make it work with 18v however, but they work great on 9v.
Click to expand...

David, thanks for the tips. Yes, when I chose the parts for my JFET buffer, it was obvious I'd have to retune it for 18V. Right now, I only plan to use it in my 9V frankenbass.

When are you going to start offering SGD preamps? I might just give up the DIY bug on this and buy one of yours.
 
#146
SGD Lutherie said:
The dual buffer I posted a photo of works this way. Each pickup has its own buffer, and then they are mixed together. That would be fairly simple to use for a stereo bass.
Click to expand...

Is that something I could do DIY if I had a schematic?

It's always good to have a guy like you around, who ALSO knows what a Ric is and does... makes these discussions go smoother for me.
 
#148
rumblinbass said:
would I? no, probably not. but then I would not buy this preamp. If I was to design a preamp with tone control I probably would add it then either. mainly because I like to keep the number of stages in the signal path to a minimum.
Click to expand...

No, what I was asking is if you have a preamp topology like that one; buffer -> tone controls; where would you like to see the volume control?
 
#149
cassius987 said:
Is that something I could do DIY if I had a schematic?

It's always good to have a guy like you around, who ALSO knows what a Ric is and does... makes these discussions go smoother for me.
Click to expand...

Here's a link to a schematic for a preamp that uses a JFET buffer for each pup before going into the amplifier stage. Note this doesn't support a blend knob option.

Invalid Link Removed

David, if your circuit has a buffer for each preamp but still supports a blend pot, can you post? Or at least begin selling them on your website?
 
#150
Rob22315 said:
When are you going to start offering SGD preamps?
Click to expand...

Hopefully I'll have them on the website soon, but I can make them anytime someone needs them. I used to make for the low-Z pickups I was making at the time. I just made a custom low-Z set of sidewinders and the preamp.

I have a few preamps in the works as well as the buffers.
 
#151
cassius987 said:
Is that something I could do DIY if I had a schematic?

It's always good to have a guy like you around, who ALSO knows what a Ric is and does... makes these discussions go smoother for me.
Click to expand...

I posted a schematic for the Alembic Stratoblaster earlier. My buffer is based on that. You can get circuit boards for that at GGG.
 
#152
SGD Lutherie said:
Hopefully I'll have them on the website soon, but I can make them anytime someone needs them. I used to make for the low-Z pickups I was making at the time. I just made a custom low-Z set of sidewinders and the preamp.

I have a few preamps in the works as well as the buffers.
Click to expand...

I'm interested. I'd like a 3 band 5 knob 18V preamp. I don't currently have switchable/sweepable mid but don't mind if it comes with. I don't need an active/passive switch. How much and what's included (need pots if they're different from what Ibanez uses, don't need a jack)? What tone frequencies are you using? I'm getting your neo pickups so something matched to those would be even better.
 
#154
SGD Lutherie said:
No, what I was asking is if you have a preamp topology like that one; buffer -> tone controls; where would you like to see the volume control?
Click to expand...

well, it is a volume control so probably leave it at the output of the tone control amp. not sure changing what works and what people expect is a necessarily a good thing.

the only potential issue I see is a gain stage (tone control boost) after the volume pot (attenuator).
 
#155
rumblinbass said:
well, it is a volume control so probably leave it at the output of the tone control amp. not sure changing what works and what people expect is a necessarily a good thing.

the only potential issue I see is a gain stage (tone control boost) after the volume pot (attenuator).
Click to expand...

I'd do Pickup Buffer & Blend Stage -- Active Tone Stage -- Volume & Final Buffer Stage? The last stage output would be direct from the last opamp. This would require at least 5 active devices unless the blend and volume functions were done passively. I don't see getting below 4 devices but four's reasonable if you get a quad chip. 2 pup buffers, 1 tone control, 1 output buffer. While I had fun doing the JFET buffer, I'd stick with opamps. IIRC, the one used by the NTMB has really low current draw (MC33178) and can be had from Mouser in a quad pack. Also, one of the OPA opamps was designed for low current draw audio applications but currently only comes in a quad package.
 
#156
sorry if this was already covered but I didn't have the time to read this entire thread. Why not just use EMG pick- ups? They have all the attributes mentioned built right into the pick- ups>
 
#157
Rob22315 said:
I'd do Pickup Buffer & Blend Stage -- Active Tone Stage -- Volume & Final Buffer Stage? The last stage output would be direct from the last opamp. This would require at least 5 active devices unless the blend and volume functions were done passively. I don't see getting below 4 devices but four's reasonable if you get a quad chip. 2 pup buffers, 1 tone control, 1 output buffer. While I had fun doing the JFET buffer, I'd stick with opamps. IIRC, the one used by the NTMB has really low current draw (MC33178) and can be had from Mouser in a quad pack. Also, one of the OPA opamps was designed for low current draw audio applications but currently only comes in a quad package.
Click to expand...

sounds good.
the great thing about DIY is that you can build exactly what you want.
 
#160
Rob22315 said:
This circuit looks like a great 3 band equalizer but I'd like to tweak the frequencies.

Link Removed

How are the three filter frequencies calculated from these components?
Click to expand...

I've seen that ckt before...
here's a link that goes thru the numbers that you need.

Elliott Sound Products is another website I frequent. There are a lot of audio circuits with really good explanations. Somewhere on that site I'm sure there is an explanation of the Active Baxandall Tone Ctrl Ckt.
 

Latest posts

Top Bottom
Back