Author Topic: Re-wire stereo jack (Read 559 times)

worldfamousandy · « **on:** May 16, 2005, 08:14:35 AM »

I have a '76 Series 1 that I have always played with my blue box. Recently, I have been taking some advantage of the 1/4 output on the bass, and running batteries. I wish I could get both pickups this way. Anyone know what it takes to combine those pickup signals to a mono 1/4 jack?

effclef · « **Reply #1 on:** May 16, 2005, 08:20:10 AM »

Get a 1/4 stereo plug to 1/4 mono jack adapter.

Radio Shack part # 274-1520.

www.radioshack.com

bsee · « **Reply #2 on:** May 16, 2005, 09:22:30 AM »

Or order up a stereo-to-mono cable. I wouldn't think adding Radio Shack adapters would do much for your signal quality.

effclef · « **Reply #3 on:** May 16, 2005, 09:47:14 AM »

I would bet the adapter is molded as one assembly, which may actually be better for the signal path!

But you could also just rewire the jack. Move the wire from the ring conductor to the tip conductor and that should do it. (WorldFamousAndy may not know how to solder...)

EffClef

worldfamousandy · « **Reply #4 on:** May 16, 2005, 10:12:07 AM »

I do solder, and I thought about that solution. Is it really that simple?

effclef · « **Reply #5 on:** May 16, 2005, 10:24:04 AM »

Email valentino@alembic.com, and ask. They may want you to put series resistors in there to keep each output isolated, or something.

But it's my guess!

Also, Alembic may use connectors on their output jacks such that you can order a mono jack and just unplug the old one from the circuit board, and mount the new one, and plug it in.

EffClef

bsee · « **Reply #6 on:** May 16, 2005, 11:13:08 AM »

Anyone with a bass with Anniversary electronics has a stereo/mono toggle switch. They should be able to tell you if there's anything across the outputs when they are summed. I do remember hearing that a stereo/mono switch can be backfitted if desired.

With regard to an adapter, I was saying that going from the output to an adapter to a cable to an amp wouldn't be as clean as going from the output straight through a high quality cable to the amp. An extra connection can never help, right.

Also, the adaptor would have to be plugged directly into the jack of the bass. That would make the plug stick out further and have more leverage to break the jack or crack the top should it get bumped on something.

(Message edited by bsee on May 16, 2005)

worldfamousandy · « **Reply #7 on:** May 16, 2005, 12:51:49 PM »

That's why I didn't want to use an adaptor (chance of breakage).

I talked to Valentino today, and he said he'd mail me instructions for summing those signals. Apparently, it's not hard, but it is more than simply soldering them both to the tip.

dfung60 · « **Reply #8 on:** May 17, 2005, 01:09:39 PM »

To do a mono mod on your old Series bass, you do need to have two series resistors to get things to sum properly. Without them, you won't get any output unless both pickups are turned up fully. You want to have a 20Kohm resistor in line with the preamp/EQ output from each pickup, then connect them together to the tip connection at the output jack. The resistor value only needs to be approximate, but this is what was in my DS-5 power supply (you can check your to see what you need).

I wanted a mono out to use my bass with a wireless transmitter. It turned out the easiest way for me to do that was to make a 6 adapter cable with a stereo 1/4 that plugged into the bass, then I added the resistors inline in the cable, the added a mono 1/4 jack on the other end that I plugged the wireless into. Worked great, but as you may already be aware, the 5-pin XLR cable is providing power to the onboard electronics. The Alembic Series preamp is optimized for sound and expects external power, so it will eat a pair of 9v batteries in about 40 hours vs. 1000+ hrs of use for something like EMGs.

The output jack in the bass is a very complicated multiconductor/multi-switch setup, so I was interested in minimizing the changes in the bass. Of course, I could lose the adapter more easily than if it was built inside. Newer Series basses (must have changed around 1990) normally have mono output on the 1/4 jack, so you can get the proper connector and wiring instructions from Alembic.

The little resistors you need are cheap (I wouldn't buy an audio adapter at Radio Shack, but resistors will be OK) probably no more than $10 to build a little stereo->mono cable like mine. In your DS5, Alembic used fairly fancy RCA 5% resistors, but the only part that's critical is that the two resistors be relatively close in value (e.g., you don't need to buy those laser-trimmed Vishay resistors, even though this seems like a good excuse to).

David Fung

worldfamousandy · « **Reply #9 on:** May 18, 2005, 05:48:04 AM »

How did the wireless work out for you? That's part of the reason I am going to do this, along with the convenience of being able to go to small rehearsals and gigs without having to take my pedal board apart. Also, AC outlets are not always in abundance, so that power supply can really be a pain. Most of the time, I simply play through with one pickup. It works fine, but it bothers me not to have my sound.

dfung60 · « **Reply #10 on:** May 18, 2005, 04:42:49 PM »

The wireless hook up worked fine. There were only two gotchas. The first I mentioned before - the 9v battery life was very short. The second one was pretty minor - I had to reduce the output level pots a bit to prevent overdriving the wireless transmitter which had less headroom than a regular amp.

The regular 18' 5-pin cable is a LOT shorter than I like (I don't run around much, but I guess I don't want to stand so close to my amp either). I have 4 Series basses and when I had the 3rd one built I had them build the cable a bit longer (25' or so). That's better, but the wireless is better still.

David Fung

gblick · « **Reply #11 on:** May 20, 2005, 02:24:12 PM »

Another thing you could do is replace the mono plug on whatever cable you want to use with a stereo plug, with the wire going to both the tip and ring of the new stereo plug.

gblick · « **Reply #12 on:** May 20, 2005, 02:39:15 PM »

When I wrote that up above, I didn't know you needed resistors in there. If that's the case, you might be able to get some very small resisitors in the plug (but maybe not).

worldfamousandy · « **Reply #13 on:** May 23, 2005, 11:09:29 PM »

Thanks for the advice. I got the instructions/drawing for the conversion from stereo to mono in the mail today, and I I performed the operation with relative ease. It is not hard. If it were, I probably would not have been able to do it! Dave, it appears that I did the same thing you did, except I did it inside the bass. I used a pair of 22k, 1/4 watt resistors from Radio Shack, and summed the wires to the tip connection of the jack. I would not have figured it out on my own (or I would not have been 100% confident I had figured it out), so the instructions were important to me. A little solder and heat shrink later, and I was in business!

The funny thing is, I had the opportunity to have Alembic rebuild this for me a few years ago, while bass was back at the factory for a major neck/headstock repair. Right before they sent it back, they called and asked if wanted to have that jack re-wired for mono output. I thought it would be best to leave it original, even though it was of no use to me. Dumb move on my part.
I bought this bass used when I was 19 (17 years ago), entirely because of its sound and playability. Since then, I have become aware of Alembic's rich history, along the prestige associated with owning one. While I am proud of my bass, I also would never dream of letting it sit idle as a mere collectors item. I gig with this bass, and I will gig with it forever! I don't think I could ever get used to another bass. With my new mono configuration, it is simply a little more useful to me.

David Houck · « **Reply #14 on:** May 24, 2005, 10:54:18 AM »

Congrats on a successful operation!