Installing the mono/stereo switch

[goran]

Thanks Mica, yea I downloaded the PDF from FAQ page, and also told him about resistors.
The usually repairs guitars electronics, but this was first time he saw an Alembic, he was intimidated. He's was like: "Man who ever build this bass, that guy is special..." and the like a kid told me what's in in language that I don't understand( electronics language).

He also opened the DS-5 and said that it needs to change some stuff that were not changed for years, and will try to work on that hum that I had when I unplug the bass from DS-5.

Anyway, I'll see how it will be... everybody says guy is great in those things.

[JimmyJ]

Wow, I've learned yet another thing from Mica.  Who knew these basses came with a built in "more me" feature?  Ha!

Goran, you say "...will try to work on that hum that I had when I unplug the bass from DS-5."  Despite what I said above about being able to silently unplug the 5-pin cable at the bass (with the pickup selector set to "off") it's possible that will result in some hum from the amp because it leaves a long "un-terminated" cable connected to the input.  In an effort to keep extra noise at a minimum I've built a mute switch into my studio DI which shorts the input before I unplug anything.  I've also modified one DS5 to run two mono outputs with a mute switch on one of them. 

Glad you found a guy to help with the soldering.  And we love it that he got excited by the internal artwork.  That should inspire him to do a good job.

Jimmy J

[goran]

Hey guys...

So he did it, bass works with batteries, but since someone left batteries inside (long time ago), I need to change those little battery plugs, so it works but contact is breaking up.
The guy did amazing work, I'll let you know everything that he did on my bass!

Just going tomorrow to him to change those small plugs, he even did something to DS-5.

But all that tomorrow.

g

[goran]

Hey guys sorry it took so long, but here is an update:

Bass works on batteries and has a mono switch, which is great if I have to just take a bass for jamm session or small gigs. But, I'll still use the DS5 for big venues.


So guy did the amazing work, he even changed the capacitors (I think that's the name, those two blue things inside DS-5), tested and cleaned it.

So what he did also was this, he changed those, I think preamp modules, there is five of them, so inside are new ones, and outside are old ones.
He measured them and said that I will get 3 times more battery life than on old ones, and that sound shouldn't change, so I tested that and man he's right, longer battery life and no change in sound.

I posted pictures of inisde of the cavity, so you can see mono switch, and two pics of new and old modules.

[JimmyJ]

Hey Goran,

It's great that you've found a good tech for when you need some work done.  I see he added the summing resistors so that your 1/4" jack is mono.  (When you said "switch" at the beginning of this thread I thought you meant adding a switch as in - drilling a hole and mounting a new toggle switch near the knobs...  Maybe you just meant to "switch" the 1/4" jack to mono output.  English is a messed up language!)

Updating the DS-5's capacitors makes some sense I suppose, just because of their age. I don't think that would have a noticeable effect on noise levels or audio output, but it is a component which has a lifespan and putting in new ones should extend the life of your power supply.   

And swapping the IC chips or opamps ("preamp modules") is an interesting idea.  I think there are a few "plug and play" options for our board's opamps but I've never experimented with swapping them.  I've stuck with the 5534s as I figured Alembic made that choice on purpose.  I'm presuming they chose that chip because of #1 sound quality in the circuit, #2 reliability, and perhaps #3 ubiquitous availability.  We know that the cost of components is not an issue so...  Anyway, as long as the tone and output level of your bass sound right to you then having an extended battery life is a nice result.

Good stuff!
Jimmy J

[goran]

Hey Jimmy, yea sorry for my english, but yes I meant swapping from stereo to mono...
I'll play now with these modules and then swap them again just to see/hear if there is any difference. Those modules are from 80's so thinking that maybe technology went here in a good way to swap them... we'll see... hope Mica can chip in about this!

Thanks!

Goran

[keith_h]

The 5534 has a  lower noise rating than the TL071. The 5534 also has a wider bandwidth. Whether these differences are noticeable anyplace other than on the bench I can't say.  The TL071 has lower power requirements.

I want to start with that I  have never seen a schematic of the Series electronics so this is just a general observation. I haven't done any op amp circuit design in 40 years but I did work with dual op amp The 5534 requires an external buffer if used as the first stage from something like a guitar so will have have a Jfet in front of it. The TL071 has the Jfet built in. I don't know the effect if any on the circuit just swapping one for the other. I would just go with how it sounds to you.

Way back when I was designing the preamp that is in my Jazz Bass. I settled on the NE5532 but also played around with easy to obtain  LM1458's. While it could just be me I noticed a difference between different LM1458's I plugged into the circuit which is one reason I settled on the NE5532, dual version of 5534, as it was more consistent. 

[goran]

Thanks Keith, I'l do more swapping in future, but for now I can't hear the difference and I like having extra juice on batteries. Wondering how it will sound 1 month from now playing on this modules and then swapping them back...