Blending 2 pickups. Is there a way around the volume roll off with both pickups blended?

[vinorange]

Recently I’ve been thinking how disappointed I am with fender volume, volume, tone controls and the way that the volume dies so much when both pickups are on full. I realise this is due to the additional resistance of the other pickup’s circuit acting to resist and therefore reduce the output but I wondered is there a way around it.

I had wondered about passive blend control but apparently the same thing happens at the centre detention of the blend control I.e. volume roll off.

I had wondered therefore whether to use an active blend control. I think EMG do one but I can’t find out whether that can be used with passive volume and tone pots.

I also don’t really want to go full active preamp as I’ve suddenly realised that amps are better at eq than most preamps.

So my question is what am I to do to have equal volume whether on bridge, mixed or neck pickup? The bass in question is an 80s MIJ Fender Jazz but it happens with all my Fenders.

Just asking!

Edited October 25, 2018 by vinorange

[BassBunny]

Think you have answered your own question. An active balance control is the answer. Quite a few pre-amp manufacturers make them and that is the only way to avoid the problem you have.

I know Mike Walsh, Zoot Bass, and Maruszczyk have used the Noll one to great effect. It's called a MixPot. http://noll-electronic.de/bass-electronics/mixpot/

Wouldn't mind betting John East could sort one out for you.

[vinorange]

5 minutes ago, BassBunny said:

Think you have answered your own question. An active balance control is the answer. Quite a few pre-amp manufacturers make them and that is the only way to avoid the problem you have.

I know Mike Walsh, Zoot Bass, and Maruszczyk have used the Noll one to great effect. It's called a MixPot. http://noll-electronic.de/bass-electronics/mixpot/

Wouldn't mind betting John East could sort one out for you.

Thank you. I’ll have a look around. I thought active blend was the only way but have never tried one in an all passive set up.

[Bridgehouse]

John East’s Uni Pre definitely does this. 

[Bridgehouse]

In fact, John’s uni pre has separate gain trim pots on the volume board to adjust the balance between them which is flippin’ useful!

[itu]

Blend solutions from oldest to newest:

I: V + V and 1 - 2 T pots, passive. Microphones and pots have influence on each other. Hi-Z out.

II: Passive blend pot, master volume. The idea is that the two carbons run only to halfway of the 270 degree turn. This way the mic is full on after 135 degrees and the other mic starts to go to -infinity. Hi-Z out.

III: Volume and passive blend pot (or V + V) and an active preamp. Mics and pots have influence on each other. Low-Z out.

IV: Preamp with two active inputs. Mics go to separate active buffered inputs before blend and volume. This way the mics or other electronics do not affect each other. Low-Z out.

[BassBunny]

10 hours ago, Bridgehouse said:

John East’s Uni Pre definitely does this. 

I think all John's pre-amps have buffered inputs and the fact that they are modular I'm wondering if you can use just the Vol/Blend module on its own as the OP doesn't want a completely active setup.

The Noll MixPot is purely an active Blend control and does nothing else.

[vinorange]

10 hours ago, Bridgehouse said:

In fact, John’s uni pre has separate gain trim pots on the volume board to adjust the balance between them which is flippin’ useful!

I was trying to keep all other controls passive but just have an active blend. Isn’t the uni pre a full modular preamp system or does modular mean you can use as ,icy or as little of the modules as you want?

[BassBunny]

1 minute ago, vinorange said:

I was trying to keep all other controls passive but just have an active blend. Isn’t the uni pre a full modular preamp system or does modular mean you can use as ,icy or as little of the modules as you want?

Looks like we were typing at the same time. I would give John a call and have a chat. He is very helpful.

[vinorange]

2 minutes ago, BassBunny said:

I think all John's pre-amps have buffered inputs and the fact that they are modular I'm wondering if you can use just the Vol/Blend module on its own as the OP doesn't want a completely active setup.

The Noll MixPot is purely an active Blend control and does nothing else.

Yep I think I was just after solving the blend issue rather than going full active. I’ve had John East preamps in quite a few basses and they were fantastic but then I’ve gone all old school, valvey and passive.

[ikay]

If you  back off each vol control just a touch (to around 90-95%) this decouples the pickups and eliminates the 'both full on' loading problem. Use this as your basic 'full on' setting instead of 100%. You'll also find that never going above the 90-95% point will give you much finer control for mixing the pickups. Overall output will drop slightly but that's easy to compensate for at the amp input gain end.

Alternatively use an active blend!

[skelf]

You can get just an active blend from John East.

[vinorange]

58 minutes ago, ikay said:

If you  back off each vol control just a touch (to around 90-95%) this decouples the pickups and eliminates the 'both full on' loading problem. Use this as your basic 'full on' setting instead of 100%. You'll also find that never going above the 90-95% point will give you much finer control for mixing the pickups. Overall output will drop slightly but that's easy to compensate for at the amp input gain end.

Alternatively use an active blend!

That takes discipline. I know from experience I’m not good with that.

I wonder why there aren’t pots that have a detent at 90-95% to assist in compensation for a known issue.

Active blend may be the best option for the ill disciplined!

[itu]

On 26/10/2018 at 11:46, vinorange said:

I was just after solving the blend issue rather than going full active. ...but then I’ve gone all old school, valvey and passive.

Remember: One active component in the chain and you are lo-Z = no more passive.

Passive system with two mics just has its drawbacks or sounds, depending on one's attitude. There have been trials to modify the instrument's active output to hi-Z with transformers and whatever but let's say that the results vary.

Of course, there is a possibility to build step attenuators that work as mentioned. I have used rotary ELMA switches and metal film resistors. The maths is pretty easy to handle - you can make 3 or 6 dB steps or what ever else you want. Then it is just soldering.

[vinorange]

53 minutes ago, itu said:

Remember: One active component in the chain and you are lo-Z = no more passive.

Passive system with two mics just has its drawbacks or sounds, depending on one's attitude. There have been trials to modify the instrument's active output to hi-Z with transformers and whatever but let's say that the results vary.

Of course, there is a possibility to build step attenuators that work as mentioned. I have used rotary ELMA switches and metal film resistors. The maths is pretty easy to handle - you can make 3 or 6 dB steps or what ever else you want. Then it is just soldering.

I may well be on the verge of brain fog. I can feel it building up in my frontal lobes.

So if I add an active blend pot then my system is now all active? I guess it must be as it’s now powered but the volume and tone controls would still function in the same way wouldn’t they?

Am I convincing myself that active is best or maybe a bass with one pickup? That would solve any blend issues! 

[itu]

- I am so sorry: I can put everything together in to a very short message, or I start a book. Hope this helps. -

High impedance (hi-Z)

Pure passive system is hi-Z, because a passive pick-up/mic has lots of wire in the coil. It is high impedance by nature. That is also the reason to use high Resistor values in the pots (V and T; typically 200 000 - 500 000 ohms). If you have two pickups, they affect each other if they are connected together with wire and/or pots, which also have an effect on the system.

 

Low impedance (lo-Z)

A lo-Z system has at least one active part (blend, bass, middle...) somewhere in the signal chain, which is powered by a battery or some external power source (see: Alembics, EBS preamps...) and drives the signal line. Low amount of wire in the pickup equals very, very low output, so true lo-Z pickups (like EMG) NEED a preamp. Not because of the impedance but to amplify the minimal signal level.

 

The biggest thing to understand here is that if you change any part of the hi-Z ("passive") signal chain to lo-Z ("active"), the system becomes lo-Z. Once more: Active equals low impedance (lo-Z). That's all. Everything else can be "passive" or rather "hi-Z": You can use big resistor values for pots, because high resistor values are OK for BOTH active AND passive use. Low resistor values are good for active only.

Lo-Z has advantages like cable lines can be longer and the signal does not get disturbed so easily by other signal sources (like radios). But you need the power source (a 9 V battery, anyone?). If you want to have an A/P switch somewhere (in case of died battery), you also need to bypass the active (i.e. battery driven) parts, too.

This noll blend pot has the inputs for pickups and after that you can put a volume pot. I think that everything from 25 k to 500 k is OK. From the electronics point of view it is somewhat cumbersome to have the blend as the first pot after pickups. But the layout in the bass body is naturally V - blend - tone control(s). And as said, V and T can be hi-Z or lo-Z, your choice.

http://noll-electronic.de/files/a91_mixpot_wiring_diagram.pdf

[vinorange]

I guess I understand that now. Maybe I’ll mess about with the 90-95% pot settings to see if I can get a decent blend before going down the active blend route.

[MoonBassAlpha]

If the 90-95% thing really works, why not wire a 47k resistor in series with each pickup and use the volumes or blend to their max (assuming 500k volume pots), or  22k with typical Fender jazz 250k pots.

[ikay]

10 hours ago, MoonBassAlpha said:

If the 90-95% thing really works, why not wire a 47k resistor in series with each pickup and use the volumes or blend to their max (assuming 500k volume pots), or  22k with typical Fender jazz 250k pots.

Yes, that's what they did with the early '60 stack knob Jazz. They used a larger resistor value (220k!) but I'd experiment with much lower values and find the minimum value with the desired effect. The pots are log so backing off 10% equates to around 20-30% of pot value). The resistors would need to be wired as shown in the modded diagram below. I prefer to just set the vol controls manually as it's not really necessary to make any mods to get this effect and you still have the 100% tonal options as well.

Edited October 29, 2018 by ikay

[EliasMooseblaster]

On 25/10/2018 at 23:06, vinorange said:

Recently I’ve been thinking how disappointed I am with fender volume, volume, tone controls and the way that the volume dies so much when both pickups are on full. I realise this is due to the additional resistance of the other pickup’s circuit acting to resist and therefore reduce the output but I wondered is there a way around it.

Not wishing to derail, but how much of it is down to a loss of signal, and how much is the "perceived" volume? One of the things that characterises the "both on full" setting is the sudden chasm where all the mids used to be! Backing off one of the volumes a touch puts some definition back in the tone...or is this just the way the loading problem manifests itself acoustically, and that I really need to get my head round the electronics in a passive bass?

[chris_b]

I would have thought he solution was obvious. If you really don't like the volume drop off, back off one of the volumes until the "drop off" goes away.

But. . . you need to take a step back and understand what the volume controls on the bass are for. They are not there to get you the maximum volume. They are there to balance the pickups in a way that makes the sound you want. After that you use the volume on the amp to make your sound as loud as it needs to be. 

[vinorange]

 

1 hour ago, chris_b said:

I would have thought he solution was obvious. If you really don't like the volume drop off, back off one of the volumes until the "drop off" goes away.

But. . . you need to take a step back and understand what the volume controls on the bass are for. They are not there to get you the maximum volume. They are there to balance the pickups in a way that makes the sound you want. After that you use the volume on the amp to make your sound as loud as it needs to be. 

I do still suffer from “all knobs on full” syndrome though despite my supposed advancing years and wisdom.

[Deedee]

On 29/10/2018 at 11:06, chris_b said:

I would have thought he solution was obvious. If you really don't like the volume drop off, back off one of the volumes until the "drop off" goes away.

But. . . you need to take a step back and understand what the volume controls on the bass are for. They are not there to get you the maximum volume. They are there to balance the pickups in a way that makes the sound you want. After that you use the volume on the amp to make your sound as loud as it needs to be. 

Be gentle with me here because I’m a bit of a technophobe, but I have the same issue on my old Aria SB-R80. Turn both volumes up full and one wipes the other out. I hate the fact that I have to back them off slightly to get a balanced sound 😡.

[Bridgehouse]

On 29/10/2018 at 11:06, chris_b said:

I would have thought he solution was obvious. If you really don't like the volume drop off, back off one of the volumes until the "drop off" goes away.

But. . . you need to take a step back and understand what the volume controls on the bass are for. They are not there to get you the maximum volume. They are there to balance the pickups in a way that makes the sound you want. After that you use the volume on the amp to make your sound as loud as it needs to be. 

Why do single pickup basses have a volume control then?

[chris_b]

9 minutes ago, Deedee said:

but I have the same issue on my old Aria SB-R80. Turn both volumes up full and one wipes the other out. I hate the fact that I have to back them off slightly to get a balanced sound

That is not really logical!

Transfer your OCD from "volume controls must be full on" to getting "a better tone".