Tundra Stereo idea

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Defender
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Tundra Stereo idea

Post by Defender » 2019-09-09 21:08

Hey Fredrik,

I wanted to ask you since a long time if you thought about offering the Tundra Stereo in a bridgeable configuration. Not sure if your base design allows it or if it would be a compromise on musicality somehow.

I think of it as a possible upgrade path. People could start to buy a Tundra Stereo. Later if money allows and they want to have the Tundra Mono they wouldnt have to sell the Stereo but buy another Stereo and bridge every Tundra Stereo for a left and a right channel (actually making two monos out of the two stereos).

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Re: Tundra Stereo idea

Post by lejonklou » 2019-09-09 21:49

Hi Defender!

Thank you! I love suggestions like this, they always make me think along a different path than the ones I am currently occupied with.

Tundra is bridgeable and I have used that on a few occasions to get a lot of power. The drawback is that it doesn't sound as good, which is the case with all amps that are bridged (you basically double the errors). So the pair of Tundra stereo's that you bridge will perhaps not be perceived as an upgrade:

+ The output power per channel will be four times greater (quantity upgrade)
+ Each channel will have its own pair of power supplies (quality upgrade)
- Each channel will have more noise and distortion (quality downgrade)

When I have tried this, I have preferred using a single Tundra stereo. It has a musical agility that I think is partly lost in the bridged configuration.

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Re: Tundra Stereo idea

Post by Defender » 2019-09-10 11:01

How could I think you didn’t tried out that already - so my next questions might be stupid ;(

is there a way these errors would cancel out?
like providing the loudspeaker output as balanced output ... minus and plus as live outputs?

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Re: Tundra Stereo idea

Post by lejonklou » 2019-09-10 15:02

Defender wrote:
2019-09-10 11:01
How could I think you didn’t tried out that already - so my next questions might be stupid ;(

is there a way these errors would cancel out?
like providing the loudspeaker output as balanced output ... minus and plus as live outputs?
Well I have tried bridging, but there are countless other things I haven't, so please keep the ideas coming!

Sometimes it's the "stupid" ideas that are the best, at least if one thinks them through and use them as inspiration, instead of dismissing them because in their original form they don't work.

Some errors cancel out when you add two signals of opposite phase, but most don't. I can't think of how to use the ground as well as the two out of phase signals from the output of the bridged amps. The idea with bridging is to double the signal, right? Then you need to use the difference between the two channels to drive the voice coil. Are there any passive loudspeaker designs that use a balanced signal in?

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Re: Tundra Stereo idea

Post by Defender » 2019-09-10 15:55

here is where „half knowledge“ on my side becomes dangerous as I am missing detailed experience with building audio equipment

but I try to explain where the thoughts come from
you might know Nelson Pass from Passlabs (also founder of Threshold) - if not you should maybe try to talk to him at one of the bigger US audio shows - he is a funny guy and also really open with his First Watt designs. He actually gives some of his designs to the DIY community after he sold 1000 pieces of it (First Watt F1 etc.).

So he stated in the user manual of the XA30.5 which is the commercial line of his company:
something like this regarding the connection of the loudspeaker cable: „Please note that, being a balanced output, both of these outputs are electrically live - neither is grounded and should not be treated as ground.“
Those amps work with normal loudspeakers so maybe its a misunderstanding on my side what he means in saying the loudspeaker output is a balanced output (I do know what balanced vs single ended means when connecting a source to a pre to a power amp)

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Re: Tundra Stereo idea

Post by ThomasOK » 2019-09-10 17:32

I think you are confusing balanced interconnections with balanced drive on the speaker. Balanced interconnections have a plus signal, a minus signal and a separate ground. The idea is that by recombining the plus and minus signals in the load, which is done by flipping one, it cancels out noise that would be picked up by the cable. However, it also has the problem that the balanced circuit which drives it, whether in preamp, amp or source, uses additional components - if done correctly twice as many - and that is where the errors come in. Since components are not perfect, the more components the more small errors which tend to build up. So doubling the components is likely to double the errors. This is why Lejonklou components don't have balanced inputs and outputs.

You could call speakers and cartridges balanced devices in the sense that they have plus and minus connections that aren't actual grounds (although many if not most cartridges ground one channel minus to the chassis ground/arm ground). In the case of speakers you can drive them with a bridged amp in which the plus has power going one way and the minus has the power going the other way, in essence increasing the power quite a bit. But it again is now using twice as many components and therefore substantially increasing the errors getting to the speaker. Whereas, the Mono amps don't have those extra components, indeed they have the same or fewer components as one channel of the stereo amp, but those are now in an individual chassis giving independent grounds and better shielding so no real crosstalk between channels. Plus the dual switch-mode power supplies now only drive one channel giving them better control of the amp, and there is better cooling as it is only one pair of output devices. So instead of a bridged Tundra stereo taking you closer to the TM it is likely to take you farther away, just with more power.

By the way, I have read of a "balanced" speaker. Tannoy makes some speakers with a separate earth connection from the plus and minus, which is to be connected to an actual earth point. It earths the chassis of the speaker driver(s) and is said to reduce RFI in the voice coils by better shielding them. One or two others have used the same idea. Safe to say it is far from becoming an industry standard.

One important thing to remember with bridged amps is that you cannot use them with anything that uses a common ground unless you want to blow the amp up. This includes many subwoofers when hooked up through speaker level inputs and many speaker switching devices.
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Re: Tundra Stereo idea

Post by Linntek » 2019-09-10 19:32

lejonklou wrote:
2019-09-10 15:02

Well I have tried bridging, but there are countless other things I haven't, so please keep the ideas coming!

Sometimes it's the "stupid" ideas that are the best, at least if one thinks them through and use them as inspiration, instead of dismissing them because in their original form they don't work.
You asked for stupid ideas...

Try a tundra in bridged configuration but as a stereo amp
One channel non inverting
One channel inverting

Connect two speakers but reverse plus and minus on the speaker connected to the inverting channel.
The speakers will be in phase.
Now - since the most power (current) hungry part is the low frequencies and bass is in phase, you will reduce the power drawn from the power supply.
While both speakers move out, one speaker will draw power from the positive supply and the other speaker from the negative supply.
NAD did this on some of their amps (2200/2600) in the 80's. I believe it was mostly for more power and they didn't use SMPS.

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Re: Tundra Stereo idea

Post by lejonklou » 2019-09-10 20:03

Linntek wrote:
2019-09-10 19:32
You asked for stupid ideas...

Try a tundra in bridged configuration but as a stereo amp
One channel non inverting
One channel inverting

Connect two speakers but reverse plus and minus on the speaker connected to the inverting channel.
The speakers will be in phase.
Now - since the most power (current) hungry part is the low frequencies and bass is in phase, you will reduce the power drawn from the power supply.
While both speakers move out, one speaker will draw power from the positive supply and the other speaker from the negative supply.
NAD did this on some of their amps (2200/2600) in the 80's. I believe it was mostly for more power and they didn't use SMPS.
Thank you Linntek!

I tried this a couple of years ago. Not only on power amps but also on other (stereo) circuits.

Interestingly it's clearly worse.

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Re: Tundra Stereo idea

Post by Defender » 2019-09-14 18:56

this doesn’t really fit to that topic but I think some time ago there was one message comming up if “Boazo Monos” can outrun Sagatun Mono with Tundra Mono.

The question is if integration of pre- and amp
but splitting channels is better than having everything in individual boxes and additional transfer of signals through interconnects.

I know it seems strange to do that as we all think integration should make things worse but is that really the case?

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Re: Tundra Stereo idea

Post by lejonklou » 2019-09-16 23:27

Defender wrote:
2019-09-14 18:56
this doesn’t really fit to that topic but I think some time ago there was one message comming up if “Boazo Monos” can outrun Sagatun Mono with Tundra Mono.

The question is if integration of pre- and amp
but splitting channels is better than having everything in individual boxes and additional transfer of signals through interconnects.

I know it seems strange to do that as we all think integration should make things worse but is that really the case?
I think the question was (and is) rather whether two Mono Boazu could outrun Sagatun+Tundra. And perhaps that's possible, at least on a theoretical level. They will not have a chance against Sagatun Mono + Tundra Mono, however. That becomes apparent really quickly when you compare all the current models with one another.

There are definite advantages with integration. But there are also disadvantages. These tradeoffs are things I'd really like to discuss in detail with a clever bunch of folks who are into electronics, because they appear not only on system level, but within each design.

For instance when drawing a circuit board. Does the advantages of cramming everything into a small tiny area outweigh the advantages of separating the parts that affect each other in a negative way? These decisions can take months to make, as sometimes it's necessary to manufacture and listen to a couple of variations to understand the real impact of each advantage and disadvantage.

To get back to Boazu, the main problem with making a Mono version of it is that it's very integrated. It's not just two channels of preamp and two channels of power amp, but they're all sharing circuits and power regulation. So while cutting a Sagatun stereo preamp into two Sagatun Mono preamps is reasonably straightforward and a big improvement, removing half of a Boazu will leave the remaining half sounding worse, not better. The entire design would have to be remade in order to make two Boazu Mono that perform better than a regular Boazu in stereo.

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Re: Tundra Stereo idea

Post by Defender » 2019-09-18 19:49

I understand and just to say it I am not asking you with the hope you disclose some information which you should rather keep for yourself. Just putting some thoughts on the table.

One advantage in integration of pre and power stage is you could do a perfect impedance matching of pre and power stage which you might not be able to do if not integrated as your devices also need to work independent with other equipment from other manufacturers.

I think the biggest issue is when using the power supplies for both stages it creates interferences but maybe you can solve it somehow.

Interference between signals of the stages I dont believe is as critical -but maybe I completely underestimate this as that statement is not based on measurements or experience.

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Re: Tundra Stereo idea

Post by lejonklou » 2019-09-18 21:40

Thanks Defender!
Defender wrote:
2019-09-18 19:49
I understand and just to say it I am not asking you with the hope you disclose some information which you should rather keep for yourself. Just putting some thoughts on the table.
I don't have many secrets and love to discuss general ideas. The end result is still a matter of implementation and the actual performance depends on many details.
Defender wrote:
2019-09-18 19:49
One advantage in integration of pre and power stage is you could do a perfect impedance matching of pre and power stage which you might not be able to do if not integrated as your devices also need to work independent with other equipment from other manufacturers.
True!
Defender wrote:
2019-09-18 19:49
I think the biggest issue is when using the power supplies for both stages it creates interferences but maybe you can solve it somehow.
True!
Defender wrote:
2019-09-18 19:49
Interference between signals of the stages I dont believe is as critical -but maybe I completely underestimate this as that statement is not based on measurements or experience.
The power regulation is more critical than one expects. This is a field where practical experience plays a big part. Some parts can be grouped, some actually "want" to be powered together, others want to be separate. It's a puzzle one needs to lay when designing the product.

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