Stacking Tundras

[Pediatrik]

I’m considering changing my amps (2x Akurate 4200), driving a pair of Keltiks. Unfortunately the shelf that contains my equipment (not a dedicated Hi-fi rack due to SWMBO compromise), does not allow four Tundra Stereo or six Tundra Mono unless I stack them two and two.

I remember that you Frederik once explained the downside of stacking Sagatun Mono:s. Does this also apply to the Tundra amps?

[lejonklou]

Cool Pediatrik!

Yes, Sagatun Mono should not be stacked. The top one sounds great but the bottom one doesn't like the weight on its lid and will sound worse. Funny as it may sound, you can hear how it sounds a little compressed, or under pressure, when you compare the two.

Tundra and Tundra Mono are much less affected by this, perhaps partly due to the hierarchy but also maybe due to the larger signals (especially currents) they handle. With the first versions, there was a difference in how warm each case becomes, which influences the idling current which in turn influences the sound. At that time I advised not to stack them.

But with Tundra Mono 2, the idling current can be fine tuned by the user and the same goes for Tundra in its latest version, 2.5. As this offsets most of the difference between the top and the bottom amp, I think stacking them is acceptable.

I would advise putting something below the feet of the amp on top, as they will otherwise leave permanent marks in the paint of the amp below. Four small and thin sheets of plastic is enough.

[Pediatrik]

Great news Fredrik! Then there is no need for hesitation on my part anymore. Now the only question is which combo to choose? Anyone out there that has experienced Keltiks with Tundra Stereo/Mono:s?

[mrco99]

Hi Pedriatrik!

Last time I drove my personal pair of Keltiks was with Klimax Tuneboxes and 2x4200 as well.
Never tried Tundra amps - I think it was still version 1.X at that time but I'd be very curious too to hear them with 4x Tundra stereo 2.5...!

[Pediatrik]

I actually have no doubt they will sound great with Tundra Stereo:s Marco. The real question is if they will sound even better with three pairs of Tundra Mono:s? A fourth pair is unfortunately out of the question spacewise, considering the shelf that holds my equipment...

[Tendaberry]

I actually have no doubt they will sound great with Tundra Stereo:s Marco. The real question is if they will sound even better with three pairs of Tundra Mono:s? A fourth pair is unfortunately out of the question spacewise, considering the shelf that holds my equipment...

I don't think anybody here is going to say, that the Monos won't sound better ;-)

[sunbeamgls]

There's a guy in Vancouver who runs Tundras on the treble and mid for his Keltiks, and I think Bryston on the bass. He used to post quite frequently on the Linn forum but I haven't seen posts from him for quite some time and his user name escapes me just now!

[tokenbrit]

^ finster

[ThomasOK]

I have not tried this with Keltiks but I would say that the three pair of Monos should certainly be more musical than the 4 stereos - quality vs. quantity. While there is certainly benefit in having separate amps for each bass driver in Keltiks (I did the same thing with Isobariks and LK280/SPARKS) it won't outweigh the superior musical performance of the Tundra Monos. A few years ago I had active ATC100s with the built in amps and crossovers, the first speaker I heard that really outperformed my active Isobariks. I thought I had the speaker for the rest of my life. But curiosity got the better of me after hearing how musical Tundra Monos were with several different speakers. So I managed to find a pair of passive crossovers for the ATCs and hooked them up to the TMs. I was unprepared for just how much better the passive ATCs were with the TMs. I didn't put the active crossover/amp packs back in until I was selling the ATCs.

In my experience passive with the best amp will always be more musical than active with the second best amps. That is despite the theoretical advantages an active speaker has. With Keltiks you obviously you don't have the option to go passive but the idea of fewer but better amps would seem to me to apply even more.

[sunbeamgls]

^ finster

Thanks tb!

[lejonklou]

I have not tried this with Keltiks but I would say that the three pair of Monos should certainly be more musical than the 4 stereos - quality vs. quantity. While there is certainly benefit in having separate amps for each bass driver in Keltiks (I did the same thing with Isobariks and LK280/SPARKS) it won't outweigh the superior musical performance of the Tundra Monos. A few years ago I had active ATC100s with the built in amps and crossovers, the first speaker I heard that really outperformed my active Isobariks. I thought I had the speaker for the rest of my life. But curiosity got the better of me after hearing how musical Tundra Monos were with several different speakers. So I managed to find a pair of passive crossovers for the ATCs and hooked them up to the TMs. I was unprepared for just how much better the passive ATCs were with the TMs. I didn't put the active crossover/amp packs back in until I was selling the ATCs.

In my experience passive with the best amp will always be more musical than active with the second best amps. That is despite the theoretical advantages an active speaker has. With Keltiks you obviously you don't have the option to go passive but the idea of fewer but better amps would seem to me to apply even more.

Matches my experiences exactly.

[Pediatrik]

Seems like six Mono:s is the way to go then!

Just out of curiosity Fredrik, would placing Tundras vertically affect their performance? Just realised that the shelf would fit more Tundras if they were placed vertically...

[lejonklou]

Seems like six Mono:s is the way to go then!

Just out of curiosity Fredrik, would placing Tundras vertically affect their performance? Just realised that the shelf would fit more Tundras if they were placed vertically...

It will absolutely. What I don't know is how good it could become, because I haven't tried it.

The feet have quite a big influence on how the amplifiers sound. Not just my amps, but all amps, even when they're machined from a solid annealed billet. Everyone who's experimented with this knows it. Put something soft below and the music will get softened. Put it on pointy metal cones and it will sound sharper. The Tune Method is the only way to get it right - ignoring the sonic differences and judging how easy it becomes to understand the musical message.

The feet of Tundra Mono are positioned in a square with 260 mm apart in both directions. They're made of soft plastic rubber and have one large and one small metal washer above them - the large one supports the entire upper surface of the rubber foot and the upper makes the contact area with the case a little smaller. Together they are the most musical foot I've been able to achieve for this particular case and up to a certain weight, above which they don't sound as good anymore. I have one drawer and one box full of experiments made of different types and sizes of wood, metal, felt, rubber, plastic, stone, ceramics and cardboard. And combinations of them. Every model sounds so different that it's almost silly. But none has been better than that simple grey foot with two washers.

A vertical position would first of all require proper ventilation through the inside, so that the power supplies stay cool. That excludes standing them on the side, it would have to be on the front or on the back for the air to flow through the ventilation holes. On the front is easier, as on the back you have connectors, and the amp would then have to hang suspended above the shelf below for the ventilation to work.

Then remains the question of what to put between the front and the shelf below. With nothing in between I suspect it wouldn't sound great. Something with the right softness and the right amount of contact area. I think it could take a while to find something optimal. And I don't know how far you would reach, musically. My guess is that the original position is likely to win in the end.

[Pediatrik]

Thank you for your comprehensive answer Fredrik! I knew it was a crazy long shot, but hey if you don’t ask... I think I will settle for three pairs of Tundra Mono, stacked in pairs, horisontally.

[finster]

Hi, just caught up with this thread I haven’t been online for a while. As mentioned I do indeed run two Tundra stereo amps on my Keltiks for high and mid duty (never tried on bass - run 4 channel Bryson instead). I have found the bass drivers on the keltiks respond well to power and on paper brystons have more “juice” (essentially a 4 mono block setup).

I can comment very favourably on the quality and naturalness of the musical reproduction on tundras over and above the Linn amps I used to run. I used to have Klimax XOs and then moved to exakt with katalyst, the latter being even more transparent to my ears. You will not be disappointed. The only caveat is I have non Linn drivers in my keltiks for mid and high. Running Seas and hiquphon respectively again taking the keltiks to a higher level of performance IMO.

Let me know if you need any further info with respect to Tundra/Keltik matching.

Cheers
Andy

[Pediatrik]

Thanks for the info Andy! I’m currently looking at running them either with three pairs of Tundra Mono:s or two pairs of Tundra Mono:s and two Tundra Stereo. Just out of curiosity do you run yours with one or two Klimax Exaktboxes?

[finster]

I just use the one Exaktbox with 6 channels, that's all you need as Keltik is a 3 way speaker.

In the process of integrating a subwoofer to the system, but using mini-dsp for this. This is quite "involved" :)

Sorry cant help you on using your Tundra's on the bass drivers, I assume the one option you mention is to run 4 x Monos on the bass, that should be more than adequate and expect sound rather nice. I has considered another 2 tundra stereos for the bass as well which may also have been an improvement in my setup.