Triode mode Prima Luna

[Haselsh1]

OK, I have now had my Prima Luna pre/power combo for around one year and although it hasn't been used very much at all, I am now used to the sound. Way back when, I moaned quite a bit about using it in triode mode rather than ultralinear as I just didn't think it sounded very good but last night changed that for the two of us. We warmed up the system and started listening to an album on CD by Greyboy but this time at a fairly low level of volume. I then switched it to triode mode and it sounded bloody glorious. I can only deduce from that, that it doesn't like playing in triode mode unless the going is good. My next attempt will be playing vinyl in triode mode. We think that maybe we should try out a bit of Quantic, maybe the 5th Exotic on vinyl. Looking forward to it.

[Haselsh1]

Well, been listening to vinyl in triode mode for two days now and Jesus, what a difference.

Albums were: Porcupine Tree 'Signify', Spanky Wilson and the Quantic Soul Orchestra 'I'm Thankful' and Sting '57th and 9th'.

The first thing that smacked me in the face was the huge difference in bass quality. I have obviously been completely oblivious to what the Denon DL103 can produce on electric bass guitar but not any longer. The quality is sodding astonishing.
There is also so much more depth and extension to the bass. The midband is now so natural and relaxed and way more realistic. The treble is still there but under much greater control. This is how I remember EL34's sounding from decades ago.
The whole sound is now very valve having lost every bit of its frantic, rather sterile sound. When I bought this power amp and got it home I did think that I had never heard a valve amp sound like this before. Now I know why.

The sound has now gone from a rather frantic digital presentation to what I can only describe as real tonally laid back quality. This is what I was expecting all along. So glad I didn't return it though cannot think why. Yes, this sound would not suit all but it definitely suits me.

[southall-1998]

Nice one!

S.

[JohnJo]

Have you noticed any loss of power Shaun?

[Haselsh1]

Have you noticed any loss of power Shaun?

Oh yes John, a considerable reduction in power which is probably why I am now finding things OK because I am listening at a lower overall volume.

[Lawrence001]

I tried triode mode with my Yarland and initially thought the bass was much tighter but after a while realised there just wasn't much of it. I did play at the same (moderate) volume though.

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[Haselsh1]

I tried triode mode with my Yarland and initially thought the bass was much tighter but after a while realised there just wasn't much of it. I did play at the same (moderate) volume though.

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Yeah Lawrence I wonder why things are so different. Mine has gone up a whole level in quality not just in the bass but mostly in the bass. The presence and definition is massive now compared to ultralinear mode which is brash and quite unpleasant. There is also much more heft to the low frequencies which is just not there in ultralinear. Altogether a way better sounding amp now. I have of course had to turn up the volume a little though.

[JohnJo]

Output impedance is probably lower in triode mode which should improve the bass definition.

[Haselsh1]

Output impedance is probably lower in triode mode which should improve the bass definition.

OK John. I have to take others words for such things as my knowledge of electricity and its mysticism is beyond me.

[JohnJo]

Have a read at the technical bits in the grey boxes including the graphs. Frequency response will be different for UL vs Triode, which tap you're using (8 or 4 ohm) and the load your speakers present to the amp.

http://www.absolutesounds.com/pdf/main/press/PrLDiaLo%20PrPowerar.pdf

[Haselsh1]

OK, I was told back around 1996 when I bought my first valve amplifier that if one was using eight Ohm or higher loudspeakers then one should be using the four Ohm output tap. I have always done this as good measure without completely understanding why but yes, it makes sense that it would reshape the frequency response. I have quite clearly heard a difference in sound between triode and ultralinear but I do not think this is just down to frequency reshaping. What I hear is not just down to effects in frequencies as if that were the case then the same result could be had by using a graphic equaliser. What I have here is a clear improvement in bass clarity and presence. There is so much more detail in the way the bass guitar is being played. Yes, there are also differences that are clearly frequency based as the top is more rolled off and there is less edge to vocals. I just find all of this extra detail and texture mesmerising.

[Haselsh1]

OK, read the article, well the grey bits and understood some of it. There appears to be quite some difference with all of its various operating modes. I can't agree about the triode sound being more 'tubey' as I have only found that sound being more traditionally EL34 in sonics as I remember them from decades ago. For my amplifier though in my system triode mode is just so much more sublime than ultralinear. I remember hearing an Audion Sterling ETSE back around 2003 and its midrange was to die for. Yes OK, it was single ended but Jesus that midband was fantastic. I now have a bit of that sound. By the way, I use the four Ohm tap as my speakers dip down to around 3.9 Ohms in the bass.

[Haselsh1]

Oh bugger it ! Just played Gary Numan's Savage album in triode mode and it has done it no favours at all. This really doesn't work very well. I'm guessing that synthesised bass just doesn't have the complexity of a stringed instrument and therefore the subtleties of triode mode just do not come across.

[JohnJo]

I think that's the reason Primaluna give you the option to switch between the two, pick which sounds best for the music.

[User211]

FWIW I had a pair of Ayon Orthos XS monos for a few months which were triode/pentode switchable. 250W and 400W respectively using KT150s.

Driving a revised and much better built Apogee Duetta design, there was remarkably far less difference in the two modes than I expected. Pentode mode on the 4 Ohm taps is where is remained, because it just sounded fractionally better IMHO. 250W in triode mode is easily enough to drive the speakers to a good volume level, so there's no reason triode mode should have been much of a disadvantage power delivery wise.

That said I could get them to shut themselves down in triode mode, and so could a Diva owner who tried them later:D He ended up with the new ARC 250 monos.

[Haselsh1]

John, yeah I guess that is the reason they provide the option. I would say that most of my choice of music would be better with ultralinear. Justin, I am indeed using the four Ohm outputs but I have tried the eight Ohm ones and not really heard a difference.

[User211]

John, yeah I guess that is the reason they provide the option. I would say that most of my choice of music would be better with ultralinear. Justin, I am indeed using the four Ohm outputs but I have tried the eight Ohm ones and not really heard a difference.

I believe what you have said BTW Shaun. I was just saying with that particular amp not much difference. The point is it isn't a hard and fast rule that triode mode is always better, as you have worked out for real:) Same goes for taps. Sometimes the tap that is supposed to work best doesn't - when you hear a difference that is.

[Haselsh1]

OK guys there just seem to be so many bloody variables ! I have also tried KT88's and though they sounded much better, my amplifier didn't seem to like them. There was a strange cracking sound every time I switched off. Putting the EL34's back in, no problems at all.

[Lawrence001]

Reading this has induced me to try triode mode again with my new speakers (BKS 128 ribbon hybrids). I've got them sounding pretty good by restoring the tonal balance of ultralinear by pushing them nearer the wall (rear ported) and toeing them out a bit.
Btw, I always switch my amp off to switch the mode, do you know if I actually need to do this?

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[Haselsh1]

Reading this has induced me to try triode mode again with my new speakers (BKS 128 ribbon hybrids). I've got them sounding pretty good by restoring the tonal balance of ultralinear by pushing them nearer the wall (rear ported) and toeing them out a bit.
Btw, I always switch my amp off to switch the mode, do you know if I actually need to do this?

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Sorry Lawrence, I don't know but I know that I don't have to. It does make a gentle tick through the speakers but nothing to worry me. Now my speakers are also rear ported so maybe I could do a bit of experimentation with the rear wall also.
They are currently about three feet from the wall and sound OK but my room is around 20 feet long and maybe 13 feet wide. I find with my speakers that toeing them in slightly helps the imaging by giving more focus to the centre and I also found that they sounded best with my current speaker cables having tried a few different types.

[Haselsh1]

Oh yes and about 95% of my triode listening has been with vinyl and not CD.

[maxrob200]

I have found that in my PL when using KT88's (less hifi ish), I preferred Triode mode. changing to EL 34's I preferred ultra-linear mode. Both on 4 ohm taps

[Intenso]

I have a KT88 based Yaqin 100B which has both Triode and UL modes.

I run my speakers on the 40hm taps and have found the same results as you.

I prefer Triode mode as the bass blooms in a very appealing way and the overall sound is sweeter and more musical.

What I have found though is that UL mode is far more dynamic and pushes the soundstage forward whereas in Triode mode the soundstage shrinks behind the speaker line.

What KT88s did you use as this may have a bearing on the crackling you heard?

[Sherwood]

Surely this was predictable as with most switchable designs. I have an Art Audio Quintet which is also switchable between modes. Triode mode is markedly sweeter than pentode and better on most counts, but begins to fall down when pushed too hard or when used with demanding speakers. I used mine with Rogers LS3/5a speakers in triode mode for many years and despite the low efficiency of those speakers never had any problem with volume levels.

Geoff

[Haselsh1]

I have a KT88 based Yaqin 100B which has both Triode and UL modes.

I run my speakers on the 40hm taps and have found the same results as you.

I prefer Triode mode as the bass blooms in a very appealing way and the overall sound is sweeter and more musical.

What I have found though is that UL mode is far more dynamic and pushes the soundstage forward whereas in Triode mode the soundstage shrinks behind the speaker line.

What KT88s did you use as this may have a bearing on the crackling you heard?

Yes, I certainly have to agree with this after lots of listening. I have also started using the eight Ohm output with the B&W's and it has hugely improved the sound. Very definitely the soundstage has way more depth in triode mode and yes, the bass has a nice 'full' quality. The sparkle and air though is much better in ultralinear.

Really cannot remember the KT88's I borrowed but I don't think the power amp was fully compatible with them. Yes, the bias switch was set OK but every time it was switched off it cracked through the speakers.