Valve vs solid state power relative to impedance

[FennerMachine]

I've been reading more about valve and solid state amps.
Just read an article that talks about power output relative to speaker impedance.
It says solid state amps are inversely proportional, valve amps directly proportional to speaker impedance.
So solid state amps supply more power to the lower impedance range but valve amps to the higher impedance range of the speaker.
If this is correct, could this explain why certain combinations of amps and speakers sound better with valves?
The speakers simply work better with valves?
Obviously the opposite would be true that some or many speakers are designed to sound good with solid state amps so sound awful with valves.

 

[Rethep]

Thinking while writing:

The valve-amp will not give you more power! It is not good at delivering current in general because of it' s own high output impedance.

That' s why most valve-amps have a 8 and a 4 ohm connection on the output transformer. If your '8 ohm' speaker drops to under 4 ohms, mostly in the lower freq (around the port freq of a bass reflex speaker), then you better use the 4 ohm tap to have a better 'interface' between speaker and amp. You will have more 'spare' current and tighter low end.

The 'real' power (in Watts) is less important! Only when you are dealing with a single ended valve-amp with very low power. Most people who listen to valve-amps prefer ambiance a little over dynamics (loudness), and listen lower volume in general i.m.o..

Furthermore the sensitivety of the speaker is important, but not crucial on it' s own. An 8 ohm speaker (on the whole freq. range) with a low sensitivety can be compared to a 4 ohm speaker with a high sensitivety.

If you want to compare, you best judge by auditioning!

 

[FennerMachine]

Thanks for the reply.
Your right, valve amps won't give more power.
After reading some measurements of valve amps it seems that they supply the same power across a range of impedance levels whereas solid state amps increase output to lower impedance.
I've tried my speakers with valves amps almost 2 years ago and I'm still considering them.
I'm looking for an objective logical reason for why that amp made my speakers sound so good!

 

[Vladimir]

Valve amps were made for 16 ohms speakers with 100dB+ efficiency in the time when 8 ohms and 90dB was considered inneficient. But then small infinite baffle enclosures and monster SS receivers became the trend.

 

[FennerMachine]

So Vladimir, are you a solid state only man?

 

[Vladimir]

So Vladimir, are you a solid state only man?

Only by budget constraints.

 

[FennerMachine]

Considering Icon Audio ST40 at about £1800.00
Small room.
Good enough quality?

 

[Vladimir]

Not ideal for those 88dB Quads. You'll have to trade them in for more efficient speakers to go truly oldskool.

 

[lindsayt]

Fennermachine, for £1800 you'd get more improvement to the sound of your system by going for a full sized Altec, EV, JBL, Klipsch, Vitavox type high efficiency speaker. And then putting any money left over from your budget towards a decent matching SET when you could afford that.

If you don't want to go down the full sized speaker route, stick with what you've got and enjoy it for what it is, as you already have an enjoyable enough system.

 

[FennerMachine]

Thanks for suggestions lindsayt, but I'm done demoing speakers.
I want to get the best out of the Quads I already own.
The only alternative that I would currently consider after much demoing is the Marantz PM8500 or PM-14S1.
Not sure if PM8500 would be a good enough improvement if one at all from what I have.
Time to arrange home demo's.

 

[lindsayt]

By all means try a push pull valve, or one of the higher powered SET's with your Quads.

It'll be interesting to see how you get on, inparticular whether you think it's worth the extra money or not.

In my main system, where the speakers are about as SET friendly as you're likely to get, if someone were to play an unfamiliar piece of music and to use either my SET amp or my best solid state amp in a blind single amp demo, I'd struggle to tell which amp was being used.

If a very familiar piece of music were used, I might be able to tell which amp was playing. In a direct A/B demo I'd have a reasonable chance of telling which was being used.

In my main system, my best solid state amp cost me 1.5% of the total system budget. My SET amp cost me about 15% of total system budget.

 

[drummerman]

Considering Icon Audio ST40 at about £1800.00 Small room. Good enough quality?

I was trying to see if I could find some plots on your Quads but failed.

The Icon should be good though for fairly high, even uncomfortable volumes, even for your 88db/w (manufacturers spec), probably closer to 86db/w speakers. Bearing also in mind that 'clipping' will be less abrupt and softer than with SS and will likely result in softening of sound rather than harsh distortion by the time the (good quality) output transformers of the Icon saturate.

Others already explained the intricacies about volts vs current. Assuming the Quads are not highly reactive and punishing load, you should not encounter issues such as large frequency response variations.

At best you will revel in the things a good valve amplifer* can do, as you know as a previous owner of such a product. - Fleet of foot sound which often eludes SS behemots with super regulated supplies. Micro dynamics which jump out at you even at lower volumes and a bass which may not have the solidity of mega watt transistor amplifier but which is bouncy and integrates superbly with lower mids, in short effortless listening.

*Obviously, not all valve amplifiers are created equally. I have heard some very 'scratchy' and bright sounding ones.

Don't Icon offer a home trial?

 

[Vladimir]

By all means the Quads are not valve matched speakers. The manufacturer specified 88dB efficiency, which from my personal experience from reading a lot of measurments articles in various publications, in real world always equates -3dB from specified. So they will be 85dB in real world conditions. And they are 4-8ohms at least, if not lower. Like I said, not ideal as the manufacturer has specified recommended amplification of 40W-200W.

The whole point of going valve is to have high sensitivity speakers. Can the Quads be loud enough in a small room with 35W valves (damping factor of 5)? Sure. But IMO they won't sound as good as true high efficiency speakers on the same amp. There is much more to the high efficiency concept than just decibels. I'm sure more experienced members in this area will confirm this.

 

[Rethep]

Yes, there is more to it then just efficiency! What's also important is: 'how deep does your speaker go in the lower frequencies ? My former Epos went -3 dB at 60 Hz and 85 dB eff.. My current speaker (Peitho 303) goes to 35 Hz (almost one octave lower), -3 dB and 90 dB eff.. The result is that i have a less rythmic, but much deeper, low end now. The Epos load was much easier than the Peitho' s and sounded a little more dynamic..

Instead of the 'Icon' you could also consider a 'Prima Luna' or the Cayin A55T.

 

[Infiniteloop]

By all means the Quads are not valve matched speakers. The manufacturer specified 88dB efficiency, which from my personal experience from reading a lot of measurments articles in various publications, in real world always equates -3dB from specified. So they will be 85dB in real world conditions. And they are 4-8ohms at least, if not lower. Like I said, not ideal as the manufacturer has specified recommended amplification of 40W-200W.

The whole point of going valve is to have high sensitivity speakers. Can the Quads be loud enough in a small room with 35W valves (damping factor of 5)? Sure. But IMO they won't sound as good as true high efficiency speakers on the same amp. There is much more to the high efficiency concept than just decibels. I'm sure more experienced members in this area will confirm this.

The thing about Valves is that the sound quality you arrive at is not a strict science. ProAc speakers for example, are not particularly efficient, but they are an easy load for a Valve Amp to drive, and therefore sound great with them.

I myself drive a pair of Sonus Fabers (4 Ohm/ 88 db) with w 24 watt SET Amp because I like the sound. The set-up is plenty loud enough too, - even for parties!

 

[FennerMachine]

Before I arrange home demo's, what about Cambridge Audio Azur 851a?
On paper and from reviews it looks very well specified and is cheaper than the 2 other main contenders.

 

[FennerMachine]

I've had a look at a few power output charts on Stereophile.
General results for a simulated speaker load are that valve amps can vary by about +/-2db whereas solid state about +/-0.25db.
A 4db swing will almost certainly change the presentation of the music, it is quite a big distortion.
Solid state might vary by 0.5db which is still a distortion but much better.

 

[Rethep]

To give you any idea of some real figures:

Output impedance of, e.g. the Line Magnetic LM-5181A (single ended, 845 tube-amp), dependent on output-transformer tap (recent Stereophile-test):

3.8 ohms (16 ohm tap), 2 ohms (8 ohm tap), and 1.1 ohms (4 ohm tap). Which means a damping factor of 4!

I don't know if it's better (lower) with a push-pull tube-amp.

 

[Rethep]

Yes, but power is not an issue for valve amps because they are not known for that, but for their heavenly inside into the music! In the long run 'power' just gets a little boring while the 'dreamy' valve sound never bores!

 

[Andrewjvt]

Private investigations on a valve amp and it sounded so good.

I can understand the love the these amps despite the lower power as they make up for it with the sound

 

[Andrewjvt]

You mean the song by 'Dire Straits' ? It sounds teriffic! And then, that is by far not the best sound quality available, but even the older number 'Wild west end' from their 1st album sounds beautiful with valves! You got the message! ;-)

Yeah mon

 

[Rethep]

You mean the song by 'Dire Straits' ? It sounds teriffic! And then, that is by far not the best sound quality available, but even the older number 'Wild west end' from their 1st album sounds beautiful with valves! 'You got the message!' ;-)

 

[FennerMachine]

Thanks for looking drummerman.
I found an impedance chart for Quad 22L which will be different but likely similar to my 21L2's.
There are a couple of dips to around 4.5 ohms.
One in the bass region, one in mid.
Could this drop in these regions, assuming my speakers are similar, be causing problems for my Denon?
It is rated at 8 and 6 ohm with but not for 4 ohms.
Could this explain some of the mid range distortion and lack of bass control?
If this is a possibility then I think a good solid state amp would be better than a valve amp.
The Icon Audio amps do have a 4 ohm tap though and the benefits you state do appeal to me.