Alan Shaw on pairing Harbeths with Tube amplifiers

Analogous

Well-Known Member
Joined
Nov 17, 2017
Messages
3,072
Points
113
Location
Bangalore
I came across this on the HUG forum…he was responding to discussions on tube amp matching with Harbeth speakers.
I am a bit mystified as the Tube push pull amp I use (20 WPC) sounds wonderful with the P3ES. (As does the SS, in a different way)

“ You can drive your Harbeths with any brand, technology, feature set, price, cosmetics and power output that you like and according to your taste and budget. The more you spend, the longer there will be a hifi dealer on your high street.

Tube amplifiers as a class provide a very loose coupling to the speakers that they drive, rather like having a manual car stuck in third gear regardless of whether it is being driven in town, down a steep gradient or up a mountain. This is principally because the output transformer between the tubes and the speakers invokes a two-stage power conversion in the amplifier output transformer as it plays music and delivers energy to the speakers: current to magnetism in the primary from the tubes and then magnetism back to current in the secondary which drives the speakers. Solid state amps do not have this two-step conversion and perform power to the speakers at all frequencies like a silky smooth 10-gear automatic gearbox constantly and invisibly adapting to the impedance of the speaker load i.e. the musical gradient.

This two-step tube drive matter is not at all ideal and introduces numerous insoluble technical limitations, all of which manifest themselves in an unpredictable "suck it and see" relationship between the music, the amplifier and the speakers which I as the speaker designer cannot be expected to know about or even compensate for. You are on your own, in the audio wilderness. I hope that you have time to play and a suitable budget because tinkering over (tube) amps will get in the way of the music - which may be what motivates you anyway.

It seems a pity for the consumer to invest serious money in decent speakers designed patiently and over many long hours for maximum fidelity and then to introduce such massive uncertainty at the point of listening at home about which the manufacturer is powerless to advise.

Of course, our transaction with the consumer is ended - he's paid - and how he subsequently choses to use or misuse the product is of no concern to us excepting that we rely on word of mouth for sales, and demonstrating a system which is below, possibly far below the standard that we have built in does us no favours at all.

If the music is your thing and the equipment (incl. the speakers) just an inconvenient necessity, then you would do very well to take note of the gear that we associate ourselves with at UK hifi shows to demonstrate our speakers and consider that to be an apolitical, pragmatic, cost-conscious solution - and clone it into your own homes. Actually, we are obliged to 'put on a decent show' to minimise know-it-all visitors who about turn when they see what they consider to be ludicrously offensive sub-fi equipment in a demo room; if we could keep those nuisances away we'd be happy to assemble an entire electronic package for the price of a decent suit and a pair of Barkers shoes just to prove a point. There would be zero pride of ownership, it could go bang! at a moment's notice, but it would make music.

Come to think of it: damn them. Let's do just that at the next Bristol show! o_O:)
Alan Shaw
Designer, owner
Harbeth Audio UK
 
Not all like tube sound. I own one basic Fatman hybrid and have owned some other tube amps in the past, but have heard some very very high end tube amps is my friend's showroom.
I personally am not a big fan of the tube sound and prefer SS.

It is sometime funny to read some high end manufacturers stating they have engineered their SS amps to sound like tube amps.
 
funny to read some high end manufacturers stating they have engineered their SS amps to sound like tube amps.
I guess they know there is a market for this?:)
I like both tube and SS sound. For complex, fast paced, music I prefer SS and for mellow, contemplative and laid back music tubes are lovely.
 
Alan could be talking from the context of his speaker design and the typical mainstream tube amps in the market today. Maybe for speakers like Harbeth, the typical tube amps in the market may not be an ideal solution. Time and again, I have noticed that tube amps should be coupled with speakers that are purpose build for such a design. Otherwise they may sound " nice " but not really ideal if you really crank up the volume and check the sound across the frequency spectrum. However, once I heard Air tight monoblock tube amps with a larger harbeth model and it sounded sublime. Was sitting mesmerized for almost 2 hours in the same spot. The best I have heard Harpeth's sound. Maybe it takes really good design to make it work really well with each other.
 
Incidentally, high sensitivity is a very misleading term....a high sensitivity speaker could present a very complex impedance while a low impedance loudspeaker might be a very benign load. So, as far as tube amps go, "sensitivity" cannot be used as a determining factor for selection of a loudspeaker.
Hi, I did not understand this. Could you explain this a bit more?
I am also trying to figure out the relationship between Resistance load (4 or 8 ohms etc?) and sensitivity (FB/1w/1m?) and how amplifiers respond to these. Is there any online link where this is explained well?
 
Incidentally, high sensitivity is a very misleading term....a high sensitivity speaker could present a very complex impedance while a low impedance loudspeaker might be a very benign load. So, as far as tube amps go, "sensitivity" cannot be used as a determining factor for selection of a loudspeaker.
I agree. The speaker has to be tube friendly from an overall design context. Not just "high sensitivity" although it is one of the most important factor.
 
I've read a lot of his comments over the past year. Without going into his philosophy on electronics (which basically amounts to get electronics that measure good enough and get better speakers), his view on tube amps is a bit more specific. It comes down to the high output impedance of tube amps (relative to solid state amps), which has a measurable impact on the frequency response of Harbeths. He sees this as contrary to the design work that has gone into the speakers.
 
While I am not really someone with any extra love or hatred towards tube or SS designs, personally prefer to stay away from speakers which are so finicky that they specifically wont work with Tubes OR SS.
 
While I am not really someone with any extra love or hatred towards tube or SS designs, personally prefer to stay away from speakers which are so finicky that they specifically wont work with Tubes OR SS.
I think the argument of frequency response changing with impedance would apply to most speakers. Just that most speaker companies are not so outspoken about it. Harbeth users seem to disagree with the company line - the non official user groups are full of amps Mr Shaw would disapprove of
 
I think the argument of frequency response changing with impedance would apply to most speakers. Just that most speaker companies are not so outspoken about it. Harbeth users seem to disagree with the company line - the non official user groups are full of amps Mr Shaw would disapprove of
Thanks ..but why would a designer make a statement like that ? impedance-frequency curves are never a straight line for speakers but just by saying that it wont work might just influence so many folks to even try it !
 
Last edited:
Thanks ..but why would a designer make a statement like that ? impedance-frequency curves are never a straight line for speakers but just by saying that it wont work might just influence so many folks to even try it !
Dont really know. He's been a long time proponent of Quad amps (measure well, good service in the UK). A cynical way to look at it would be to assume he wants people to spend more of their budget on speakers. That may be unfair though.
 
Time and again, I have noticed that tube amps should be coupled with speakers that are purpose build for such a design. Otherwise they may sound " nice " but not really ideal if you really crank up the volume and check the sound across the frequency spectrum.
I agree. The speaker has to be tube friendly from an overall design context. Not just "high sensitivity" although it is one of the most important factor.
Can you please share some attributes of speaker design that if implemented would consider the speakers to be built for tube amplification?
 
Keith, Its like Walking Shoes & Running shoes by Nike .... You can "Just Do It" in either :)
However, the shoe could be made more optimal of the particular task...
So here is my (non comprehensive) list of technical speaker characteristics that I believe would endear them to Valve Power Amplifiers.

* High Efficiency Speakers

* Fairly resistive load

* Speaker Impedance should not vary dramatically (particularly not fall to low values) with Frequency

Since more Tube amplifier users seek "midrange tone," Speakers with a 'Good' Midrange tone would be a good fit
 
Keith, Its like Walking Shoes & Running shoes by Nike .... You can "Just Do It" in either :)
However, the shoe could be made more optimal of the particular task...
So here is my (non comprehensive) list of technical speaker characteristics that I believe would endear them to Valve Power Amplifiers.

* High Efficiency Speakers

* Fairly resistive load

* Speaker Impedance should not vary dramatically (particularly not fall to low values) with Frequency

Since more Tube amplifier users seek "midrange tone," Speakers with a 'Good' Midrange tone would be a good fit
+1
I also remember reading somewhere about SS being a current amplification and Tubes being a voltage amplification and hence how a speaker behaves die to that.
 
I saw this in the Stereophile review of Falcon LS3/5a bookshelves and am mystified. (Happy, but still confused). The magical mystery continues…

Despite its low (83dB/2.83V) sensitivity, it is completely happy with low-power class-A amplifiers—especially tubes.”
The reviewer also notes: It cannot play loud. It compresses macrodynamics., It can sound grainy.

 
I saw this in the Stereophile review of Falcon LS3/5a bookshelves and am mystified. (Happy, but still confused). The magical mystery continues…

Despite its low (83dB/2.83V) sensitivity, it is completely happy with low-power class-A amplifiers—especially tubes.”
The reviewer also notes: It cannot play loud. It compresses macrodynamics., It can sound grainy.


thats why reviews need to be read carefully paying special attention to the lines you mentioned above !! It basically means Dont use low power amplifiers :)

IF I remember right some time back , popularised by Jim Smith, the Harbeth SHL5 with leben 300/600 was known to be the magical combination !!
 
I have run the Harbeths with Electrocompaniet and Quad 909 both SS for a few years before recently moving to tube amplification. I instantly noticed a difference in sound and prefer the tube amp.
The designer and some owners of speakers might want and try to retain a particular flavour/originality they get from the harbeths with suggested amp pairing.
 
I had a similar experience with Harbeths and a few SS amps (Hegel H300, Naim 5i and Atoll IN200). When I paired them with a push pull Tube amp, it was like … aaaahhhh this is just fine. Now I am wondering if a upgrade in the tube amp would be worthwhile.
Alan Shaw (bless him for designing lovely speakers) knows a lot about the subject. But I suspect there may be some bits his strong convictions prevent him from acknowledging. A lot of people in the Harbeth User Group (HUG forum) seem to be pairing Tubes with their Harbeths and loving it.
 
Wharfedale Linton Heritage Speakers in Red Mahogany finish at a Special Offer Price. BUY now before the price increase.
Back
Top