Currently six people I know are building preamps with DHTs as a result
of hearing the difference in their systems.

So do tell me about this 'difference'. Even better, what's the reason
for it ?

You have to hear it - nothing else will enable you to understand what
I'm talking about. We can discuss DHTs but I can't "tell" you what they
sound like.

Andy Evans wrote:

Currently six people I know are building preamps with DHTs as a result
of hearing the difference in their systems.

So do tell me about this 'difference'. Even better, what's the reason
for it ?

You have to hear it - nothing else will enable you to understand what
I'm talking about. We can discuss DHTs but I can't "tell" you what they
sound like.

You can't even begin to describe it ?

Graham

"Eeyore" wrote in
message ...


Andy Evans wrote:

Currently six people I know are building preamps with DHTs as a result
of hearing the difference in their systems.

So do tell me about this 'difference'. Even better, what's the reason
for it ?

You have to hear it - nothing else will enable you to understand what
I'm talking about. We can discuss DHTs but I can't "tell" you what they
sound like.

You can't even begin to describe it ?

Graham


Probably no more than one could describe the sound of a
Bosendorfer concert grand piano to someone who has never
heard one. You need to hear it, Graham.

Iain

Iain Churches wrote:

"Eeyore" wrote
Andy Evans wrote:

Currently six people I know are building preamps with DHTs as a result
of hearing the difference in their systems.

So do tell me about this 'difference'. Even better, what's the reason
for it ?

You have to hear it - nothing else will enable you to understand what
I'm talking about. We can discuss DHTs but I can't "tell" you what they
sound like.

You can't even begin to describe it ?

Graham

Probably no more than one could describe the sound of a
Bosendorfer concert grand piano to someone who has never
heard one. You need to hear it, Graham.

Iain

I'm curious for sure. I'd want to measure it too or would that be some kind of
heresy ?

Graham

I'm curious for sure. I'd want to measure it too or would that be some
kind of
heresy ? Gr

I intend to put the preamps through a whole load of tests when the
prototype is ready. No heresy at all in tests. Andy

In article , Eeyore
wrote:


Iain Churches wrote:


Probably no more than one could describe the sound of a Bosendorfer
concert grand piano to someone who has never heard one. You need to
hear it, Graham.

I'm curious for sure. I'd want to measure it too or would that be some
kind of heresy ?

I'd also be interested in any evidence that it was real, due solely to the
sound, and wasn't something trivial/obvious like an alteration in the
frequency response. IIRC Andy made similar claims a while ago, but although
someone else commented on a possible reason for a different in device
(electronic) characteristics, no-one was able to provide anything more than
assertions of an audible difference that wasn't for a trivial reason.

Slainte,

Jim

--
Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm
Audio Misc http://www.st-and.demon.co.uk/AudioMisc/index.html
Armstrong Audio http://www.st-and.demon.co.uk/Audio/armstrong.html
Barbirolli Soc. http://www.st-and.demon.co.uk/JBSoc/JBSoc.html

"Jim Lesurf" wrote in message
...
In article , Eeyore
wrote:


Iain Churches wrote:


Probably no more than one could describe the sound of a Bosendorfer
concert grand piano to someone who has never heard one. You need to
hear it, Graham.

I'm curious for sure. I'd want to measure it too or would that be some
kind of heresy ?

I'd also be interested in any evidence that it was real, due solely to the
sound, and wasn't something trivial/obvious like an alteration in the
frequency response. IIRC Andy made similar claims a while ago, but
although
someone else commented on a possible reason for a different in device
(electronic) characteristics, no-one was able to provide anything more
than
assertions of an audible difference that wasn't for a trivial reason.


This is interesting - it appears that some here wouldn't necessarily like
what they were eating until they had read the ingredients list on the
packet...???

Andy is building a DHT Pre for me (I don't need to add my own lack of
experience/expertise into the equation and risk crapping up a very sensitive
bit of kit) and the only testing it will get here is a) I got to like it
full stop and b) Swim's got to supply me with a string of 'better' responses
when I get her to hear a various snatches of music over a period of time
with it in/out, amp on its own, amp with Denon's pre section, amp with Pre
vs. another amp on its own &c. &c....

The only thing it won't be directly compared with is my EAR Line Stage -
that's already boxed up for disposal (has been for a few months now) - even
with Mullards in it, Swim could hear if that was in the loop coming up the
garden path!! She never failed to pick up on it!!

It's the old 'proof of the pudding' scenario again, isn't it...??

Andy is building a DHT Pre for me (I don't need to add my own lack of
experience/expertise into the equation and risk crapping up a very
sensitive
bit of kit) and the only testing it will get here is a) I got to like
it
full stop and b) Swim's got to supply me with a string of 'better'
responses
when I get her to hear a various snatches of music over a period of
time
with it in/out, amp on its own, amp with Denon's pre section, amp with
Pre
vs. another amp on its own &c. &c....

I try to get as much feedback as I can for development purposes - you
have to beta test stuff to see where the drawbacks are on other
systems, because your own references can be misleading or atypical.
I've had all my colleagues laboriously listening for hours for
perceived differences, and I'm now putting these DHT preamps in
different systems to see how they sound in other rooms and setups, both
balanced and single ended. So far the DHTs have sounded better than the
preamps they replaced, both active and passive, which is encouraging.
But there are questions, of course. Frequency response is one,
microphonics another (some racks are very resonant, others excellent)
so it's a continued development process.
Last night I took a balanced DHT preamp over to my brothers. He has a
very classy setup - top Krell CD player, big Audio Research tube
preamp, Nagra VPA 845 amps and Apogee Caliper Sigs. Big room. His own
system has a sound which to me is a bit "thick" - lacking transparency
- and also a bit lacking in timbre on instruments, notably woodwind,
cymbals (especially with brushes) grand piano and voice. But it has
generally good "forward" tone and a lot of midrange presence, and the
amp and speakers are superb, better than the front end. The DHT preamp
showed more timbre and better treble and was a distinct overall
improvement, more than subtle but less than overwhelming. This was a
DHT preamp which had a previous version of the filament supply (now
superceded by a better one), so there's room for further improvement.
But better than a big ARC preamp is already a step in the right
direction.
The big change came when we put a Chris Found VDAC-4 digital board into
the system instead of the DAC in the Krell, fed by optical cable from
the Krell transport. Here the sound really opened out and started to
sound very transparent - really as if the hifi wasn't there. Very
natural, like listening to real musicians in the room. The DHT balanced
preamp was developed using this DAC in my system, and is biased to take
the output of the DAC straight into the grids of the DHT. Anyway, this
combination was quite special. My brother intended going to bed early
for an early morning start, but listened for a further 2 hours sitting
with his wife, pulling out CD after CD and listening to track after
track. A recording of a Rachmaninov symphony with Rozhdestvensky and
the LSO was quite gorgeous - rich lush strings, and woodwind plain as
daylight - you could follow the clarinet, cor, flute right through the
tutti parts as well as in solos. I asked my brother what he thought of
the sound - he said "very natural and detailed - better clarity and
instrumental timbre". This is a typical comment - clarity and timbre
are the two most obvious differences. His wife said the same and
clearly preferred it, and she's as (or more) discerning than he is. I
left the DAC and the preamp in his system so he could give me comments
after prolongued listening.
Discussion points: well, basically just frequency response. The bass
was a little lighter, though all there. The midrange was less forward
than before. We discussed whether this was enough to explain the
difference in sound, and we both felt that the difference in timbre of
intruments was too distinct to be explained by frequency response, and
that the clarity, again, didn't sound like a difference in frequency
response. This is a subjective judgement of course.
I don't believe all differences can be explained by differences in
frequency response, though clearly this plays a part. Having heard the
same DHTs in different systems with quite different frequency responses
(one was a big Tannoy system with really fine bass and rather rolled
off treble) I think I can recognise the common factors in the sound -
clarity and timbre. It's a sound that tends to delight classical and
jazz listeners (female vocals with jazz trio sounded spooky - right in
the room) - not sure what it would do for punk and headbangers. The
sound is quite delicate, though fast and foot-tapping.
My favourite rock'n'roll preamp tube is the 1626 ( a nice old ST shape
triode) , which is indirectly heated, but I prefer DHTs for everyday
listening, since my listening is almost all jazz and classical. When I
had my 1626 preamp in the system I used to turn the volume up and put
on Jimmy Smith - you literally felt like jumping up out of your seat
and dancing - it was like being hit by a treble vodka. Horses for
courses! Andy
PS reminds me of one of Ronnie Scott;s comments in his pre-set patter.
"And now I'd like to introduce you to our sound man......... John. John
is our sound man. John is the best sound man in the country. In the
city?............... Useless"

In article , Keith G
wrote:

"Jim Lesurf" wrote in message
...
In article , Eeyore
wrote:


I'd also be interested in any evidence that it was real, due solely to
the sound, and wasn't something trivial/obvious like an alteration in
the frequency response. IIRC Andy made similar claims a while ago, but
although someone else commented on a possible reason for a different
in device (electronic) characteristics, no-one was able to provide
anything more than assertions of an audible difference that wasn't
for a trivial reason.


This is interesting - it appears that some here wouldn't necessarily
like what they were eating until they had read the ingredients list on
the packet...???

Perhaps you should name a few of the "some" you have in mind.

I note that you quote something I wrote and start with "this". But I
neither said, not meant, what you go on say above. If you think so, then
I am afraid you are mistaken. You would also be wrong to think it
must follow from what I said. If you think I am the mysterious "some"
then it looks like our friend the 'straw man' is making another
appearance. :-)

My comments had nothing to do with what anyone might or might not "like"
(i.e. prefer). So I am wondering who you are referring to, and what it
has to do with what I said...

Slainte,

Jim

--
Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm
Audio Misc http://www.st-and.demon.co.uk/AudioMisc/index.html
Armstrong Audio http://www.st-and.demon.co.uk/Audio/armstrong.html
Barbirolli Soc. http://www.st-and.demon.co.uk/JBSoc/JBSoc.html

I'd also be interested in any evidence that it was real, due solely to the
sound, and wasn't something trivial/obvious like an alteration in the
frequency response.

Well, nobody is going to go to the trouble to set up a double blind
test, so that kind of evidence won't happen. I'm not a company with a
testing budget and I don't have time or premeses to set up such things
anyway. I'm just developing stuff, and trying out alternatives at this
stage. The question of frequency response is extremely relevent, but
difficult to do anything about. For a start I don't have a parametric
equaliser of sufficient quality, and even if I did, inserting it in the
chain would change the sound. You get some simple idea of frequency
response in two ways I can think of:
a) Listening on and off axis, in and out of the room
b) Listening to recordings that are bass light and bass heavy
I have to say with the two above, the quality of the sound - especially
instrumental timbre - remains pretty much the same. But your point
about frequency response is quite correct - it has to be factored in.

no-one was able to provide anything more than assertions of an audible
difference that wasn't for a trivial reason. Jim

Correct. Most comments on hi-fi consist of "assertions of an audible
difference". I try to test as logically as I can because I want to know
drawbacks as well as advantages, and I try to test to produce a rank
order with something familiar as reference, and always with known CDs
which have been tried on a variety of systems etc etc. One does what
one can. I'm only interested in the quality of the final sound, and
making design choices on the basis of listening to that sound. I try to
get second and third opinions all the way along to reduce the
subjective element, but I won't compromise the selection of componants
on the basis of the final sound being as close to the original acoustic
listening experience as possible.
Also, I'm not interested in blind tests for the purpose of producing
publications of a scientific nature. I leave that to others. I'm
interested in constantly improving the sound of what I have, and others
judge the results by listening to it directly and not having me
describe it in prose. I'm not unique in this - this is entirely banal
and what I'm sure the majority of small scale hi-fi builders do. And
what sensible hi-fi buyers do - they try a product out in their own
system. If it's better than what they have and affordable they buy it.
If it isn't better they send it back.