Anyone heard of ValveMark amplifiers?
Mal P
their website: www.valvemark.com.au
They have responded to my emails promptly with good information and good
prices for demo models which are just around my budget, however, I can't
find any information about them at all on the net.
Has anyone heard them? Or has any experiences/second hand information about
them? What is the general consensus?
They do have a money back audition guarantee, but I'd be happier trying them
out knowing they were a good company.
Thanks,
Mal
Oscillatus
news:Xns9291BD26A799CO...@210.49.20.254:
> 6 watts f
actually that was 8 watts, even harder to believe
Oscillatus
news:amjr4c$68i4t$1...@ID-106478.news.dfncis.de:
>
> They do have a money back audition guarantee, but I'd be happier
> trying them out knowing they were a good company.
>
Well, I worry about their claims. Example, how do they get 6 watts from a
6A3 SET ? Normally, the 2A3/6A3/6B4G equivalents atre good for 3.5 watts
only. (other claims also seem a bit ambitious)
Mal P
news:Xns9291BD26A799CO...@210.49.20.254...
Ahh, dubious power ratings, first sign of cracks... how about the KT90, what
watts can you get out of that one? (any replacements available for it, apart
from in Yugoslavia?)
Thanks,
Mal
Patrick Turner
Mal P wrote:
The KT90 is a nice choice of tube for a SE amp.
It has an anode dissipation rating of about 45 watts,
and so if it is used in pentode mode,
and efficiency is 35% in class A, then 15 watts is available.
However, 10 to 12 watts is also available from 2 x KT88,
and these are more readily available, cheaper, and probably longer lasting.
The best way to get good power and low thd from such tubes in pentode,
is to use the acoustic connection, ie, have about 20% of the OPT primary winding
devoted to a cathode feedback winding.
The screen can be taken to a fixed voltage a good % lower than the anode supply
voltage.
About the same power output is available as normal pentode mode without
the CFB winding, but the thd is lower than triode mode.
Because transformers for this are not available ready made,
triode connected KT88, or KT90 can be used, which gives
from 8 to 9 watts output.
Two paralleled tubes give 16 to 18 watts in triode,
and with some extra global NFB of about 12 dB, the sound at a
watt or two will be quite superb, accurate and detailed.
I don't know where to get KT90.
I would try for 2 x KT88.
3.5 watts from a 2A3/6A3 is the correct power output rating in the data books.
For speakers rated at 90 dB/w/M, 3.5 watts is, IMHO, too low,
and the amp just won't give you the luxury of turning up the volume
and being able to cope.
Patrick Turner.
Mal P
> For speakers rated at 90 dB/w/M, 3.5 watts is, IMHO, too low,
> and the amp just won't give you the luxury of turning up the volume
> and being able to cope.
How about 8 watts, from say the 300B? On 89dB/w/M speakers, that would mean
a 'theoretical' max headroom of around 98dB, which is certainly a lot more
than what I listen at (I measured my average listening levels at my chair,
3m away... 75-80dB, with 85-90dB peaks).
Thanks,
Mal
Patrick Turner
Mal P wrote:
I still think 8 watts is too low with 89 dB speakers, IMHO.
I have 5 watt SE amps in an old high quality tubed AM/FM reciever here.
These amps would do justice to the quality of the music from the rest of the
radio set only if the speakers were over 95 dB efficiency,
or I only needed quiet background music.
I like classical, and on my speakers where its just one violin one minute, the
5 watt amp
copes OK, but when the whole orchestra booms away, the sound goes muddy.
I have used 15 watt amps on speakers of 93 dB, and that restricted the volume
somewhat sometimes.
Its only my opinion, but I find about 25 watts is the bare minimum
for my 90 dB speakers.
The reason is mainly that I feel the majority of what I listen to
is then covered by the "sweetzone" of the tube amp.
This is the first few watts where the distortion
is entirely negligible, and all the subtleties and detail
of the recording are revealed, such as the natural warmth of massed strings,
the pizazz of brass, the forment in the voice of singers, including
strident female types, without glaze, burriness, smear,
and amalgamation of instruments and poor imaging.
An 8 watt amp of any type would be a serious compromise for me,
but not for the guy with speakers of 96 dB/w/M.
Such speakers need only 1/4 of the power I say is my minimum.
For every +/- 3 dB of SPL produced by a speaker,
a doubling of halving of power is required.
I sometimes drive or walk past houses where the sound I hear
must obviously be averaging 90 dB in their room, and peak levels might well be
106 dB, so I guess if their speakers are 90 dB, for 1 watt, 20 watts
will allow this.
But for real world reliability, 50 watt amps might suffice.
I would think that sustained 90 dB average levels
would cause premature hearing damage.
Nearly everytime I hear such a row coming from a residence, its
pounding rock music, with not much hi in the fi.
At a meeting today with a client and a friend,
we found the loudest we could take it without wanting to get outa the house
was when the SPL meter we had read 94 dB at a meter from one of the two
speakers.
The speakers were Vaf, with a claimed 95 dB efficiency, and the
85 watt PP tube amp used was only having to make about an average
1 watt to produce this never used SPL.
But at 1/4 watt, the listening was superb, and levels way way away from
clipping,
or any other detectable artifacts which might have degraded the sound.
The client needs an amp which will effortlessly
cope with his every whim, AND allow for
future use of lower sensitivity speakers, or future resale
to somebody with lower sensitivity speakers.
If money is to be spent on one's hobby, ( since it isn't an investment ),
then at least what is spent should not be thrown away,
if circumstances change, and you need to sell your amps.
It will move the time when you feel you need to upgrade
further out into the future,
because you won't hear anything better for an awfully long time.
Patrick Turner.
>
>
> Thanks,
> Mal
TG
some years and as far as I know are a reputable company - I've certainly never
heard any complaints about them. I believe the website is a comparatively
recent move.
I contacted Igor about 3 years ago when I was first getting interested in valve
amplification and he responded promptly with plenty of good information. I
can't speak about the quality of his products as I never followed up on the
enquiry, however his 14 day trial offer is very generous. Some of the claimed
power outputs might only be realised at higher distortion levels - 10 to 12
watts from a single ended 300B sounds a little much to hope for - but to be
fair he's not the only dealer to be "optimistic" about his specs, Cary amps
have a fine reputation but also are known for speccing power output at >5% THD.
The prices compare favourably with overseas products and it's interesting to
see that he's now offering his schematics and construction notes for sale to
DIYers, although I can't comment on how original or innovative his designs may
be as I've not seen this material. They may be brilliant or simply variations
on well known topologies.
Hope this helps
TG
Mal P wrote:
--
------------------------------------------------------
Anthony Green - Language Centre Librarian
University of Sydney Language Centre
Room 211, Christopher Brennan Bldg (A18)
University of Sydney NSW 2006 AUSTRALIA
Tel: +61-2-9351-6780
Fax: +61-2-9351-3626
anthon...@language.usyd.edu.au
http://www.arts.usyd.edu.au/Arts/departs/langcent/
------------------------------------------------------
Jeremy
> It's a company here in Australia that sells affordable SET amplifiers via
> their website: www.valvemark.com.au
<homer> mmmmmm.... 6C33C-B </homer>
Ah... the last piece falls into place.
I've seen their ads in Australian HiFi but could find nothing else
about them.
I think that means that all of the Australian manufacturers who
regularly advertise in the various print magazines now have websites.
Jeremy
Dale
dale
"Jeremy" <everyone...@freemail.com.au> wrote in message
news:7825cc83.02092...@posting.google.com...
Oscillatus
The problem I have with 300B's is the ripoff prices they are going for. I
think Pat is right that with low efficiency speakers, you need a bit better
than the 3.5 watts of 2A3 types. 8 to 10 watts from an EL34 SE amp of mine
is OK though, and the sound is nice.
Oscillatus
news:3D8DAF36...@turneraudio.com.au:
>
> It has an anode dissipation rating of about 45 watts,
> and so if it is used in pentode mode,
> and efficiency is 35% in class A, then 15 watts is available.
yes, and there claim of 25 watts smells on this one too.
Phil Allison
** A class A amp can run higher than usual power if you never let it
idle. The worst heat dissipation is when it is at idle.
So maybe you gotta let 'em really rip!!
Regards, Phil
Oscillatus
news:WGzj9.38303$g9.1...@newsfeeds.bigpond.com:
>> >
>> > It has an anode dissipation rating of about 45 watts,
>> > and so if it is used in pentode mode,
>> > and efficiency is 35% in class A, then 15 watts is available.
>>
>> yes, and there claim of 25 watts smells on this one too.
>
>
>
> ** A class A amp can run higher than usual power if you never let it
> idle. The worst heat dissipation is when it is at idle.
>
>
> So maybe you gotta let 'em really rip!!
Yea right. No way they really get that useable power from that tube for
any extended length of time.
Phil Allison
** I suspect it is a naughty peak power figure - no sign of the "rms"
term to be seen or any THD figures.
Someone ought to bite the bullet and email them for an answer!
Regards, Phil
Mal P
> Valvemark have advertised through the local Australian "Hi-Fi" magazine
for
> some years and as far as I know are a reputable company - I've certainly
never
> heard any complaints about them. I believe the website is a comparatively
> recent move.
And a good one too... they advertised on Google which is how I found them,
so net advertising sometimes does work!
> I contacted Igor about 3 years ago when I was first getting interested in
valve
> amplification and he responded promptly with plenty of good information.
Yes, he is quite detailed about his responses and the pride that he has in
his products.
> can't speak about the quality of his products as I never followed up on
the
> enquiry, however his 14 day trial offer is very generous.
Alas, the $80 shipping each way (so $160 to audition) pretty much kills my
chances of just auditioning.
> Some of the claimed
> power outputs might only be realised at higher distortion levels - 10 to
12
> watts from a single ended 300B sounds a little much to hope for - but to
be
> fair he's not the only dealer to be "optimistic" about his specs, Cary
amps
> have a fine reputation but also are known for speccing power output at >5%
THD.
He actually stated 8 watts in an email from the 300B, maybe his website
information is there to suck people in at first ;)
> The prices compare favourably with overseas products and it's interesting
to
> see that he's now offering his schematics and construction notes for sale
to
> DIYers, although I can't comment on how original or innovative his designs
may
> be as I've not seen this material. They may be brilliant or simply
variations
> on well known topologies.
I would very much like to hear them, but without much user feedback and
without knowing much about them, it's hard for me to pay the cash to
audition (have to buy first and then get refunded).
Thanks TG,
Mal
Mal P
> The problem I have with 300B's is the ripoff prices they are going for. I
> think Pat is right that with low efficiency speakers, you need a bit
better
> than the 3.5 watts of 2A3 types. 8 to 10 watts from an EL34 SE amp of
mine
> is OK though, and the sound is nice.
Yes, I'm thinking 8 watts should be ok... I measured by comfortable
listening levels today again, and the absolute maximum the volume hit on my
most dynamic recording is 90dB... easy for an 8 watter running 89dB
speakers. Maybe 16 would be good to have the headroom though.
Say, you wouldn't want to build me one for cheap would you? ;) What are your
amps like? Any pictures?
Btw, how much does the 300B tube go for in Aus?
Thanks,
Mal
Patrick Turner
Oscillatus wrote:
The best SE sound comes when you are in the SE sweet gold operation zone,
and stay within that for most of the listening.
This means having more power than you figure you can pay for right now,
or more than you think you can get away with.
That's why when I made my SEUL amps, I reckoned
20 watts minimum for me, and to show I might not need
an Ongaku 211 amp, or whatever.
The costs in making some SE 20 watter is the same for making
a 75 watt PP amp with say two KT88.
Scaling down to 50 watt PP with EL34, the only
price difference is the tube cost.
I would rather have KT88, ( or 6550 ) instead of EL34, any day, because
it gets back to what I said before, that effortless authoritive sound,
not marred by any artifacts.
The cost of the tubes is a small % of the total amp cost.
But 40 watts is plenty, and if 2 x KT88 PP are used, it can have
a high % of class A.
the same 2 x KT88 can give about 12 watts each for 24 watts total,
in pentode mode, or 16 watts in triode.
The cost of the 2 x KT88 is less than one 300B.
The only thing that might puzzle anyone is the sound difference.
I see no reason why there would be much difference
if either tube is set up well, and used at sensible power outputs.
People say paralled tubes are not optimal, or that the sound is worse,
but I have heard from experience that the opposite is true,
and I have just made PP amps with 12 x 6550 and the parallel
tubes sound no worse than 2 x 6550, at a couple of watts.
Patrick Turner.
Patrick Turner
Oscillatus wrote:
It is utterly impossible to achieve an efficiency greater than
50% with any pure class A amp.
So if 45 watts of anode power is the input power at idle,
then the theoretical power output is 22.5 watts max, which
you will never get, unless the tube was a perfect device, which it
isn't,
like bjts and mosfets.
The reason is that the anode voltage swing is limited by the
the tube characteristics, and 35% is a more reralistic efficiency
figure for class A pentode.
35% of 45 watts input power is 15 watts output power,
allowing for some 5% losses in the OPT.
But tht's OK, running an SEP KT90 is about like running a 75 watt
light bulb,
and have you done a count on the lightbulbs in the house?
The KT90 should give around 12 watts SET, and two should give 24
watts.
But I don't think they are being made anymore,
so I would rather use KT88, 6550.
Patrick Turner.
Patrick Turner
Mal P wrote:
There are a few amp pictures at the website.
Prices are attatched.
Unfortunately, I cannot compete with the prices for
some chinese and some russian amps, but
I do wonder at the inner build quality.
Many things are made OS using cheap labour,
and as you know, a bowl of rice and glass of water costs more
here in Oz than elsewhere.
300B probably will never be my choice of tube.
I can get a 13E1 or 2 x KT88 which makes 20 watts for
the same price as a 300B, which brings a high price, because
so many like the sound, AND, it is flavour of the decade, ie fashionable.
Many other unfashionable tubes are just as good to use, IMHO.
And from all reports, the unfashionable tubes for SE, ie, KT88,
are far more reliable than 300B.
The cathode of the 300B is its weak point.
I really don't know why the guys in the tube factories don't just make a
real triode using the KT90 glass and anode structure, with an octal base,
or a 300B with an indirectly heated cathode, and octal base.
If they did that, it would be highly successful for them.
Patrick Turner.
Oscillatus
> Yes, I'm thinking 8 watts should be ok... I measured by comfortable
> listening levels today again, and the absolute maximum the volume hit
> on my most dynamic recording is 90dB... easy for an 8 watter running
> 89dB speakers. Maybe 16 would be good to have the headroom though.
>
> Say, you wouldn't want to build me one for cheap would you? ;) What
> are your amps like?
Butt ugly. I build for myself only (not legal to build and sell - too much
paperwork and licences etc), usually on old recycled chassis. My favourite
2A3 type is on an old 1940's PA amp chassis, and I re-used it's old power
transformer and PS choke. Iron is the expensive bit, and just ask Patrick
how much good output trannies cost. Even cheap 'good' ones, will set you
back about $200 each. Mind you they can still sound really fine.
Check out the kit amps from Bottlehead though. The simple approach appeals
to me.
>Any pictures?
I wouldn't dare :-)
>
> Btw, how much does the 300B tube go for in Aus?
$300 to $600 for a matched pair of new ones, but for old NOS, well, the
sky's the limit it seems :-)
Patrick Turner
Oscillatus wrote:
The 300B is the most overated tube in the world of tubes.
Fair dinkum, its over priced.
For $300, I can get 4 x KT88 which will give a total of 50 watts. SE.
Compared to 2 x 300B, with total 16 watts, there is no value in 300B.
The 300B should be no more to buy than KT88.
Its only got 3 elements in it, not 5.
But the world of supply, demand and fashion means
you gotta pay for 300B, and retubing in a few years is rather painful.
I bet the KT88 will last longer than the 300B.
Some people say using tetrodes or pentodes
wired as triodes will not sound as well as real triode tubes.
Over a period of 5 years, I have demoed my 13E1 SEUL amps to a lot of
people, and never had a bad report, in fact, they like the sound more
than the best of my PP amps.
The 13E1 is a beam tetrode, rigged up with an ultralinear screen tap at 66%
of the total anode primary winding.
This way I eliminate nearly all the odd order thd, and the spectral content is
nearly identical to pure triode connection.
Recently I experimented using 6550 beam tetrodes in PP amps
set up as in Quad II with CFB windings on the OPT,
but with a lower screen supply voltage.
The thd fell 10 dB lower than when UL is used.
The "distributed load", ( ie CFB windings al la Quad II work better than plain
UL.
So I think now a SECFB output stage will perform better than
any UL or triode stage, if the % of CFB is about 16%.
The use of KT88 in a SE amp with CFB will require only about
60 vrms drive voltage to the output grids, still low enough
for driver tubes like the 6SN7 to be able to easily make with low thd.
Its easy to get 8 watts from one KT88 in SET,
But in pentode + CFB, maybe 13 watts is available,
so two working together are ideal.
Patrick Turner.
Paulp
I only know of Valvemark amps through a guy who works at the local HI-FI
store, who owns some of Igor's epuipment (not sure what though). He gave
positive feedback about the amps and suggested I contact Igor. At the time
there was no web site so I couldn't get any other information.
The positive thing about this was that the store doesn't sell Valvmark
equipment or any valve equipment for that matter and he has worked at the
store for 8-9 years that I know of.
Happy hunting
Paulp
Craig Brown
another listen the day after, to a second hand unit , and had the chance
to compare it to a second hand Contan and an older Luxman(valve). The Luxman
was the pick of the bunch for me. Don't recall the model as Valvemark make
several and will make anything you want. Some of the monoblocks look
interesting. I've seen a couple kicking around second hand. I Think Simply
HiFi had one.
Igor does seem to be the sort of bloke that will stand by his product and
back it up with good service.
"Mal P" <pandor...@hotmail.com> wrote in message
news:amjr4c$68i4t$1...@ID-106478.news.dfncis.de...