Which 12AU7?
Tim
From: Cheung Kam Lau <b41...@mailserv.cuhk.edu.hk>
To: <timoth...@hkmensa.org>
Sent: Wednesday, 15 September 1999 11:21
Subject: Which 12AU7 to buy?
> Tim,
> I am ROM member of the forum.NO posting allowed so I have to ask
privately.
You are now. Welcome to our club!
> I am a friend of John and Lee HC. Hope you don't mind sharing your
views on
> which 12AU7 to buy. My system comprise of Jadis DPL, Defy 7, to drive
Martin
> Logan Quest-Z (electrostatic panel),with passive bi-amp using Aragon
> 4004MKII to drive the woofer( <180Hz). My music taste is mainly
strings and
> vocals, and looking for full- body, warm vocals/violin with details.
Wonderful system. I like the Defy 7 a lot and what a powerful amp! Is
the 4004 really needed?
> I am
> trying to re-tube the stock 2 ECC82, 1 ECC83 in the DPL, and 2 ECC82,
4 ECC
> 83 in the Defy 7. Which ECC82 is good to buy?
I am not too familar with the circuit of DPL (SRPP?) but I always
observe that the "last" tube in the pre-amp is the most important tube
to upgrade and also where you should spend most money. For the power
amp, it is the other way round and it is the "first" tube that is most
sensitive to upgrade. And tube selection is an interesting game. There
is no absolute rule and you may have to try different combination for
best result (e.g. what Andy is doing with different 6SN7).
We have tested 6SN7, ECC83, ECC88, and to some extent ECC81 in tube
party in the past but never got round to ECC82. We should do that soon.
The best sounding 12AU7 I heard is the TFK 802S, but I have since
acquired 10M 12AU7, Gold Lion B749, Amperex BB 7316, and long plate
Mullard which are supposed to be as good but I have never auditioned in
detail.
But I think the best buy of 12AU7 has to be a Gold Arrow platinum grade
12AU7 possible made by RT in German. It is 80% as good as 803S but
maybe 1/3 its price.
>Is $500 too expensive for a Mullard longplate?
No, if it is new-in-box.
> How is this compared to Telefunken? please give some
> guideline to buy.
TFK 12AU7, like their 12AX7, is a "benchmark" tube but it is not
particularly good. And it tend to work to some system but not on other.
It is quite weak in the bottle-end too. Mullard long plate is much
better IMO.
> Last week, I got a pair of Bugle Boy U7 at $100 each, but they sound
no
> difference to my JJ Tesla 802S in the driver stage.
Amperex BB 12AU7 with D-getter long plate is clearly a RR grade 12AU7
and is expensive. The $100 BB U7 must be very late model and I am not
surprise it is not making much difference, particular in the driver
stage.
Maybe we should have a tube party with your gear to find out what 12AU7
is/are the best.
Tim
Sent via Deja.com http://www.deja.com/
Share what you know. Learn what you don't.
wilso...@my-deja.com
I would like to share my experience to you. I was tested the ECC82 in my
DIY pre-amp in non-feedback design last night. So, the result should be
quite ture.
1) Brimar CV4068 three star
2) 7316 BB long plate version three star ( due to the tubes is weak)
3) BB 12AU7 long plate version D shaped getter with support 4 star
4) BB 7316 short plate version D shaped getter( rare tube) 5 star
5) Philips made in Holland CV491 long plate D shaped getter without
support(2nd generation rare tube) 5-1/2 star
6) Mullard long plate square ring getter 6 star
My friend also has a good experience on the BB 7316 in his Jadis pre-amp
which is using ECC82 + 3 ECC83(I don't know the model name). He told me
it was better than Tele ECC82.
I found the my friend Jadis pre-amp is a bit roll off on the high
frequency. I guess your pre-amp also the same. So, you could try BB
short plate big ring getter or any long plate ECC82. Another good ECC82
is RT 12AU7s. No ECC82 in the world can beat the high frequency of
the RT 12AU7s. One of my tube collector friend has bought 12 pcs in his
collection. Mullard ECC82 long plate is also good, however, that is my
bias taste.
Have fun !
Wilson
In article <7ro258$93m$1...@nnrp1.deja.com>,
epie...@my-deja.com
recommend you to look for a tube call "hivac" CV491, which, from my
personal experience, probably has the sweetest sound stage among all the
12AU7 I tried. It comes with a long black plate with an exceptionally
small horse-shoe shape getter. This is a ultra rare tube and I can
provide you a photo on net if you need.
If an appreciation of 12AU7 to be launched, here is a list of tubes that
you can try:
Amperex Bugle Boy long plate D getter 12AU7
Amperex holland long plate D getter CV491
Amperex long plate D getter 7316
Amperex short plate D getter 7316
Brimar Laboratory sample black plate square getter 6067
Brimar black plate square getter 12AU7
Genalex Gold Lion B749
Genalex Gold Monarch B749
Hivac CV491
Mullard Black long plate square getter 12AU7
Mullard Grey long plate square getter 12AU7 (3 versions to be selected)
Marconi/GEC/Osram long plate square getter B329
Mullard Toast plate square getter 6189
Mullard 10M gold pins 12AU7
Reytheon gold pins 7730
RT long plate 12AU7
Siemen E82CC
Telefunken ECC802s
Tunsol smoky glass blk plate 12AU7
I have my listening already and hope to hear your result in the oming
future
Creevy
In article <7ro5d9$big$1...@nnrp1.deja.com>,
cheu...@my-deja.com
I am overwhelmed by so many types of 12AU7 suggested.Where to find
these oldies tubes? As a late starter in the fantasy world of tube
gears, I am totally confused in the tube shops.One good tube in this
gear may not be good in the other. But the fun in tube gears is you can
swap tubes to make the sound for your taste. I am still waiting for my
TFK 12AX7 and U7 to arrive. HC once tell me that we should avoid using
same type of tubes in the amp. What's the theory behind it? I thought
they should match better.
As for my gears, I like orchestral works and violin/cello pieces.
That's why I waited for 3 years till the ML quest-Z was on sale few
months ago. The shop was shut down in Ocean centre after I bought them!
The open sound stage and mids is stunning compared to my MF MC-6
before. But later,all my violin CDs sound squeaky in the top. Finally,
I switched to all tube amps which bring me close to the real music.(I
played trumpets in school and a tenor in the choir,so my ears are
trained). But the bottom bass is woolly and weak. So I bi-amp the Quest-
Z, which is a hybrid of 2 very different speakers anyway.
Will let you know after I changed the X7 and U7s.
Best regards.
KL
jekyl...@my-deja.com
You should thank me for telling Tim who you are!
> I am overwhelmed by so many types of 12AU7 suggested.
This depends on your perspective. You are listening to a bunch of
obsessives.
If I were you, since you have the Tele's coming, I will just stick with
those. There's little point to buy all those expensive tubes. You will
soon be able to buy another preamp for the money and that will make
more difference than tube change.
If treble is needed I agree with Wilson that RFT is cheap and good in
this respect.
You may not know that I have the Jadis DPL2, which is not quite the same
as the DPL (less tubes and regulation). It uses 1xU7 and 1xX7. You know
what U7 and X7 I am using that gives me the best result? An RCA black
plate D-getter 6189 (equivalent of U7) and RCA 7025.
The Euro people, and the tube sellers, know SO little about US tubes.
Time for a U7 shootout.
--
Used to be doctorjohn, now Jekyll and Hyde
cheu...@my-deja.com
Is this the RFT made by the previous East Germany? Please tell me what
role is the U7 and X7 in DPL2 for? I believe the 2 U7s is for voltage
output and the X7 is functioning as twin triode in signal amplication.
Am I correct? How can I know,by the look, what is a D-getter?
KL
diy...@my-deja.com
plate load with buffer out circuit, and use triodes in parellel.
If you believe that single plate 2A3 is better than the double plate
ones, you won't agree with that triodes in parellel.
Diytfy!
Tim
jekyl...@my-deja.com wrote:
> In article <7rsebh$gji$1...@nnrp1.deja.com>,
> cheu...@my-deja.com wrote:
> > Thank you Tim for letting me in.
>
> You should thank me for telling Tim who you are!
>
> > I am overwhelmed by so many types of 12AU7 suggested.
>
> This depends on your perspective. You are listening to a bunch of
> obsessives.
That is actually quite true. Most of those 12AU7 listed are for serious
tube collector and not available from any tube shop in the world!
> If I were you, since you have the Tele's coming, I will just stick
with
> those. There's little point to buy all those expensive tubes. You will
> soon be able to buy another preamp for the money and that will make
> more difference than tube change.
That is the view from a metal addict instead of a tube junkie.
> If treble is needed I agree with Wilson that RFT is cheap and good in
> this respect.
This is one 12AU7 which mosy agree is a good buy. I think the Gold
Arrow was actually a RFT instead of RT.
> You may not know that I have the Jadis DPL2, which is not quite the
same
> as the DPL (less tubes and regulation). It uses 1xU7 and 1xX7. You
know
> what U7 and X7 I am using that gives me the best result? An RCA black
> plate D-getter 6189 (equivalent of U7) and RCA 7025.
>
> The Euro people, and the tube sellers, know SO little about US tubes.
> Time for a U7 shootout.
Is there any need to know Skoda when there are RR, BMW and even Civic
out there?
Tim
cheu...@my-deja.com wrote:
> Thank you Tim for letting me in.
> these oldies tubes?
I think you can find some of the 12AU7 mentioned in the post from me
and Wilson. I do not think you can find any 12AU7 listed by Creecy
dispite the very long list!
> As a late starter in the fantasy world of tube
> gears, I am totally confused in the tube shops.One good tube in this
> gear may not be good in the other. But the fun in tube gears is you
can
> swap tubes to make the sound for your taste. I am still waiting for my
> TFK 12AX7 and U7 to arrive. HC once tell me that we should avoid using
> same type of tubes in the amp. What's the theory behind it? I thought
> they should match better.
I think the reason why HC said that is because many tube brands, like
TFK and Mullard, have a very strong tonal character across the whole
family. So unless your system is not very balanced from the beginning,
using 12AX7 and 12AU7 from the same brand e.g. TFK may over-emphasis
this brand character particularly for current production amp. It is as
not much of a problem from some vintage amp as some may have
designed/tuned with all-TFK or all-Mullard setup.
TFK and Mullard have very different and almost opposite tonal
character. And mixng them up could well achieve the most balanced
sound! I think Chek Yie, in his article in Aduiophile, on Gold Lion
B7x9 (super grade 12AT7/U7/X7 made by Mullard) and TFK ECC80xS (super
grade 12AT7/U7/X7 made by Mullard) series of tube, mentioned he got the
best result when he mixed the two series together. I also found the
best tube combination on my Matisse Atom to be Mullard M8162 gold pin
(super grade 12AT7) with TFK ECC803S (super grade 12AX7). And Lee HC
got the best result mixing TFK ECC801S with Tungsram ECC83 silver
instead of all-TFK setup.
> As for my gears, I like orchestral works and violin/cello pieces.
> That's why I waited for 3 years till the ML quest-Z was on sale few
> months ago. The shop was shut down in Ocean centre after I bought
them!
> The open sound stage and mids is stunning compared to my MF MC-6
> before. But later,all my violin CDs sound squeaky in the top. Finally,
> I switched to all tube amps which bring me close to the real music.(I
> played trumpets in school and a tenor in the choir,so my ears are
> trained). But the bottom bass is woolly and weak. So I bi-amp the
Quest-
> Z, which is a hybrid of 2 very different speakers anyway.
I see. Well, driving hybrid speaker is indeed a tricky act!
wilso...@my-deja.com
Tim <tyy...@hkstar.com> wrote:
> In article <7rsebh$gji$1...@nnrp1.deja.com>,
> cheu...@my-deja.com wrote:
> > Thank you Tim for letting me in.
> > I am overwhelmed by so many types of 12AU7 suggested.Where to find
> > these oldies tubes?
>
> I think you can find some of the 12AU7 mentioned in the post from me
> and Wilson. I do not think you can find any 12AU7 listed by Creecy
> dispite the very long list!
Maybe, we tell him too much information. I sugguest you to buy a pcs of
Mullard long plate tubes(warm sound & musical) & a pcs of Bugle boy long
plate to test. Then you will have Mullard, Amperex & telefunken to test.
Three of the tubes are a good tubes. After you made a listening test,
you would know what was your preferance. And I think collect those tubes
is just a basic tubes collection for every tube lover. The money, you
can't save.
Have fun!
Wilson
cheu...@my-deja.com
plate Mullard U7? What is D-getter? some say round or square one? Any
suggested idiot's guide for choosing U7? Tim, Can you make a photo
album of these esoteric tubes for the tube connoisiuers around the
world? This will ceratinly make our forum famous!!
Furthermore, which local tube shop is more realiable, Full Range, Lai
Shan,Wi Wi,YK, LTCMD....? God, More difficult than Bordeaux wine!!!
I 'd better concentrate on the music after reading my bank statement.
KL
Tim
cheu...@my-deja.com wrote:
> Thanks for all the inputs. Can someone tell me how to pick a real long
> plate Mullard U7? What is D-getter? some say round or square one?
To identify a real Mullard is not too difficult. All real Mullard has a
6 or 7 digit 2-row sand-blast code etched on the glass envelope. The
only thing is that Amperex Holland also has a similar 2-row sand-blast
code. But all Amperex code has a triangle symbol at the beginning of
the 2nd row.
And long plate is 17mm long. So if it is a real Mullard and has the
long plate, it is a Mullard long plate. Not difficult at all, right?
Getter is more difficult and that is why there is a whole body of
knowledge in tube collection call "getterology"! For most purpose, you
can treat square getter and D-getter to be the same thing. It is only
that some such getter are more like a "D" and some more like a square.
As far as they are not a complete circle, it is a D or square getter.
For almost all NOS European tubes, sqaure/D getter is older than large
round getter which in turn is older than smaller round getter.
The other key feature in identifying NOS tube is the getter support.
There are the single support vs. double support, ribbed support vs.
smooth plate, rectangular support vs. trapezoid support, inclined
support vs. non-inclined support, copper support vs. non-copper support
and long support vs. short support vs. no support, etc.
> Any
> suggested idiot's guide for choosing U7? Tim, Can you make a photo
> album of these esoteric tubes for the tube connoisiuers around the
> world? This will ceratinly make our forum famous!!
I have been thinking about doing that for the last 2-3 years. Just need
some help to set up the on-line photo album. Alfia has even suggested a
hard cover publication!
> Furthermore, which local tube shop is more realiable, Full Range, Lai
> Shan,Wi Wi,YK, LTCMD....? God, More difficult than Bordeaux wine!!!
> I 'd better concentrate on the music after reading my bank statement.
That is the big problem. As I mentioned before, we should not rely on
the seller. If we know the tube well, it is less easy to be fooled by
them.
Tim
am...@my-deja.com
With your knowledge in small tubes and power DHT, you should publish a
tube guide on "Audio Tube identification", if you need any help in
photographing the tube, please let me know .
Regards, Alfia
In article <7rv7fk$fes$1...@nnrp1.deja.com>,
diy...@my-deja.com
In article <7ruuhp$9rs$1...@nnrp1.deja.com>,
cheu...@my-deja.com wrote:
> Thanks for all the inputs. Can someone tell me how to pick a real long
> plate Mullard U7? What is D-getter? some say round or square one? Any
> suggested idiot's guide for choosing U7? Tim, Can you make a photo
> album of these esoteric tubes for the tube connoisiuers around the
> world? This will ceratinly make our forum famous!!
> Furthermore, which local tube shop is more realiable, Full Range, Lai
> Shan,Wi Wi,YK, LTCMD....? God, More difficult than Bordeaux wine!!!
> I 'd better concentrate on the music after reading my bank statement.
>
> KL
>
I have very good experience to replace 12AU7 with 12BH7 if you filament
supply is enough. I had some null black plates D-getter very old 12BH7
few $ each from ebay. When I replaced and adjust the bias, the 'Mullard
toast plate cv4003' and 'Square getter RCA clear top' becomes toys.
Does it mean that longer the plate, better the sound? 12BH7 has a plate
length over 20mm & consume double filament current.
Hv diy fun!
Diytfy
jekyl...@my-deja.com
wilso...@my-deja.com wrote:
> Maybe, we tell him too much information. I sugguest you to buy
> Mullard long plate tubes(warm sound & musical) & a pcs of Buglelong
> plate to test. Then you will have Mullard, Amperex & telefunken
> Three of the tubes are a good tubes. After you made a listening test,
> you would know what was your preferance.
Sensible.
--
Used to be doctorjohn, now Jekyll and Hyde
Tim
am...@my-deja.com wrote:
> Tim,
> With your knowledge in small tubes and power DHT, you should publish a
> tube guide on "Audio Tube identification", if you need any help in
> photographing the tube, please let me know .
>
> Regards, Alfia
I definitely need help with photography as I know nothing about this and
only brought my first "fool" camera 2 years ago!
I think the main problem is lighting as we need to show the top getter
structure and all that. Can we use digital camera directly or SLR with
all the fancy filter lens?
Maybe we should set up a day to photograph my entire tube collection.
Tim
am...@my-deja.com
I have done some testing with my 6922 under normal room lighting
condition (no flash light) and that turns out very good with my digital
camera.
Thanks, Alfia
In article <7s4ccr$olh$1...@nnrp1.deja.com>,
reylon...@my-deja.com
on this subject.There is an interesting article in a Sound Practices by
Bruce Berman-that ties in with my experiencs with the 12AU7.Writing
about his homebrew 76 line stage,he states that every 12AU7 that he has
ever heard,imparts a sleepy quality to the music.The concensus,seems to
be -substitute a 6CG7/6FQ7 for all 12AU7s taking care to change
appropriate resistors and making sure that the gain does not change.My
experience mirrors this approach-as far as the sleepiness of the
12au7,including TFKs.Best,Raanan
jekyl...@my-deja.com
reylon...@my-deja.com wrote:
>My
> experience mirrors this approach-as far as the sleepiness of the
> 12au7,including TFKs.Best,Raanan
I can understand why people say that. The U7 has a really mellow sound,
compared to the X7 and T7.
--
Used to be doctorjohn, now Jekyll and Hyde
Tim
> on this subject.There is an interesting article in a Sound Practices
by
> Bruce Berman-that ties in with my experiencs with the 12AU7.Writing
> about his homebrew 76 line stage,he states that every 12AU7 that he
has
> ever heard,imparts a sleepy quality to the music.The concensus,seems
to
> be -substitute a 6CG7/6FQ7 for all 12AU7s taking care to change
> appropriate resistors and making sure that the gain does not change.My
> 12au7,including TFKs.Best,Raanan
No, I mean that observation about the sonic character of 12AU7 is true.
But I think that is also the very reason why 12AU7 is used (instead of
12AX7) i.e. to tame the sound of a system that may otherwise be too
aggresive! For example, many Marantz 7 variants use the 12AU7 at the
output buffer instead of the 12AX7 in the original design.
Tim
wilso...@my-deja.com
>
> I have very good experience to replace 12AU7 with 12BH7 if you
filament
> supply is enough. I had some null black plates D-getter very old 12BH7
> few $ each from ebay. When I replaced and adjust the bias, the
'Mullard
> toast plate cv4003' and 'Square getter RCA clear top' becomes toys.
> Does it mean that longer the plate, better the sound? 12BH7 has a
plate
> length over 20mm & consume double filament current.
>
> Hv diy fun!
> Diytfy
>
Hi DIYTFY,
I also agree with you on this point. I found 12BH7 was better than 12AU7
for the buffer application according to the DATA sheet. It is higher
current, higher heater current, lower output impedance & higher power
handling. ANd I also found 6BX7 & 6H30 was even better than 12BH7. Could
you tell me which band of 12BH7 is sound good?
BTW, Diytfy, could you tell me where are you?
Have fun!
Wilson
Hong Kong DIYER
diy...@my-deja.com
>
> Hi DIYTFY,
>
> I also agree with you on this point. I found 12BH7 was better than
12AU7
> for the buffer application according to the DATA sheet. It is higher
> current, higher heater current, lower output impedance & higher power
> handling. ANd I also found 6BX7 & 6H30 was even better than 12BH7.
Could
> you tell me which band of 12BH7 is sound good?
>
> BTW, Diytfy, could you tell me where are you?
>
> Have fun!
> Wilson
> Hong Kong DIYER
>
> Sent via Deja.com http://www.deja.com/
> Share what you know. Learn what you don't.
>
Hi Wilson,
Even in driver stage, the sound of 12BH7 is 'rich & full' v.s. 12AU7.
In buffer, 12BH7 is better since which has higher 'Cathode to Heater'
voltage tolerance. You know the cathode is up at around 150V when the
triode acting as a buffer.
This explains another disadvantage of SRPP when the upper triode 's
cathode is tired at ~150V cathode to heater voltage. For those are
using SRPP circuit, please try to check the (V) diffenrence between the
Cathode and heater. Good luck!
6BX7 is better than 12BH7 when working as a buffer since it's a power
amp tube characteristic. 12BH7 is better than 6BX7 when working as a
driver since it's higher Rp. Becareful!
However, I suggest a way to better use a 6BX7 as a buffer; you use
+135V on the plate of 6BX7, -135V on the cathode resister. the 0
voltage directly connect to the grid of 300B..etc. Many IPT transformer
coupler user change to this circuit and found it better in slew rate
and lower phase distortion.
I'm in HKG near 'Tannoy Silver and Alan and King'
Hv diy fun! know the circuities, know the commercial propaganda!
Diftfy
reylon...@my-deja.com
12AU7?Most stereo systems could probably benefit from at least some
amount of taming,but we all dream of having our cake and eating it too.
To wit,could a system sound both full and fast,could big speakers in a
smallish room sound full and retain a pinpointed soundstage,
maybe someone could compile the dreamlist to make us drool with
Pavlovian certainty.Raanan
reylon...@my-deja.com
early in the morning.Wanted to add that when I had the 10B
I couldn't hear that the 12AU7s were noticeably detracting from the
sound(Ithink that there were 3 of them in the circuit)but I kept on
wondering how it would sound with the 6CG7s.Using 12AU7s in the 10B
other than tfk/s did impart an annoying sleepiness.Raanan