Made in Poland by a small local company which preferred to have their
name withheld.
Lampized by Fikus in 19th april 2009
OK, so there is the story. I felt that I need a new amp.
I asked myself some questions about the criteria.
I figured that I want:
Tube amplifier
Two mono blocks because it is nice to have source in the centre
and monos on the sides
I want triode not pentode
I want it to be pure yet simple, powerful but subtle
So there I was - my choice is really limited to four supertriodes: 845,
805, 211 and the Russian copy - GM70.
Of course - I can not afford the Western made amp like that. A SET Mono
costs minimum 10 000 Euro per pair or much more.
In China at the moment only Meixing Mingda offers a mono 805 amp
pair for 1490 USD with 500 USD shipping, plus EU customs and VAT.
So we are talking in the end 2000 Euros. Not bad, but still they
probably require substantial reworking.
By lucky coincident I found an auction for the Polish made "garage
industry" amplifier pair - using the mighty GM70.
The pair sold for 1000 Eu with two separate monstrous power supplies.
I expected something fishy, So cheap for the real amp look-alikes
? But hey, what the hell, if worse comes to worst I will have to RE-DO
the whole amps but EVENTUALLY I will have them singing. So I took the
risk and the plunge. In my imagination - I bought the case and tubes
with sockets, I did not expect HIGH-END for one grand.
GM70 Single Ended Directly Heated Triode mono amplifiers
The black wiener-dog thingies are power transformers for dual 250 and
separately for dual 620 V AC in two boxes for L and R channel,
before these voltages get rectified inside the amps.
I brought them home and admired for a moment - just what I needed - a
Russkij Gakuon for the poor. In my very own living room.
But after first listening - my face looked less and less happy.
They played something, no,
not MUTE. But the music was poor. It was like from a very cheap stock
music angel or worse.
So what I had - was not a complete
melon, but not a gem either.
I started scratching my head and sniffing around.
The amps internally look okay. Hand made - that's for sure, but made
well.
All supplies are separately tube rectified. (including the big GM70)
All supplies have chokes - GOOOOD.
All supplies have CLC topology with good caps.
All supplies have separate transformers.
So far so good. So why such poor sound?
I tested every point and I found that one transformer had mis-wired
secondary and produced only 1/4 of voltage for GM70 Anode.
BINGO. This amp circulated around Poland like a hot potato and nobody
seemed to like it. Nobody was able to fix it either. Hence the price.
After assembling it again - ooooo - much better. Now it plays like a
nice stereo kit. Sound is even, stable, image focused - all is OK.
BUT
I expected a sonic blowjob, not mere Okay sound. I had to do better.
This amp was still missing somehing compared to the Music Angel 845
with Dietmar
front end.
But potentially it should be mopping the floor with the Angel because
of the whole construction being so much superior.
I spent many weekends experimenting - with different options of the
input and driver.
Now is the tricky part:
1. There is ONLY ONE tube at the front end. Normally - there should be
at least two.
2. This tube is 6H6P which has small amplification ratio.
3. GM70 likes strong drivers, maybe a DHT like 300B or something.
4. Dietmar schematics to the rescue ! But - it is calling for 4
triodes, I have 2 in one tube. No good, no good.
A possible way out is adding one more tube (2 triodes) and that would
do. I could for example add a 6H2P for input amplification and the 6H6P
would become a powerful driver.
But that requires drilling one hole for the socket and getting a
"parasitic" power supply and heaters.
So I desperately tried to keep it at one tube and finally I arrived at
the scheme that works.
It is not Gaku-On but it plays like my best Angels and Liungs used to
play. It plays VERY VERY well. And the amp is so simple, so pure,
without interstage transformers, complicated circuits - nothing like
that.
On good lampized CD the music really makes me shiver in excitement the
way a SET DHT should.
The tube circuit for CD lampizator is a very easy job, because the
triode - capable of 200 V signal swing - is swinging only 2 V so it is
loaded at 1% of its capability so to speak.
In this amp - the operating point must be DEAD SPOT-ON. And each
and every parameter is utilized to the maximum - voltage, current,
power, heat and so on.
For the lampizator - this tube can work at 50 V, 100, 150, 200 or 250.
It can draw 2 mA or 20, does not matter. But in the amp - every ohm
matters etc. This one tube must provide a circa 50 X amplification and
do it with very low output impedance. Any smallest error and
goodbye good sound. The GM70 will distort like hell.
Anyway - below is the schematics.
ERRATA: There is an obvious error in my drawing - the GM70 triode is DC
heated at 20 V. Not AC.
The +820V DC supply has one more 100uF capacitor by 1200 V DC after the
rectifier and before the choke.
In red area - the section invented by me. Changed from the original
which I did not like too much. It sounded far less like SET. Now
it
sounds already equal to Liung in Dietmar's version, or
Music
Angel. Quite mature, maybe even more refined sound. It can be
attributed to tube
rectifiers in power supply of both tubes and to better output
transformers, or both factors combined.
This setup I came up with for the input/driver is simple, cheap, easy
to build, works stable, not too hot, the 6n6P does not get abused, and
sounds very very good. I will keep this solution. There is no noise, no
hum, no pop, no click. But there is BASS, soo goood, mmm. The
voices are like ghosts. The space is a huuge 3D thing. Oh man, triodes
are the way to go.
I like the fact that I was able to keep one tube only in input section,
there is no need for interstage transformer, no need to use 300B as a
driver, but to keep the signal high enough I had to use in the first
triode the cathode resistor 1K with bypass electrolyte (Oscon
SEPC series 470uF/25V), and no need to use
exotic tubes.
My beloved good old 6n6P is just a great versatile tube.
Besides - I did not have to mix russian GM-70 with non-russian tubes,
making this amp less kosher. This way it is a true monument of Russkaja
Tiechnika at its best. And it is deployed for the MUSIC and not for the
nukes ! Thank God the guards of the Russian National Defense warehouses
and stock depos are easy to bribe with vodka to remove some
"unnecessary" parts from their war machine.
The reason why I did not try to play GM70 in class A2 with 1200 VDC
power supply and high grid current was the necessity to build triple
series caps for anode to reach 1300 V ratings and order custom chokes
and build a special DHT driver section.
My GM70 is great as starting kit for the DHT supertriode territory
exploration.
So far - the GM70 NOS tubes come cheap and plenty so I built up myself
a stock for the future. Mr. Putin will not threaten me with an embargo.
I have supply for 20 years !
After one year I confirm everything that I wrote. GM70 is a great
triode - cheap, stable, nothing goes wrong with it. I installed a 24
position attenuator in the front plate and I have nice adjusted volume
monos.
NOTHING is broken during the first year, except that all screws are
loose (everything was open too many times).
Copper plate version of GM-70
Recently I bought the COPPER plate triodes. about 5 x the price of
graphite ones. (USD 200 a pair, new and mint, made in 1982. The year of
"almost nearly" Soviet intervention in Poland)
The first thing that stroke me was (no, not a 900 V shock) the
light. These triodes probably emit the brightest filiament light of all
tubes in the world. Like 40 watt bulbs, but much warmer, reddish from
the copper plate refflection. Looking into this light is magical, like
into a fireplace.
The sound is good, maybe 10 % better in mids, equal in highs, and 50 %
weaker in the bass.
It may be my amp operating points being not optimal for this tube, but
"internet people" agree - weaker bass and better mids. This is closer
to 300B sound. For me - overall net change is negative. I absolutely
love the graphite GM70. So I can have a spare pair of copper for the
hell of it, but for every day operation I am gonna stick with the
graphite.
Maybe on lesser speakers - like minimonitors - the bass issue would not
matter, but mids would be better enough with copper. But on my no
compromise Tesla bass setup - I miss the THUNDER.
Three and a half years later - GM70 Filus Lampizator amp is born.
Three and a half years later -
first of all, the wooden Polish amps served me flawlessly all the years
and I never had to change a single tube.
After setting up my business as a DAC manufacturer, I used the amps to
evaluate my DACS prior to sending. But I also felt that my DAC
customers are struggling with their amps. Either too weak (300B) or too
brutal (Push Pull KT88) or simply - transistor (not musical
sound). I saw the opportunity to offer a good amp to those
customers.
So far, I havent seen any serious competition to "big triode" amps -
and only GM70, 845, 805, 211 and 813 tubes make me interested at all.
I had the following design criteria: Triode mode on all stages, Zero
feedback global or local, zero silicon in the amplification
circuit, no signal cable inside, no sound altering tricks
anywhere, no interstage transformers, no PCB,
Since I have a reputation as a Soviet technology advocate - I decided
to skip the Chinese Suguang imitations of 845 and 211 and settle on the
real deal NOS GM70 triode. Especially that it is: A) cheaper and B)
much more powerful than the 845. The supplies of the NOC triodes should
last our lifetime.
I chose monoblock approach to reduce overall unit weight to be more
manageable
I chose tube rectification for all stages.
I chose one box approach over the separate supply box for simplicity
and short distance from power source to the consumer.
The design is a result of my DAC experience - the first two tubes -
input and driver - are configured and powered just like in the
Lampizator Level4.
I designed the main box to be large enough so I never have to take
space-related compromises. EVERYTHING I need - will fit in.
I designed the top plate that holds everything. The amp can be operated
without the box - the top plate holds all transformers (4 of them) and
all parts and tube sockets and RCA sockets and speaker terminals -
EVERYTHING on one thick aluminum plate.
The choice of the box is optional - as wooden, metal or black neutral.
The choice of anode voltage is a practical 1000 V, not over 1KV,
to be able to build 1000 V supplies. Going over 1000 V requires very
hard gymnastics and redesigning everything and probably more space and
weight that we can imagine in anyone's living room.
The small tubes must be powered with around half of the main anode
voltage, meaning - 450 V DC
The driver tube must be as current-capable as possible. Hence the
choice of 6N6P doubled which can swing 300 V peak to peak at 30 mA
current.
The input tube must be linear and pure. The QUALITY is of paramount
importance here.
Summing up: I built the Lampizator analog stage for the small tube
section, with EI power transformer, toroidal powered AC heaters, choke
loaded tube rectifier, CRC separate sections for every tube anode
(three in total).
The big power section is a single ended pure class A zero feedback
design with 1000 VDC anode supply, CLC power filter, 0,3 mm steel
output transformer (laminated, annealed, multi section).
The bias is manual (with negative supplies and a pot for adjustment and
the needle meter for verification). The choice of excellent Ogonowski
Output Transformer was preceeded by othert transformer testing and the
Ogonowski was a winner by a good margin. No, it doesnt have silver
wiring but otherwise it is there with the best.
There are no resistor in cathode section.
The power tube heaters are Soviet designed DC scheme from dual power
windings of +/- 20 V.
Each power tube is precisely matched and manually de-hummed.
One of the design criteria was ZERO SIGNAL CABLE INSIDE. Meaning -
there is ONLY your own precious cable between source and amplifier's
input tube. I don't run 2 feet of no name cable inside to drive the
signal from behind of the amp to the front. Whatever is your choice of
interconnect - it wil be the only one we will have in the chain. Thats
why the RCA socket is so close to the front where the input tube has
it's grid. The pot (stepped attenuator) is the only part between RCA
and tube grid. As a necesstity we use 2 inches of solid core silver
wire from RCA to the pot but no more than that. So if your favorite
flavor of cable is say Van den Hul Carbon - we will not contaminate the
system sound by adding 2 feet of mickey mopuse cable. Or even a good
Siltech for that matter. Only your cable will play.
GM-70 Monoblock pictures
Above: the silver front version of amps with the Lampizator DAC in the
middle
Above: the Lampizator mono amp (left) compared to Mr. Liang stereo
integrated from China (based on 845).
Time flies, it is 2013 now. It 's been 4 years since I devoted myself
to the audio business, no longer a hobby. Looking back - here is what I
think about the article written above:
