||Dynaco / TDF ST-70
looking for our version of TDF ST-70 update.
This is our version for the ST-70 which uses ECF80 / 6BL8 / 6U8 / 6GH8 and ECF82
...etc like tubes, instead of the lifeless 7199, and the
main reason making ours.
Fully loaded of the new board
are $299 cad including M-caps and metal film resistor. The
board is drawn by ourselves at OEM par like how we
drawn for our industry clients. Available extra for DC
Balancer control for the EL34 output tubes to maximize
durability and performance.
42 Watts output with even
better distortion figures.
MORE: Convert to Super Dynaco is available,
or you simpily want a new nice looking chassis to convert
over, or you have some transformers kicking around wanted to
use. We can ran this amp with tubes like 6V6, 5881, 6L6,
KT66, 7591...etc too.
For even better design, ask
for our TDF ST-X version, which is available for $50-
more, it uses 3 X 6922. It has nothing to do with the
original ST-70, but It will more likely to give your Marantz 8B a go.
We like our ST-X more.
||Eico Mono Blocks
brings a pair of mono amps over and want a over haul.
After inspection, we notice they are non matched and made
from different hands and time. But it doesn't matter as all
the parts looked bad enough we will strip everything out and
reconstruct everything, with new quality parts and new
Mundorf Supreme Caps.
Solution: Since we do
it all, we also by passed all the useless features and
plugs. Reinstall new IEC powercord socket, new RCA inputs,
new speaker output terminals ... etc. Making it a pair of
pure mono blocks power amps. We also did an alignment to
make sure both amp are close enough in power outputs. A
healthy rock solid 25 WPCS and a really great sounding pair
||Wright 2A3 Mono Blocks
reports of premature clipping/distorting at louder passage
and when turning up volume, as well to cure hum noise and
seek for upgrades.
Diagnoses: After we
looked at the amps, we see good potential on these as it
comes with quality irons, Hammond (Canada) Power transformer
and the 2A3 Filament Transformer and an over sized 10H input
choke transformer. The Output transformers are also a
Magnaquest of USA. After checking on the RCA 2A3 tubes and
USA 6SN7s and 5Y3s (although one side tested weaker, we
recommend our customers always get matched pair of rectifier
tubes too, you see, for example here, one side is tested
5.3w and one side is shy of 5w at nominal) with no problems,
then we start looking at its simple circuitry (which
measured poorly at 2.8W only). And we are happy to see there
are many ways in improve and bring out the full potential on
these amps, and keep it no negative feedbacks applied.
Solution: Anyway, to
keep it good on both output quality and cost. We offer in
changing the driver to a SRPP design, improve the power
supply and groundings, as well replace all the entry level
and failing passive parts with new beefed up ones. After the
operation, the amps is far more quiet, and measured
exceeding originals specifications with a clean bill of
health. And all these operations costed our customer $180.
There are far more upgrades
we can do and suggest, such as replacing the 6SN7 with the
6SL7 for more drive and perhaps drop in our designs with
some high end caps and bits. Applying feedbacks to proper
locations correctly can also greatly improve on S/N hum
noise, bandwidth, distortion figures, power/drive, and
sound. We are here to help you to unleash these great
||Jadis Orchestra Integrated Amp /
We don't know
what is done or what happen is to this amp... but if you have Jadis
tube amps and
needs help, we are good at it.
Side: JDP Preamp. It's making
mild hum on to one side, customer brought it in to us which
he explain no one can find out the reason, and we fixed it
in less than 30 minutes. The circuitry has nothing
wrong, but when it ages, there are adjustments required.
Good solid preamp otherwise!
Story: Customer brought
this in for an up to spec service.
After our inspection, we have found quite more than usual
parts need to go. Over 40 bits were needed to go. Here is
what included on this usual up-to-spec service:
General clean-up and
tune-up from AM-FM section to phono amp and all
amplification stages. On the way, replace all
defective light bulbs and all signal coupling
caps that are necessary.
Here is what's
included as well:
1/ Re-grease for all
power transistor and heat-sink.
2/ Tight up all
mechanical parts and screw.
3/ Checks all RCA
signal for good connection.
electrical bench test for "dc offset alignments
within 30mv" for both OCL-amp circuitry.
5/ Distortion checks
for max-power rated output @ 8 ohm and S/N ratio
checks as well.
output balance checks within 1db deviation at 3
point test / minimum, middle and maximum. Tone
control are center "0"db set.
Solution: As always,
we try to use all Japanese parts on these Japanese
machine.The result is very nice now, perhaps many parts are
being replaced, both side is making identical power at 39W
at 1%, which is very good figure and is consider as good or
better than NEW.
As there are quite a lot of
these older Japanese receivers coming in recently for
service. Here are the approximately costs to those who
wanted to give their olde but good gears some refreshment.
Clean up, Bench tested and Light bulbs all included:
Minimum: $20-90 (Average of
$70) ; Medium (like this Pioneer): $140 - $220 (Average of
Example of "Minimum"
base on a Luxman R1070
Console / Organ / Industrial Amps
Story: Customer wanted us
to bring it up to spec and add other features
*READ THIS* if
you come across to these amps frequently.
Many of these amps are not protected by fuse, even it works,
you are putting yourself in danger. Most parts and
components on this type of amps are all dried up, you are
risking yourself anytime if you are unsure if safety feature
have been added to yours (Please bear in mind even all parts
are updated, it doesn't help to increase safety).
Solution: As per
customer request, we have added speaker binding posts, RCA
inputs, On off switches, new power cord / IEC socket, volume
control ... etc which are unusual modern features to be seen
on this type of amps. Like this little Single Ended EL84
type tube amplifier here (Top / Bottom Photo), 95% of its
parts are all defected, we did spent 6 fuse just to test all
bugs to make sure it is in sound and safe condition. Even
the last bit of resistor won't do if we don't swap it out
for a new one.
This type of job will be
expensive, as there are too much work to do and
like this amp, we just have to torn it all off to redo
again. 90%+ parts have to be new too.
Photo on the left: 7189 Push
Pull Amp, similar case with this EL84SE Amp, safety features
are added, new modern type of speaker binding posts are
added, as well a up to spec service job.
Story: Customer brought
this in due to hum and crackling noise. At first left and
both channels shortly after.
After our usual inspection, we found nothing wrong with the
parts nor circuitry. The tubes are also good. With our
experience, we immediately know its the tube sockets. Which
is more a maintenance issue rather than a problem.
Solution: A new set of
nice tube sockets + free inspection and benchtest.
Harman Kardon A250 Epic 6L6 Integrated Amp
Story: Customer brought
this from auction said to be in "good working condition".
and wanted us to bring it up to spec.
After our inspection, we just have to turn our client down
and tell him the truth that 99% of the parts are either at
the end of its life or soon. There are also more than 2
switches and pots that are also damaged and there are no
replacement. With half a dozen more old switches and pots in
the path, the best thing to do is to convert it to a pure
power amp, by passed all those front ends.
Solution: As 99% of
the parts are bad (which is not as bad for us), all we have
to do is strip it all off and rebuild it to the original -
which is far quicker and easier. This is now virtually a new
power amp with the original transformers, which is nicely
designed and allow us to switch it to Autobias making it
less headache with different tubes of 6L6GB&GC/5881. Making
this a good example of 6L6 power amp.
McIntosh MC-225 7591 Power Amp
Story: Up to spec request
The condition is not bad at all.
Solution: Brought it
up to spec and exceeded original factory spec for just $130.
Very charm amp we like. The MC225 is one of the best tube
amp from MC, we like it and to some extend if power is not
your first priority, It is better to its siblings from the
design of the transformers, to the efficiency and linearity
of the output tubes of 7591.I remember one of these driving
the entire movie theatre solo!
Story: Customer seeking
for heath Inspection, bench test and possible upgrades on
Diagnosis: As always, we study the original design
before we start out our own way of changes.
Solution: With our
experience, we know the cause and effect of each changes
thru out the circuitry as well the weakest link. Here, do
not underestimate these little works we perform. The spec
and S/N are greatly improved.
Kenwood / Trio KW-55a Tube Receiver
Story: A nice clean Trio.
Customer report unstable running of tubes, red / hot tubes,
sometimes one channel has no sound or not even lid up, the
amp will not keep bias, keeps tripping the fuse and all sort
of hums and blah.
we start, the customer or the previous tech has already
changed many of its caps and resistors to new ones. Some
configurations also looked to be altered. This is going to
be a tough one as things are not in original state. And Yes.
We spent over 3 days just to analysis the receiver, and
another 3 days doing more than 6 different tests, swapping
parts in and out to spot on all problems. Doing one
thing less just won't help.
Solution: At last, we
can say out we almost had to redo the whole amp. But it
should have years of maintenance free of ownership.
Story: Another humming
SLP-98, customer also looking for full upgrades.
thing we do is to pin down the cause of humming, also
putting things back in original design state. The preamp was
looked by another tech, whom did some test/changes on the
circuitry - but fail to put it back to the original way,
even it didn't help fixed the problem. This just
doesn't help because it will stress out something else, soon
or later. At last we were glad we found the problem.
Solution: For the
upgrade. The owner love the original sound so much not
allowing us to change any of its design. Its okay, all we do
is spend more effort on the power supply, as well redesign
the grounding routes to yield the best S/N spec. We also
installed the best caps possible to the key spots. At last,
we are happy to see another satisfying customer.
requesting bring up to spec and find the cause of hum.
defect parts found, as well a failed bulb.
Solution: After bench
test, this just perform and looks like new... we send our
driver to meet the owner 300 km away from Toronto for meet
up as we really do not want to risk the shipping part on
such lovely condition Mc.
Import 845 Integrated Amp + short read on poorly built tube
Story: Hum, burning
tubes, all sort of weird things you can think of. This is
number of these budget 845/211 amps we encountered. Like
other imports without distributor/dealers. BUYERS AWARE. 99% of them comes
with design flaws. Even it is said to be built on a proven
design, it might just fail on the cheap/weak parts being
used or a faulty designed power transformer made to 110V
only (which causes the rest of the design shifted - all
parameters and mechanical values). But not just these new
import amps. We've
seen and see more and more old established brand names facing that
- effect of cost reduction. What's more - in fact most of
these amps with the "famous" circuitry, often copied wrong,
or missing some part of the design we seen on the real
original design. It could be a incomplete schematic they
read, or something that is designed at the DIY level which
differ from design that is ready for manufacturing. These
amps are made to light up only, period. Quality speaking of?
out of the questions to them. To be fair, expensive amps or
established brand names does not mean to be bug free too
(especially those, the original designer already passed
away, or the firm/name being sold to some body else).
How soon they will fail? It
all depends your luck. It could be day 1 or your third time
switching the amp on, it often start with tizz and hum, or a
fail tube. It could be lucky enough to serve you longer than a year. It
all depends where the spikes explode while running in the
amp, and if that part of the circuitry able to absorb the
excitement. *** Remember many of these parts/components are
no name brand / replicas which has no / poor quality and
does not able to withstand the extra stress test - they
probably won't withstand the rated limits. There is
not a 100% cure for these amps, because some where else
might burst the next day. These lower price tag import amps surely
worth the name of garage queen - too much to fix, and too
waste to dump off.
Another thing we want our
audiophile friends to learn. DO NOT BUY 110V amp /
equipments. It is just
not running a bit hotter compare to real North American spec
115V-130V products! It does not work like how you might
think. Its not just a few percentage of a difference. It is
actually stressing the product a lot more. It approximately
putting 15%-20% extra load to the design, which is far more than designed
- no safe guard to be talking of and over the safety limits.
Again *** Remember many of these amps come with parts/components
that are no
name brands / replicas which has no / poor quality in
speaking of. It
depends where it fails at whichever stages on the circuitry,
it could causes safety hazard which we concern most,
especially these large triode SE amps, we are talking about
close to or over 1000V (and god bless these transformers are
really tested properly to the minimal safety standard). There is a reason why good 211/845
cost alot of money! Imagine a pair of good/competent output
transformers (made by real audio transformer manufactures,
not general transformer companies!) are easily north of $600 and
over $1000 easy with the better ones.
need further diagnosis. If you have similar amp and having
problem. It is require another over rebuilt/redesign. Which
you better off buying a new amp or buy our 845/211- we
can reuse some transformers and the tubes. Here, we actually
fitted our own 845 design into the amp, with our
professional skill on making PCBs, It fits perfectly with all
mountings and tube sockets.
Those who really want one of
these large DHT tube amp, good and affordable. Please
contact us. Our version of either 845 or 211 will be one of
the best out there world wide. We are expert in these tubes
as well triode
tubes - we know where our design stands. With Hammond grades
transformer, you are high up enough. It all depends the
quality of the transformers you want to spend at last.
Solution: We've seen
design flaws on product from different countries around the
world regardless big names or not (there are always some
small but quality labels out there to be fair). Solution is to stay away from product like this
without a distributor/dealer. The best thing to do is to consult
with your dealer. If you cannot afford new, ask your dealer
to seek for a quality used/demo ones. Many times they can still give
you warranty on them even it might not be fresh out of
Another similar 6P1 PP Integrated Amp:
(Minimum rebuild cost is north of $200)
Whoever worked on this amp need to be
spank! An oversized 6A fuse is being in place which is an safety
These are the most
cases we have encounter recently, not including any of the
There are much more
works we have done in the last decade included many ugly/unsafe scenarios.
We will try to
update more interesting stories if time permit.
It has been our
pleasure working in the field so far and It is our customer's
satisfaction that driven us,