Dynaco / TDF ST-70
 

 

Story: Customer 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
 

 

Story: Customer brings a pair of mono amps over and want a over haul.

Diagnoses: 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 of amps.

 

   
  Wright 2A3 Mono Blocks
 

 

Story: Customer 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 transformers!

 

 

   
  Jadis Orchestra Integrated Amp / Preamp
 

 

Story: Jadis(s)

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!

 

 

 

   
  Pioneer SX737
 

 

Story: Customer brought this in for an up to spec service.

Diagnosis:  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.
4/ Provided 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.
6/ Channel 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 $170-180)

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.

Diagnosis:  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.

 
   

  Wavelength 300B Tube Amp
   
 
Story: Customer brought this in due to hum and crackling noise. At first left and both channels shortly after.

Diagnosis:  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.

Diagnosis:  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

Diagnosis:  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!

 
   

 

  Quicksilver PowerAmp
 
Story: Customer seeking for heath Inspection, bench test and possible upgrades on the budget.

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.

Diagnosis: Before 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.

 
   

 

  Cary SLP-98 Tube Preamp
 
Story: Another humming SLP-98, customer also looking for full upgrades.

Diagnosis: First 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. 

 
   

Before:

After:

 

  McIntosh MC-2505
 
Story: Customer requesting bring up to spec and find the cause of hum.

Diagnosis: Some 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 amps
 
Story: Hum, burning tubes, all sort of weird things you can think of. This is the X number of these budget 845/211 amps we encountered. Like many 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.

Diagnosis: No 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 boxes.

 
   

 

 

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 concern.

 

   

NEXT PAGE

(portfolio continue)

These are the most cases we have encounter recently, not including any of the commercial/confidential works.

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,

Thanks for supporting us!

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

   

 

   
         

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