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Tubelab Discussion and support of Tubelab products, prototypes and experiments

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Old 10th December 2018, 03:31 PM   #1
Tubelab_com is offline Tubelab_com  United States
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Default After a 14 year run, the TSE must DIE!

Friends, the time is here. After 14 years virtually unchanged, the TSE as we know it must go away. Why?

In today's electronics market a semiconductor company introduces a new part, makes a test batch, prints up a data sheet, and announces the part. If it doesn't generate some immediate interest, it may die right there with no production parts ever being made.

If there are enough inquiries via the sales engineering force a production batch may get made. Sadly if the new part doesn't find it's way into a million unit volume product, or have a high enough profit margin to support a lower volume within a year or two, it will vanish from the market.

We (Motorola) spent a lot of time redesigning phones as parts would come and go. It was a big issue in products with a long life like police radios. Today's high volume consumer electronics have a two year or less product life. New phones come out in less than a year. With each new phone, new semiconductors arrive, and old ones die off. So what does this have to do with the TSE?

As we have seen with the mosfets, the old Toshiba 2SK2700 went away long ago, a victim of slow sales and ROHS, but newer and better mosfets have always appeared that drop in place. They tend to stay around for a year or two, then vanish.

Unfortunately, the Sharp filament regulator chip went extinct several years ago. It was a new part 15 years ago when the TSE was designed, and remained available for over 12 years, but went away when Sharp had financial difficulties. Sharp is now owned by Foxconn and is no longer a force in the semiconductor market.

It seems that the TSE builders were the only people using these parts, Mouser and Digikey both had ample stock, so things were still OK, and I quietly began looking for a suitable replacement part. There is NO DROP IN REPLACEMENT PART available.

I have tested some of the regulators that have similar specs, and so far find none that work as good as the old Sharp regulator.

Recently, almost overnight the regulators in stock at Mouser and Digikey vanished. I noticed that a third party reseller started selling these chips at about the same time. Did he simply buy them all and triple the price, or did the major distributors flush their inventory of slow moving parts, I don't know. The chips can be found here, I have never ordered from these guys, so I don't know what they really have or how they got them:

PQ5EV5

I have ZERO boards left in stock, and I have been including a Sharp regulator free of charge with each board purchase, and will continue to do so until these boards are gone.

My chips are from a Digikey purchase made in 2013 when I was preparing to offer parts kits for the TSE, SSE and SPP. Family and job issues killed the parts kits plans.

Once these boards are gone, I will likely not get any new boards. A redesign of the TSE is in the cards, but what do YOU want to see?

Some possibilities are:

1) a re-spin of the same design with a different regulator in place of the Sharp chip. This would use the same size board, footprint, and same chassis design.

2) a two board approach with the power supply moved off board to allow for more room on the amplifier board. The TSE was originally intended for 45's and some modern 300B tubes are nearly touching each other. Heat is another issue with the current design at high supply voltages.

This would be a clean slate design, be a different mechanical design and need a new chassis design. It could incorporate the same screw terminals that are seen in the SSE and SPP boards. Other circuit improvements could be incorporated, but the amplifier design is sound, and I see no major changes. The power supply could be improved, but is constrained by size in the current design. Two boards would obviously cost more than one board, but the board cost is not a major issue in a high end amp. The separate power supply board could lead to multiple supply choices for different build choices.

3) a larger one board approach with power supply and amp on a single board. Again, a clean slate design, but with more design restrictions than a two board approach. This may still be limited in size to fit the standard post office mailing supplies.

4) mono blocks. Again, and idea to minimize heat.

5) I'm open to suggestions.......what are YOUR ideas?


PS......there ARE some new amp designs on horizon, both P-P and SE....and then there is the UN-SET (currently still a proto)........stay tuned.
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Last edited by Tubelab_com; 27th February 2019 at 02:12 AM.
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Old 10th December 2018, 03:46 PM   #2
mctavish is offline mctavish  Austria
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I have honestly hacked up a few boards to simply use the driver system... Output tubes off-board and a different filament supply (coleman).

I would say Modular would be the way to go. For us diyers paying a bit more for flexability never seemed to be a problem. After all, it was never really a beginners project IMHO.

Regardless George, I am sure what ever you come up with will be great!
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Old 10th December 2018, 05:29 PM   #3
zman01 is offline zman01  Bangladesh
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After a 14 year run, the TSE must DIE!
George,

I also support the idea of going modular. My thoughts are:

1) Keep Power supply board PCB, and make it configurable for single channel or dual channel support (keeping in mind mono blocks)

2) Make the boards single channel, so 2 boards will be needed for a stereo build. Also, I am assuming that the single channel PCBs will be smaller. If folks want to, they can go for mono blocks too by combining 1 single channel PCB + 1 power supply PCB

Smaller PCBs should be lower cost individually, and for a 45, 300B, or 2A3 project, a few $$ more for 3 x PCBs (assuming a 2 channel build) should be acceptable to the community.

Too bad you have to retire the design because of parts becoming EOL. However we expect that you shall be able to come up with an even better design if you put your mind to it, and time allows.

Wishing you all the best George, and look forward to seeing what other diyA members have to say about a new TSE. (Should we start calling it TMSE - Tubelab Modular SE? )
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Old 10th December 2018, 05:40 PM   #4
mctavish is offline mctavish  Austria
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It should be called the BORG project!! An unstoppable fleet of square boards that together make an unstoppable amp! Driver boards, power supply boards, combined to assimilate all they encounter in to the vacuum tube collective!!!

But seriously... I feel like a stand -alone power supply board would be very attractive to many, even as it stands on its own. Then a driver board with the power tubes off-board. Even the greenest newbies should be able to run 8 wires to a tube socket mounted on the chassis. I would like to reiterate, I would have no problem paying a bit more for flexibilty and I feel others would be ok with it too. Lets face it, the costs of transformers for a quality tube amp far outshadow the costs of a few pcb boards.....


Those wanting to build a quality amp should not skimp on the transformers, much less a few more $$ for quality boards produced by a compentent designer with decades of tube experience.... My 2 sense...
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Old 10th December 2018, 05:42 PM   #5
zman01 is offline zman01  Bangladesh
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After a 14 year run, the TSE must DIE!
Good points mctavish.
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Old 10th December 2018, 08:17 PM   #6
w5jag is offline w5jag  United States
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If redesign ...

Pads sized / spaced for screw terminals for the connections into / out of the board - the builder is free to use the terminals, or solder direct to the pads as he / she sees fit.

Pads for local plate to grid negative feedback.

Current metering off the cathode, rather than the anode.

Pads for tip jacks or similar probe receptacles at test points to make metering easier for folks that don't install permanent meters. These could also be used to hard wire in meters.

Maybe some type of buck / boost switcher supply for the filaments instead of a linear design around a regulator chip. I was really impressed with how easy it was to dial up a voltage and current with the cheap Tusotek dc-dc buck / boost converter modules for fooling with oddball tubes. That would also eliminate / ease some of the heat issues around the filament regulator. Audiophiles might not like that type of supply, but they don't seem to like DC on the filaments at all as far as I can tell ... I would think switch noise on the output, if any, could be taken out with a notch filter. Or put both types on the board, let folks choose which one to build out ...

edit: why not make the high voltage a buck / boost switcher also? One transformer for all variations of the amp. State of the art.

I don't have an opinion on whether or not the power supply needs to be off the main board. I would think only the filament supply needs its own board if you go that route.

Crazy idea - option for different power tube sockets ... octal for things like 6A3, and for using indirectly heated tubes like 6550, 6L6, etc. I'm not sure there is a universal mount for tube sockets, so you might need something like a hole in the board, where a smaller daughter pcb with the correct socket installed can be screwed down onto the main board. Pads on each board to solder up the connections. The anode pad needs a through hole or socket for a plate cap lead. That would also let folks use 46, 47, 807, etc. Elekit had something like this on one of their amps where the user could switch between 6AQ5 or 6V6.

If you allow for indirectly heated tubes why not a regulator for a screen supply? I have some three terminal high voltage regulators

https://www.mouser.com/ProductDetail/689-LR8N3-G

that I have been meaning to try in a screen supply for my SSE, but that other project has been taking all my free time ...

Win W5JAG

Last edited by w5jag; 10th December 2018 at 08:46 PM.
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Old 11th December 2018, 02:14 AM   #7
Tubelab_com is offline Tubelab_com  United States
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Quote:
Pads sized / spaced for screw
That is pretty much a given for everything I have designed since the TSE. As I stated many years ago the TSE was never intended to be a kit, or construction project amp design. I made one (complete amp)....I sold it... repeat. After a while I couldn't make them fast enough, and most of my customers were technical people, so I got some boards made and wrote up some basic assembly instructions. The instructions were improved several times, and loaded onto a CD, then someone said why don't you put this on the web..........

In all that time, the board hasn't changed. I still have one of the original home cooked PC boards from those early amp builds. It still works too.

Quote:
Current metering off the cathode, rather than the anode.
That would require two completely independent floating power supplies, one for each tube. Doable, but complicated.
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Old 11th December 2018, 02:22 AM   #8
kevinkr is offline kevinkr  United States
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After a 14 year run, the TSE must DIE!
Coleman regs are sold in pairs and would complement a redesigned TSE quite nicely. I stopped making my own and starting using these instead some years ago in my own amps. (The only thing I use in my stuff that is not my own design.)
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Old 11th December 2018, 07:37 AM   #9
OldHector is offline OldHector
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I recently bought a TSE board, and have been struggling to source some of the obsolete parts, though there are helpful sites listing equivalents.
Could you consider mailing me a regulator chip? I have fixed the resistors, and have PCB 300B sockets on the way from China, and also some quite exotic Lundahl OPTs, so am already quite committted to this project.
BTW, have just wired together my SPP, which was my first foray into this dream to build my own amp, and initial impressions were fantastic. My partner listened in awe to what she thought was a poorly produced Elton John album, and couldn’t believe the sound stage. So now it is not just a pointless hobby ;-)
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Old 11th December 2018, 02:48 PM   #10
Evenharmonics is offline Evenharmonics  United States
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Another vote for modular system.

Modular monoblock is even better.
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