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Tubelab Discussion and support of Tubelab products, prototypes and experiments

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Old 29th January 2012, 04:03 PM   #511
brucetassin is offline brucetassin  United States
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George, whats your eBay seller ID?
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Old 30th January 2012, 12:18 AM   #512
Tubelab_com is online now Tubelab_com  United States
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My Ebay ID is tubelab*com. They wouldn't allow a dot in the user name even though there are other users with their user name the same as their web address.

I didn't make it over to the warehouse today, so I probably won't start listing stuff until next weekend. I have already received a couple of PM's requesting a particular tube.

I got a collection of about 100,000 tubes given to me for free in exchange for a couple of weekends of work moving it all. Apparently a collector of WWII and Korean War military electronics had died and therefore wasn't paying his rent. The warehouse owner had a salvage operator haul it all away as metal scrap. A friend managed to intercept two semi trailers full before it went to the scrapper. I helped sort it and load it all into his warehouse in exchange for all the tubes and other parts. All of the tubes were pulled out of military spare equipment so none of it was NIB, but some were obviously brand new, just installed into the spares. Some were old and crusty looking, but all should have been good......before the scrappers came. All of the bins of tubes that had been carefully sorted were just dumped into boxes and 55 gallon drums. About a third were broken, and some others had severely corroded pins. All of those have been discarded. I must have thrown out about 1000 broken 807's and 1625's.

Since then I have sorted most of them and have been selling, giving away, and even tossing out some of the stuff that I will never use and no one else seems to want. I would guess that there is still 10,000 loose tubes in the warehouse. No, none of them are rare audio tubes, most are common military surplus from the 1950's. Lots of other stuff too.

I have worked at the same electronics company for 39 years. They have been downsizing and spinning off divisions steadilly for the last 10 years. It is only a matter of time before my number comes up. When it does I will move to a place where the cost of living is much less, and all of the "stuff" isn't going with me.
Tubelab, it's 5 year mission. To explore strange new tubes, to seek out new circuits and topologies, to boldly go where no tube has gone before......
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Old 30th January 2012, 01:40 AM   #513
Cassiel is offline Cassiel  Libya
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Originally Posted by tubelab.com View Post
I was out all day. About 5 years ago "the USA's largest Ikea store" opened about 3 miles from my house. I took my wife there today for the first time. It took 4 hours and cost $636! Tomorrow I get to build all the stuff.

Hi George, I was at Ikea the other day and I bought something that could be used as a tube cage. I'm not sure I will use it yet. It's dirt cheap anyway. Maybe somebody finds this interesting.
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Last edited by Cassiel; 30th January 2012 at 01:43 AM.
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Old 30th January 2012, 09:53 AM   #514
Ian444 is offline Ian444  Australia
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John L,

If I built a 2nd SPP I would go with a standard power tranny instead of the Antec, for better looks, and to save hand-winding the heater winding/s. Been that long I can't remember exactly which winding I had to wind. Also that tranny runs pretty hot, but within spec, and isn't much or any smaller than a standard EI tranny.

The use of JJ EL84's is because they handle the higher voltage and work well, and at reasonable cost, and easy to get. Your NOS tubes should work and sound fine, but who really knows until you plug them in.

For output trannies, I would go for Edcor or Z-565 since I've heard a lot of good things about them. The choice of output trannies is not going to make or break the amp as long as you go for reasonably good quality, and I believe those trannies fulfil that requirement easily.

Regarding copper sheet for the top of the amp, would a large blank PCB mounted on top of the top plate be worth thinking about?

I suggest buying a cheap temp-controlled 40W or 50W iron with a 3mm or 5mm chisel or screwdriver tip to build the SPP PCB (if you don't already have one). Some of the ground connections require a heat reserve that smaller irons or tips will have difficulty supplying, leading towards lower quality solder joints, dull and grey instead of shiny.

There's been an area where a problem has occurred with some builders, that is that the B+ can be too high for the tubes, usually solved with the JJ EL84 tubes. If you choose a power tranny with a lower secondary voltage, then you can run any EL84 tubes you like, at the cost of slightly less power. If you have 2 power trannies to choose between, one higher voltage, one slightly lower voltage, I would choose the lower. It is difficult to predict what the final voltage across the tubes will be on any given day, maybe some of the USA builders could give some advice here.

Anyway, good luck, the SPP build is one I am always glad I did, for I still like it very much. The hardest part is choosing the trannies, after that, it should be smooth sailing.
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Old 30th January 2012, 08:23 PM   #515
John L is offline John L  United States
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Ok, here is what I believe I need:

PT: Edcor XPWR008-120

OT:Edcor CXPP25-8-7.6K

Or should I just get a 15W OT, which is a little cheaper?

I've also seen this CXPP25-MS-8K/23%. Is this a better substitute?

If anyone can come up with a more appropriate Edcor, please let me know, ok? After all, there are so many of them to choose from.
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Old 30th January 2012, 09:46 PM   #516
rmyauck is offline rmyauck  Canada
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Thumbs up for 23% UL OPT for reasons mentioned . Optimal for EL84/6V6 so if they offer it ,probably good to take. Can't hurt & 8K will give lower distortion too.

The 15W one will have lower poor bass and more dist. in highs. I have tried small trans compared to big ones in my vintage EL84 PP amps and you really notice the difference. Sounds more you are there at a live performance.

EDCOR Electronics Corporation. CXPP25-MS-8K/23%

PS . This one as it is a bit easier on tubes and you can lower R! Just a thought as DCR of PS being lower may be a good thing? Read good things about that, and actually maybe why George liked the 6CW5 a bit better as 39 ohm used in that version is a fair bit lower.

The other transformer mentioned was the 275-0-275 and this one gives a compromise between the two.

EDCOR Electronics Corporation. XPWR081-120

Yours linked also has lower Amps for 6.3 & 5V taps than the above one.



Last edited by rmyauck; 30th January 2012 at 10:16 PM.
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Old 30th January 2012, 10:43 PM   #517
rknize is online now rknize  United States
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I'll second Randy's suggestion that you go with the 25W transformers. The OPT is one of the best places to spend your money and one of the more difficult things to swap later. So if it is within your budget, you should spring for them.

The Edcor XPWR008-120 is an adequate choice for this amp. Edcor is generally more accurate with the designs than Hammond, so you should get a slightly lower B+ than what George recommends. This will make things easier on the screens of the output tubes, some of with don't like the high B+ of the suggested design. The XPWR081-120 is lower still, but has a lot of heater winding capacity that you don't need. It's a little more expensive and is physically larger than both the 008 and the OPTs.
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Old 30th January 2012, 11:38 PM   #518
rmyauck is offline rmyauck  Canada
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On that XPWR081-120 I just looked at the WT. I was also used to having vintage integrated with huge PS trans. I thought additional fil. wouldn't hurt and may run cooler.

I guess you wanted to add some kind of preamp the higher fil. V. could be handy for some builds.

I got looking through the now amazing list Edcor has which is sure growing so I thought that one might be worth a look.

Speaking about OPT size I wonder about using the approx $70 Edcor 50W 8K in this or similar application for more bandwidth? I noticed the bandwidth for vintage gear at 1W is very wide. I think this would work good as Douglas Picard an Eng. from MI who has posted here and AA and AK and possibly other sites liked the Hammond PP 1650R 100W 5K OPT's used at about 40W for a great bandwidth and sonics. They can be had for only $105 each.



Last edited by rmyauck; 30th January 2012 at 11:48 PM.
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Old 31st January 2012, 02:03 AM   #519
rknize is online now rknize  United States
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Indeed, it would run cooler. The lighter load on the primary would also make the B+ come in a little higher than expected. This would be fine since it is spec'ed at a lower voltage anyway.

As far as bigger OPTs, I think it is possible to have too much of a good thing. The larger 25W cores on my SSE probably take some part in why that amp is less detailed than my TSE. However this amp is PP, whose OPTs are inherently smaller to begin with. It's probably less of an issue. The 25W SE OPTs on the SSE are heavier than the 60W OPTs on a PP amp that I have.
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Old 31st January 2012, 02:24 AM   #520
rmyauck is offline rmyauck  Canada
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So on PS trans it would probably be better to spend on higher mA rating as George mentioned would be a + on his site.

I found a thread in AK with a guy who builds DHT SE with low Watt tubes (Under 10W) & swears by the 28 lb Hammond 1642 SE 5K 75W rated OPT. Pretty pricey to try , but you probably get what you pay for.

Hammond Mfg. - "Classic" Single Ended Tube Output Transformers - (1627 - 1642 Series)


Last edited by rmyauck; 31st January 2012 at 02:28 AM.
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