Oh please some one try a gxse15-8-5k and report back
I'm looking for a first tube project and I've been browsing a bunch of threads about SE amps, like the SimpleSE. I'm really looking for a few hundred $ project, not a $600 project. The killer for me is the cost of iron.
The gxse15-8-5k specs add almost an octave over the XSE for $10 more. I would think that's a killer price point if they work for HiFi
So, can someone (tubelab?) please get a pair of these and plug them into a SimpleSE or similiar amp, take some specs and tell us how they sounds?
http://www.edcorusa.com/products/transformers/gxse/gxse15-8-5k.html
I'm looking for a first tube project and I've been browsing a bunch of threads about SE amps, like the SimpleSE. I'm really looking for a few hundred $ project, not a $600 project. The killer for me is the cost of iron.
The gxse15-8-5k specs add almost an octave over the XSE for $10 more. I would think that's a killer price point if they work for HiFi
So, can someone (tubelab?) please get a pair of these and plug them into a SimpleSE or similiar amp, take some specs and tell us how they sounds?
http://www.edcorusa.com/products/transformers/gxse/gxse15-8-5k.html
The original XSE15-8-5K measured 10Hz to 41KHz (3db) at 1 watt (in a TubelabSE). The transformers are far better than their quoted specs. I imagine that they just spec these a little closer to reality. I will get a pair and test them eventually, but I haven't had the time lately. I am going to test out a pair of the 1700 ohm versions since I have a project that needs this value.
http://www.tubelab.com/BudgetOPT.htm
In reality many of the guitar amp manufacturers of yesterday were concerned with cost, so their transformer designs were just cost reduced to the max. I have my own "HiFi guitar amp" that uses a Hammond HiFi OPT. It also uses a full range HiFi speaker. I love the clear tone, but the metal heads don't like it. It doesn't "Crank" like a Marshall.
These transformers are designed for minimum cost. I have taken them apart. There is NO interleaving, one half primary, all the secondaries, then the other half primary (wound with thicker wire to help equalize the resistances). The laminations are the same thick ones found in their battery charger transformers. BUT, they do sound good if properly derated. The "80 watt" guitar OPT does about 25 or 30 watts with good enough frequency response for HiFi. I an using a pair in my 300B P-P amp!
I just gotta put in a SALUTE 
to George. You contribute a whole lot to the diy community while asking very little or nothing in return. All these transformer tests and other experiments are very valuable to those who can't afford or are unable to test otherwise. (My grad-student budget self included)
Your work has inspired me to build a g2drive sweep amp, something I'm looking very forward to getting together.
thanks again
to George. You contribute a whole lot to the diy community while asking very little or nothing in return. All these transformer tests and other experiments are very valuable to those who can't afford or are unable to test otherwise. (My grad-student budget self included)Your work has inspired me to build a g2drive sweep amp, something I'm looking very forward to getting together.
thanks again tubelab.com said:
I read that page a while back and just reread it. That's a pretty encouraging test on the XSE. One thing I was thinking is maybe doing a SimpleSE with cheap iron and leave room on the chassis in case I ever wanted to upgrade.
Still would need to find a power transformer.
And also a box with a tube cage made out of something I could drill/punch with household tools. I got a kid in the house; anything I ever do with HV has got to be 100% inside metal.
The Tubelab budget is severely curtailed for 2008. The accountant says that Tubelab Inc. must show a profit this year since it hasn't shown a profit yet. Some of those transformers that were used in those tests will wind up in amplifiers that will be sold on Ebay in the next few months.
The power transformer that I recommend is the Allied 6K7VG which is about $42. I have also been able to find useful power transformers in surplus electronic equipment. I saved about 20 old HP audio oscillators from the scrappers truck. The power transformers in these turned out to be just right for a TubelabSE with 300B tubes.
I have seen some pretty unusual amplifiers made out of unusual chassis material. I have seen photos of users SimpleSE's that were made on inverted aluminum baking pans. The PC board and all wiring is underneath the "chassis" however the hot tubes are still accessable.
I built an amplifier using a conventional aluminum chassis, but I found a black steel mesh CD case at Target that made a great tube cage. This allowed the PC board to be mounted above the chassis since it was covered by the cage. The tubes and wiring are underneath the cage.
Well I posted on the Edcor support Forum about whether the GXSE is suitable for hifi and the word is that it's just got more low extension the the XSE but doesn't give up anything.
So, if I get my act together and start collection stuff to build a SimpleSE, I thinka I'll give the GXSE a try. It looks like such a good price point.
So, if I get my act together and start collection stuff to build a SimpleSE, I thinka I'll give the GXSE a try. It looks like such a good price point.
Pukka, I would not hesitate getting the GXSE. After reading this thread, I purchased a pair for a future project. When I built my Simple SE, they were not available, so I went for the XSE.
The problem with both of these transformers is not their performance, but the exposed solder tags for connecting the B+ etc. I have seen these mounted the same as a horizontal mount power transformer, and that is how I would do it in the future. To do this you remove the pressed metal with the mounting tabs. The laminations have holes in them that you can use to pass a bolt through to mount. Cut a square hole in the chassis large enough for the bobbin and solder tags to pass through and mount horizontal with no exposed wires...
Wish I had seen that trick before my build!
Chris
The problem with both of these transformers is not their performance, but the exposed solder tags for connecting the B+ etc. I have seen these mounted the same as a horizontal mount power transformer, and that is how I would do it in the future. To do this you remove the pressed metal with the mounting tabs. The laminations have holes in them that you can use to pass a bolt through to mount. Cut a square hole in the chassis large enough for the bobbin and solder tags to pass through and mount horizontal with no exposed wires...
Wish I had seen that trick before my build!
Chris
Already ordered the GXSE's... after scouting google they seem to be a XSE evolution, XSE's perfected. the only "guitar" in its class is the marketing one, as guitar OPTs are far more sold thant hifi ones.
Funny you mention that way of mounting, is the one I had in mind! hope stray flux doesn't cause problems, but I have seen them inside amps, so that should be a worry.
BTW, any pointers for optimal CCS calculation on the IXYS & driver stage? I'd like to try using 6N1P and 6H30 after the initial as per tubelab's specs build...
Funny you mention that way of mounting, is the one I had in mind! hope stray flux doesn't cause problems, but I have seen them inside amps, so that should be a worry.
BTW, any pointers for optimal CCS calculation on the IXYS & driver stage? I'd like to try using 6N1P and 6H30 after the initial as per tubelab's specs build...
My advice would be to just leave it be with the 12AT7/ECC81 driver, as that is what it was designed to use. The 12A*7 valves have a heater pinout different to the Russian 6*** valves. The clue is in the first number in the valve designator. 12 stands for 12.6 volt heaters, 6 for 6.3 volt heaters. In the 12A*7 valves you can parallel the two heaters to run 6.3 volts by joining pins 4 and 5 together and joining one side of the 6.3 volts to them and the other to pin 9. The Simple SE uses 6.3 volt heater supply in this configuration. In the Russian valves the 6.3 volts will go between pins 4 and 5. To make this work you will have to hack the PC board heater supply. Not sure what your amp building experience is like, but if you screw up the heater wiring layout you can introduce hum. The board, as designed, is dead quiet. I would stick with the specified input valve and experiment with output valves if you want to play around.
The CCS is set up fine for the 12AT7 with the recommended parts. George knows his stuff. If you want to try different valves and different currents, the IXYS data sheet gives the graph for the resistor values to vary the current.
The CCS is set up fine for the 12AT7 with the recommended parts. George knows his stuff. If you want to try different valves and different currents, the IXYS data sheet gives the graph for the resistor values to vary the current.
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