That is great! Glad it is working! I think that like triiode and cathode feedback best, but obviously U/L gives more power.
Bad news is that my amp is not working now
Put the tube rectifier back in, it arced and blew fuse. Took it out, and with just solid state rectifier it blew fuse too. No fuses left. Guess that maybe there was interaction between arcing tube that probably fried the solid state diodes. Will open it up soon and take the board out see if there is something on the board that is shorting out. Then it is a case of waiting a week for my new rectifier tubes to arrive.
The joys of DIY!
Chris
Edit - yes one of the diodes is fried...
Bad news is that my amp is not working now
Put the tube rectifier back in, it arced and blew fuse. Took it out, and with just solid state rectifier it blew fuse too. No fuses left. Guess that maybe there was interaction between arcing tube that probably fried the solid state diodes. Will open it up soon and take the board out see if there is something on the board that is shorting out. Then it is a case of waiting a week for my new rectifier tubes to arrive.
The joys of DIY!
Chris
Edit - yes one of the diodes is fried...
Chris and awhite1159
Can you post the part number of the diodes that you are using. Obviously there is a problem with toasted diodes here, and I would like to track it down. I am using IXYS DSEI12-12A. These are rated for 1200 volts at 11 amps, and I have blown one as mentioned before. The replacement diodes have lived for almost a year without issue, including my 400 volt transformer jumper in place of the choke test. A 1200 volt diode should be able to handle a 425 volt transformer.
Can you post the part number of the diodes that you are using. Obviously there is a problem with toasted diodes here, and I would like to track it down. I am using IXYS DSEI12-12A. These are rated for 1200 volts at 11 amps, and I have blown one as mentioned before. The replacement diodes have lived for almost a year without issue, including my 400 volt transformer jumper in place of the choke test. A 1200 volt diode should be able to handle a 425 volt transformer.
G'Day George,
For the original build I used the exact part specified in your parts list , the 12A 1200v DSEI12-12A. For the replacement I used Philips BY359-1500 10A 1500v fast recovery damper diode.
When the originals failed I had been switching between solid state / tube rectification just before, but the fuse blew when either turning the power back on or turning the standby switch to on from standby (sorry, cannot remember exactly which it was). After I discovered the problem was shorted diodes, I simply removed them and had no further troubles till last night. When the rectifier tube (JJ GZ34) started arcing there were no solid state diodes in the amp. I took the tube out and put the solid state diodes in and it did work, however, twice when I turned it on I heard a short, sharp, mechanical "chirp" noise come from the amp (not the speakers). The amp appeared to work OK. The first time this happened I checked voltage across the external motor run cap and it was about 480 volts DC and about 17mV ripple, the same ripple that I had measured before the tube rectifier went crazy.
After this I tried putting the tube rectifier back in. With the solid state/tube rectification switch still in 'solid state' position turned amp power on - arcing of rectifier tube and one dead solid state diode.
Hope this info is helpful,
Cheers,
Chris
For the original build I used the exact part specified in your parts list , the 12A 1200v DSEI12-12A. For the replacement I used Philips BY359-1500 10A 1500v fast recovery damper diode.
When the originals failed I had been switching between solid state / tube rectification just before, but the fuse blew when either turning the power back on or turning the standby switch to on from standby (sorry, cannot remember exactly which it was). After I discovered the problem was shorted diodes, I simply removed them and had no further troubles till last night. When the rectifier tube (JJ GZ34) started arcing there were no solid state diodes in the amp. I took the tube out and put the solid state diodes in and it did work, however, twice when I turned it on I heard a short, sharp, mechanical "chirp" noise come from the amp (not the speakers). The amp appeared to work OK. The first time this happened I checked voltage across the external motor run cap and it was about 480 volts DC and about 17mV ripple, the same ripple that I had measured before the tube rectifier went crazy.
After this I tried putting the tube rectifier back in. With the solid state/tube rectification switch still in 'solid state' position turned amp power on - arcing of rectifier tube and one dead solid state diode.
Hope this info is helpful,
Cheers,
Chris
George,
I should be more specific about the vibration and when it started. Upon the first power up, which was intended to be a quick fire-up to observe filament glow, I did not have the problem. I waited five minutes and powered up again and that is when the very loud hum started to emanate from the power transformer.
Part number of diode: (My eyes are going. It real small print.) DSEI12 - 12A - IXYS L710
I have the amp playing right now. It sounds great. I have a question about all the different configs. What are the benefits/characteristics of UL vs. Triode, CFB vs. no CFB? Back when I was tinkering with SS and tubes in my HAM days (I was a Novice when I was 16), I built a regenerative receiver and the feedback was to further amplify the signal in the RF section. Does CFB work the opposite and act like a regulator circuit? Or is it the UL that behaves like this?
Playing Metallica 'The call of Katulu' right now.
I should be more specific about the vibration and when it started. Upon the first power up, which was intended to be a quick fire-up to observe filament glow, I did not have the problem. I waited five minutes and powered up again and that is when the very loud hum started to emanate from the power transformer.
Part number of diode: (My eyes are going. It real small print.) DSEI12 - 12A - IXYS L710
I have the amp playing right now. It sounds great. I have a question about all the different configs. What are the benefits/characteristics of UL vs. Triode, CFB vs. no CFB? Back when I was tinkering with SS and tubes in my HAM days (I was a Novice when I was 16), I built a regenerative receiver and the feedback was to further amplify the signal in the RF section. Does CFB work the opposite and act like a regulator circuit? Or is it the UL that behaves like this?
Playing Metallica 'The call of Katulu' right now.
The feedback used in your regenerative receiver was positive feedback. It served to increase the gain, and raise the "Q" of the tuned circuit, which increases the selectivity (narrows the bandwidth). A "superregenerative" receiver actually breaks in and out of oscillation at an ultrasonic rate to improve this effect.
The feedback in the SimpleSE is negative feedback, which has the opposite effect. It lowers the overall gain but also lowers the output impedance of the amp, lowers the total distortion and widens the frequency response. CFB will have a different audible effect on each amp, since it is highly dependent on the impedance VS frequency curves of the speakers being used. CFB can be used in triode, UL, or pentode mode. I find that I tend to use it mainly in UL mode to keep the bass under control on loud rock and techno. I find that triode mode is clean enough without it, and it may remove some subtle details from the music.
Triode mode offers the lowest distortion, the lowest output impedance, but the lowest gain and power output. Because of the low output impedance it is the most tolerant of speakers with a wild impedance curve. A Simple SE will deliver 5 to 7 watts in triode mode.
UL mode is a compromize that is somewhere between triode and pentode mode. Proponents say that it delivers the power of pentode mode, with the distortion of triode mode. It acts like a form of negative feedback since the signal being fed into G2 is out of phase with the drive signal on G1.
In reality UL operation is more dependent on the speaker load, since the output impedance is considerably higher than triode mode. Output power and distortion are higher than triode mode. Your results will depend on how well the amplifier likes the load presented by your speakers. A Simple SE can make 10 to 14 watts in UL mode. CFB may work wonders in this mode on some speakers.
Pentode mode makes the most power, has the highest gain, but also has the highest distortion and output impedance. It is possible to use pentode mode for HiFi applications, but it usually requires both local feedback (like CFB) and global feedback (a loop around the entire amp) to bring the distortion and output impedance down. Pentode mode is highly dependent on the speaker load. It is often used in guitar amps for this reason. This is why the characteristic sound of a certain amp depends on the amplifier circuitry AND the speaker characteristics. I have seen a SimpleSE make 20 watts in pentode mode but it didn't sound good for HiFi. The bass was all muddy and boomy. It absolutely screamed when fed by my guitar preamp.
It would appear that the IXYS DSEI 12-12A parts have a problem in this application. I have used them without issue in my other amplifiers. I will begin the search for another part.
Metallica at 3 AM, your neighbors must love it!
The feedback in the SimpleSE is negative feedback, which has the opposite effect. It lowers the overall gain but also lowers the output impedance of the amp, lowers the total distortion and widens the frequency response. CFB will have a different audible effect on each amp, since it is highly dependent on the impedance VS frequency curves of the speakers being used. CFB can be used in triode, UL, or pentode mode. I find that I tend to use it mainly in UL mode to keep the bass under control on loud rock and techno. I find that triode mode is clean enough without it, and it may remove some subtle details from the music.
Triode mode offers the lowest distortion, the lowest output impedance, but the lowest gain and power output. Because of the low output impedance it is the most tolerant of speakers with a wild impedance curve. A Simple SE will deliver 5 to 7 watts in triode mode.
UL mode is a compromize that is somewhere between triode and pentode mode. Proponents say that it delivers the power of pentode mode, with the distortion of triode mode. It acts like a form of negative feedback since the signal being fed into G2 is out of phase with the drive signal on G1.
In reality UL operation is more dependent on the speaker load, since the output impedance is considerably higher than triode mode. Output power and distortion are higher than triode mode. Your results will depend on how well the amplifier likes the load presented by your speakers. A Simple SE can make 10 to 14 watts in UL mode. CFB may work wonders in this mode on some speakers.
Pentode mode makes the most power, has the highest gain, but also has the highest distortion and output impedance. It is possible to use pentode mode for HiFi applications, but it usually requires both local feedback (like CFB) and global feedback (a loop around the entire amp) to bring the distortion and output impedance down. Pentode mode is highly dependent on the speaker load. It is often used in guitar amps for this reason. This is why the characteristic sound of a certain amp depends on the amplifier circuitry AND the speaker characteristics. I have seen a SimpleSE make 20 watts in pentode mode but it didn't sound good for HiFi. The bass was all muddy and boomy. It absolutely screamed when fed by my guitar preamp.
It would appear that the IXYS DSEI 12-12A parts have a problem in this application. I have used them without issue in my other amplifiers. I will begin the search for another part.
Metallica at 3 AM, your neighbors must love it!
tubelab.com said:
George,
I used the same SS diodes, and one of mine failed also. No problems with an old GZ34 stolen from my 'spare' ST70. I plan on staying with the tube rectifier.
With the Allied power xformer and triode-wired EL34's, I get 440 V B+, 420 V at the plate, and 31 V across the 560 Ohm cathode resistor. That should mean about 55 mA bias current, and 21W dissipation. Does that seem about right, or is it a little conservative?
Bill
Thanks George. As always your responses are thorough and put into laymen's terms. I guess I'll start wiring up some switches to give me all the options. I'm kindof crazy with what I listen to. Primarily heavy metal but also acid jazz (David Fiuzynski is awesome on this amp), classical, etc.
I'm trying to convert my neighbors kid's from wrap to heavy metal. All I hear from them is thump, thump...
Andy
I'm trying to convert my neighbors kid's from wrap to heavy metal. All I hear from them is thump, thump...
Andy
Wired TR/UL switch. I seem to like triode mode better. My speakers are 93db @ 1 watt. It looks like the power should off when switching modes though? I noticed the cones get blasted on the speakers when switching.
I also notice this thing is DEAD quiet in triode mode. Unless it has something to do with me fiddling with the wires. I put the volume up full with no input, put my ear next to the speaker and I hear nothing.
I also notice this thing is DEAD quiet in triode mode. Unless it has something to do with me fiddling with the wires. I put the volume up full with no input, put my ear next to the speaker and I hear nothing.
Regarding the blowing diodes, found this on DIYTube http://www.diytube.com/phpBB2/viewtopic.php?t=493
Looks like they have been having trouble with high voltage spikes blowing diodes with standby switches that make/break the HT centre tap of the transformer to ground. Unfortunately I do not have a spare rectifier tube at the moment, waiting for some to arrive in the mail, so I think I might just stay with no solid state diodes and disconnect the standby switch while I wait. This info might be useful to you George.
Cheers!
Chris.
PS, having to listen to my solid state amp now while I wait. I used to think it sounded good, now I am busting to get my SimplSE on line again!
Looks like they have been having trouble with high voltage spikes blowing diodes with standby switches that make/break the HT centre tap of the transformer to ground. Unfortunately I do not have a spare rectifier tube at the moment, waiting for some to arrive in the mail, so I think I might just stay with no solid state diodes and disconnect the standby switch while I wait. This info might be useful to you George.
Cheers!
Chris.
PS, having to listen to my solid state amp now while I wait. I used to think it sounded good, now I am busting to get my SimplSE on line again!
Chris,
Sorry to hear that you have to wait. I know what you mean about listening to SS after this amp. I wired in the CFB/NO CFB switch and I can now say I like the triode mode with no CFB. I am going to replace my Fountek Altitude 3500 amp with this. The only problem I have is that there is one input. I was thinking of building the Aikido preamp. Does that sound like a good idea? Really all I need is a way to select multiple input devices.
Sorry to hear that you have to wait. I know what you mean about listening to SS after this amp. I wired in the CFB/NO CFB switch and I can now say I like the triode mode with no CFB. I am going to replace my Fountek Altitude 3500 amp with this. The only problem I have is that there is one input. I was thinking of building the Aikido preamp. Does that sound like a good idea? Really all I need is a way to select multiple input devices.
awhite1159 said:
Do you need more gain or drive? If so, the Aikido is great.
BTW, what is the sensitivity and gain of the SimpleSE? I have an Aikido linestage. It sounds great, but it is overkill and too much gain for my EL34 PP amp. I may try to break it down and build something simplier, but I am also interested in building this SimpleSE.
If extra gain isn't needed by the SimpleSE, then I may rebuild the Aikido into something simplier with less gain.
Jayme,
I'm glad you asked that question. I am now more concerned about having a line stage if it will help. Please let me explain.
I don't need additional gain. Or, at least I think I don't. It seems that the output from my tuner is much lower and it sounds really great. But when I switch the cables to use my CD player, it seems to sound clipped and might even have some harmonics being produced. What's interesting is that this clipping appears even when the volume is low on the SimpleSE amp. I conclude from this that it is possible I am overdriving the 12AT7. Would a line stage control the input level to keep it consistent. Is my assumption correct?
I'm glad you asked that question. I am now more concerned about having a line stage if it will help. Please let me explain.
I don't need additional gain. Or, at least I think I don't. It seems that the output from my tuner is much lower and it sounds really great. But when I switch the cables to use my CD player, it seems to sound clipped and might even have some harmonics being produced. What's interesting is that this clipping appears even when the volume is low on the SimpleSE amp. I conclude from this that it is possible I am overdriving the 12AT7. Would a line stage control the input level to keep it consistent. Is my assumption correct?
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