I started building a tubelab.com Simple (space) SE amp this weekend and took a couple photos.
Album here: http://picasaweb.google.com/rkevans.bb/BuildingATubelabComSimpleSETubeAmplifier
Rick
Album here: http://picasaweb.google.com/rkevans.bb/BuildingATubelabComSimpleSETubeAmplifier
Rick
Nice photo journal. I love when people document their builds. You've done a nice job with the build, and the pictures are good too.
I hate to be the one to break the bad news, but your 5AR4 is dead. It has air in it. The getter flash has turned all white. Don't try to power up the amp until you replace that tube.
I hate to be the one to break the bad news, but your 5AR4 is dead. It has air in it. The getter flash has turned all white. Don't try to power up the amp until you replace that tube.
Well, naturally my 5AR4 is dead. I have (almost) enough parts to build two complete amp boards, including a second PCB.
Two drivers, two pair of output tubes.
But only one 5AR4. "It should outlast the other tubes." Wrong. It was VERY tight-fitting when I put it in the socket. I tried a few times, and everything lines up, so I just sorta pushed a bit harder and it finally fell into place.
What the photos don't show is a small crack by the base... Time to order a new one (and a spare this time).
Whoops.
Rick
Two drivers, two pair of output tubes.
But only one 5AR4. "It should outlast the other tubes." Wrong. It was VERY tight-fitting when I put it in the socket. I tried a few times, and everything lines up, so I just sorta pushed a bit harder and it finally fell into place.
What the photos don't show is a small crack by the base... Time to order a new one (and a spare this time).
Whoops.
Rick
Where did I put that duct tape?
Ty,
I like the duct tape idea. I was going to keep the dead tube either way, just as a reminder and for 'show and tell'.
A replacement pair of rectifier tubes (Another JJ and a Sovtek spare) should ship from AES tomorrow. The only 'big' item left on my shopping list is a pair of Edcor OPTs. Then I need to start thinking seriously about designing an enclosure.
Rick
Ty,
I like the duct tape idea. I was going to keep the dead tube either way, just as a reminder and for 'show and tell'.
A replacement pair of rectifier tubes (Another JJ and a Sovtek spare) should ship from AES tomorrow. The only 'big' item left on my shopping list is a pair of Edcor OPTs. Then I need to start thinking seriously about designing an enclosure.
Rick
Re: My first SE OPT
If I had to buy something in the next 10 minutes, it would be:
The 'surprisingly good value' XSE15 for $20 each.
I've also considered:
The GXSE 'slight upgrade for $10 more' from Edcor.
The CXSE 'bigger upgrade for 4x the price' from Edcor.
The Hammond 1628 'safe choice, and pretty good iron' for $100ish each. I'm using the Allied power tranny and a Hammond filter choke, so this would really complete the set.
The 'economy Transcendar' on Ebay for $112 per pair (w/ shipping). Lack of a 40% tap and limited reviews eliminated this one. George seems very pleased with his Transcendar OPTs, but he has the 'no longer available' version from a few years ago.
The UBT-2 from One Electron at $110 each. Haven't seen many reviews/mentions of these, but the ones I've seen have been uniformly positive.
At some point, I became overwhelmed by the options and couldn't make a choice. I can't apply power to the project for initial testing until I buy something. So I've decided to go with the 'it will work, it's cheap, stop looking' solution.
I expect to replace them later with something nice, and these can be recycled into a second project.
But for now, I'm more concerned with applying power to the amp and finally being able to listen to my exhaustive collection of polka songs on 8-track.
Rick
P.S. I'm kidding about the polka. It's all disco.
Ty_Bower said:
If I had to buy something in the next 10 minutes, it would be:
The 'surprisingly good value' XSE15 for $20 each.
I've also considered:
The GXSE 'slight upgrade for $10 more' from Edcor.
The CXSE 'bigger upgrade for 4x the price' from Edcor.
The Hammond 1628 'safe choice, and pretty good iron' for $100ish each. I'm using the Allied power tranny and a Hammond filter choke, so this would really complete the set.
The 'economy Transcendar' on Ebay for $112 per pair (w/ shipping). Lack of a 40% tap and limited reviews eliminated this one. George seems very pleased with his Transcendar OPTs, but he has the 'no longer available' version from a few years ago.
The UBT-2 from One Electron at $110 each. Haven't seen many reviews/mentions of these, but the ones I've seen have been uniformly positive.
At some point, I became overwhelmed by the options and couldn't make a choice. I can't apply power to the project for initial testing until I buy something. So I've decided to go with the 'it will work, it's cheap, stop looking' solution.
I expect to replace them later with something nice, and these can be recycled into a second project.
But for now, I'm more concerned with applying power to the amp and finally being able to listen to my exhaustive collection of polka songs on 8-track.
Rick
P.S. I'm kidding about the polka. It's all disco.
Note to self: Emailing Edcor to order stuff is really slow, they won't respond for 4 days. Calling them seems to work better.
Finally made a decision and bought a pair of the GXSE15-8-5K 'guitar amp' OPT thingies. No particular reason, I was just a little nervous about ordering the 'cheapest option'.
Discovered replacement GZ34/5AR4 tubes in my mailbox today, along with a 'Fender' branded (Russia, Electro-Harmonix) 12AT7. The last one was a complete impulse purchase.
I was a little surprised by the obvious differences in construction of the EH/F 12AT7 tube, compared to one from JJ. I would not be surprised at all if those little things sound different. The rectifier tubes look pretty similar internally, but the Sovtek one (my new spare) is 10-15% shorter than the JJ. This is all very neat, despite being mildly confusing.
Added the Magnequest 'Robin Hood' OPTs to my shopping list for later ( http://www.magnequest.com/robin_hood_series.htm ). That was after seeing several well-informed posts by 'MQraciing' while searching the archives.
In other news, the Mouser order also arrived this week, so I soldered in the final three resistors (3W metal-oxide). Not a huge amount of progress, but every little step helps.
Now I just need to find a couple feet of hook-up wire and a few switches...
Rick
Finally made a decision and bought a pair of the GXSE15-8-5K 'guitar amp' OPT thingies. No particular reason, I was just a little nervous about ordering the 'cheapest option'.
Discovered replacement GZ34/5AR4 tubes in my mailbox today, along with a 'Fender' branded (Russia, Electro-Harmonix) 12AT7. The last one was a complete impulse purchase.
I was a little surprised by the obvious differences in construction of the EH/F 12AT7 tube, compared to one from JJ. I would not be surprised at all if those little things sound different. The rectifier tubes look pretty similar internally, but the Sovtek one (my new spare) is 10-15% shorter than the JJ. This is all very neat, despite being mildly confusing.
Added the Magnequest 'Robin Hood' OPTs to my shopping list for later ( http://www.magnequest.com/robin_hood_series.htm ). That was after seeing several well-informed posts by 'MQraciing' while searching the archives.
In other news, the Mouser order also arrived this week, so I soldered in the final three resistors (3W metal-oxide). Not a huge amount of progress, but every little step helps.
Now I just need to find a couple feet of hook-up wire and a few switches...
Rick
I am using the XSE15-4-5K output transformers in my Simple SE. I have an active crossover and sep SS amp and woofers for the sub 80Hz though. I am very happy with the result. I have a pair of the GSXE ready to try in my next SE build.
Just a question, I noticed that you built the board with all of the components on the top. This makes it difficult to have those lovely looking valves on display without exposing the dangerous connections, cct board etc. Any particular reason?
Anyway, you will love the sound of this amp!
Chris
Just a question, I noticed that you built the board with all of the components on the top. This makes it difficult to have those lovely looking valves on display without exposing the dangerous connections, cct board etc. Any particular reason?
Anyway, you will love the sound of this amp!
Chris
chrish said:
That sounds similar to my intended system. A pair of Fostex full range drivers in a back-loaded horn (being built), and a sub or two for all the missing bass (no progress yet).
The GXSE upgrade was literally a last minute decision. I just kept thinking about the 'size matters' comments from previous discussions of OPT performance. So, I wanted a little more iron for a little more money.
What are you using for an active crossover?
I have cats. So, I'm going to have to cover all the hot bits with a cage to protect them no matter how I mount the circuit board. Once I made that decision, it was small leap to realize that since I actually liked the look of the circuit board, I wanted it to be visible too.
I'll update the photo gallery soon to show progress, tube comparisions and my US$3.50 cage idea (actually George's idea, but I'm using it).
I certainly hope I like the sound of this thing. Because I feel like a complete nutter for building it.
Rick
Just a comment from another Simple SE builder - I picked the CXSE transformers and they do sound excellent. I believe I saw reviews comparing them to equivalent Hammonds and they had better specs as well as a better price.
I certainly don't have any lack of bass, either (especially when operating in UL mode) and I do listen to Electronic/Techno/Trance. I'm not sure if the smaller Edcors just lack the bass response of the larger ones, or if insufficient bass means to some that one normally has tone controls tweaked upward for bass. These results were also with a set of rather inefficient speakers. I'm currently running the EH KT88's and they are said to have good bass, so that could be another factor.
I suppose I'm curious if there is that much difference between the various sized transformers' bass response - George has tested them all and maybe he will have some comments on that.
The one thing I feel that I have left to do is build a DC blocker on the incoming AC to quiet the power transformer hum. The amp is silent from a set of ~94dB speakers.
As a sidenote, the overall sound is sweet. I started with the amp wired in UL and then when I installed the switch so I could choose modes I realized how much better some things sound in triode. It was a second wave of excitement about the sound!
I certainly don't have any lack of bass, either (especially when operating in UL mode) and I do listen to Electronic/Techno/Trance. I'm not sure if the smaller Edcors just lack the bass response of the larger ones, or if insufficient bass means to some that one normally has tone controls tweaked upward for bass. These results were also with a set of rather inefficient speakers. I'm currently running the EH KT88's and they are said to have good bass, so that could be another factor.
I suppose I'm curious if there is that much difference between the various sized transformers' bass response - George has tested them all and maybe he will have some comments on that.
The one thing I feel that I have left to do is build a DC blocker on the incoming AC to quiet the power transformer hum. The amp is silent from a set of ~94dB speakers.
As a sidenote, the overall sound is sweet. I started with the amp wired in UL and then when I installed the switch so I could choose modes I realized how much better some things sound in triode. It was a second wave of excitement about the sound!
I chose the XSE transformers after emailing George and telling him that I was running an active crossover. His opinion was that for the mids and highs, the XSE was hard to beat. I was willing to pay more if required... The GSXE was not available at the time. My limited reading suggests that you need more iron for lower freqs. As with most things, there is a compromise, and good low end with big iron can mean not quite so good highs.
I am using Rod Elliots crossover http://sound.westhost.com/project09.htm
I am moving to an apartment with my girlfriend in a few months, and (surprise surprise) she does not appreciate the beauty of my twin 100 litre woofer units! Will have to either convince her to let me keep them, or build an amp with a little better bass response. I could either change the output transformers, or build a whole new amp. Found some nice looking chassis in Singapore that look pretty good to replace the Hammond box with. Or I can wait for the Simple PP, have some nice Tamura PP transformers waiting for a project!
As for the cats, I would not worry too much. Cats are not as smart as dogs, but they will soon learn that the valves are too hot to touch! When my kids stay with me they sometimes bring their cat with them and I have had no problems.
Cheers,
Chris
I am using Rod Elliots crossover http://sound.westhost.com/project09.htm
I am moving to an apartment with my girlfriend in a few months, and (surprise surprise) she does not appreciate the beauty of my twin 100 litre woofer units! Will have to either convince her to let me keep them, or build an amp with a little better bass response. I could either change the output transformers, or build a whole new amp. Found some nice looking chassis in Singapore that look pretty good to replace the Hammond box with. Or I can wait for the Simple PP, have some nice Tamura PP transformers waiting for a project!
As for the cats, I would not worry too much. Cats are not as smart as dogs, but they will soon learn that the valves are too hot to touch! When my kids stay with me they sometimes bring their cat with them and I have had no problems.
Cheers,
Chris
I am using the CXSE and I am very pleased with the bass. George suggested them because of their weight and response and I think for the money they fit my build .I have somewhat inefficent speakers @89dB and with EL34's I am still pleased with the results. In my future there will be some KT88's also to swap around with. The mids and highs with my combo are very strong and clean. There is no hum present at the speaker cones with no buzzing from my PT which is an Allied.
BTW, Rick I wish that I had documented my build, nice photo's.
BTW, Rick I wish that I had documented my build, nice photo's.
Hammond 1628SEA's here. These are supposed to be a big improvement over the 1628SE's that had a hard time with the higher frequencies. I have no complaints, and they, along with the rest of my SimpleSE sound fantastic. I have a real Marantz 8b to use as a reference, and the SimpleSE is better by a long shot in my opinion.
Worked on the amp a little more this weekend. A few thoughts --
1. I hate chassis-mount IEC jacks. I have two styles and they both suck. One of them makes it insanely difficult to install a fuse, and the other one needs two fuses to operate.
2(a). Requiring 5x20mm 'Euro' style fuses is a bad idea when you're troubleshooting (i.e. blowing a few fuses) on a weekend. When available at all, the selection is horrible (rare to find a slow-blow) and prices are insane. Pack of 6, assorted, one 2A slow-blow = US$8 at a local retailer.
2(b). I actually resorted to Radio Shack, and found a salesman who wasn't an idiot. RS actually turned out to be a GOOD source, despite a history of driving me insane. Four fuses (5x20 2A/3A slow-blow) for $3. I bought them all. They didn't demand my address, phone number, email address and birthdate before allowing me to pay in cash. Did I wake up in a parallel universe or something?
3. Rectifiers hate me. I broke a 5AR4 earlier, the replacement JJ blows fuses, and one or both of my 'hexfred' diodes seems bad.
4. Wired the whole thing up, made everything neat. Checked everything twice, then applied power. Blew a fuse within a second. Burned a few gallons of gas trying to find more fuses, thinking that the problem was just in-rush current and a slow-blow would help.
Blew another handful of fuses while troubleshooting. Disconnected the high-voltage section and it works (heater elements glow). Verified the HV secondary put out voltage with an open circuit -- yes.
Disconnected everything and removed the circuit board from the temp. chassis. Started probing with an multimeter, looking for weird readings. One of my probes broke. Bought more probes, and decided I didn't trust the ohm readings from this old meter anymore. Changed the 9V battery, and it's still acting funny. Let me think... think... Yeah, I got this thing 'free with an order over $50' about 6 years ago... (http://www.web-tronics.com/freedmmoffer.html -- different model than I have, but roughly the same quality). Threw it in the trash.
Went to bed.
Sunday morning, drove to Harbor Freight and bought 4 new multimeters for US$ 15 (total).
Probed some more, connected everything and blew a couple more fuses. Removed R1 to isolate the power section from the rest of the circuit. Still blows fuses. Removed the 5AR4 and jumpered SW1 to force it use the hexfreds. Still blows fuses. Removed the SS diodes from the board, installed the JJ 5AR4. Still blows fuses. Replaced the JJ 5AR4 with a Sovtek. Everything glows, fuses don't blow.
Reinstalled R1 and wired the board back up (no speakers connected). Fuse doesn't blow. Took a picture (added to gallery above). Removed 6L6 tubes and the 12AT7, installed my 'spares', still works. The 'blue glass' JJ EL34 tubes are definitely assembled with the glass crooked. That's starting to bother me.
Removed all the tubes. Put project on a shelf for later.
What a frustrating weekend!
Rick
1. I hate chassis-mount IEC jacks. I have two styles and they both suck. One of them makes it insanely difficult to install a fuse, and the other one needs two fuses to operate.
2(a). Requiring 5x20mm 'Euro' style fuses is a bad idea when you're troubleshooting (i.e. blowing a few fuses) on a weekend. When available at all, the selection is horrible (rare to find a slow-blow) and prices are insane. Pack of 6, assorted, one 2A slow-blow = US$8 at a local retailer.
2(b). I actually resorted to Radio Shack, and found a salesman who wasn't an idiot. RS actually turned out to be a GOOD source, despite a history of driving me insane. Four fuses (5x20 2A/3A slow-blow) for $3. I bought them all. They didn't demand my address, phone number, email address and birthdate before allowing me to pay in cash. Did I wake up in a parallel universe or something?
3. Rectifiers hate me. I broke a 5AR4 earlier, the replacement JJ blows fuses, and one or both of my 'hexfred' diodes seems bad.
4. Wired the whole thing up, made everything neat. Checked everything twice, then applied power. Blew a fuse within a second. Burned a few gallons of gas trying to find more fuses, thinking that the problem was just in-rush current and a slow-blow would help.
Blew another handful of fuses while troubleshooting. Disconnected the high-voltage section and it works (heater elements glow). Verified the HV secondary put out voltage with an open circuit -- yes.
Disconnected everything and removed the circuit board from the temp. chassis. Started probing with an multimeter, looking for weird readings. One of my probes broke. Bought more probes, and decided I didn't trust the ohm readings from this old meter anymore. Changed the 9V battery, and it's still acting funny. Let me think... think... Yeah, I got this thing 'free with an order over $50' about 6 years ago... (http://www.web-tronics.com/freedmmoffer.html -- different model than I have, but roughly the same quality). Threw it in the trash.
Went to bed.
Sunday morning, drove to Harbor Freight and bought 4 new multimeters for US$ 15 (total).
Probed some more, connected everything and blew a couple more fuses. Removed R1 to isolate the power section from the rest of the circuit. Still blows fuses. Removed the 5AR4 and jumpered SW1 to force it use the hexfreds. Still blows fuses. Removed the SS diodes from the board, installed the JJ 5AR4. Still blows fuses. Replaced the JJ 5AR4 with a Sovtek. Everything glows, fuses don't blow.
Reinstalled R1 and wired the board back up (no speakers connected). Fuse doesn't blow. Took a picture (added to gallery above). Removed 6L6 tubes and the 12AT7, installed my 'spares', still works. The 'blue glass' JJ EL34 tubes are definitely assembled with the glass crooked. That's starting to bother me.
Removed all the tubes. Put project on a shelf for later.
What a frustrating weekend!
Rick
Sorry to hear about the frustrations. It's always nice to read the stories of "powered it up, worked first try" - but sometimes it doesn't always happen.
I was working on a stereo push/pull EL84 amp where the two terminals for the output transformers' B+ connection was right next to the ground connection for the PT's center tap. Of course, I've got red wires on all three of them and managed to mis-land things. It blew fuses in about three seconds after the IRCL warmed up. After the second fuse went, I flipped the whole thing over to try to probe it with the volt meter. Slipped the probe between the line cord and chassis ground (stupid). Big zot, a little bit of scared, and a tripped circuit breaker. I finally stepped back, took a look at the wiring diagram again, and realized what a dumb thing I had done.
You must have a short somewhere in the high voltage section to be blowing fuses so fast. Maybe a stray wire is sneaking out of one of the Phoenix connectors, or you've got a solder whisker somewhere on the board where it doesn't belong. I'd post a hi-res photo of both sides of your completed circuit board if you can. Maybe someone can spot the mistake.
Good luck, and don't lose hope.
I was working on a stereo push/pull EL84 amp where the two terminals for the output transformers' B+ connection was right next to the ground connection for the PT's center tap. Of course, I've got red wires on all three of them and managed to mis-land things. It blew fuses in about three seconds after the IRCL warmed up. After the second fuse went, I flipped the whole thing over to try to probe it with the volt meter. Slipped the probe between the line cord and chassis ground (stupid). Big zot, a little bit of scared, and a tripped circuit breaker. I finally stepped back, took a look at the wiring diagram again, and realized what a dumb thing I had done.
You must have a short somewhere in the high voltage section to be blowing fuses so fast. Maybe a stray wire is sneaking out of one of the Phoenix connectors, or you've got a solder whisker somewhere on the board where it doesn't belong. I'd post a hi-res photo of both sides of your completed circuit board if you can. Maybe someone can spot the mistake.
Good luck, and don't lose hope.
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