Hi guys, this is my first post here. Just escaped from the AA forum.
I am going to need help with this project, as I have never built any amps before, at least not from scratch. I have built a phono kit and my Audio Note M3 preamp kit.
http://www.audionotekits.com/line.html
I have been using it with a pair of DIY PP KT88 mono blocs that was not built by me. They have been pretty good sound wise, at least so I thought, until I tried a little Dared MP7 6l6 SET, from my office system with the better stuff in the tube room.
I couldn't believe the difference this little 6watt intergrated amp was making , driving 90db PMC FB1+ speakers in a 12X14 room.
I put it in there a month ago and its still there.
So I have decided that I want a nice pair of SET monos, and that I would like to build them myself, as there is not much mono bloc kits to choose from, and the Audio Note kit is just too expensive.
I also decided that I just want to do a good 300B design and be done. I don't want to be upgrading something every month, at least nothing major. So I want to use mostly the good parts.
I have been doing a lot of reading and I think I am about 70% literate as to how these various tube schematic work. The math part will take much longer. So I am looking for something simple and trouble free, that will work nicely with the AN preamp.
I have tried to narrow down my choice to these two that I found.
http://www.tubelab.com/TubelabSE.htm
or the Andrea Ciuffoli 5842-inter for single 300b on this site:
http://www.simpletube.com/databank/data_down.htm
Please feel free to suggest any other or better ideas.
In the mean time I would like to go ahead and start ordering the transformers, so here are my choices:
Hammond 374BXP for the powers
Electra Print 3.5K 120ma 20w 8ohm for the outputs
I think these may be a little overkill specs wise, but I figure better safe than sorry incase I should want to go PSE some day.
The smaller stuff I can decide on as the time comes.
So that it for a start, I think. All help is welcome.
I am going to need help with this project, as I have never built any amps before, at least not from scratch. I have built a phono kit and my Audio Note M3 preamp kit.
http://www.audionotekits.com/line.html
I have been using it with a pair of DIY PP KT88 mono blocs that was not built by me. They have been pretty good sound wise, at least so I thought, until I tried a little Dared MP7 6l6 SET, from my office system with the better stuff in the tube room.
I couldn't believe the difference this little 6watt intergrated amp was making , driving 90db PMC FB1+ speakers in a 12X14 room.
I put it in there a month ago and its still there.
So I have decided that I want a nice pair of SET monos, and that I would like to build them myself, as there is not much mono bloc kits to choose from, and the Audio Note kit is just too expensive.
I also decided that I just want to do a good 300B design and be done. I don't want to be upgrading something every month, at least nothing major. So I want to use mostly the good parts.
I have been doing a lot of reading and I think I am about 70% literate as to how these various tube schematic work. The math part will take much longer. So I am looking for something simple and trouble free, that will work nicely with the AN preamp.
I have tried to narrow down my choice to these two that I found.
http://www.tubelab.com/TubelabSE.htm
or the Andrea Ciuffoli 5842-inter for single 300b on this site:
http://www.simpletube.com/databank/data_down.htm
Please feel free to suggest any other or better ideas.
In the mean time I would like to go ahead and start ordering the transformers, so here are my choices:
Hammond 374BXP for the powers
Electra Print 3.5K 120ma 20w 8ohm for the outputs
I think these may be a little overkill specs wise, but I figure better safe than sorry incase I should want to go PSE some day.
The smaller stuff I can decide on as the time comes.
So that it for a start, I think. All help is welcome.
I would go with the Tubelab boards, George has put a lot of effort into this design and it sounds good, plus you will have all the assistance you could need to get it running.
The 374BX is a good choice for power transformer, the 300 series stuff is quiet, and doesn't run particularly warm on 60Hz even at currents approaching its ratings.
I have had Jack at Electra-Print wind me transformers in the past and have been quite pleased with the result.
I don't recommend PSE with 300B as the PSE amplifiers I have encountered seem to loose something to the single tube amp, and the chosen output transformers are not going to be suitable due to need for half the primary impedance and twice the standing current for PSE as opposed to SE.
I have had good luck with JJ 300B so far, but my samples are vintage 2001 or thereabouts.. Buy from a reputable vendor matched and burned in. Others have been more problematic, stay away from sed/svetlana/ =C= 300B as I have had terrible problems with them shorting grid to filament.
Frankly PSE gives you just 3dB more power which IMO is not enough to make it worthwhile. I am currently working on the design for the eventual replacement for my 300B SE amplifier and have targeted 6dB as the required power increase in my application. I will most likely use VT4C/211/4C21 or 845 to achieve this power level.
The 374BX is a good choice for power transformer, the 300 series stuff is quiet, and doesn't run particularly warm on 60Hz even at currents approaching its ratings.
I have had Jack at Electra-Print wind me transformers in the past and have been quite pleased with the result.
I don't recommend PSE with 300B as the PSE amplifiers I have encountered seem to loose something to the single tube amp, and the chosen output transformers are not going to be suitable due to need for half the primary impedance and twice the standing current for PSE as opposed to SE.
I have had good luck with JJ 300B so far, but my samples are vintage 2001 or thereabouts.. Buy from a reputable vendor matched and burned in. Others have been more problematic, stay away from sed/svetlana/ =C= 300B as I have had terrible problems with them shorting grid to filament.
Frankly PSE gives you just 3dB more power which IMO is not enough to make it worthwhile. I am currently working on the design for the eventual replacement for my 300B SE amplifier and have targeted 6dB as the required power increase in my application. I will most likely use VT4C/211/4C21 or 845 to achieve this power level.
Kevin, thanks for your reply, I am leaning more to the Tubelab SE for the reasons you listed and also because I am only about 10 miles south of him. So if I REALLY need help I could just run up there.
I am going to ask him if posible he could draw me a mono schematic with out the volume and selector switches. I want to do point to point so I can change the layout a bit
I was thinking EH300Bs, but I will check out the JJ. I didn't know I could get them burnt in.
I don't think I will need PSE judging from how the 6watt plays now. I would like to get about 10 watts per ch out of the 300b however.
So the transformer choices will be Ok ?
Thanks again,
AB.
I am going to ask him if posible he could draw me a mono schematic with out the volume and selector switches. I want to do point to point so I can change the layout a bit
I was thinking EH300Bs, but I will check out the JJ. I didn't know I could get them burnt in.
I don't think I will need PSE judging from how the 6watt plays now. I would like to get about 10 watts per ch out of the 300b however.
So the transformer choices will be Ok ?
Thanks again,
AB.
Hi audiobliss,
You'll not get to quite to 10W with 300B with currently acceptable levels oflinearity in most conventional SE amplifier circuits, if you want decent tube life, but 8W is readily achievable and the difference is not significant. And I suspect the power drive circuitry will help in this regard.
Depending on your level of experience you would probably be better off buying and assembling the PCB.. George has taken most of the guess work out of appropriate component placement, and you probably have less freedom in placement than you suspect for good performance..
The sockets can always be placed on the top of the chassis and wired to the board if you want some flexibility.
One other tube to consider would be the TJ 300B premium meshplate, it's quite nice sounding.
Your transformer choices should be fine, but if you build the tubelab SE you should consult George for his recommendation.
You'll not get to quite to 10W with 300B with currently acceptable levels oflinearity in most conventional SE amplifier circuits, if you want decent tube life, but 8W is readily achievable and the difference is not significant. And I suspect the power drive circuitry will help in this regard.
Depending on your level of experience you would probably be better off buying and assembling the PCB.. George has taken most of the guess work out of appropriate component placement, and you probably have less freedom in placement than you suspect for good performance..
The sockets can always be placed on the top of the chassis and wired to the board if you want some flexibility.
One other tube to consider would be the TJ 300B premium meshplate, it's quite nice sounding.
Your transformer choices should be fine, but if you build the tubelab SE you should consult George for his recommendation.
Kevin,
My main reason for wanting to do point to point was so I could change the tube placements. I thought of placing them on the top plate and wiring them to the board, as you suggest, but I was not too sure if that would be a good idea. So thanks for clearing that up.
Are the TJ meshplates the same as the Sophia meshplates ?
Who makes the TJ?
Evenharmonics,
I had read you post when you first started it, but I didn't know how you ended up with the project. I see you are using 2A3, would the same changes apply to the 300B.
What did you do about the switches? I do not need them and would like to bypass them.
I want to do mono blocs because my system is already set up and runing that way. Amp stands down by the speakers, fed by long interconnects and power cords.
Its all a little more work, but well worth it.
Thanks for the tip on the PT.
AB.
My main reason for wanting to do point to point was so I could change the tube placements. I thought of placing them on the top plate and wiring them to the board, as you suggest, but I was not too sure if that would be a good idea. So thanks for clearing that up.
Are the TJ meshplates the same as the Sophia meshplates ?
Who makes the TJ?
Evenharmonics,
I had read you post when you first started it, but I didn't know how you ended up with the project. I see you are using 2A3, would the same changes apply to the 300B.
What did you do about the switches? I do not need them and would like to bypass them.
I want to do mono blocs because my system is already set up and runing that way. Amp stands down by the speakers, fed by long interconnects and power cords.
Its all a little more work, but well worth it.
Thanks for the tip on the PT.
AB.
TJ makes its own tubes and also makes tubes for several other resellers including I believe Sophia.
TJ stands for Tian Jin, and is a well regarded manufacturer of exotic dhts..
Here is a link to the factory tour: http://www.diyhifisupply.com/diyhs_tj-factory-trip.htm
Diy Hifi Supply is also a good place to purchase these tubes, although there are some dealers in the US as well.
TJ stands for Tian Jin, and is a well regarded manufacturer of exotic dhts..
Here is a link to the factory tour: http://www.diyhifisupply.com/diyhs_tj-factory-trip.htm
Diy Hifi Supply is also a good place to purchase these tubes, although there are some dealers in the US as well.
My 300B is by Valve Art purchased from Antique Electronics Supply (only online store I found that sells single 300B at decent price) and OPT is Hammond 1627SEA. This combo sounds good. It's for my center channel of surround sound system with TubelabSE stereo (w/ Electra-print OPT) powering up the mains.
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