I have wanted to build a set of single ended mono blocks for about a decade now. The cycle goes like this: I look into it; I get excited; then I start to attempt to gather the necessary knowledge to safely and effectively pull it off; I get overwhelmed and discouraged; I stall out and the cycle starts back up a year or two later.
This time I have made it further than I have ever made it before. (Thank you youtube.) This time I have decided to build Herb Reichert's mono blocks found here: Flesh and Blood, The Reichert 300B By Herbert Reichert
I trust Herb's ears because I have read his articles and reviews in Stereophile Magazine. In the article, Herb goes into great detail about the parts to use, which I can really appreciate. I want the thing to sound great. The only problem is, the output transformer is a Tango and Tango went out of business. There is another company, ISO, that purports to be run by the employees of Tango. However, I have no way of knowing if that is true or not and it's difficult to get the parts even if it is true.
Herb's schematic leaves something to be desired. Some of the hand-written parts are illegible.
Can anyone please help with these two issues?
Thanks in advance,
Adam
This time I have made it further than I have ever made it before. (Thank you youtube.) This time I have decided to build Herb Reichert's mono blocks found here: Flesh and Blood, The Reichert 300B By Herbert Reichert
I trust Herb's ears because I have read his articles and reviews in Stereophile Magazine. In the article, Herb goes into great detail about the parts to use, which I can really appreciate. I want the thing to sound great. The only problem is, the output transformer is a Tango and Tango went out of business. There is another company, ISO, that purports to be run by the employees of Tango. However, I have no way of knowing if that is true or not and it's difficult to get the parts even if it is true.
Herb's schematic leaves something to be desired. Some of the hand-written parts are illegible.
Can anyone please help with these two issues?
Thanks in advance,
Adam
Tango XE60-5s is a 5K primary transformer. The single end 300B circuit as described run with a 425V plate and 80mA idle.
So you want a single-ended transformer (aka. not a push-pull) with a spec that are close to 5K, 90ma air gap that could handle ~10W or greater. There are number of them in the market. One example is Lundahl LL1623/90mA
So you want a single-ended transformer (aka. not a push-pull) with a spec that are close to 5K, 90ma air gap that could handle ~10W or greater. There are number of them in the market. One example is Lundahl LL1623/90mA
Hmm, don't wish to be discouraging but... first how experienced are you as regards electronics and valves/tubes? It's not the easiest amp for a first build and this sort of thing "The light from the streetlights mixes with the glow of the bright emitters in my listening room. Nyiregyhazi plays Liszt in front of me " and "You see, I believe most deeply that the real magic ingredient in any amp design is the wu of the designer." fills me with distrust.
It also uses a lot of boutique parts, I'm worried all you'll have at the end of it is empty pockets, a bag full of fancy audiophile components and a bad taste in the mouth.
Andy.
It also uses a lot of boutique parts, I'm worried all you'll have at the end of it is empty pockets, a bag full of fancy audiophile components and a bad taste in the mouth.
Andy.
The art of listening is different from the art of writing. Will this amp satisfy your range of music and taste? Not to mention speakers. It is far from universal.
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A very firm thumbs down from me. The "design" does not respect published limits. 
Look at the 5R4 data sheet. A 47 μF. 1st filter cap. is abusive, even if you factor sea level in vs. altitude.
Rant on. Get the Physics right! Rant off.
Look at the 5R4 data sheet. A 47 μF. 1st filter cap. is abusive, even if you factor sea level in vs. altitude.Rant on. Get the Physics right! Rant off.
I take that as a Collective Thumbs Down!!!
Thank you one and all for your help. It seems that the hive mind universally discourages me in attempting to build Herb's amp.
By way of an explanation for how and why I chose this amp, perhaps I can find a better way forward in your future responses. I would like to build a system based on horn loaded speakers driven by low wattage tubes. Right now I play through Klipsch SB2 bookshelf speakers. (I think their sensitivity is 92.) Mostly I play lps. Sometimes I stream music through Tidle. I don't require a great deal of volume. In fact I prefer the intimacy of quiet listening to the drama of a loud affair.
To that end, I want my amps to sound beautiful, elegant even. With no way of listening to examples of the amps I find online, I'm left to look to trusted sources. This initially led me to seek out reviews of amps, mostly in Stereophile and 6Moons. Then I would attempt to find a similar schematic for that amp. This search led me to Art Dudley's review of the Miyajima 2010 stereo amp found here: Listening #139 | Stereophile.com . I then found examples of the OTL amps like this Futterman style circuit: http://www.solaris.no/electronics/power_amp/tube-amp/futterstyle/6AS7_Futterman_OTL.gif
My experience with electronics is limited to repairs to my guitar amps. My '67 fender vibro champ has needed tlc over the years and I've been able to go out and find the right youtube video to aid in it's repair. I have a fair amount of experience in commercial and residential electrical contracting. I can wire a house start to finish. That being said, I know my limits. That is what has always given me pause over the years and kept me from making any attempts at building an amp. I've been watching some really well done educational videos on electronics here: YouTube . Perhaps I'm prepared to begin, perhaps not.
Again, Thank all of you for your input. I really do appreciate it.
AGW
Thank you one and all for your help. It seems that the hive mind universally discourages me in attempting to build Herb's amp.
By way of an explanation for how and why I chose this amp, perhaps I can find a better way forward in your future responses. I would like to build a system based on horn loaded speakers driven by low wattage tubes. Right now I play through Klipsch SB2 bookshelf speakers. (I think their sensitivity is 92.) Mostly I play lps. Sometimes I stream music through Tidle. I don't require a great deal of volume. In fact I prefer the intimacy of quiet listening to the drama of a loud affair.
To that end, I want my amps to sound beautiful, elegant even. With no way of listening to examples of the amps I find online, I'm left to look to trusted sources. This initially led me to seek out reviews of amps, mostly in Stereophile and 6Moons. Then I would attempt to find a similar schematic for that amp. This search led me to Art Dudley's review of the Miyajima 2010 stereo amp found here: Listening #139 | Stereophile.com . I then found examples of the OTL amps like this Futterman style circuit: http://www.solaris.no/electronics/power_amp/tube-amp/futterstyle/6AS7_Futterman_OTL.gif
My experience with electronics is limited to repairs to my guitar amps. My '67 fender vibro champ has needed tlc over the years and I've been able to go out and find the right youtube video to aid in it's repair. I have a fair amount of experience in commercial and residential electrical contracting. I can wire a house start to finish. That being said, I know my limits. That is what has always given me pause over the years and kept me from making any attempts at building an amp. I've been watching some really well done educational videos on electronics here: YouTube . Perhaps I'm prepared to begin, perhaps not.
Again, Thank all of you for your input. I really do appreciate it.
AGW
If the spec's for the SB2 are accurate, the 8 or so W. a SE 300B is sufficient. Whether the damping factor of a no NFB SE DHT amp is adequate for the speakers is another matter.
A 300B project is expensive. Given it's your 1st project, the downside risks are great enough to warrant trying something else. The cost of magnetics is the "big ticket" in a tube amp project. PP O/P transformers are much less costly than SE transformers, for a given power handling capability. There are all sorts of PP projects that are reasonably inexpensive to be found in the archives, starting with Ian's "Baby Huey" and my "El Cheapo".
Remember, to a certain extent, the reviewers "shill" for those who advertise. IMO, the credibility of Stereophile, 6 Moons, etc. is low. The more something costs, the better they like it. Don't buy "snake oil"!
A 300B project is expensive. Given it's your 1st project, the downside risks are great enough to warrant trying something else. The cost of magnetics is the "big ticket" in a tube amp project. PP O/P transformers are much less costly than SE transformers, for a given power handling capability. There are all sorts of PP projects that are reasonably inexpensive to be found in the archives, starting with Ian's "Baby Huey" and my "El Cheapo".
Remember, to a certain extent, the reviewers "shill" for those who advertise. IMO, the credibility of Stereophile, 6 Moons, etc. is low. The more something costs, the better they like it. Don't buy "snake oil"!
There are a few diyAudio regulars who have contributed well-regarded projects you might like to try. The big advantage to going this route is that you can ask questions right here and get quick answers.
Eli Duttman has already replied in this thread, and he has a really nice design called the El Cheapo, which is a push-pull 6AQ5 or 6V6 amp with the output tubes wired triode. I'm sure that would make your Klipsch speakers sing. It's a simple circuit but very well thought out. It does use a bit of negative feedback, but you can reduce it as an experiment, to see what that sounds like.
El Cheapo parts list: elcheapo.htm
Schematic: https://www.diyaudio.com/forums/tubes-valves/108399-date-el-cheapo-schematic-2.html#post1883565
Another great contributor is Tubelab (George) who has a printed circuit board called the SSE (Simple Single-Ended) amp. That's another very well thought out little amp design. The board can be configured to use a wide range of commonly available output tubes wired for your choice of triode or ultralinear (distributed load). You'll probably want to go with triode. I would recommend trying an EL34 wired triode, as I think that is one of the more euphonic sounding of the common output pentodes/beam tetrodes. Or you can use a 6550A or KT88 wired triode for a bit more power. Some also like the sound of the Russian 6P3S (something like a 6L6GB) when wired triode (I do). But that tube won't make much power single-ended. At any rate, George has helped many first time builders, and he has his own vendor section on this site.
Tubelab diyAudio vendor forum: https://www.diyaudio.com/forums/tubelab/
Tubelab.com SSE page: Tubelab SSE | Tubelab
Tubelab SSE Build Thread: Simple SE Build Thread
I hope that helps.
--
Eli Duttman has already replied in this thread, and he has a really nice design called the El Cheapo, which is a push-pull 6AQ5 or 6V6 amp with the output tubes wired triode. I'm sure that would make your Klipsch speakers sing. It's a simple circuit but very well thought out. It does use a bit of negative feedback, but you can reduce it as an experiment, to see what that sounds like.
El Cheapo parts list: elcheapo.htm
Schematic: https://www.diyaudio.com/forums/tubes-valves/108399-date-el-cheapo-schematic-2.html#post1883565
Another great contributor is Tubelab (George) who has a printed circuit board called the SSE (Simple Single-Ended) amp. That's another very well thought out little amp design. The board can be configured to use a wide range of commonly available output tubes wired for your choice of triode or ultralinear (distributed load). You'll probably want to go with triode. I would recommend trying an EL34 wired triode, as I think that is one of the more euphonic sounding of the common output pentodes/beam tetrodes. Or you can use a 6550A or KT88 wired triode for a bit more power. Some also like the sound of the Russian 6P3S (something like a 6L6GB) when wired triode (I do). But that tube won't make much power single-ended. At any rate, George has helped many first time builders, and he has his own vendor section on this site.
Tubelab diyAudio vendor forum: https://www.diyaudio.com/forums/tubelab/
Tubelab.com SSE page: Tubelab SSE | Tubelab
Tubelab SSE Build Thread: Simple SE Build Thread
I hope that helps.
--
A 300B amp wouldn't be my choice for a first tube project, especially given the price of the output tubes and (in this design) the Tango iron. I'm also not a fan of those kind of driver stages but to each his own.
Pre/Early internet days and before the existence of this site - I started my own DIY audio journey by modifying a Dynaco 70. And a Dynaco PAS-3. And fixing / upgrading a Scott tube integrated. And then - this was a big step after a lot of reading - building my own tube preamplifier using 71A tubes at the exact recommended RCA manual operating points, but with my own power supply.
That gave me enough confidence to start building tube amps, where I went with a push-pull 6B4G amplifier and then a single-ended 2A3, both used with high efficiency Stephens Coax drivers inside of a homebrew Jensen cabinet.
And if you do want to build a 300B amp - no problem there, it is a classic tube - then you could use Hammond 1628SEA or Edcor output iron. And something like the Allied Electronics power transformers and Triad chokes will cut some of the build price.
But a preamplifier, especially a linestage, is a great place to start.
Pre/Early internet days and before the existence of this site - I started my own DIY audio journey by modifying a Dynaco 70. And a Dynaco PAS-3. And fixing / upgrading a Scott tube integrated. And then - this was a big step after a lot of reading - building my own tube preamplifier using 71A tubes at the exact recommended RCA manual operating points, but with my own power supply.
That gave me enough confidence to start building tube amps, where I went with a push-pull 6B4G amplifier and then a single-ended 2A3, both used with high efficiency Stephens Coax drivers inside of a homebrew Jensen cabinet.
And if you do want to build a 300B amp - no problem there, it is a classic tube - then you could use Hammond 1628SEA or Edcor output iron. And something like the Allied Electronics power transformers and Triad chokes will cut some of the build price.
But a preamplifier, especially a linestage, is a great place to start.
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Again, thank you to everyone that has responded. I do appreciate the help. I'm looking at all the amps that were suggested. Thankfully, they all seem to have parts lists. Getting the parts seems to be a challenge. I can't find one source that has all of the parts. I can't find 120uf 500v capacitors, 1500uf 6.3v capacitors, FRED diodes, 150k 3w resistors, and 10k 3w resistors. Any help would be greatly appreciated.
AGW
AGW
Approximate.
Caps are typically +/- 20% so in range is fine, higher voltage rating is ok. Fast recovery diodes are everywhere - if you can't find them its not a huge tragedy, use Schottkys. 150k resistor needing 3w dissipation rating? Really? Its either dropping a huge voltage or carrying a huge current. Even so, it would be available in 5w or as a pair of 300k 2W devices. Same with the 10k.
Caps are typically +/- 20% so in range is fine, higher voltage rating is ok. Fast recovery diodes are everywhere - if you can't find them its not a huge tragedy, use Schottkys. 150k resistor needing 3w dissipation rating? Really? Its either dropping a huge voltage or carrying a huge current. Even so, it would be available in 5w or as a pair of 300k 2W devices. Same with the 10k.
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A good starting point would be to decide to make this a journey. Start with an experimental chassis where you can safely play with the parts. A low cost letter sized 3" deep metal chassis from Hammond (or larger !), Al for ease of machining. Put some rubber feet on it and get ready to fill it full of holes.
Then invest in the expensive parts, choosing them so that they might serve you even if you make a few design changes along the way. Find as much as you can about the specifications for the Tango transformer and look for something equivalent. It don't have to be the same, the journey will end at your amp not an exact copy of Herbs perhaps.
Then invest in the expensive parts, choosing them so that they might serve you even if you make a few design changes along the way. Find as much as you can about the specifications for the Tango transformer and look for something equivalent. It don't have to be the same, the journey will end at your amp not an exact copy of Herbs perhaps.
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Output transformer:
These guys say they are going to carry on the Tango line, but I'd be very cautious. Could at least try contacting them and telling them what you want.
Another place to approach is Sowter, email them and tell them about your desires and see what they can offer. Ask Lundhal too. Just write them all and tell them 'Flesh and Blood' !
These guys say they are going to carry on the Tango line, but I'd be very cautious. Could at least try contacting them and telling them what you want.
Another place to approach is Sowter, email them and tell them about your desires and see what they can offer. Ask Lundhal too. Just write them all and tell them 'Flesh and Blood' !
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