-Some how it was stuck in my head that it couldn't be done, but I just wanted to clarify. Thanks for clearing that up for me!
- Thanks so much for weighing in! I am going to try to contact James when the time gets closer to try to get a direct quote, I could use some preamp iron from them as well, but if that falls through One Electron is my next "budget" choice. I have cut back costs a bit on a over all design choice, but I still have to price Electra-Prints. I estimate that compared to Hammonds the James are +$30 (direct), One Electron +$60 or so, and Electra's +$200 or so. This is for a pair, the Electra's WAY more costly, but from what I read they are worth every penny. I am leaning more on the One Electron's or James' though because I have to pay for college
, but we will see how the summer goes.I have no idea, would anyone like to weigh in? Interesting tube, I didn't know it was designed to drive the 300B.
I took a trip the other day to my local wood working shop to check out different case woods and to generally look around. I have a few wood selection in mind, I am thinking White Cherry with Al top, Black Walnut with Al or Cu top, maybe Zebra Wood or Olive Wood, they have both of these but only in small quantities. I was also thinking of Teak, I have a couple big pieces of Teak but I haven't decided if I want to cut the monsters up yet. I got some cheap scrap pine to practice my box joints and dovetails over the next few days when I find time. Currently in the process of updating/renovating a rental property with my dad, plus home landscaping, plus my normal job...part time though so it's not so bad. Too much work and not enough play as of late, I don't think it will letting up a for a little either, I guess that is what they call real life though.
I am about 99% decided on a design, I am going to build a 91A style 300B Amplifier. I have slowly been reading a little bit, more and more each day, about this amplifier. I may start out triode strapping the pentode though, just from an ease-of-build stand point. Although I guess to use the tube like a real pentode it is only about 3 more parts. Sorry andyjevans, the all DHT I feel is just a slight bit out of my budget for this round. Don't worry though, very soon one (or should I say a pair) will be gracing my listening quarters! You have got my little empty head swimming with DHT dreams, I think I have read more about them in the past weeks than I have ever known. I do believe though that my 26/10Y/71A (one of these three) line amp will get moved up, maybe even built along side the 300B, at least the case will. I was very stuck on the DHT design, I am just worried about the cost of the IT and the tubes I don't have. I will see though as the build progresses, but more than likely no.
My biggest question is what to use as the pentode at the front end. I would really like to use a WE310A, but probably not to start. I have to go through my tubes and check what I have for pentodes. I know I have at least 10 NOS RCA 6J7's that I could put to use. If I bought pentodes these are the choices I am looking at: 12HG7A, D3a, C3g/m, E55L, 11HM7. I am open to any suggestions, feedback, reviews, anything. The biggest plus I with the 6J7 is that I already have a bunch of them, I just am not sure how they compare to some of these other choices. On that note here is the basic layout, in words, I will try to do some paint work, or just take a pic of my hand schematic, don't worry I draw clean schematics
.-Amp: 6J7 (for now) -> R-c coupled -> 300B Ultra-Path
-PSU: 5U4G -> C (small) -L-C-R-C
The little C will be a film or a small oil and all the other caps will be ASC oil's. I have heard good things about these caps, they will probably be used in as the Ultra-Path cap as well.
I am still keeping DRD in my head, it will need a little bit different of a PSU, but the reviews I have heard of it are to good for me not to consider it. This this design though I feel it is easy to build a 91A style amp, then try triode strapping the driver, then with a few tweaks try DRD. Maybe in the future with very few changes swap the front end, modify, and try SRPP. Or maybe modify and try 417A and IT or all DHT when money permits. I assume too that it would be no problem to add in an IT at a later date, triode strap the driver, and have a 417A+IT style amp. I just feel that the cost to implement this amp will be about the same as with the 6SN7 JE Labs, but it seems to be a better design. On paper it seems it will more adequately drive the 300B full swing with much lower distortion than the 6SN7. A lot of people seem to like the sound of this style amp too, and to me that is more of a plus than measurements
Thanks to all that have contributed, I didn't dream of getting this much feedback! I am still open to any suggestions or comments!
Cheers
James
edit: Does anyone know much about the Western Electric Output mentioned by Lynn Olson in his ETF presentation? Even better has anyone tried it to see how it sounds? Would it still give me the same 8watts or so output power? To me it seems to be similar to the Ultra-Path, but a bit better because it keeps a couple more parts out of the "input loop".
edit #2: What do I have to consider (or can I at all) to direct couple instead of R-C couple the input and output? Has anyone L-C coupled a 91A type amp? I guess I have an unnatural lust for choke loaded tubes, maybe I should see someone, I don't know what they would say when I said I like choking tubes...especially triodes
!
JPeitzman said:
Good idea ! 6J7 is the best : avoid these hi gm toobz as input. Don't try 6SJ7 : theyre are not subs
I'll have to go in a WE231D /71A / 50 in the next months for a monaural Altec 604 : i have only the tubes and xformers for a single unit and don't want to spend bucks there for a brother James, if you are researching the 91's, make sure you read Joe Roberts SP article (if you haven't already). The 91's and various clones acheived a cult like status in France a few years ago, so there seems to be plenty of articles and schematics floating around. The variant I built used some of T Loesh's ideas, although I opted for a much simpler power supply, and I used separate cathode resistors and bypass caps on each leg of the filament, along with a separate WE bypass cap on each leg of the filament. I chose to use lclc dc on 300b filaments. There is a nice synergy between the pentode driver and the triode output.
jim
jim
Check out the Silk transformers. Very well built and great sound at a reasonable cost. www.sacthailand.com
Very well built and great sound at a reasonable cost
Dear Andy,
Can you tell me which "sound" experience you have with these Silk transformers. Did you built a 300B amp with these "Silks"yourself and did you use the interstage of Silk I use the IT Tango NC 20 but this transformer is really expensive and I want to built a second 300B amp.
Regards
Jos
Dear Andy,
Can you tell me which "sound" experience you have with these Silk transformers. Did you built a 300B amp with these "Silks"yourself and did you use the interstage of Silk I use the IT Tango NC 20 but this transformer is really expensive and I want to built a second 300B amp.
Regards
Jos
A friend had his little 6W EL 34 single ended amp which sounded suprisingly good. Very good bass and smooth highs. Decent amp design but cheaped out on the power supply a bit by not using a choke. I have talked to other people who have used Silk transformers and are very happy with the results.
The old saying is true, your tube amp is only as good as the output transformer. Which goes double for single ended. I am a big fan of the Electra Print iron. Plus Jack can be a wealth of info if you ask pertinent questions. The Silks seem to be as good as any of the better quality transformers at a bit better price. The Magnaquest 3k single ended output are very nice but pricey. I am not much of a Hammond fan for outputs but Hammonds work well enough for power supplies. Many years ago I built a W.E. 91 clone with 6SJ7 input. I got the schematic from Angela Instruments. I built them with Hammonds for outputs which sounded O.K. But was surprised at how much better the Magnaquest 3k outputs sounded. I've built several amps using interstage transformers from Electra Print both for single end and push pull and the sound was fabulous. I am a big fan of Jack's DRD amps. I've built 4-5 pairs for friends and all are very pleased with the amps.
The old saying is true, your tube amp is only as good as the output transformer. Which goes double for single ended. I am a big fan of the Electra Print iron. Plus Jack can be a wealth of info if you ask pertinent questions. The Silks seem to be as good as any of the better quality transformers at a bit better price. The Magnaquest 3k single ended output are very nice but pricey. I am not much of a Hammond fan for outputs but Hammonds work well enough for power supplies. Many years ago I built a W.E. 91 clone with 6SJ7 input. I got the schematic from Angela Instruments. I built them with Hammonds for outputs which sounded O.K. But was surprised at how much better the Magnaquest 3k outputs sounded. I've built several amps using interstage transformers from Electra Print both for single end and push pull and the sound was fabulous. I am a big fan of Jack's DRD amps. I've built 4-5 pairs for friends and all are very pleased with the amps.
How would you say the Silks sound compared to the Electra's? I have heard very good things about the Electra's and the Silks seem to be prices similar to me. I am glad to hear too that you have used their interstage transformers, when the time comes in the future I think Electra's will be my interstage choice.
How would you say the DRD design compares to the 91A design?
Cheers
James
How would you say the DRD design compares to the 91A design?
Cheers
James
James,
I've been bouncing around a 300B build as well but you seem to have gone a bit further than I. I've got bits and pieces that I've purchased that are not tube dependent but am still searching for a design. Ive looked at the Walton design you first posted, Derek is a great guy and answers questions quite fast. As I've not decided I still have flexibility . Anyway, care to post a link to the design you are going to use?
Thanks
I've been bouncing around a 300B build as well but you seem to have gone a bit further than I. I've got bits and pieces that I've purchased that are not tube dependent but am still searching for a design. Ive looked at the Walton design you first posted, Derek is a great guy and answers questions quite fast. As I've not decided I still have flexibility
. Anyway, care to post a link to the design you are going to use?Thanks
^^^
Well, maybe a bit further, but I too am in the "bouncing around" stage, just the later stage. I have decided that I want to see what this whole SET and 300B buzz is all about. As far as a design I think I am going to do the classic WE 91A style amplifier. I too am still being quite flexible, I have been reading more and more about DRD's and they are still a very attractive option, along with transformer driven DHT's or IDHT's. Personally I like the idea of a single pentode driving the output, and I hear good things about this driver arrangement. I also like the flexibility of the pentode driver with it's ability to be converted to a triode with just a few simple connections. The only thing I am slowly starting to dislike about the 91A design is the fact that it is a bit more complicated than the IT coupled or DRD designs. So it seems after about a week of being about 100% I may be switching my decision again. I am keeping all DHT's stuck in the back of my mind!
http://www.timebanditaudio.com/300b/WE91A.pdf
http://www.audiodesignguide.com/my/se1.html
http://electra-fidelity.com/300B6AN4amp.aspx
There is a much larger and updated version of the DRD 300B (the last one) if you go to Electra-Prints website and go under schematics. As for the all DHT 26 -> 10Y -> 300B, I don't have a link for this one, it is all on paper and in my head...though not MY design. If you search around you can find info on all DHT amps, 300B or otherwise. As for my design, right now I am leaning harder on the first one, the 91A design. Although my final design is subject to change without notice! I am going to build the chassis, the power supply, and the output suction which will not change much, after that point I may build a few different front ends depending on money and see which one sound the best to my ears.
My question to the experts: Between the DRD design and the IT coupled design like the second link, which would be best, or is it kind of a toss up?
Cheers
James
BTW: Does anyone know much about these?
http://www.vt4c.com/shop/program/main.php?cat_id=55&group_id=7&hit_cat=
Good transformers at all for line stages, front ends, or testing? To me they seem dirt cheap and slim enough to fit under or inside a chassis to be used to power a front end. For testing I was drawn to the first part, dirt cheap. Although it is $20-$60 I don't want to be taken so I was wanting some opinions, thanks!
Well, maybe a bit further, but I too am in the "bouncing around" stage, just the later stage. I have decided that I want to see what this whole SET and 300B buzz is all about. As far as a design I think I am going to do the classic WE 91A style amplifier. I too am still being quite flexible, I have been reading more and more about DRD's and they are still a very attractive option, along with transformer driven DHT's or IDHT's. Personally I like the idea of a single pentode driving the output, and I hear good things about this driver arrangement. I also like the flexibility of the pentode driver with it's ability to be converted to a triode with just a few simple connections. The only thing I am slowly starting to dislike about the 91A design is the fact that it is a bit more complicated than the IT coupled or DRD designs. So it seems after about a week of being about 100% I may be switching my decision again. I am keeping all DHT's stuck in the back of my mind!
http://www.timebanditaudio.com/300b/WE91A.pdf
http://www.audiodesignguide.com/my/se1.html
http://electra-fidelity.com/300B6AN4amp.aspx
There is a much larger and updated version of the DRD 300B (the last one) if you go to Electra-Prints website and go under schematics. As for the all DHT 26 -> 10Y -> 300B, I don't have a link for this one, it is all on paper and in my head...though not MY design. If you search around you can find info on all DHT amps, 300B or otherwise. As for my design, right now I am leaning harder on the first one, the 91A design. Although my final design is subject to change without notice! I am going to build the chassis, the power supply, and the output suction which will not change much, after that point I may build a few different front ends depending on money and see which one sound the best to my ears.
My question to the experts: Between the DRD design and the IT coupled design like the second link, which would be best, or is it kind of a toss up?
Cheers
James
BTW: Does anyone know much about these?
http://www.vt4c.com/shop/program/main.php?cat_id=55&group_id=7&hit_cat=
Good transformers at all for line stages, front ends, or testing? To me they seem dirt cheap and slim enough to fit under or inside a chassis to be used to power a front end. For testing I was drawn to the first part, dirt cheap. Although it is $20-$60 I don't want to be taken so I was wanting some opinions, thanks!
James,
On the trannies, at least my read granted I am tired and about to hit the sack BUT I am reading this as custom trannies are only available if ordering 50+ items. Not sure I read them correctly but...
I am getting my power trannies from Boris at Altavista engineering audio@engineeringvista.com. I have had good luck with their toroid power trannies and have priced a power toroid tranny with 5 secondaries for $80 each.
I am settling on this design but changing it for me:
http://homepage.mac.com/parisatnight/hobby/PhotoAlbum2.html
I am changing the 6J5 for 7193 and see how it works. I am also looking at changing some of the cap values, nothing elaborate.
Thank you for sharing your version of the disease.
On the trannies, at least my read granted I am tired and about to hit the sack BUT I am reading this as custom trannies are only available if ordering 50+ items. Not sure I read them correctly but...
I am getting my power trannies from Boris at Altavista engineering audio@engineeringvista.com. I have had good luck with their toroid power trannies and have priced a power toroid tranny with 5 secondaries for $80 each.
I am settling on this design but changing it for me:
http://homepage.mac.com/parisatnight/hobby/PhotoAlbum2.html
I am changing the 6J5 for 7193 and see how it works. I am also looking at changing some of the cap values, nothing elaborate.
Thank you for sharing your version of the disease.
That is the original schematic I was looking at and that amp is the inspiration behind the chassis for my build. I haven't been able to move forward as of yet with the chassis because most of my tools are in use. I spent the better part of today doing some finishing carpentry (trim work and molding) at one of our rental properties. As soon as all the work is done there I will be able to get started. Unfortunately I don't really have a choice in the matter, I want to get started but the rentals pay the bills so that comes first.
The only problem I saw with that schematic is the use of the 6J5, essentially ½ of a 6SN7. This arrangement can in fact drive a 300B but not as good as other drivers and at higher THD. After reading about different driver arrangements it seems the main advantages to the 6SN7 (or in this case 2 x 6J5) are the ease of implementation, tube rolling ease, and the appeal to unversed tube-o'-philes of the popular 300B being paired with the classic and popular 6SN7. That is why right at beginning of this thread it was brought up that the 6SN7 style arrangement may need something like a MOSFET follower, something like what TubeLab uses. I still am interested to see how this arrangement sounds compared to a DRD, all DHT, IT 417A, or 91A. Especially with choke loading, this should allow the driver to swing more voltage into the 300B, yet I don't think it will be the same as a better driver.
I think though if you decide to pursue this route you will end up happy regardless. Are there any advantages to the 7193 over just a 6J5? It is basically a CV6 which is basically a 6J5 with grid and plate caps, no? Regardless it would look pretty cool with one or two 7193's sitting there, I know I for one am drawn to 1. strange tubes and 2. tubes with caps or multiple caps. If drive and THD become an issue I am sure you could pop out the 6J5 driver, rewire a bit, and pop in a triode strapped 6V6 or something of the sort. This should be like driving it with something like 4 6J5's in parallel. Of course I am sure if you go this route you could drop the input tube since the driver would be more than enough. Check this out, it was posted earlier in this thread:
http://www.pmillett.com/pentodes.htm
Of course a 7193 -> 6V6 Triode (maybe choke loaded ) -> 300B would drive the "little" 300B into the stratosphere, you could probably drive a 211/845/GM70 with this arrangement...hmmm I got myself thinking . See the problem with me is instead of blindly building and being happy I got to reading, searching, and ultimately asking questions here at DIYAudio. Now my head is swimming with ideas and confusion, I have learned over the past few weeks that I know less than I thought I knew...which was not much to start with .
Anyways, I have done some more searching, reading, thinking, a very dangerous combination by the way. I stumbled onto Lundahl's website, a transformer company that I never really thought to consider. After doing to reading and comparing with their interstage transformers and anode chokes I am happy to say that the all DHT design is back on the table! I wanted to try to build the cases roughly the same as the ones from the link posted by 77seriesIII, but I was worried about chassis space with the thin sides and filled up top. I have figured though that I can use Lundahl interstage transformers and chokes and attach them to the side of the chassis on the inside as long as they don't protrude to much into the case. If I do this I will only have to make the sides about 2.25" to 2.5" tall and still have room for everything. I have read so much about all DHT amps and have heard so much good from andyjevans that I felt bad abandoning this design, but now there is still hope!
To andyjevans, or anyone else who would care to comment on the all DHT design, a few quick questions:
1. I know I had asked this before, but is the 26 -> VT-25 -> 300B a better arrangement than using the 71A in place of the VT-25? I know the 71A is lower gain, but from what I hear it is a magical little tube.
2. Are there any other DHT's I should be considering or could consider? I have a pair of WE 264B's, I am yet to test them but if they are good could they be used in this design...input maybe?
3. I am looking at using the LL1677 for the interstage transformer, are there others from Lundahl that I should consider instead?
4. I was thinking of using the LL1667 at the input if I choke load now or in the future, a good choice? Also what do I have to consider if I want to choke load and direct couple the input stage to the driver? The goal on this design if picked would be to have few if any passives in the signal path.
To the USA builders out there that have used Lundahl iron, did you order directly from them or though K&K Audio? K&K is the only one they list under distributors. Thanks for any information and thanks to all that have helped, posted, and maybe even been helped.
Cheers
James
The only problem I saw with that schematic is the use of the 6J5, essentially ½ of a 6SN7. This arrangement can in fact drive a 300B but not as good as other drivers and at higher THD. After reading about different driver arrangements it seems the main advantages to the 6SN7 (or in this case 2 x 6J5) are the ease of implementation, tube rolling ease, and the appeal to unversed tube-o'-philes of the popular 300B being paired with the classic and popular 6SN7. That is why right at beginning of this thread it was brought up that the 6SN7 style arrangement may need something like a MOSFET follower, something like what TubeLab uses. I still am interested to see how this arrangement sounds compared to a DRD, all DHT, IT 417A, or 91A. Especially with choke loading, this should allow the driver to swing more voltage into the 300B, yet I don't think it will be the same as a better driver.
I think though if you decide to pursue this route you will end up happy regardless. Are there any advantages to the 7193 over just a 6J5? It is basically a CV6 which is basically a 6J5 with grid and plate caps, no? Regardless it would look pretty cool with one or two 7193's sitting there, I know I for one am drawn to 1. strange tubes and 2. tubes with caps or multiple caps. If drive and THD become an issue I am sure you could pop out the 6J5 driver, rewire a bit, and pop in a triode strapped 6V6 or something of the sort. This should be like driving it with something like 4 6J5's in parallel. Of course I am sure if you go this route you could drop the input tube since the driver would be more than enough. Check this out, it was posted earlier in this thread:
http://www.pmillett.com/pentodes.htm
Of course a 7193 -> 6V6 Triode (maybe choke loaded
) -> 300B would drive the "little" 300B into the stratosphere, you could probably drive a 211/845/GM70 with this arrangement...hmmm I got myself thinking . See the problem with me is instead of blindly building and being happy I got to reading, searching, and ultimately asking questions here at DIYAudio. Now my head is swimming with ideas and confusion, I have learned over the past few weeks that I know less than I thought I knew...which was not much to start with .Anyways, I have done some more searching, reading, thinking, a very dangerous combination by the way. I stumbled onto Lundahl's website, a transformer company that I never really thought to consider. After doing to reading and comparing with their interstage transformers and anode chokes I am happy to say that the all DHT design is back on the table! I wanted to try to build the cases roughly the same as the ones from the link posted by 77seriesIII, but I was worried about chassis space with the thin sides and filled up top. I have figured though that I can use Lundahl interstage transformers and chokes and attach them to the side of the chassis on the inside as long as they don't protrude to much into the case. If I do this I will only have to make the sides about 2.25" to 2.5" tall and still have room for everything. I have read so much about all DHT amps and have heard so much good from andyjevans that I felt bad abandoning this design, but now there is still hope!
To andyjevans, or anyone else who would care to comment on the all DHT design, a few quick questions:
1. I know I had asked this before, but is the 26 -> VT-25 -> 300B a better arrangement than using the 71A in place of the VT-25? I know the 71A is lower gain, but from what I hear it is a magical little tube.
2. Are there any other DHT's I should be considering or could consider? I have a pair of WE 264B's, I am yet to test them but if they are good could they be used in this design...input maybe?
3. I am looking at using the LL1677 for the interstage transformer, are there others from Lundahl that I should consider instead?
4. I was thinking of using the LL1667 at the input if I choke load now or in the future, a good choice? Also what do I have to consider if I want to choke load and direct couple the input stage to the driver? The goal on this design if picked would be to have few if any passives in the signal path.
To the USA builders out there that have used Lundahl iron, did you order directly from them or though K&K Audio? K&K is the only one they list under distributors. Thanks for any information and thanks to all that have helped, posted, and maybe even been helped.
Cheers
James
Thanks for the boost of confidence for K&K!
I had mentioned before that I was thinking of using the LL1667 to load the 26/10Y/whatever gets used at the input stage. For about $10-$15 more I could just use another interstage, is this a better choice? That would be 26 IT coupled to a 10Y or 71A IT coupled to the 300B. That would take care of basically almost all passives in the signal path and the Ultra-Path output would help even more. For those that have tried is the any differences between choke loaded and IT coupled? I am assuming that they are more or less one in the same.
Thanks for the help!
Cheers
James
I had mentioned before that I was thinking of using the LL1667 to load the 26/10Y/whatever gets used at the input stage. For about $10-$15 more I could just use another interstage, is this a better choice? That would be 26 IT coupled to a 10Y or 71A IT coupled to the 300B. That would take care of basically almost all passives in the signal path and the Ultra-Path output would help even more. For those that have tried is the any differences between choke loaded and IT coupled? I am assuming that they are more or less one in the same.
Thanks for the help!
Cheers
James
I have a few questions unrelated to the 300B build and I didn't want to start a brand new thread. I also have a few updates to the 300B as well as questions on it as well.
First the unrelated questions:
1. Has anyone done much work with the Janus Shunt Regulator outlined on Tubcad? I am planing on using it to get a regulated 250v out after a C-L-C filter for a line stage (12B4A / test platform for others). I was thinking of using a 12HG7 for the first tube and ½ 6080 for the triode half (This is the pentode driven Janus, but the 12HG7 can be triode wired as well). I am using the 6080 because each channel will have it's own regulator(so one 6080 plus two 12HG7's). I am just wondering if there are any better choices for regulators. I am also wondering if the 6080 will be pushed to hard since 250v I believe is right at it's max. They cost about as much as a 6-pack but I would prefer not to kill them every couple months. I am also having some trouble with calculating the values, can someone help point me in the right direction. I don't want someone to do it for me, I want to learn with a little support there just in case. Any other tubes, I am open to suggestions! I was using these tubes because they give me tons of head room no matter what line stage I drop in.
2. Has anyone ever played with the 7241 or 7242? They are huge power triodes made for pass applications in regulators. They can take medium voltage (400v max) but high current. They have low plate resistance, low mu, 100watt max dissipation, and crazy high transconductance. They seem like they could make good SET amps maybe in the same class as the GM70 and 845, I don't know where to find them though, and they might sound
, very interested though.
3. Has anyone ever used the 7233 as a line stage? I am thinking about picking up a few of these to try with a few mods in the 12B4A line amp.
4. Can the 12B4A or the like (low mu line amps) benefit at all from a White-Cathode Follower at their output? If so I don't know what tube to use, 6922(?), 5687(?)....?
5. How does the 5Y3 sound? I have a few I was thinking of using for line amp projects, saving my 5R's,5AR's, and 5U's for power amps.
Now the related questions and comments:
There has been a slight change in iron due to a change in the chassis design. I am going to try to build a chassis similar to the one used on the Musical Machine (AudioTropic). I am building a few small ones for line amps and a couple big ones for the amps. This tightens things a bit on the power supply side (space wise) but opens things up a bit on the amplifier side. Because of this I am now planing on using Electra-Print interstage transformers and anode chokes. This actually lowers the cost from when I was planing on Lundahl iron by about $60 per channel.
I guess my main question now is what is the better tube choice. I know andy talked quite a bit about this, I am still interested though.
-26 input , 10Y driver
-26 input , 71A driver
-10Y input , 10Y driver
-10Y input , 71a driver
Can the 10Y run ok at volts near that of the 71A and 26? Also can the 264B be used at the input or are the above better choices. I am still considering too the 417A or a very high transconductance triode or triode wired pentode through an interstage, a better choice than all DHT? The more I have read about transformer coupled amps, along with the few recent changes to design, the more I feel it is the best choice. It seems that I mostly hear that they are detailed and dynamic, which is part of what I am looking for.
Thanks in advance, also would like to apologize in advance to the mods for bringing my own thread off topic. If the top OT questions warrant their own thread feel free. I just didn't want to clutter things up with a new thread.
Cheers
JD
First the unrelated questions:
1. Has anyone done much work with the Janus Shunt Regulator outlined on Tubcad? I am planing on using it to get a regulated 250v out after a C-L-C filter for a line stage (12B4A / test platform for others). I was thinking of using a 12HG7 for the first tube and ½ 6080 for the triode half (This is the pentode driven Janus, but the 12HG7 can be triode wired as well). I am using the 6080 because each channel will have it's own regulator(so one 6080 plus two 12HG7's). I am just wondering if there are any better choices for regulators. I am also wondering if the 6080 will be pushed to hard since 250v I believe is right at it's max. They cost about as much as a 6-pack but I would prefer not to kill them every couple months. I am also having some trouble with calculating the values, can someone help point me in the right direction. I don't want someone to do it for me, I want to learn with a little support there just in case. Any other tubes, I am open to suggestions! I was using these tubes because they give me tons of head room no matter what line stage I drop in.
2. Has anyone ever played with the 7241 or 7242? They are huge power triodes made for pass applications in regulators. They can take medium voltage (400v max) but high current. They have low plate resistance, low mu, 100watt max dissipation, and crazy high transconductance. They seem like they could make good SET amps maybe in the same class as the GM70 and 845, I don't know where to find them though, and they might sound
, very interested though. 3. Has anyone ever used the 7233 as a line stage? I am thinking about picking up a few of these to try with a few mods in the 12B4A line amp.
4. Can the 12B4A or the like (low mu line amps) benefit at all from a White-Cathode Follower at their output? If so I don't know what tube to use, 6922(?), 5687(?)....?
5. How does the 5Y3 sound? I have a few I was thinking of using for line amp projects, saving my 5R's,5AR's, and 5U's for power amps.
Now the related questions and comments:
There has been a slight change in iron due to a change in the chassis design. I am going to try to build a chassis similar to the one used on the Musical Machine (AudioTropic). I am building a few small ones for line amps and a couple big ones for the amps. This tightens things a bit on the power supply side (space wise) but opens things up a bit on the amplifier side. Because of this I am now planing on using Electra-Print interstage transformers and anode chokes. This actually lowers the cost from when I was planing on Lundahl iron by about $60 per channel.
I guess my main question now is what is the better tube choice. I know andy talked quite a bit about this, I am still interested though.
-26 input , 10Y driver
-26 input , 71A driver
-10Y input , 10Y driver
-10Y input , 71a driver
Can the 10Y run ok at volts near that of the 71A and 26? Also can the 264B be used at the input or are the above better choices. I am still considering too the 417A or a very high transconductance triode or triode wired pentode through an interstage, a better choice than all DHT? The more I have read about transformer coupled amps, along with the few recent changes to design, the more I feel it is the best choice. It seems that I mostly hear that they are detailed and dynamic, which is part of what I am looking for.
Thanks in advance, also would like to apologize in advance to the mods for bringing my own thread off topic. If the top OT questions warrant their own thread feel free. I just didn't want to clutter things up with a new thread.
Cheers
JD
James,
The question is what kind of input sensitivity do you need?
Most 6SN7 input/driver stages will give you very low (say .3V to .7V) input sensitivity.
Are you using a preamp? If you are, you don’t need that low level of input sensitivity.
My current amp was a WE91Clone…. I was happy with it until I got a scope and got to measure things like distortion. I ended up converting the pentode to “triode mode”… that changed the input sensitivity from .5V to about 2V, but the distortion went way down.
So based on my experience with distortion, I would not recommend a WE91 Clone.
Here are two things I have learned searching for the input/drivers for a 300B
1. select the input tube for the level of input sensitivity you need
2. select a driver that will pass at least 10ma
This more than likely means 2 tubes…..
BTW, I would recommend Iron from Electra Print…
The question is what kind of input sensitivity do you need?
Most 6SN7 input/driver stages will give you very low (say .3V to .7V) input sensitivity.
Are you using a preamp? If you are, you don’t need that low level of input sensitivity.
My current amp was a WE91Clone…. I was happy with it until I got a scope and got to measure things like distortion. I ended up converting the pentode to “triode mode”… that changed the input sensitivity from .5V to about 2V, but the distortion went way down.
So based on my experience with distortion, I would not recommend a WE91 Clone.
Here are two things I have learned searching for the input/drivers for a 300B
1. select the input tube for the level of input sensitivity you need
2. select a driver that will pass at least 10ma
This more than likely means 2 tubes…..
BTW, I would recommend Iron from Electra Print…
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