hmm. Definitely interested then in the 7193 > 6v6 > 300B then, kt88s would be an interesting look though... Where could I find more information on what would have to change from the schematic (id'ed earlier) to fit the 6v6 in? You mention a choke or css as a possibility and I do not have enough knowledge to figure out which would be better or where to place them in the circuit. Could you possibly point me in the direction where I could find the information? I wouldnt mind if you told me the how and where but I still want to know the why before implementation, just the way I am. I found some coke bottle 6v6s on epray and may give them a whirl if it makes sense and based on your excitement it seems that it will.
/e
/e
I tried this back when my amp was a WE91 Clone, but I decided to to use the 0C3's because
1. I could not hear any difference with / without
2. You "Burn" 15-20ma to make them work correctly
3. I decided to stay closer to the original we91 circuit
Also, you might find this site usefull for we91 type amps
http://www.timebanditaudio.com/timebandit.html
I was a little confused at first, but I figured that was what you meant, thanks!
I have a few questions regarding the 91A design, namely the one that is shown in Sound Practices by Joe Roberts. I think I am going to build this one pretty much as is with a couple changes to the power supply. It will be as follows:
380-0-380 -> RCA 5U4G -> 4uF or there about -> 10H -> 2x50uF -> 25k aluminum housed wire wound -> 2x20uF
I was planning on keeping the 50k to ground (R1 in the schematic) as well. The B+ (for the 300B and feeding the 75k (R8) to the screen grid) will come off the 50uF's and the C+ (feeding the 91k (R9) to the 6J7 plate) will come off the 20uF's. This increases the supply capacitance substantially over what is called for in the Sound Practices article.
One question I had though is do I have to DC bias the heater on the 6J7/6C6/310A as is shown? Not a big deal if I have to I am just wondering what advantage it brings or if it is needed.
Another question is how critical are the values of the cathode bypass capacitors in both the 6J7 and the 300B? I am planing on sticking to the design to start, but I was wondering for in the future. I think I am going to start with some "cheap" SCR Films from Angela in these positions then upgrade to ASC Oil Caps in the future. I am going to leave space on the case to later drill the holes.
Was also interested if Ultra-Path was a good idea to consider on this design? I know I have talked a lot about it in the past but was hoping to hear from some experts on this subject. I am just guessing but if I do go with Ultra-Path is 70uF about the right value...how to I calculate this? This again is one of those things that I think would be done in the future.
Other than that I am planing on using One Electron iron in the output, Hammond iron on the power supply side...or maybe the Angela Universal. I am planing ASC Oils in the power supply along with Arcol aluminum housed wire wounds. On the power amp side I am planing on using SCR's from Angela for coupling and bypass caps to start and switch to ASC's later. I am looking for high power resistors namely 75k, 30k, and 880R. I considered the RCD Non-Inductive 50watt from Angela for the 880R, I am just trying to compare prices for this position. Has anyone ever used high power Thick Films from Caddock in this position? I know in solid state gear the Caddocks have made a very good name for their sound qualities. For the other resistors I was planning on using Kiwame's though I may pick up some 2 watt Allen Bradly's to see how they sound. Eventually I may try some tant's or Riken's, but not right away. Has anyone used any of the new carbon comps from Mouser or Digikey? I am wondering how they sound compared to the old stuff (AB's and IRC's) and the pricey boutique parts like Riken. Mills doesn't seem to have the 75k and 30k unless they are 12watts which are really not needed. I can get Vishay RS series wire wounds if people thing they would work OK.
Slowly but surely this build will get off the ground, though it may extend past summer. The cases will be built soon and populated by passives. I am still planing on using wood unless I can find a cheap local source for fairly thick aluminum...which I kind of have to anyways for some other projects. I think along with the passives will come the 300B's, the only tubes I don't readily have. I think the iron will come in batches the outputs and then the iron for the power supplies. My girlfriend wasn't exactly thrilled at the price of the build but after seeing what retail is for 300B amps I think it has smoothed over. Besides I am hoping that these will be reference and have a home in my system for a long time.
The only thing that is really eating into the amp budget is my love of hiking/climbing. I have to opportunity to get out more this summer, and with the possibility of a summit-bagging weekend or longer looming I felt it was time for a little bit of a gear overhaul. Sorry but climbing is my first passion, audio and biking in a tie for second with friends + good beer/wine right behind. I guess for a 21 year old climber I have somewhat refined tastes. For those who don't know when I say summit-bagging it is when you hit multiple mountain summits in one round, or one or two a day over a few days. I have a goal and check list to hit every 14,000ft.+ mountain in Colorado then move to the US, then bigger mountains await. A Kilimanjaro summit trip is in the planing stages and I plan on using it as a launch to the rest of the "7 Summits". For some reason I have a passion for Kilimanjaro, that is why I want to start with it instead of Mckinley which would be easier since it is state-side.
Anyways that is enough boring you with my non-audio life. Thanks for all the help and input on this subject!
Cheers
James
I have a few questions regarding the 91A design, namely the one that is shown in Sound Practices by Joe Roberts. I think I am going to build this one pretty much as is with a couple changes to the power supply. It will be as follows:
380-0-380 -> RCA 5U4G -> 4uF or there about -> 10H -> 2x50uF -> 25k aluminum housed wire wound -> 2x20uF
I was planning on keeping the 50k to ground (R1 in the schematic) as well. The B+ (for the 300B and feeding the 75k (R8) to the screen grid) will come off the 50uF's and the C+ (feeding the 91k (R9) to the 6J7 plate) will come off the 20uF's. This increases the supply capacitance substantially over what is called for in the Sound Practices article.
One question I had though is do I have to DC bias the heater on the 6J7/6C6/310A as is shown? Not a big deal if I have to I am just wondering what advantage it brings or if it is needed.
Another question is how critical are the values of the cathode bypass capacitors in both the 6J7 and the 300B? I am planing on sticking to the design to start, but I was wondering for in the future. I think I am going to start with some "cheap" SCR Films from Angela in these positions then upgrade to ASC Oil Caps in the future. I am going to leave space on the case to later drill the holes.
Was also interested if Ultra-Path was a good idea to consider on this design? I know I have talked a lot about it in the past but was hoping to hear from some experts on this subject. I am just guessing but if I do go with Ultra-Path is 70uF about the right value...how to I calculate this? This again is one of those things that I think would be done in the future.
Other than that I am planing on using One Electron iron in the output, Hammond iron on the power supply side...or maybe the Angela Universal. I am planing ASC Oils in the power supply along with Arcol aluminum housed wire wounds. On the power amp side I am planing on using SCR's from Angela for coupling and bypass caps to start and switch to ASC's later. I am looking for high power resistors namely 75k, 30k, and 880R. I considered the RCD Non-Inductive 50watt from Angela for the 880R, I am just trying to compare prices for this position. Has anyone ever used high power Thick Films from Caddock in this position? I know in solid state gear the Caddocks have made a very good name for their sound qualities. For the other resistors I was planning on using Kiwame's though I may pick up some 2 watt Allen Bradly's to see how they sound. Eventually I may try some tant's or Riken's, but not right away. Has anyone used any of the new carbon comps from Mouser or Digikey? I am wondering how they sound compared to the old stuff (AB's and IRC's) and the pricey boutique parts like Riken. Mills doesn't seem to have the 75k and 30k unless they are 12watts which are really not needed. I can get Vishay RS series wire wounds if people thing they would work OK.
Slowly but surely this build will get off the ground, though it may extend past summer. The cases will be built soon and populated by passives. I am still planing on using wood unless I can find a cheap local source for fairly thick aluminum...which I kind of have to anyways for some other projects. I think along with the passives will come the 300B's, the only tubes I don't readily have. I think the iron will come in batches the outputs and then the iron for the power supplies. My girlfriend wasn't exactly thrilled at the price of the build but after seeing what retail is for 300B amps I think it has smoothed over. Besides I am hoping that these will be reference and have a home in my system for a long time.
The only thing that is really eating into the amp budget is my love of hiking/climbing. I have to opportunity to get out more this summer, and with the possibility of a summit-bagging weekend or longer looming I felt it was time for a little bit of a gear overhaul. Sorry but climbing is my first passion, audio and biking in a tie for second with friends + good beer/wine right behind. I guess for a 21 year old climber I have somewhat refined tastes. For those who don't know when I say summit-bagging it is when you hit multiple mountain summits in one round, or one or two a day over a few days. I have a goal and check list to hit every 14,000ft.+ mountain in Colorado then move to the US, then bigger mountains await. A Kilimanjaro summit trip is in the planing stages and I plan on using it as a launch to the rest of the "7 Summits". For some reason I have a passion for Kilimanjaro, that is why I want to start with it instead of Mckinley which would be easier since it is state-side.
Anyways that is enough boring you with my non-audio life. Thanks for all the help and input on this subject!
Cheers
James
James, I stuided about 8 different WE91 circuits before I built my We91 Clone. I found the values for both the coulping caps all over the map. Try 220uf//2uf for the 6J7 cathode and 47-100uf for the 300B
For the ultra-path it's = 1/4 of the 300B cathode cap
BTW, I have several threads that cover A LOT of the questions your asking... search for the user name sgerus
Not boring at all, James. You should nickname your 300B project Kilimanjaro!!! Monumental as it is, for a one-off build.
Don't forget, this hobby quickly leads to amp-bagging, as it were... I don't doubt that your 300B amp may last a lifetime, but you're likely gonna get fascinated enough to try some other builds down the line.
I'm getting ready to build up my 300B project too - right now I've got a breadboarded 6L6/5881 SE amp, triode/switchable UL, running in my James 6123HS trannies.
While I have to say that I have no other SE xformers to compare them with, the James are impressively open, clear and extended (subjectively, at least). I am very happy with them, I love the flexibility of the many taps options and they appear to be very high quality construction.
The 5881s are drawing about 45mA each at ~400V, yet the James are not even getting warm!!! They are respectably heavy. I got mine from Euphonia. Shipping was quick, too!
There really seems to be some SET magic going on in my system right now!!! I'm getting addicted. There is a realism and clarity combined with a relaxing presentation that the AtmaSphere M60s can't do. I'm running out of juice on some recordings with 4W into 93dB speakers, but inside the envelope it's nirvahhhna...
I don't like the UltraLinear mode much, although it adds power. My bass guitar head runs 6L6/5881s, so I have a bunch around. I want to use 5881s as drivers for the 300Bs, perhaps. I'm looking into it. Right now I'm using a spare preamp as a driver stage!!! (CCS 12AX7 into CCS cathode follower, plenty of gain and drive, maybe not optimal for sonics but the drive is there)
Don't forget, this hobby quickly leads to amp-bagging, as it were... I don't doubt that your 300B amp may last a lifetime, but you're likely gonna get fascinated enough to try some other builds down the line.
I'm getting ready to build up my 300B project too - right now I've got a breadboarded 6L6/5881 SE amp, triode/switchable UL, running in my James 6123HS trannies.
While I have to say that I have no other SE xformers to compare them with, the James are impressively open, clear and extended (subjectively, at least). I am very happy with them, I love the flexibility of the many taps options and they appear to be very high quality construction.
The 5881s are drawing about 45mA each at ~400V, yet the James are not even getting warm!!! They are respectably heavy. I got mine from Euphonia. Shipping was quick, too!
There really seems to be some SET magic going on in my system right now!!! I'm getting addicted. There is a realism and clarity combined with a relaxing presentation that the AtmaSphere M60s can't do. I'm running out of juice on some recordings with 4W into 93dB speakers, but inside the envelope it's nirvahhhna...
I don't like the UltraLinear mode much, although it adds power. My bass guitar head runs 6L6/5881s, so I have a bunch around. I want to use 5881s as drivers for the 300Bs, perhaps. I'm looking into it. Right now I'm using a spare preamp as a driver stage!!! (CCS 12AX7 into CCS cathode follower, plenty of gain and drive, maybe not optimal for sonics but the drive is there)
sgerus - Thanks for the tip, I will do some searching! Now that I feel that I have decided on a design I should do some more specific searching. I really do feel quite bad when I ask a question and someone says that I should have searched. Not my feelings, I just feel like I have wasted someones time with something I could have just as easily learned on my own. Thanks for the tips too on the bypass caps and the ultra-path cap! I am not sure if ultra-path is really needed as much when you use high quality passives, but it can't hurt to take a couple more passives out of the signal path. It will be something I will just have to play with and tune by ear.
Oh and thanks for the advice on the 0C3, I may try it, but then again I may not. If it didn't seem to make much of a difference then I don't know if it would be worth it. If you don't mind me asking since you said "back when my amp was a WE91 Clone", what is your amp now?
Ha, yeah I can see how "amp-bagging" could very quickly become a problem. I have a very long list of amps that I would like to build. I guess my reasoning for the 300B to kick it off was why not start with the best. I would like to do a KT88 SE also that I am currently dubbing a "high technology" SE. Switchable between triode and ultra-linear, FET voltage regulators, huge modern PSU capacitors, FET CCS for the driver tube and maybe even for the KT88, or some sort of auto bias arrangement. I am thinking of trying the 12HG7 as a driver for the KT88, more than likely a bit of overkill with a CCS load, but I want this thing to SWING! Really interested to see how a classic and timeless 300B design from the 30's compares to a "modern" no-holds SE with balls. My guess, just a guess, the 300B wins
.
Even though too I would like the 300B to last a while I am already fantasizing about other builds. Between the KT88, a 807 PP, a GM70, a 6V6 AudioTropic Musical Machine, etc... Besides that I am drooling over a all DHT 300B design as mentioned in this thread. Yes I believe this has turned into a a expensive and time consuming, yet VERY rewarding hobby. I remember the joy I felt when I fired up my first amp, a original JLH. I also remember the look on the faces of my girlfriend and friends when they heard the music for the first time on this amp. Since then I have logged hours on this amp, but sand can only do so much magic, it is time to explore my true passion when it comes to audio, hollow glass .
I have read some good things about the James', thanks for another vote of confidence! I am thinking that if I build the amp in stages I may be able to use James' instead of One Electron's...though I haven't heard anything bad about these either. Though I will have to shop around and compare prices because at Euphoria's price it is getting close to that magic mark where I could spend a few more bucks and get Electra's. I really have an unnatural love for Electra-Print iron. Maybe because I hear nothing but good about them, maybe because I love the retro look, maybe because I read somewhere they smell really yummy when they are new, who knows. One day I will use Electra's in one of my amps, maybe more than one. I would however like to hear James'...well and Magnequest, One Electron's, Hashimoto's, Tango's, Tamura's, Partridge, Tribute, NOS Western Electric...transformer rolling may be a little out of my budget however, maybe stick to tube rolling and amp building.
On your 6L6, you could probably drive it with something like a 12AX7 SRPP, or ½ of a 12AX7 CCS loaded...just saying 12AX7 because that is what you said. That way you could lose the CCS'd CF stage, though I too am a fan of DRIVE, though I also agree, not at the lose of sonics. What are you planing on tackling for a 300B build? The 5881 would drive the crap out of the 300B! Though I think I read somewhere (correct me if I am wrong) that although similar, the KT66 is superior sonics wise. If you want to brute force drive it with a pentode you could just use a high gm one like mentioned earlier. There is a link in this thread to Mr. Millett's site where he does a high gm shoot-out versus the popular 6SN7 cascade and the 6C45. Some of the results are quite impressive using some of these "spuds", most of which cost between $0.70 - $12.00, though some like the D3A my be a bit more.
Again thanks for the input!
Cheers
James
Oh and thanks for the advice on the 0C3, I may try it, but then again I may not. If it didn't seem to make much of a difference then I don't know if it would be worth it. If you don't mind me asking since you said "back when my amp was a WE91 Clone", what is your amp now?
Ha, yeah I can see how "amp-bagging" could very quickly become a problem. I have a very long list of amps that I would like to build. I guess my reasoning for the 300B to kick it off was why not start with the best. I would like to do a KT88 SE also that I am currently dubbing a "high technology" SE. Switchable between triode and ultra-linear, FET voltage regulators, huge modern PSU capacitors, FET CCS for the driver tube and maybe even for the KT88, or some sort of auto bias arrangement. I am thinking of trying the 12HG7 as a driver for the KT88, more than likely a bit of overkill with a CCS load, but I want this thing to SWING! Really interested to see how a classic and timeless 300B design from the 30's compares to a "modern" no-holds SE with balls. My guess, just a guess, the 300B wins
.Even though too I would like the 300B to last a while I am already fantasizing about other builds. Between the KT88, a 807 PP, a GM70, a 6V6 AudioTropic Musical Machine, etc... Besides that I am drooling over a all DHT 300B design as mentioned in this thread. Yes I believe this has turned into a a expensive and time consuming, yet VERY rewarding hobby. I remember the joy I felt when I fired up my first amp, a original JLH. I also remember the look on the faces of my girlfriend and friends when they heard the music for the first time on this amp. Since then I have logged hours on this amp, but sand can only do so much magic, it is time to explore my true passion when it comes to audio, hollow glass
.I have read some good things about the James', thanks for another vote of confidence! I am thinking that if I build the amp in stages I may be able to use James' instead of One Electron's...though I haven't heard anything bad about these either. Though I will have to shop around and compare prices because at Euphoria's price it is getting close to that magic mark where I could spend a few more bucks and get Electra's. I really have an unnatural love for Electra-Print iron. Maybe because I hear nothing but good about them, maybe because I love the retro look, maybe because I read somewhere they smell really yummy when they are new, who knows. One day I will use Electra's in one of my amps, maybe more than one. I would however like to hear James'...well and Magnequest, One Electron's, Hashimoto's, Tango's, Tamura's, Partridge, Tribute, NOS Western Electric...transformer rolling may be a little out of my budget however, maybe stick to tube rolling and amp building.
On your 6L6, you could probably drive it with something like a 12AX7 SRPP, or ½ of a 12AX7 CCS loaded...just saying 12AX7 because that is what you said. That way you could lose the CCS'd CF stage, though I too am a fan of DRIVE, though I also agree, not at the lose of sonics. What are you planing on tackling for a 300B build? The 5881 would drive the crap out of the 300B! Though I think I read somewhere (correct me if I am wrong) that although similar, the KT66 is superior sonics wise. If you want to brute force drive it with a pentode you could just use a high gm one like mentioned earlier. There is a link in this thread to Mr. Millett's site where he does a high gm shoot-out versus the popular 6SN7 cascade and the 6C45. Some of the results are quite impressive using some of these "spuds", most of which cost between $0.70 - $12.00, though some like the D3A my be a bit more.
Again thanks for the input!
Cheers
James
I have the EF37A (6J7) wired as a triode.... see post 60 in this thread and also see:
http://www.diyaudio.com/forums/showthread.php?s=&threadid=109140
James,
>Mills doesn't seem to have the 75k and 30k unless they are 12watts which are really not needed. I can get Vishay RS series wire wounds if people thing they would work OK.
Don't discount the Mills 12W resistors - they really are great sounding resistors... and you don't have to be dissipating 10W to use them. They'll be hot by then, that's near the upper end of the rating. At 5W they already get warm. They may not be the cheapest, but they are worth it IMO.
>Mills doesn't seem to have the 75k and 30k unless they are 12watts which are really not needed. I can get Vishay RS series wire wounds if people thing they would work OK.
Don't discount the Mills 12W resistors - they really are great sounding resistors... and you don't have to be dissipating 10W to use them. They'll be hot by then, that's near the upper end of the rating. At 5W they already get warm. They may not be the cheapest, but they are worth it IMO.
A good rule of thumb is to use a resistor rated at 4 times the actual wattage it is dissipating.
So let’s say your 91K resistor is dropping 175V @2ma, 175*.002= .35W
.35*4= 1.4 Watts…. So yes, use the 2 watt resistor for the plate load.
For the 1.2K (cathode resistor) .5watt should be ok…you do the math
For the 75K and 30K that from the voltage divider for the pentode g2, keep in mind those values are for a 310A pentode…. Your resistor values may vary.
Another way to provide the g2 voltage is to use one resistor from the b++ to the g2, and then a small cap (.47uf) from g2 to the cathode (not to ground)
Thanks for the advice, I will go through and do some quick calculations. I have seen the alternate g2 connection used before, I was kind of interested if I could do that as well. I was kind of wondering too why the g2 resistor comes off of the B+ while the plate comes off of the B++, was thinking I could just recalculate some values and take both off of a B++.
jeff mai - Yes I will be using oil caps in this amp, all in the PSU, and many places if not all places in the audio circuit. A while back I pulled a couple of big ol' oil caps out of some old AC units. They where 10uF GE's in oval cans. Between then and now I picked up a big free bag of rolled foil and paper 2uF caps that I have been using for coupling, mostly at the output of line amps. I don't know who makes them but they look like big Hovland Musicaps, about the size of a C-cell battery, they sound incredible BTW. Then I built the JFET Bride of Zen which calls for a 10uF output cap, which I am sure I could change to a smaller value, but oh well. Rather than use a handful of 2uF I just decided to use my big oil caps...all I can say is WOW, I am hooked on oil! The sound is every bit as detailed as the rolled foil but it has a different presentation. It is much more natural, liquid, almost like you are listening through oil .
As for carbon resistors, I am still wondering if anyone has compared the new ones (as in through Mouser and Digikey) to AB's and/or Riken's? Will the Kiwame's I was looking to get work just as good, or are AB's or Riken's better? I really do hear nothing but good about Riken's, it just 1 and 2 watt Riken's start to get kind of pricey, not like tant's though!
Cheers
James
jeff mai - Yes I will be using oil caps in this amp, all in the PSU, and many places if not all places in the audio circuit. A while back I pulled a couple of big ol' oil caps out of some old AC units. They where 10uF GE's in oval cans. Between then and now I picked up a big free bag of rolled foil and paper 2uF caps that I have been using for coupling, mostly at the output of line amps. I don't know who makes them but they look like big Hovland Musicaps, about the size of a C-cell battery, they sound incredible BTW. Then I built the JFET Bride of Zen which calls for a 10uF output cap, which I am sure I could change to a smaller value, but oh well. Rather than use a handful of 2uF I just decided to use my big oil caps...all I can say is WOW, I am hooked on oil! The sound is every bit as detailed as the rolled foil but it has a different presentation. It is much more natural, liquid, almost like you are listening through oil
. As for carbon resistors, I am still wondering if anyone has compared the new ones (as in through Mouser and Digikey) to AB's and/or Riken's? Will the Kiwame's I was looking to get work just as good, or are AB's or Riken's better? I really do hear nothing but good about Riken's, it just 1 and 2 watt Riken's start to get kind of pricey, not like tant's though!
Cheers
James
Kimmel MUstage driver
Hi James,
If you really want a versatile driver that can do it all. That will drive anything from 45’s to 845’s.Try the Alan Kimmel choke coupled MUstage driver. Here’s a few that in many way’s will out perform a all DHT Driver section. EF86>choke coupled>EL86>interstage>300B, 6SL7>choke coupled>EL86> interstage>300B, and for the really wild one, the Pentode part of 6BM8>choke coupled>7591>interstage >845 or GM70.The last driver stage can take about 950v+and swing over 900v peak to peak.
Hi James,
If you really want a versatile driver that can do it all. That will drive anything from 45’s to 845’s.Try the Alan Kimmel choke coupled MUstage driver. Here’s a few that in many way’s will out perform a all DHT Driver section. EF86>choke coupled>EL86>interstage>300B, 6SL7>choke coupled>EL86> interstage>300B, and for the really wild one, the Pentode part of 6BM8>choke coupled>7591>interstage >845 or GM70.The last driver stage can take about 950v+and swing over 900v peak to peak.
Or do you mean choke coupled as in choke-loaded? I was kind of thinking a design like that but with DHT's for in the future. With the current input and budgetary reasons I think right will go with the 91A. That is not to say though that I am not open to input, I really like keeping my options open, thanks for the input!
On an off note I went bike shopping today and found the one thing that may kill this project, a 2008 Trek 2.1. I test road the 2.1, a 2007 Trek 1600, and a couple Madone's, a 4.5 and a 5.2. The Madone's are dreamy, very buttery smooth and ultra responsive...though a bit on the pricey side...mmmmmm carbon. The 2.1 and the 1600 are very similar, but the 2.1's carbon rear stays making it a bit more comfy. The 2.1 with some Ultegra SL or Dura-Ace shifters and front/rear derailleurs, maybe an upgraded crank... this could be the bike for me for a few years, unless I go nuts and drop a few hundred for a Madone carbon frame set and load it with Dura-Ace parts. BTW for anyone out there looking for a entry road bike: If you are shopping in the $800 - $1000 price range, even though it is a few hundred more, try out the 2.1 from Trek! I feel with the few extra tweaks that come with it that it is a very nice and well worth it upgrade over the 1 Series. I would recommend the 1600 too, some upgraded parts over the 2.1, but missing the carbon rear stays, bonus is since it is a 2007 model you can often find it for a good price! I felt though too that the use of Ultegra parts on the 1600 coupled with the 10speed rear outweigh the carbon stays, unless you want a soft ride for your rear. Well this and my never ending quest for more climbing gear, I am a bit of a gear nut! Plus much of my stuff has been needing an overhaul, still working on a summer trip so... Sorry that is the end of my way off topic!
Cheers
James
On an off note I went bike shopping today and found the one thing that may kill this project, a 2008 Trek 2.1. I test road the 2.1, a 2007 Trek 1600, and a couple Madone's, a 4.5 and a 5.2. The Madone's are dreamy, very buttery smooth and ultra responsive...though a bit on the pricey side...mmmmmm carbon. The 2.1 and the 1600 are very similar, but the 2.1's carbon rear stays making it a bit more comfy. The 2.1 with some Ultegra SL or Dura-Ace shifters and front/rear derailleurs, maybe an upgraded crank... this could be the bike for me for a few years, unless I go nuts and drop a few hundred for a Madone carbon frame set and load it with Dura-Ace parts. BTW for anyone out there looking for a entry road bike: If you are shopping in the $800 - $1000 price range, even though it is a few hundred more, try out the 2.1 from Trek! I feel with the few extra tweaks that come with it that it is a very nice and well worth it upgrade over the 1 Series. I would recommend the 1600 too, some upgraded parts over the 2.1, but missing the carbon rear stays, bonus is since it is a 2007 model you can often find it for a good price! I felt though too that the use of Ultegra parts on the 1600 coupled with the 10speed rear outweigh the carbon stays, unless you want a soft ride for your rear. Well this and my never ending quest for more climbing gear, I am a bit of a gear nut! Plus much of my stuff has been needing an overhaul, still working on a summer trip so... Sorry that is the end of my way off topic!
Cheers
James
77seriesIII - Sorry I just was reading though all the posts on this page and came across your reply.
I would say for the previous listed schematic that you posted there isn't really to much that you would have to change. Tweak the values for the 6J5 input tube since would use a 7193. Other than that the front end would stay almost the same since the 7193 and the 6J5 are similar tubes. As for the 6V6 driver, personally I would triode strap it, though others can pipe in regarding this decision. Obviously you would have to figure the new component values, but other than the the circuit would look the same, it would just be a lot beefier. For the choke you will have to mind the voltage a little bit and make sure it doesn't exceed the tubes max, the choke does not drop as much voltage as the resistor would. The choke or CCS loads the tube different, it presents a more straight load line. The tube will have a gain almost equal to it's mu. A plus too with the design that you mentioned is that you should be able to eliminate the cathode bypass cap in the driver stage, loosing a source for possible distortion. It will allow the tube to swing a lot more voltage, I don't remember how much more, but I think it is closer to the B+ on the tube, or more, I cannot remember, please someone jump in on this. As a small added benefit you get a little better PSRR for that stage. I think in theory you should be able to even better drive the 300B and the choke load should be more dynamic and detailed.
Just tweaking the values though and keeping the 6V6 RC coupled to the 300B would still have more than enough drive. Like I said before...I think... the triode 6V6 is about like 4 or so 6SN7's all together, as long as the circuit is designed right. I would say if you decide to go this route that I would get some help and calculate the resistor/capacitor values then down the road try a choke load. You could also start by trying a choke load with a 150H Hammond choke, they are about $18.00 or so, much cheaper than Llundahl's, James' etc... Though Electra-Print anode chokes are only about $50 average each.
You can find some information by searching around, and will probably find people much more versed in the use of such devices than I am, I am just a supporter for now. As for CCS's they are similar to chokes but I know much less about them, that is why I didn't touch on them. There are some here though that are very versed in the use of CCS's both as anode loads and cathode loads. I think your design would look awesome with some ST "coke bottle" 6V6's, I bet it would sound good too. I hope this may have answered some questions, or maybe I just made more questions for you, if so, sorry. I think the 7193 > 6V6 > 300B with a few tweaks could turn out to be a very good amplifier. Keep me posted and feel free to ask any more questions! The main reason I support the choke load so much it because they can allow the extraction of every last bit of super linear gain from those old beautiful triodes, like the 26 and VT-25. I think I will be trying some chokes though with a 12B4A line stage to see if I see any increase in detail, dynamics, etc...
Cheers
James
I would say for the previous listed schematic that you posted there isn't really to much that you would have to change. Tweak the values for the 6J5 input tube since would use a 7193. Other than that the front end would stay almost the same since the 7193 and the 6J5 are similar tubes. As for the 6V6 driver, personally I would triode strap it, though others can pipe in regarding this decision. Obviously you would have to figure the new component values, but other than the the circuit would look the same, it would just be a lot beefier. For the choke you will have to mind the voltage a little bit and make sure it doesn't exceed the tubes max, the choke does not drop as much voltage as the resistor would. The choke or CCS loads the tube different, it presents a more straight load line. The tube will have a gain almost equal to it's mu. A plus too with the design that you mentioned is that you should be able to eliminate the cathode bypass cap in the driver stage, loosing a source for possible distortion. It will allow the tube to swing a lot more voltage, I don't remember how much more, but I think it is closer to the B+ on the tube, or more, I cannot remember, please someone jump in on this. As a small added benefit you get a little better PSRR for that stage. I think in theory you should be able to even better drive the 300B and the choke load should be more dynamic and detailed.
Just tweaking the values though and keeping the 6V6 RC coupled to the 300B would still have more than enough drive. Like I said before...I think... the triode 6V6 is about like 4 or so 6SN7's all together, as long as the circuit is designed right. I would say if you decide to go this route that I would get some help and calculate the resistor/capacitor values then down the road try a choke load. You could also start by trying a choke load with a 150H Hammond choke, they are about $18.00 or so, much cheaper than Llundahl's, James' etc... Though Electra-Print anode chokes are only about $50 average each.
You can find some information by searching around, and will probably find people much more versed in the use of such devices than I am, I am just a supporter for now. As for CCS's they are similar to chokes but I know much less about them, that is why I didn't touch on them. There are some here though that are very versed in the use of CCS's both as anode loads and cathode loads. I think your design would look awesome with some ST "coke bottle" 6V6's, I bet it would sound good too. I hope this may have answered some questions, or maybe I just made more questions for you, if so, sorry. I think the 7193 > 6V6 > 300B with a few tweaks could turn out to be a very good amplifier. Keep me posted and feel free to ask any more questions! The main reason I support the choke load so much it because they can allow the extraction of every last bit of super linear gain from those old beautiful triodes, like the 26 and VT-25. I think I will be trying some chokes though with a 12B4A line stage to see if I see any increase in detail, dynamics, etc...
Cheers
James
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