They do, and it looks like they also have 6DQ6B which seems to be about the same thing as 6AV5GA but with a top cap. Most interesting.
Perhaps I can start building a breadboard this weekend. Nothing beats real life experiments and I have several tubes to try as drivers (and input stages) before I buy any more. There's a very real chance that a Mosfet will be, by magnitudes, better than any realistic tube option😱
It is the same thing with a top cap. Often the cap type versions can be had cheaper - but then you’ve got to pay for the cap. But if you want it to look stone knives and bear skins, or look like a little person (with a head) then cap is the way to go. Im pretty sure it uses the little bitty cap, not the one that fits the 807 - may want to check on that. I’ve got some compactrons in the 17 watt range that use the smaller cap, and the BQ6 is 11 watt.
Of course mosfets are better. But a finned aluminum heat sink loses a beauty contest with a tube. Any tube. I like old technology. It’s fun. If it wasnt, all I’d be building are 5000 watt PA amps. I’m glad I rediscovered tubes. What I found was with proper engineering (from decades of SS work) how good they can actually sound. And the cool factor is 12 parsecs ahead no matter how you look at it.
Of course mosfets are better. But a finned aluminum heat sink loses a beauty contest with a tube. Any tube. I like old technology. It’s fun. If it wasnt, all I’d be building are 5000 watt PA amps. I’m glad I rediscovered tubes. What I found was with proper engineering (from decades of SS work) how good they can actually sound. And the cool factor is 12 parsecs ahead no matter how you look at it.
Hear, hear!
If the goal only was to get as good sound as possible I would just dust off my old Hiraga Le Monstre clone and be done with it. I've built dozens of tube circuits (with varying degrees of ambition) over the last twenty years and few, if any, can compete with the Monstre. Though, designing and building tube stuff is a hobby on it's own, much more satisfying than assembling pcbs and putting them in boxes along with some caps and transformers.
When it comes to looking spectacular, the 808 is definitely in the higher divisions.
Even though mosfets or modern, high gm tubes would make better drivers, I think they deserve being surrounded by tubes that harmonize visually (although I have this idea about a tube/fet hybrid cascode follower that would combine the high performance of a fet with the slow startup from a tube...if it works).
Here's a picture of the output tubes and transformers paired up with CV1135 input tubes and PE06/40N (~807) drivers on a copper sheet.
With a little imagination, I can picture this playing background music in some steampunk opium den...or brothel
A man of culture!
Please tell us more about both the amps and the white horn to the right in the picture, it looks very similar to the 695Hz LeCleach horns I use in my livingroom system.
Here is the schematic but i have changed the loading of the first stage to CCS now.
The horns are azura JMLC 1100 hz full roll back on hf10ak, mids 340hz concrete JMLC horns on BMS 4596nd. It's an active system also using 45 tube amps. I have painted the small horns black since that picture and it look better.
The horns are azura JMLC 1100 hz full roll back on hf10ak, mids 340hz concrete JMLC horns on BMS 4596nd. It's an active system also using 45 tube amps. I have painted the small horns black since that picture and it look better.
Attachments
Looks like a an absolutely lovely system!
Interesting choice of interstage transformer, I assume you don't run it in inverting mode to cancel DC in the core?
A closer pic of the "christmas tree" amp below the left mono block would also be most welcome, there must be some interesting tubes involved there! 🙂
Interesting choice of interstage transformer, I assume you don't run it in inverting mode to cancel DC in the core?
A closer pic of the "christmas tree" amp below the left mono block would also be most welcome, there must be some interesting tubes involved there! 🙂
126b are bifilar and only work well in one orientation. My first experiment they were backward and had very limited bandwidth then I found info in this forum about reversing all my connections.
The Christmas tree is a music transport and raspberry pi player using moode audio and all Ian Canada modules. It use super capacitor and lithium battery for the spdif output. Really nice unit and fun thing to build. It feed the DEQX on the right.
The Christmas tree is a music transport and raspberry pi player using moode audio and all Ian Canada modules. It use super capacitor and lithium battery for the spdif output. Really nice unit and fun thing to build. It feed the DEQX on the right.
That's what I though, bifilar transformers have horrible bandwidth when wired out of phase. I have a pair of LL1671 / 50mA ITs that I intend to try once I have a prototype up an running. These transformers can be wired as 1:1, 2:1 or 4:1 and the generous airgap leaves some interesting options to try. Not sure it will work very well though, I seem to recall that the 808 needs an input signal that swings from around +25-30V at idle up to 60-70V and down to -15V or so for full output and I know from recent experiments with other tubes that the Lundahls don't behave very well at the point where the grid current suddenly stops flowing.
Aaaah I see. In the picture, it looked like a tube amp with some very exotic tubes 😀
After all these years it's about time to hear what the 808 actually sounds like. Breadboard time!
A pair of 2,5-5k:0-4-8-16R OPTs, 40H 50mA cathode chokes for the drivers, LL1660 10mA hi-Z ITs, LL1671 50mA lo-Z ITs, 807 driver tubes and a single 6SN7 input stage (more practical than two CV1135 at this stage). A pair of Mosfet followers will be added too, and of course a all the necessary power supplies.
This should be enough to keep me busy testing various low gain, low NFB topologies for quite a while.
A pair of 2,5-5k:0-4-8-16R OPTs, 40H 50mA cathode chokes for the drivers, LL1660 10mA hi-Z ITs, LL1671 50mA lo-Z ITs, 807 driver tubes and a single 6SN7 input stage (more practical than two CV1135 at this stage). A pair of Mosfet followers will be added too, and of course a all the necessary power supplies.
This should be enough to keep me busy testing various low gain, low NFB topologies for quite a while.
I'm following this with interest.
Just started testing for a DA41 or 5514 PP with ECC31 input and driver, will try fet followers at first. I will also try this with 813, but not A2.
I have not decided what OPT to use yet, high Ra may be a problem, and 150w is a lot of iron.
Those speakers behind does not need a lot of power ? 😉
Br
/Figge
Just started testing for a DA41 or 5514 PP with ECC31 input and driver, will try fet followers at first. I will also try this with 813, but not A2.
I have not decided what OPT to use yet, high Ra may be a problem, and 150w is a lot of iron.
Those speakers behind does not need a lot of power ? 😉
Br
/Figge
Cool tubes, I think I have one of each on the shelf. On second thought, it's a T40 and a 5514.
Sounds like you're aiming for AB2, that would take some serious output iron. Perhaps Toroidy in Poland has something that would fit? They have PP transformers with CFB windings, that would take care of the high Ra.
Those speakers are a blessing and a curse: I don't really need gain in my power amps anymore, a simple mosfet buffer between the (TVC) preamp and the speakers would be perfectly sufficient for any civilized listening. As a consequence, they are very unforgiving for hum and noise issues and only a few of my old DIY amps are quiet enough to actually use.
Got my russian GU-32s yesterday: I don't know, something with a black bakelite base would look better.
...and the winner is: 807 drivers and a single 6SL7 shared between channels as input stage:
The amp is done and it sounds quite good but the power supply is currently being rebuilt.
Meanwhile I'm planning for round 2, featuring the smaller but very nice looking T20/TZ20 as output tubes.
Here pictured next to some potential candidates, first out PL36 as driver and CV1135 as input tube. A decent looking combo and the PL36 has higher gm than most other octals :
6AV5GA and CV1135, also quite nice looking but a bit low gm for cathode follower duty:
807, low gm and already done once:
An odd one: the russian GU32. Half-decent gm with both sections in parallel but not very good looking:
IRF840, definitely the best device for a follower but rather nasty looking and I like the slow start/bias delay provided by an indirectly heated cathode follower:
Compromising the vintage look by using more modern tubes with (much) higher gm probably be very benificial. I just took something from the shelf for the picture but let's pretend that the noval tube is a 6E5P, PL802 or something like that:
The amp is done and it sounds quite good but the power supply is currently being rebuilt.
Meanwhile I'm planning for round 2, featuring the smaller but very nice looking T20/TZ20 as output tubes.
Here pictured next to some potential candidates, first out PL36 as driver and CV1135 as input tube. A decent looking combo and the PL36 has higher gm than most other octals :
6AV5GA and CV1135, also quite nice looking but a bit low gm for cathode follower duty:
807, low gm and already done once:
An odd one: the russian GU32. Half-decent gm with both sections in parallel but not very good looking:
IRF840, definitely the best device for a follower but rather nasty looking and I like the slow start/bias delay provided by an indirectly heated cathode follower:
Compromising the vintage look by using more modern tubes with (much) higher gm probably be very benificial. I just took something from the shelf for the picture but let's pretend that the noval tube is a 6E5P, PL802 or something like that:
Hi @Fuling !
I was akeen to think that the PL36 was the nicest mate aesthetically speaking to your 808... But OK : the 807 is fine too !
Long ago in France we had a company called RADIOFOTOS GRAMMONT which produced "blue" glass tubes...
T
I was akeen to think that the PL36 was the nicest mate aesthetically speaking to your 808... But OK : the 807 is fine too !
Long ago in France we had a company called RADIOFOTOS GRAMMONT which produced "blue" glass tubes...
T
Beautiful tubes! Never heard if that brand before.
PL36 would also make better cathode followers but the limited number of pins on the PSU/amp connector more or less forced me to pick a tube with the same heater voltage as the input tube.