In my first test I am using the same power supply for both channels and both stages but in the final version I will use an LC section to separate the driver and probably also the channels will be separated.
hi andrea,
I'm working to an amplifier with the 810 as power tube, until today using a 6em7 like pre/driver in a three stages topology. The 810 works at 1250v 60ma with a load of 10k, and the idea to put all in only to stage is amazing. I tried with 6c45pe choke and interstage 1:1 5k iron, but there was not enoght dynamic, also with a mu stage of 27 where there wasn't quite punch...and so on. Now the opportunity of the 6hv5a is greedy: two stage that work more of less at the same high potential. The 810 works also with a simple pentode likes ef37/6j7 cause doesn't need a great swing to grid driving, so the d3a trasformer loaded as you suggested in gm70 would be enogh, but would compare the appeal of a tube that can push everywhere?
In this way do you think is better get an iterstage trasformer 1:1 than 1:2, has a specific name the bartolucci' one tested?
thanks and compliments for works
luigi
I'm working to an amplifier with the 810 as power tube, until today using a 6em7 like pre/driver in a three stages topology. The 810 works at 1250v 60ma with a load of 10k, and the idea to put all in only to stage is amazing. I tried with 6c45pe choke and interstage 1:1 5k iron, but there was not enoght dynamic, also with a mu stage of 27 where there wasn't quite punch...and so on. Now the opportunity of the 6hv5a is greedy: two stage that work more of less at the same high potential. The 810 works also with a simple pentode likes ef37/6j7 cause doesn't need a great swing to grid driving, so the d3a trasformer loaded as you suggested in gm70 would be enogh, but would compare the appeal of a tube that can push everywhere?
In this way do you think is better get an iterstage trasformer 1:1 than 1:2, has a specific name the bartolucci' one tested?
thanks and compliments for works
luigi
Hi Luigi
I also built a 810 SE 5 years ago, but mine is in positive bias for 810 ( Vp 750v Ip 140ma Vg around +16v), #26 direct couple to a 300B drive a step down interstage 1:0.8, sound wonderful. I using it in sub-woofer section under 80 HZ
Tony KY Ma
hi tony ,
compliments, you used all dht, my favourite preamplifier tube, the 26, and the 300b in the place where probably works better, under low ra and enough swing, as driver to a positive grid transmitting tube. I appreciate the sound of 810 for the microdynamics which makes assimilate to the 45, if you listen to it throgh the subwoofer surely obtain granitic basses, with out tails!
I choose A1 class and would like to build a two stages amplifier, less is better in my opinion so I would try with the 6hv5a...
Four years ago I build an amplifier in A2 class with 833a as final, drived by 845 interstage 10k loaded 3:1 and e80l as input stage. 1100v rp 833a, 31/35 v bias, 910 rp 845, -125/130v bias, psu all tube, 866a, rectified with choke input filter, do you image how great was the swinging choke for anodic filter? That experience promted me to semplify the circuits.
Thanks for your tip.
Luigi
compliments, you used all dht, my favourite preamplifier tube, the 26, and the 300b in the place where probably works better, under low ra and enough swing, as driver to a positive grid transmitting tube. I appreciate the sound of 810 for the microdynamics which makes assimilate to the 45, if you listen to it throgh the subwoofer surely obtain granitic basses, with out tails!
I choose A1 class and would like to build a two stages amplifier, less is better in my opinion so I would try with the 6hv5a...
Four years ago I build an amplifier in A2 class with 833a as final, drived by 845 interstage 10k loaded 3:1 and e80l as input stage. 1100v rp 833a, 31/35 v bias, 910 rp 845, -125/130v bias, psu all tube, 866a, rectified with choke input filter, do you image how great was the swinging choke for anodic filter? That experience promted me to semplify the circuits.
Thanks for your tip.
Luigi
Hi Luigi
I met 833A in WAVAC room in CES 4 years ago but it didn't give me surprise, I think 833A is not only that, maybe the setting not too good only use CD for showing. every person has his own favor I like DHT better than in-direct include rectifier tube, real triode better than others, SE class A is the best. also positive bias is better than negative bias in the out-put section, silver better than cooper, tape and vinyl better CD, and no silicon except regulator and rectifier in filament supply
Happy New Year Tony KY Ma
Why use class A2 tubes with positive grid ?
It is quite impossible drive these tubes in a correct way and always there are problems, the best should be cathode driven to have a costant current.
On teh market there are many good and cheap class A1 tubes very easy to drive like GM70, 211, 845 and 813 in triode connection.
The 90% of the costs in a tube amplifier are the transformers, not the tubes.
It is quite impossible drive these tubes in a correct way and always there are problems, the best should be cathode driven to have a costant current.
On teh market there are many good and cheap class A1 tubes very easy to drive like GM70, 211, 845 and 813 in triode connection.
The 90% of the costs in a tube amplifier are the transformers, not the tubes.
Why in positive bias ? because they sound different , I like this kind of sound with real body, sound solid, and this way was found by Mr. Koichi Shisido but sadly he passed away in 1997. in Japan he still have a lot of fans, tubes are not expansive but in use of interstage transformer cost a little bite, different out-put tube in different sound . in my system I use 826 for supper high, 809 in mid-high, 812A in mid-low, 810 in sub- low
Tony KY Ma
Ciao Andrea, è da qualche anno che sbircio i tuoi lavori, complimenti!
qual'è la versione definitiva del tuo ampli con la 845?
ciao grazie a presto!
Massimiliano
This is an English speaking forum. If you wish to post in another language, please post also in English.
Thank you.
Thank you.
Hi Luigi
As you like one stage gain and drive, do you know WE437A ? this tube is perfect except a little expansive , mu is high 43, Rp is low 1K current also high 30ma and sound perfect, I did project with as one stage to 826 or 838 and 805 and other tube 5876 a pencil triode also high mu but Rp 4K and price cheap, I did a amp use it in one stage to 809 very simple circuit. and I did post in here title of NASA space age tube use in audio
Tony KY Ma
Massimiliamo would like to know my last version of this amplifier.
I have decided to use the 6HV5A like driver loaded with the last Bartolucci 2:1 interstage transformer.
This combination give estreme performances as sound and measurements.
I have decided to use the 6HV5A like driver loaded with the last Bartolucci 2:1 interstage transformer.
This combination give estreme performances as sound and measurements.
I don't although I have the meter, I measure the out-put only even without the scop, What I mainly to do is judge by listen and compare, distortion is not a issue to me so all my amp is no feedback, from phono stage to power. maybe a lot of people are not agree to these but a 60 HZ signal with 0% distortion still a hum . I don't think who will compare which hum sound better
Tony KY Ma
Tony KY Ma
I agree with tony, if the circuit works well as in the project, the final answer came from listening. I'm trying to drive 810 in A1, but probably the best result is in positive grid, cause I dind't find a nice driver stage until today.
417, 437, 5112, 6c45pe, e55l or d3a as triode,..., no one has enough personality to balance the 810 one, and it's not something you can see on the screen, simply listen.
In this way I prefer the 810' than 845' sounds, to much bass for my 2" driver, the horn is too squanker with this triode. Better the research with 810, the 211 instead needs a great load and 100th has les definition.
The idea with 6hv5a would be great, but we have to listen to the result, on paper I know a lot of great amplifier, the real sound is then different.
810 in a1 or 810/838 in a2, this is my future.
I am not agree with you,
it is true that an amplifier should have a good sound and we are not interested to get the same performanes of a solid state amplifiers with lot of feeedback but there are some main points to keep in consideration like a minimun damping factor and a moderate distortion.
The more difficult amplifier to design is a class A2 with positive grid because the driver see a variable load so in these case I consider valid only the cathode driven configuration.
it is true that an amplifier should have a good sound and we are not interested to get the same performanes of a solid state amplifiers with lot of feeedback but there are some main points to keep in consideration like a minimun damping factor and a moderate distortion.
The more difficult amplifier to design is a class A2 with positive grid because the driver see a variable load so in these case I consider valid only the cathode driven configuration.
A wonderful tube that unlike the 6c45 can take gobs of current without generating high levels of harmonics above the 3rd or 4th. Very microphonic though so requires caution in use.
no problem, should have different opinion, that why we are to discuss , good sound has a wide level and with personal favor too, first I don't like the performance of cathode driven configuration, the key point of Mr, Shisido's design is use a power or semi power tube to drive with a transformer, similar to drive a speaker, the only thing different is have DC current in both side of the transformer. if they flow in the same way then it will be a huge in size, so let it in opposite direction then cancellation of magnetism to make size smaller and react fast, I believe this one make the sound different, My listening judge is first the sound stage has to be away from the speakers no matter what kind speaker system in use, image focus , emotion, clearness, weight of image's body, when turning the volum that mean the sound stage is move forward or geting away is not only louder or not, etc, I am not too mind in frequency respond because most problem in speaker system,
Tony KY Ma
Tony KY Ma