gm70 are not very expensive they cost about 50$ a pair.. less than a good KT88 possibly svetlana brand and from a kt66..
second i believe that a KT88, KT66, 6L6 are not intended for a SE class A
they are good for a puss-pull design i got my self a KT88 with 6SN7GTB and got quite good results.
if you do choose the gm70 you will need very good OTP. you are running near 1kv region and the primary must have good isolation from the secondary. (corona discharge)
or you can run them with 700V B+ and get about 10 to 15w with still very good sound!!
second i believe that a KT88, KT66, 6L6 are not intended for a SE class A
they are good for a puss-pull design i got my self a KT88 with 6SN7GTB and got quite good results.
if you do choose the gm70 you will need very good OTP. you are running near 1kv region and the primary must have good isolation from the secondary. (corona discharge)
or you can run them with 700V B+ and get about 10 to 15w with still very good sound!!
Hello nomiconxp
Thank you for the advise!
It look like good idea, but to start somewhere (collect, buy the parts) I have to have a proven (working) schematic..
Sometimes to me even that is a problem. Almost 20 years I built my last tube amp.
After only I built SS amps.
Are you willing to share your amp schematic??
You can send it to gaborzoltan2@gmail.com
I like the GU50 tubes to , but when I open the wavebourn website I found at least 10 or more schematic.
I have no idea which one would work, or work for me.
I'm not a amp designer (not a technician) all do I have some experience.
If I have the schematic I can build it.
With out I'm lost in the tube world.
Greetings gabor
Thank you for the advise!
It look like good idea, but to start somewhere (collect, buy the parts) I have to have a proven (working) schematic..
Sometimes to me even that is a problem. Almost 20 years I built my last tube amp.
After only I built SS amps.
Are you willing to share your amp schematic??
You can send it to gaborzoltan2@gmail.com
I like the GU50 tubes to , but when I open the wavebourn website I found at least 10 or more schematic.
I have no idea which one would work, or work for me.
I'm not a amp designer (not a technician) all do I have some experience.
If I have the schematic I can build it.
With out I'm lost in the tube world.
Greetings gabor
Hi Gabor!
i will draw it! and scan it and will be posting to you to see it..
this is my latest amplifier i made, so the schematic is in my head!
i want to make some changes!
now i am running them with self bias...!
1) I want to change them to custom bias!
2) I want to configure the driver stage replacing the anode resistor with a choke loaded..
I think i will get better results.. if not! I'm open to any advise every one can give me!!
3) In my opinion you will build a good amplifier!!
if you customize something to your own needs!!
fixing something from another some times is a good thing to go...
but we are talking here about taste!! and not every one of us has the same taste!!!!
to some will sound great, to you will otherwise.. that doesn't mean that there aren't any good schematics on the web...
once again if i am wrong somebody correct me!!
i will help you with every thing you need!! soon a possible a will send you some drawings! you can do what ever you like with them!
try to experiment!!!!!! 🙂
best regards Nomikos!!
i will draw it! and scan it and will be posting to you to see it..
this is my latest amplifier i made, so the schematic is in my head!
i want to make some changes!
now i am running them with self bias...!
1) I want to change them to custom bias!
2) I want to configure the driver stage replacing the anode resistor with a choke loaded..
I think i will get better results.. if not! I'm open to any advise every one can give me!!
3) In my opinion you will build a good amplifier!!
if you customize something to your own needs!!
fixing something from another some times is a good thing to go...
but we are talking here about taste!! and not every one of us has the same taste!!!!
to some will sound great, to you will otherwise.. that doesn't mean that there aren't any good schematics on the web...
once again if i am wrong somebody correct me!!
i will help you with every thing you need!! soon a possible a will send you some drawings! you can do what ever you like with them!
try to experiment!!!!!! 🙂
best regards Nomikos!!
Thank you very much!!!🙂
The GM70 is the same tube (or close) as 845??
For example like these
845 SE1
I ask these question because more info available about the 845 tube also transformers etc..
If you still work on your amp don't be hurry with the schematic.
Which type tube U use ? I mean the copper plate or the graphite. I read the cooper much better.
Actually now that not important, I can try out both tube type after I built the amp.
Ones I have enough information (some support) I can start look for the parts.
Wavebourn I like your advise to, unfortunately your schematic you posted is not available.
From your website I don't know which schematic to chose , you know a lot of schematic there.
I read good thinks about the GU50 tubes also..And those are cheap and available to.
Thanks one more time.
Greetings
The GM70 is the same tube (or close) as 845??
For example like these
845 SE1
I ask these question because more info available about the 845 tube also transformers etc..
If you still work on your amp don't be hurry with the schematic.
Which type tube U use ? I mean the copper plate or the graphite. I read the cooper much better.
Actually now that not important, I can try out both tube type after I built the amp.
Ones I have enough information (some support) I can start look for the parts.
Wavebourn I like your advise to, unfortunately your schematic you posted is not available.
From your website I don't know which schematic to chose , you know a lot of schematic there.
I read good thinks about the GU50 tubes also..And those are cheap and available to.
Thanks one more time.
Greetings
Hi Gabor,Glad you finally come around with your decision on DHT triodes
with nomiconxp's help.Go for Lundahl's 10K ohm output transformers although
it may cost slightly more over there but it's has good quality,there's one
thing though being made of C cores and has no covers they are ugly to
look at in all likelyhood most people mount them underneath unless you want
to make a cover for them on top.Plus the high voltage!
with nomiconxp's help.Go for Lundahl's 10K ohm output transformers although
it may cost slightly more over there but it's has good quality,there's one
thing though being made of C cores and has no covers they are ugly to
look at in all likelyhood most people mount them underneath unless you want
to make a cover for them on top.Plus the high voltage!
Hi Gabor,
I have built this amp taken from Wavebourn site using GU-50.
My friend who has a 6550 amp says this amp sounds way better than his custom designed amp.
http://wavebourn.com/forum/download.php?id=487&f=7
I have built this amp taken from Wavebourn site using GU-50.
My friend who has a 6550 amp says this amp sounds way better than his custom designed amp.
http://wavebourn.com/forum/download.php?id=487&f=7
Hello quikie22
Thank you for your post, and good to know you like your amp.
Are you sure Wavebourn gave me that schematic to me? To me a bit look to complex that amp.
Did He gave that schematic to you or pick one from his website? I have all respect to Wavebourn , I know He is a great designer.
I sow many of his amp on the forum , all my respect to him!I'll wait on Nomikos, GM70 tube also nice..
After I decide which amp will chose.
Thanks one more time.
Good to know there are folks on the forum willing to help!!!
Greetings Gabor
Thank you for your post, and good to know you like your amp.
Are you sure Wavebourn gave me that schematic to me? To me a bit look to complex that amp.
Did He gave that schematic to you or pick one from his website? I have all respect to Wavebourn , I know He is a great designer.
I sow many of his amp on the forum , all my respect to him!I'll wait on Nomikos, GM70 tube also nice..
After I decide which amp will chose.
Thanks one more time.
Good to know there are folks on the forum willing to help!!!
Greetings Gabor
guy's let's talk about something..
In all the discussion we are talking only about the output tubes..
what about the driver stage!
*** we all know that the total watt rms dissipation it equally depends by the driver stage too.!
the sound, the THD, and the voltage swing!!
in the whole process would i like helping gaborbela to build an amplifier of his own!!
what can everybody say about the D3A, 12GN7A..?
they are good pentodes! with triode characteristics!
and connected in triode even beter THD!
and the first has amplification factor greater than 70!!
In all the discussion we are talking only about the output tubes..
what about the driver stage!
*** we all know that the total watt rms dissipation it equally depends by the driver stage too.!
the sound, the THD, and the voltage swing!!
in the whole process would i like helping gaborbela to build an amplifier of his own!!
what can everybody say about the D3A, 12GN7A..?
they are good pentodes! with triode characteristics!
and connected in triode even beter THD!
and the first has amplification factor greater than 70!!
this is a nice amplifier with great characteristics!!
me an a friend build this amplifier for him! and we were very happy with the results!
i got a few interesting ideas from it!! tomorrow i will post the schematic that i draw!
An externally hosted image should be here but it was not working when we last tested it.
me an a friend build this amplifier for him! and we were very happy with the results!
i got a few interesting ideas from it!! tomorrow i will post the schematic that i draw!
Cheap, "big" (well, it's all relative) power can be found with the Shuguang EL156. Easy to drive too. Ultralinear or Pentode will make 15-20Ws, depending on voltage/current selected. Did I mention easy to drive? I just used a single EF86 in pentode and got excellent results with some GNFB. Plenty loud with some 90dB KEFs or my big UREI 813A speakers.
Hello nomiconxp
Thank you for the schematic! Let see what other experts will think about.
Also I found several GM70 schematic.. To me the inter stage transformer a bit new ... All do nice schematics!
I found in Andrea website also similar amp.
kstagger
To me more important the quality. I know these not will be cheap, may be the tubes but high voltage caps etc those are pricy.
If the amp know 8-15 Watts that extra.. 8W min.I think. If you listening often classical you know those recoded sometimes low sometimes in high volume..
If get distorted when go high volume better to stick with my SS amps.
How I stated these would be my last amplifier project! I want to build something I can live with.
Greetings gabor
Thank you for the schematic! Let see what other experts will think about.
Also I found several GM70 schematic.. To me the inter stage transformer a bit new ... All do nice schematics!
I found in Andrea website also similar amp.
kstagger
To me more important the quality. I know these not will be cheap, may be the tubes but high voltage caps etc those are pricy.
If the amp know 8-15 Watts that extra.. 8W min.I think. If you listening often classical you know those recoded sometimes low sometimes in high volume..
If get distorted when go high volume better to stick with my SS amps.
How I stated these would be my last amplifier project! I want to build something I can live with.
Greetings gabor
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That circuit is on Wavebourn site. 🙂
I simplified the circuit by using a resistor as load for the first stage instead of gyrator (BSP225 circuit).
The driver stage is excellent thus explaining why the sound was so good. The cathode follower using the 6N6P ensures optimum drive voltage and current for the GU-50 thus ensure best power output and sound. You can follow our discussion and thread on the GU-50 cct on Wavebourn site.
I simplified the circuit by using a resistor as load for the first stage instead of gyrator (BSP225 circuit).
The driver stage is excellent thus explaining why the sound was so good. The cathode follower using the 6N6P ensures optimum drive voltage and current for the GU-50 thus ensure best power output and sound. You can follow our discussion and thread on the GU-50 cct on Wavebourn site.
Hello quikie22
Wavebourn posted one schematic in the site to me but for some reason the schematics not available.
These GM70 tube has some charm (of course the high voltage)
Do the UG50 sound as good as the GM70? Of course here the used parts influence the sound!
I like both tube! The GU50 probably would be cheaper a bit because lower voltage.. Unfortunately I never heard either!
I found also a couple GM70 schematics, here is one of them
gm70 se
I would prefer something with out inter stage transformers (those are pricy)that money I would spend on a good OP transformer
Choke on or two is OK..
Greetings
Wavebourn posted one schematic in the site to me but for some reason the schematics not available.
These GM70 tube has some charm (of course the high voltage)
Do the UG50 sound as good as the GM70? Of course here the used parts influence the sound!
I like both tube! The GU50 probably would be cheaper a bit because lower voltage.. Unfortunately I never heard either!
I found also a couple GM70 schematics, here is one of them
gm70 se
I would prefer something with out inter stage transformers (those are pricy)that money I would spend on a good OP transformer
Choke on or two is OK..
Greetings
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the circuit i have passed you is the finalised version for a single-ended GU-50 amp. We discussed several possible versions with MOSFET followers and tube followers. As I was keen to keep the the follower to tube, we came up with this final design.
AS for the sound, it sounds great. I have not heard the GM-70 so I cannot comment on its sound. I have listened to 6550, FU-13 (813 analog), EL84 and many solid state amps, including the highly regarded Pass Labs F5. The Wavebourn GU-50 Gubernator beats them except for the FU-13 amp. (and that is only because the FU-13 is a much higher power beast, running at >1kV voltage).
My friend had a copper plate GM-70 and he says it's the best amp he has ever built. But be warned, it runs at 1.4kV and a fluorescent lightbulb held close to it will glow without being connected due to corona discharge. He took it apart as he had a 4 year old child running around the house and the amp was not worth the risk.
AS for the sound, it sounds great. I have not heard the GM-70 so I cannot comment on its sound. I have listened to 6550, FU-13 (813 analog), EL84 and many solid state amps, including the highly regarded Pass Labs F5. The Wavebourn GU-50 Gubernator beats them except for the FU-13 amp. (and that is only because the FU-13 is a much higher power beast, running at >1kV voltage).
My friend had a copper plate GM-70 and he says it's the best amp he has ever built. But be warned, it runs at 1.4kV and a fluorescent lightbulb held close to it will glow without being connected due to corona discharge. He took it apart as he had a 4 year old child running around the house and the amp was not worth the risk.
quickie22 i agreed with you playing with 1.4kV is not very nice!
I believe even if you don't have a child in the house it's not worth the risk fixing some in that region...
The gm70, 845, 211 all DHT triodes can run with lower voltage!!
why mess with 1.4kV to get SE 40-50W??? when you can work it around 800V-900V,
and get half of the power with very nice quality!!
if you bias a GM70 with 900V, 125mA, -125V and a descend driver stage capable of 80vrms you will get the 40Wrms...
not worth the risk! and second you are not fixing a transmitter amp...
I believe even if you don't have a child in the house it's not worth the risk fixing some in that region...
The gm70, 845, 211 all DHT triodes can run with lower voltage!!
why mess with 1.4kV to get SE 40-50W??? when you can work it around 800V-900V,
and get half of the power with very nice quality!!
if you bias a GM70 with 900V, 125mA, -125V and a descend driver stage capable of 80vrms you will get the 40Wrms...
not worth the risk! and second you are not fixing a transmitter amp...
Hello
I have no children, or wife etc. Mostly I live alone. But I agree with you guys ! That high voltage and even after I turn the amp of can be dangerous.
I know I have to work on the amp until I get the right sound!
One day from a tube amp I took out a 0.47 Wima capacitor , both hand was busy with the solder iron etc.
So I took it in my mouth, the capacitor got discharge when it touch my teeth. That amp run only around 400V..
Believe me it was not fan at all.
I was 20-22 years younger but I still remember.
The amp was off about 5-10min before I started to work on it.
Definitely I do not go over 1KV! No reason for that.
All do I read these tubes will sound better when we push it close to the max..
That schematic you posted with the GU50 not bad but to complex (mosfets etc) I do not understand the purpose of those semis.
Also in Wavebourn website there are some simple schematic but I'm not sure those works well.
Some schematic preliminary ...
I still wait on Wavebourn answer because he posted a schematic and it impossible to see it, to open up.
Right now 85-90% I will go with GH70 tubes.
Do the life of these tubes is a issue.
It can be used 1000 hours or more?? These question about bot tube GM70 and GU50.
If I have to replace the tubes after couple hundreds hours that can be a problem to.
It would be good to know before I start to buy the parts.
Greetings gabor
I have no children, or wife etc. Mostly I live alone. But I agree with you guys ! That high voltage and even after I turn the amp of can be dangerous.
I know I have to work on the amp until I get the right sound!
One day from a tube amp I took out a 0.47 Wima capacitor , both hand was busy with the solder iron etc.
So I took it in my mouth, the capacitor got discharge when it touch my teeth. That amp run only around 400V..
Believe me it was not fan at all.
I was 20-22 years younger but I still remember.
The amp was off about 5-10min before I started to work on it.
Definitely I do not go over 1KV! No reason for that.
All do I read these tubes will sound better when we push it close to the max..
That schematic you posted with the GU50 not bad but to complex (mosfets etc) I do not understand the purpose of those semis.
Also in Wavebourn website there are some simple schematic but I'm not sure those works well.
Some schematic preliminary ...
I still wait on Wavebourn answer because he posted a schematic and it impossible to see it, to open up.
Right now 85-90% I will go with GH70 tubes.
Do the life of these tubes is a issue.
It can be used 1000 hours or more?? These question about bot tube GM70 and GU50.
If I have to replace the tubes after couple hundreds hours that can be a problem to.
It would be good to know before I start to buy the parts.
Greetings gabor
Here are some more schematic
Hello
There are some simple schematic.
To me important to be simple at first so I can finish the project and can test it.
After I can do some upgrade,when I know it worth to invest more into the project.
Please someone comment these schematics I'll post .
Thank you
Greetings Gabor
Hello
There are some simple schematic.
To me important to be simple at first so I can finish the project and can test it.
After I can do some upgrade,when I know it worth to invest more into the project.
Please someone comment these schematics I'll post .
Thank you
Greetings Gabor
Attachments
If you want a simple GU-50 amp, this is a very well thought out one.. Look at post #66. I believe it is even simpler than the schematics you have posted 🙂
http://www.diyaudio.com/forums/tube...-triode-configuration-what-bias-points-7.html
http://www.diyaudio.com/forums/tube...-triode-configuration-what-bias-points-7.html
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gaborbela sorry for the delay i cannot find a scanner.. 🙁
but i remembered that the driver stage is like his!!
With the differences that the cathode capacitor is 2x220uf!
The anode choke is 100H 850R!
The signal capacitor is 0.47uf
And after the the two parallel 100k resistors there is still one more 47k that is connected to the grid of the GM70 for the negative -V for the biasing..
All other are simple....
There are two 47ohms 3W resistors connected in each of the cathode pins.
20V DC heater current!!
similar like Nicholas Chuas!!
And the output transformer is a 10k 250mA primary!
EI Core with 15000 gauss
The transformers from a friend that has a small local factory that is making output transformers for the amplifiers they make and sell..
The quality is the best the characteristics are even better!!!
This guy has a lot of experience, and the transformer he made me reach from 10Hz to near 60 Khz.....
it's competing lundahl, and much more companies, with the price of 50euros instead of 300 to 500 that some companies want...
but i remembered that the driver stage is like his!!
With the differences that the cathode capacitor is 2x220uf!
The anode choke is 100H 850R!
The signal capacitor is 0.47uf
And after the the two parallel 100k resistors there is still one more 47k that is connected to the grid of the GM70 for the negative -V for the biasing..
All other are simple....
There are two 47ohms 3W resistors connected in each of the cathode pins.
20V DC heater current!!
similar like Nicholas Chuas!!
And the output transformer is a 10k 250mA primary!
EI Core with 15000 gauss
The transformers from a friend that has a small local factory that is making output transformers for the amplifiers they make and sell..
The quality is the best the characteristics are even better!!!
This guy has a lot of experience, and the transformer he made me reach from 10Hz to near 60 Khz.....
it's competing lundahl, and much more companies, with the price of 50euros instead of 300 to 500 that some companies want...
GU50
Hello quikie22
Are you talking about these schematic??
Yes is nice!
How many Watt I can get from these.. I ask is good to know OT transformer size in W..
All do right now I'm more interested on GM70 I'm still open to the GU50 to.
The problem I never hear neither amp. Hard to decide.
Many DIY-ers talk about the GM70 is a great amp. Also I sow some commercial amp with that tube cost $10 000..
It has to be good to sell for that price.
That not mean the GU50 isn't good. I need to study before I buy the OT transformers.
I see these use 10K transformer the GM70 uses much lower primery.
Thank you for the help!
I'll save that schematic.
You built for yourself with the version use mosfets in the schematic??
I still didn't got any info from Wavebourn. If you go back you can see He advise one amp but I can't open the attached schematic..
Can you open that, I think is on the second page..
Greetings gabor
Hello quikie22
Are you talking about these schematic??
Yes is nice!
How many Watt I can get from these.. I ask is good to know OT transformer size in W..
All do right now I'm more interested on GM70 I'm still open to the GU50 to.
The problem I never hear neither amp. Hard to decide.
Many DIY-ers talk about the GM70 is a great amp. Also I sow some commercial amp with that tube cost $10 000..
It has to be good to sell for that price.
That not mean the GU50 isn't good. I need to study before I buy the OT transformers.
I see these use 10K transformer the GM70 uses much lower primery.
Thank you for the help!
I'll save that schematic.
You built for yourself with the version use mosfets in the schematic??
I still didn't got any info from Wavebourn. If you go back you can see He advise one amp but I can't open the attached schematic..
Can you open that, I think is on the second page..
Greetings gabor
Attachments
- Status
- Not open for further replies.