Hello James, they are indeed bloody heavy!! The 100watters I have here have a similar heft to them as a 400VA mains transformer. They are also excellent performers despite the weight which in some output transformer designs results in HF roll off due to inter-winding capacitance. Not so with the ones I have as they don't run into trouble until 60Khz or so. Work fine at full power down to around 10Hz too, maybe down a decibel or so. Excellent transformers.
Maybe now as Eli calls it you have so much "magnetic headroom" you could think about using some MOSFET followers to drive the output valves grids. This would allow AB2 but more importantly in the real world gets you away from any blocking distortion. Check out the 6L6 AB2 thread for George's pretty thorough run through.
Obviously you will need to tune the feedback components to suit your transformers but this is relatively easy given the performance of them. Morgan Jones gives a good way of doing it using an old 500pf air spaced dual variable capacitor mounted in a plastic lunch box for insulation.
Cheers
Matt
Maybe now as Eli calls it you have so much "magnetic headroom" you could think about using some MOSFET followers to drive the output valves grids. This would allow AB2 but more importantly in the real world gets you away from any blocking distortion. Check out the 6L6 AB2 thread for George's pretty thorough run through.
Obviously you will need to tune the feedback components to suit your transformers but this is relatively easy given the performance of them. Morgan Jones gives a good way of doing it using an old 500pf air spaced dual variable capacitor mounted in a plastic lunch box for insulation.
Cheers
Matt
No worries James, I think you can really make the ultimate beast now. You may even end up needing speakers that can go down to 20Hz or so. Possibly new neighbors too😎👍
Sorry Nick, I just read back through again. You are not James but Nick. I do apologise, is James your cat's name? Ours is called Sparkplug and or Wingnut. It just depends on his behaviour that day.
Well, it is simply because I am speechless. Everything is looking so bloody well nice🙂 .
Did a key word search without success for the schematic diagrams you are using.
Perhaps you can supply the link?
I will up load the other version k8010 which is slightly different .. more bias and uses KT88 valves .. I have changed out the output transformer which is the biggest single improvement but very expensive ..
Ok just a few pictures .. this build seems to be taking ages. anyway you will see I have spaced out the pre driver valves as in this version I wanted to put the valves on show. So I will have to suspend the PCB under the main chassis plate. I used braided copper then heat sleeved the conductors .... thoughts hope this will work OK.
Also I have used small bolts with solder tags for the valve terminations so will take more strain off the PCB tracks for ongoing repairs / mods / maintenance for example ... the solder tags are also soldered to the PCB tracks. any way once the amplifier is complete all will make sense .. pictures in the next post
Also I have used small bolts with solder tags for the valve terminations so will take more strain off the PCB tracks for ongoing repairs / mods / maintenance for example ... the solder tags are also soldered to the PCB tracks. any way once the amplifier is complete all will make sense .. pictures in the next post
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I like the solder tag thing Nick. May be a good idea to get some nickel plated brass washers and put a little grease on the side the tag bolts up to (to stop the solder wicking round to the face the tags bolt to) before sweating them on to the board. Directly bolting tags to a tinned PCB track will cause problems over time. There are proper inserts for this but they are crazy expensive unless you buy in thousands.
Any pics with the new output transformers?
Cheers
Matt.
Any pics with the new output transformers?
Cheers
Matt.
Hello .. sorry for the delay, to many projects on the go
will update more over the weekend
busy with the JLH mosfet amplifier and the Stan Curtis class A power amplifier at the moment 🙂
Hello samb
Hope you are well .. nearly completed the project so will update soon, to be honest lost some interest in the project but have some more enthusiasm now so will push to complete.
How are your units running ? all Ok still enjoying the sound ?
all the best
hello nick,
happy to hear news from you
yes i am running my units and they perform ok.
But remenber they are modded.
( i send you one year ago the modifications to allow you to implement them)
now i run the amps with only two EL34 as my speakers (yamaha NS1000M) did not need a lot of power. And sound seems to me better.
Last i had problems with the power on toggle switch ....
best regards
sam
happy to hear news from you
yes i am running my units and they perform ok.
But remenber they are modded.
( i send you one year ago the modifications to allow you to implement them)
now i run the amps with only two EL34 as my speakers (yamaha NS1000M) did not need a lot of power. And sound seems to me better.
Last i had problems with the power on toggle switch ....
best regards
sam
Hello Sam
Yes very great full for those mods so going to apply them to my next build .. looking forward to the challenge .. keep in touch
Yes very great full for those mods so going to apply them to my next build .. looking forward to the challenge .. keep in touch
Did you ever finish these? I ended up getting one, and wonder if its yours. Let me know. We've enjoyed them immensely and have made a video review of it. I want to know if its yours.
Velleman Class A K8010 Tube Monoblock Amplifiers - Review! - YouTube
Velleman Class A K8010 Tube Monoblock Amplifiers - Review! - YouTube
Hello thanks for the post
These are the same as the ones I make but this particular example is not made by me as is the original Velleman version.
Mine are different with some improvements added from experience of making so many of them in the past .. I do both versions EL34 and KT88 and 6CA7 valves
Have attached a 6CA7 version as work in progress .. all the best
These are the same as the ones I make but this particular example is not made by me as is the original Velleman version.
Mine are different with some improvements added from experience of making so many of them in the past .. I do both versions EL34 and KT88 and 6CA7 valves
Have attached a 6CA7 version as work in progress .. all the best
Attachments
Thanks,
I've heard I can set this to use those tubes. They're very similar but provide a little less power on other AMPS.
I've heard I can set this to use those tubes. They're very similar but provide a little less power on other AMPS.