The K10A is a 10 watt class A with a tube input stage. Original thread here.
I started this months ago, but put it on hold to work on some other projects. It is my way - a strong start where I do most of the work toward completion but then I stall, fearing the project will not work or I get distracted with other things. I do eventually finish everything I start (talk to my x wives 😀 ).
Glen designed the amp and provided the boards. This takes most of the "what if" factor away. I did get one channel up and running a couple months ago as mentioned in the K10A thread. It works very well.
The boards with the outputs and drivers mounted on my home made heatsinks:
The raw material for the rest of the chassis:
And the progress I had made initially. The chassis was mostly finished.
I have now committed myself to finishing this amp. In order to persuade myself to spend time in my home office doing business related work (I hate doing
) I have decided that this will be the destination for this amp playing on a new pair of bookshelf speakers (next project).
I started this months ago, but put it on hold to work on some other projects. It is my way - a strong start where I do most of the work toward completion but then I stall, fearing the project will not work or I get distracted with other things. I do eventually finish everything I start (talk to my x wives 😀 ).
Glen designed the amp and provided the boards. This takes most of the "what if" factor away. I did get one channel up and running a couple months ago as mentioned in the K10A thread. It works very well.
The boards with the outputs and drivers mounted on my home made heatsinks:
The raw material for the rest of the chassis:
And the progress I had made initially. The chassis was mostly finished.
I have now committed myself to finishing this amp. In order to persuade myself to spend time in my home office doing business related work (I hate doing
) I have decided that this will be the destination for this amp playing on a new pair of bookshelf speakers (next project).
Up to a few days ago it sat idle, taking up space on a part of my bench.
I needed to finish the power supply. Now, as if it wasn't bad enough that each amp needs two transformers, I went the extra distance to put all of this in it's own enclosure. I thought it would be nice if the amp had an open skeletal look about it. More artsy. Heck the transparent amp will produce that transparent sound 😀
So, I made a sheet metal can to house the power supplies. Two 24 volt, 60VA plus on dual 30 volt 8VA (or so). Bridge rectifiers and to add to the artistic presentation - the smoothing caps peeled and mounted on top:
In this pic, the can is empty. I had the 24 V transformers, but I needed to order the dual from Digikey to get one small enough to fit.
Also seen is one board populated.
Here's how that PS enclosure looks now, earlier today I finished packing the parts in. Making good use of cut up Christmas cards as insulation 🙂
I needed to finish the power supply. Now, as if it wasn't bad enough that each amp needs two transformers, I went the extra distance to put all of this in it's own enclosure. I thought it would be nice if the amp had an open skeletal look about it. More artsy. Heck the transparent amp will produce that transparent sound 😀
So, I made a sheet metal can to house the power supplies. Two 24 volt, 60VA plus on dual 30 volt 8VA (or so). Bridge rectifiers and to add to the artistic presentation - the smoothing caps peeled and mounted on top:
In this pic, the can is empty. I had the 24 V transformers, but I needed to order the dual from Digikey to get one small enough to fit.
Also seen is one board populated.
Here's how that PS enclosure looks now, earlier today I finished packing the parts in. Making good use of cut up Christmas cards as insulation 🙂
I elected to go with just a straight grounded cord instead of the IEC connector. This was mostly to save space and it cleans up the appearance a bit.
The all important chassis ground connection:
Power supplies tested and closed up, ready for action.
Binding posts and RCA's installed:
Still lots of work to do. I finished stuffing the other amp board but haven't tested it yet.
The all important chassis ground connection:
Power supplies tested and closed up, ready for action.
Binding posts and RCA's installed:
Still lots of work to do. I finished stuffing the other amp board but haven't tested it yet.
That's all for today. I have both channels working and tested.
I took the liberty of adding some terminal blocks to the open areas of the boards to allow easier disconnecting for trouble shooting and fixes. I still need to run the input wires from the RCAs to the input terminal blocks and connect the front panel switch but overall, a neat wiring job.
I took the liberty of adding some terminal blocks to the open areas of the boards to allow easier disconnecting for trouble shooting and fixes. I still need to run the input wires from the RCAs to the input terminal blocks and connect the front panel switch but overall, a neat wiring job.
very nice work
very nice work i think .... but also glens pcb is also joy !!!!!
hopefully when ever glen have the time he will also send me a couple of pcb .........
i ve been making like a gozilion amps ...this one is the first that will include a tube .....lets see
very nice work i think .... but also glens pcb is also joy !!!!!
hopefully when ever glen have the time he will also send me a couple of pcb .........
i ve been making like a gozilion amps ...this one is the first that will include a tube .....lets see
Well it certainly looks flash. Have you let is sit for a while to see how hot the heatsinks get?
Cheers,
Glen
Cheers,
Glen
Sakis, I replied to your email, but it bounced:
----- The following addresses had permanent fatal errors -----
<XXXXXXXXX>
(reason: 550 relaying denied for <XXXXXXXXXXXXX>)
----- Transcript of session follows -----
... while talking to mx1.mail.eu.yahoo.com.:
>>> DATA
<<< 550 relaying denied for <XXXXXXXXXXXXXXXX>
550 5.1.1 <XXXXXXXXXXXXX>... User unknown
<<< 504 At least one RCPT command is required
----- The following addresses had permanent fatal errors -----
<XXXXXXXXX>
(reason: 550 relaying denied for <XXXXXXXXXXXXX>)
----- Transcript of session follows -----
... while talking to mx1.mail.eu.yahoo.com.:
>>> DATA
<<< 550 relaying denied for <XXXXXXXXXXXXXXXX>
550 5.1.1 <XXXXXXXXXXXXX>... User unknown
<<< 504 At least one RCPT command is required
glen ....
this has nothing to do with me ....i receive e mails normally but in case you need to get in touch with me you have also
east_electronics@yahoo.gr
service@eastelectronics.gr
info@eastelectronics.gr
devicemanager@eastelectronics.gr
www.eastelectronics.gr
thanks i was actually waiting for the boards or banking information days now
G.Kleinschmidt said:
this has nothing to do with me ....i receive e mails normally but in case you need to get in touch with me you have also
east_electronics@yahoo.gr
service@eastelectronics.gr
info@eastelectronics.gr
devicemanager@eastelectronics.gr
www.eastelectronics.gr
thanks i was actually waiting for the boards or banking information days now
Re: very nice work
Thanks, I think... 🙂
Glen's board is a beaut, for sure. A few less jumpers would have been nice and a place to put a relay to keep the speaker from getting nailed with that brief jolt of 30VDC. 😀
Actually, the relay would need to switch from a dummy load to the speaker load to avoid the 14+ VDC developing in the output cap. I will put a manual switch on the speaker itself to do the same thing.
Thanks Glen,
The whole enclosure is the heatsink. I have screwed on the lid and turned it on:
With each output running at 800mA (200mV across the .25 emitter resistor) for nearly an hour I have 48*C at the top of each output, 46*C at back of the upright part of the mounting angle, 40*C at the outside thickest part of the heatsink and the lid is nicely warmed up to 35*C.
I think this will be fine.
I need to build the front panel power switch and put some feet on it. It has 4 - 5 watt resistors under it now (not in the pics) to allow air circulation underneath.
I'm seeing about 8.5 watts (into 8 ohms) before clipping with my power supply. Clipping starts on the bottom first and looks clean. With the 8 ohm dummy load, I have <5mV offset with the input open.
Looking forward to office work soon! 😉
Hi sakis,sakis said:
Thanks, I think... 🙂
Glen's board is a beaut, for sure. A few less jumpers would have been nice and a place to put a relay to keep the speaker from getting nailed with that brief jolt of 30VDC. 😀
Actually, the relay would need to switch from a dummy load to the speaker load to avoid the 14+ VDC developing in the output cap. I will put a manual switch on the speaker itself to do the same thing.
G.Kleinschmidt said:
Thanks Glen,
The whole enclosure is the heatsink. I have screwed on the lid and turned it on:
With each output running at 800mA (200mV across the .25 emitter resistor) for nearly an hour I have 48*C at the top of each output, 46*C at back of the upright part of the mounting angle, 40*C at the outside thickest part of the heatsink and the lid is nicely warmed up to 35*C.
I think this will be fine.
I need to build the front panel power switch and put some feet on it. It has 4 - 5 watt resistors under it now (not in the pics) to allow air circulation underneath.
I'm seeing about 8.5 watts (into 8 ohms) before clipping with my power supply. Clipping starts on the bottom first and looks clean. With the 8 ohm dummy load, I have <5mV offset with the input open.
Looking forward to office work soon! 😉
I tested the newer amp with a speaker and the turn on thump is nearly non-existent. I don't know why this would be, maybe a difference in tubes? When I tried the first board 2 months ago I used an old and maybe worn out Hitachi Hitray tube that I'd found. I have replaced that with a new Electro Harmonix and the thump on that channel is less pronounced.
I have finished the power switch:
It is the third such switch I have built (the first went on my sub amp and the second on my computer case) and it gets a bit easier with practice. Basically a push button on/off mains rated switch with a box built around it containing 2 LEDs. In this case, high intensity red LEDs. The clear plastic ring illuminates. The switch has a new "button" that fits snuggly inside the ring and is glued to the switch button.
Needless to say, this takes a considerable amount of time but it is exactly what I want.
I have finished the power switch:
It is the third such switch I have built (the first went on my sub amp and the second on my computer case) and it gets a bit easier with practice. Basically a push button on/off mains rated switch with a box built around it containing 2 LEDs. In this case, high intensity red LEDs. The clear plastic ring illuminates. The switch has a new "button" that fits snuggly inside the ring and is glued to the switch button.
Needless to say, this takes a considerable amount of time but it is exactly what I want.
The final push...and I'm done. 🙂
A look at the power switch. Even with two high intensity LEDs, it is a cool muted glow - nothing that's going to grab your attention and hypnotize
And a last look from behind:
Over and out.
A look at the power switch. Even with two high intensity LEDs, it is a cool muted glow - nothing that's going to grab your attention and hypnotize
And a last look from behind:
Over and out.
housing said:
Thank you housing 🙂
Nice to see someone other than me is looking at it 😉
How's your RMI build coming along? Having fun yet? 😀
MJL21193 said:
Hi John,
Got the boards but not yet started working on it. Am still working on the Beta 24 from another forum.
BTW, how does your RMI sound?
😀
That's a work of art, MJL.
What did you use for the illuminated switch ring? I've been thinking of the same idea on an amp I'm building, but couldn't think of a source for the plastic/perspex surround. I'm thinking of a perspex drawer handle or something similar, drilled.
I hope the child you took the Pooh book from doesn't find out!
Cheers
Stu
What did you use for the illuminated switch ring? I've been thinking of the same idea on an amp I'm building, but couldn't think of a source for the plastic/perspex surround. I'm thinking of a perspex drawer handle or something similar, drilled.
I hope the child you took the Pooh book from doesn't find out!
Cheers
Stu
MJL21193 said:
Yes, it is a difference in tubes. It all depends on how one of triode sections warms up with respect to the other. It will probably change over time as the tubes wear out too.
Cheers,
Glen
housing said:
Remember, mine is NOT the RMI, mine is an Abomination!
Sounds spectacular. The best amp I've built so far.
🙂
Stuey said:
Hi Stu,
I briefly demonstrated the construction of the switch here.
I won't lie, it's time consuming and you need to be relatively skilled to have it work out well and look good. That said, it is unique.
G.Kleinschmidt said:
I won't be using this amp much, just when I force myself to do office work, so it may take a while for the tubes to wear out. It's not too big a deal, not like it will blow up the speakers. It's nice when you're showing off the "hi-end" gear and it starts silently though.
I haven't given it a proper listen yet, as I haven't even started the speakers that will be paired with this. I wanted to try a fullrange design (like the Fonken) but the fact is that I have too many drivers sitting around here unused - I'm better off to build with what I have. A pair of Vifa PL18 midwoofs and a pair of 2" cone tweeters that I'll horn load with the solid wood baffle. Not high efficiency, but the office is small and I don't need 120db!
Should be interesting.
MJL21193 said:
John,
you don't happen to have the DK number handy, before i toss myself over the balcony ?
I gave up on finding a chassis mount 30Vac (or twin 15Vac), so anything will do.
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