6N2P-EV
@vrun:
I think the 6N2P-EV will be ok, the specs are really quite comparable. Maybe you will have to adjust the CCS current a little.
- Klaus
@vrun:
I think the 6N2P-EV will be ok, the specs are really quite comparable. Maybe you will have to adjust the CCS current a little.
- Klaus
vrun said:
Guess nobody is in a real rush here - go take a nap
"lost sleep" may be counted as a "loss" too
Just as a note...
I do not have tubes in any of my drawers so I intend to use:
6N2P-EV
a russian dual triode very suitable for audio use, similar to the 12AX7/ECC83,
compatible except for the filament.
The tube is heated with 6.3V/340mA via pin 4/5,
pin 9 is connected to a screen between the two triodes and must be grounded.
...can any tube-guy please comment on that??? (I don't mind a little pcb modding myself)
Also I found a single "M 114/40 Armco Quality" Transformer:
sec.
2 x 28V/4A,
6,3V/2,5A,
35V/1A
...surplus=cheap...would solve heating nicely - are the overvoltages within reason? 🙄
That tube should work fine in the circuit without any board modifications (so long as the one you have isn’t worn out 😉 ). The pin-outs are the same. The only thing you will need is a 6.3 V heater supply instead.
The circuits tail current is 2mA. According to the curves for that valve, that will give you a negative grid voltage (WRT cathode) of a little less than -1V. This is a very comfortable operating point, so it needn’t be changed.
The K10A’s circuit topology presents a rather light load (and current swing demand) to the valve LTP, so distortion generated here is very low.
The amp will still work fine with the higher rail voltages provided by that transformer, with a slightly higher power output.
Just make sure you use at least a 1/2W metal film resistor for R10. Q7’s dissipation will rise to about 200mW, but this is still OK for a TO-92 (which is rated at 625mW at Tambient=25 degC).
Cheers,
Glen
EDIT:
WRT to board modifications, a link from pin 9 to ground will be required for the 6n2p-ev.
Boards
Guys, thanks for the prompt payments.
I will send out the first batch of boards on Monday (that's as early as i can do it. Delivery from then will be 4-5 working days).
By then I should have a major webpage update done, including measurements and construction/wiring recommendations (Chassis install is 80% complete)
Cheers,
Glen
Guys, thanks for the prompt payments.
I will send out the first batch of boards on Monday (that's as early as i can do it. Delivery from then will be 4-5 working days).
By then I should have a major webpage update done, including measurements and construction/wiring recommendations (Chassis install is 80% complete)
Cheers,
Glen
Hi Glen.
Thanks for the update, keep up the good work.
Look forward to boards next week and your web page update.
Cheers
Gary..
😀
Thanks for the update, keep up the good work.
Look forward to boards next week and your web page update.
Cheers
Gary..
😀
Thanks Klaus and Glen,
I am going to use 6N2P-EV with no other mod than adding the gnd shield to pin 9 and using 6.3V heating then.
Regards
I am going to use 6N2P-EV with no other mod than adding the gnd shield to pin 9 and using 6.3V heating then.
Regards
Hold up with Canadian and American orders
Hi guys - an update on the shipping of the PCB’s
When I bought those padded envelopes and inquired as to the most economical form of trackable international shipping, I was informed that the envelopes are well under the size and weight definitions of a “parcel”, so they qualify as “letters”.
The Express Post International letter service at $11.85 was quoted.
Unfortunately, when I went into the post office on Thursday (on the way out on a ~1000km by road work field trip) to post the first batch of boards, I was informed that while each envelope qualifies as a “letter” in both size and weight, it does not by content (PCB’s). The Express Post International service therefore incurs additional fees, the total fee going from a reasonable $11.85 to a ridiculous $45 - $50 !
I am currently sending all orders by insured Air Mail instead. The standard (uninsured) Air Mail service is cheap, but offers no traceability whatsoever, giving me no way of providing evidence that I have sent goods for which I have received money. I am not willing to do this with international orders.
So, I am sending goods via Air Mail with insurance, but due to the added fees I am loosing a few dollars with each order, so I am not taking further PCB orders until the current paid-for batch are sent, so I can tally up my losses and increase the individual board price by a dollar or so to compensate.
However, there is a further hiccup with orders from Canada and America. To these two countries Australia Post offers NO insurance on goods (regardless of value) sent via Air Mail whatsoever – meaning not tracking number and no proof of goods sent. I don’t know why this ridiculous situation exists, but is does.
The $45-$50 Express Post International service fee is totally uneconomical, so I will have to find an independent courier company to send the goods at a reasonable fee instead.
All others orders will be send on Monday. Tracking number receipts will be emailed Monday evening.
I also hope to have the Canadian and American orders sorted out as well – will update ASAP
Cheers,
Glen
Hi guys - an update on the shipping of the PCB’s
When I bought those padded envelopes and inquired as to the most economical form of trackable international shipping, I was informed that the envelopes are well under the size and weight definitions of a “parcel”, so they qualify as “letters”.
The Express Post International letter service at $11.85 was quoted.
Unfortunately, when I went into the post office on Thursday (on the way out on a ~1000km by road work field trip) to post the first batch of boards, I was informed that while each envelope qualifies as a “letter” in both size and weight, it does not by content (PCB’s). The Express Post International service therefore incurs additional fees, the total fee going from a reasonable $11.85 to a ridiculous $45 - $50 !
I am currently sending all orders by insured Air Mail instead. The standard (uninsured) Air Mail service is cheap, but offers no traceability whatsoever, giving me no way of providing evidence that I have sent goods for which I have received money. I am not willing to do this with international orders.
So, I am sending goods via Air Mail with insurance, but due to the added fees I am loosing a few dollars with each order, so I am not taking further PCB orders until the current paid-for batch are sent, so I can tally up my losses and increase the individual board price by a dollar or so to compensate.
However, there is a further hiccup with orders from Canada and America. To these two countries Australia Post offers NO insurance on goods (regardless of value) sent via Air Mail whatsoever – meaning not tracking number and no proof of goods sent. I don’t know why this ridiculous situation exists, but is does.
The $45-$50 Express Post International service fee is totally uneconomical, so I will have to find an independent courier company to send the goods at a reasonable fee instead.
All others orders will be send on Monday. Tracking number receipts will be emailed Monday evening.
I also hope to have the Canadian and American orders sorted out as well – will update ASAP
Cheers,
Glen
Hi Glen,
Don't get stressed. Just send mine the cheapest way and hang the tracking and insurance.
I trust you.
Don't get stressed. Just send mine the cheapest way and hang the tracking and insurance.
I trust you.
G.Kleinschmidt said:
Looks good. I have some tubes on the way, just cheap Electro-Harmonix.
Don't worry much about this Glen, or it will take the shine off. I order stuff from all over, and not once has it not arrived. Tied up at customs yes, but that typical.
I had to pull the trigger on that Digikey order, so hopefully your schematic component values (for resistors) didn't change much.
Otherwise, just another excuse for me to make another parts order
I'm happy with mine just going into regular mail--it works 99% of the time. I'm not worried about a tracking number and I won't blame you if they don't show up.
Steve
Steve
Glen,
Same with me - I trust you 😀 😉
I'll take the risk - any "insurance" exceeding the cost of goods really isn't worth a thought.
YOU please enjoy the weekend (and our new amp 😎 )
Same with me - I trust you 😀 😉
I'll take the risk - any "insurance" exceeding the cost of goods really isn't worth a thought.
YOU please enjoy the weekend (and our new amp 😎 )
OK guys, I’ve got some scheduled maintenance to do on my car and a lunch do to attend, but I have set the amp up on the test bench this morning and ran a quick stability test – severe overdrive/clipping with no load attached.
Attached below is the scope shot of the unloaded 20kHz sinewave clipping waveform, waveform probed from before the output coupling capacitor. Vertical scale is 10V/div.
As you can see, no problems with overdrive recovery or stability here 🙂
This is a nice confirmation of something I was trying to get across in another thread about the effectiveness and liberties that can be taken with the type and loacation of output Zobel / load coupling network in designs using low fT BJT outputs.
A slight asymmetry to the clipped sinewave can be seen. This is caused by the fact that I have set the (heavily filtered) DC operating point of the amplifier to a little less than half the supply rail.
This is done because once the amp is connected to a load and actually delivering power, the supply rail will actually sag a little.
Cheers,
Glen
Attached below is the scope shot of the unloaded 20kHz sinewave clipping waveform, waveform probed from before the output coupling capacitor. Vertical scale is 10V/div.
As you can see, no problems with overdrive recovery or stability here 🙂
This is a nice confirmation of something I was trying to get across in another thread about the effectiveness and liberties that can be taken with the type and loacation of output Zobel / load coupling network in designs using low fT BJT outputs.
A slight asymmetry to the clipped sinewave can be seen. This is caused by the fact that I have set the (heavily filtered) DC operating point of the amplifier to a little less than half the supply rail.
This is done because once the amp is connected to a load and actually delivering power, the supply rail will actually sag a little.
Cheers,
Glen
Attachments
Finally, a 10kHz squarewave driving 4 ohms in parallel with 1uF.
The amp is unconditionally stable. The ringing is at the series resonant frequency of the output coupling inductor and the 1uF shunt cap + the 100n hybrid Zobel cap across the speaker terminals = 1/(2pi*(SQR(L*C))) = ~152kHz.
All squarewave testing was done without the input signal bandwidth limited and a 100pF Cdom capacitor.
The amp is unconditionally stable. The ringing is at the series resonant frequency of the output coupling inductor and the 1uF shunt cap + the 100n hybrid Zobel cap across the speaker terminals = 1/(2pi*(SQR(L*C))) = ~152kHz.
All squarewave testing was done without the input signal bandwidth limited and a 100pF Cdom capacitor.
Attachments
MJL21193 said:I had to pull the trigger on that Digikey order, so hopefully your schematic component values (for resistors) didn't change much.
Otherwise, just another excuse for me to make another parts order
Schematic and webpage finally updated and BOM added. I've been listening to the amp for hours now - sounds sweet 🙂
AC/DC's 'Given The Dog A Bone' playing ATM........
Sorry for the delay with the parts list, but there really wasn't much I could do stuck 500km from home on Friday and 200km of dirt road and goat track from the nearest tuck shop 🙂
I designed a high resolution 24-bit temperature / natural gamma radiation bore hole logging probe for my employer, and with geothermal energy being the next big thing, there are all these observation bores being drilled in the middle of nowhere, requiring accurate temperature profiling to keep us busy.
Anyway, the link again:
http://users.picknowl.com.au/~glenk/K10A.HTM
Attachments
Good image Glen. Just colour the sky red and it could be Mars.
Kind of reminds me of South West Africa, only you also need to remove the plants.
Kind of reminds me of South West Africa, only you also need to remove the plants.
Hi Glen
Just payed the PCB's. 😎
As you've said the amp is already sounding sweet ... nice 🙂
Can you please make some measurements like distortion, output resistance, power BW, slew rate ... 😉 Thanks
Just payed the PCB's. 😎
As you've said the amp is already sounding sweet ... nice 🙂
Can you please make some measurements like distortion, output resistance, power BW, slew rate ... 😉 Thanks
OKKKKKAAYYYYYYY..........
Since there seems to be a general consensus that I'm being paranoid about the letter tracking thing, I just posted all remaining orders today via standard Air Mail.
GaryS, Jacco and Radioman63 had their boards sent last Thursday (I e-mailed confirmations)
Attached below is my evidence! LOL!
Most should have their boards in 7 working days.
As can be seen, the basic Air Mail fees are less than what I charged, so I'll Paypal refunds this evening.
4fun, I'll send you a PayPal invoice ASAP.
Cheers,
Glen
Since there seems to be a general consensus that I'm being paranoid about the letter tracking thing, I just posted all remaining orders today via standard Air Mail.
GaryS, Jacco and Radioman63 had their boards sent last Thursday (I e-mailed confirmations)
Attached below is my evidence! LOL!
Most should have their boards in 7 working days.
As can be seen, the basic Air Mail fees are less than what I charged, so I'll Paypal refunds this evening.
4fun, I'll send you a PayPal invoice ASAP.
Cheers,
Glen
Attachments
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