Beautifull work!
But there is one thing I really anal about, I would love to see tubes layout more symmetrical.
I would love it more if the Rec tube were in-between the ptx and choke and caps all lined up.
Just my analness.
But there is one thing I really anal about, I would love to see tubes layout more symmetrical.
I would love it more if the Rec tube were in-between the ptx and choke and caps all lined up.
Just my analness.
I have to ask has anyone had any success putting a 6DJ8 in the driver circuit?? I could change values of resistors ect. to make it work but I wonder how it sounds. Only asking because I have plenty of NOS 6DJ8 and 12AT7 available and would like to use them up😀
Yes
Yes, you can just drop one in and it will work however itis suggested you change the cathode resistor value to half of the 6n1p value...I have done both and was not impressed much by either change...to me, the original circuit sounds best but again, this is very subjective. Start by just swapping the tube then parallel a resistor of the same value to the cathode if you don't like what you hear...IIRC it is 1K and the recommended value for the 6DJ8 is 500-600R....that is IIRC...
Yes, you can just drop one in and it will work however itis suggested you change the cathode resistor value to half of the 6n1p value...I have done both and was not impressed much by either change...to me, the original circuit sounds best but again, this is very subjective. Start by just swapping the tube then parallel a resistor of the same value to the cathode if you don't like what you hear...IIRC it is 1K and the recommended value for the 6DJ8 is 500-600R....that is IIRC...
Thanks JM, I'll have a go. Perhaps also buying some 6n1p tubes might be worthwhile, after all they are pretty cheap. I might even try using both sides of the 6dj8 to drive a single kt88.... now I just got to find some output transformers.😀
Using both sides seems a good idea, it will increase the drive current, but what this design needs is a cathode follower IMO.
Does the main power tube really need that low impedance drive? is there big advantages to this method rather than hanging off the anode? of course I would steer away from pentode drivers in any case, too many pins
I am running 560 ohms on the Cathode of my El34.
I am not sure how you get away with 7.2 ohms there.
Too many pins , and too many resistors, I know... It' s not that scary though if you see that the pentodes are triode connected.
Also, the strange feedback from the OPT secondary is optional too.
Also, the strange feedback from the OPT secondary is optional too.
I wasn't going to say strange, but interesting feedback for sure😀. Kind of reminds me of something out of a mac....
I'll take your word for it as I have no idea who Morgan Jones or his products? are. Time for a google search.....
Anyone have an opinion on [FONT=arial,sans-serif]Transcendar output transformers? I was looking at either the 10W or 15W models they have. The 10W are about $150 the 15W are $200 a pair.....
In single end the KT88 should be happy with 10W but I was thinking of getting the 15W units to allow for some headroom.... anybody have an opinion? unfortunately we get rubbish here in Australia.
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In single end the KT88 should be happy with 10W but I was thinking of getting the 15W units to allow for some headroom.... anybody have an opinion? unfortunately we get rubbish here in Australia.
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This design is simple and sounds great as it is...sure you can do all sorts of different iterations on the driver circuit but until you have built it and listened to it as it is, I wouldn't change a thing...just my two cents from a guy who has built it a few times now....
As far as output transformers go IMHO you can't beat the price and quality of Edcor...they perform way better than they list in the specs....the Mars OPTs are good too...I habe used James as well...my favorite was the Edcor...big and heavy but who cares...it is a tube amp...wasn't meant to be portable.
The beauty of this amp is in it's simplicity and price...for as easy as it is to build and for how cheap you can do it it sounds fantastic...
I have built it with premium parts and average parts and either way it sounded great...I was not a big fan of subbing the 6DJ8 with either cathode value...seemed to suck the life out of it either way....but that's from a guy with badly damaged 43 y/o ears so take it for what it is worth...I do recommend setting it up with a two pole three position rotary switch to enable it to switch between triode, UL, and pentode...if you have UL taps on your OPTs.
Have fun and be sure to post some pics when you have finished it....
As far as output transformers go IMHO you can't beat the price and quality of Edcor...they perform way better than they list in the specs....the Mars OPTs are good too...I habe used James as well...my favorite was the Edcor...big and heavy but who cares...it is a tube amp...wasn't meant to be portable.
The beauty of this amp is in it's simplicity and price...for as easy as it is to build and for how cheap you can do it it sounds fantastic...
I have built it with premium parts and average parts and either way it sounded great...I was not a big fan of subbing the 6DJ8 with either cathode value...seemed to suck the life out of it either way....but that's from a guy with badly damaged 43 y/o ears so take it for what it is worth...I do recommend setting it up with a two pole three position rotary switch to enable it to switch between triode, UL, and pentode...if you have UL taps on your OPTs.
Have fun and be sure to post some pics when you have finished it....
Silly bugger posted in the middle of the quote :
Thanks again JM, I'm currently looking at the edcor CXSE25-8-5K units as I seem to get more bang for my buck, rated at 25 W instead of the transcendars 15 W for about the same money. Might as well get a power transformer off them at the same time...
The XPWR059-120/240 seems suitable...
Thanks again JM, I'm currently looking at the edcor CXSE25-8-5K units as I seem to get more bang for my buck, rated at 25 W instead of the transcendars 15 W for about the same money. Might as well get a power transformer off them at the same time...
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