diytube.com

Could you zip and attach the PSU file?

Shannon

Here is the zip file with the < KT120_700VCT_V2.PSU >

Hope this works

Dieter

Dieter, is this a transformer that you have on hand or are you planning to get more out of the power tubes? If you have another option, it might be easier to go with a closer to 600VCT transformer. With the PSUDII, I can get good ripple with the small input cap and two small chokes, but C1-C3 need to be at least 500V (more difficult). I adjusted the input cap to 4.7uF and a 630V rated one might be best and it will need to be able to handle high current. I left the DCR of the chokes as you had them, fwiw.

Shannon

Shannon,

first of thanks for the PSUDII simulation, I am still a little confused as to the use of this program, getting closer to understanding it.

At present I am running the Clementine amp with KT88 in triode mode with a 600vct PT, sounding absolutely excellent.

The only reason for the higher 700vct PT is to run the KT120 in a more optimized triode mode giving higher power in the range of 8-10
watts, just like the look of the big tube and was interested to build a new amp with this tube.

As for more power it is easy with your board to run in Ultra mode giving approx double the power in the range of 7-10 watts just adding
depending on what output tubes are being used, a 1k resistor to R27-R28 and remove R15-R16 triode connection, which is well thought
out and agree with the need for loop feedback in Ultra mode because of speaker damping factor which other designs by other people
seem to ignore, having experience with a SE KT88 pentode amp which was run in triode and pentode, pentode without feedback was
not good, very good in triode, your 2 stage design is much better, congrats for that.

Attached find my 600vct PDUDII simulation based on your 700vct simulation using the additional currrent sink, which I did not use before
but now understand why it is there, simulation seems to look good, actual measurements on the KT88 plate show 368v and all
heater voltages are right on have not checked the plate voltages on the 6sl7, which I understand should be around 300v.

Dieter

Shannon

In the previous message I was mentioning about the Ultra linear connection which I thing was wrong, not sure, I am a little confused as to the Ultra linear connection,
coming from the OT to J10,J11 which is connected to R27,R28 the loop feedback resistor?? which would be 1K or 1.2K and can have a 0.0033nF bypass cap is this correct??.

As to the connection to the UL tap on the OT from the board, is this a straight connection from J3,J4 without a resistor and bypass cap??.

Dieter

Dieter, maybe this thread will answer your questions:
viewtopic.php?t=5011
It seems that this is the only ULtra documentation I have done. I need to add it to the main doc page.

Shannon

:))Thanks for your reply

The picture I send was a mistake pushing the wrong button is showing my old setup using a 2a3 PP class A and a KT88 set amp. I do not have the 2a3 amp any more.
I was going to make a new picture showing the new Clementine and my present speaker setup which is still the same, the speakers are 6.5" fullrange rivers, the speaker
cabinets were designed to take care of the baffle step issue acoustically instead of electronics in the signal pass.

Shannon, have you had any experience using Nichicon 100uF 500v 22x40mm electro's, would like to to use these in the 700VCT power supply for the KT120''s
are these ok on your board.

Those should fit fine, and I like Nichicons. Just make sure you have plenty of chassis space - like a 3" tall chassis.

Shannon

Shannon,
Yes the chassis is 3 " high and thanks

Shannon,
Using the Ultra connection with a 1K resistor gives about approx 6 db of feedback ??, for 3 db feedback what value of resistor is needed? so as not
to loose as much gain to try, so an Ipod can be used, which is ok in triode mode.
Dieter

Just go to a 2K (three times the original 680) and measure your damping factor due to higher amplifier impedance. It might be OK, i.e. give you the right amount of gain & damping factor.

Shannon

HELLO, I'M NEW TO THIS,I'M BUILDING A CLEMENTINE FOR KT120'S. AFTER READING YOUR POSTS FOR AWHILE. I HAVE AN OLD 700VCT TRANS. WENT FOR THE 800 OHM CATHODE RESISTORS AND A 3.5K OPT TRANS.MY PROBLEM IS THAT I HAVE 468V AT B+ AND 460V AT PIN 3 &4 ON V2 & V3 AND ALSO I GET 420V ON PIN 2&5 ON THE V1. I DON'T KNOW IF THIS WILL WORK. CAN ANYONE HELP???

Hi and welcome!

A KT88 is likely to be even dare I say "bored" at those voltages

I'll let the Clemintine pros respond to any other concerns regarding this

(P.S.: Unless a disability requires it, posting in all caps is considered "shouting" and rude)

Cheers!