missi93

Re: G-PULTEC problems, please help!
« Reply #780 on: September 01, 2020, 07:38:44 AM »
Here is a Screenshot from a Real Time Analyzation with a 11dBu 1kHz signal going through the G-Pultec



missi93

Re: G-PULTEC problems, please help!
« Reply #781 on: September 01, 2020, 07:40:31 AM »
and another one , same signal , same level going through the Pulse Techniques.

Some impressive numbers.

Thanks for your time guys,
let me know what you think!

M.

missi93

Re: G-PULTEC problems, please help!
« Reply #782 on: September 01, 2020, 11:59:30 AM »
Hey again,

I still have one problem. After seeing the tube main voltage at 360V ! I upped the 2W resistor to 5,6k first and then 10k and now it's sitting around 280V. Is it still too high?

Isn't there a end point where it stops making sense to put higher resistors?
Or should I just go higher Ω until I reach the 250V recommended?

M.

gyraf

Re: G-PULTEC problems, please help!
« Reply #783 on: September 01, 2020, 02:28:09 PM »
That's an awfully high voltage - is your transformer correct type?

But yes, definitely best to be below 250V - that way your tube has a better chance of having a decently long life..

/Jakob E.
..note to self: don't let Harman run your company..

missi93

Re: G-PULTEC problems, please help!
« Reply #784 on: September 03, 2020, 08:32:30 AM »
Yes the values should be right, it is the Mono G-Pultec Transformer from Don' Audio with a 220V secondary.

I don't get why it outputs 300 or more.

I will make another overview soon, and see how much exactly I am getting from the transformer.

M.

Re: G-PULTEC problems, please help!
« Reply #785 on: September 14, 2020, 02:33:54 PM »
Yes the values should be right, it is the Mono G-Pultec Transformer from Don' Audio with a 220V secondary.

I don't get why it outputs 300 or more.

I will make another overview soon, and see how much exactly I am getting from the transformer.

M.

220VAC rectified = about 305VDC

Measure the AC off the trafo before connecting to the circuit - might give you a clue.

Gustav

Whoops

Re: G-PULTEC problems, please help!
« Reply #786 on: October 06, 2020, 01:21:57 PM »
I'm cleaning my workshop and found 2x G-Pultec pcb sets
I put the set for sale in the black market in case someone is interested:

https://groupdiy.com/index.php?topic=76070.0

innercityman

Stereo G-PULTEC in One case
« Reply #787 on: January 21, 2021, 01:10:47 PM »
Hi guys,

I'd like to built a stereo unit in one case and I'd like that only one knob, pot, switch, controls both sides... Do you think it's possible to do that ? How difficult would it be ? Does every component from one side to the other has to be matched ?

innercityman

Stereo G-PULTEC in One case
« Reply #788 on: Today at 04:28:22 AM »
Ok, maybe stupid question. Anyway...

Could it be as simple as using 2 G-Pultec PCB kits and using dual gang potentiometers and dual gang rotary switches to control both channels with knob ?

gyraf

Re: G-PULTEC problems, please help!
« Reply #789 on: Today at 07:49:29 AM »
Yes, you could do that - but you'd need to select your tubes, inductors, capacitors and possibly resistors in order to get decent tracking between channels. These mentioned in order of importance.

Specially the high-boost inductors AND capacitors used there need very high precision in order to not get annoying at high Q's (for my G14 I aim for 0.3% on both inductor and capacitor).

Note, on the other hand, that the absolute values are not all that important, so you can just buy a big handful of parts and match from there..

/Jakob E.
..note to self: don't let Harman run your company..


Whoops

Re: Stereo G-PULTEC in One case
« Reply #790 on: Today at 08:31:09 AM »
Could it be as simple as using 2 G-Pultec PCB kits and using dual gang potentiometers
[/quote]

You could use Dual Gand Pots, but be aware that potentiometers have a tolerance of 15% to 35% (more or less) depending on brand and type, that tolerance will also apply to individual tapers inside a dual pot. So A dual 50K pot, can have one gang at 47K and the other at 52K, having the different values in the middle point.

Or you are able to get Dual Gang pots with tighter tolerances, probably more expensive, or you buy a lot of them and measure to select the ones were the gangs are closer in value.
Or you replace the Pots with Dual Gang Switches and use 1% metal film resistors

innercityman

Re: Stereo G-PULTEC in One case New
« Reply #791 on: Today at 09:49:02 AM »
Very interesting informations...

Quote
Or you replace the Pots with Dual Gang Switches and use 1% metal film resistors

That would be a too much expensive option I guess.

Quote
Note, on the other hand, that the absolute values are not all that important, so you can just buy a big handful of parts and match from there..

That seems the better option and probably my choice.

I still have a question... Does the components quality especially caps, has an influence on audio quality of this design ? I mean, buying expensive caps like Mundorf supreme line or so worths it or not ?


 

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