Upgrading Klark Teknik Gear

[ef37a]

I do agree with you John about valves not making a huge difference.

A few years ago I was asked to build a switcher that could compare two ECC83 stages instantly in a guitar amplifier circuit. The different brands were compared by some graduate engineers who were also very experienced players. They concluded that there WERE differences, especially as the valve was driven into distortion but they were small.
The object of the exercise was to to decide whether it mattered to the overall sound of an amplifier which brand of valve was bought in. The conclusion was that it did not. In a commercial operation one does not put all one's eggs in one basket!

Regarding the "night and day" claims you mention abound but such 'test' never come with a b&a voltage table let alone a measure of any gain or response changes. A recording of the process has never been seen or heard by this old valve jockey!

Dave.

[GarlandKelley]

I have upgraded both the KT EQP-KT (Pultec copy) and the 76-KT.

My upgrades were capacitor upgrades, both film and electrolytic. All of the components were basically cheap.

I upgraded all electrolytics to Audio grade electrolytics, and film caps to Polypropylene or polystyrene. I did not replace the higher voltage electrolytics. I also replaced the tubes on the EQP with vintage.

I did not replace the Midas transformers.

Does it make a difference? In reality, I did the upgrade immediately after purchase. In my opinion, upgrading capacitors to polypropylene or polystyrene is a well known "immediate" upgrade. Such an upgrade withstands the perils of mix down, and clarity that only seems to really be noticeable when competing with other tracks in the mix for 'audio space'....then the reward becomes more apparent.

These caps don't cost a fortune. replacing the lower voltage electrolytics with audio grade Nichicon or Elma is also not to difficult. But audio caps can be double or triple size of their budget equivalents...so space is of concern. One has to measure the space on the board, the pin spacing. The circuit boards on the KT are not so easy to solder/unsolder imo. Both my units work well now and sound great. I think its particularly important upgrade for the EQP....as EQ is usually dramatically improved with capacitor upgrade.

I keep a list of all the caps, spacing, voltages etc....for anyone who is interested.

Would you mind providing that list?

[ef37a]

There are couple of reasons to change or even increase the value of electrolytic capacitors in the signal path.

1) if the MEASURED LF response does not come up to snuff (that assume of course that you have an original specification!)

2) Electrolytic caps do produce distortion if there is more than about 80mV across them so obviously the problem gets worse the lower you go. You might need a cap' an order bigger than the LF turn over suggests to eliminate that.

Supply filter capacitors are a whole other question. Any properly designed amplifier ( power or op amp) will have a Power Supply Rejection Ratio of at least 100dB and probably better than 120dB. It is hard to see therefore how any supposed shortcoming in standard grade capacitors can get passed into the signal path?

Certainly if cost and space permits fit 105C types. They will then see out almost anyone reading this forum!

Dave.

[dickiefunk]

I have a KT-2a and 76-KT. I did change the optocell for the Kenetek T4b and Harma Retro valves. I found the Kenetek optocell did smooth out the compression a little and the overall sound is a little ‘thicker’ for want of a better word. Also, I noticed there is a small but noticeable reduction in noise with the Harma tubes. Whilst these changes obviously haven’t dramatically transformed the KT-2a, I am satisfied with the small but noticeable improvements made. If I wanted to improve things further and could justify the cost, I would just go for AudioScape or Tegeler. However, at the level I’m working, the KT-2a is working great!
I left the KT-76 stock as it already sounds good to me.

[znjamznjam]

I have upgraded both the KT EQP-KT (Pultec copy) and the 76-KT.

My upgrades were capacitor upgrades, both film and electrolytic. All of the components were basically cheap.

I upgraded all electrolytics to Audio grade electrolytics, and film caps to Polypropylene or polystyrene. I did not replace the higher voltage electrolytics. I also replaced the tubes on the EQP with vintage.

I did not replace the Midas transformers.

Does it make a difference? In reality, I did the upgrade immediately after purchase. In my opinion, upgrading capacitors to polypropylene or polystyrene is a well known "immediate" upgrade. Such an upgrade withstands the perils of mix down, and clarity that only seems to really be noticeable when competing with other tracks in the mix for 'audio space'....then the reward becomes more apparent.

These caps don't cost a fortune. replacing the lower voltage electrolytics with audio grade Nichicon or Elma is also not to difficult. But audio caps can be double or triple size of their budget equivalents...so space is of concern. One has to measure the space on the board, the pin spacing. The circuit boards on the KT are not so easy to solder/unsolder imo. Both my units work well now and sound great. I think its particularly important upgrade for the EQP....as EQ is usually dramatically improved with capacitor upgrade.

I keep a list of all the caps, spacing, voltages etc....for anyone who is interested.

It wil be nice if you can publish list foor eq kt