Upgrading Klark Teknik Gear

[Arpangel]

Yes that’s all great capacitor information and advice but should I replace the water pump?

No.

[Drew Stephenson]

Only if you can find a manual one or one without any digital controls.

[ef37a]

Yes that’s all great capacitor information and advice but should I replace the water pump?

Yes! And preferably one made of Unobtanium.

Dave.

[Arpangel]

The only way you could improve that amp is to throw it in the bin, that was a shocker of an amp. It looked good, appealed to the aesthetics of the time, and was hyped in the hi-fi press, sorry to be Mr What Hi-Fi, it’s not good! But it is true, a friend had one of those Amd had to get rid of it after a couple of weeks because it was so bad.

Whereas I still have a 3020 and a 3120 and still rather like them. Actually they're remarkably good for what they cost and, as they're both still working around 40 years after I got them - not even a scratchy pot or switch between them, I have no complaints. Also got a 3020e somewhere that still works fine. Haven't changed any bits in them though; never saw the point as they seem to work nicely as they are.

Same as anything like this, depends what you use it with, but if you pair it with unsuitable stuff, it equals disaster, for me anyway.

[Hugh Robjohns]

The only way you could improve that amp is to throw it in the bin...

For the casual passer-by who may be unaware... we established long ago that Arpangel's views on almost everything are so wide of reality that it's positively entertaining....

Amusingly, I still have my old NAD3020 too...

[Hugh Robjohns]

... if you pair it with unsuitable stuff, it equals disaster, for me anyway.

Er... yes...

[knave101]

ALCON,
I have not measured the distortion before the mod....and I may be deluded...but it's my delusion, and I'm sticking to it. What else am I going to do....being single and living in a foreign country! I am stationed in Europe...and with every military move, leave more stuff behind....including what little test gear I have, but I hope to reform my test gear in one site... one day. I see we morphed to a expresso machine mod....which is another of my follies as well. Espresso is a true art.....

I have been engaging in "espresso diplomacy" for some time. It seems to have served my military career well.

[Kwackman]

we established long ago that Arpangel's views on almost everything are so wide of reality that it's positively entertaining....

Arp should use this as his signature!

[Drew Stephenson]

which is another of my follies as well. Espresso is a true art.....

I have been engaging in "espresso diplomacy" for some time. It seems to have served my military career well.

Music is just a hobby/passtime/career*, coffee is life.

* delete or enhance as applicable.

[Martin Walker]

I have not measured the distortion before the mod....and I may be deluded...but it's my delusion, and I'm sticking to it.

Hi knave101, and a welcome to the SOS Forums from me!

I've long been fascinated with this 'modding' business, and there are various well-regarded companies doing this as a business, Black Lion Audio probably being the most famous (their Standard Mods seems to involve replacing opamps, while the Premium Mods are the ones where 'audiophile grade' capacitors and extra IC decoupling enters the picture).

However, I have yet to stumble across any private individual who has recorded before and after audio to illustrate such obvious improvements. Please correct me if I'm wrong as I'd love to listen to some.

Measurements are all very well (and vital in many situations, especially to demonstrate what audio aspect has improved, or at least changed (let's face it, sometimes slightly increasing distortion levels below 50Hz when driven hard can be preferred, which is why certain input/output transformers are so prized for their character).

However, if the improvements with a particular mod are as audible as a modder makes out then they ought to be audible to one and all with a suitable input signal.

Martin

[Arpangel]

For the casual passer-by who may be unaware... we established long ago that Arpangel's views on almost everything are so wide of reality that it's positively entertaining....

What’s reallity?

[knave101]

Martin,
Thank you for the note, and thanks for having me.

I have two KT-76...one is modded and the other is not. I will try to do a side by side in the near future. I only have one EQP, so I can't do it with that, but the EQP would likely be easier to hear as it is an EQ. My mods are typically with WIMA polypropylene caps, polystyrene for the small values, and Nichicon and Elma Audio grade low voltage EL capacitors. I have a couple new mics (Rode TF5) to test out, so that will give me something to do.
There is so much written about the audio capabilities of capacitors now such as http://aeaaudio.com/audiophile-quality- ... le-re-cap/
that it seems an easy mod to do and not to worry too much about whether it changes anything or not. I enjoy doing it.

I don't have the equipment at this time to do an accurate analysis. In past life, I remember in the early 80's at my engineering school, I was studying acoustics and wave analysis, and we had both a regular, walk on chicken wire, and underwater anechoic chambers and all the test gear. It was wonderful! Now I just have my aging ears, not helped by playing in a band for years.

I agree with you on the distortion being sometimes a positive thing, especially in that low mid freq range....it's likely why most of us love transformers, and the go back and forth over the various characteristicss of various magnetic materials such as Alnico II-VI or Cunife, Nickel vs steel, Faraday's law, which "vintage reissue" guitar pickups to get, and why having good transformers is one of the most critical components of any audio device. But the 'transform' is the key...with capacitors too.

Interestingly, the mod I find of lowest value is changing tubes. I'm sure others will disagree. I have boxes of vintage tubes I started collecting in the 80's, and I never find the "night and day" difference that other speak of when they tube roll. But I do notice, especially with polystyrene, a clarity and air of the top end, especially when pushing 'treble' eq, that wasn't prior before.

I'll try to do that KT-76 comparison and get back to you.
john

[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

[joromusico]

2a kt or kt2a whatever….
i waited a year to get this due to backorder.
paid 299.00 for new in 2021.
my plan due to dirt cheap price has been to remove cover and start rolling tubes as they say. Tubes are so cool and mysterious and so fun to learn about as a hobby. Not sure if I will ever understand what is happening with any electronics as engineers do but I heard a story where Robert Moog had such a mind for circuits and sound that he could imagine a sound in his head while simultaneously seeing the circuit that could produce it. So…. this is and isn’t about physics and taste.
I have been lucky to have an associate who is waayyy into tubes and has great testers and about 50,000 nos and vintage tubes stacked on dusty shelves. Hence, i am swapping and listening. I hope maybe interest encourages me to do audio comparison samples but for now the report is the stock tubes are clearly visibly inferior and the pins are so easy to bend compared to the nos tubes i got a hold of to try. The build quality, randomness of getter, and plate texture are different visually. The old tubes feeling more handmade than machine produced, glowing up slower and more amber fiery….After inserting a 60’s telefunken 12ax7 in the port closest to the transformer the difference was marked. The tube was used in hospital lab testing equipment and marked as a “selected tube” supposedly due to its very low noise characteristics. Here’s where objectivity can cloud the mind who has just laid out 150 for a single tube. these are on loan to me so i’m not trying to sell anything to myself.
first, compression engaged sooner at lower reduction settings. upon cranking full output level the nos is substantially quieter than stock. The sound feels more soft and round if that makes sense. In any case it has altered the sound in a way that may achieve any given desired outcome from a performance. Therefore I find it super fun to swap and light these critters up… a weird connection and satisfaction settles over a room and a voice freed up for infinite resolution always constructed artificially in the digital domain.

I think changing tubes does make difference in how this compressor behaves and sounds but there are 4 tubes in this unit and so much experimenting awaits. Also, dirty secret is have fun and any reliably tested vintage tube, nos or not that can be returned if it sucks is worth having a listen. That is if you have time and care enough about sound.

[knave101]

I'd be interested to know where 'knave101' is based...

My observations are that modding/"upgrading" gear - esp mics - is much more prevalent in the US than the UK...

Mike,
Sorry for the delay...a couple years! I am US Military, when I wrote that I was based in Spain. Now I'm in Bahrain. One of the greatest benefits of being overseas US military is getting US parts, gear, etc....shipping via USPS (US mail) anywhere in the world, same price as US and tax free.

I'll addendum my previous posts. As I have pointed out. I have no way of testing the basic design of the cheaper units from KT or Warm vs Originals...and who says the originals are the greatest? Parts in the 60's were likely much worse than now, except for tubes and transformers.

But manufacturers shave pennies by using parts that work, but maybe are not the best. You can put in Wima PP caps for nothing. So long as voltages match or are exceeded, pin space, and pin thickness is taken into account, and the space is there for the size difference. One thing I notice a lot is how small the cheap parts are compared to the "audio grade" Nichicon KZ or Gold caps are.

[knave101]

-76- Parts
Electrolytics on Main Board
47uf 50v (1)
100uf 16v (1)
100uf 50v (2)
47uf 25v (1)
220uf 35v (1)
100uf 25v (1)

Film

154j63 (3) 0.15uf 63v
224j63 (1) 0.22uf 63v
472j63 (1) 4700pf 63v
274j100 (1) 0.27uf 100v (I could not find this available, so I bypassed with polyethylene of much lower value.

Power Supply Electrolytics: 20mm (interference space available)
10uf 50v (2)
47uf 25v (1)
470uf 25 (1)
470uf 35 (1)

[ajay_m]

I think this is just a universal human impulse. One of my interests is 3d printing. There are broadly two groups of people in that sphere. One group just gets on using stock low-cost printers to print stuff. They know that if you set up and maintain these units properly they'll work fine. The second group are endlessly tinkering with new extruders, hot ends, ruby tipped nozzles and so on. It's the tinkering they love. Same here I think. It may or may not sound better but the satisfaction of tinkering with it meets some primeval human need I think.

[Arpangel]

tinkering with it meets some primeval human need I think.

I do believe they discovered a cave drawing in the Australian Outback, of a man re-capping a Neve Console.