Klark Teknik EQP-KT - Has anyone modded theirs?

[Tubetec]

I called into a bric a brac shop where the guy has baskets of old style wall warts ,
I grabbed myself a unregulated transformer based 15V dc 800mA adapter ,
Unloaded volts were 18.8 ,
on load with the EQP I measured 15.8v ,
we know the pair of tube heaters want around 150ma each at 12.6V , so the transformer is at around 50% load ,
Its around a volt higher than what the SMPS puts out , but the regulated heater still measured 12.64 V and no problem with the extra heat , never the less attaching a small heatsink to the 317 regulator might be a good idea in the long run .

Just be aware the KT2A runs a hefty 12BH7 , so requires a lot more heater current than the EQP , Id suggest at least double the capacity of what Im using in the EQP .

So I had a closer look at the main PCB on the EQP and I have to say Im impressed .
theres not an SMD component in sight , which really is great news for the Diy'er
The components that are there look like good quality metal film resistors and foil caps ,
electrolytics are the typical Chinese made stuff , but they do at least bear 105c temp ratings .

I found a local source for the dual voltage shaver socket , 11.50 euros in white plastic
The metal clad pattress or back box costs around 5 euros ,
the blanking plate is around 10 euros
Then I added a couple of metal cable glands , with 20mm thread adapters to fit the knock outs in the enclosures ,
mains plug and cable I cut off an old electrical appliance at the recycling centre ,
I have bags of unused 330v/100uF caps from disposable flash cameras , although I think for safety a 450V component is better for first filter ,
A high voltage bridge rectifier and 450v cap can be found in any SMPS
Theres no need for a PCB , a couple of tag strips and hard wire will do ,

I was thinking of using lever terminal blocks to mount the dropper resistors , along with 110/230V secondary selection it makes for a very versatile passive tube pre HT supply .

The two back boxes, one for HT ,one for LT , two blanking plates ,transformers ,other hardware/components and cables this thing amounts to a very tough 2kg all metal lump ,
with excellent magnetic screening , both between the two internal transformers and external equipment .

I checked the spec of the Pultec EQP 1a , noise -89db
The EQP KT claims a noise of -101db ,
Cleaning up the out of band noise might not make a huge difference to the numbers ,as far as 20hz-20khz S/N goes , but it can reduce whats now a sea of modulating fuzz tones , to noise of an entirely random nature which doesnt intermodulate with the audio in anywhere near as destructive a way as cylical noise .

I also found neat touch proof stainless vents for the 20mm knock outs ,
That should allow adequate ventillation so the internal temp in the box doesnt rise and rise over the course of hours ,days, weeks , instead it just comes upto opperating range in under 30 minutes and stays where it is ,just warm to the touch .

The EQP-KT totally neglects air ventillation in the vicinity of the tubes ,
again ,in my opinion thats a mistake under any circumstances as it pushes the time it takes the units internal temperature to stabilise out to hours and hours ,
directing heat from the tubes away from electrolytics is also likely to extend the units life .

 

[Brian Roth]

A slight veer, but it involves Klark Teknik products and heat.

In the 1980's our studio added a KT DN780 digital reverb. It had a small (2"??) exhaust fan at the rear but NO intake vents! After a few years the unit failed. Upon inspection, the power supply PCB was seriously "browned". I forgot what PSU component had failed but I decided to "shotgun" the lytics on that card while I had it apart. It had run so hot the foil on the PCB had delaminated in some areas.

I used my Greenlee XLR chassis punch to knock some holes on the top cover and on the rear of that cover, used some silicone glue to attach a small piece of this as a screen for the holes:

https://www.lowes.com/pd/Spectra-Sp...e-6-in-x-20-ft-Gutter-Guard-Screen/5013013519

One useful side effect was the little fan's noise decreased a lot since it wasn't trying to suck air from an essentially closed box. The only air inlet on the stock design were the SMALL clearances around the front panel pushbuttons, as evidenced by the dust collected around those slots inside the unit.

Now....back to our regularly scheduled program....

Bri

 

[Tubetec]

Good story ,
Yeah trying to pull a vaccum with the fan is already going to draw more current and when the tiny spaces eventually get choked up with dust the situation only worsens , to the point of meltdown in this case !

I have a few chosen pieces of HP and TEK on the bench now , its obvious great care and attention is paid to ventillation , both in tube and transistor units ,
again reaching a stable opperating temp in a defined time period is implicit to the workings of these units . I think the same principles should be applied to audio gear ,as sound changes with temperature.

 

[stylesforfree]

Curious as to what people think about the Klark Teknik EQP vs something like the Lindell PEX or the IGS rubber bands.

I used to have a pair of the PEX I used for a while but they weren't matched so using them in stereo on drums was a pain, individually on hats and snares they were pretty good but I ended up reverting back to plugins.

My friend has a Sound Skulptor EQP501 which is pretty good it has a nice sound, smooth and sweet and they sometimes pop up pre-built.

I might pick up a 500 IGS rubber bands ME but copping a pair of the EQP would save me considerable money. It does feel like there is a fair bit of saturation with the amount of pultec clones out there these days.

Of course going the 500 route means it's gonna be a solid state affair and having never used a real pultec maybe I won't be missing too much?

 

[JMan]

Curious as to what people think about the Klark Teknik EQP vs something like the Lindell PEX or the IGS rubber bands.

...

Of course going the 500 route means it's gonna be a solid state affair and having never used a real pultec maybe I won't be missing too much?

I have two KT EQPs in my rack. They very rarely get used, but then, I have two P2P DIY Pultecs in that same rack, so I tend to favor those. Not hating on the KTs at all, but tbh I'm not convinced they are preferable to a good Pultec plugin, and there are so many of those these days.

Regarding going with the solid state vs tube: although tubes are wonderful and deserve much of the love that is heaped on them, you'll also find folks who prefer a solid state Pultec to its tube counterpart for some things. I'm not saying one opinion or the other is right, but the passive filter section should be identical on both, so it comes down to a question of which flavor of make-up gain you like.