Took the plunge on power scaling my komet

glogulus

Silver Supporting Member
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1,041
Does anyone have any experience having their komet power scaled? I'm just wondering what my expectations should be.. I hope this works out. From what I have been told, it should help to bring down the volume, without giving up too much tone... Here's to hoping..
 

hamfist

Member
Messages
1,595
I would not do anything to alter the Komet Circuit.
The way it has been explained to me is that the PS is not "in" the circuit. When the PS is turned all the way OFF, then the circuit will merely act as the original non-power-scaled circuit.
Someone please correct me if I am mistaken (wouldn't be the first time !).
Sounds like a great mod for the Komet, to make it much more accessible at less than pounding volumes.
When its all done and dusted, some lower volume clips would be great, just to make us all truly jealous !!
 

Killcrop

Silver Supporting Member
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11,677
I think it's a great idea but you better have a really good tech. The Komet is my favorite amp of all time but the volume killed it for me.

I would have it installed in a pre-existing hole if you can. The PS can be tricky to install in an amp that's not EL84 cathode biased.

See if Hogy will do it.:eek:
 

Steve Dallas

Member
Messages
8,317
I would think very hard about adding PS to a Komet. I'm concerned about what it would do to the resale value (and I'm not totally sure there is room inside that chassis).

In any case, it is true that cathode biased amps are easier to power scale. It is done with a very simple technology generically termed Variable Voltage Regulator and various schematics are everywhere (google it). This has been around practically forever in more and less complex forms, but it was KOC who originally thought to apply it to an amplifier. It works because as you vary the B+ voltage in a cathode biased amp, the bias tracks down automatically.

It is trickier with fixed bias amps. Since the bias is "fixed," it does not track down automatically as the B+ is lowered. This is where KOC comes in. He developed a circuit that will track the bias down as the B+ is lowered, and there is a lot more to it than in the cathode bias version.

You also have to decide how to apply the technology. You can scale the entire amp, just the power amp, or the power amp and PI. Or you can scale the power amp and use power dampening on the PI. If you do the entire amp, you can have a one knob solution. If you do the other variants, you combine a strong preamp with the "weakened" grids of the power tubes, which leads to some pretty ratty sounds. For this, you need "drive compensation" or a good master volume. You set the PS contol to the level you want, then set the master to a point where the amp sounds right.

You also have to decide the limits of how it scales. As in, how quiet do you want it to get? I tend to set mine to cut the volume by 75% and no more. I just don't like how it sounds when you go down to "bedroom" levels. I'd just rather play a small amp. Sure, with lots of tweaking to the PS circuit and the amp itself, you can get it to sound pretty darn good down there, but I find the compromises at high volume are not worth the gains at low volume. The whole system is dynamic, and it takes a while to find the sweet spot for any given amp.

I'm also just a "one knobber." I don't want to have to bend over the amp before the gig and fiddle with 2 or 3 knobs to get the amp to sound right.

Anywho, if you decide to have it done, I echo Killcrop. See if Hogy will do it for you. If it is factory done, maybe that will save the resale value for you.
 

hamfist

Member
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1,595
I think it's a great idea but you better have a really good tech.
Absolutely. I'd make sure it's someone who is on the London Power recommended installers list. Ideally someone who's also been personally recommended to you. Super-ideally, someone who's also had experience power-scaling Komet-like amps.

There ya go. No problem !!
 

glogulus

Silver Supporting Member
Messages
1,041
Sorry for the delay. Travelling to family!

I thought long and hard about this, and I'm having it done by a reputable tech in San Jose (Val@King Amplification). He has done a couple of komets now and from what I've been told they all turned out very well. What's nice about Val is that he is definitely sensitive about modding (drilling holes) the amp, and promised to be real gently like :).

I'm not too worried about resale, as I don't think I will ever sell the amp. I love the way it sounds at 1 on the volume dial. If that's what I have to live with then so be it. It would be nice to see how it sounds turned up with the power scaling.. This will be an interesting experiment. I'll post once it comes back to me, which should be 3 weeks or so. Thanks for everyone's feedback. I was hoping someone who already had this done would chime in, but I guess I am entering uncharted territories..
 

billm408

Member
Messages
3,015
glogulus... I saw your Komet at Val's yesterday (black & green?). Val's actually got three Komets in his shop right now. First time I've seen that many in one place!
 

glogulus

Silver Supporting Member
Messages
1,041
glogulus... I saw your Komet at Val's yesterday (black & green?). Val's actually got three Komets in his shop right now. First time I've seen that many in one place!
Yup, the green and black is mine! I didn't see any other komets when I dropped off mine, but it sounds like a lot of people are getting the same idea. I had Val do a tune up on a marshall for me, and I really liked the service. I do think I am in the right hands. As for how it will sound after he is done, well, we'll just have to see how the amp takes to power scaling.
 

glogulus

Silver Supporting Member
Messages
1,041
I think you're in good hands with Val. He's power scaled 3 of my amps, and one of which the creator seems to vehemently think it ruins the amp, but it made it better. He's one of the good ones when it comes to having power scaling installed in a thoughtful way. He didn't install it the same way in each of my amps - he thinks about what he does, and he has the knowledge to do it right.

And as far as ruining resale, I'd easily pay 300 bucks more than going price for a power scaled Komet.
That's what I like about Val, he told me he would take a look at the amp first, and then come up with some options on how we should proceed to do the mod. Take pictures, etc.. Great guy to work with.

Hehe, so can I hold you to your word if the mod doesn't work out, kidding! :)
 

billm408

Member
Messages
3,015
Yup, the green and black is mine! I didn't see any other komets when I dropped off mine, but it sounds like a lot of people are getting the same idea. I had Val do a tune up on a marshall for me, and I really liked the service. I do think I am in the right hands. As for how it will sound after he is done, well, we'll just have to see how the amp takes to power scaling.
There's two matching black on white heads next to yours that he's modding. You won't be disappointed. Val's a great guy to deal with and is one of the premier PS installers in the country. And he'll work with you to make sure that you're absolutely satisfied with your amp before it leaves his shop. I have one of his amps and two Bogners and Val is the only person I trust to touch my amps.
 

58gasman

Member
Messages
412
Val king of King Amplification has done a power scaling mod to a Komet 60. I did not personally hear the results but I am told that the owner was quite happy.

Give him a call. I am sure he can address any concerns or questions you might have.
 

Kborg

Gold Supporting Member
Messages
585
Please post your opinion of the results and some pics. I have a K60 that I always attenuate and this may be an answer for me.
 

trower

[geer/peyj] hubris, confuse, paralysis by analysis
Gold Supporting Member
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4,577
+1 on Val's work....anybody ever sit in on a Saturday jam outside in the lot?
 




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