Also read on the Gon that Dan d’Agostino has voiced the sound of the FPB amp series by operating them at 220 VAC.
I currently own a pair of Krell FPB-350 MCX monoblocks which operate on 120 VAC dedicated circuits (14 gauge wire). Contacted Krell and they indicated dip switch positions for operating the amps on 220 VAC. The MBL paper suggests to wire 220 VAC dedicated circuit using 10 gauge wire to reduce electrical noise and amplifier modulation of electrical circuit.
While the theory seem to be valid and before rewiring my dedicated circuits, I would like to have some Krell amp owners comment on the benefit of going to 220 VAC operation for those who have performed the mod.
Being an electronics engineer affords you the ability to experiment in ways others can't.
Special thanks to Mr. Bresnahan from Krell who was very supportive in answering these issues.
As we know, Patrick is one of the good guys; left from the old D'Agostino regime.Always helpful and knowledgeable.
In talking with him in the past, I have tried to Imagine what was going through his head, when he saw the new regime, toss D'Agostino intellectual property into trash bins.
If anyone has ever contacted Krell looking for KBX Crossover Cards, or other similar parts... and they tell you ...sorry ...we don't have any in stock. ........take a guess why :^(
Readers don' t need to take my word. Ask Patrick direct.
I have configured the Krell amps for 240 VAC operation but unfortunately the left monoblock amp did not have its stanby LED lit upon initial powering, while the right amp was behaving correctly. Krell amps have a breaker in the back to power the unit in stanby mode. If you want to listen to your system, you then need to power the front button. I did not push the front power button of the left monoblock to avoid potential disaster.
I had exactly 243 VAC at the output of both power cables. 240 VAC was entering both amps. Reconfigured power dip switches and put the power back to 120 VAC and both amps were working fine. Reconfigured for an operation to 240 VAC and still have the same issue on the left monoblock. Tried to power the left monoblock using the right channel dedicated power circuit and still had the same issue. In all likeliness, I have an amp which will not power up at 240 V...
Put everything back to 120 V and I can notice the improvements feeding power to the amps using 10 gauge wiring. First, the bass is massive compared to my original setup using 14 gauge. There is a level of noise/grunge which was previously unoticable on original setup that is now gone with newer setup. I also noticed an increase of ´thereness’. Recordings with massive orchestration have better instrument deliniation. Soundstage has expanded in width and depth.
Overall I am very happy with the end results using dedicted circuits with 10 gauge/120 VAC and could happily live with it, but somewhat disappointed that one of the Krell is not working at 240 VAC...I will contact Krell to do some basic troubleshooting and see if we can get things going. My guess is that there an issue with the power up/processing board at 240 VAC.
Just finished installing the 10 gauge dedicated circuits. This wire is a bear to work with. I used a core solid copper NMWU 10/2 (black sheeted cable). This cable is so stiff that it was trying to get out of the Furutech GTX-D (R) wire clamping system, when pulling/pushing the receptacle into the receptacle electrical box. Good thing I replaced the 2.5 inch receptacle electrical box for 3 inchers to allow proper wire slack length. Working on the main electrical panel was a breeze. I had my 240 VAC at the receptacles by the end of the day.
Today, I will need to modify the Krell for 240 VAC operation, cleanup the room and sit down with a nice cold beer. I will keep you posted on the results of all this work.
Contacted Krell again and the setting for 240 VAC is 222. Thank you msalvatore for pointing out your settings. These seems to be specific settings for 220 VAC and 240 VAC. I initially asked the wrong voltage setting to Krell (220VAC). Special thanks to Mr. Bresnahan from Krell who was very supportive in answering these issues.
Thank msalvatore for your input. Did you run your amps on 120 VAC/60 Hz initially? What were the improvements moving from 120 VAC to 240 VAC? Also you indicate that your switch configuration was 222. On which model of Krell amps?
I have contacted Krell and they say my switch combination is 122 for 220 VAC (previously was 212 for 120 VAC).
I have a pair of Krell amps and I am running them at 240v. Had a pair of 12/3 240v 20A cables made. If nothing else it is cheaper to run. 222 is the switch configuration for 240v
I'm a certified electronic technician and got shocked by a few Kilovolts when trying to repair a tube-based spectrum analyser a few years ago.
My wedding ring was too close to the high-voltage wire feeding the tube display and received the biggest static shock. I was holding a screwdriver in my hand which received the shock. My arm reacted instantaneously and the screwdriver ended stuck in the ceiling of my repair shop...This was when I stopped wearing my wedding ring for a few years until I sold my repair shop.
So I guess there is no place waiting for me in heaven :-).
I got rid of the 2 Krell captive stock power cords, since I wanted to experiment with the Shunyata Anaconda CX power cords. I ended up installing a Furutech Rhodium inlet on my monoblocks and really enjoyed the audio improvements with the CX power cords.
According to the MBL article, using 10 gauge wire is the first step to audio heaven
Just be careful or you WILL end up in Audio heaven......
Probably not too many Krell owners who went for 220 VAC operation.
Probably not but the amps do come with a 20 amp outlet, their stock power cords then change it down to 15 amp plug - to fit your average house here - for sales I guess. All Krell owners I know use a 20 amp cord on a 20 amp circuit. I do with my FPB600.
I’m all in with your comments and this is why I’m doing this. According to the MBL article, using 10 gauge wire is the first step to audio heaven and moving to 220 VAC is the second step.
This is going to be a nice experience and looking forward to share my observations with the Gon community.
Thank you dasign . I grew up on farm in NY 50 miles from Montreal . Been there hundreds of times , beyond doubt , the best city in North America with a great Symphony Orch . My uncle used to play classical music from Montreal because it calmed the cows down, Mozart was their Favorite , we always sad the cows spoke French . Had a landed immigrant visa once upon a time, letting family talk me out of it was biggest mistake I ever made .
Started looking into Siemens 240 VAC/20 A circuit breakers. I may just go direct doing the 240 VAC mod, since the core of the work is rewiring the dedicated circuits to 10 gauge wire.
I had (stupidest thing I have ever done, selling it) a Krell KSA-250 power amp. Used it in Europe on 220V/50Hz and in the USA 110V/60Hz and can't honestly say I noticed any difference in sound quality. How I miss that amp!
Thanks for the invite, but I love my Canada. Well, if your gear sounds better ‘down under’, good for you guys and say hello to Crocodile Dundee 😎 on my behalf. We get 220 VAC coming in the electrical box on 3 wires with two phases ( 2x110 VAC). I will communicate my findings sometime next week when I’m done.
From what I understand make of this what you will.
For 220V, a 110v transformer is installed in the power box with 110-0-110 secondary windings - with 0V (centre tap) tied to earth. This gives you 2 phases (0, 180) which = 2x 110V.
Gee, was hoping to get more feedback on my post...Probably not too many Krell owners who went for 220 VAC operation.
I will probably start re-wiring with 10 gauge and keep the operation at 120 VAC and see where it brings me. Once I have a better understanding of the larger gauge wire benefits at 120 VAC, I will switch operation to 220 VAC and see if I gain something there.
I want to keep my cost as low as possible, so will do the rewiring myself. Will have the electrician only work on the electrical panel to replace the breakers for 220 VAC operation
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