…..as an absolut term.
But MoFo seems to have the mid tones like a 300B but with more bas control. I felt a deeper bas in the room compared to ACA. I use the track "Drums stop no good" with Steve Smith to test that (do you know that track?). I have some reference tracks I listen to when I have new equipment to listen to. I think the "Drums stop no good" it very good to test the power of an amp in the low end. Also some pipe organ tracks played on large organs is a good test for bas response.
Mid and high tones compared to ACA my subjective feel is that ACA sounds a bit on the "hard" side compared to MoFo. But still ACA sounds very good.
I have to listen to MoFo long time to be sure that what I heard first time is also the conclusion after long time. But that I could listen for hours is a good sign.
Such a large choke will have a good response on 10-20 kHz? Is the core of a material for audio? What was the price of this choke I am really interested to buy some!
Good point about low dcr to avoid output cap. Maybe for a mid Amp starting from 300hz it would be possible to wind an air coil with 0.001ohm dcr and use 500ma bias... No need for output cap. For bass use a push pull Amp...
Good point about low dcr to avoid output cap. Maybe for a mid Amp starting from 300hz it would be possible to wind an air coil with 0.001ohm dcr and use 500ma bias... No need for output cap. For bass use a push pull Amp...
I could see no drop in response at 250 kHz (my generator does not go higher) so no problem with high frequencies. Square wave also looked good…..not a 100% perfect square but still very good. Price for two chokes was 5000 DKK incl tax….I think that is about 800 USD or 700 Euros. I picked them up at the factory. They may be expensive to ship as they are 20 kg each. If you take a vacation in Denmark you can pick them up.
There is this place you can stay very close to the factory…..very good food 🙂 :
https://gerlev-kro.dk/
I have discussed core material with the company (they also make high-end tube output transformers) and as I could understand.....there is a lot of "woodoo" about this. They have tried to unwind very expensive output transformers from very known companies but did not find any secrets. The iron they used for this choke has a name (number) but then I have to ask what they used.
2.5 A bias gives a DC offset = 182 mV. For me that is a little too much not to use an output cap. Maybe for safety it is good also.
I have the order confirmation etc. so it will be easy for the company to make two more 🙂
There is this place you can stay very close to the factory…..very good food 🙂 :
https://gerlev-kro.dk/
I have discussed core material with the company (they also make high-end tube output transformers) and as I could understand.....there is a lot of "woodoo" about this. They have tried to unwind very expensive output transformers from very known companies but did not find any secrets. The iron they used for this choke has a name (number) but then I have to ask what they used.
2.5 A bias gives a DC offset = 182 mV. For me that is a little too much not to use an output cap. Maybe for safety it is good also.
I have the order confirmation etc. so it will be easy for the company to make two more 🙂
Thank you for your response.
Did not know of the drums track.
I see it's available on Tidal so will
give it a listen.
A fair recording of drum set, simply recorded is
"Birdman (Original Motion Picture Soundtrack) by Antonio Sanchez".
I recently came across a live recording that has a natural sound to it,
"Live And Unplugged by The Struts".
Cheers
Yes, I also use Tidal. The MQA recordings (24 bit) are very nice. Also still some very good CD recordings (16 bit music).
I found the "Birdman"...….some nice drums.
The "Drums stop no good" also has a very deep bass guitar. The combination played at loud playback is a good test. It has some "slam" which is a good test to check if an amp has some "muscles".
Heard it first time watching a "Kenrick sound" video. They restore old JBL speakers like this one (do you remember this "furniture" from the "old days"?):
YouTube
I found the "Birdman"...….some nice drums.
The "Drums stop no good" also has a very deep bass guitar. The combination played at loud playback is a good test. It has some "slam" which is a good test to check if an amp has some "muscles".
Heard it first time watching a "Kenrick sound" video. They restore old JBL speakers like this one (do you remember this "furniture" from the "old days"?):
YouTube
Thanks a lot for all nice info about the chokes. They are wonderful! But the price tag is quite high for me...
My idea is to build a smaller mofo only for mid and high freq and use a push pull Amp for bass.
At what low freq the damping factor is important for tight bas? Below 300hz? Or 600hz?
My idea is to build a smaller mofo only for mid and high freq and use a push pull Amp for bass.
At what low freq the damping factor is important for tight bas? Below 300hz? Or 600hz?
The cross over to my 15" woofer is about 180 Hz. So below that is my guess. Many like a not too high damping factor but to control a 15" woofer…..then around 20 I would say. But there are too many opinions about that. Don't think the damping factor can "stand alone". But I think MoFo has more bass control than ACA. Probably because it can deliver more current when biased to 2.5A. Too tight a bas can also sound unnatural. It has to be tried. It is difficult to get an integrated sound using two amplifiers. Think you need some audio measure equipment to help tuning the system. I think it was hard to find the correct level for the bas amplifier when it is two different kind of amplifiers. It is easy to set the bas amp to a higher level than it should because it sounds impressive but then you get tired and then you turn down…..and then you think…..now it is too weak…...etc.....not easy…...I gave up 🙂
Paragon. Yes, I was about 15 or so years old and saw them in an audio magazine I bought in the late 50's early 60's.
I'm not into dub or trance but had come across this on TIDAL, give it a listen.
The Razorgirl track #4 by Dubvirus, album is "DEF CON 24: The Official Soundtrack".
Heard it in an episode of "Mr. Robot" and had to track ti down.
Cheers
any news aboit the MuFo MoFo Part II ?
any sugestion for cheaper and smaller chokes than original for low power MoFo 0.5A bias?
any sugestion for cheaper and smaller chokes than original for low power MoFo 0.5A bias?
If has been discussed in the thread below where MR made some experiments with smaller chokes not long time ago. Maybe you can get some ideas there:
MoFo inductor options for use above 1kHz only
MoFo inductor options for use above 1kHz only
in this thread they discuss about less mH to use from 1KHz
I need same 50mH but smaller core and wire for less current
I need same 50mH but smaller core and wire for less current
A Hammond 159zc rated at 2A and 60mh comes close
or at 50mh 1.58lb of # 20 copper wire on a 1" diameter and 1" long
form might work but it would also have 5.27 ohms resistance so it
could get hot if used much above 1/2A.
or at 50mh 1.58lb of # 20 copper wire on a 1" diameter and 1" long
form might work but it would also have 5.27 ohms resistance so it
could get hot if used much above 1/2A.
Ok.....so you still want to have full frequency range from 20Hz to 20kHz but just a MoFo that only output maybe 5W instead of 25W?
Then you will probably get more distortion?
There is still the small MoFo that bias at 1.7A.....using the small Hammond choke…...but you need it even smaller...…..
Regarding blowing mosfets, don't know if this affects anyone or if it's truly relevant, but there are IRFP250 mosfets with different specs.
The Vishay/Siliconix mosfets have lower Vgs and power dissipation than the Infineon mosfet. Vgs threshold is lower in the Vishay as well.
IRFP250 MOSFET | Mouser
The Vishay/Siliconix mosfets have lower Vgs and power dissipation than the Infineon mosfet. Vgs threshold is lower in the Vishay as well.
IRFP250 MOSFET | Mouser
The Vgs limit for Vishay is still 20V (so my 20V zener will still protect).
https://docs-emea.rs-online.com/webdocs/0e30/0900766b80e309c4.pdf
The Rds(on) is specified as Vgs = 10V, and 85 mOhm (75 mOhm for the Infinion).
Detailed spec. for the Infinion…..is that IOR (RS link to IOR data sheet)?
https://docs-emea.rs-online.com/webdocs/0791/0900766b8079120f.pdf
https://docs-emea.rs-online.com/webdocs/0e30/0900766b80e309c4.pdf
The Rds(on) is specified as Vgs = 10V, and 85 mOhm (75 mOhm for the Infinion).
Detailed spec. for the Infinion…..is that IOR (RS link to IOR data sheet)?
https://docs-emea.rs-online.com/webdocs/0791/0900766b8079120f.pdf
Hi guys!
Having (more or less) all the parts, a quick question(s), so please clarify for me:
Mr. MR (I have seen it many times written on forum, never gave it second taught, but now when I write it.. 🙂 has wrote in MoFo document that protection diode is 20V zener. A few pages before ZenMod (and others) suggested that zener should be anything between 6V and 12V (or something like that). So, having both, which should I choose, or, for protection purposes it doesn't matter?
and second, I have seen that output capacitor C2 (6800 uF) has been (mostly) increased to other values, so (again) having some decent quality Panasonics 10 000 uF that should be better than locally available 6800uF, what am I doing by increasing C2 value?
Thanks!
Having (more or less) all the parts, a quick question(s), so please clarify for me:
Mr. MR (I have seen it many times written on forum, never gave it second taught, but now when I write it.. 🙂 has wrote in MoFo document that protection diode is 20V zener. A few pages before ZenMod (and others) suggested that zener should be anything between 6V and 12V (or something like that). So, having both, which should I choose, or, for protection purposes it doesn't matter?
and second, I have seen that output capacitor C2 (6800 uF) has been (mostly) increased to other values, so (again) having some decent quality Panasonics 10 000 uF that should be better than locally available 6800uF, what am I doing by increasing C2 value?
Thanks!
there is no practical difference between 6V and 20V protection zener , only that smaller value is sorta more conservative
I've seen myriad times Papa putting 9V1 there, it works and he obviously have them in truckloads quantity
output cap - more capacitance , lower F3 ...... or smaller phase twist on "F3" of interest
as usual in DIY projects - when in doubt , double it
I've seen myriad times Papa putting 9V1 there, it works and he obviously have them in truckloads quantity
output cap - more capacitance , lower F3 ...... or smaller phase twist on "F3" of interest
as usual in DIY projects - when in doubt , double it