Another MoFo

What people are working on at the moment
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Ray P
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#166 Re: Another MoFo

Post by Ray P »

Good stuff Phil - looks like the project is working out well.
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pre65
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#167 Re: Another MoFo

Post by pre65 »

Ray P wrote: Thu Jul 09, 2020 6:49 pm Good stuff Phil - looks like the project is working out well.
Thanks Ray.

I drilled and tapped the mosfet and PCB mounting holes and populated the second PCB a while ago, but that's it for tonight.

The MOT spade terminals were smaller than I realised, so I've "bodged" them until the proper 4.8mm ones turn up

I'd like to think I'll have stereo MoFo's this weekend. :D
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pre65
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#168 Re: Another MoFo

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I've just fired up the second unit, and I'll leave it playing on the test bench for an hour before tweaking the bias to its final value.

I don't anticipate getting them set up in the main system tonight, but something to look forward to in the morning. :)
Life is what happens to you while you're busy making other plans. John Lennon

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pre65
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#169 Re: Another MoFo

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Well, of course, I couldn't wait till the morning. :)

I'm playing a Carpenters CD, and the sound quality is different from what I'm familiar with.

Seems clearer, and more expansive. Bass is clearer, and a bit more of it, but it's not prominent. Karens voice is even more delightful than I remember. Can't find any disadvantages at the moment.

Obviously need more listening time with different types of music to really get a handle on things.
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#170 Re: Another MoFo

Post by steve s »

I found it's a nice mix .. I think mine combines all the advantages of no output transformer valve amp and what solid state aspires to be.. . If that makes sense
No colour/ greyness/ lack of detail
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#171 Re: Another MoFo

Post by pre65 »

Stereo MoFo's. :D

After a bit of thought I went for the BIG 6800uf capacitors, and mounted them as close to the PCB as possible.

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#172 Re: Another MoFo

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I've switched off now, 'cos I'm going for a walk soon.

I've tried a varying selection of my musical tastes, but as I'm liking what I hear I'll play some more when I return.

I'm considering getting a pair of Hammond 193V chokes, 150mH @ 3A, now that the amp is worth refining.

What chokes did you use Steve ?
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#173 Re: Another MoFo

Post by steve s »

I used 193t, I cant imagine a bigger choke will make it sound any better unless you need more power
The tube manual is quite like a telephone book. The number of it perfect. It is useful to make it possible to speak with a girl. But we can't see her beautiful face from the telephone number
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#174 Re: Another MoFo

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pre65 wrote: Sat Jul 11, 2020 11:30 am Stereo MoFo's. :D
:thumbup:
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#175 Re: Another MoFo

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steve s wrote: Sat Jul 11, 2020 3:24 pm I used 193t, I can't imagine a bigger choke will make it sound any better unless you need more power
You may be right Steve. :)
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ed
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#176 Re: Another MoFo

Post by ed »

if you really must tinker with it why not try a couple of exicons. I'm willing to bet it will be more enlightening than a couple of expensive chokes. They might cost you £4 each but well worth the experience.
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#177 Re: Another MoFo

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Thanks Ed, but I don't have the skills to select one that would work, and then it's a gamble.

I'll stay with what I've got for now.
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#178 Re: Another MoFo

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ed wrote: Sun Jul 12, 2020 5:21 pm if you really must tinker with it why not try a couple of exicons. I'm willing to bet it will be more enlightening than a couple of expensive chokes. They might cost you £4 each but well worth the experience.
Reading up, my impression is there are advantages to having the choke there, it works similar to choke loading a valve ?
Also reading DIY audio, mosfets can start to sound a little grey when used as a voltage gain amplifying device...thats only what I've read so dont shoot me down... but this thing does not sound grey, just very open.
The amp sounds different.. I think it's good,
But what to I know..
If i messed with a suitable exicon or any other mosfet (unless I was sure otherwise) I'd probably still put a choke with it.. I like what it does
The tube manual is quite like a telephone book. The number of it perfect. It is useful to make it possible to speak with a girl. But we can't see her beautiful face from the telephone number
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#179 Re: Another MoFo

Post by Nick »

Unless I am missing something, that circuit wont work without a choke. I think ed means use a different mosfet as the power device.
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#180 Re: Another MoFo

Post by steve s »

Nick wrote: Sun Jul 12, 2020 7:18 pm Unless I am missing something, that circuit wont work without a choke. I think ed means use a different mosfet as the power device.
One of my many skills is misreading nick, my apologies Ed.. 😃
The tube manual is quite like a telephone book. The number of it perfect. It is useful to make it possible to speak with a girl. But we can't see her beautiful face from the telephone number
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