KISS

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karatestu
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Re: KISS

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More listening done over various CD's and styles of music.

I can't quite believe how fecking good an upgrade this is (I always say that you might say :roll: ). This goes back right to the fundamentals of the music much like NVA kit does. I am not going back to filtered amps now. People have said in the past that these filters are not audible and you are much better with them in for safety reasons.

Well, once i have tested these filter less for a month or two I will not be reinstating them. It is an improvement which I think is higher in magnitude than even giving the amp's front end it's own regulated power supply. I can't wait to try it on an amp with separate psu's for front end and output stage.I will do it with these old stunt amp boards first- all it takes is the lifting of one end of a resistor and a couple of wires from my the added psu's (which are all ready built ready).

:dance: :dance: :dance: :dance:

Thanks to the doc for encouraging me to try it, I was rather nervous at first. :clap: I wish I had the knowledge to see what else I could discard from the circuit :lol: :lol:
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Alfi
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Re: KISS

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:dance: Well you've got far more electronics knowledge than I have m8! :clap: :clap: :clap:

Did you have to tweak the bias and did the mod affect DC offset?

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Re: KISS

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Alfi wrote: Wed Feb 07, 2018 1:36 pm :dance: Well you've got far more electronics knowledge than I have m8! :clap: :clap: :clap:

Did you have to tweak the bias and did the mod affect DC offset?

Alfi.
Hi Alfi,

I only attempt something once I am fairly confident that things will be ok and the magic smoke won't be released. Sometimes all it takes is a bit of thinking and research to spur me on. After all the years of reading stuff on the internet about naim and Avondale amps what I have just done is totally against the grain. An eye opener for sure. I know (most) manufacturers tend to make product to be fool proof and unconditionally stable because they don't know what is going to happen to it when it has left the factory. Having bought some LS6, being aware it is very low C (and the information in Doc's & Lurcher's posts here) I finally had the courage to give it a go.

Bias has remained where it was set prior to doing the mods. DC offset - I thought it had actually reduced slightly. Don't know how that happened but it is a bonus.

One more thought - removing the output inductor, damping resistor and zobel may have reduced the amps output impedance a smidge. That can only be a good thing. There is no resistor on the output at all now (unlike Naim who put a 0R22 in there)

Stu.

Stu
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Re: KISS

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Keeping it simple and less is more are terms that i am now starting to understand with regards to hifi. Removing filters seems to be the order of the day - power amp filters, crossover filters etc. I have not tried a passive pre amp yet but that is on the to do list for sure. It would be great to get the preamp circuitry out of the way and its associated power supply- less circuitry in the signal path, less real estate taken up and less emi from the transformer being removed. Just wish i only had one source then i would get rid of the selector switch. And taking that further, if i only listened at one volume i could dispense with the potentiometer as well :lol:

Where kiss falls down though is with power supplies. Bigger and more additional psu's are the way forward. Hardly keeping to the less is more principle but hey i dont mind.

As an example my CD3.5 came with one transformer and psu which powered everything. I added a diy psu for the anologue stage. Better ? Oh yes indeed. Next up was a new fancy clock which i built a dedicated psu for. This mod blew me away. I then progressed to the dac. I ended up powering all three voltage supply pins independently with their own rectifier, caps and fancy regs. The only thing they shared was an EI transformer but this transformer has 3 secondary windings :dance: That mod really impressed me. So a cdp with one psu ended up with four independent psu's and is clearly far superior. I have another stock Naim cd3.5 to compare it to. Further plans were to try every opamp in the anologue output stage (6 of) with it's own independent psu. That will add another four transformers and psu's. Not sure if that will happen but i am always considering it.

On the NVA front (and my Avondale amps) the amps have independent psu's for the input and output stages when you get to the top of the range. The doc does not regulate the input stage but the Avondale does. Taking it further the statement amps add even more psu's so the LTP, VAS, driver and output stages are all independent. This could also be tried with the Avondales. Regulating power amp front ends adds complexity but then the input stage can be considered as a preamp and look at the lengths some people go to regulate them. I will try both ways.

Also phono stages need to be powered, additional and, bigger psu's seem to work there as well. :dance:

So whilst i am keeping it simple in some ways, in other ways i will be adding more amplifiers and more psu's to them, the cdp and phono stage.

Stu (where will it all end ?)
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Re: KISS

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Hopefully not in disaster m8.

Learn when to be satisfied too and revel in the results of all you work :mrgreen:

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Re: KISS

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Alfi wrote: Sun Feb 11, 2018 9:26 pm Hopefully not in disaster m8.

Learn when to be satisfied too and revel in the results of all you work :mrgreen:

Alfi.
Yes Alfi, hopefully not disaster. Luckily i am very very careful with these things. Check 3 times before turning on and one mod at a time. Research each extensively before commencing.

Being satisfied is something i will have to live with eventually. It is so easy to become obsessive and there is only so far this can go before i run out of things to try. Speakers are more or less proven except messing about with steel and bracing. Building the final production cabs i may pass to a joiner friend. Although the doc teased me with him going one better with the cubix pro i.e 3 drivers in isobaric configuration. Evil . :twisted: :lol:

Stu
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Re: KISS

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More listening done with a few different discs and I am even more impressed with my filter less amps. I noticed some things on Led Zep IV and in introduction to Nick Drake this lunch time that I have never heard before. So there is more detail but each of the instruments sound more full and open. It really is a joy to listen to. I noticed some bass detail on zep IV that was masked before - there is a distinct lack of John Paul Jones on IV and the more of him I can hear the better. The strings and guitar on nick Drake are illuminated and every pick or bend of a string is clearly more evident. More tone, more harmonics - lovely.

Getting rid of components does really pay dividends. Fewer solder joints, phase anomalies and parasitic capacitance and inductance- result is better music. After all a capacitor will have inductance and an inductor will have capacitance. Circuit design becomes harder the more I think I know about it :think:

Stu
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Re: KISS

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Bloody hell my amps can now make sense of Radiohead. All that have gone before have failed miserably :grin: Never tried the AP20 with Radiohead....yet.
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Re: KISS

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karatestu wrote: Wed Feb 14, 2018 2:20 pm
Getting rid of components does really pay dividends. Fewer solder joints, phase anomalies and parasitic capacitance and inductance- result is better music. After all a capacitor will have inductance and an inductor will have capacitance. Circuit design becomes harder the more I think I know about it :think:

Stu
The Doc has been saying this for years Stu and now you've found it out for yourself. :clap:

I have a dilemma now, what to do with my two Avondale NCC 200 Mono's - excellent dynamic amps with plenty of oomph but nowhere near as sweet as the little A20. What ya think :?:

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Re: KISS

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Alfi wrote: Fri Feb 16, 2018 9:55 pm
karatestu wrote: Wed Feb 14, 2018 2:20 pm
Getting rid of components does really pay dividends. Fewer solder joints, phase anomalies and parasitic capacitance and inductance- result is better music. After all a capacitor will have inductance and an inductor will have capacitance. Circuit design becomes harder the more I think I know about it :think:

Stu
The Doc has been saying this for years Stu and now you've found it out for yourself. :clap:

I have a dilemma now, what to do with my two Avondale NCC 200 Mono's - excellent dynamic amps with plenty of oomph but nowhere near as sweet as the little A20. What ya think :?:

Alfi.

Hey Alfi how's it hangin',

What you need to do is this;

Remove input stage coupling capacitor
Remove wiring between zobel and cap bank 0V
Remove wiring between output spade and positive output on back of amp
Solder a wire from the big pcb area where the ballast resistors (0R22) are joined to the output inductor, to the positive speaker output on back of amp.
There are a few unused holes in the pcb in this plane which were put on to accommodate different component sizes. Use one of those.

This will improve the sound considerably. I found the result to be more satisfying than giving the front end its own regulated power supply. I cant wait to combine the two modifications :grin:

But none of this will fully remove the "rip" as Les calls it. To do that you need to convert the board to a fully complimentary output stage. Remove the baxendall diode and a resistor, change the value of 6 resistors and swap the output transistor on the negative side to a pnp.

When i have found out the exact details and tested it myself you can just send me the amp modules and i will do it for you - free of charge of course :dance:

Stu
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