Search found 4206 matches

by Andrew
Fri Feb 03, 2023 2:50 pm
Forum: Everyones Projects
Topic: C3g Aikido Phono
Replies: 319
Views: 81405

Re: C3g Aikido Phono

That makes a lot of sense Nick. Right, I've had a play and assuming I have a grasp of what's going on (dangerous!) it's been very interesting. Starting with the phono as it is currently: RIAA existing.png Two things that strike me: First, there's approx 0.18dB peak to peak difference in signal leve...
by Andrew
Fri Feb 03, 2023 9:10 am
Forum: Everyones Projects
Topic: C3g Aikido Phono
Replies: 319
Views: 81405

Re: C3g Aikido Phono

It depends what you want to study?

If you want to view what the RIAA correction looks like, then the wire that goes into the grid stopper on the first valve of the second stage is where I would start, use a directive something like '.ac oct 16 20 20k'.
by Andrew
Thu Feb 02, 2023 5:11 pm
Forum: Everyones Projects
Topic: C3g Aikido Phono
Replies: 319
Views: 81405

Re: C3g Aikido Phono

I would guess you don't have the 6N6P model, try something in the standard Duncan amps fileset.

PS It probably makes sense to use whatever valves you have in the circuit.
by Andrew
Wed Feb 01, 2023 6:29 pm
Forum: Everyones Projects
Topic: C3g Aikido Phono
Replies: 319
Views: 81405

Re: C3g Aikido Phono

simon wrote: Wed Feb 01, 2023 5:58 pm Thanks but no. It seems to be finding the xpentode4 model and everywhere I've copied the xpentode4 model to I've also copied the inverse_RIAA model. Odd

Ah hang on, I might have missed this :oops:
by Andrew
Wed Feb 01, 2023 2:40 pm
Forum: Everyones Projects
Topic: C3g Aikido Phono
Replies: 319
Views: 81405

Re: C3g Aikido Phono

Well this doesn't bode well, I've failed at the first chuffin hurdle - I can't get the inverse RIAA to load. I've copied it to the top level below the LTspice folder, to the lib folder below and the sym folder below that but no joy. When I open C3g_aikido.asc it tries to load the inverse RIAA but I...
by Andrew
Tue Jan 31, 2023 5:35 pm
Forum: Everyones Projects
Topic: C3g Aikido Phono
Replies: 319
Views: 81405

Re: C3g Aikido Phono

You might need to fix up the wiring between the iRIAA and the circuit, but it works :)
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Untitled.png (90.76 KiB) Viewed 2974 times
by Andrew
Tue Jan 31, 2023 5:24 pm
Forum: Everyones Projects
Topic: C3g Aikido Phono
Replies: 319
Views: 81405

Re: C3g Aikido Phono

Here you go!
by Andrew
Tue Jan 31, 2023 5:16 pm
Forum: Everyones Projects
Topic: C3g Aikido Phono
Replies: 319
Views: 81405

Re: C3g Aikido Phono

OK, quick update, putting the RIAA in the same folder as your main .asc file works.

I am looking for the xpentode4 model, think I gave you a generic pentode.
by Andrew
Tue Jan 31, 2023 5:05 pm
Forum: Everyones Projects
Topic: C3g Aikido Phono
Replies: 319
Views: 81405

Re: C3g Aikido Phono

You'll need to configure LTSpice to include the correct valve models for this to work, Simon. Most of what you'll need is document in 'Stacks' on here, I think? But keeping it all easy, you can put 'pentode.asy' and the inverse RIAA in the location "C:\LTspiceIV\lib\sym\Misc", then follow ...
by Andrew
Mon Jan 30, 2023 8:30 pm
Forum: Everyones Projects
Topic: C3g Aikido Phono
Replies: 319
Views: 81405

Re: C3g Aikido Phono

So, add a 15k or 16k resistor before the RIAA, change the 470nF and 47nF caps for 100nf and 10nF, and the 680R and 68R resistors for 3200R and 320R? And the 1068R for 5020R? Is it that simple? Yes, kind of, but your'e better getting Spice out, to double check. Don't make life harder than it has to ...
by Andrew
Mon Jan 30, 2023 8:26 pm
Forum: Everyones Projects
Topic: C3g Aikido Phono
Replies: 319
Views: 81405

Re: C3g Aikido Phono

I think so yes. Maybe Andrew can comment on one thing - is the 1068R in your circuit a little trick to make the second RIAA cap a stock value ? Yes, it's all stock values and if I recall the 68R in series with the 1k adds a touch of nice bass lift, which compensates for speaker roll off and other l...
by Andrew
Mon Jan 30, 2023 8:26 pm
Forum: Everyones Projects
Topic: C3g Aikido Phono
Replies: 319
Views: 81405

Re: C3g Aikido Phono

But as mark did you can reduce the minimum load by keeping the 5k6 anode load but including a series r in the feed to the riaa. Err, I'm a bit rusty, so I would need to think that thru'! I wonder, out aloud, if you might need to increase the anode load on the pentode if you did that? The pentode lo...
by Andrew
Mon Jan 30, 2023 6:11 pm
Forum: Everyones Projects
Topic: C3g Aikido Phono
Replies: 319
Views: 81405

Re: C3g Aikido Phono

Well for example keeping the anode load at 5k6 but calculating the riaa to driven by 61k can be done by adding a 56k resistor in series before the riaa network. That way the pentode sees a more constant load and so distortion with Freq is more constant and the riaa is driven by a more stable load a...
by Andrew
Mon Jan 30, 2023 6:01 pm
Forum: Everyones Projects
Topic: C3g Aikido Phono
Replies: 319
Views: 81405

Re: C3g Aikido Phono

Also if you use a bigger coupling cap you can put it before the riaa and then your riaa caps don't have any voltage requirements. All choices. Choices I too once made and since backed away from. Also, it was originally designed to have the cap after the network, so it can be smaller, as Nick says, ...
by Andrew
Mon Jan 30, 2023 5:57 pm
Forum: Everyones Projects
Topic: C3g Aikido Phono
Replies: 319
Views: 81405

Re: C3g Aikido Phono

But as mark did you can reduce the minimum load by keeping the 5k6 anode load but including a series r in the feed to the riaa. Err, I'm a bit rusty, so I would need to think that thru'! I wonder, out aloud, if you might need to increase the anode load on the pentode, if you did that? The pentode l...