DIY Audio General - stuff you're making, tips, advice sought, etc

You once said that the output transformers in my monoblocks were about the size of a small babies head. By comparison how big are those buggers!

They’re pretty similar, maybe a bit larger.

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About the size of two sardine tins by the look of it…

I have started going to the gym. :sunglasses:

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I hope you’re gonna polish that copper

After becoming fed up with the spikes on the base of the H6’s I have just made a test mini stand to see if it makes moving them around easier. It does a little. The M8 threads directly into the MDF (as designed by impulse) is pretty shite - I think I may carefully fit some metal rivet bushes

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You are aware that the height above the floor level is crucial to bass tuning (probably).

Yes - the design gives the same exit area that I had set up with the spikes.

One of things I got sorted on mine, they have a habit of splitting if you don’t sort it

I am not surprised - I have no splits but the threads are very weak. Bushes ordered.

Wiring up @chelseadave’s tube/SIT hybrid.

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Foo resistors!!

AN Silver Talentums and what is the other one? Mills? Vishay?

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Welwyn wirewound.

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Very nice.

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Yeah but it’s no Astra radio.

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W22. Lovely things. Apparently you can run them up to cherry red hot and when they cool down the resistance won’t have changed. Much.

VB

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Been refining the speaker design, with some medium and low density foam (1.5inch thick each) on the rear which has given a much smoother impedance curve, and subjectively sounds clearer and tighter

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I’m currently buying bits for an enclosure to house a MiniDSP 2x4HD (to use as a Preamp as well as the DSP/Active Crossover) and want to add some extra analogue inputs as it only has one built in.

I’ll make a simple plywood case to start with.

I’ve sorted the RCA connectors, its just the 8-pole rotary switch and internal cable spec I’m not sure on, any recommendations?

I’m not sure about the need for an 8-pole switch Rob - do you mean an 8-way one ? The poles refer to how many channels you’re switching - for stereo that’ll be two. The ways refer to how many inputs you want each pole to be able to handle, and also correspond to how many physical positions the switch can rotate through.

For historical reasons the most common rotation angle in rotary switches is 30 degrees. This allows one full rotation to be divided into 12 positions. When you look at the back of the switch there will be one output tag in each of those positions. You can arrange the switch to divvy the output tags up as 1-pole 12-ways, or 2-pole 6-ways, or 3-pole 4-ways, or 4-pole 3-ways, or 6-pole 2-ways. The most easily available is 2-pole (i.e. stereo) 6-ways. The input tags (one for each pole) may be in the centre of the switch, or squeezed in between the output tags.

If you really need 8-ways then I fear you’ll have to track one down from a specialist manufacturer, which won’t be cheap. A somewhat more common option would be a stacked wafer switch, but again they can take a bit of finding.

Reasonably priced 2-pole 6-ways can be had from Farnell or CPC or RSComponents. Posher ones can be had from e.g. HiFi Collective here. In this case you’d hope for better build quality (so smoother action and longer life) and nicer contact design/material (so lower contact resistance and maybe less switching noise).

As far as internal cable goes, you might get away with simple wire pairs for short runs. A trick to keep them short if you have the sockets on the back of the box but the switch knob on the front is to move the switch itself to the back, near the sockets, and connect it to the knob with a long metal rod. Rods and connectors for this purpose can be bought. Otherwise use screened lead - there will be less noise that way. Cheapest solution is to chop up a stereo phono lead, using the bit with the plugs on to plug into your mini dsp. Otherwise drop me a PM and I’ve got some ‘ordinary’ Van Damme studio hookup lead on a reel here.

VB

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Thanks Graeme, sorry that sounds like I’m after a 2-pole 3-way rotary switch (3x pair in, 1x pair out)