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4 or 8 ohm connection

Postby ronj » Wed Jan 11, 2017 8:41 pm

I ordered a Yaqin MS-20L amp that is being delivered. It has speaker outs for 4 and 8 ohms.
Which should I use for 6 ohm Klipsch KG4's?
Any suggestions/recommendations much appreciated.
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Re: 4 or 8 ohm connection

Postby Hugh Robjohns » Wed Jan 11, 2017 9:12 pm

I suspect it will work best on the 4ohm setting, but either should work.

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Re: 4 or 8 ohm connection

Postby ronj » Wed Jan 11, 2017 10:01 pm

Thank you for your feedback
Cheers,
Ron
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Re: 4 or 8 ohm connection

Postby ef37a » Thu Jan 12, 2017 9:07 am

I agree with Hugh in that it will likely not matter very much.
I am going to differ from him though and say set the amp for 8 Ohms. This is because speaker impedance really only increases with frequency (nominal Z is measured at 400Hz as a rule) and valve amplifiers are better at supplying more VOLTS than more AMPS.

But wow! I have just had a quick varder of that amplifier's product range. The valve is not likely to die out anytime soon as some pundits have said if just ONE maker is producing amplifiers like these and at very attractive prices to boot.

Any chance SoS could get a review sample?

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Re: 4 or 8 ohm connection

Postby Hugh Robjohns » Thu Jan 12, 2017 10:04 am

ef37a wrote:Any chance SoS could get a review sample?

You seem to have us confused with a hi-fi magazine... :lol:

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Re: 4 or 8 ohm connection

Postby Martin Walker » Thu Jan 12, 2017 12:01 pm

It does look good though! ;)

Image


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Re: 4 or 8 ohm connection

Postby ef37a » Thu Jan 12, 2017 12:48 pm

Hugh Robjohns wrote:
ef37a wrote:Any chance SoS could get a review sample?

You seem to have us confused with a hi-fi magazine... :lol:

H

Not in the slightest degree Hugh! I gave up the last bastion of sense, Hi Fi News many years ago when the beardy tweaks took over.

You are not a guitar magazine and yet you regularly review amps and pedals and other such stuff* But to be serious, I really would like an objective opinion on that amp (as it pertains to studio work) .

*Mind you! Peeps COULD be forgiven for thinking SoS is part the KEYBOARD/SYNTH "Times"? Nary a copy without some such box making the same old funny noises!

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Re: 4 or 8 ohm connection

Postby Hugh Robjohns » Thu Jan 12, 2017 1:39 pm

ef37a wrote:You are not a guitar magazine and yet you regularly review amps and pedals and other such stuff...

I think we've had this discussion before. We occasionally -- not regularly -- review guitar amps and pedals but the entry threshold is that they must offer something particularly interesting and relevant to home/project studio recording applications. Similarly, we occasionally review things like hum-bucking pickups and related systems but only when their is a specific relevance to recording applications.

We don't review products which are exclusive to hi-fi applications, although some of the studio gear we review does have hi-fi applications (like the Benchmark DAC2 or the Grace m903).

But to be serious, I really would like an objective opinion on that amp (as it pertains to studio work) .

Would anyone really want to use that in a studio? I think you'd be better scanning the hi-fi magazine for a review, Dave. Can't see it being given any pages in SOS any time soon.

Mind you! Peeps COULD be forgiven for thinking SoS is part the KEYBOARD/SYNTH "Times"? Nary a copy without some such box making the same old funny noises!

We've covered synths since issue 1 in 1985 and it has ALWAYS been a core part of the SOS reviews and features content.

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Re: 4 or 8 ohm connection

Postby ore_terra » Thu Jan 12, 2017 1:40 pm

With guitar valve amps I'd set the amp always at a lower impedance than the speaker's, otherwise wouldn't be good for the amp.

Dont know if it will be any different for hi fi, to be honest.


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Re: 4 or 8 ohm connection

Postby ef37a » Thu Jan 12, 2017 3:45 pm

ore_terra wrote:With guitar valve amps I'd set the amp always at a lower impedance than the speaker's, otherwise wouldn't be good for the amp.

Dont know if it will be any different for hi fi, to be honest.


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No! Putting a LOWER load on a valve amp than the tapping is almost always ok . If you drive the bejesus off a big one you might redplate and pop a fuse but afterwards no harm done.

Running at a lower tap into a higher Z causes very high voltages to be generated and they can cause arcing, valve and possibly output transformer failure. Once again, size, of amp and signal, matters. To specify...
Amp setting 4R speaker 8R. Not good but safe with care.
Amp setting 4R speaker 16R. Avoid but safe for VERY low level practice
Amp setting 8R speaker 4R. Ok but heavy drive might pop a fuse. Do not run for too long at high drive.
Amps setting 16R speaker 8R. Ok but as above and even more likelihood of a fuse pop if a 4 Ohm speaker.

N.B. Not all guitar amps have HT fuses or if they do they are inside. Some amplifiers have much more "fragile" output transformers than others!

Hugh. Tongue was in cheek a bit!
I am NEVER going to get an objective amp review from a hi fi mag now am I?

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Re: 4 or 8 ohm connection

Postby Hugh Robjohns » Fri Jan 13, 2017 10:26 am

ef37a wrote:I am NEVER going to get an objective amp review from a hi fi mag now am I?

:lol: I used to have some faith in Hi-Fi News and Record Review, and Paul Miller's technical lab tests have always been extremely good. However, I've not seen a copy on the newsagent's shelves for years (not that I look very often -- usually only when I'm at Paddington station, in fact, and wanting a distraction for the journey back home!). They do still seem to be in business, though. Stereophile in the USA also manages some objective technical reviews.

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Re: 4 or 8 ohm connection

Postby ore_terra » Fri Jan 13, 2017 12:47 pm

Well, ef37a, my main target would be safety and (even more sometimes haha) integrity of a good amp's components. Im afraid it wouldnt be just a fuse what would blow!

Bear in mind that we're speaking of valve power stages here.


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Re: 4 or 8 ohm connection

Postby ef37a » Sat Jan 14, 2017 7:38 am

ore_terra wrote:Well, ef37a, my main target would be safety and (even more sometimes haha) integrity of a good amp's components. Im afraid it wouldnt be just a fuse what would blow!

Bear in mind that we're speaking of valve power stages here.


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Re: 4 or 8 ohm connection

Postby James Perrett » Sat Jan 14, 2017 8:52 pm

ore_terra wrote:Bear in mind that we're speaking of valve power stages here.

I think you'll find that Dave (ef37a) is intimately familiar with valve power stages ;)

His advice is pretty sound - and I speak from personal experience having damaged a valveholder by setting the impedance switch to a low setting while trying to drive a higher impedance speaker. It may seem counter intuitive to someone brought up on solid state amplifiers but transformer speaker outputs don't like to drive higher impedances.
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Re: 4 or 8 ohm connection

Postby Folderol » Sat Jan 14, 2017 9:09 pm

James Perrett wrote:
ore_terra wrote:Bear in mind that we're speaking of valve power stages here.

I think you'll find that Dave (ef37a) is intimately familiar with valve power stages ;)

His advice is pretty sound - and I speak from personal experience having damaged a valveholder by setting the impedance switch to a low setting while trying to drive a higher impedance speaker. It may seem counter intuitive to someone brought up on solid state amplifiers but transformer speaker outputs don't like to drive higher impedances.

What I want to know is who thought it a bright idea to put the anode pin right next to a heater pin?
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Re: 4 or 8 ohm connection

Postby ef37a » Sat Jan 14, 2017 9:49 pm

Would you rather it arced over to the control grid Will?!

I did in fact write a further, longish response but hit a wrong key editing and it all got deleted. Any chance of getting an auto draft function?

Long-short. An OC load presents an infinite load times "n" the turns ration and in theory any signal current gives rise to an infinite (X n) anode voltage. In practice, interwinding capacitance provides some load but several kV can easily be generated. Large inductors are tricky beasts!
Higher than correct loads can still cause large voltages and flash over and damage.

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Re: 4 or 8 ohm connection

Postby Folderol » Sun Jan 15, 2017 10:16 am

ef37a wrote:Would you rather it arced over to the control grid Will?!
Dave.
Pah! They should never have done away with top caps :protest:
Mind you, I remember they could never make up their mind whether it should be anode or control grid (the only difference between AC/VP1 and AC/VP2) :o
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