Mini Beast driving Cheviots anyone?

Non-Smoking Man

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The Transcendent Audio Mini Beast is, as many of us know, a 4 watt, 3 valves per side transformerless amp.
You might say that its a 'marmite' product, and that it is somewhat niche. It is predominantly available as a kit.

Tannoy Cheviots famously use a dualconcentric driver, and are very efficient - so, on paper, a prima facie match for the Mini Beast's miniscule output.

Anyone any thoughts on this potential match and on the merits or otherwise of transformerless amps in general, and the Mini Beast in particular?

Jack NSM
 

Jazid

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You can't tell until you try but I'd say that the Cheviots aren't that sensitive, they aren't a truly benign load for a high output impedance amp, and usually seem to like medium damping factor amps best. So I'd be surprised if it was ideal, but have been surprised many times before!
 

steve 57

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For what it's worth I wouldn't pair 89 db speakers with a 4 watt amp unless you listen at very low levels.
I've been lucky enough to have an afternoon of listening to one of these amps that my mate had just built.
As with all otl Amps you remove the output transformer and there is a very 'open' sound, really very nice,
The mini beast I heard ( and I've heard the same with a few otl amps), is that despite that open sound I've heard a lack of resolve
An example was on one track I played, (recorded live) was the audience applause sounded just like real clapping on my amps, unfortunately turned in to a football rattle via the mini beast.
 
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bencat

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My only experience of OTL amps is the Croft 3 OTL I own and use with my Quad ESL 57 speakers . My view is that OTL amps are a holy grail and very different from any other amp for me like others view SET amps a sound like nothing else . I do not think the power or the ability of the amp matters the quality and ease of an OTL is just different from other amplifiers and for me gets closer to the real music
 

Psilonaught

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Can I join this OTL amp thread? I was very interested in the Transcendent Audio brand when looking for OTL amps but their largest OTL is only 40w. That's why I went for the Atma-sphere ma1 amps instead.

Transcendent Audio look like a really good value and interesting brand.

I agree with the comments above regarding the open sound of an OTL amp. Mine use 6SG7 triodes. I find the sound extremely delicate and accurate, with excellent resolution.

I was worried I'd need autoformers as my speakers are 4 ohm but they are flat and don't dip below 4. OTL amps can drive a tricky load!

I mate mine with the true ribbon tweeters of my magnepan 20.1 series (class AB amps for the bass and mid bass panels).

A pretty extraordinary combination :)

Three cheers for OTL amps !
 

THOMO

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I borrowed a pair of Cheviots for a while.They are excellent speakers and have a slightly more punchy character than the other vintage Tannoys.They have really good rhythm and timing.I found they sounded best with a push pull EL34 amp around 30-40 watts although suspect they would sound good with as little as 15 watts.Not 8 watts from a 300B SET though so 4 watts OTL might not work well at all.
 
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THOMO

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I should add that if you like the OTL sound you probably should consider a Bakoon.They work brilliantly with Tannoy speakers.Even the baby 15 watt SCA 7511 Mk3 which is very affordable.WAR Audio in Australia seems to be the best place to buy 240 volt versions of them.
I use an AMP 5521 which is 35 watts with my Tannoys but the 15 watt ones work fine.They are SS but sound nothing like any other SS amp I have used.Much closer to a really good SET.But not the soggy euphonic type of SET more the ultra clear "open window" sort of SET.Which is also what I have heard from good OTLs.
 

bencat

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I should add that if you like the OTL sound you probably should consider a Bakoon.They work brilliantly with Tannoy speakers.Even the baby 15 watt SCA 7511 Mk3 which is very affordable.WAR Audio in Australia seems to be the best place to buy 240 volt versions of them.
I use an AMP 5521 which is 35 watts with my Tannoys but the 15 watt ones work fine.They are SS but sound nothing like any other SS amp I have used.Much closer to a really good SET.But not the soggy euphonic type of SET more the ultra clear "open window" sort of SET.Which is also what I have heard from good OTLs.
You and I have very different ideas of affordable the cheapest I saw was 6000 had which is about £5250 .
 

THOMO

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THE SCA 7511 MK3 is about $2500 Australian /1350 Stirling from WAR Audio.With free shipping I believe.These are the real deal Japanese Bakoons not the up marketed Korean versions.
 

bencat

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Sadly as most on here are based in the UK buying from Australia is not really an option . Shame they do not have any European or UK distribution .
 

THOMO

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Sadly as most on here are based in the UK buying from Australia is not really an option . Shame they do not have any European or UK distribution .
Nonsense.People buy components from all over the world every day from international distributors like Madisound and Solen.Why would buying from Australia be any different to buying from Europe?Especially now that the UK is not in the EU.Except dealing with Australia at least you are dealing in the same language and voltage.And avoiding all the EU customs rules and regulations.I had a very interesting conversation with Jantzen in Denmark about that and why it adds considerably to shipping costs to non EU customers.
 
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Lawrence001

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In which case, surely the aforementioned post about "OTL SS amps from Bakoon" is a complete red herring!?
Did anyone say that? I can just see statements like "if you like the OTL sound you probably should consider a Bakoon".
 

bencat

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Sorry my comment was not on the issues of importing equipment but more on there being no chance to hear the product before you commit a large amount of money to purchase . While importing is always possible but expensive the real issue iis once you have bought it your on your own any issues with your purchase is not going to dealt with quickly or cheaply .
 

Non-Smoking Man

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More on the OTL Mini Beast..
Thanks for the comments to date - useful and noted.
Currently I am driving a pair of Mark Audio Pensils with it, and though not especially efficient they dont have a crossover to cope with. 4 watts isnt ideal but its what I had available at the time for the second system which was somewhat thrown together.
Its been a surprise. Its dead quiet for one thing and like everyone has said it is very open. I'm thinking of trying it out in the horn system now that Disarmament is keeping his 2a3 amp and going High Efficiency. I fancy it could do a job for me.

Jack
 
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hifinutt

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Ooh lovely .absolutely loved the frugahorn and would love to hear the pensil . Wonder how much they differ from the sibelius
 

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These were my findings with the Big Brother:

  1. One amp worked perfectly from switch on, the other was blowing fuses after 5 mins. Tracing this to a hot-running resistor meant the only cause of excess current could be 2 Zener diodes fitted the wrong way round or failure of those diodes. The diodes were fitted correctly and when I switched on with a multimeter connected across them it was easy to pick up that they were failing once warm, i.e after around 4-5mins.
  2. As supplied and according to the circuit diagram, the metal-chassis amp has no safety earth connection. This is not only highly dangerous but also illegal in the E.U. On testing the amp there is no difference in hum with the chassis connected to safety earth, so it's even more strange the amp is supplied in this way. Of course, if the amp hummed with other equipment connected to it, then I would implement an earth lift or similar arrangement but so far no hum has been apparent.
3. And there's another safety / reliability issue. Switch on surge or failure of the HT fuses means 500v is applied to 400v rated caps and 400v to 350v rated caps. These caps should all be rated at 500v for long term reliability /safety.
And btw definitely not enough juice to drive Tannoy Canterburys
 

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