Considering BHK 250 power to match my Signature Pre - Question on speaker efficiency..is the 250 a good move for me?


#1

Hi
Currently awaiting my Signature Pre arriving soon and considering the matching 250 power amp.
I have a DS dac as well.

Sounds a great match on paper, but I currently use a 300B SET power amp (8 or 9 watts output depending on how you measure it) and my speakers are 94/95dB efficient.

Gain structure/ volume is great with the SET amp, it gets too loud with volume knob at 9 o’clock.

My concern is that with the BHK 250 Power amp in the system, my high efficiency speakers will make for a system that is just TOO loud, with not enough granularity in setting volume.

Am I thinking along the wrong lines here, would the BHK power amp be a good fit in my system?
Any wisdom appreciated. :slight_smile:

Thanks.


#2

If it 'aint broke don’t try to fix it. Stick with the 300B SET power amp.


#3

I guess the question is, what is your motivation to consider another amp? Is there something missing with the 300B SET in place? Or, are you merely anticipating a “match made in Heaven” with the BHK Pre and Power Amp?

My suggestion for you would be to sit tight, get the pre-amp in place and then assess. If there is still a void, come back and tell us about it. With those high efficiency speakers, your 8 or 9 tube watts is plenty, especially considering your listening level preferences, gleaned from your 9 o’clock max position on the attenuator.


#4

"I guess the question is, what is your motivation to consider another amp? "

That’s a very good question.

I think the combination of a 300B valve going pop (ouch) and the anticipation of the BHK Pre coming did swing my thoughts in a particular direction.
The “match made in heaven” mindset had kicked in if I was honest.

Bodric,
I hear you.
Aside the cost of entry with valves and these amps…it ain’t broke. :slight_smile:

Problem solved,
Bought a new set of 300B power tubes, just part of the game (and price of ownership) with these amps.
Had the valves for a couple of years, really should have been thinking about a new set anyway. (unfortunately!)

Thanks for the food for thought guys.

Think I just needed a bit of reflection


#5

What amp and what 300Bs did you buy? And what speakers?

I have yet to see a 300B fail. This makes sense as their average lifespan is 40,000 hours. (As I am certain you know, they were developed by Bell Laboratories to meet the challenges of underwater transatlantic cable use, which obviously requires a robust and long life.)


#6

I learned something new.


#7

Me too!


#8

Depends on what valve your taking about?

The 300B was invented by Western Electric in 1938 to amplify telephone signals and the WE version of the 300B has a bit of a religious following.
Working examples from 1940’s but they are unobtanium and not many of us are happy to part with a kidney for our music!

My valves were KR Audio 300B balloon glass tubes.
Rated lifetime is 10,000 hrs. (13 1/2 months), got a couple of years out them so I don’t feel too put out.
Nature of the beast unfortunately.

Amp is one you can’t buy commercially, built to my own spec.
It’s designer is a British version of Ted Smith and designed this:
http://www.the-ear.net/review-hardware/music-first-audio-reference-phono-stage-mm-phono-stage

His “Jnr” version of the phonostage ( or “Baby Reference”) got a mention over on Steve Hoffman’s forum:

Speakers are again, bespoke.
Nick Gotham, my amps designer, runs a UK based forum “Audio Talk”, and a speaker designer over there took a collaborative project with the guys there to design his ‘Ultimate’ speaker.
He’s good friends with Nick, and collaborated with him on it too.
Info here:
http://www.audio-talk.co.uk/phpBB3/viewtopic.php?t=3578

I asked Nick to design a 300B SET that didn’t have the traditional traps of SET amps.
His response was to undertake a project which (in his words) would see how far he could go with taking 300B and surrounding it with solid state.
Another collaborative effort of the guys on the forum to bump heads and see how they could help.
Outcome was ‘better than commercial’ solid state power regulation, which combined with very overspecced output transformers and clever circuit design…led to a rather good amp.

Doesn’t sound like any other SET amp I’ve heard…drive dynamics and scale alongside the more traditional liquid midrange and in the room imaging.
As I said earlier, it certainly ain’t broke - apart from one of the output 300B tubes!

Ironically given the talk earlier about longevity of valves, it’s a set of Western Electrics I’m replacing the KRs with.

Fingers crossed for more than a couple of years use out em. :slight_smile:


#9

Very cool! Thanks for the description. Neat stuff.

I have toyed with buying a pair of Takatsuki TA-300Bs for my WA5 headphone amp.

I assume given your report of limited longevity you are leaving the amps on 24/7, yes? If so, I am not aware of anyone else who does this with a tube amp. Intriguing.


#10

Hi Elk,

No,
For me, I’d not be comfortable leaving a tube amp on 24/7…but I hear you about switching on the tubes from cold potentially impacting tube life?

I feel better about it knowing Nick built a ‘soft start’ circuit to the amp, on switch-on it takes 20 secs or so for the DHT heater to get to full voltage, so lessens wear on the tubes from potential voltage spikes on switch on.
There’s some very clever hybrid solid state/tube voltage regulation in there too, so that’s good.
As Nick put it, he designed the amp to “go easy” on tubes.

Just think I’ve been unlucky with that set of 300B’s!

The Tak’s are supposed to sound wonderful, other tubes like the Elrogs and (Hopefully) my new WE’s are good alternatives for 300Bs that can get the best out of your kit.

Just depends on your taste of course. :slight_smile:


#11

This sounds like an amazing amp.

I have not compared 300Bs in any real sense. The detailed reviews of the sound and construction of the various offerings are great fun to read.


#12

Just to close my thread off here,
The Western electric 300Bs came yesterday so have a working amp again.

I say “working”…these valves live up to the reputation, wow.
Take 300Hrs to burn in to get final sound, but already hearing (by far) the best sound I’ve heard with my system so far.

And I have a BHK Pre coming this week. :slight_smile:
Happy days.

Be sticking with this, no BHK 250 for me.

Thanks guys for the input.


#13

It is wonderfully satisfying to have spent that kind of money and it was worth it. :slight_smile: