valve frequency responce

jwoodaudio · Post by **jwoodaudio** » Mon Dec 17, 2012 8:52 pm

whats the best frequency response any of you have had from a valve amp?

pre65 · Post by **pre65** » Mon Dec 17, 2012 9:12 pm

jwoodaudio wrote:whats the best frequency response any of you have had from a valve amp?

Good question that.

Does it matter ?

jwoodaudio · Post by **jwoodaudio** » Mon Dec 17, 2012 9:23 pm

matters alot. lets say you have a valve amp that only delivers 30 to 200 cyles your only goin to get bass coming out of the amp,

Post by **Nick** » Mon Dec 17, 2012 9:30 pm

I would say it depends on the type of amp, typical SET, I would aim for -3dB 10hz to 40kHz depending on valve, but I would not expect full power at that bandwidth. Active loaded cathode follower buffer will go up to 1Mhz or so, I gave up looking above that.

steve s · Post by **steve s** » Mon Dec 17, 2012 9:56 pm

jwoodaudio wrote:whats the best frequency response any of you have had from a valve amp?

The best for me is from 25 hz up to about 13.5 kHz ... as thats all I can hear
from a more sensible viewpoint, the mullard designs of the late 50's always measured well assuming the ironware was up to the job.

Paul Barker · Post by **Paul Barker** » Mon Dec 17, 2012 10:03 pm

If you took the Williamson spec literally you think any modern amp very poor at bass on account of OPT inductance (lack of).

No doubt this que's J Wood to give us the spec of his product?

pre65 · Post by **pre65** » Mon Dec 17, 2012 10:04 pm

jwoodaudio wrote:matters alot. lets say you have a valve amp that only delivers 30 to 200 cyles your only goin to get bass coming out of the amp,

Yes, of course.

What I meant was, if one builds a valve amp and the resultant sound pleases, does it matter ? Most of us would not be able to measure the frequency response anyway.

As was said when customers asked the power output of the worlds best car--it's adequate.

jwoodaudio · Post by **jwoodaudio** » Mon Dec 17, 2012 10:17 pm

what about the higher harmonics that alter the lower frequency's , i know most people cant hear above 15k but lets say i wind a transformer that rolls off at 15k and then i also wind one that rolls off at 70k no matter how good or bad your ears are you will be able to hear it,
Is there anyone near by to nottingham?

my overall question is how good are modern day valve amps, id like to compare mine to one side by side

Post by **Nick** » Mon Dec 17, 2012 10:31 pm

What I meant was, if one builds a valve amp and the resultant sound pleases, does it matter ? Most of us would not be able to measure the frequency response anyway.

As was said when customers asked the power output of the worlds best car--it's adequate.

Yep, but how do you know its adequate?

People differ, but I have never found measuring a amp has made it sound worst, and it has often allowed me to make it better next time.

IslandPink · Post by **IslandPink** » Mon Dec 17, 2012 11:24 pm

jwoodaudio wrote:what about the higher harmonics that alter the lower frequency's , i know most people cant hear above 15k but lets say i wind a transformer that rolls off at 15k and then i also wind one that rolls off at 70k no matter how good or bad your ears are you will be able to hear it

I think this certainly correct .
I would think that Dave Slagle ( transformer winder ) would tell you that output transformers need to go to 50-70kHz at -3dB, but also it would matter whether they were sloping off smoothly, or whether they were ringing as they died-off at the top end, and that would be audible.

I know if you design a driver stage for a DHT that has no slew limiting at 20kHz, it would be adequate, but a bit muddy in the treble and lacking micro-dynamics, but if it had no slew-limiting up to 50 or 60kHz, it would have tone and 'sparkle' in the HF .

jwoodaudio · Post by **jwoodaudio** » Tue Dec 18, 2012 11:40 am

we wind all our trasnformers in house so far we have managed to get one producing 1 to 205k and it sounds fanstastic

pre65 · Post by **pre65** » Tue Dec 18, 2012 11:48 am

jwoodaudio wrote:we wind all our trasnformers in house so far we have managed to get one producing 1 to 205k and it sounds fanstastic

I salute you sir, that is a very good achievement.

steve s · Post by **steve s** » Tue Dec 18, 2012 12:23 pm

Do you sell the transformers ? UK made high quality transformers are in short supply. Sowters are good, but thicken the bass up a fraction in my limited experence I would be very happy to try a pair of yours. Could compare them to the tributes I use.

jwoodaudio · Post by **jwoodaudio** » Tue Dec 18, 2012 3:12 pm

steve s wrote:Do you sell the transformers ? UK made high quality transformers are in short supply. Sowters are good, but thicken the bass up a fraction in my limited experence I would be very happy to try a pair of yours. Could compare them to the tributes I use.

No sorry we dont, our transformers are made strictly for our amps and designed for each unit, thats one of the main reason the amps sound like they do.
We also do a valve preamp which does dc to 14mhz we couldnt test further as the signal generator starting rolling off.

Post by **Nick** » Tue Dec 18, 2012 4:04 pm

Paul is starting to look right.

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valve frequency responce

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