John Curl's Blowtorch preamplifier

[john curl]

And WHO is sneaking around for an attack on Charles?

 

[john curl]

Wow, just hearing differences is just not enough for most people. You have to notice them every day, on every recording, on every medium.
It is just like: ' If you used an automobile exclusively for going to the store and back, would you want to purchase a Ferrari?'
Or: ' If you sit in the back seat of one of two autos, while sitting on a blanket. I bet you can't tell a Mercury from a Mercedes.'
Well DUH!

 

[SY]

Some here act as if serious audio designers, like Charles or 'little old me' are either money grubbing charlatans

John, if you're money-grubbing, you're as bad at grubbing as I am.

 

[john curl]

Thank you, SY. If this is 'money grubbing' then I would hate to know the alternative. At least, YOU know my actual physical condition.

 

[SY]

About like mine. Like you, I've had a very successful career making other people rich.

 

[Charles Hansen]

What used to catch me out for few years a long while ago was listening immediately after soldering something new. Whatever the reasons for this (and I have my own theories) it always adversely affects the sound for a while, sometimes 30 mins or so, but frequently for longer.

Here's a tip that will save you countless hours of time. After you have soldered your circuit (or moved a cable or anything that disrupts your system), simply play the "sweep" track from our Ayre IBE CD or the Cardas LP (if you are a phono kind of guy). This will get the system 90% of the way back to normal in one minute. We couldn't get anything done without it.

 

[Charles Hansen]

Just curious, which way they sounded better?

Tight against the PCB.

 

[Charles Hansen]

I take it that the DUTs were all constantly in their "ON" position, so there were no identifiable noises made by them.

Yes, plus we didn't need a power supply to energize the relays.

The first is: how "golden-eared" does the listener have to be to identify the kinds of differences you heard?

There is no such thing as a "golden ear". Only practice and a willingness to keep an open mind. For years I would let other do many of the listening tests because I didn't trust my own ears. Then for many years I wouldn't even bother with some listening tests because I "knew" that the changes I could have made couldn't have *possibly* made any difference. Oh, how wrong I was!

The second is: how familiar with the system does the listener have to be to identify the kinds of differences you heard? For example, if someone walked in off the street and only had the half-hour or so of familiarization you described, would that be enough?

Not even close. I think you need to listen to a system daily for an hour or two for around a month before you would be familiar enough with it to hear small changes.

The third is: How high must the quality of the overall system be to identify the kinds of differences you heard? I'm sure you listened on a very good system. Would those differences have been quite identifiable in a system whose total cost was 1/4 to 1/2 that of the system you used (still probably a quite good system).

Far more important than the price or "quality" of the system is how well it is set up. Spend $50 and get Jim Smith's book "Get Better Sound". Then spend a month or two trying things out. After six months you will be able to get your system very dialed in, *if* you put some time into it every day.

Start by orienting the AC polarity on each component. Then float the entire system with "cheater" plugs. Then raise all of the cables off the floor with wood blocks. Then spend a few hours fine tuning the position of your loudspeakers. These four things will reap huge dividends.

The last is the following: let's say you did such a listening test 10 days in a row, but on each day you listened to only one of two DUTs. Perhaps the switch and one of the middle-range relays from your testing. During the night, without your knowledge, you assitant secretly swapped or did not swap the DUT. With what degeee of success do you think you could identify the DUT each day?

100%.

 

[john curl]

You tell 'em, Charles! You have more 'guts' than I do.

 

[alansawyer]

Tight against the PCB.

I'm curious as to why you needed to cut the leads. Do you think the sound would have been different had you soldered them close to PCB and left leads uncut? That way you could have reused them later.

 

[Charles Hansen]

The PCB was stacked above another PCB quite closely.

 

[maxpou]

Start by orienting the AC polarity on each component.

Hi M.Hansen,
do you want explain to me please? Thank you Maxpou

 

[GK]

You connect the signal wire to ground and the ground shield to the signal input. Makes a huge difference to the sound.

 

[GK]

Since this thread is all about keeping an "open mind" I wonder why on earth Feng Shui has never caught on in amplifier design. Looking back at those inside pictures of the Blowtorch at the begining of this thread makes me gasp.
That thingie has seriously negative ch'i.

 

[alansawyer]

The PCB was stacked above another PCB quite closely.

I'm not sure I understand. Didn't you say you swapped the capacitors for alternate brands?

It doesn't seem to make any sense that you had to dismantle a board and remove caps in order to do tests.

Surely you would have forgotten the sound by the time all this changeover work was done?

 

[alansawyer]

I have boxes and boxes of supposedly wonderful-sounding parts collected over the years which I will never use again, but that is all part of development trials, unfortunately.

Since you will "never use them again" send them over and I will try to recycle these parts.

 

[analog_sa]

Surely you would have forgotten the sound by the time all this changeover work was done?

Very amusing. If one "forgets" sound over a short period of time, what is the purpose of any imrovements? Just to entertain friends in AB comparisons?

 

[jacco vermeulen]

to

to Mr Danyuk :

In Audio City no one seems to be credible without documents.

It is very likely that Mr Hansen also measured negligible distortion levels of various relays, yet he favors oldfashioned hard labor switching, the explanation would be of interest.
Mr Hansen doesn't seem like the cosmos floating type, even if he prefers to build space shuttles instead of ordinary Porsche cars for the commoners.

 

[SY]

Start by orienting the AC polarity on each component. Then float the entire system with "cheater" plugs.

You're advocating lifting the safety ground??? Hope you have a good lawyer.

This is an extremely unsafe practice.

 

[scott wurcer]

or the Cardas LP (if you are a phono kind of guy).

From the Cardas website:

>These are the degaussing tracks 2a, 2b and 2c. Simply play one of these tracks through your system at a low, normal level and it will degauss the cartridge and the rest of the system, plus clean the stylus ultrasonically. <

Please describe the physics of degaussing by playing an LP. Again not some anececdotal listening experience, but a verifiable claim of measurable physical change. I like the "and the rest of the system".