Crack vs Woo WA3

[Guy 13]

Hi all.
Why the Crack is not recommended for 35 Ohms headphones
and the WOO WA3 (Similar topology) claim that it can drive headphones from 30-600 Ohms.
Would WOO exaggerate their claim or simply lie?

Guy 13

[Doc B.]

If you need and answer about Jack Woo's amps the only reasonable solution is to ask Jack Woo the question. Asking us to answer this is trolling, even if not intended as such. Out of respect for Jack Bottlehead Corporation will not speculate about his designs or specifications.

[Guy 13]

If you need and answer about Jack Woo's amps the only reasonable solution is to ask Jack Woo the question. Asking us to answer this is trolling, even if not intended as such. Out of respect for Jack Bottlehead Corporation will not speculate about his designs or specifications.

Hi Doc.
Let me re-phrase my question.
Can you make/modify the Crack so it can drive headphones down to 35 Ohms
(Read 60 Ohms for the HD-570)?
The reason I ask, is because I own two pairs of Sennheiser (HD-650 + HD-570)
and I like both of them, because both of them have their strength.
The HD-570 are brighter and the HD-650 are darker.
I would like to use both of them on my Crack that sounds very good.
 
Guy 13

[Loon]

1. Add output transformer
2. Try a compatible tube with high mutual conductance in place of the 6080 (eg 7802).  This should slightly reduce the output impedance.
3. Buy a SEX or Mainline and sell your Crack
Naïfurne

[Guy 13]

1. Add output transformer
2. Try a compatible tube with high mutual conductance in place of the 6080 (eg 7802).  This should slightly reduce the output impedance.
3. Buy a SEX or Mainline and sell your Crack
Naïfurne

Hi.
1. You are suggesting an output transformer,
how about giving me/us some directions as where to buy, make, model.
Since you are suggesting that option, maybe you have experience with that and can make my/our life easier, please keep in mind that not everybody is as resourceful as you are.
2. I have a few names of tube suppliers, but maybe you can give me/us a make that you prefer
and from whom you suggest we buy. That would make my/our life easier. Yes, no, maybe ? ? ?
3. Buy SEX or Mainline with what money, maybe you want to give me the money.
The Crack + assembly by w third party + HD-650 that blew my budget.
I am stuck with my Crack + HD-650 combo.
I am looking for a cheap solution and keep in mind that I am living on planet Vietnam and here it's not what you want, it's what they have and what they have is not what you really want. Vietnam is the country of compromise when it comes to electronics...
Any other suggestions ? ? ?

Guy 13
 

[Loon]

Hi there

1.  I don't know enough yet how to add an output transformer to the circuit.  Would like to find out.
2. The 7802 is quite a rare and expensive tube.  I have an new, unused pair of Tung Sol 7802WB tubes that cost me $200.00 from an eBay seller.  They were his last pair.  I don't know where you could buy any others. 
3. This is the option I would most strongly recommend if you want to drive headphones of a lower impedance.  Sorry.  The Crack just isn't designed for these.

Cheers

Nathan

[Guy 13]

Hi there

1.  I don't know enough yet how to add an output transformer to the circuit.  Would like to find out.
2. The 7802 is quite a rare and expensive tube.  I have an new, unused pair of Tung Sol 7802WB tubes that cost me $200.00 from an eBay seller.  They were his last pair.  I don't know where you could buy any others. 
3. This is the option I would most strongly recommend if you want to drive headphones of a lower impedance.  Sorry.  The Crack just isn't designed for these.

Cheers

Nathan

Hi Loon.
If I had the same income as you or as I had when I was 40 years old in Canada,
I would immediately buy something else.
That's what I did so many times in the past, but today...
It's a completely different story, therefore, thanks for the suggestions,
but I will keep my Crack + HD-650 unless someone wants to buy it the same price I paid,
but I am realistic and I know it will never happen.
I will use my Sennheiser HD-570 (60 Ohms) with my iPod and my Sony mini receiver.

Guy 13

[JamieMcC]

My ATH W1000X at 42ohms sounded great out of the Crack I was quiet surprised when I tried them. I could certainly enjoy listening with them.

[Loon]

Exactly.  If it sounds good to you, that's all that matters.  It's about sound in practice, not theory or some "ideal" matching.

[Guy 13]

Hi all.
O.K. I will try my 60 Ohms headphones
and see/ear if I like the sound.
I hope on long term, nothing (Bad) will happen to the 6080/6AS7G ?

Guy 13

[Loon]

All safe

[Guy 13]

All safe

Hi Loon.
I am a member for life of the Friday 13 lucky guy.

Guy 13
Born on a Friday 13, yes, for real.

[kgoss]

You would certainly change the sound character of your Crack if you added output transformers and without a lot of trial and error you would end up with something worse. The Crack is an OTL amp which let's you hear the output of the tube without a transformer in the way. There are always trade offs and with an OTL amp you are trading the ability to match low impedance loads for the ability to listen without a transformer adding its color to the signal.

Try your low impedance phones with the Crack. The bass might not be the best you have heard from them but it won't hurt anything to try. You might well like the pairing and after all that's the only thing that matters.

Ken

[Guy 13]

You would certainly change the sound character of your Crack if you added output transformers and without a lot of trial and error you would end up with something worse. The Crack is an OTL amp which let's you hear the output of the tube without a transformer in the way. There are always trade offs and with an OTL amp you are trading the ability to match low impedance loads for the ability to listen without a transformer adding its color to the signal.

Try your low impedance phones with the Crack. The bass might not be the best you have heard from them but it won't hurt anything to try. You might well like the pairing and after all that's the only thing that matters.

Ken

Hi Ken.
The reason why I choose a OTL headphone amplifier,
it's because I believe it's superior to output transformer amplifier.
As a matter of fact I choose between the Schiit Valhalla,
the WOO WA3 and the Crack, all of them OTL.
The Schiit Valhalla is a PVB circluit and runs very hot, the WOO as three tubes and look like a German tank and then the Crack was what I wanted.
Yesterday, I did about an hour of listening with my Sennheiser HD-570 (60 Ohms) headphones and here are my conclusions:
The bass is not tight, it lack impact, it's muddy, it's simply not natural like the HD-650.
The mids are relatively good, but at times, they are a little fuzzy,
now the highs are good, very good, much better than the HD-650,
but over all, the HD-650 is better, therfore I will be using more often my
HD-650 and keep my HD-570 for my iPod and my mini Sony receiver.

Guy 13
 

[Loquah]

Hi Guy,

An assembled Crack will generally sell for more than the kit. If you built the Crack yourself you can probably recoup your original outlay and then some. I say this because I've now owned and thoroughly compared (over on Head-fi) the Crack, SEX and Mainline, and would highly recommend upgrading to the SEX in order to drive both your headphones to even better performance than the Crack.

The SEX sounds different to the Crack, but personally I find it more resolving and with a larger soundstage. It's a worthy upgrade in sound, but also versatility in driving any impedance headphone.