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Author Topic: What?! Another headphone amp kit?! Smack me!  (Read 25731 times)

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Offline Jim R.

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Re: What?! Another headphone amp kit?! Smack me!
« Reply #45 on: August 23, 2011, 03:44:16 PM »
So, how did the meet go and how did the Smack fare?  And the new s.e.x.?

-- Jim
Jim Rebman -- recovering audiophile

Equitech balanced power; uRendu, USB processor -> Musette DAC -> 5670 tube buffer -> Finale Audio F138 FFX -> Cain and Cain Abbys near-field).

s.e.x. 2.1 under construction.  Want list: Stereomour II

All ICs homemade (speaker and power next)

Offline Doc B.

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Re: What?! Another headphone amp kit?! Smack me!
« Reply #46 on: August 24, 2011, 08:21:34 AM »
It went very well. It seemed like different people had different faves depending upon their taste and the cans they were using. The Smack accounted for itself very well with people giving positive comments using everything from low impedance AKGs and Sennheisers to HD800s and even power hungry LCD-2s. Another LCD-2 owner preferred the power output of the S.E.X. with the LCD-2. I wish I had made up an adapter to run the LCD-2s with the Paramounts.

My initial impression of the Smack vs. Crack with high impedance cans here at BHQ was that the Crack was better on the bottom end, with tighter bass. At the meet where there is a bit more background noise and the Smack had some more play time on the iron there did not seem to be as big a difference in the bass region and the single gain stage voltage amp and transformer combo was really nice in the mids and top end. For me the "balanced" (floating left and right signal cold) vs. single ended (common signal cold tied to ground) comparison with the Smack was a dramatic difference and probably the day's most impressive demonstration of the capabilities of our amps. Folks seemed kind of split on the Crack vs. the Smack, with the guys who had higher dollar cans seeming to like the Smack a little better and guys who were just getting into headphones and having medium priced cans appreciating that the Crack was very close sonically for about half the money.

One cool thing about these meets is that unlike big trade shows where it takes several weeks to find out if you influenced any sales with your presence, we have had several folks buy headphone amps based upon listening at the meet and reading the results posted on head-fi, with all three amp models selling as a result. I suppose folks want to hear there is a clear winner here, but that's exactly why we make three different amps. Different cans, different tastes.
Dan "Doc B." Schmalle
President For Life
Bottlehead Corp.

Offline xcortes

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Xavier Cortes

Offline xcortes

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Re: What?! Another headphone amp kit?! Smack me!
« Reply #48 on: August 24, 2011, 08:47:37 AM »
So it looks like the Smack is a winner. Have you compared it with your Big Headphone Amp? Maybe I don't want to know!

If I ever finish building my Crack, rebuilding my Parabees for K1K use AND building my 437A preamp/headphone amp (oh, and installing the three pairs of soft start upgrades!) I'll have to order a Smack and recable my Sonys for balanced!
Xavier Cortes

Offline Jim R.

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Re: What?! Another headphone amp kit?! Smack me!
« Reply #49 on: August 29, 2011, 11:29:54 AM »
Xavier,

Thanks for the link to the impressions thread on HF.  I saw that there was one guy there who likked the smack with the AKG K601s, which is exactly what I would intend to do with mine, including a balanced rewiring of the 601s.

Dan, have you settled on a pf cap value yet?  Earlier in the thread you mention that you started with 3.3 and then went to 13, but wonder if this has changed since.  Also, what kind of voltage rating does this cap need?

I'm really glad to see the movvee towards a balanced headphone amp!

-- Jim
Jim Rebman -- recovering audiophile

Equitech balanced power; uRendu, USB processor -> Musette DAC -> 5670 tube buffer -> Finale Audio F138 FFX -> Cain and Cain Abbys near-field).

s.e.x. 2.1 under construction.  Want list: Stereomour II

All ICs homemade (speaker and power next)

Offline Paul Joppa

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Re: What?! Another headphone amp kit?! Smack me!
« Reply #50 on: August 29, 2011, 11:36:28 AM »
10uF / 250v is now standard.
Paul Joppa

Offline Jim R.

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Re: What?! Another headphone amp kit?! Smack me!
« Reply #51 on: August 29, 2011, 11:43:59 AM »
Thanks, Paul.  Hope you're doing ok.

-- Jim
Jim Rebman -- recovering audiophile

Equitech balanced power; uRendu, USB processor -> Musette DAC -> 5670 tube buffer -> Finale Audio F138 FFX -> Cain and Cain Abbys near-field).

s.e.x. 2.1 under construction.  Want list: Stereomour II

All ICs homemade (speaker and power next)

Offline Frihed89

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Re: What?! Another headphone amp kit?! Smack me!
« Reply #52 on: September 04, 2011, 04:01:30 AM »
What is the measured power out and current at the different impedance settings?

Thanks

Offline Paul Joppa

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Re: What?! Another headphone amp kit?! Smack me!
« Reply #53 on: September 05, 2011, 10:00:00 AM »
I don't have a Smack here so all I can offer is the theoretical values based on the plate curves and transformer ratio, assuming the load is matched to the nominal impedance setting:


 16 ohms  1.8 volts 112mA
 32 ohms  2.5 volts  80mA
 64 ohms  3.6 volts  56mA
128 ohms  5.0 volts  40mA


These are RMS voltages and currents. Some 6 to 10dB headroom above the IHF standard. The maximum output power is about 200mW.
Paul Joppa

Offline Doc B.

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Re: What?! Another headphone amp kit?! Smack me!
« Reply #54 on: September 06, 2011, 06:58:43 AM »
Want to give a status update to those who have pre-ordered. We haven't forgotten about you! As happens sometimes the process of getting the parts together is taking a little longer than expected. Our laser cutter has been swamped and it took a while for him to get us a quote so we could order the chassis plates. They are now in the production queue as are the transformers. Should be a couple/three weeks and we will have some kits to ship.
Dan "Doc B." Schmalle
President For Life
Bottlehead Corp.

Offline tdogzthmn

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Re: What?! Another headphone amp kit?! Smack me!
« Reply #55 on: September 07, 2011, 06:01:24 PM »
I have several headphones of various impedances so I wondering if the Smack will give me better results across the board since it is more capable with lower impedance cans than the Crack.  It looks like the highest setting is for 128 ohms which I would think is what you would set it on when using 300 ohm HD600. 

Offline keto

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Re: What?! Another headphone amp kit?! Smack me!
« Reply #56 on: September 17, 2011, 09:42:49 AM »
PJ posted these outputs for the Smack:

 16 ohms  1.8 volts 112mA
 32 ohms  2.5 volts  80mA
 64 ohms  3.6 volts  56mA
128 ohms  5.0 volts  40mA

which would lead to....

256 ohms 7.2 volts 28mA
512 ohms 10.0 volts 20mA

So (smack me if I'm wrong) wouldn't this make an awesome preamp, with 8K:600 OPT's??????
Tom Jones

Offline Doc B.

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Re: What?! Another headphone amp kit?! Smack me!
« Reply #57 on: September 17, 2011, 09:58:37 AM »
To tdog,

We're tweaking up Crack, S.E.X. 2.1 and Smack for RMAF right now. As we fine tune them (experimenting with more current in the Crack and we finally got around to putting a C4S in the S.E.X. 2.1), they get closer to each other sonically. That said, the single gain stage and the shunt regulator seem to give the Smack the advantage in resolution over the other amps. Where it comes up a bit short with respect to the other two amps is in gain. We were running a very marginal level from our DAC this week and we had to turn the Smack up all the way while the other two amps had some room left on the volume knob. With normal output levels it's not a problem. We adjusted the DAC output up a just few dB and that allowed the Smack to show its stuff with some room left to turn the knob- very quick and dynamic with anything from 32 ohm cans on up.

to Keto,

My inclination would be to try the circuit as a preamp without any transformer. The output impedance would still be OK with a lot of amps - though my own search has been for a preamp tube that will have an output impedance down under 1K ohm, without a transformer. My opinion is based upon trying the transformer output circuit as a preamp vs. a low output impedance tube with no transformer, last spring.
Dan "Doc B." Schmalle
President For Life
Bottlehead Corp.

Offline Armaegis

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Re: What?! Another headphone amp kit?! Smack me!
« Reply #58 on: September 29, 2011, 04:49:24 PM »
Want to give a status update to those who have pre-ordered. We haven't forgotten about you! As happens sometimes the process of getting the parts together is taking a little longer than expected. Our laser cutter has been swamped and it took a while for him to get us a quote so we could order the chassis plates. They are now in the production queue as are the transformers. Should be a couple/three weeks and we will have some kits to ship.

Any status update on the Smack kits?

Offline Doc B.

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Re: What?! Another headphone amp kit?! Smack me!
« Reply #59 on: September 30, 2011, 04:39:49 AM »
Iron has just arrived. Now just waiting for the chassis plates to turn out a quick final prototype for pics for the manual and then we can start to ship.
Dan "Doc B." Schmalle
President For Life
Bottlehead Corp.