Crack;Bottlehead OTL - Page 98

Yep, I found the Harrisons with a quick search. Thanks!

BTW, I don't mean to sound whiney about the gain issue. The Crack + Speedball flat-out rocks the HD-650. Everyone who's posted about what a great combo this is has been 100% right all of these years.

Quote:

Originally Posted by dpippel 

Yep, I found the Harrisons with a quick search. Thanks!

 

BTW, I don't mean to sound whiney about the gain issue. The Crack + Speedball flat-out rocks the HD-650. Everyone who's posted about what a great combo this is has been 100% right all of these years.

What's your source output level? 

Quote:

Originally Posted by Doc B. 

What's your source output level? 

Hi Doc! I'm feeding the Crack with a Channel Islands Audio VDA-1 DAC and can't find the specs for it any longer. It's successor, the VDA-2, is rated at 2.25 vRMS. I will assume that the VDA-1 is the same.

EDIT: The VDA-1 outputs 2.4 vRMS.

Quote:

Originally Posted by Draygonn 


http://www.amazon.com/Harrison-Labs-Line-Level-Attenuator/dp/B0006N41B0/ref=sr_1_1?s=electronics&ie=UTF8&qid=1360288707&sr=1-1

They are one-way. I had them connected improperly the first time and had a weird echo effect with some tunes.

So do these attenuators go in-line on the inputs of the Crack?

Quote:

Originally Posted by BmWr75 

 

So do these attenuators go in-line on the inputs of the Crack?

Yes.

So what caps are you guys upgrading to now that the Aeon ones are gone (they are gone right?)

Quote:

Originally Posted by dpippel 

 

Hi Doc! I'm feeding the Crack with a Channel Islands Audio VDA-1 DAC and can't find the specs for it any longer. It's successor, the VDA-2, is rated at 2.25 vRMS. I will assume that the VDA-1 is the same.

 

EDIT: The VDA-1 outputs 2.4 vRMS.

Yeah that would be part of the issue then. Way back in the olden days there were things called standards. This is black art stuff now, no one understands them in the 21st century. But back when these strange things called CDs first came out the people who made players for them said the output level should be 2V. Pretty soon others figured out that if their player was louder, people thought it sounded better. And so output levels kept rising. IIRC one of the craziest was the Art Audio DIO which had like 7V output. To further confound this, the standard for phono playback is 0.5V. And back in the day the standard for cassette tape playback was something like 150mV!

Also, bear in mind that Crack has to be able to work with 600 ohm cans too. They will usually require the volume knob level to be set higher than lower impedance cans. So between the differences in source output levels and headphone sensitivity, volume control settings are really a moving target. But hey, that's why the knob turns.

Aye - since I use a computer as the primary source (feeding into the D100), I use the pre-amp there to attenuate - the Crack can get loud with my HD-600s. :)

But what a great pairing. 

Quote:

Originally Posted by Doc B. 

Yeah that would be part of the issue then. Way back in the olden days there were things called standards. This is black art stuff now, no one understands them in the 21st century. But back when these strange things called CDs first came out the people who made players for them said the output level should be 2V. Pretty soon others figured out that if their player was louder, people thought it sounded better. And so output levels kept rising. IIRC one of the craziest was the Art Audio DIO which had like 7V output. To further confound this, the standard for phono playback is 0.5V. And back in the day the standard for cassette tape playback was something like 150mV!

 

Also, bear in mind that Crack has to be able to work with 600 ohm cans too. They will usually require the volume knob level to be set higher than lower impedance cans. So between the differences in source output levels and headphone sensitivity, volume control settings are really a moving target. But hey, that's why the knob turns.

 

Thanks for the feedback Doc. While I agree that you can't possibly accommodate all possible scenarios, it still seems to me that perhaps the design of the Crack might be a bit more forgiving in this respect. For example, I've recently spent quite a bit of time comparing other DACs to my VDA-1, including the Schiit Audio Bifrost and Modi, the HRT Music Streamer II, and the ODAC using the Schiit Asgard, Lyr, and Magni for amplification as well as the Matrix Audio M-Stage and and the Burson Soloist. All of the above mentioned DACs had line-level output so close to the VDA-1 that I rarely had to make a volume change when swapping them out, and when I did it was minimal. With that large a sampling of contemporary DACs, the 2.4 vRMS output of the VDA-1 seems to be well within the industry norm. My issue with the gain on the Crack and the HD-650 is that I'm barely getting the volume pot up to 1/6th of its range before it's too loud. Does that work? Surely, but I think that a more realistic gain level would allow me to move it up to 9:00 or even 10:00 for a 300 ohm load. That would leave plenty of headroom for higher impedance cans and it would also get the volume pot out of potential channel imbalance territory.

Of course I may be almost completely clueless too. This is just my two cents. As I've said I love love LOVE the way the Crack + Speedball sounds with my Senns. If this gain issue continues to be a problem for me I'll probably end up doing what others have done, get a pair of 12dB attenuators, and deal with it. Just wish I didn't have to go that route or incur the additional expense. If you have any alternative suggestions or can point me to any I'd be grateful.

Thanks for listening.

I'm chuckling because two weeks ago we had a long thread on the Bottlehead Forum a guy who said Crack didn't have enough gain. I just want to know which one of you guys is right?!!

Part fo the the reason the Crack sounds good is the simple direct coupled circuit. There are very few tube combos that will work for this and almost all have more gain, not less. So the best bet is to adjust the source level. If you can trim the output of your music server in the software, that is one solution. The in-line attenuators are another. And of course they are not rocket science, you can look online and find info about making a voltage divider that you could build into the input. Simplest thing to start with might be putting a 100K resistor between the input jack and the volume pot.

Quote:

Originally Posted by Doc B. 

I'm chuckling because two weeks ago we had a long thread on the Bottlehead Forum a guy who said Crack didn't have enough gain. I just want to know which one of you guys is right?!!

 

Why, I am, of course! 

Seriously though, thanks for the suggestions. Since I subscribe to the "purest path possible" line of thinking I'll probably just live with it as-is.

I have a Crack + Speedball with 100uF P-E film caps installed.  It is fed by an AppleTV playing lossless files through an Emotiva X-DAC1.  The main cans I use with it are Beyerdynamic T-70s.

The same source feeds a PrimaLuna Dialogue Two tube integrated amp and ADS L1230 speakers.

The headphone set up absolutely slays the speaker set up.  I can switch back and forth between the two easily.  The results are not even close and I have the L1230s set up decently in the listening room.

The Crack is amazing with some certain cans and good source material.

I received a Crack with Speedball from a fellow hf member, and it seems it did not travel well.

I was going to post this on the BH forums, but my account has not been verified and I woudl like to start working on a resolution.

The problem is that the right channels does not play. The problem is not with the small signal tube, but I will not have a spare power tube to test with until Thursday.

Looking at the undersides of the amp, the top arrow hows a loose connection. Tapping this will cause the LED's in the SB to turn off/on.

The second arrows shows a pair of LED's that will not turn on, I think it is safe to assume this relates to the dead channel.

I do not have any schematics or assembly manuals, not sure if these are available online.

Any advise woudl be appreciated.

(I had to remove  the image else the entire post goes invisible. Imagine, if you will, an  elegant and graceful blue dashed arrow pointing to the cap near the RCA inputs while its equally graceful but slightly less elegant twin leads the intrepid viewer's vision to the LED's by the lower heat sink on the speed ball)

KP

Well, that was creepy, my post and its image disappeared after saving. If I edit the post it's all there, but after Submit it goes blank.

KP