[texendo]

I just replaced the stock WIMA 3.3uF output coupling caps with 2.2uF Jensen Copper PIOs.  The WIMAs have been in the unit for hundreds of hours, maybe a thousand, and the new Jensens have been on a Hagerman FryBaby burn in device for about two days.  Right off the bat, the Jensens are much smoother with what seems to be a more virile bass presence.  There may be a touch loss of upper end transparency with the new Jensens that could very well vanish with more burn in.

I've been under the impression (but I'm certainly no EE) that a smaller valued output cap might result in losses in the bottom end, but this certainly doesn't seem to be the case here.  Then I've read hear on the circles that someone else modded their Attraction DAC with 0.47uF Audio Consulting Silver PIOs and gained benefits in the upper and lower end.  Apparently my understanding of the effects of cap values is seriously flawed.

I'm interested in using some V-cap teflons as the output caps and want to know how low I can go.  A pair of 3.3uF caps is about a grand, and a pair of 0.47uF caps is about $280, so there's a BIG difference in price.

Also, why do the smaller value 0.47uF Audio Consulting caps cost twice as much as the larger valued 3.3uf caps?

Thanks in advance for any useful input.

[kyrill]

equally well but not that ridiculous priced is the Sonicap PLATINUM
1uf zie www.soniccraft.com

to go better than that i am afraid is beyond the Altman Dac

As good as the dac is on timbre and tone, those supercaps are more able to pass thru
good luck

[tanchiro58]

Texendo,

I have modded both Altmann Attraction DAC (coupling ASC oil caps 100mF/375V $20 each and bypassed caps Mundorf Silver/oil .1mF/800V $18 each) and BYOB amp (coupling caps Sonicap GenI 10mF/1200V $20 each and bypassed caps Jensen PIO .47mF/630V $40 each). They are an excellent combination with much better sounding than the stock ones. The sound has great image in high and mid but not lack of plenty of defined deep tight bass. Here is the picture of Altmann gears with RWA/SMART battery charger.



Tan

[anubisgrau]

I've just god some Mundorf Supreme's (plain ones, not SIO) 4.7uF to exchange these 3.3uF Wima's, searching for more organic quality in the BYOB sound.

Any thoughts what would be a good choice to bypass the Supremes?

[tanchiro58]

Any thoughts what would be a good choice to bypass the Supremes?

Anubisgrau,

I bypassed the Sonicraft GenI 10mF with Jensen Paper tube 0.22mF/630V.

Tan

[pardales]

This is a little off topic, but, is it possible to lower the gain of the Attraction DAC?

[daz_bike]

Some say using bypass caps on the output source signal is never a good thing and a single cap always sounds better.

Any opinions on bypassing or not?

[anubisgrau]

This is a little off topic, but, is it possible to lower the gain of the Attraction DAC?

I don't know if this answer is of any use, but when I asked Charles Altmann the same about the BYOB, he told me to solder a quality 25k resistor into the ICs. So I would assume this trick can be used with the DAC too.

Thanks Tan, however I know that so many modders increasingly avoid bypassing caps......

[tanchiro58]

Some say using bypass caps on the output source signal is never a good thing and a single cap always sounds better.

Any opinions on bypassing or not?

That is not totally true. I bought a modded Attraction DAC with output oil caps then I bypassed them with Mundorf Silver/Oil 0.1 mF metallized polypropylene. The combination sounds excellently. It is depending on the matching between coupling and bypassing caps. One thing I should say that you just buy caps and try them on until you get the sound you want in your own system.

I don't know if this answer is of any use, but when I asked Charles Altmann the same about the BYOB, he told me to solder a quality 25k resistor into the ICs. So I would assume this trick can be used with the DAC too.

Anubisgrau,

You could try to use the high quality 25K into IC(?) or maybe another high quality 100K resistor to replace your volume pod but you need to have your either volume control of your source or any preamp that is matched with BYOB amp (i think one of your question before).

Tan

[texendo]

I just recently replaced my Jensen PIOs (2.2uF) with Mundorf SIOs (3.3uF) on the output caps in my Altmann Attraction DAC with no bypasses.  The Jensens themselves were readily apparent upgrades over the WIMAs, and I too immediately noticed more "bass virilty."  The Mundorfs really seem to have opened up the extreme frequencies and lifted another significant veil from the sound.  Highly recommended tweak, but there are some slight difficulties with the stock lengths on the Mundorfs' leads.

[kyrill]

maybe you dont need ANY outputcap on the Altmann Dac, just a superb little piece of gold wire
for that length will be really cheap
Why that solution?
As any very short wire  sounds better than any cap money can buy.
BUT ONLY if you know you can trust the INPUT cap of yr next apparatus ( probably a preamp or power amp.)
You DONT NEED 2 caps in series with an IC in between
actually you SHOULD NOT WANT 2 caps in series.

[texendo]

That sounds like it could be worth a try...

[richidoo]

Reducing gain by increasing feedback in the output opamps as Charles suggests will also change the sound of the DAC slightly, but 2134/4134 sounds pretty good over a wide feedback range. I am not sure where the gain is coming from, the 2134s or 4134. It could be the first pair on the 4134s. I have no idea which resistor would change, but I could find out if you really want to know. For use with the BYOB amp you want a lot of gain and current coming in. I would not change the DACs gain.

Does the gold wire reduce gain because of added resistance? Sounds like a really cool idea!
Thanks
Rich

[anubisgrau]

Anubisgrau,

You could try to use the high quality 25K into IC(?) or maybe another high quality 100K resistor to replace your volume pod but you need to have your either volume control of your source or any preamp that is matched with BYOB amp (i think one of your question before).

I have too much gain in my system, far too much with 115db eff. speakers. I believe 100k would exactly give a more user friendliness than what I have now with a stock pot (saturation at 8 o'clock).

As I'm using it either with Altmann DAC direct or with 0db TVC, what kind of matching between them and a (100k ladder att.) modded BYOB you've had on mind? The main reason why I would change a stock pot with a higher R att is a) sound quality b) gain reduction.... Pls advise

Btw Tan I owe you an apology. I remember you mentioned in earlier posts that your BYOB sounded coarse and harsh. I objected this is not how BYOB usually sounds, but this is exactly how it sounds with top revealing and transparent yet neutral speakers. Now I'm on your trail, to get rid of its harshness and glassy mids without compromises with transparency and bass drive. It is still a bit hard to imagine it can be elevated to the level of a good 2A3 SET, but I fully trust your experience.

[tanchiro58]

anubisgrau,

There is no need to apologize. Actually it was my own experience since i could not stand to hurt my ears. I got to do something and did not care about anything will happen to my byob amp based on my basic knowledge about this matter. I am glad that I got a good result. Therefore, I would like to share this experience to the byob amp's owners who struggle with this problem.

To tell you the truth, I still love very much the sound of my Altmann Attraction DAC and BYOB amp after several changes in modification than my SET 2A3 amp. Besides I also like the sound of the combination of BYOB amp (even though it is an integrated amp) and Promitheus Apollo preamp (pcc189 tube version) and Promitheus DAC.

I am very happy that you finally agree with your own decision. Good luck.

Tan

[pardales]

This is a little off topic, but, is it possible to lower the gain of the Attraction DAC?

I don't know if this answer is of any use, but when I asked Charles Altmann the same about the BYOB, he told me to solder a quality 25k resistor into the ICs. So I would assume this trick can be used with the DAC too.

Yeah, he told me the same thing. Beyond my ability or interest. Do you guys know who could make a battery cable like the one Charles sends along with his gear? I need another one. PM me if you have any suggestions.

[richidoo]

BYOB sounded coarse and harsh. ... to get rid of its harshness and glassy mids without compromises with transparency and bass drive.

Some things you can do to enhance BYOB sound:
Install a real heatsink, lower the operating temperature and elimate the distortion of thermal protection trying to kick in. The stock heatsink is just for show, it doesn't even touch the chip. With no heatsink the chip can make no power without coming into thermal protection, which sounds like you're describing. I made a post a while back with pics about a heatsink from Mouser that works great, about $10. The heatsink must touch the entire chip tab with heat grease. http://www.audiocircle.com/index.php?topic=47130.msg442242#msg442242

Also play it into a 4 ohm speaker, to get more current out of it (10W at clipping.) It is not happy playing into high impedance drivers like some single drivers or exotics. Output power falls to nothing and you can hear the clipping and see it easily on a scope. At 8ohms resistive load, it makes 5W at onset of clipping. I have 14.5 ohm speakers, 95dB sensitive, and it clips readily. Obviously you already have speakers. Maybe try a pad, although I thin kyou will hear it with 115dB sensitivity, wow!

Last thing to try is run the chip on a race car battery that gives 16V nominal, instead of 12. Or make an unregulated 16V/10A DC supply with some nice filter caps like Jensen 4 pole. The chip has good ripple rejection, so you might get by without a regulator. If you need a regulated supply, Paul Hynes can hook you up, but his stuff is ultimate high end, so be prepared to pay. Input power can never exceed 18V while it is turned on, which is why he says disconnect before charging (with normal fast chargers.)  Playing at 16V the BYOBs specs are much better than 12V. More power, less distortion. It uses a car audio chip, which is designed to run on a car battery plus alternator at the same time, which is usually about 14.5V or more.
Rich

[richidoo]

Gordy found these battery terminals:  http://www.wirthco.com/battery_fuse_block_accessories_deluxe_battery_terminal_clamps-c-7_98.html

http://www.wirthco.com/pdf/Battery%20Terminals%20and%20Terminal%20Clamps.pdf
I can't find a stocking dealer with online sales, but these folks may stock it:
http://www.smithae.com/wirthco.html

Not exactly Altmann, but the wingnut should make a more firm connection than the knurled screw. And the rings should dig into the posts better, the Altmann will twist unless you have it pushed far down on the post and tighten hard. Looks like more space for tightening the ring before it bottoms out on itself. Nice find Gordy!

Now we just gotta find the plastic molded plug that connects to the BYOB. I can check mine for a brand mark if you don't have one to check.
Rich

[*Scotty*]

Here is a link to a large number of battery clamps. You can pick your poison, sixteen different clamps.
http://www.partsexpress.com/webpage.cfm?webpage_id=3&CAT_ID=35&ObjectGroup_ID=732
Scotty

[Gordy]

Here is a link to a large number of battery clamps. You can pick your poison, sixteen different clamps.
http://www.partsexpress.com/webpage.cfm?webpage_id=3&CAT_ID=35&ObjectGroup_ID=732
Scotty

Part # 263-610 is virtually the same and available!  As for the pcb end cable connector, mgalusha pointed these Mate-N-Lok connectors out to me... could somebody with the cable verify the body type, if they are indeed the proper type?   http://www.mouser.com/catalog/633/1330.pdf