Modded Altmann BYOB amp

tanchiro58 · « **on:** 5 Nov 2007, 11:11 pm »

Hi,

I just finished modifying my Altmann BYOB amp by replacing the output coupling caps and the volume control.

Any suggestions to improve the sound are welcome even though its sound is matched pretty well with my Altmann Attraction DAC and the rest of my system. Thanks in advance.

Regards,
Tan

F-100 · « **Reply #1 on:** 6 Nov 2007, 01:52 am »

Very nice, Tan.

Can I borrow it for a week?? aa

rodge827 · « **Reply #2 on:** 10 Nov 2007, 02:54 am »

Hey Tan,

I also modded my Attraction Dac similarly to the one you purchased on Agon. I've burned in about a 1000 hours on it and WOW!!! detail and Bass in spades.

. I'm very anxious to hear how your BYOB Amp mod went. I don't own the amp yet, but if your amp mod does what the Dac mod did, then one just might make it to my shack.

Please keep us informed of how things sound after burn in.

Thanks,

Rodge

tanchiro58 · « **Reply #3 on:** 10 Nov 2007, 05:07 am »

Quote from: rodge827 on 10 Nov 2007, 02:54 am

Hey Tan,

I also modded my Attraction Dac similarly to the one you purchased on Agon. I've burned in about a 1000 hours on it and WOW!!! detail and Bass in spades. . I'm very anxious to hear how your BYOB Amp mod went. I don't own the amp yet, but if your amp mod does what the Dac mod did, then one just might make it to my shack.
Please keep us informed of how things sound after burn in.

Thanks,

Rodge

Hello Rodge,

I noticed that it has an amazing sound I have never heard before two days after modifying. The recent combination makes me think not to spend any dimes for the best system I would like to. I just added an Elna Cerafine 10,000mF/63V to connect parallel with battery PS of the BYOB amp (not shown in the picture) based on mgalusha' s band of electrolytic caps to his borrowed Attraction DAC. The sound has more defined deep bass as well as more separated details in mid and high. I will try to do the same to my already modded Attraction DAC tomorrow. Will let you know.

Regards,
Tan

anubisgrau · « **Reply #4 on:** 10 Nov 2007, 09:49 am »

guys, what were your objections to the sound of the stock BYOB/DAC?

also, are PCBs glued to the wood or just screwed - difficult to perform mods?

cheers

texendo · « **Reply #5 on:** 10 Nov 2007, 01:17 pm »

The PCB on my DAC is simply screwed to the board, no glue. I removed the retina searing blue LED (as I do from all my equipment) that burns brightly while the unit is playing music. There were small improvements in high frequency smoothness, but mostly the improvements were asthetic. I experimented with removing some of the electrolyitc caps as some have done (claiming they hate the sound of them), but to my ears the caps sounded far better in place. My guess is that the other modder had not given the caps sufficient time to burn in before removing them (hundreds of hours with such low current applications). I would love to replace those WIMA output caps with some VH caps as I believe that is the weakest link of this otherwise outstanding DAC.

rodge827 · « **Reply #6 on:** 10 Nov 2007, 03:16 pm »

Gents,

I bought my Dac (basic with Jisco) used from a guy who does his own mods and builds his own gear. Very high end stuff at that. Point is that he knows what he is doing. The Dac in the stock form sounded superb to me. While discussing the Dac he pointed out that a few changes that would make it sound better than it does, all the while stating that Altmann put together a great piece of gear with some budget parts. So we did the Mods he suggested, Blackgates for the electrolitics, and a matched set of Audio Consulting silver and oil 47uf couping caps. He said give it about a 1000 hours and there will be a substantial difference. He was RIGHT !!!! Loads of deep clean bass with crystaline highs with a mid that just sounds RIGHT!!! With no digital ETCH !!!!.

So thats my story and I'm stickin' to it.

FWIW, I know very little about parts and what works and what goes where so I won't be able to answer any technical EE type questions. I just put some faith in a fellow audio dude and I'm glad I did.

Tan, Thanks for the reply. After you get some time on your amp, I'm curious to see how it stacks up to other designs, mainly 300b and A23 tubes.

Rodge

tanchiro58 · « **Reply #7 on:** 10 Nov 2007, 04:30 pm »

Quote

Tan, Thanks for the reply. After you get some time on your amp, I'm curious to see how it stacks up to other designs, mainly 300b and A23 tubes.

Rodge,

I did compare to my other two 2A3 SET amps (custombuilt 2A3 parallel and modded Sun Audio 2A3 amps). The modded BYOB amp sounds far more better everyday than my other two amps in my main system. To be honest with you my main system sounds even much better than my my friend 20K system IMO and to my ears. I could not resist to listen to my main system every day (before just only weekends).

Tan

anubisgrau · « **Reply #8 on:** 10 Nov 2007, 10:26 pm »

why don't you put a TVC volume control?

kyrill · « **Reply #9 on:** 10 Nov 2007, 10:48 pm »

hi Tan

Did i miss yr post of the mods you did with the Altmann dac?

tanchiro58 · « **Reply #10 on:** 10 Nov 2007, 11:29 pm »

Quote

why don't you put a TVC volume control?

Anubisgrau,

I have tried two different Promitheus Audio TVC preamps (if you mean it) and do not like the sound at all. I rather modified the BOYB amp like you see the picture of it. This matched pretty well with my modded Attraction DAC. Here is a picture:

Tan

texendo · « **Reply #11 on:** 18 Nov 2007, 08:38 pm »

Quote from: rodge827 on 10 Nov 2007, 03:16 pm

Gents,

I bought my Dac (basic with Jisco) used from a guy who does his own mods and builds his own gear. Very high end stuff at that. Point is that he knows what he is doing. The Dac in the stock form sounded superb to me. While discussing the Dac he pointed out that a few changes that would make it sound better than it does, all the while stating that Altmann put together a great piece of gear with some budget parts. So we did the Mods he suggested, Blackgates for the electrolitics, and a matched set of Audio Consulting silver and oil 47uf couping caps. He said give it about a 1000 hours and there will be a substantial difference. He was RIGHT !!!! Loads of deep clean bass with crystaline highs with a mid that just sounds RIGHT!!! With no digital ETCH !!!!.

So thats my story and I'm stickin' to it.

FWIW, I know very little about parts and what works and what goes where so I won't be able to answer any technical EE type questions. I just put some faith in a fellow audio dude and I'm glad I did.

Tan, Thanks for the reply. After you get some time on your amp, I'm curious to see how it stacks up to other designs, mainly 300b and A23 tubes.

Rodge

Who was it that did your mods for you? Any chance you could share the contact info?
Thanks!

tanchiro58 · « **Reply #12 on:** 18 Nov 2007, 09:49 pm »

Texendo,

It is all about DIY. As I know the previous Attraction DAC's owner is medical equipment's engineer and he did the modifying. Basically he just removed the wima coupling caps, filter caps and relay in the stock DAC. Then he got the ASC oil caps 100mF/375V to put in the place of the wima. He also added to the spruce board with a plywood (painted black in picture) and three BRD cones to hold the huge ASC caps and the original DAC.

My parts I modded are two Mundorf Silver/Oil 0.1mF/800V to bypass the ASC oil caps and a Jensen electrolytic 10,000mF/25V to bypass the 12VDC PS from battery using as a booster and filter. And I modded my BYOB amp from the stock one. Any questions I will be happy to answer.

Tan

texendo · « **Reply #13 on:** 19 Nov 2007, 01:25 am »

Agreed about DIY, I'm an avid fan : ) I wanted the contact info because I'm unsure as to what voltages of blackgates are necessary. I would think the 6.3V would be sufficient without having to go the the physically more cumbersome and expensive 16V and 50V versions (for the 47uF and 200uF caps respectively), but then again, I don't know.

I've already replaced the WIMAs with some Jensen PIOs 2.2uF that I had lying around, and the improvements are so nice that I want to go all out. Vcap teflons are out of my range, but I'm thinking about some Mundorf silver in oils at 3.3uF. Would love to just go ahead and order some blackgates while I'm at it. Any input would be appreciated.

anubisgrau · « **Reply #14 on:** 16 Dec 2007, 12:31 am »

Quote from: tanchiro58 on 10 Nov 2007, 11:29 pm

Quote
why don't you put a TVC volume control?

Anubisgrau,

I have tried two different Promitheus Audio TVC preamps (if you mean it) and do not like the sound at all. I rather modified the BOYB amp like you see the picture of it.

Well, my idea is to use a pair of decent trafos - like S&B which i have in my bent TVC - and i good switch, like seiden - to see what is going to happen. For me it's pretty hard to accept before testing that a resistor based switch can beat a pair of good trafos and a decent switch when it comes to the volume control.

I also didn't go well along with Prometheus TVC, I ultimately found its sound quality insufficient for a serious use.

Speaking of the mods, I'd love to see more than a single input on the amp. Any thoughts how this should be done without harming the sound quality?

tanchiro58 · « **Reply #15 on:** 16 Dec 2007, 01:21 am »

Quote

Speaking of the mods, I'd love to see more than a single input on the amp. Any thoughts how this should be done without harming the sound quality?

Since I replaced the stock volume control with a Goldpoint 24 step attenuators to the BYOB amp I do not hear any degradation of the sound. It even sweetens the sound without hurting my ears like before.

anubisgrau · « **Reply #16 on:** 16 Dec 2007, 01:43 am »

Quote from: tanchiro58 on 16 Dec 2007, 01:21 am

Quote
Speaking of the mods, I'd love to see more than a single input on the amp. Any thoughts how this should be done without harming the sound quality?

Since I replaced the stock volume control with a Goldpoint 24 step attenuators to the BYOB amp I do not hear any degradation of the sound. It even sweetens the sound without hurting my ears like before.

Hey, but the stock BYOB amp doesn't hurt ears. I've never heard of such an experience with it. OK it's not sweet but in my system it never sounded harsh or aggressive, on contrary, very neutral, clean and transparent. Are you sure you are not dealing with something else in your system while modding the BYOB?

tanchiro58 · « **Reply #17 on:** 16 Dec 2007, 04:35 am »

Quote

Are you sure you are not dealing with something else in your system while modding the BYOB?

Anubisgrau,

Before I did the modification to the BYOB amp I had tried step by step every chain in my system but no success. Maybe it is depending on every synergistic system. My system is very sensitive (got high efficient speakers) so I modded the BYOB amp to match every chain to avoid the harshness and loudness of the stock amp. I do not like to use too many transformers in my system since they sound constrained.

anubisgrau · « **Reply #18 on:** 6 Jan 2008, 12:34 am »

OK, my S&B 102 Mk3 TVC trannies are on the way.

I am seeking for a recommendation for a really good volume switch to be used with the above trannies.

Also, would anyone who perform mods to the BYOB care to make a list of the mods done just to make life of us who are not that handy with soldering a bit easier. The full list of the parts exchanged with the values would be much appreciated!

Gordy · « **Reply #19 on:** 6 Jan 2008, 03:49 am »

Quote from: anubisgrau on 6 Jan 2008, 12:34 am

I am seeking for a recommendation for a really good volume switch to be used with the above trannies.

Bent Audio sells the 23 position Shallco switch for $100, with remote it's $300. Click on the DIY parts button... http://www.bentaudio.com/index2.html

Another nice switch is the 23 position Seiden which goes for $60 but, shipping is pricy from DIYSupply... http://www.diyhifisupply.com/diyhs_dact_switches.htm