passive preamp for AKSA (kind of)

jesserparker · « **on:** 11 Mar 2003, 07:47 pm »

hi,
i had wanted to build a completely passive preamp for an aksa55, with input selection and volume, pre-out, and possibly a tape loop. i was wondering if anyone out there has built one, and their impressions of it, and how they laid it out, what parts etc... or if there are any good schematics for a suitable one online. any help would be greatly appreciated, thanks
jesse

Malcolm Fear · « **Reply #1 on:** 11 Mar 2003, 08:01 pm »

I built one about 18 months ago, using DACT stepped attenuator and selector switch.
I was very happy with it. I thought I had reached the end of the line. Then I bought an original TLP line stage. It was much better than a pssive. More dynamic, more detail, better imaging.
I upgraded to the TLP mark 2 (the current one). Again, much better than a passive.
I recently bought the GK-1. It is way better than a passive. The GK-1 will give you more dynamics, better imaging, height etc.
I have compared the GK-1 back to some expensive passives. I find the passives very boring and flat.

bart11073 · « **Reply #2 on:** 11 Mar 2003, 09:17 pm »

I was wondering what the difference is between the TLP and the GK-1 qua sonics?

Just curious...

bart11073 · « **Reply #3 on:** 11 Mar 2003, 09:29 pm »

btw:
On http://www.dact.com/ are schematics for passive preamps.

Malcolm Fear · « **Reply #4 on:** 11 Mar 2003, 10:02 pm »

>>TLP versus GK-1.

The TLP was an improvement on the passive. I was very happy with it.

The GK-1 was the single biggest improvement I have ever made. The dynamics and height of image is what got me. It is also much more open and airy. It also has that "emotional - involving" sound.

frankbr · « **Reply #5 on:** 12 Mar 2003, 04:44 am »

Did you build it into the power amp or outside ? I have heard that a passive pre-amp sounds lifeless if it is set at any distance from the input into the amp so that it needs longer wiring.

I am also interested in putting in a source selector and a balance control directly into the amplifier itself but likewise don't know exactly how to do that.

Would I be right in supposing that the gain on the AKSA is sufficently high that it would not need a pre-amp for most inputs (tuner, DVD, CD, tape) except a turntable ?

Quote from: Malcolm Fear

I built one about 18 months ago, using DACT stepped attenuator and selector switch.
I was very happy with it. I thought I had reached the end of the line. Then I bought an original TLP line stage. It was much better than a pssive. More dynamic, more detail, better imaging.
I upgraded to the TLP mark 2 (the current one). Again, much better than a passive.
I recently bought the GK-1. It is way better than a passive. The GK-1 will give you more dynamics, better imaging, height etc.
I have compared the GK-1 back to some expensive passives. I find the passives very boring and flat.

Malcolm Fear · « **Reply #6 on:** 12 Mar 2003, 04:49 am »

I built the passive in a small box, with lead lengths of about 12 inches from cd to passive and 6 inches from passive to power amp.

jesserparker · « **Reply #7 on:** 12 Mar 2003, 07:48 pm »

does anyone have an experience of a passive they preferred to an active preamp?
also, has anyone built an internal passive, avoiding the wiring that always hurts a passive?
i was going to build mine as an integrated. thanks,
jesse[/i]

JohnR · « **Reply #8 on:** 12 Mar 2003, 08:35 pm »

I'm still using a passive with my AKSA. I kinda think it comes down to cost, you need to spend more to get a better active than a decent passive. My suggestion would be to perhaps build the passive but keep it nice and simple, and later on build a GK-1.

SamL · « **Reply #9 on:** 12 Mar 2003, 09:16 pm »

Hi Jesse,
I am using DACT passive pre with DACT source selector. I build it about 2.5 yrs ago. I kept the wire short. The shortest wire inside is 2.5 inches and the longest is about 6 inches. I wire some RCA with 32ga silver, some with 24ga silver and one cat5 24ga copper - all silver wire are teflon insulated. With surprise, I am able to pick up the sound different in the such short length cable.
My favorate wire is 32g silver. It sound greate from start. 24ga silver is the worse even after 2 days of burn in.
Anyway, to me this show the quality of the dact component.
I'd tried some nz$1000 - $1500 power preamp and although they have more high, more bass, more attack but more noise too. Vocal sound harsh and matalic. Music sounds like they are in a rush and I can't wait to get out the room. The passive is crisp, smooth and clean and all this is important to me. Rock music is not as exciting but I listen mainly to female vocal so it is not a problem.
BTW, I have not listen to AKSA preamp so I am not sure how they compare but base on what I read, GK1 is worth listening.

Sam

jesserparker · « **Reply #10 on:** 12 Mar 2003, 10:47 pm »

hey, thanks guys,
you have any schematics for these? also, do you just have input selectors and gain pots, or have you made any provision for pre-outs or a tape loop too? i'd like to at least have a pre-out so i can attach an outboard headphone amp later. thanks.
jesse

frankbr · « **Reply #11 on:** 12 Mar 2003, 11:30 pm »

I would be interested in any schematics as well if someone wanted to post them online.

Quote from: jesserparker

hey, thanks guys,
you have any schematics for these? also, do you just have input selectors and gain pots, or have you made any provision for pre-outs or a tape loop too? i'd like to at least have a pre-out so i can attach an outboard headphone amp later. thanks.
jesse

SamL · « **Reply #12 on:** 13 Mar 2003, 04:17 am »

Sorry I don't have a schematics. I follow the plan from DACT site. I changed it slightly by connectiong the earth from all the RCA in directly to the earth on the RCA out. A friend asked me to do so to prevent "pop" when switching source and my components are power from the same power point. I don't have tape or preamp out.
Like any point to point soldering, it can be a massy job but if you lable the wire and do it slowly, you will be right.

Sam

tg3 · « **Reply #13 on:** 13 Mar 2003, 04:28 am »

Transformer volume controls (TVC) are the rage in some cirlces. I'm leaning towards the Bent Audio TX-102, which you can build from a kit.

jesserparker · « **Reply #14 on:** 13 Mar 2003, 08:26 am »

ok, so i realize i posted this in the first place, but i may very well have found the solution anyways....
check out this article, it sounds great and is a good read besides.

http://www.stereophile.com/showarchives.cgi?54:0

at any rate, check it out and let me know what you think, or if anybody knows anything about this type of design, thanks....

jesse

jesserparker · « **Reply #15 on:** 13 Mar 2003, 08:31 am »

almost forgot to add, in case you hadn't, make sure to read the following mods to the original version of this preamp he has listed, check those out too.... that's where it gets even more interesting
jesse

mb · « **Reply #16 on:** 13 Mar 2003, 09:58 am »

Quote from: jesserparker

ok, so i realize i posted this in the first place, but i may very well have found the solution anyways....
check out this article, it sounds great and is a good read besides.

http://www.stereophile.com/showarchives.cgi?54:0
jesse

At this very moment I'm listening to a resistor-based attenuator with active buffer, a la Aunt Corey. It sounds excellent. I've made several versions, using premium attenuators, really cheap attenuators and different types of battery supply (2*12V sealed lead acid, 2*9V NiMh, 2*9V NiCd). In all cases the results are way above expectation, and definitely better than passive alone. The buffer adds drive and bass, and does NOT add transistory glare or harshness. This was not the case when I tried opamps after a passive, even pretty exotic opamps.

TLP or GK-1 vs a good passive + buffer (battery powered)?? Well I've heard all three + a highly tweaked Foreplay + a Krell KRC-2. I'm sticking to the attenuator + buffer.

Johnny · « **Reply #17 on:** 13 Mar 2003, 06:27 pm »

Quote from: jesserparker

almost forgot to add, in case you hadn't, make sure to read the following mods to the original version of this preamp he has listed, check those out too.... that's where it gets even more interesting
jesse

Hi Jesse, This does sound interesting! Where are the mods you refer to?
Was thre a link?
Thanks,
Jy

jesserparker · « **Reply #18 on:** 13 Mar 2003, 08:40 pm »

the mods are listed right after the first whole article. theres the original article, then some letters and stuff, and then a whole other article about mods he did to it.
also, if you just go over to the far right hand side of the screen you can pick what pae you want to go to and the "mo' better mods" are listed there too... makes what sounds like a great idea look even more tasty.

SamL · « **Reply #19 on:** 14 Mar 2003, 12:45 am »

Thanks Jesse for sharing your finding.

I did a search on AA and it got some interesting cover on this preamp.
Anyway, for those interested, found this power supply site that maybe useful.
http://groups.msn.com/DIYElectronics/advancedpowersupply.msnw

Have fun,
Sam