[poseidonsvoice]

Anand your build looks amazing. You certainly took some extra measures in regards to power, care to comment on your sonics compared to the stock unit you demo'ed?

A review will come soon enough, but comparing to the stock version will be difficult as I don't trust my memory that much. In any case, I will compare it with another solid state amp I built, the Poseidon's Voice Anjali (pics available in my gallery). I try to compare the solid state amps to each other instead of my tube amps I have just cause they are quite different sounding and I may prefer one or the other depending on mood, appetite, type of music, etc...

If anybody has questions on the build itself, let me know.

Anand.

[toxteth ogrady]

I can confirm that changing the pots outs for some quality resistors on the sds amps has a very positive effect. I changed mine out for the naked Vishay's yesterday. Let's just say I can't wait to get the remaining resistors I have into my DC B1 board. Very satisfied.

[pelliott321]

Just mailed my CDC 254 for tom to look at and maybe change the gain

[Doc77]

This is a great thread guys, I really appreciate all the info on how to mod them ... and not just by throwing darts and hoping for good results.  I'm convinced, it's time to build one!

[J Payton]

I've got a question for bridged mode.

After changing all the jumpers and then connecting the outputs to (left + and Right +) and using the left input.

How do you connect speaker wires to the binding post.


Speaker Wire (-) to amp (left +) or (right +)
Speaker Wire (+) to amp (left +) or (right +)

Since both outputs are + I wasn't sure how to hookup the speaker wire so they are in phase properly for the speaker.

Hope this makes sense.

Joel

[jtsnead]

In bridged mode (SDS-254) you use the left channel positve to the positve speaker output, and the right channel positve to the negative speaker output.

This is what Tom told me and it does sound like it is phase

JT

[J Payton]

JT,

Thanks for the advice.

Joel

[waltsok]

Can anybody help my with the wiring for a power supply using a dual bridge rectifier like the one used in the following link. http://www.tnt-audio.com/clinica/ssps2_e.html

 I now have all the parts but I can't understand the bridge rectifier's wiring. In the diagram it seems that the upper bridge neg out is connected to the lower bridge positive out then both to ground. Otherwise how then can the neg be achieved in the diagram. Can this be correct? Nightshade used a dual rectifier power supply in a March 18th post, could you Nightshade, or anyone else help me out? Thanks Walt

 

[J Payton]

I have a question about the resistor mod.

If your running in bridged mode do you only need one resistor on the left input or do you still need resistors on both the left and right input. I was thinking of buying the naked vishays and was wondering if I could save a few bucks.

Joel

[guest1632]

I have a question about the resistor mod.

If your running in bridged mode do you only need one resistor on the left input or do you still need resistors on both the left and right input. I was thinking of buying the naked vishays and was wondering if I could save a few bucks.

Joel

Hi Joel,

Well, here's how you can know the answer. Assuming you haven't removed the two pots, do the bridge mode. Then while all is hooked up accordingly, then turn the knob on the right pot, and see if there is any affect. If there's no affect, then unplug that pot, and see if all is well. If again, no affect, you have your answer.

Now, if in turning the right pot, the volume drops, then you again have your answer. Let us all know what you find out.

Ray Bronk

[jtsnead]

I am running a bridged SDS-254 and according to Tom you only need the left hand pot attatched, which is the way I have it. So you would only need one resistor per board, mine are on order.

[walkern]

Where are folks sourcing the naked Vishay resistors?  And has anyone compared them with the top end Caddocks?  Would like to try these, but Michael Percy is the only source I've found, and he has a minimum order of $25.

[jtsnead]

mine are coming from Parts Connexion, they are having a 20% off sale right now, 1K naked - $15.95 each. but they charge $15 shipping cost me $41.00 shipped

so if you can get them less than that go for it

[J Payton]

JT Where did you get the power supply.

Is that from Connexelectric ?

How do you like it?

Joel

[toxteth ogrady]

You can get the naked vishay's directly from Texas Components. They were around $9 each plus shipping I think and about a two week lead time.

[jtsnead]

JT Where did you get the power supply.

Is that from Connexelectric ?

How do you like it?

Joel

yes it is from Connex, it probably is a 20% improvement to the stock one, more open soundstage and deeper base, was not noticable at first but after about a week it opened up. Worth the investment for sure.

[guest1632]

yes it is from Connex, it probably is a 20% improvement to the stock one, more open soundstage and deeper base, was not noticable at first but after about a week it opened up. Worth the investment for sure.

Hi JT,

So did you get the dual diode situation set up? What other changes did you make?

Ray

[jtsnead]

Hi JT,

So did you get the dual diode situation set up? What other changes did you make?

Ray

Hi Ray,
what do you mean by dual diode? I am getting ready to install vishay resistors
in place of the volume pots. Also am going to install a felix common-mode choke.
As you can see above I added another amp board so I am running bridged SDS-254's which made a big difference on the quanity and quality of the bass control.
If I new more about power supply construction I would look at improving that like bigger transformer, caps etc. This would have to be on the affordable side though. I looked at Paul Hynes stuff but that is expensive.

JT

[Barry_NJ]

Well I've been auditioning Pumpkinman's CDA-254 build for a bit now, and he's built a nice amp. The wiring is nicely laid out and cleanly routed. The amp sounds pretty good, but I don't feel it's as good as my Audio Alchemy OM150 with a PSU150 and a PSU150M. FWIW the PSU units are nothing more than a transformer and diode, so the extra PSU doesn't add any capacitance to the amplifier. The CDA-254 does have an immediacy that I think the AA amp lacks, but the CDA is also pretty severely lacking in bloom and body. Listening to Johnny Cash, 'American IV - The Man Comes Around' via the two amplifiers really illuminated the differences. With the CDA the strings of the guitar were clearly audible, but the wooden body was pretty much absent, and Johnny's voice took on a slightly nasal characteristic. With the AA the strings were less evident, but the warmth and resonance of the guitar body was clearly there. Another thing that was interesting was the sound-stage presentation. While the CDA may have presented a slightly wider sound-stage, the AA was far deeper both in-front of and behind the plane of the speakers. This was pretty evident on most all recordings, but a favorite demo for this is Peter Gabriel's 'Growing Up' from his album 'Up'.

I'm still interested in the Class-D Audio amplifiers, but only if the SDS boards are closer to my Audio Alchemy, bringing back some of the warmth, resonance, and depth that I feel the CDA board is lacking in my system. Anyone care to comment?

Pumpkinman's amp (from his gallery)...

[nodiak]

Barry, just to be sure - while you were auditioning the amps, everything else in your system remained constant?

I have a CDA-254 and have only had a NAD 1700 preamp so far. Next week should receive a simple tube pre to try, then hopefully later this month a B1. Expect either of these to have more air and space. Also in next few weeks a different solid state amp to try (Ampslab LM60).
I don't love or hate the CDA, thou it's obviously "good" in my system, especially in the bass. I enjoy the power (90db speakers) especially after a run of low power tube amps (with high eff speakers). But for me so far without a better pre can't make any legit comments on it.

Also just rearranged my room to have 5' behind speakers and a 6 foot opening to an adjoining room between them. This above anything else brought wide and deep soundstage and much diminished reflection problems (as always the room rules).

Don