[dewardh]

So does that mean that single ended inputs are equally as good as balanced, or that balanced inputs are no better than single ended?

Yes.  When driven by a “single ended” output a “balanced input” has no inherent advantage.  In the case of the CDA series amps, however, the implementation of the single ended input has some issues (corrected in the SDS series) that may have negative impact in some systems.  If those issues do not apply to your system, or are correctable by you, then the addition of an input buffer, balanced or otherwise, will not provide any benefit.  It all depends . . .

The CDA input impedance is quite low . . . typically 4000-5000 Ohms (depending on the built-in gain setting).  Not all sources can drive that properly . . . so-called “passive pre-amps”, for example, cannot, producing interactions that can induce distortion and compromise frequency response.  On the other hand if your source can handle the load it is not an issue.

The CDA amplifiers invert (at the output) the signal.  This is generally not audible, and is easily corrected simply by reversing speaker leads, but in a bi-amped installation when used with other (non-inverting) amps it can, if not corrected for,  cause significant dropouts in the frequency response (and may impact “imaging”, which almost always reflect  a speaker/room problem, not an amplifier problem).

The CDA amps use a rather questionable input coupling capacitor.  It is easily bypassed (and replaced), but some familiarity with circuit tracing and working with the (very small) smd used is necessary . . . it may not be a task for beginners.

The “stock” gain setting, especially of the higher power amps, is generally too high, resulting in amplification of noise from source devices.  This also is easily fixed, but again requires some familiarity with working with smd components (one can also specify the gain desired when ordering the amp boards, or add a gain control).

The net result is that the CDA amps are great bargains for someone with a little familiarity with electronics who can properly match them to existing gear.  What the SDS series brings to the table (for  another $100) is an input buffer that resolves the above issues without the necessity of any board-level modifications by the end user.  Input impedance is raised, polarity inversion is switchable, and a volume control is added.  In systems where those things matter and have not been otherwise resolved by the builder the result may be “better” sound overall, and the greater ease of matching to a variety of “source” components may offer a worthwhile convenience.

[roymail]

The CDA input impedance is quite low . . . typically 4000-5000 Ohms (depending on the built-in gain setting).  Not all sources can drive that properly . . . so-called “passive pre-amps”, for example, cannot, producing interactions that can induce distortion and compromise frequency response.  On the other hand if your source can handle the load it is not an issue.

Tom has assured me that the input impedance of their amps is 45k.  I have the emails if anyone needs to see them.  Just trying to help and limit any confusion.

[dewardh]

Tom has assured me that the input impedance of their amps is 45k.  I have the emails if anyone needs to see them.  Just trying to help and limit any confusion.

That is true of the new amps.  It is not true of the "original" CDA amps . . .

[roymail]

I'm sending a PM your way.

Previously, Blair Lamphear (Niteshade Audio), stated that the CDA-254 worked great with a passive attenuator and raved about the amp's performance.  I don't believe that Blair would say that and market his own version of the amp using the CDA-254 amp board if it had so many issues.

[steve k]

So are these amps still going to be featured in Affordable Audio?

The latest from Tom is it should be in the June issue.
steve

[wushuliu]

I'm sending a PM your way.

Previously, Blair Lamphear (Niteshade Audio), stated that the CDA-254 worked great with a passive attenuator and raved about the amp's performance.  I don't believe that Blair would say that and market his own version of the amp using the CDA-254 amp board if it had so many issues.

Deward is just emphasizing that *depending on your setup* you can potentially squeeze out more performance from the amp. He's obviously a big fan of these amps and is just presenting options, especially to those of us who like to wake up to the smell of solder in the mornin'. There's no question of them having great performance out of the box...

[wushuliu]

The latest from Tom is it should be in the June issue.
steve

Awesome. Congrats to him.

[Nick77]

       He's obviously a big fan of these amps and is just presenting options, especially to those of us who like to wake up to the smell of solder in the mornin'                                                     

Love it!  Diy Rules!

[wushuliu]

Love it!  Diy Rules!

Have to be careful though. I just fried my classd amp this weekend Not quite sure what happened, but we had just finished moving to a new place and I started getting audio stuff set up. Probably something got jostled (actually I'm sure it's related to my first modding attempts back when I got the board in November which was sloppy *and* unncessary). I was too eager to get things going, was very tired, and I knew i should have given everything a once over and made sure the enclosure was ok, etc.

My new board should be arriving today... so be careful!

[Nick77]

Have to be careful though. I just fried my classd amp this weekend Not quite sure what happened, but we had just finished moving to a new place and I started getting audio stuff set up. Probably something got jostled (actually I'm sure it's related to my first modding attempts back when I got the board in November which was sloppy *and* unncessary). I was too eager to get things going, was very tired, and I knew i should have given everything a once over and made sure the enclosure was ok, etc.

My new board should be arriving today... so be careful!

Ouch!       Sorry to hear that, is the power supply with the panasonic's ok?

[wushuliu]

Should be. The sparks and smoke came from the amp . I'll find out tonight...

[Nick77]

Should be. The sparks and smoke came from the amp . I'll find out tonight...

Did you get the same board?

[wushuliu]

Did you get the same board?

Yes. I was tempted to get the Super, but my will is strong, like my kung fu!

[Nick77]

Yes. I was tempted to get the Super, but my will is strong, like my kung fu!

Your will is strong Ninja-son, now fire that badboy up and report back!

[wushuliu]

Here's a question for enclosure folk: My amp is housed in a wood enclosure. It's alright, but I'd like to step up to one of the ParMetal enclosures on ebay.

I have zero experience w/ metal enclosures. I live in an apartment and no access to major tools - just a basic drill. How do I go about making 3/8" and smaller holes for the rca/posts, etc? (rear panels are .06" thick aluminum). I've done searches all over, but surprisingly little info on these kinds of holes.

if this question should go somewhere else, lmk...

[jtwrace]

Here's a question for enclosure folk: My amp is housed in a wood enclosure. It's alright, but I'd like to step up to one of the ParMetal enclosures on ebay.

I have zero experience w/ metal enclosures. I live in an apartment and no access to major tools - just a basic drill. How do I go about making 3/8" and smaller holes for the rca/posts, etc? (rear panels are .06" thick aluminum). I've done searches all over, but surprisingly little info on these kinds of holes.

if this question should go somewhere else, lmk...

Have you seen my gallery with my case?  Take a look...it's right up your alley.

[wushuliu]

Have you seen my gallery with my case?  Take a look...it's right up your alley.

i know, but I am *way* broke. like post-move, post-flew to somebody's wedding far away, now post replaced dead amp broke...

[jtwrace]

i know, but I am *way* broke. like post-move, post-flew to somebody's wedding far away, now post replaced dead amp broke...

 

If you can rig it up so it's safe, I would do that.  Then when you save up the money, BAM you're good to go.  This case is perfect for you as you don't need to use any power tools...

[Mariusz]

Wushu
sorry to hear about your misfortune.
I'm sure you will be back on your feet before you know it.

As to your Q -
I am not the most knowledgable person but when it comes to drilling holes in metal, this is the easiest way that works for me:
step drill bit
(there are few versions out there- get the one that Ull need the most)

Best
Mariusz


P.S

there are some nicely made cases on eBay.(made here in US)
look here


 

[wushuliu]

Thanks Mariusz. That's what happens when you rush things. but, hey, they're so cheap it's not that huge a deal. So I figure while I'm at it, might as well get it a proper enclosure. Make 'er respectable.

I've heard mention of the step drill bit. I'm guessing all I need is a center punch, step drill bit, maybe some lubricant. Yes, I've been eyeing those enclosures straight out of NJ for some time.