Changed amps - center image moved


I recently changed amplifiers from TRL Samson (monos) to Maker Audio Ref 2A stereo amp.  Both amps are superb but using the same associated equipment (DAC preamp, sources, speakers) my center image changed significantly.  I did go from single ended to balanced interconnects.  The Maker has a much wider image (well beyond outside of speaker but the center image is diffuse (not specific).  Also, with the Maker amp, more sound comes directly from the speaker (very little w the Samsons).  The TRL Samsons had a specific center image but more narrow width (very little outside of speaker).   In a perfect world, I would have the specific center image plus the ultra wide space.  Anyone experienced a similar situation and how (were) you able to optimize.  Don't get me wrong though, the Maker is fabulous in every aspect....killer detail without edginess, dynamics that are breathtaking.

Just trying to figure ways to re-attain the center image specificity.  Suggestions?


jeffga

Showing 6 responses by almarg

A reversal of polarity between XLR pins 2 and 3 at some point in the signal path would result in diffuse imaging if and only if it occurred in one channel, not both. Presumably a component design in which pin 3 is the non-inverted signal and pin 2 the inverted signal (which is the opposite of the usual convention in the USA and various other countries) would do that in both channels.

Also, given the reference in the OP to excellent sonics (which would certainly be compromised big-time if a polarity reversal was present in one channel), and the level of sophistication that a user of a Maker Audio product can be presumed to have, I would expect that a polarity reversal in one channel is unlikely to be the cause.

Jeffga, what preamp and what speakers are you using? And is there a subwoofer in the system?

Regards,
-- Al
I have an adapter shipping to me so I can try going back to the previous RCA cables.
I don’t know whether or not this may be applicable to your Maker Audio amplifier, but I’ll mention that there are some amps having only XLR input connectors which will not work properly when provided with single-ended signals via adapters. Certain Audio Research models for example, which have balanced internal signal paths and provide only XLR inputs, are designed such that if they are provided with single-ended inputs half of their balanced signal path will not receive a signal. Resulting in **greatly** reduced power capability as well as some sonic degradation.

You might want to ask Mr. Maker or one of his associates if that concern applies in this case.

A single-ended signal can be converted to a true balanced pair of signals with a device such as a Jensen Transformer (~ $300) or an SMc Audio Flex-Connect ($1895).

Good luck. Regards,
-- Al


P.S: I took a look at the descriptions and the manual for your Theta DAC/Preamp. The one point I’d highlight after looking at them is that in addition to changing the amp and the cables, by changing from RCA to XLR cables between the Theta and the amp you are now utilizing within the Theta (for each channel) two DAC chips, two volume control mechanisms, and two analog signal paths rather than just one of each of those things that were used previously.

In other words, while the signal applied to the RCA output connector for each channel is produced by the same DAC chip and subsequent analog signal path that provides the signal to one of the two signal pins on the XLR connector (probably pin 2), the other signal pin on the XLR connector (probably pin 3) is provided with a signal produced by a completely different (although supposedly identical) DAC chip and subsequent analog signal path. And that different DAC chip and different analog signal path within the Theta were not in use when you were connecting via RCAs.

You can see that in the block diagram on page 11 of the manual, as well as in the description at the Theta website:

http://www.thetadigital.com/downloads/Generation%20VIII%20Series%203.pdf

http://www.thetadigital.com/generation_viii_series_3_dac_preamplifier_info.shtml

So in addition to the possible causes of the issue that have been referred to previously, the Theta itself cannot be ruled out as a suspect at this point. And if changing the XLR cables to RCA cables + adapters resolves the problem, it would NOT necessarily mean that the XLR cables are to blame. In fact if that turns out to be the case I would expect it to be much more likely that the Theta is the root cause of the problem, rather than the cables, assuming there isn’t an outright miswire in one of the cables (which seems very unlikely given the good sonics you have reported).

Good luck. Regards,
-- Al
Wow Al....many thanks for your interest and help!! One interesting tidbit...when I had the Samsons, I used a Cardas XLR to RCA adapter at the DAC side (so to get more output via the AES outputs on the DAC & not need a preamp), thus could use RCA IC’s. The imaging was superb.
You’re welcome, Jeff. But I’m wondering about a couple of things in regard to this statement, if I am correct in interpreting that you were using XLR-to-RCA adapters on the analog outputs of the Theta DAC/Preamp:

1)Using XLR-to-RCA adapters on the XLR analog outputs of the Theta would not have given you any increase in output, compared to using the RCA outputs. As I mentioned earlier the RCA output connector is wired directly to one of the signal pins on the XLR connector, and it is that signal which would have been provided to the Samson via the adapter. The other signal on the XLR connector would not have been used. The reason the XLR output is specified as having twice the voltage of the RCA output is that the spec for the XLR output reflects the use of both signals.

2)More importantly, most XLR-to-RCA adapters short the unused signal (usually pin 3) to ground (pin 1). My understanding is that Cardas adapters can be special ordered to leave pin 3 unconnected. While shorting pin 3 to pin 1 is proper practice for adapters that are used on inputs, with most designs it is definitely something that should be avoided on outputs. Do you know if the Cardas adapter you used shorts pin 3 to pin 1? If you are uncertain that can be easily determined with a multimeter, if you have one.

If that adapter shorts pin 3 to ground (pin 1), given the extremely low output impedance of the Theta (25 ohms balanced, corresponding to about 12 ohms for each of the two signals in the balanced signal pair), a concern would be that over time the short might have adversely affected the health and the performance of the Theta’s analog output circuit which drives pin 3. And if so, that could conceivably account for the imaging issue, since the pin 3 output is now being used (while not having been used when you were connecting to the Samsons).

In any event, good luck as you proceed. Regards,
-- Al


Guys it is possible one speaker has been hook up with the leads reversed. This will in fact cause such a sonic character.
Bill, yes it will, but as I and Seikosha indicated it will also cause big-time sonic degradation, which the OP has indicated multiple times is not occurring. Although as you indicated it’s easy enough to check, and it is certainly something that should be checked.
If not the cause, then yes the amp sounds different with the speakers.
Not necessarily. The Theta DAC/Preamp is also suspect, as I explained in my previous posts. He is now using a signal path of the Theta that was not used with the previous amp. And furthermore he is now using an output circuit of that previously unused signal path that may have been shorted to ground over a prolonged period of time, and whose condition is therefore highly questionable.

Best regards,
-- Al

Outstanding!

So it sounds like there were two problems that were simultaneously present. One of them being reversed polarity on one of the speakers, and the other being suggestive of a defect in one of the two signal paths to one or both of the balanced outputs of the Theta, as I had speculated. That signal path not having been used when you were connecting to the previous amp, and the problem perhaps having been caused or contributed to by the XLR-to-RCA adapters you were using at the Theta’s XLR outputs when you were connecting to the previous amp.

In any event, congratulations on the new amp and enjoy! Regards,
-- Al