DX-1 XPL-200 Frequency Card Discrepancies

[Ian Mackenzie]

I played a very familiar recording and could not detect what I felt to be any brightness.

It is important to note that bi amping at this frequency has the effect of removing the bloom, grit and other rubbish from the mid cone driver that can otherwise mask the upper frequencies unless great care has been taken with the full passive crossover network.

For this reason an inexperienced user may interpret the subjective result as bright. The apparent bright presentation in Mark's system could be due to a number of environmental factors.

Careful adjustment of the level controls can be used to fine tune the overall balance.

Ian

[Ian Mackenzie]

A modification with potential for improvement of the DX1 is to completely bypass C25, 26, 27, 28, 21, 22, 23 and 24.

These are input/output coupling capacitors (highpass output buffer only) and serve to stop dc entering or leaving the DX1. I was unable to measure any offset that might be consider an issue.

The result is improved transient performance and transparency.

The DX1 is really hitting its stride now.

I have not charge - coupled the crossover boards at this point. Will do do soon.

Ian

[pasadena]

Ian,

With both DX-1's shipped over to Ian, I pulled aprt the NAD 208THX (finally) to check out a suspect connection on my left channel. I am currently using the NAD to bi-wre the XPL's.

Indeed it was as the solder had come apart from the pin due to what looks like plugging and unplugging of the RCA socket over time, which cracked the solder a from the pin. The pin was sliding up and down through the solder.

So, I reheated/resoldered all the joints for all pins for each RCA plug so now they’re workin’ like a gem.

I've noticed an immediate difference as getting more detail through the bottom/top end than I was before and now the over sound is more even to both sides. This may have contributed to why the left channel wasn’t as audible/detailed as the right channel.

I still haven’t plugged the Dr. Thomas power amp on its own to the XPL’s….I know, lazy me but I will get there.

I don’t think that the XPL’s firing with just the NAD is harsh or bright at all but I will keep testing. J

Cheers
Pasadena

[pasadena]

Hi Guys,

Reviving an old thread.

I have a couple of questions I wanted to ask about both DX-1's I have. Long story short, I've moved into our new nouse not long ago and finally I have a dedicated room for my home theatre. I've pulled my XPL-200A's and DX-1's out of storage and started putting everything together.

When I packed everything away into storage, I didn't take not as to which DX-1 was sent to me by Greg Timbers. I have attached a set of pictures of one DX-1 and will post again with pics of the second DX-1. Let me know what you guys think. One set of the DX-1 cards have been modified and I wanted your take on it.

Before hooking my DX-1, I've been using a Marantz AV8801 Pre-Processor running a pair of Electrocompaniet AW400 monoblocks. Am extremely pleased with the sound and still love to this day how good my XPL's are

However, always a but somewhere. After hooking my DX-1, I connected the AW400's to the high pass section through the DX-1 and my DIY Passlabs XA100 Monoblocks feeding the low pass section. Both the AW400 and XA100's have XLR connectors only. A bit of a pain as my AV8801 have both balanced and unbalanced but seeing the DX-1 is unbalanced, I decided to run RCA out of the marantz into the DX-1 and then using XLR-RCA cables to the monoblocks.

Last time I had the DX-1 running, I was truly amazed at what it could do. This time was different. After getting everything connected and working and putting on Nora Jones, the High Frequency was absolutely amazing but the bass was completely lacking. The DX-1 is meant to provide a bitter bass extension as well as tighter bass, as logged in my previous posts about the DX-1 but that was all missing. I swapped out my DX-1 to my spare only to find the same issue. I even changed out my XA100's for a NAD208THX and it didn't fair much better.

I remember last time have the DX-1 working away with my Meridian 568.2MM processor was spectacular. I'm happy with the high pass section, in fact it's even way better than before but the bass is missing.

I'm going to have to go through everything again and see if I've missed anything. I though it might have been the XLR-RCA cables not being grounded correctly but tried a different with similar results.

I must be missing something somewhere. Will post back when I've tinkered a bit more.

[pasadena]

More Pics from the first DX-1

[pasadena]

Pics of the second DX-1. This seems to be stock. The only difference is the rubicon caps next to the transformer.

[Robh3606]

Hello Pasadena

Not sure what you are looking for but one set is obviously set up with CC capacitors. If you have the cards out can you put up a good sharp picture of the LF stock card so you can really see the backside foil pattern?

Rob

[Don C]

My XPL200s just failed with foam rot a few months ago. Check them out. Also I had a midrange fail on me recently. Listen to each driver with your ear close and make sure they all still work. Seems ovvious, but it still took me a few days to discover all of the problems.

[pasadena]

It seems to be bass deficient on both sides. The speakers play perfectly fine without the DX-1, it's only when the DX-1 is introduced that the lack of bass is apparent. There is a dial at the front of the DX-1 to increase bass output but I have to set it at around 90%, which to me is not right but the bass is fine at this dial point. When I had my DX-1 running a few years back, I remember never having the dial cranked up so high.

There is more bass saturation through the driver range without the DX-1. I know that introducing the DX-1 the bass was more tight. I'll have to keep figuring it out. I do paired spares for all the drivers except for the 2214's. Too costly to ship.

[Robh3606]

Did you remember to flip the biamp switch to the correct position??

Rob

[pasadena]

Did you remember to flip the biamp switch to the correct position??

Rob

Yes I checked all that. I'm always mindful when bi-amping that I don't do anything stupid or blow anything up, I'm good at doing that . I did have the switch on one speaker flicked to -2db and sat there ages for thinking why one speaker sounded different. Something simple as checking cords or switches can be easily overlooked.

I know Ti Dome has a DX-1 and would be interested to see what position the front dial on the DX-1 is set to? If its set do high like mine them its probably the characteristic of the DX-1, if not, <scratches head>.

I'll have to dig up my posts from GT about installing an op-amp on the low pass card for bass boost, anyone remember what and how to do that?