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Old 17th September 2002, 11:34 PM   #11
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Default Heuh?

Dice,

I'm afraid I'm a bit at a loss here:

Quote:
Except the right piece of wire
I'm just guessing,do you mean comparing the sound of the Jensen MC stepups to a piece of (ok ,good quality) wire?

Also,while we're at it:

I notice the Jensen you have come in two versions at the same price only differing in turns ratio?

"The JT-346-AX is designed to be incorporated into custom moving coil preamp designs. It provides a perfect impedance match for premium low noise amplifiers like the AD797. It works best with cartridges that meet the criteria for either the JT-34K-DX or JT-44K-DX. The JT-346-AX may be wired with the 3 primary windings in series or in parallel to accomodate both general impedance ranges of moving coil cartridges. It does not have the higher step-up ratios of the the other Jensen transformers though, so is not normally suitable for use directly with a conventional RIAA preamp, except in the case of very high output cartridges."
JT-346-AX $ 25:600 1:4 +4dBu 0.015% <0.001% -0.05dB/
-0.03dB 220kHz
JT-346-AX $ 3:630 1:12 -5dBu 0.015% <0.001% -0.05dB/
-0.03dB 220kHz

Am I correct in assuming this one isn't particalurly suited to the lower output MC's?
Any idea how the other two models sound?
I need drop down transparency from my MC all the way through,any veiling and the thingies go to the sin bin (indefinitely).

Thks,
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Old 18th September 2002, 01:05 AM   #12
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Default Re: Heuh?

Quote:
Originally posted by fdegrove
Dice,

I notice the Jensen you have come in two versions at the same price only differing in turns ratio?
Yes. Notice that they say it can be used with cartridges which meet the criteria for either the 34K-DX or 44K-DX. Look up higher and it'll show you the criteria for each of those. What they mean is that depending how you wire the primaries, you can use it for either set of criteria.

Quote:
Am I correct in assuming this one isn't particalurly suited to the lower output MC's?
Not on its own. It's intended to be used in an MC preamp where additional gain is provided by active circuitry.

The others, with their 1:37 step up, provide all of the voltage gain and are intended to be plugged straight into the input of a MM phono stage.

Quote:

Any idea how the other two models sound?
I need drop down transparency from my MC all the way through,any veiling and the thingies go to the sin bin (indefinitely).
Dice will have to help you there. I'm still digital.

se
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Old 18th September 2002, 01:47 AM   #13
jcarr is offline jcarr  United States
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I've tried a number of MC stepup transformers (Lundahl, Jensen, Tango, Kanno etc.) Indeed, the better ones sounded quite good. But to me they didn't sound as revealing as the best discrete headamp circuits that we were able to come up with.

I felt that there was a noticeable filtering out of information with the transformers which the headamp didn't have. OTOH, you could also say the transformers cleaned up the sound and organized it.

Depending on what phono equalizer followed, sometimes the results were better with the transformer, and sometimes the results were better with the headamp.

However, I felt that the best sound was obtained by combining the best headamp circuit that I was able to devise with the best phono equalizer circuit that I was able to make.

Caveat: While the best headamp circuit sounded better to me than the transformers, I have heard many headamp circuits that didn't sound nearly as good as a decent transformer. As always, implementation is a major issue.

YMMV, jonathan carr
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Old 18th September 2002, 02:02 AM   #14
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Default Transformers Are Good

Steve,
On my workbench reference system I have a 1:1 transfomer isolation box between my preamp and power amp.
I also incorporated DPDT switches wired as reversing switches on the primaries to give selectable audio polarity.
Even though I am using as cheap as I can find car audio Taiwan made signal trannies, the system sound is very good indeed, and the polarity switching is a must in my opinion/experience.
Polarity switching is a mandatory feature I reckon, and applicable to your product.

Eric.
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Old 18th September 2002, 02:19 AM   #15
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Default MC TRANSFORMER

Jonathan,Steve et all,

I appreciate your input.
Reading you Jonathan,and especially knowing and greatly respecting the cartridges you helped to design, I think I read you well.
This convinces me more to pursue my quest to design the mere impossible:designing an integrated tube headamp fed by a battery PSU.
IMHO this combination has the potential of avoiding compromises so often found in most commercial designs.
Whatever hurdles I come across will be posted here ( the basics have been in service for five years and have baffled many a dyed in the wool audiophile) and after resolving all, the circuit diagram will be made available to the community.
And I have this gut feeling that Bernhard and others are just waiting for a "tranny" beater??

Yrs sincerely,
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Old 18th September 2002, 02:38 AM   #16
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Thumbs up ABSOLUTE PHASE

Hello,

You may find absolute phase may differ from one recording to the other.
According to the actual phase respect of your current system it may or may not be respecting absolute phase irrespective of its source.
This reminds me of the Counterpoint SA PI,which did the same actively (tube circuit).
Some people are more sensitive to it than others I've been told but it sure does make a lot of difference to most.
And yes that's a very good idea to incorporate in an isolation transformer.Geeh...are we really that slow to see the obvious?
Excellent idea!Five star and the economy award to you.
Introducing a DPDT switch, a piece of wire and some soldering can't up the price too much?
Steve?
Brilliant! Whish I thought of that.

Cheers,
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Old 18th September 2002, 02:52 AM   #17
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Frank, thanks for the compliments and the award.
The transformers that I used are intended for car audio line level DC isolation, and come mounted in a small box with RCA leads attached and cost AUS$12.00 wholesale.
These are cheap Taiwan transformers but they do a fine enough job.
I have not tried Jensens so I cannot comment on sonics differences.
IMO a hi-fi is not worth having without polarity switching, so this was/is my budget soloution.
The only precaution is that the secondaries need to be loaded down to avoid HF peaking response.

Eric.

PS - If you hang around you'll get to hear a few more gems like this on the forum from time to time.
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Old 18th September 2002, 04:04 AM   #18
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Default Re: ABSOLUTE PHASE

Quote:
Originally posted by fdegrove
Introducing a DPDT switch, a piece of wire and some soldering can't up the price too much?
Steve?
Brilliant! Whish I thought of that.
This reply goes out to mrfeedback as well.

No, it wouldn't up the price too much. Which is why I included a DPDT switch to change polarity (you can see them in the internal photograph in the EtM review, they're the blocky looking things on the far sides of the board next to the transformers).

However the switches aren't accessible from the outside. I intended them to be used as a set-it-and-forget-it so users could use it for reversing the polarity of the component that's feeding the InterFace in the event that the component inverted polarity.

Because the InterFace should be mounted as close as possible to the inputs of the component it's feeding, it wouldn't always be practical to get at it on a consistent basis as one would need to do if they're changing polarity from recording to recording.

Besides, any preamp worth its salt should have a polarity switch already.

Nevertheless, thanks for the comments!

se
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Old 18th September 2002, 04:31 AM   #19
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Default Re: MC TRANSFORMER

Quote:
Originally posted by fdegrove
This convinces me more to pursue my quest to design the mere impossible:designing an integrated tube headamp fed by a battery PSU. IMHO this combination has the potential of avoiding compromises so often found in most commercial designs.
What you might consider is getting the best of both worlds.

As I mentioned previously, the Jensen 346-AX is intended to be used in a circuit which uses active circuits to provide additional voltage gain. To that end, the 346-AX doesn't offer nearly as much voltage gain as the other two.

The more a transformer has to step up the voltage, the more compromises have to be made and the more its ultimate performance is sacrificed. Of course this applies to active circuits as well.

This may explain some of the dissatisfaction by some of wholly passive solutions where the entire burden is on a singular device.

With a hybrid, you get a little gain passively from the transformer and you get a little gain actively from the tube stage. Then neither has to work quite as hard if each were used on their own. Not to mention that the trannie will give you common-mode noise rejection far exceeding anything any active circuit can give you.

One of my personal design philosophies has been to avoid extremes and work to achieve a pleasing balance between compliments. It's been quite successful so far me. At least according to what my Zen Hedonist side tells me.

Quote:
Whatever hurdles I come across will be posted here ( the basics have been in service for five years and have baffled many a dyed in the wool audiophile) and after resolving all, the circuit diagram will be made available to the community.
Great! I hope whatever route you take leads to success!

Quote:
And I have this gut feeling that Bernhard and others are just waiting for a "tranny" beater??
Aren't there laws against trannie beating? If not, there outta be!

se
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Old 18th September 2002, 12:42 PM   #20
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Default TO TRANNIE OR NOT TO TRANNIE ?

Folks,

Thanks for the input.
Guess it's all a matter of doing the ultimate balancing (no pun intended) act,right?

However regarding the ISO trannies:
Absolute phase of the entire system is one thing to get right surely.
But I think Eric means he must have a way to check and control absloute phase of his media (CD,vinyl etc.).
It's a shame but all too many recordings are made with absolute phase reversed.
And no,I don't even want to think about all those multi miked acrobacies where they didn't even bother to check each feed's input phase...

Up to you Steve to put that switch on the box where it can be reached.

Rgds,
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