Anybody planning on buying a pair to try out? I have not the test equipment anymore to prove them but would be interested in picking up a set. Maybe I could grab a pair and send them to someone willing to run them through the ringer?
Tube Amp Parts - Output Transformers - AnTek Products Corp
We just put an offer on a house (which was accepted!!!) So once we find out how everything goes with escrow and our out of pocket expenses I may want to grab a set.
I'm particularly interested in the 5k, 15 watt unit. They are 1db down at 10khz, 3db down at 20khz. Seems plenty workable. Maybe even running 4ohms on the 8ohm tap, for 2.5k would give even better response? As it is they might be a good fit for a pair of EL86 or parallel pair of 6V6 triode connected.
Tube Amp Parts - Output Transformers - AnTek Products Corp
We just put an offer on a house (which was accepted!!!) So once we find out how everything goes with escrow and our out of pocket expenses I may want to grab a set.
I'm particularly interested in the 5k, 15 watt unit. They are 1db down at 10khz, 3db down at 20khz. Seems plenty workable. Maybe even running 4ohms on the 8ohm tap, for 2.5k would give even better response? As it is they might be a good fit for a pair of EL86 or parallel pair of 6V6 triode connected.
To be perfectly honest I almost would think that they didn't know how to test them correctly.
Like I said, I'm pretty curious, given that their power transformers perform very well as outputs I would like to see how their actual for-the-purpose outputs would do, with the extra taps they have available.
Maybe these would do well?
One of these per channel to a parallel pair of russian 6V6 with a 4 ohm load on the 8 ohm tap, or pentode connected 12AV5GA with the same load arrangement may be an interesing project. I have a 240 volt (120v X2) 150VA power toroid already with an added pair of 6 volt and a single 14 volt winding that I have been wanting to build up into a project for a while, would be nice to go all toroid.
The 40 and 60 watt models look iffy, I wouldn't buy them if they actually match their frequency response graph.
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The one worry is that if they have the low frequency performance that their website suggests (flat to 10 Hz), at a relatively small size then that would indicate more turns, which could make for a very large shunt capacitance. Depending on what their source is for testing, they could be running into an issue with that. Resistivity load should, theoretically, give a relatively flat frequency response.
My strong suspicion is that they are using a fairly standard M6 tape-wound core, and they probably don't make them in-house. Nothing inherently wrong with that, we've designed some very good pulse transformers around such cores.
Honestly.. for this price... you folks in the US could try out the cheapest one. It won't be as bad as using a power transformer.
It would probably be decent enough for a project that could be sold. Last ditch use scenario would be a guitar amp.
If I was still travelling for business (to the US) I would seriously consider a couple of the mp-10w80's in my "regular" order.
It would probably be decent enough for a project that could be sold. Last ditch use scenario would be a guitar amp.
If I was still travelling for business (to the US) I would seriously consider a couple of the mp-10w80's in my "regular" order.
yeah.. I just can't believe that weird HF response... and if it really is that bad, I would return it them with suggestions on how to improve it.
ok... 3dB loss from 10k to 20k.. maybe I could find a way to "fix" that in an amp as well. hehe...
For some lucky US diy'er this could be a nice little opportunity. I'm out since shipping makes it not interesting to here.
Caveat: No idea if there are other problems, especially ringing, or horrible capacitances as you indicate, but It might be fun and they would (should) appreciate the effort.
ok... 3dB loss from 10k to 20k.. maybe I could find a way to "fix" that in an amp as well. hehe...
For some lucky US diy'er this could be a nice little opportunity. I'm out since shipping makes it not interesting to here.
Caveat: No idea if there are other problems, especially ringing, or horrible capacitances as you indicate, but It might be fun and they would (should) appreciate the effort.
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That's what I was thinking, and I suspect it might be partially caused by their push for the low frequencies. Even the Edcor CXPP transformers aren't flat to 10 Hz, and apparently these are. In order to get that without a massive core you end up needing a lot of turns on the primary.
What would be nice is if OPT manufacturers would stop pushing for the lowest possible frequency response and start looking at making their transformers less squirrely at the top end. I don't really care if my amp can reproduce 20 Hz perfectly, but the better the HF performance the easier it is to get the feedback loop stable.
They may have just loaded with 8 ohms, and driven it with a voltage source. Low frequency roll off due to finite primary inductance won’t even show up. Drive with a current source (high impedance) and behavior could be quite different. Test at full power, and it would be different as well.
