Andy I used as step down (not very good) & plate choke (better but not very good). Best way to get full available output with Ale's Moglia Hybrid Mu-Follower.
It's probably due to the reason they want to put their dual coil topology everywhere, which isn't a benefit only topology, as nothing is in transformer design. Dual coils can bring coil to coil and coil to core to coil capacitances, which together with coil to coil leakage inductances can bring additional resonances. These are specifically dip resonances and are mostly pronounced when the higher impedance layers are the outside ones and when there is a high interwinding to secondary capacitance difference between two primary sections.
Worst case with dual bobbin transformers is when the whole primary and/or secondary layers are first interconnected within the first whole bobbin, then transferred to the second half instead of distributing gradually each primary layer. The later takes a lot of more labor to do. The first way works well for PP design though, due to the center primary ground which ensures the capacitances in both halves are equal, hence no potential capacitance bridging. But the first way has high primary to primary leakage when the PP amplifier goes to class B. And bla bla and so on.
Completely agree on Lundahl. Their input transformers are decent, as are their OPT. Interstages I will never use again. The strays are untameable, even with low Rp drivers (like a 6W6 or 46), and they have some wild phase shifts that make serving a P-P output stage unbalanced between the legs. This goes for the 1692A in my experience as well.
No doubt Lundahl will work reasonably well as choke loads, since the tube can accommodate +/-20% impedance load vs frequency and still produce a suitable output voltage to drive the next stage. A completely different situation when using as an interstage.
Not trying to bash Lundahl; I still use them as output transformers in my 12B4A preamp (1689AM/PP if I recall), but they are not universally wonderful. For that matter, I will never use Onetics again. I bought into the hype and was let down.
No doubt Lundahl will work reasonably well as choke loads, since the tube can accommodate +/-20% impedance load vs frequency and still produce a suitable output voltage to drive the next stage. A completely different situation when using as an interstage.
Not trying to bash Lundahl; I still use them as output transformers in my 12B4A preamp (1689AM/PP if I recall), but they are not universally wonderful. For that matter, I will never use Onetics again. I bought into the hype and was let down.
I haven't had any luck with Lundahl's input transformers - the LL1540 is quite bad sounding for example. The only Lundahl I really like from what was quite a large collection is the LL1682/50mA which I use with a 300b. That one is really nice, much better than the LL1664 which on paper should suit the 300b better.
But O-Netics is a different story. I have Bud's 3.5K Wright Sound SE outputs and they're lovely. Listening to them as I type. My pair of Level 1 3.5K SE OPTs are nice too. I don't believe much in break-in but i even think they're improving with age.
We know you have great taste
monolith vs new tango that's the problem
The NC-20 (both the old type and ISO-Tango) is really a great IT for SE:SE. It works fine with a great variety of driver tubes with plate resistance from 1K to 5K. It's often considered as a reference by other manufacturers. If you can afford a pair, can find for sale and buy them you will never regret it.
Monolith makes great products but I have no experience with their SE interstages. The bifilar PP
P IT02 is very good. I have no idea of the current Tango production but there is an "alternative" to the NC-20. It's the Hashimoto A-305. To be honest all Hashimoto interstages are great from the smaller A-107 and A-105 through the A-115 and finally the A-305.
Both the A-107 and A-105 are also great for SE
P drive. Not many alternatives there, to be optimistic.....once I asked Monolith if they were willing to make a SEP IT and they declined because they want their IT's to go well beyond 100KHz but in my opinion it's more academic than practical. This is the most difficult kind of IT to get right.Then also 50AE here in the forum, I am told he can make excellent interstages.
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3-stages integrated amplifier. Many types can be used both DC coupled (especially if one has a 400V+ rail) and RC coupled. I built the amplifier some years ago for a friend of mines. I think he settled on the ECC40 in the end.
Only real "issue" with that amp was the weight but many good amps have that problem.....
One solution can be pp:se x gain ,with dualmono balanced dac ...a lot of voltage
PS
Or as 45 but with 2x46 with pp:se ??
I have four 10Y
but not simple IT maybe
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I have four 10Y
For SE
P with 10Y driver:You could use the A-105 if don't need a lot of swing. This transformer can work with DC current up to 15 mA and it will be fine with 5K source impedance. The inductance is rated for 7 mA at 60H (small signal) and will be about 75H with medium-to-large signal. With 15 mA inductance will decrease to about 50H and 60H, respectively. The max output voltage SE
P drive you can get at 20Hz with anode current at 15 mA is 226V grid-to-grid (or 80 Vrms if you like). I would not use less than 5K because it would start peaking.On the contrary the A-107 is rated for 7K source impedance and the high frequency response is more controlled. That means it will become like the A-105 if use lower source impedance down to 3.5-4K which is a good thing. However this one works best with lower anode current (smaller tubes) around 5-8 mA but ratio is 1:1+1. The output voltage can be high but not suited for A2 or AB2.
For SE:SE the 10Y would work well with both A-115 and A-315. It would have more gain than the 46.
I have thought in the past about PP drive for SE power stage but in the end you need 2 tubes to drive the transformer just as you need 2 tubes for a 3-stage amplifier.
I've just been to the Monolith Magnetics website, and I have to say it's flippin' BS...which means that I'm really glad I got off of that ride. Nothing focused, everything multi-optioned..am I missing something? Is there really anything good there other than the tech hipe? Sorry to be a doubter, but go ahead and prove me wrong. ACK ! ! !
Best, Robert
Best, Robert
Well, you don't know until you test. To test you need to buy. Or you have to rely on other people's opinions. And all are subjective.
Monolith has done very good, tedious work. They have the finished looks and aesthetics, which is commercially quite hard. They also update their datasheets and seem to constantly learn and update.
Their prices are on the high-end side, but nothing wrong with that if they deliver good performance. And performance means good audio experience.
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Hi 50AE,
I've tried in the recent past to place a request for quote for a custom power transformer, to power a Thomas Mayer Sound Processor, with no luck using the standard request form at Monolith Magnetics.
I understand your logic, and I have just submitted a different request to MM to a specific individual there (Yves) with the details of my request. We shall see what we shall see.
I'm trying.
Best,
Robert
I've tried in the recent past to place a request for quote for a custom power transformer, to power a Thomas Mayer Sound Processor, with no luck using the standard request form at Monolith Magnetics.
I understand your logic, and I have just submitted a different request to MM to a specific individual there (Yves) with the details of my request. We shall see what we shall see.
I'm trying.
Best,
Robert
Magnequest is very difficult to work with these days. I have wanted to try a pair of his output transformers for a few years now, but was never able to get him to respond to any of my requests. I even followed his odd protocol of making the request via public post on his forum on audioasylum.
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Apart from specific situations, I think all transformers manufacturers will not pay attention to individual requests for a single piece or few pieces, right now. They all likely have a considerable backlog in production due to COVID.
Some even went into more serious troubles (see Sowter, for example).....
Some even went into more serious troubles (see Sowter, for example).....
I just got a pair of SE OPTs, 5K 50mA, made by Techno. They were used on eBay, but I think a special order. Techno are in Swindon UK. They say they do special orders. Looks like they make the OPTs for the revival Radford amps judging from the photo on their site. Should be a recommendation.
Audio Transformers - Techno Transformers
STA15/25 Reissue – Radford Revival
Audio Transformers - Techno Transformers
STA15/25 Reissue – Radford Revival