I'm currently using a LL1660/5mA in 1:1 in my 26 preamp. I have filament bias right now but I could also use battery bias at some point - I tried that in my 10y preamp and it sounded fairly similar. Anyway, I'm loving the LL1660.
So I have a question for the 26 community. There are more choices in plate chokes for the 26 than there are in output/interstage transformers.
What is available besides the LL1660 in transformers? I can't think of anything obvious, and some builders of 26 preamps might want - for example - to consider the availability of cheaper transformers at the expense of a compromise (big or small) in sound. Edcor do a 15K:15K
Other builders may want something more sophisticated - nickel, amorphous etc.
Any ideas for transformers the 26 would be happy with? I'm guessing at least 150 Henries
Andy
On the vintage side both UTC HA-133 and UTC A-25 15K:600 work well.
Electra-Print will custom build OPTs for the 26/01 as well.
Magnequest made excellent 10K:600 and 20K:600 OPTs. (Both have sufficient primary inductance for use with a 26 or 01)
Hashimoto HL-20K-6 (20K:600) for 26/01
Hashimoto HL-10K-6 (10K) which is probably a better match for the 12/112 due to its primary inductance of 95H.
Sowter doesn't appear to make anything with sufficient inductance for use with a 26.
AE might be persuaded to custom make an appropriate transformer, but does not appear to offer anything directly suitable.
In the Lundahl line the LL1660/10mA appears suitable when configured as a 4.5:1 step down.
Bartolucci line stage models A, B and F could also be used. (While my experience with Bartolucci is limited, the few I have worked with were excellent.)
Trafomatic may also make suitable transformers, but lists none on their site so they would have to be contacted. (They also make excellent transformers)
Iso Tango NP-126 may be suitable, no idea what the primary inductance is however.
James, and Tamura would be other likely sources as well.
None of these are particularly cheap either...
Edcor (a custom type, not OTS) or Electra-Print are likely to be the most economical choices.
Electra-Print will custom build OPTs for the 26/01 as well.
Magnequest made excellent 10K:600 and 20K:600 OPTs. (Both have sufficient primary inductance for use with a 26 or 01)
Hashimoto HL-20K-6 (20K:600) for 26/01
Hashimoto HL-10K-6 (10K) which is probably a better match for the 12/112 due to its primary inductance of 95H.
Sowter doesn't appear to make anything with sufficient inductance for use with a 26.
AE might be persuaded to custom make an appropriate transformer, but does not appear to offer anything directly suitable.
In the Lundahl line the LL1660/10mA appears suitable when configured as a 4.5:1 step down.
Bartolucci line stage models A, B and F could also be used. (While my experience with Bartolucci is limited, the few I have worked with were excellent.)
Trafomatic may also make suitable transformers, but lists none on their site so they would have to be contacted. (They also make excellent transformers)
Iso Tango NP-126 may be suitable, no idea what the primary inductance is however.
James, and Tamura would be other likely sources as well.
None of these are particularly cheap either...
Edcor (a custom type, not OTS) or Electra-Print are likely to be the most economical choices.
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Wow!! That's really useful. I'm shooting for 1:1 and short leads to the amp, or even put the first stage in the amp itself, simply because I only use DHTs with low mu and so gain is too precious to sacrifice. I know Thomas and yourself and conventional practice favour stepdown and higher mu tubes in the amp, but that's not the application I need here, which effectively is an interstage. I'm probably happy with the LL1660/5ma but I'm really curious about alternatives.
This may then be a question of a custom made unit if it's 1:1 since most of the above list are 600 ohm output. You wouldn't normally use a 26 as a driver, so interstages rarely go up that high in Henries.
You can't help getting a bit excited at the Japanese exotica, though....... Mmmmm. But as you say, expensivo.
Andy
This may then be a question of a custom made unit if it's 1:1 since most of the above list are 600 ohm output. You wouldn't normally use a 26 as a driver, so interstages rarely go up that high in Henries.
You can't help getting a bit excited at the Japanese exotica, though....... Mmmmm. But as you say, expensivo.
Andy
Dave Slagle, who posts here sometimes, also makes custom chokes and transformers. Made some massive chokes for a 801 parafeed amp of mine. They measure and sound good.
Sheldon
Hmmm. Interesting. I was thinking 150H was the minimum for a 26.
I just hooked up two 156C Hammonds in series as plate chokes. Twice 150H should give 300H I assume. Sounds remarkably pleasant for a cheap solution. Doesn't quite have the magic of the LL1660 which is a bit special, but nevertheless the sound is all there - clean and clear. I used battery bias. Output caps were Teflon FT-3. I'll also try some Russian 0.1 silver mica when I can. Haven't compared those directly and that would be worth knowing.
andy
I just hooked up two 156C Hammonds in series as plate chokes. Twice 150H should give 300H I assume. Sounds remarkably pleasant for a cheap solution. Doesn't quite have the magic of the LL1660 which is a bit special, but nevertheless the sound is all there - clean and clear. I used battery bias. Output caps were Teflon FT-3. I'll also try some Russian 0.1 silver mica when I can. Haven't compared those directly and that would be worth knowing.
andy
Hi Andy,
all Tango Transformers have surprisingly low primary inductance for the intended applications yet sound remarkably good, especially in the bass.
Generally I also prefer to have higher inductance. Especially in the linestage I want the roll off not to start too early.
I also like the LL1660 a lot. Although it really sounds best in 4.5:1
If you don't have to adjust your volume pot all the way up for average listening and have some margin in gain, I do encourage you to just try this. It is just a few solder joints and reversed in a few minutes. I'm sure you will be pleasantly surprised! See I try hard to convert you on this point
Coming back to the NC20: This one is sound wise in another league alltogether! However just 1:1, so only for interstage use.
As step down transformers I also tried Tango NP8. Here I clearly prefer the Lundahl 1660/4.5:1! Even in my most elaborate directly heated linestages I use the Lundahl.
Best regards
Thomas
all Tango Transformers have surprisingly low primary inductance for the intended applications yet sound remarkably good, especially in the bass.
Generally I also prefer to have higher inductance. Especially in the linestage I want the roll off not to start too early.
I also like the LL1660 a lot. Although it really sounds best in 4.5:1
If you don't have to adjust your volume pot all the way up for average listening and have some margin in gain, I do encourage you to just try this. It is just a few solder joints and reversed in a few minutes. I'm sure you will be pleasantly surprised! See I try hard to convert you on this point
Coming back to the NC20: This one is sound wise in another league alltogether! However just 1:1, so only for interstage use.
As step down transformers I also tried Tango NP8. Here I clearly prefer the Lundahl 1660/4.5:1! Even in my most elaborate directly heated linestages I use the Lundahl.
Best regards
Thomas
Hi Andy,
there is much more than primary inductance which has an influence on the overall result. The primary inductance determines the bass roll of frequency. Just increasing the inductance endlessly would create other problems like increased winding capacitance and impact high frequency roll off. Tango generally tends to concentrate on a wider bandwidth in the treble.
4.5:1 is a totally different application than 1:1 so this is not really comparable. The 1660 can only be sensibly compared to the Tango when it is configured 1:1.125 (or the other way around). In this configuration the Tango sounds and measures better than the Lundahl.
Thomas
there is much more than primary inductance which has an influence on the overall result. The primary inductance determines the bass roll of frequency. Just increasing the inductance endlessly would create other problems like increased winding capacitance and impact high frequency roll off. Tango generally tends to concentrate on a wider bandwidth in the treble.
4.5:1 is a totally different application than 1:1 so this is not really comparable. The 1660 can only be sensibly compared to the Tango when it is configured 1:1.125 (or the other way around). In this configuration the Tango sounds and measures better than the Lundahl.
Thomas
I am in contact with AE-Europe in the Netherlands to make a custom build #26 HighEnd plate to line Transformer.
Let´s see what they could do for the #26 community
- 15K:600Ohm nominal Z ratio
- 200H prim. / 8-10ma DC prim. current
- 250Vdc max. prim. voltage
- doulbe C-Core (amorph or permalloy)
- max. bandwith (in the window of 10-70 kHz @-3dB or better)
- good shielded
- copper and silver sec. possible
Let´s see what they could do for the #26 community
Don't focus too much on these absolute inductance specifications.
The values measured with inductance meters, especially in the case of grain oriented silicon steel, give merely an approximation of what is really going on.
I would say that another spec, DCR of windings, is also very important (copper losses).
Compare two chokes (or IT's) with the same inductance and DC current capability, but different DCR's, and I bet you'd prefer the lower DCR one.
For DCR I try to go not over 10% of the tube Rp.
The values measured with inductance meters, especially in the case of grain oriented silicon steel, give merely an approximation of what is really going on.
I would say that another spec, DCR of windings, is also very important (copper losses).
Compare two chokes (or IT's) with the same inductance and DC current capability, but different DCR's, and I bet you'd prefer the lower DCR one.
For DCR I try to go not over 10% of the tube Rp.
Thanks Pieter, that's a helpful insight. Your expertise is appreciated!
I like the idea of a "26 community". Since I don't know of any finer small tube and since fortunately they made loads of them it would be good to think that we might at last have a voice. We might be drowned out by the 12AX7 community but at least we could be "a contender"....
Andy
I like the idea of a "26 community". Since I don't know of any finer small tube and since fortunately they made loads of them it would be good to think that we might at last have a voice. We might be drowned out by the 12AX7 community but at least we could be "a contender"....
Andy
Keep on dreaming...
If Bartolucci could make it for all their Preamp. Transformers.....
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...i think AE-Europe could do it also.
Puhh... Why so agressive
I share only my ideas to the wanted transformer. If AE said the frequency window is smaller, it´s also ok.
I´m only trying to get an non compromise OPT for me and the #26 community, that´s all!
BTW, i find your comment about Japan not funny!
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