Hi Tizman,
I could not find any extra info regarding geometry, if you could use it in your application it would be great as it costs is very low.
Other problem is to find tube that will work with 25mA transformer maximum current. So maybe something like 6BM8 in triode mode...
Winding method in OT is most influential thing - if its not enough segmented/divided you would not get full freq. response.
There are better ones for sure on the market like Hashimoto or ISO/Tango if you could afford 200+ per piece...
I could not find any extra info regarding geometry, if you could use it in your application it would be great as it costs is very low.
Other problem is to find tube that will work with 25mA transformer maximum current. So maybe something like 6BM8 in triode mode...
Winding method in OT is most influential thing - if its not enough segmented/divided you would not get full freq. response.
There are better ones for sure on the market like Hashimoto or ISO/Tango if you could afford 200+ per piece...
Oh, one more thing, why not OTL amp without any output transformer issues?
Something like:
Mini Beast Single Ended Class A OTL
Something like:
Mini Beast Single Ended Class A OTL
On principle, I prefer to build with low cost parts if there isn't any adverse impact to doing so. With a regular OPT for a normal full range amp, there isn't often much choice but to lay out the big bucks to get great results. The nice thing about my particular application, where the amp doesn't do much over 400 HZ (my crossover is actually at 630 HZ), is that it appears that I can get excellent results from using two OPTs that would normally be considered of poor quality.
I have a pair of very disappointing, locally built, 25 watt per channel, single ended OPTs that have bad HF performance, but have very solid LF performance. These otherwise useless OPTs used for just LF, combined with a small and very inexpensive OPT for HF may produce a final result that is the same or better than the big money, full range OPTs that are currently available.
The 125ASE is $53.48 CAD. That is $120.86 CAD for a pair including taxes. That is mostly why I haven't already ordered the 125ASE. I purchased the small black ones that are pictured above for $44.37 CAD delivered.
Hi, I checked - measurement is done on 20dbu - or about 8 volt RMS - so not very realistic, still better then no data at all
The price in Holland is about 32,- Euro x 2 + shipping costs = about 70,- Euro for pair.
They are not as cheap as they used to be before... ( less than 20,- Euro 8-9 years ago )...
Only other cost effective option would be Transcendar transformers - provided they respond at all to the old e-mail address or make ordering in any way possible on their web site... :-( just unreal today that they don't want to sell their products!!!???
Transcendar Transformers - 5 Watt SE
The price in Holland is about 32,- Euro x 2 + shipping costs = about 70,- Euro for pair.
They are not as cheap as they used to be before... ( less than 20,- Euro 8-9 years ago )...
Only other cost effective option would be Transcendar transformers - provided they respond at all to the old e-mail address or make ordering in any way possible on their web site... :-( just unreal today that they don't want to sell their products!!!???
Transcendar Transformers - 5 Watt SE
By my calculation, I need to give my HF section .125 watts per channel to get the volume I want at my listening position. Hammond says that the 125ASE is good for 100 to 15K HZ +/- 1 DB at 3 watts. How would the 125ASE perform at .125 watts? I don’t care about the 100 HZ part, as I am crossing over at 630 HZ, but I do care about the HF extension. Isn’t the +/- 1 DB really more about the 125ASE dropping down 2 DB in the LF rather than in the HF? Is it safe to assume that at .125 watts, the 125ASE will still perform well in the HF?
Ok, I’ve read through this whole thread. Frankly, you have what are no doubt very well engineered and manufactured to very high standard 3 W Electraprints that Jack would have built to your application specific requirements when he built them. They will be at least 1 order of magnitude (probably more) better in terms of high frequency performance than any Hammond or whatever else you have bought from elsewhere. ALL YOU HAVE TO DO is simply size the input cap of your existing HF amp to high pass anything above400 HZ. That solves your problem, relieves the amp from having to deal with the lower frequencies and speculate with some confidence that it will sound very nice indeed. Frankly, i don’t understand why you want to use (relatively speaking) junk when you already have some very high quality iron that will perform at a very high level.
SoundContextAudio: The 3 watt Electraprints are for a different 45 tube amp project. The Electraprints will be used full range and with speakers that are also full range. This amp is for a set of speakers that are two ways with separate amps for each driver and either a passive or active crossover. I know that two ways with two amps and active or passive crossovers are not normal, but I see an opportunity for those people who do have a setup with separate amps for HF and LF to put something together with relatively inexpensive parts that might be just as good or better than a normal setup. Also, here in Canada, the choices for reasonable OPTs are slim. It’s pretty much Hammond or something from China. I bought my Electraprints used from a fellow DIY guy in Canada. Ordering a pair from Electraprint, or even from Edcor, is prohibitively expensive once exchange, duties and shipping are added on.
Hi Tizman,
Since you have couple of set's of transformers, you could just try them in-circuit and see how they perform, even if you are not going to use them.
You can always buy some other OT as funds permit, also you are in unique position to have working active tube system - not many have that luxury.
Regarding Hammond, their SE range is surely not hifi but they sound OK for what they cost, I would first test all of the transformers you have on the hand as you have already many of them.
Below picture is from Hammond 125DSE on the left and 125ESE on the right with 10KHz square wave, we all know which would be better for high-end.
Now compare that with 2nd picture - Tube/OTL amp output signal on same 10KHz - just so smooth without any ringing.
Since you have couple of set's of transformers, you could just try them in-circuit and see how they perform, even if you are not going to use them.
You can always buy some other OT as funds permit, also you are in unique position to have working active tube system - not many have that luxury.
Regarding Hammond, their SE range is surely not hifi but they sound OK for what they cost, I would first test all of the transformers you have on the hand as you have already many of them.
Below picture is from Hammond 125DSE on the left and 125ESE on the right with 10KHz square wave, we all know which would be better for high-end.
Now compare that with 2nd picture - Tube/OTL amp output signal on same 10KHz - just so smooth without any ringing.
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Depanatoru: I already have the black ones pictured in post #57 of this thread, they are 5K: 4/8 Ohm 3 Watts and are described as being “3 clips, 2 wound”, and I have another pair on order. I attached the screenshots of the description for the ones on order. They are the 8K:4/8 Ohm 3 watt, and are described as “4 clips and 3 wound”.
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Yes. I saw that as well. I was more concerned about the winding geometry than with the inductance because of my 630 HZ crossover point. I’m not sure exactly what “4 clips and 3 wound” means. Does that indicate that there is some sort of interleaving/segmenting done in the winding of these OPTs?
I have attached the rest of the description of them that I missed in my earlier post.
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What sort of choke do I need for parafeed? I’ve only looked at parafeed in passing. I have built a headphone amp with a 5998 That has a switchable OTL or transformer output, but haven’t built an OTL speaker amp.
Thank you for the clarification. You mentioned you had the EPs and they just seemed like the obvious choice from a quality and performance standpoint. It could be a fairly straightforward matter to switch in different low pass caps for the different applications should you choose.
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