Hi,
I'm about to build a SE-2a3 amp.
The only thing missing is the OPT and since my budget isn't that high my choice is limited.
So far I found 2 possible candidates:
1. One Electron UBT-3 ($75 at AES)
2. Lundahl 1664-60mA ($90 at Aquablue)
Does anyone have some experience with these OPT's ????
Jim
I'm about to build a SE-2a3 amp.
The only thing missing is the OPT and since my budget isn't that high my choice is limited.
So far I found 2 possible candidates:
1. One Electron UBT-3 ($75 at AES)
2. Lundahl 1664-60mA ($90 at Aquablue)
Does anyone have some experience with these OPT's ????
Jim
Hi Jim,
Pound for pound.. dollar for dollar.. the One electron is better than Hammond. The Hammond does sound very good, but it is $99. If you can get the OE for $75, it is the best bet.
I did some comparisons, both distortion and frequency response, and the Hammonds, when they say 30-30K, they mean it. No matter what I did I couldn't get it to extend further. Plus there is about 2-3% even order distortion (through the whole range) that is also plainly visible in a scope, and with NFB will not change.
The OE OTOH go from 5 to 45kHz (in the same circuit!), and the distortion is very low... without NFB! (using the 300B tube, that is. Don't know how it will perform with a 2A3). So, since you may not get more than 4 watts with the 2A3, I would go with the OEs, IMHO.
Now, if you can get Lundahls for $99.... Go for it! Since they are that low I will get them myself to see how they perform.
Gabe
Pound for pound.. dollar for dollar.. the One electron is better than Hammond. The Hammond does sound very good, but it is $99. If you can get the OE for $75, it is the best bet.
I did some comparisons, both distortion and frequency response, and the Hammonds, when they say 30-30K, they mean it. No matter what I did I couldn't get it to extend further. Plus there is about 2-3% even order distortion (through the whole range) that is also plainly visible in a scope, and with NFB will not change.
The OE OTOH go from 5 to 45kHz (in the same circuit!), and the distortion is very low... without NFB! (using the 300B tube, that is. Don't know how it will perform with a 2A3). So, since you may not get more than 4 watts with the 2A3, I would go with the OEs, IMHO.
Now, if you can get Lundahls for $99.... Go for it! Since they are that low I will get them myself to see how they perform.
Gabe
I have lots of experience with the PP Lundahl OPTs (as well as ITs, chokes etc), and really like them. As for thier SE stuff, I dunno, but if I were to build an SE, I would give them a go personally, based on my previous good experiences with their gear. The downside with Lundahl trannies, and something that's put some people off using them, is that they don't look like traditional transformers and can look ugly on top of a chassis. Mount them underneath, or find a cheap diecast Al housing to put them inside (not potted of course)jim said:Hi,
I'm about to build a SE-2a3 amp.
The only thing missing is the OPT and since my budget isn't that high my choice is limited.
So far I found 2 possible candidates:
1. One Electron UBT-3 ($75 at AES)
2. Lundahl 1664-60mA ($90 at Aquablue)
Does anyone have some experience with these OPT's ????
Jim
What I would caution you about, is shipping costs. USPS isn't a cheap postal service and I would contact AES for a shipping quote first, as it might raise the price significantly. Hammonds have the same problem unless there is a local distributor with decent pricing. Unless you have a high volume account with DHL etc, the costs there will be much higher again. Also get insurance. According to the catalogue, the UBTs are 6.1 lbs before packaging. I've had many good dealings with AES, and Benny at Aquablue has been very helpful.
Gabevee said:
What do you mean 'extend further'? There was a brick wall at 30k? What freq, and what wattage was your testing at?
Welcome to the world of output transformers. Again, at what level, what type of signal, and what amount of NFB?
I'm asking these questions, not to give you a hard time Gabe, but to be fair to Hammond - who I think are honest manufacturers with a solid product. A "review" like yours can start rumors, and may not be justified.
I happen to like and use Hammond iron all over the place.
But, in the 6L6 and 300B amps I make I used NFB to see if I could bring the response from 30-30K to 15 to as far up as it will go (as everyone knows NFB will do) before inherent capacitance rolls off the high end.
Power... both at 1 watt and full power. Sine wave. 10-24dB NFB.
Strangely enough, with the Hammond 125ESE, the 300B gave an impressive 40-15kHz response from an advertised (FWIW) 100-10K transformer with no NFB. NFB extended it down to about 25 Hz, just before beginning to roll off. Up to about 18kHz.
While I do expect even order distortion, I also expect a reduction when NFB is employed. With the Hammond 1628, there was little reduction.
However, to their credit, the sound is silky smooth and consistent. They are very well built. I highly recommend them for pentode and tetrode tubes for the UL tap one can take advantage of.
In fact, lately they have even become more asthetic. Hammond now seems to use a different flat black finish, a powder coat, and a smooth protective coat. Very pretty.
Gabe
But, in the 6L6 and 300B amps I make I used NFB to see if I could bring the response from 30-30K to 15 to as far up as it will go (as everyone knows NFB will do) before inherent capacitance rolls off the high end.
Power... both at 1 watt and full power. Sine wave. 10-24dB NFB.
Strangely enough, with the Hammond 125ESE, the 300B gave an impressive 40-15kHz response from an advertised (FWIW) 100-10K transformer with no NFB. NFB extended it down to about 25 Hz, just before beginning to roll off. Up to about 18kHz.
While I do expect even order distortion, I also expect a reduction when NFB is employed. With the Hammond 1628, there was little reduction.
However, to their credit, the sound is silky smooth and consistent. They are very well built. I highly recommend them for pentode and tetrode tubes for the UL tap one can take advantage of.
In fact, lately they have even become more asthetic. Hammond now seems to use a different flat black finish, a powder coat, and a smooth protective coat. Very pretty.
Gabe
OPT
Hi,
Actually before Benny Glass started his business he bought his OPTs from my former company.
At that time (1986-1995) not so much choice for decent OPTs was available and Benny used to buy Tango,Tamura or Rex OPTS as most other DIYers would have.
However,from a commercial and quality standpoint I would recommend the Lundahl especially since Benny seems to sell at even lower prices than Lundahl themselves.
(Dunno how he does it.)
If anything should be wrong with them (normally this should not be the case) you could easily return to Benny.
Importing heavy and delicate items such as OPTs is both expensive and risky.
Another alternative would be Automatic Engineering in Holland .
AE
An of course say hello to Benny from me,
Hi,
Actually before Benny Glass started his business he bought his OPTs from my former company.
At that time (1986-1995) not so much choice for decent OPTs was available and Benny used to buy Tango,Tamura or Rex OPTS as most other DIYers would have.
However,from a commercial and quality standpoint I would recommend the Lundahl especially since Benny seems to sell at even lower prices than Lundahl themselves.
(Dunno how he does it.)
If anything should be wrong with them (normally this should not be the case) you could easily return to Benny.
Importing heavy and delicate items such as OPTs is both expensive and risky.
Another alternative would be Automatic Engineering in Holland .
AE
An of course say hello to Benny from me,
Here is another source but I have no experience with them:
http://www.handwoundtransformers.com/se.html
http://www.handwoundtransformers.com/se.html
Brett,
I know what you mean. I bought a pair of the Hammond 125ESE's in spite of some negative reviews they got and was very pleasantly surprised by their performance. Of course, the Hammond 1628 series is far superior.
I am actually looking for a less expensive alternative to my "300B on a budget" kit, and these look pretty enough.
My first experience with SE a few years ago was with a pair of what looked like vertical output transformers from TV. A few guys at rec.audio.tubes said they make real good cheap alternatives because of their needing to be very linear. Of course, no one makes them anymore since tubes went out of vogue in TVs.
But again, a far cry from the 1628s.
I will keep all posted. In fact, I am going to have something like a shootout with pictures, etc.
Gabe
I know what you mean. I bought a pair of the Hammond 125ESE's in spite of some negative reviews they got and was very pleasantly surprised by their performance. Of course, the Hammond 1628 series is far superior.
I am actually looking for a less expensive alternative to my "300B on a budget" kit, and these look pretty enough.
My first experience with SE a few years ago was with a pair of what looked like vertical output transformers from TV. A few guys at rec.audio.tubes said they make real good cheap alternatives because of their needing to be very linear. Of course, no one makes them anymore since tubes went out of vogue in TVs.
But again, a far cry from the 1628s.
I will keep all posted. In fact, I am going to have something like a shootout with pictures, etc.
Gabe
Hey Joel,
I tend to disagree. In fact that is why one would want to take the NFB from the secondary taps. The distortions fed back including the ones from the transformer are inverted, which then add to the open loop distortions to make less distortion.
Basic NFB theory. Unless I misunderstood what you wrote.
Also, I was referring to what the transformer itself had on it as the freq response. Go figure. Manuals and catalogs are written by different people than engineers. There can be differences in documentation.
On the bench also I measured 100-10kHz before roll off with the transformer by itself, with an 8 ohm load resistor at the 8 ohm tap. That is, 8 ohm with 3K as the primary.
Gabe
I tend to disagree. In fact that is why one would want to take the NFB from the secondary taps. The distortions fed back including the ones from the transformer are inverted, which then add to the open loop distortions to make less distortion.
Basic NFB theory. Unless I misunderstood what you wrote.
Also, I was referring to what the transformer itself had on it as the freq response. Go figure. Manuals and catalogs are written by different people than engineers. There can be differences in documentation.
On the bench also I measured 100-10kHz before roll off with the transformer by itself, with an 8 ohm load resistor at the 8 ohm tap. That is, 8 ohm with 3K as the primary.
Gabe
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