An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
What can i expect fom this desgin as far as sound goes......i havent decided on iron yet, i know that will determine alot. I'm also palnning on using a preamp which uses 6267'a and a 12ax7. What voltage transformer would I need to supply 560 V after rectifcation for he plate voltage? 400-0-400 @300 ma?
Thanks
Jeremy
Frankly, the design doesn't thrill me. It runs way too close to Class "B". 60 W. from a PP pair of KT88s is "normal". Also, the paraphase topology splitter leaves much to be desired.
Eli,
Jeremy,
This circuit as it stands will have insufficient gain for line-level input - it definitely needs a preamp with a gain of ~12 dB.
Since there is no negative feedback (not enough gain for it anyway), it will have a low damping factor, quite a bit of distortion, probably a limited bandwidth and gain that will be very dependent on the individual tubes and their ages. Of course, some of that will depend on your OP transformer, as you say, as well as your speakers. I think UL is supposed to benefit from at least some NFB, if only 6 to 10 dB of it, but you'd have to add an input stage on the front to be able to achieve that.
Looks like a concertina splitter to me. The topology reminds me of a Williamson without the first stage.
Jeremy,
This circuit as it stands will have insufficient gain for line-level input - it definitely needs a preamp with a gain of ~12 dB.
Since there is no negative feedback (not enough gain for it anyway), it will have a low damping factor, quite a bit of distortion, probably a limited bandwidth and gain that will be very dependent on the individual tubes and their ages. Of course, some of that will depend on your OP transformer, as you say, as well as your speakers. I think UL is supposed to benefit from at least some NFB, if only 6 to 10 dB of it, but you'd have to add an input stage on the front to be able to achieve that.
Yes, it's a Williamson with its nose chopped off. Restore the nose and you'll be in with a chance. You'll need good output transformers to cope with the feedback needed to straighten out that Class AB output stage. Do you really need 100W?
Jeremy,
It seems I was fooled by balance circuitry into thinking the splitter is paraphase.
COSTLY, superior, O/P trafos are necessary for both the Williamson and H/K Cit. 2 circuits. Absolutely nothing wrong there, but if cost containment is a factor, DynaClone A431S trafos combined with a Mullard circuit will give you a lot of bang for your buck. If you use the Mullard circuit, put a 12AT7 (for its high gm and low Rp) in the phase splitter "hole".
BTW, the Mullard circuit has gobs of gain. So, a "unity" gain line stage is fine.
It seems I was fooled by balance circuitry into thinking the splitter is paraphase.
COSTLY, superior, O/P trafos are necessary for both the Williamson and H/K Cit. 2 circuits. Absolutely nothing wrong there, but if cost containment is a factor, DynaClone A431S trafos combined with a Mullard circuit will give you a lot of bang for your buck. If you use the Mullard circuit, put a 12AT7 (for its high gm and low Rp) in the phase splitter "hole".
BTW, the Mullard circuit has gobs of gain. So, a "unity" gain line stage is fine.
Using a more powerful tube is an option. GM70, 211, 813, ect. They run at a little big higher voltage so parts can get expensive.
Have a look at the 50W 3 stage version in the same book (cathode bias) and if you want 100W....drive the o/p stage in fixed bias at same B+500V and you'll be close in getting 100W at line in voltages and I'll swap the ECC82 driver for 6SN7....the ECC83 front end can be improved.
That version uses global nfb.....the paraphase splitter isn't that bad ?
That version uses global nfb.....the paraphase splitter isn't that bad ?
An externally hosted image should be here but it was not working when we last tested it.
this is a 30 Watt with either KT66 or KT88, I want to use the KT88. I have a trasnformer that just might work for this one.
Jeremy
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