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Old 5th November 2003, 07:31 PM   #1
Raj1 is offline Raj1  United Kingdom
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Default good simple SE circuit please

Hi,

Anyone know of a simple SE amp schematic (no negative feedback) that sounds really nice, with DH tubes? Parts should be readily available in the UK.....

I'll consider OTL but quite honestly I'm a bit sceptical of using DC coupling caps as I feel they kill the sound.........

Thanks
Raja
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Old 5th November 2003, 11:17 PM   #2
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Hi,

Quote:
Anyone know of a simple SE amp schematic (no negative feedback) that sounds really nice, with DH tubes? Parts should be readily available in the UK.....
Neither frighten me...what outputtube do you have in mind?

Quote:
I'll consider OTL but quite honestly I'm a bit sceptical of using DC coupling caps as I feel they kill the sound.........
Caps have progressed no end over the past ten years and if must be we can lose that one too...

Tell us what yu have in mind,
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Old 6th November 2003, 05:22 AM   #3
SHiFTY is offline SHiFTY  New Zealand
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You could try the direct coupled Loftin-White 2A3 amp at the fi primer here

I have built this and it does sound pretty good. I used 6B4G though. Only problem is the power transformer-you need quite a high B+... The EZ 2A3 at www.angela.com sounds pretty good to me too and can be made with whatever power transformer is lying around.

The output transformers make the biggest difference. The Hammond 125ESE are ok to start with, but get better iron and you won't look back.
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Old 6th November 2003, 12:42 PM   #4
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Any one can provide KT88 single end circuit or KIT?
I have done my 300B SE, so I want to try KT88.
Thanks
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Old 6th November 2003, 01:16 PM   #5
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Raj
Quote:
Anyone know of a simple SE amp schematic (no negative feedback) that sounds really nice, with DH tubes? Parts should be readily available in the UK.....
you mean the whole amp being dht? or just the output stage?
i built a 5842 ccs into a fixed bias 2a3 parafeed 2.8k:8 sound not to bad. The layout is available at my website. I think components values are not yet included yet. At the moment using a 6j9 as the input stage.

Quote:
Any one can provide KT88 single end circuit or KIT?
you could mod the 300b to include the kt88. output trans should be the same. just the biasing points are different . B+ of 420 and -42 sounded good for me into a 2.5K:8 trans
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Old 6th November 2003, 04:06 PM   #6
zobsky is offline zobsky  India
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Quote:
Originally posted by audionote
Any one can provide KT88 single end circuit or KIT?
I have done my 300B SE, so I want to try KT88.
Thanks

what difference in sound would i expect using a kt-88 vs a 300B in SE configuration? ... kt88 tubes being quite cheaper than 300B tubes?
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Old 6th November 2003, 05:21 PM   #7
Raj1 is offline Raj1  United Kingdom
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HI everyone, thanks for the replies,

I don't quite know the individual charecteristics of tubes one would typically see in SE amplifiers, but here goes,


Frank if you think an otl SE can sound good and getting rid of the output cap is a complex issue, then I'll go with the cap....

I'd like it to be class A biased

As quite a few of you may know I've recently built the cd enhancer II with 3a5's, there's just something so fluid and musical about the sound.

As it happens I'm now looking for simple single ended design that has undescribable fluidity, harmonic texture and 'air' (have I hust described the perfect amplifier?)

I'm very open minded (apart from the SE bit ofcourse), and upon more serious thinking an otl would help keep costs down... But I'll still consider opt's as well......


With regards to DHT's, going on what I've personally heard, yes I would prefer that the signal is amplified using these type of tubes. Compromises could be made with regards to rectifiers, which don't have to be DHT's........ Heck I'm even leaning towards SS rectification for starters and pehaps tube rec's if I don't like the sound(I hope I'm not stepping on any toes here!).

Now there's also an added twist, in the future if it is at all possible I may use this amp with active crossovers (perhaps parrallel single ended amps would be better for this????) and use my SS amp with it, ofcourse this could be a can of worms.........



Thanks

Raja
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Old 6th November 2003, 05:58 PM   #8
qwad is offline qwad  Australia
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try and find a copy of a se design published in "hi-fi world"afew years back designed for them by mr T dePARAVINCI a quite a simple design using 6080 /= 6as7g's [ both relatively easy to find and inexpensive too!!!]in the O/P with 6dj8 /ecc 88 / 6922 et all & a 12ax7 fronts I have the circuit in one of their diy supp's and could email you a copy but havent hooked up my scanner yet: errr; humph! shows how fast time flies I just dug out the supplement and it was dec /93 10 yrs ago!/ now only a whisker short of 11years.... only seems like yesterday to me: cheers and regards to all Tomcat will try and do something about that dang scanner@#**** bye, bye
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Old 6th November 2003, 09:13 PM   #9
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Raja,

Do you know how much power you need? That is determined by your speakers' efficiency, your room size, your normal listening volume, and some other factors. Once you've figured out how much power you need, then you can figure out if you can get there using SE DHTs.

I recently built an SE 2A3 amp with a design taken from the www.angela.com website (they have 2 SE 2A3 designs there, I built the one with the SRPP 6SL7 driver stage). The driver has since then been replaced with something different, the output transformers have been upgraded, and I've been trying out other things on it. So, in my experience, that is a good amp to start with, it's simple, sounds pretty good, and has plenty of room for upgrades and experiments. I think I spent about $500 for my first iteration of this amp (I think it cxan be built cheaper). So if 3.5W of power is enough for you and $500 isn't too much, this would be a good candidate.

Hope that helps.

Saurav
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Old 6th November 2003, 09:37 PM   #10
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Hi,

Quote:
and could email you a copy but havent hooked up my scanner yet:
When you do can you please send me a coy of that too?

Just use the e-mail button here to notify me.

Thank you.

Cheers,
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