embarking on a (epic) single driver valve amp journey

[GeorgeO]

Consider going through the Maqnequest forum. Magnequest is presently among the best transformer mfrs around, and Mike Le Fevre who owns is is very encouraging of diy.

Their SETH amp design is in the public domain and there is a detailed step by step manual available for download. They sell their output transformers, and often have special deals Their supply OEM transformers to some of the best names in the business like Wavelength. Wright Sound, Fi etc.

Another site to check is the Bottlehead site.Their small SET amp kits are also well acclaimed and their forum has a lot of interesting posts.

 

[gobble]

I've used fibre stuffing for damping. I suspect this reduces the effective efficiency of the speaker. Not sure though

Oh I thought you were talking about damping factor. The Fostex enclosure design document says bass reflex type will sound over-damped. which damping are they talking about?

Thanks.

 

[jai1611]

The Fostex enclosure design document says bass reflex type will sound over-damped. which damping are they talking about?

Thanks.

probably the bass response falloff, which is much more in the basic bookshelf design than the larger stand integrated bookshelf or the many tower designs

 

[gobble]

probably the bass response falloff, which is much more in the basic bookshelf design than the larger stand integrated bookshelf or the many tower designs

You mean low freq falls off steeply right? I never heard the word damped being used to describe frequency roll-off and taper. Hence the confusion on my part. The bass reflex for 166e is the tall narrow style.

Regards

 

[jai1611]

You mean low freq falls off steeply right? I never heard the word damped being used to describe frequency roll-off and taper. Hence the confusion on my part. The bass reflex for 166e is the tall narrow style.

Regards

Even I'm not too sure what they mean.

If making a tower, there are some pretty interesting horn and transmission line designs out there. My problem was that I specifically wanted a bookshelf. also, since this was my first build, wanted to keep the design simple.

 

[suri]

grin, didn't know i'd have that effect on you! good luck! but you might as well do it right.

if you want the best of a single driver, get a good fostex driver like george has done. its the same driver that my speaker has. that project is a good one to explore.

the other part is the tube amp. el34s and a push pull (looked like it) are way way off the mark as far as my opinion goes. choose a direct heated triode. you'd need to research tube qualities before choosing the amp. most people assume ok lets get into tubes and then jump into the first tube amp that seems to reviewed well. and then they're surprised they dont like the sound. more than SET or push pull, the tube itself makes the biggest difference in sound. so please please please start at the right point - the tube

popular choices for SET amps are: 845, 2A3, 45, 300B. the 845 is powerful and big sounding, the 2A3 delicate sounding and intimate, the 45 is very honest and extremely 'there', the 300B is a lush sounding tube that does bass not as well as an 845, a 2A3 or a 45. so as example if you get a 300B SET amp and complain about bass that's not tight you quite obviously have not done your requisite homework! you have SET amps based on other tubes like the el34 but that's taking something that's not right for the task and trying to force it to do something it was not intended to do.

my suggestion suri, get the 2A3 amp from viren and experiment with a 45 tube bought off ebay. that ought to give you a true taste of single driver SET sound.

liking it is another matter altogether and depends on how well you've done your homework on reading up on the qualities of the combo and what is required, being comfortable with giving up certain qualities in order to gain certain ones. judging by your amp choice, you haven't quite done your homework yet so be prepared to be disappointed

regards

Hi stevieboy,

i know zilch about valve amps, so i will have to start reading, researching and generally get myself nudged in the right direction! i suspect it will be a long process, because i do not know too much about the behaviour of full-range drivers either. :sad:

 

[suri]

IMO, you can't go wrong with DECWARE amps. They are relatively cheap too. Sound is BRILLIANT. I heard these for just 5 minutes in a tiny shop - couldn't see what speakers they were paired with - The amp. stuck with me because I specifically asked the guy at the counter what amp. he was playing. I had a train to catch so I had to rush. The next time I visited [after a year] the shop was gone.
I checked the DECWARE site - they have the SE84C which is the cheapest and I heard the SE84B [I think - and I'm 99% sure the shop guy said a B and not an A or a C]. They also have DIY kits for that amp. if you are so inclined.

thanks, will research!

 

[GeorgeO]

So what's your opinion about DHT-PP?

Personally I think EL 34 pp are an excellent choice if you have multiple amps-I love their sound as well. They are an ideal choice for driving speakers that need grunt which a lot of speakers need. My Joplin 2A3 DHT-PP is also very nice but different, when compared to my EL 34 PP. Class A has a different sound when compared to Class B when paired with speakers that are efficient. In a way debating about amps is like debating about different speakers..

YMMV



George


>The other part is the tube amp. el34s and a push pull (looked like it) are >way way off the mark as far as my opinion goes. choose a direct heated >triode. you'd need to research tube qualities before choosing the amp. most >people assume ok lets get into tubes and then jump into the first tube amp >that seems to reviewed well. and then they're surprised they dont like the >sound. more than SET or push pull, the tube itself makes the biggest >difference in sound. so please please please start at the right point - the >tube

 

[GeorgeO]

Joplin: http://www.diyhifisupply.com/files/david-joplin-2a3.pdf

 

[stevieboy]

So what's your opinion about DHT-PP?

Personally I think EL 34 pp are an excellent choice if you have multiple amps-I love their sound as well. They are an ideal choice for driving speakers that need grunt which a lot of speakers need. My Joplin 2A3 DHT-PP is also very nice but different, when compared to my EL 34 PP. Class A has a different sound when compared to Class B when paired with speakers that are efficient. In a way debating about amps is like debating about different speakers..

YMMV



George


>The other part is the tube amp. el34s and a push pull (looked like it) are >way way off the mark as far as my opinion goes. choose a direct heated >triode. you'd need to research tube qualities before choosing the amp. most >people assume ok lets get into tubes and then jump into the first tube amp >that seems to reviewed well. and then they're surprised they dont like the >sound. more than SET or push pull, the tube itself makes the biggest >difference in sound. so please please please start at the right point - the >tube

hi george,

am presuming the question was targetted at me? well, i've never heard a dht push pull amp, only the regular el34, kt88 type push pulls. but am guessing they give up a bit of pureness for power?

the recommendation to go for SET was cos with single drivers would be a better pairing since i think suri was aiming for that pure sound of single driver SET combo i apparently planted in his mind .

regards

 

[GeorgeO]

I forgot who I posed the question to, actually, spend some time scrolling back and forth, but cant figure out who I asked

DHT PP is a different animal than regular PP. That's the reason why I posted the Joplin link. The ustaads who mfr it have given a detailed writeup - much more than I could!

What I observe with DHT-PP(Class A for starters), is that it doesnt run as hot as regular pp-even though regular pp is Class AB most of the time.

Second, is that while detail is good , it doesnt have the punch that say KT-88s have, or to a leser degree my EL 34s have. However it is essential, probably like SET, to have speakers that match.

I find that with high sensitivity speakers, I enjoy small jazz groups and female vocals a lot more, whereas for rock I may prefer a punchier amp mated to another speaker. I also have 2 way monitors which can run off the same amp that I am now using for the FR. That system is very comfortable with the Joplin, but being a stand mounted monitor needs a sub to augment bass. By and large all of my listening is done at fairly low volumes.

George

 

[stevieboy]

george,

i actually have heard a dht in push pull and SET. the cadence 845 and siva's 845 SET. there's an interesting story to it. when i first heard siva's SET 845 i thought it sounded better than the cadence and put it down to better build. at this point of time i did not know it was SET cos it had two tubes per channel and i jumped to the conclusion it was a push pull one. somehow at that time siva too did not mention it was a SET and for some months i went under this impression. then square wave posted that it was a SET and i said hey no i think its push pull do check. that's when i discovered it was a SET amp. so somehow i ended up preferring the SET version of course two different designers but there it is, 845 tubes push pull and SET if anyone wants to go listen.

regards