Power amps for tri amp system

[coolhandjjl]

I have been tinkering with an all horn tri amp system with an active crossover. Currently, it is powered by ss amps. Almost too detailed sounding, can get fatiguing. I also play electric bass and have a few Peavey tube power amps laying around. I did a bit of re-rigging for some tests, and the information I have read here is right. Horns sound best with tube amps. The Peavey tube power amps I have may not be the best for hi-fi and they have noisy fans, but they did give me a clearly more comfortable type of sound quality.

Since I will need three stereo power amps, I need to be careful of costs. I have looked at the kits like the Dynaco clones here and at other places. Lots of nice offerings. Also, I really don't think I need to look at any SET amps as I don't listen to classical, and my source material is primarily assorted digital files. I'm guessing that I will need a 60 wpc stereo power amp or a pair of 60 w mono blocks for my bass bins, a 2~5 wpc stereo power amp for my mids, and a micro watt or possibly headphone power amp for my tweets.

Are those Yaqin or Elekit tube amps I see on ebay worth considering?

[battradio]

It would be nice to know what horns you are using . For the midrange your only going to need 3 to 10 watts , so push pull 6BQ5's will provide plenty of power , knowing if the bass speaker is really a horn would help with suggesting a amp for it .

Most of the Chinese amps scrimp on the output transformers .

[coolhandjjl]

-Bass bins are horn loaded as well. They each use two Eminence 3012LF Kappalite drivers, 4 ohms @ approx 105 dB.
-Mid is an Eliptrac 400, a kit built 2" mdf tractrix horn with a B&C DE750TN driver, 8 ohms @ approx 108 dB.
-HF is presently a Selenium HC 23-25 plastic 1" 100° x 40° exponential horn with a BMS 4552 driver, 8 ohms @ 113 dB. I'm not so sure it's the best combo for the task so I was considering replacing it with a B&C ME10 1" 90° x 60° plastic hyperbolic cosine flare horn with a B&C DE10 driver, 8 ohms @ approx 107 dB.
-Xover points at 400 and 6k via a TDM 24CX4 24 dB/oct LR type active unit.

For the bass, it seems like a pair of Dyna MKIII's or similar would be in order.

3~10 wpc sounds a bit high for the mids, the LED power meters on the SAE A201 that drives them never break 1 watt.

I also came across the Mini-Watt N3 at 3 wpc. Perhaps a pair of those to drive the mids and highs?

[battradio]

Can you build your amps yourself , or at least modify them , for the mid range and top end if you don't want single ended , 10 watt 6BQ5 amps are going to be the cheapest , and most available .And if you ever move away from the super efficient horns they will still be usable .This 12BH7 amp viewtopic.php?f=3&t=5865 would be a nice project or a push pull 6sn7 amp or build a 1626 push pull amp

[coolhandjjl]

Sure, I can build amps. What could I expect to pay for all the parts and tubes for a 10wpc 6BQ5 amp?

[battradio]

Well , that depends you could build a quad amp cheaper than two stereos .http://edcorusa.com/p/802/pm-101, http://edcorusa.com/c/86/projectpackages, http://edcorusa.com/c/67/cxppseries
and single ended would be a bit cheaper

[coolhandjjl]

A quad amp would be perfect for my needs. Didn't think there were any in the tube realm. As a newbie, how do I know if I want a SET amp or not? I do read a lot about guys trying full range drivers or two way horn systems that prefer the SET tone. For my needs, and since it already is a tri-amp system, I was thinking a regular push/pull would be sufficient.

[mesherm]

I have a question about your proposed tri-amp set up.
Since three different amps will have three different input sensitivites will your active crossover allow adjustments so you have a relatively flat response from 20 to 20K hz through the two crossover points? Seems to me you would need a microphone setup with pink noise to measure the actual speaker(s) output with the microphone at your listening location.
Also since tube amps sound best at upper bass through midrange and treble I think you could save lots of money by powering your low end base with your present solid state amp and just use the tube amps for the other two ranges. That would cut your costs significantly and still give you the tube sound your looking for.
At least you could set that up and do listening tests without the expense of two MK3s or Mk4s. If after that you still think you want tubes for the low end you can add them and you havent lost anything.

[coolhandjjl]

My crossover allows increase or decrease in each range. I have RTA software, a calibration mic, all set there.

I had thought about leaving the low frequency as solid state as you suggested. I have been trying an assortment of ss power amps that I have laying around slated for ebay. I can certainly hear the voicings of different power amps on my bass bins from thumping bass that seems to hit me with an ice pick while a different power amp renders same thumping bass with the feel of a medicine ball instead. The ss amp that seems to give me the most pleasing, warmest bass that has still has some detail is my Marantz 250M, a 125 wpc power amp (circa 1976 I believe). It's already been re-capped. That certainly will save me some bucks as a pair of Dyna MKIII's will set me back almost $1200.

So that leaves me with this 4 channel 10 wpc 6BQ5 tube power amp suggestion. I am familiar with tubes like 12xx7driver tubes, EL84 and 6L6 power tubes, but that's about it. I don't think I could build it from a schematic, but definitely could from a set of instructions or photos.

I could see a chassis with 4 RCA inputs on the rear along with 4 sets of binding posts each with a common along with a 4, 8, & 16 ohm posts. On the front, 4 attenuators. (Pots would be fine for me, don't need to be extravagent by buying stepped ones.)

So am I looking at 2 power transformers and 4 output transformers, or could it be done with one power transformer?

[battradio]

One large power transformer would be fine .Shannons boards would be good for 6BQ5's http://www.diytube.com/st35/diytubest35revc.pdf .

[mesherm]

The good part is you won't need expensive output trannies since you don't need bass.
So I'd say use two of Shannon's DIY35 boards with four Edcor XPP15-8-8K push-pull output trannies at $20.01 each and two Edcor XPWR005-120 power transformers at $43.21 each.
The Edcor OTs are 70-18K and 15 watts which is plenty for your needs. If you want less tubes you could build two Clementine 6L6 SE amps for 5 watts a channel for about the same money for the tranny iron.

[coolhandjjl]

I know this has been beaten to death in every audio forum out there, but since all I'm driving is mid and high, is a SET amp suitable for an old rock and roll guy? I can understand where people prefer SET for vocalists, stringed orchestrial music, and other mid- forward music. The SET would be easier and cheaper to build, but if it isn't right for me, I prefer to stick with PP.

So that means for a quad amp I'm looking at a chassis to hold 8- EL84's, 8- 12axx7 type tubes, 4-output trannys, and hopefully 1 really large power tranny? In the event this amp is re-purposed into a two-way driving bass and highs, I suppose 2 of the output trannys should be large enough for that duty as well, or does that complicate the build not having each channel be identical?

[battradio]

You could build two dis-similar amps on one chassis with no problems Using one large power supply .

[coolhandjjl]

So my cost savings from building a quad amp comes from one chassis and one power transformer instead of two? Every dollar helps.

[kheper]

I know this has been beaten to death in every audio forum out there, but since all I'm driving is mid and high, is a SET amp suitable for an old rock and roll guy? I can understand where people prefer SET for vocalists, stringed orchestrial music, and other mid- forward music. The SET would be easier and cheaper to build, but if it isn't right for me, I prefer to stick with PP.

SET amps are frowned on (by some people) for rock because of their limited ability to pump out bass frequencies. Since you are using an SS amp for the bass, this concern is moot.

SET amps made with big triodes such as the 845, 211, etc. - however, do not suffer from a lack of bass, because they produce in excess of 20W audio output per channel, and the outputs they use are huge, well-designed and expensive.