tri-amp advice

[mitchba]

Hello, a few years back this forum assisted in troubleshooting my build of a Pass A40:
http://www.diyaudio.com/forums/pass-labs/166784-pictures-your-diy-pass-amplifier-81.html#post2644271

Since then, I upgraded the power supply capacitance to a total of 264,000 uf . I really enjoy the sound of this amp.

I use Acourate for loudspeaker and room correction. Acourate also has capability for digital XO which I wish to pursue next.

The speakers I use are similar to Klipsch Cornwall’s, except with updated components from Bob Crites. 15” woofer, mid is a Selenium D405 compression driver mated to a M2380 horn, and treble is BMS 4540 to HM-11 horn. I listen mostly to rock and blues, especially live recordings.

I am hoping to receive more good advice as to which 2 Nelson Pass amps to build next. I assume for the mid and treble horns, and run the Pass A40 on the woofers. However, I default to the excellent experience in this forum to suggest the best approach.

Thanks in advance!

Mitch

 

[AudioSan]

i would have used the A40 for mids. and F5 turbo on woofers. and maybe a aleph mini for the tweeters. or maybe a aleph J.
or F5's all the way. you can re-use the A40 PSU for a F5 turbo V1/V2.

 

[mitchba]

Thanks AudioSan for your advice. Your thoughts for the A40 on the mids? The woofer is 4 ohms and the mid/tweeter compression drivers are 8 ohms. I don't know if makes a difference on choice of amp for woofer? Lot's to choose from. Is one amp easier to build than the others?

 

[AudioSan]

push-pull class A(F5) will give you more punsh and power in 4ohm then a SE class A(aleph/A40) the A40 is a realy great amp for mids. F5/F5 turbo(without diodes) is the easier type of amps to build. (custom to your needs)

 

[mitchba]

AudioSan, thanks again for your advice. One last scenario, I came across the amazing Amp Camp Kit - Kits Given my mids and tweets are compression drivers/horns with ~110dB sensitivity, these amps seem to be enough power and thread comments suggest good sound... Thoughts?

 

[AudioSan]

i have never tried that amp. so i can't say anything about the sound.

 

[AndrewT]

With 110dB/W @ 1m speakers you could get away with using a headphone amplifier designed to suit low impedance.
Something like 5W is going to satisfy most listeners in normal domestic listening.

 

[mitchba]

AudioSan and AndrewT, thanks!

Anyone comment on the sound quality of the Amp Camp Amps driving high sensitivity mid and treble horns?

 

[Eric]

Hi Mitch,

I am very impressed by the ACA driving my set of 2-way 4-ohm bookshelf speakers (Tony Gee's HATT) as well as a pair of Mark Audio CHR-70 drivers (8-ohms) in a 1/4cu ft vented box from Parts Express! Plenty of bass, clear mids and highs. These aren't high efficiency, though, so they don't really match your criteria. I would think the ACA is a good match to high efficiency drivers.

The ACA was not at all happy driving my big Avro 4-ohm speakers - these are about 87dB efficiency and really sing with my a40 and Aleph-X amps. But, with the ACA, the overall sound was congested, bass was poor, midrange and treble were not as smooth - just general unhappiness here...

 

[mitchba]

Hi Eric, thanks for your reply!

Maybe I am missing something. My plan was to triamp my speakers. The 15" woofer is a high efficiency 4 ohm driver. I was going to put the Pass A40 on those - meaning the output terminals on the amp directly connected to the woofer (no passive xover).

I was thinking of directly connecting a mono ACA on my mid horn that is ~110 dB SPL 1w @ 1m sensitivity. And another mono ACA on the tweeter horn that is 115 dB SPL 1w @ 1m sensitivity.

The digital crossover would put everything below 500 Hz through the A40 to the woofer, 500 Hz to 5 kHz to the mid horn and 5 kHz and above to the horn tweeter using the ACA's.

The ACA's would be driving (direct connection) high efficiency 8 ohm horns that are bandwidth limited, due to digital XO. I thought the ACA's would easily drive the horns? But not sure what the sound quality would be like?

Thanks, Mitch

 

[PKI]

Not sure about that part with no XO for your woofer. Look at its response, see all these nasty stuff before high freq roll off (applicable to almost all woofer I've seen) -- this will be harshness in your music there.

 

[mitchba]

The digital XO will feed 500 Hz and below to the A40 connected to the woofer. Maybe I misunderstand?

 

[Eric]

My thinking is that the ACA is well-suited to high efficiency drivers, especially mids and highs. I'm not sure that it would be my first choice for woofer duty, but it might be interesting to try. Given that all of your drivers are so efficient, it might be quick and cheap to tri-amp using the ACA all the way...

Then swap out an ACA for an F5 or a40 (both are push/pull designs) for the woofer or mids. See what you think of the difference. AudioSan had an interesting idea for Aleph-mini or Aleph-J for tweeters...

All kinds of fun possibilities. When I first started, I was interested in picking one design and building it for a specific purpose. Nearly a decade later, I'm more open to the "build it and give it a try" approach. Then build something else for fun and see which one you like better. Different amps mate differently with different drivers. I can't decide on which speakers to build next as there are several that look interesting. I think I'll build one design and listen to it for a year or so and then build something else to see how they differ...

 

[mitchba]

Eric, thanks, I like your approach! I think I will start with the ACA's on the mids and tweets. I also like what AudioSan has suggested and will build those over time as well. Cheers!

 

[PKI]

OH, sorry, your words: "meaning the output terminals on the amp directly connected to the woofer" mislead me, did not see no PASSIVE XO first. From what I found with recent experiments with my OB designs: 15" woofer better be crossed at around 150-200Hz and F5c with 2 pairs of outputs did a good job of driving 2x alpha 15. However, it is all about your definition of loud

 

[AudioSan]

A40 for mids.
F5 turbo for lows.
aleph JJ mini for tweeters that must be nirvana

 

[mitchba]

PKI, my bad wording... The woofer is a custom design by Bob Crites I linked above as a high efficiency replacement woofer in Klipsch designs (Khorn, Cornwall, etc.) and supposed to make it up there. But will see with the digital XO.

AudioSan, I am excited to build these! I am going to start with the ACA's and see if my 10 year old daughter can put them together. Learn from the sound while I build the other amps. Besides, I can't resist those red chassis!

 

[PKI]

And if I may ask: why do you need tri-amping? Not bi-amping or even a single amping?

 

[DougL]

And if I may ask: why do you need tri-amping? Not bi-amping or even a single amping?

Having an amp per driver without a passive crossover has advantages.
It's especially interesting with low power class A amps.

All it takes is 6 channels of amplification, a digital or analog crossover.

Give it a try.

Doug

 

[AudioSan]

PKI, my bad wording... The woofer is a custom design by Bob Crites I linked above as a high efficiency replacement woofer in Klipsch designs (Khorn, Cornwall, etc.) and supposed to make it up there. But will see with the digital XO.

AudioSan, I am excited to build these! I am going to start with the ACA's and see if my 10 year old daughter can put them together. Learn from the sound while I build the other amps. Besides, I can't resist those red chassis!

yes. why not take them early