Proac 2.5 clone, what Amplifier

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Hi, I will finish my proac 2.5 clone soon, it's said that the proac is better if drive by tube amp, but how about ss?

1. is there any tube amp (or kits) under $500 will match the proac 2.5 clone well?

2. what's the minimum power output of the tube amp for this speaker(86db)? room size: 15' x 10'?

2. How about the nad and rotel amp for this speaker?

3. Or other SS amp under $1000 suitable for this speaker?

waiting for your input

b.regards
kevin
 
Hello,

A1- I'd like to know this too! :)

A2- This speaker, like many other midwoofer/tweeter 2 way speakers with full baffle step compensation, has low sensitivity.
Typically mid to low 80s.

The commercial Response 2.5 was measured by Stereophile magazine as 83dB/W at 1m.

Amplifier power really depends on how loud you want to listen, but as a general rule- too much is never enough. ;)
Generally, the following rules of thumb may be helpful:

In-room speaker sensitivity: + ~4dB
Stereo speakers: + 3dB
Listening distance: -6dB per double distance
Amplifier power: 10 fold gives 10dB gain eg. 10W gives 10dB gain, 100W gives 20dB gain.
2 fold power increase gives 3dB gain, so 4 fold- 6dB, 8 fold- 9dB.

eg.
ProAc Response 2.5 sensitivity (anechoic) : 83dB/W/m
in room sensitivity : 87dB/W/m
2 speakers (stereo): 90dB/W/m
listen at 2 metres : 84dB/W at 2m
10W amplifier : 94dB at 2m
20-40W amplifier : 96-99dB at 2m
100W amplifier : 104dB at 2m.
100W amplifier : 98dB at 4m.

ref:
http://www.axiomaudio.com/archives/power.html

A3. I had a NAD C320 (40wpc) paired with the clones, but sold it as soon as I found something better. It's overly warm and lacks detail. The higher power NAD may be better, but I have no tried any.

A4. I have a DIY Rod Elliot P3A. You can build it as 60wpc (8 ohms) and I believe it will be suitable for small rooms. Sitting at 1-3 metres you will never each live concert-like (90dB sustained, and 110dB peaks without significant compression) levels with the ProAc clones, but it will be loud enough to be enjoyable.
 
If your budget is $1000 it leaves quite a few amp options, specially 2nd hand. I am not up to speed with the latest mid-fi SS options but since you are int he US on ebay there are often Sumo Nine power amps 70W class A (like right now there is a beauty), old NAD 2030i is great also. I recently tried a Plinius SA100 is didn't like the clone or the other way round. But why not stop beating around the bush or take years to realise, just go for a 2nd hand tube amp of at least 30W using EL34 tubes (realible and cheap to replace tubes), or better still any KT88 tube 50W type amp. They often come as integrated or with pre amps. I think Cayin from China make excellent value amps. Also, old Acousitc Research tube amps. With tubes you need to find out how to maintain them or at least have a technician who can service them once or twice in a few years. You will never look at SS amps, with a few exceptions like some of the ice module amps.
 
I have used the following with my clones;

Rotel 1050 = Clean sound but a little weak
Adcom 545 = Clean sound but a little weak
Denon 3803 HT Reciever - Clean sound but a little weak
Adcom 565 mono blocks - not so clean but has the dynamics I was looking for
Mccormack DNA-1 = Bliss :)

I also would like to try tubes but have yet had a chance to do so.....

Due to there low sen. give them some good SS power and you will be fine..........
 
I have used these amps and listed them in order of preference. My Audio buddies and I have used the 2.5's for years before one moved up to the 3.8's. Mine are clones, they have the real thing. Yes, the clones are as good or better than the "real" ones.

VAC Ren 70/70
VAC Ren 30/30
Audio Research VT-100
Pass Aleph 5
Quicksilver M135
Musical Reference RM-200
Sonic Frontiers Power 2
Quicksilver 8417
EICO HF-89 tweaked
BAT VK60
Audio Research D100.2
MusicalDesign D150/D140
Monarchy SE-100

Obviously they are all among the better amps available.
Tubes have the subjective advantage. SS is more neutral and tubes have more flavor but with more transparancy and realism. The top three I could live with forever. I am in the process of building a 300B PP amp because of these results. I might try an Aleph 3 for a listen. This list was compiled over many years.
 
I don't know what's the phono stage in preamp, could you please tell me?

The amp is a used "IDEAL INNOVATIONS KT88 + 12AX7 TUBE AMPLIFIER" with "40WCh 8 OHM 80W 4 OHM AND TRIODE SWITCHING", I just brought it from Ebay, there is no more information and it's still on its way to me.

I prefer a used pre amp, less than $300. SS or tube preamp is better in this case?

Thanks
 
Phono means turntable compatible circuit built in, so its a good thing.

I think maybe you have bought an "Audio" Innovations amp, company which is not around anymore but made good amps from UK. Good to have choice of 40W pushpull mode and maybe 20W triode mode. How much did you pay?

Generally always use a tube preamp as SS will go backwards in sound (flat & dull like most SS amps). You should able to use as integrated if the amp has a volume knob or play through CD with volume control.

When you get the KT88 amp give it time to warm up, 30 mins + few more hours best, it may need some tuning to sound better where all the 4 valve voltages are operating similar, resulting in sharper sound. Don't expect 100% SS loudness levels, maybe 80-90% will do.

Many other SS amps tried in the past did not work so well like:

Aleph 3 - neutral sounding, lack of bass depth
Naim 250 - quite good, lack bass depth
Bryston B3? - good treble, lack bass depth
Bel canto digital - as above, better bass, no life
Sumo 9 - best SS sound match, great bass, vocals, noisy fan
NAD 3020i - 20W great bass and good mids.

Most tube amps were very good with crystal clear treble, magic vocals, great bass depth and texture, imaging.
 
Thanks for your input, I am building my proac 2.5 clone, and I really want to thank AI.M and his website!!! My MDF are cut by home depot, bad cut, 4-5 pcs MDF have 2mm difference.

Is the internal cable in the proac 2.5 clone important? 'cause I want to put the crossover on the back panel above port, the line will be short.

I think my tube amp is not from UK, I think it's built by Syd Beaumont, a custom tube amplifier company, (www.idealinnovations.biz). I paid $650 to it's second owner.

So I should look for tube preamp, is there any specs on the preamp I should look for?

One thing of the audio indurstry is that people don't believe in number, they believe in their ears, but should we create more numbers to descript the sound so that we can have more "objective" idea?
 
something to keep in mind, woofers are rated at 70watt, so whatever you decide, 100watt should be sufficient.


im using a diy p101, i have not been able to compare any other amps with these particualar speakers so i can't comemnt any further!. certainly nothing negative to say tho.


cheers
 
Ideal Innovations website amps look very nice. Perhaps you have the Classic 80 amp from their site which appears to have 2 control knobs on the front, maybe one is the volume. If not then you may need a preamp. An average good tube preamp can generally make the sound about 10% smoother and you can tailor the sound of the original power amp. If your power amp has inputs you should be able to connect them to a preamp. When looking for tube preamps perhaps go by the build quality and sound if you able to audition. I have heard some DIY tube preamps that were very good and it wasn't difficult to be happy with most of them. Check audioreviews.com for suggestions and look out on ebay, e.g. Conrad Johnson PV10? range etc.
 
Internal speaker cable length is better short but leave enough so you can pull out the drivers when tweaking the crossover. I use Axon (around $3/m) internal wiring for most of my speakers but others may recommend alternatives around your location. Monster type cabling can be dull sounding. Chose something with clear treble to compliment the tweeter and good bass, infact everything within your budget.
 
Power cable is not meant for speakers. I used Axon 2 but try any combination you think is good. For woofers I combined 3 strands of single Axon per terminal (driver connection point), that is 3-4 strands for -ve & 3-4 for +ve, but only 1 per terminal on tweeters.
 
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