Which Pass amp combo for active Altec system

Status
Not open for further replies.
Jump to Latest
A

anilva

Member
Joined 2004
#1
Hi,

I have an active mini-Dsp based Altec setup. The LF is Altec 515b in a Petite Onken cabinet and the HF is Altec 288g driver mounted to a Azura horn.

I have 2 units of F5 turbo, 1 unit of Aleph J and 2 units of F6 amps. I am unable to arrive at a good combination of which Pass amp to use for LF and HF in a active setup. Please advice.

People may say, that best way is to connect, listen and make a judgment using different combos. I did, but I am unable to come to a conclusion. I am too confused.

Please advice.

Cheers
 
#5
Ok Ok...guys. Let me give little insight into my dilemma.

While I like the sound of F6 and Aleph J, there is bit of cone movement at startup and shutdown (particularly Aleph) on these amps. I am bit apprehensive if they will damage the HF units because of this transient. Or may be I use a cap at the input of the HF to prevent DC.

Currently I am using the F5 variants and I am not happy with the detail particularly on the HF.

Thanks for all the raps on my knuckles.

Cheers
 
#6
There is no movement or sound with my F6 on either startup or shutdown. The dc offset is adjustable on the F6 with the pots. My Aleph 30 build did have some shutdown pop but not excessive. This is with sensitive horns. Check your dc offset on your F6 and zero them. I checked my bias like 30 days after build and it was much lower than when I set it up. I raised the bias and zero'd the dc offset again. I believe the F6 will deliver what you are seeking. My other 2 Pass builds have a wonderful sound but the F6 takes it to another level in detail and clarity and soundstage. I would be happy with any one of them if necessary with the F6 being my favorite.
 
Last edited:
#7
wdecho said:
There is no movement or sound with my F6 on either startup or shutdown. The dc offset is adjustable on the F6 with the pots. My Aleph 30 build did have some shutdown pop but not excessive. This is with sensitive horns. Check your dc offset on your F6 and zero them. I checked my bias like 30 days after build and it was much lower than when I set it up. I raised the bias and zero'd the dc offset again. I believe the F6 will deliver what you are seeking. My other 2 Pass builds have a wonderful sound but the F6 takes it to another level in detail and clarity and soundstage. I would be happy with any one of them if necessary with the F6 being my favorite.
Click to expand...

I have two F6 builds. One of the units has a problem with one channel in terms of initial oscillations and settles down after the bias builds up. I have not been able to solve that problem. I know you have tried giving me some help in another post on this issue. The other unit has no such problem. The offsets test are well adjusted and have no problems on that count.

Cheers.
 
#10
You should start by finding the gain of all your amps and the sensitivity of your drivers.
Question is- will your choices be a good pairing to be controllable?

I know the F5T v2 is 22 db. The F5T v3 should be the same. Check to be sure.
MOSFET F6 is 14 db.
Aleph J is 20 db.

Find out how much attenuation the mini dsp provides.

As for the sound quality preference of the individual amps, it's up to you.

I'd use a aleph j on the top end only, but nothing is written in stone. Altec drivers are known to be efficient, so it might not be an issue.
 
#12
vdi_nenna said:
You should start by finding the gain of all your amps and the sensitivity of your drivers.
Question is- will your choices be a good pairing to be controllable?

I know the F5T v2 is 22 db. The F5T v3 should be the same. Check to be sure.
MOSFET F6 is 14 db.
Aleph J is 20 db.

Find out how much attenuation the mini dsp provides.

As for the sound quality preference of the individual amps, it's up to you.

I'd use a aleph j on the top end only, but nothing is written in stone. Altec drivers are known to be efficient, so it might not be an issue.
Click to expand...

Gain is never an issue as my chain is front-ended by a B1 or a BA3FE and then goes to Mini DSP and from there to the amps.

The Altec 288 are very resolving and need to a high definition amp to match. Did not take a chance of connecting the Aleph J for the fear of knocking out the diaphragms during startup.

Regards
 
#14
anilva said:
Gain is never an issue as my chain is front-ended by a B1 or a BA3FE and then goes to Mini DSP and from there to the amps.

The Altec 288 are very resolving and need to a high definition amp to match. Did not take a chance of connecting the Aleph J for the fear of knocking out the diaphragms during startup.

Regards
Click to expand...

I assume minidsp is active crossover.
Just throw a 10uF polypropylene cap in series with compression driver to protect it from dc.
Or whats wrong with passive high pass filter and active low pass filter. That is what I found works best for my ears.
Or maybe a set of F4s driven by BA3 preamp. Lots of fun ways to use F4s for your application. Read the F4 user manual.
 
Last edited:
#16
Tweeters need series capacitors to block DC. Rule of thumb is the resulting cap/tweeter high pass -3dB should be two octaves below their crossover frequency, which is f=1/(2pi*R*C), R being the tweeter impedance at the crossover frequency.

As already mentioned above, SPL levels need matching, especially with different amplifier gains. Time alignment is also a concern. Do you have a setup to measure (in-room) frequency response?
 
#20
anilva said:
I used a Behringer digital crossover before I moved to miniDSP, and I found miniDSP way better than the expensive Behringer, in terms of sound quality as well as noise.
Click to expand...

Very nice.
How much is minidsp?

The way I use Behringer is digital in and digital out all via XLR AES/EBU. It then goes to a decent external DAC then to Firstwatt B5. It seems to work very well when setup like that.
I'm trying to simplify everything though. I prefer the less is more philosophy.
 
Last edited:
Status
Not open for further replies.
Top Bottom