I have just fitted and tested three of these. The amplifiers are identical HH S-500D models. The specs for these amps are as follows;
210W rms @ 8ohm
340W rms @ 4ohm
500W rms @ 2.5 ohm
The power rails are 63volt supplying 6 NPN output transistors per Channel. 2x15,000uF Caps. 1KW toroidal transformer.
A friend who knows how to work out the mathematics for the Outputs has informed me that fitting the K4700 modules to these amps is a waste of time because the Vellman relays will not cope with the current or power the O/Ps will deliver if they go DC.
Have I wasted my time and money on these or is it possible to fit Relays of a higher rating or something?
Any help would be much appreciated.
PS. The speakers I am trying to protect from DC output are at best very expensive to replace and at worst not available from the manufacturers anymore.
Should work fine, however, you can fit ‘better’ relays if desired.
Just make sure that they are 12V types and make sure their power consumption is more or less equal (40-50mA).
[quote=“VEL417”]Should work fine, however, you can fit ‘better’ relays if desired.
Just make sure that they are 12V types and make sure their power consumption is more or less equal (40-50mA).[/quote]
Huge thanks for rapid reply. As always there are some complications I avoided in first post.
I use one of the four HH amps for my home Hi-Fi into very high efficiency speakers, (Electrovoice Sentry III) 20Watts=deafening, 50Watts=police/arrest etc. So mostly 10W ClassA stage of A/B amp.
However,
These four amps also double up for sound rig work for Dance, House, Techno, Funk and Hip Hop etc. along with two C-Audio 707 amps. When the HH are doing Pro work I have to run them in Bridge mode, 900W @ 5(ohm) rms capability but actual run condition is something closer to 700W rms into 6R (8ohm nominal impedance).
My ‘basic’ understanding of the situatioin is that in ‘bridge’ mode, one channel of a stereo amp is doing the ‘push’ and the other is doing the ‘pull’. Therefore I presume the 6 output transistors of each channel are running through each relay whereas in Stereo mode maybe only 3 of the 6 are if the amp goes DC. When the ‘mess’ hits the fan in these things I really do not know what happens.
I have read comments about these amps such as ‘‘only press the ON switch with a BROOM HANDLE’’ etc., probably because of the in-rush current (1KW transformer). Very worrying!!!
The Velleman relays seem to be rated @10A 28VDC, or 15A 125VAC. I am guessing that the DC rating is the most relevant one since that is the current the relay will be coping with if the amp goes ‘DC’.
If the Velleman relays are likely to ‘weld’, maintaining the circuit to the speakers, when the amp is in bridge mode and a fault occurs, what would constitute an up-grade of the relays? What should the numbers say on a replacement Relay?
I really hope the standard relays are up to the job and my ‘knowledgeable’ person is confusing in-rush with output.
We’d recommend relays suited for air-conditioning compressors.
They feature high peak-current handling and protection against ‘welding’.
Sorry, no figures, brands or types. We have no hands-on experience with this matter.
Please Google or check with your distributor.
[quote=“VEL417”]We’d recommend relays suited for air-conditioning compressors.
They feature high peak-current handling and protection against ‘welding’.
Sorry, no figures, brands or types. We have no hands-on experience with this matter.
Please Google or check with your distributor.[/quote]
Thanks for advice. What I see of these relays are all far too big to fit on the Velleman board let alone in the free space that remains inside the amps. The cost, @ 40 to 65 US Dollars each is also prohibitive. I will have to look further into alternatives and take the risk on the existing relays for now.
Your advice though is much appreciated here.