Amplifier advice from Ohm Walsh 100 Mk. II owners

What are the power, input impedance, current delivery and damping specs on the Sumo and Hafler amps?

Most any amp will drive them if used in the correct matching size room (see OHM web site for model to room size mappings).

To drive and CONTROL them to their max however (can be a BIG difference in results) in a properly matched room, I'd recommend a beefy 80 w/ch or higher amp with good current delivery capability and damping factor of 50 or higher to be safe.

Similar for larger Walshes but for those I would throw as much power and current with high damping as is possible at them. Class D amps are an excellent choice to accomplish this with reasonable cost of ownership these days.

Because the OHm Walshes have ben reasonably affordable over the years, a lot of people (including myself) have made the mistake of running them of similarly affordable receivers or integrateds that work OK but are not able to drive and control them to the max, which is needed to get the results that might be considered competitive soundwise with many of the "big boy" higher end systems out there.

Hi Mapman

Thanks for chiming in. Here are the specs of the Sumo Nine from the manual I was able to find.

Class A amplifier

Power Output (both channels driven 20Hz to 20KHz):

8 Ohms: 60W @ less than 0.25% THD
4 Ohms: 120W @ less than 1% THD

Input Impedance: 1 megohm

Damping Factor: 120 min, 20Hz to 1 KHz

I don't know how to calculate current delivery but the manual of the Sumo Nine can be found here.

http://www.davidsaudio.com/nine_plus_manual.doc

The specs of the Hafler DH-220 can be found on page 16 here.

http://www.hafler.com/techsupport/pdf/DH-220_amp_man.pdf

I pulled some specs that I'm hoping will help you.

Power Rating: Less than 0.02% total harmonic distortion at
any power level up to 115 watts continuous average power
per channel into 8 ohms at any frequency between 20 Hz
and 20 kHz with both channels driven.

Input Impedance: 47,OOO ohms.

Input Sensitivity: 1.55 volts rms for 1 15 watts into 8 ohms.

IM Distortion (SMPTE): Less than O.OOS’%, from 1 watt to 1 15 Damping Factor: 300 to 1 kHz into 8 ohms
watts into 8 ohms. 60 to 10 kHz into 8 ohms

Typical THD at 115 watts into 8 ohms: 1 kHz - 0 0025%; 1O kHz - 0.007%; 20 kHz - 0.012’/‘

Frequency Response into 8 ohms: - 3 dB. 2 Hz to 160 kHz at 1 watt, +O, -0.5 dB, 6 Hz to 60 kHz at 1 15 watts

Rise Time: 10 kHz. 60 volts peak to peak square wave, 1 0% to 9 0 % 2.5 us.

Slew Rate: 10 kHz. 60 volts peak to peak square wave: 30 VI’,~ s.

Typical Channel Separation: 20 Hz:> 75 dB
1 kHz:>85 dB
20 kHz: >6S dB

Signal to Noise Ratio, unweighted: Better than 100 dB at 115 watts into 8 ohms.

I'm hoping either amp works with the Ohm Walsh Micro Talls or the 100 series. I can't fit the larger Ohm Walsh series speakers in the listening space I have to work with.

I also like these amps a lot. I really don't want to sell them in favor of Class D amps. The ones in my budget that I've listened to weren't for me sound wise.

I think either amp should work well with either MicroWalsh or 100. I'd try each and see and then go from there if needed.

Again, make sure these are the right size for your room based on the model to room size mappings on the OHM site. 100s will do better in a larger room than Micros.

In teh case where the OHM Walshes are undersized for the room, even in the case of Micro Walshes, adding and integrating a good subwoofer later if needed is a good way to make up the difference in lieu of going to a larer model.

Also, some report good results using even tube amps with the OHM Walshes when subs are used to offload the work needed for the low end. So adding a sub and offloading the work for teh low end to it is another option for weaning better performance out of any given amp.

Mapman, any sub recommendations to go with the 100s?

HAven't tried subs with 100s (no need in my 12X12 rooms that I use them in).

Choice of sub will also probably largely depend on room size.

Bigger room-> bigger sub with more power needed. That usually always is the case.

The line I am most familiar and comfortable with from having heard sound good in higher end dealer systems in general is Rel. That is a popular line with the audiophile crowd in general. I am sure there are many other good ones though.

In general, 2 subs are usually better than 1, but 1 can work well especially if big enough and you have flexibility with locationand used with more full range speakers to start (like the 100s) where the crossover frequency need not be too high. Higher frequencies are more directional sounding in nature so a lower crossover point is generally better especially if using just one sub.

Personally, I would rather right size the OHMs to the room if possible rather than go the sub route, but that is just me. You might defer some cost adding a sub later, but not really save much if any money in the end once you do.

Plus the Walsh drivers are full range up to about 7Khz or so, which is part of its magic in terms of coherency. Crossing over to a sub might intrude on that.