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In Reply to: RE: Looking for a good-value tubed integrated amp posted by tvr2500m on September 30, 2014 at 15:52:26
Hello,
Having owned MMGs, SCA-35, Citation V, etc. I can tell you right off the bat that an amp like the SCA-35 is going be wholly unsatisfactory for you. The problem lies with the fact that the Maggies aren't terribly efficient to begin with, and below 100hz, they are even less efficient. Sadly, the SCA-35 is rather puny in the bass to begin with as well, and if you attempt to EQ your way out of that situation, all of the amp's power will be sapped rather quickly.
A Citation V on the other hand has enough spare power to allow you to EQ a little more bass response out of the MMGs, and will sound very good. You won't get very high SPLs, but you will achieve decent listening levels with ample headroom. The CIT V is a good match for the MMGs. The Citation II is an even better match, and can really drive the MMGs well, even with added bass EQ. To my ears, the more correct sounding amps like Citation II & V are an excellent match to the revealing nature of the MMGs.
The MMGs are a pretty challenging load for most amps, but the HKs are a really good starting point.
My favorite 7189 (higher voltage 6BQ5) amp is the Sherwood S-5000. This amp will put out almost 25W RMS. The SCA-35 is barely 17 watts. I find the Sherwood S-5000 to be insufficient to drive the MMGs, so a SCA-35 is just going to be low SPL misery. Even my ST-70 was a bit weak for the MMGs.
You should really be looking at amps 50WPC and up.
Follow Ups:
Thanks for your note on this. I get it. This is as little power as I've considered ever. I'm keen now, though, to get small. I've found that about 75wpc, give or take a few watts, has been plenty ample to drive all the speakers I've ever owned.
Most of the speakers I own now have a sensitivity just over 90 dB. 25-35 wpc would just do the job. I mention the MMGs because I've also owned them, very much enjoyed them, and would consider getting another pair.
I was hoping for a smaller'ish integrated, ranging from 25-60'ish wpc. Don't have to sell me on the H-K Cit V and II. Great stuff. And I've got a nice C-J PV-12A preamp and updated MV-75 amp right now. This kit does the job, but I was hoping to shrink the footprint - without, of course, sacrificing quality. Could be a bit of a challenge.
- SJ
Hi again,
Ok, so you're not married to the MMGs... Well there are lots of nice smaller integrated amps to consider. My personal favorite is the Sherwood S-5000. It won't drive an MMG well at all, but for speakers 89db and up, it's fine. There's a lot to like about this amp - it's small, powerful for a 7189 pair (24W) and has an excellent preamp section with sensible, usable tone curves. The phono section is fantastic, especially if the amp still has the original Telefunken 12AX7s in it. Never tried it with moving coils, but with moving magnets from Grado to Stanton, I have been very satisfied with its performance. A selectable rumble filter takes subsonics out of warped records very nicely.
Downsides are the use of 7199s, and the higher plate voltage which makes standard 6BQ5/EL84 a bit of a gamble, and some versions can sometimes present with LF resonances in the power supply.
The earlier versions are best, they are slightly longer and have a slanted pre-amp section as opposed to the later version where the preamp tubes were under a square cover.
The Scott 299 is a good 6BQ5 amp, and looks really awesome, though I've never found one that sounded as good as the Sherwood S-5000, which has more power, better bass control, and better tone controls.
The SCA-35 is not one of my favorite amps at all. I find its sound to be a bit anemic, and the size of the output iron doesn't leave much mystery as to why. An upgraded ST-70, although not integrated, is a much better sounding and performing amplifier.
Now that new production 7591s are available, there are other Sherwood integrateds that I have always regarded as promising, although I largely divested myself of them back in the late 90's when 7591s were impossible to find. There are also some Sherwood integrated receivers that use 7868s, and have very excellent tuners (check if the multiplex unit is in there first!)
Fisher 500C is a great receiver provided it has been properly restored.
If you go the S-5000 route, drop me a line. Since it is my favorite amp, I have worked on a lot of them and know about some gotchas, tricks, and mistakes found in the schematics.
The S-5000 will actually drive MMGs if you restore them properly..The biggest gain in the S-5000 is unquestionably a 35uf film cap and the improved ground scheme..Just that alone with a basic 2.5 time increase in capacitance really makes the amp's stability improve a lot.
Honest amplification is better than excessive 2nd order distortion anytime.
"The S-5000 will actually drive MMGs if you restore them properly..The biggest gain in the S-5000 is unquestionably a 35uf film cap and the improved ground scheme..Just that alone with a basic 2.5 time increase in capacitance really makes the amp's stability improve a lot."
I suppose it's all a matter of taste. Being a bassist, I really don't like bass shy arrangements, and MMGs with an S-5000 just didn't have the dynamic headroom that I prefer. Of course this is a matter of taste, source material, etc...
Maybe this thread isn't the place, but I'd really like to hear more about your power supply mods on this amp. I too have noticed that the ground situation is a little odd on this amp; the bias supply has a floating ground on some versions, while on the earlier versions, the transformer had a center-tap on the bias winding. Where in the HV+ supply did you place the extra 35uf? I assume at the stage following the first current limit resistor?
Cheers!
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