FR125SR + T-class questions - diyAudio
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Old 25th April 2008, 02:48 PM   #1
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Default FR125SR + T-class questions

Hello, I am about to buy/build a budget hifi system, tentatively aiming at a T-class amp (probably Charlize) with Planet10 EnABL'ed CSS FR125SR drivers. I need to ask several questions:

Q1. Is the Charlize a good match for the CSS FR125SR's?

When my accommodation situation is sorted, I anticipate living in a very small house. I will want to use one of the compact cabinet options listed here
and I may wall-mount the speakers (or even suspend them from the ceiling) to save floorspace. Sound quality will take second priority to practical living issues.

The audio source will be a media server playing FLAC files, located possibly as much as 5-7 metres cable length away from the speakers. So I'm thinking about placing the T-amp up close to the speakers, and running long interconnects. I'm even toying with the idea of using the old dual monoblock concept where I would buy two T-amps and put one directly behind each speaker. So -

Q2. Can T-amps, more specifically the Charlize, be bridged for single output to an FR125SR?
Q2a. Or can both Charlize outputs be paralleled to a single FR125SR? I expect there are impedance issues here.

Q3. With close placement of amp to speaker, what does this mean for speaker cable?
I see in the "Favorite speaker wire?" thread -
Favorite speaker wire?
that optimal speaker cable is dependent upon amp/speaker combination, and I see that single thin wires (24 AWG or so) are recommended for T-class+fullrange.
So I worry that short cable length might be counterproductive?
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Old 25th April 2008, 06:04 PM   #2
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Q1. I'd be inclined the go with the Fe127E; the CSS units need a few watts to kick some life into them -more than a low power T-amp is ideal for.

Q2. Not AFAIK.

Q3. Sure, with some care. Tie the twin inputs to a single terminal internally to make life easier. That's basically what Red Wine Audio's monoblocks are AFAIK. You won't get more power, but you will eliminate crosstalk & handle trickier loads. I'd still be inclined toward the 127 though.

Not always, wire is dependant upon the amp / speaker / situation / objectives. Roger Russell (ex head of acoustic design for McIntosh) on wire resistance: (this is assuming you don't want the wire to have an audible effect on the components it's tying together). 24AWG should be fine if your cable runs are short.

Something to keep in mind is that low level signals are in greater danger of noise issues than speaker level connections, so if you're planning on running long interconnects top tip is to use a semi-ballanced type, with individual send / return conductors & a shield, rather than the regular coax. Microphone wire is a good & inexpensive choice.
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Old 26th April 2008, 03:36 AM   #3
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Thanks Scottmoose,
So if I go with Fostex FE127E then from what I’ve seen on the forum, my options for a compact cabinet are:

Planet10’s Folded N-monopole V0.21 from the Full Range Reference Project -

Rabbitz' slightly smaller BR design -

or maybe even .25 cu ft curved cabinets from PartsExpress -

Anything else?

Yes, I had intended to go “semi-balanced” with the interconnects, using a good quality mic cable. Alternatively I saw an interesting post somewhere about old IBM Token Ring Type 9 network cable, which is 26AWG solid core, shielded twisted pair. This would seem to be ideal for long line-level runs.
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Old 26th April 2008, 05:16 AM   #4
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Instead of long interconnects or long long speaker cables, I have a long USB cable to an external USB dac. Maybe you already have a good audio card and don't want to buy something else. If you don't have an audio card that makes a serious attempt at sound quality, you'll be missing out on a lot of the capacity of the t-amp and the speakers.

Just one more option to consider!
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Old 26th April 2008, 06:16 AM   #5
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AdamThorne, you’re preaching to the converted! But thanks for making the point.
I have put a lot of time and research into high quality computer playback, mainly using advice from diyaudio forum member soundcheck. You can see our discussions here -

At this stage I’m running Linux on a low-power (& low-heat) motherboard, the Intel D201GLY2, with Chaintech AV-710 sound card. Amongst various other tweaks I have the stereo output directed to the rear channels of the sound card, which has a higher quality Wolfson DAC. The sound quality is great, but eventually I intend to use an external DAC - either via USB or ethernet (refer to peufeu’s ethernet project) but I definitely won’t be using SPDIF.
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Old 26th April 2008, 06:23 AM   #6
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Argh. I apologize in advance for my indecisiveness.
I see that FR125SR implementations can be very compact, which is a bonus for me, and given that they seem to be highly regarded maybe I should be aiming to buy an amp to suit?
Dual mono LM3875 gainclones?

Can anyone comment on FE127E + T-class versus FR125SR + Gainclone?
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Old 26th April 2008, 09:41 AM   #7
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Personally I've never liked gainclones. Can't honestly say I'm that much of a t-amp fan either, but I'd tend to go for one of those over the former. Other people have different ideas. Generally the 127 is a better regarded driver than the CSS & needs no larger (sometimes smaller) boxes. There are plenty of options available for it. Some of the better ones are here:
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Old 26th April 2008, 12:22 PM   #8
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OK, the milliFonken cabinet (for the FE127E) is perfect in size. Done.
Thanks again.

I think now that the title of this thread should have been “Compact fullrange + suitable amp questions”.
If anyone wants to add their views on good fullrange speakers+cheap amp combinations, I’m still interested to hear.
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Old 26th April 2008, 02:39 PM   #9
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hi linuxfan

I've re-read the thread in fear that I might have missed something....if you're going the FR route have you considered a firstwatt amp(sorry if I missed it)....

I have two digital systems(check my website) and I can thoroughly recommend an F2 or F4 for the fostex drivers.....I can't understand why you guys in Oz aren't all building firstwatts because conrad's heatsinks are so cheap and they are just down the road for you....

just a thought

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Old 26th April 2008, 03:52 PM   #10
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One of those, or the Zens, would be my choice too, though they can be a little more intimidating than kits / modules.
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