A dual-channel Vari-Mu compressor with mid/sides switching used to mean spending Fairchild money: five figures, minimum. Heritage Audio's Herchild 670N changes that math at $3,000, but so do a handful of competitors sitting between $2,000 and $10,000. Before you commit a chunk of your studio budget, it's worth knowing exactly what separates these units on paper, and where the differences actually matter once you're staring at a mix bus or a mastering chain.
This guide works from the documented specs and hands-on notes in MusicTech's Herchild 670N review, plus the pricing and rack-space figures the reviewer cites for the Manley Variable Mu, Gainlab Dictator, Tegeler Vari Tube, and Heritage's own Grandchild 670/500 and Herchild 670. Treat every price and spec as a snapshot; manufacturers change pricing and feature sets without warning, so verify current numbers directly on each brand's site before you buy.
What the spec sheet tells you
The table below compiles the manufacturer-stated figures referenced in the source review. These are documented facts, not listening impressions.
| Unit | Price | Rack Space | Channel Modes | Tubes / Transformers | |---|---|---|---|---| | Heritage Audio Herchild 670N | $3,000 | 5U | IND, LINK, LAT, VERT (mid/sides) | 4 NOS 6BA6 valves; 2 custom input transformers | | Heritage Audio Herchild 670 | $10,000 | 6U | Dual-channel, Fairchild-style | 22 NOS valves; array of transformers | | Heritage Audio Grandchild 670/500 | ~$2,000 | 500-series (1 slot) | Stereo-linked | Fewer tubes/transformers than 670-series | | Manley Variable Mu | ~$5,000 | Not specified in source | Not specified in source | Not specified in source | | Gainlab The Dictator | Not specified in source | 2U | Lacks stereo-link/mid-sides, per reviewer | Not specified in source | | Tegeler Vari Tube | Not specified in source | 3U | Lacks stereo-link/mid-sides, per reviewer | Not specified in source |
A few gaps are worth flagging honestly. The review doesn't publish Manley's rack height or tube count, and it gives no exact pricing for the Dictator or Vari Tube — only that both cost "fewer dollars" than the 670N. If those numbers matter to your decision, pull them from Manley, Gainlab, and Tegeler's own product pages (source).
Why mid/sides mode is the real differentiator
The 670N offers four operating modes via its AGC dial: IND for dual-mono independent channels, LINK for equal stereo compression, and LAT/VERT for true mid/sides encoding and decoding. That last pair is the feature the reviewer keeps returning to, and it's the one the Dictator and Vari Tube reportedly lack.
Mid/sides matters for mastering because it lets you compress the center image (lead vocal, bass, kick) differently from the stereo-width elements (reverbs, background vocals, wide guitars). The reviewer's hands-on note is specific here: working in mid/sides also sidesteps left/right imbalance caused by valve-to-valve variation, since both channels pull from the same mid and sides signal rather than two separately drifting tubes. That's a subjective but plausible engineering observation from actual use, not a spec claim, and it's the kind of detail that only shows up once you're pushing gain reduction on a real mix.
If your work is stereo mastering only, and you never need to compress two unrelated mono sources independently, the mid/sides question is where the money math gets interesting. The Grandchild 670/500, at roughly $2,000 in a single 500-series slot, delivers the Fairchild-style Vari-Mu character in a stereo-linked design without the extra rack real estate. The review calls it "perfect for mixing or on-the-go mastering," but it doesn't credit the Grandchild with the same LAT/VERT mid/sides modes documented on the 670N. If true mid/sides processing is central to your mastering workflow, that's a real step down in capability, not just a smaller box. We cover related ground in davinci resolve first tab freeze: how to fix it fast.
Rack space and power supply reality
Here's where the 670N's "bargain" framing needs a gut check. At 5U, it's smaller than the full Herchild 670's 6U cabinet, but the reviewer is blunt about the real-world impact: it "still feels huge" in a compact workspace. The reviewer's own racks top out at 4U, meaning the 670N literally wouldn't fit there without a rack upgrade.
That's not a minor footnote if you're working in a home studio with a single 12U or 16U rack case. The unit also requires an external power supply, adding another cable and another surface to find room for — something the Gainlab Dictator (2U) and Tegeler Vari Tube (3U) avoid by comparison, at least in raw rack footprint.
If floor and rack space are tight, weigh that 2-3U difference against the mid/sides features you'd be giving up. The Grandchild 670/500 sidesteps the rack-space question entirely by living in a 500-series chassis — the more compact path if you already own a lunchbox and don't need the 670N's dual-mono tracking flexibility. This pairs well with our guide to how to produce psychedelic trip music: a producer's guide.
Price versus feature tier: where the 670N actually sits
According to the review, the Manley Variable Mu costs about $2,000 more than the 670N, putting it around $5,000. The Herchild 670 above it sits at $10,000 — over three times the 670N's price — for what the review describes as a similar sonic ballpark achieved with far more tubes and transformers. The 670N reportedly closes most of that sonic gap using fewer components, while adding a feature the full-price 670 doesn't have: per-channel make-up gain control.
That pricing structure is the crux of the reviewer's verdict. The 670N undercuts the Manley by roughly $2,000 while matching or exceeding it on stereo-linking flexibility and mid/sides smarts, and it undercuts the flagship Herchild 670 by two-thirds while landing close to it in character. The Dictator and Vari Tube cost less and take up less rack space, but the review states plainly that they lack the stereo-linking and mid/sides flexibility that make the Herchild "more appealing for mastering and bus compression gigs."
Best for: matching the unit to your workflow
- Mastering with mid/sides control: The Herchild 670N is the reviewer's top pick here, citing the LAT/VERT modes and the way sides-vs-mid gain staging widened a folk-rock master "almost three-dimensional." The Manley Variable Mu is the next step up in price without documented mid/sides in this source.
- Stereo mastering or mix-bus work, budget-limited: The Grandchild 670/500 at ~$2,000 gets you the Vari-Mu character and stereo linking in a single 500-series slot, without the 670N's rack commitment.
- Tracking two unrelated sources at once: The 670N's IND mode handles true dual-mono work — the reviewer used it to compress dual lead vocals independently, and suggests it would work equally well split between a vocal and a bass line.
- Minimal rack space, no mid/sides needed: The Gainlab Dictator (2U) or Tegeler Vari Tube (3U) take up less room and cost less, but skip the stereo-link and mid/sides features entirely, per the reviewer.
- Maximum vintage-correct build, budget no object: The full Herchild 670 at $10,000 uses 22 NOS valves versus the 670N's 4, for buyers prioritizing component count and the 6U retro look over price.
Documented spec vs. hands-on impression: what to trust for what
Before you shop by this table alone, know which claims are manufacturer fact and which are one reviewer's ears in one room.
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Documented specs (verify on the brand's site):
- Prices: 670N $3,000, Herchild 670 $10,000, Grandchild 670/500 ~$2,000, Manley Variable Mu ~$5,000
- Rack space: 670N 5U, Herchild 670 6U, Grandchild 670/500 single 500-series slot, Gainlab Dictator 2U, Tegeler Vari Tube 3U
- 670N component count: 4 NOS 6BA6 valves, 2 custom input transformers
- 670N operating modes: IND, LINK, LAT, VERT
The reviewer's subjective listening notes (useful context, not guaranteed to match your room or source material):
- The 670N "still feels huge" despite being smaller than the 670
- Sides compressed slightly more than mid produced a "gloriously wide" and "almost three-dimensional" result on a specific folk-rock master
- A "subtle bass thump" from the transformers that the reviewer chose to EQ out before mastering, but might use deliberately on other sources
- The claim that the Dictator and Vari Tube "lack" stereo-linking and mid/sides — stated by the reviewer, not sourced to those brands' own spec sheets in this review
Given the gaps in publicly cited specs for the Manley, Dictator, and Vari Tube, treat this as a starting shortlist, not a final purchase decision. Confirm current pricing, exact rack height, and mode options directly with Manley Labs, Gainlab, and Tegeler before you buy, and read the full Herchild 670N review at MusicTech for the reviewer's complete mix and mastering notes.
